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Sample records for octupole traps structural

  1. Crystallization of ion clouds in octupole traps: Structural transitions, core melting, and scaling laws

    SciTech Connect

    Calvo, F.; Champenois, C.; Yurtsever, E.

    2009-12-15

    The stable structures and melting properties of ion clouds in isotropic octupole traps are investigated using a combination of semianalytical and numerical models, with a particular emphasis at finite-size scaling effects. Small-size clouds are found to be hollow and arranged in shells corresponding approximately to the solutions of the Thomson problem. The shell structure is lost in clusters containing more than a few thousands of ions, the inner parts of the cloud becoming soft and amorphous. While melting is triggered in the core shells, the melting temperature follows the rule expected for three-dimensional dense particles, with a depression scaling linearly with the inverse radius.

  2. Structure and dynamics of ion clusters in linear octupole traps: Phase diagrams, chirality, and melting mechanisms

    SciTech Connect

    Yurtsever, E.; Onal, E. D.; Calvo, F.

    2011-05-15

    The stable structures and melting dynamics of clusters of identical ions bound by linear octupole radiofrequency traps are theoretically investigated by global optimization methods and molecular dynamics simulations. By varying the cluster sizes in the range of 10-1000 ions and the extent of trap anisotropy by more than one order of magnitude, we find a broad variety of stable structures based on multiple rings at small sizes evolving into tubular geometries at large sizes. The binding energy of these clusters is well represented by two contributions arising from isotropic linear and octupolar traps. The structures generally exhibit strong size effects, and chiral arrangements spontaneously emerge in many crystals. Sufficiently large clusters form nested, coaxial tubes with different thermal stabilities. As in isotropic octupolar clusters, the inner tubes melt at temperatures that are lower than the overall melting point.

  3. Cryogenically cooled octupole ion trap for spectroscopy of biomolecular ions.

    PubMed

    Boyarkin, Oleg V; Kopysov, Vladimir

    2014-03-01

    We present here the design of a linear octupole ion trap, suitable for collisional cryogenic cooling and spectroscopy of large ions. The performance of this trap has been assessed using ultraviolet (UV) photofragmentation spectroscopy of protonated dipeptides. At the trap temperature of 6.1 K, the vibrational temperature of the ions reaches 9.1 K, although their estimated translational temperature is ~150 K. This observation suggests that, despite the significant translational heating by radio-frequency electrical field, vibrational cooling of heavy ions in the octupole is at least as efficient as in the 22-pole ion traps previously used in our laboratory. In contrast to the 22-pole traps, excellent radial confinement of ions in the octupole makes it convenient for laser spectroscopy and boosts the dissociation yield of the stored ions to 30%. Overlap of the entire ion cloud by the laser beam in the octupole also allows for efficient UV depletion spectroscopy of ion-He clusters. The measured electronic spectra of the dipeptides and the clusters differ drastically, complicating a use of UV tagging spectroscopy for structural determination of large species.

  4. Cryogenically cooled octupole ion trap for spectroscopy of biomolecular ions

    NASA Astrophysics Data System (ADS)

    Boyarkin, Oleg V.; Kopysov, Vladimir

    2014-03-01

    We present here the design of a linear octupole ion trap, suitable for collisional cryogenic cooling and spectroscopy of large ions. The performance of this trap has been assessed using ultraviolet (UV) photofragmentation spectroscopy of protonated dipeptides. At the trap temperature of 6.1 K, the vibrational temperature of the ions reaches 9.1 K, although their estimated translational temperature is ˜150 K. This observation suggests that, despite the significant translational heating by radio-frequency electrical field, vibrational cooling of heavy ions in the octupole is at least as efficient as in the 22-pole ion traps previously used in our laboratory. In contrast to the 22-pole traps, excellent radial confinement of ions in the octupole makes it convenient for laser spectroscopy and boosts the dissociation yield of the stored ions to 30%. Overlap of the entire ion cloud by the laser beam in the octupole also allows for efficient UV depletion spectroscopy of ion-He clusters. The measured electronic spectra of the dipeptides and the clusters differ drastically, complicating a use of UV tagging spectroscopy for structural determination of large species.

  5. Octupole Excitation of Trapped Ion Motion for Precision Mass Measurements

    NASA Astrophysics Data System (ADS)

    Bollen, G.; Ringle, R.; Schury, P.; Schwarz, S.; Sun, T.

    2005-04-01

    National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI, USA An azimuthal octupole radiofrequency field has been used to excite the ion motion of ^40Ar^+ ions stored in a Penning trap. A resonant response was observed at twice the ions' true cyclotron frequency φc=q/m.B. The experiment has been performed with the 9.4-T Penning trap system of the recently commissioned LEBIT facility at the NSCL at MSU [1]. Similar to the excitation with an azimuthal quadrupole field at φc [2,3], octupole excitation at 2φc gives rise to a periodic beating of the ion motion between magnetron and reduced cyclotron motion. Differences are observed in the dependence of the excited ion motion on initial amplitudes and phases of the radial eigen motions. The observed behavior of the ions is found to be in good agreement with the results of numerical simulations. The technique still requires further testing but the first results indicate that 2φc excitation may provide benefits that are similar to doubling the magnetic field strength B. In particular precision mass measurements of short-lived rare isotopes may benefit from this technique by being able to reach a given precision with shorter ion storage and observation times. [1] S. Schwarz et al, Nucl. Instr. Meth. B204 (2004) 507 [2] G. Bollen et al., J. Appl. Phys. 68 (1990) 4355 [3] M. König et al., Int. J. Mass Spec. Ion. Proc. 142 (1995) 95

  6. Periodic orbits and shell structure in octupole deformed potentials

    SciTech Connect

    Heiss, W.D. ); Nazmitdinov, R.G. ); Radu, S. )

    1995-01-15

    The effect of an octupole term in a quadrupole deformed single-particle potential is studied from the classical and quantum-mechanical viewpoint. Whereas the problem is nonintegrable, the quantum-mechanical spectrum nevertheless shows some shell structure in the superdeformed prolate case for particular, yet fairly large octupole strengths; for spherical or oblate deformation the shell structure disappears. This result is associated with classical periodic orbits that are found by employing the removal of resonances method; this approximation method allows determination of the shape of the orbit and of the approximate octupole coupling strength for which it occurs. The validity of the method is confirmed by solving numerically the classical equations of motion. The quantum-mechanical shell structure is analyzed using the particle-number dependence of the fluctuating part of the total energy. In accordance with the classical result, this dependence turns out to be very similar for a superdeformed prolate potential plus octupole term and a hyperdeformed prolate potential without octupole term. In this way the shell structure is explained at least for some few hundred levels. The Fourier transform of the level density further corroborates these findings.

  7. Construction and Operational Experience with a Superconducting Octupole Used to Trap Antihydrogen

    SciTech Connect

    Wanderer P.; Escallier, J.; Marone, A.; Parker, B.

    2011-09-06

    A superconducting octupole magnet has seen extensive service as part of the ALPHA experiment at CERN. ALPHA has trapped antihydrogen, a crucial step towards performing precision measurements of anti-atoms. The octupole was made at the Direct Wind facility by the Superconducting Magnet Division at Brookhaven National Laboratory. The magnet was wound with a six-around-one NbTi cable about 1 mm in diameter. It is about 300 mm long, with a radius of 25 mm and a peak field at the conductor of 4.04 T. Specific features of the magnet, including a minimal amount of material in the coil and coil ends with low multipole content, were advantageous to its use in ALPHA. The magnet was operated for six months a year for five years. During this time it underwent about 900 thermal cycles (between 4K and 100K). A novel operational feature is that during the course of data-taking the magnet was repeatedly shut off from its 950 A operating current. The magnet quenches during the shutoff, with a decay constant of 9 ms. Over the course of the five years, the magnet was deliberately quenched many thousands of times. It still performs well.

  8. Structural traps 5

    SciTech Connect

    Foster, N.H.; Beaumont, E.A.

    1991-01-01

    This book contains studies of oil and gas fields that are mainly structural in nature. Stratigraphy controls the extend of the reservoir in the traps of several fields, but overall, the main trapping features within the group of fields in this volume are structural. Fields covered in this volume include: Endicott Field, Point Arguello Field, West Puerto Chiquito Field, Dukhan Field, Sendji Field, Ruston Field, Raudhatain Field, Hassi Messaoud Field, Snapper Field, Tirrawarra Field, and Sacha Field.

  9. Studies of Octupole Structures in RADON-220,222 and RADIUM-224.

    NASA Astrophysics Data System (ADS)

    Poynter, Raymond John

    Available from UMI in association with The British Library. alpha-gamma angular correlation measurements have been made using the alpha-radioactive sources ^{226}Ra and ^{228}Th in the POLYTESSA array at the N.S.F., Daresbury Laboratory. These measurements enabled spin-parity (J^{pi}) assignments to be made to nuclei in the two decay chains. The J^{pi} assignments have been made as follows; 1^ {-} and 3^{-} to the 601 and 635keV levels (respectively) in ^{222}Rn, 1^ {-} to the 645 keV level in ^ {220}Rn, 2^{+} to the 510 and 550keV levels (the first excited states) in ^{218,216}Po respectively, 4^{+} to the 250keV level in ^{224}Ra and 4^{+} to the 448 and 534 levels in ^{222,220}Rn respectively. alpha-e^ {-} coincidence measurements with the ^{228}Th source in the superconducting electron solenoid spectrometer also at the N.S.F. have been performed and the internal conversion coefficient for the 205keV transition in ^ {224}Ra has been measured. The 205keV transition was demonstrated to be an E1 transition, thus the 292keV level is assigned as having J^ {pi}=3^{-} (or 1^{-}). These J ^{pi} assignments have enabled interpretation of alpha hindrance factors to the low-lying negative parity levels in these radium and radon nuclei. The systematics of alpha hindrance factors in these nuclei are compared with others from the region. A preliminary experiment on the higher spin structure of ^{224}Ra has been performed utilising the ^{226}Ra (^{58}Ni,^ {60}Ni)^{224} Ra^{*} reaction, also on the POLYTESSA array. The use of a transfer reaction necessitated the event-by-event correction of the Doppler shift of the gamma-rays. The experimental apparatus used to enable this correction is described. gamma-gamma coincidence spectroscopy was performed and a tentative decay scheme constructed up to a spin of 10hbar . B(E1)/B(E2) branching ratios were measured to be 5.5 +/- 1 times 10^{-7}fm ^{-2} and a provisional intrinsic dipole moment of Q_1 = 0.24 +/- 0.05efm for ^ {224}Ra was

  10. Octupole correlations in the heavy elements

    SciTech Connect

    Chasman, R.R.

    1986-01-01

    The effects of octupole correlations on the nuclear structure of the heavy elements are discussed. The cluster model description of the heavy elements is analyzed. The relevance of 2/sup 6/-pole deformation and fast El transitions to an octupole model is considered. 30 refs., 21 figs., 1 tab.

  11. Octupole shapes in heavy nuclei

    SciTech Connect

    Ahmad, I.

    1994-08-01

    Theoretical calculations and measurements show the presence of strong octupole correlations in thecyround states and low-lying states of odd-mass and odd-odd nuclei in the RaPa region. Evidence for octupole correlations is provided by the observation of parity doublets and reductions in M1 matrix elements, decoupling parameters, and Coriolis matrix elements Involving high-j states. Enhancement of E1 transition rates has also been observed for some of the octupole deformed nuclei. The most convincing argument for octupole deformation is provided by the similarities of the reduced alpha decay rates to the two members of parity doublets.

  12. Measuring the full transverse beam matrix using a single octupole

    NASA Astrophysics Data System (ADS)

    Ögren, J.; Ruber, R.; Ziemann, V.; Farabolini, W.

    2015-07-01

    We propose a method to fully determine the transverse beam matrix using a simple setup consisting of two steering magnets, an octupole field and a screen. This works in principle for any multipole field, i.e., sextupole, octupole magnet or a radio frequency structure with a multipole field. We have experimentally verified the method at the Compact Linear Collider Test Facility 3 at CERN using a Compact Linear Collider accelerating structure, which has an octupole component of the radio frequency fields. By observing the position shifts of the beam centroid together with changes in transverse beam size on a screen, we determined the full transverse beam matrix, with all correlations.

  13. Octupole correlation effects in nuclei

    SciTech Connect

    Chasman, R.R.

    1992-01-01

    Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.

  14. Octupole correlation effects in nuclei

    SciTech Connect

    Chasman, R.R.

    1992-08-01

    Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.

  15. High-precision Penning-trap mass measurements of heavy xenon isotopes for nuclear structure studies

    SciTech Connect

    Neidherr, D.; Cakirli, R. B.; Audi, G.; Lunney, D.; Minaya-Ramirez, E.; Naimi, S.; Beck, D.; Herfurth, F.; Blaum, K.; Boehm, Ch.; George, S.; Breitenfeldt, M.; Rosenbusch, M.; Schweikhard, L.; Casten, R. F.; Herlert, A.; Kowalska, M.; Kellerbauer, A.; Schwarz, S.

    2009-10-15

    With the double Penning-trap mass spectrometer ISOLTRAP at ISOLDE/CERN the masses of the neutron-rich isotopes {sup 136-146}Xe were measured with a relative uncertainty of the order of 10{sup -8} to 10{sup -7}. In particular, the masses of {sup 144-146}Xe were measured for the first time. These new mass values allow one to extend calculations of the mass surface in this region. Proton-Neutron interaction strength, obtained from double differences of binding energies, relate to subtle structural effects, such as the onset of octupole correlations, the growth of collectivity, and its relation to the underlying shell model levels. In addition, they provide a test of density functional calculations.

  16. Proposed s =±1 octupole bands in 140Xe

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Zhu, S. J.; Hamilton, J. H.; Wang, E. H.; Ramayya, A. V.; Xiao, Z. G.; Li, H. J.; Luo, Y. X.; Rasmussen, J. O.; Ter-Akopian, G. M.; Oganessian, Yu. Ts.

    2016-06-01

    Level structures of neutron-rich 140Xe nucleus have been reinvestigated by using a triple γ coincidence study from the spontaneous fission of 252Cf. Several new levels and transitions are identified. The previously observed s =+1 octupole band structure is confirmed and expanded. Another set of the Δ I =2 positive and negative parity bands connected by strong E 1 transitions is proposed as the s =-1 octupole band structure. Thus, the s =±1 doublet octupole bands are completed in 140Xe. The experimental B (E 1 )/B (E 2 ) branching ratios indicate that the octupole correlations in 140Xe are weak. The other characteristics of the s =±1 octupole bands have been discussed.

  17. Enhanced optical trapping via structured scattering

    NASA Astrophysics Data System (ADS)

    Taylor, Michael A.; Waleed, Muhammad; Stilgoe, Alexander B.; Rubinsztein-Dunlop, Halina; Bowen, Warwick P.

    2015-10-01

    Interferometry can completely redirect light, providing the potential for strong and controllable optical forces. However, small particles do not naturally act like interferometric beamsplitters and the optical scattering from them is not generally thought to allow efficient interference. Instead, optical trapping is typically achieved via deflection of the incident field. Here, we show that a suitably structured incident field can achieve beamsplitter-like interactions with scattering particles. The resulting trap offers order-of-magnitude higher stiffness than the usual Gaussian trap in one axis, even when constrained to phase-only structuring. We demonstrate trapping of 3.5-10.0 μm silica spheres, achieving a stiffness up to 27.5 ± 4.1 times higher than was possible using Gaussian traps as well as a two-orders-of-magnitude higher measured signal-to-noise ratio. These results are highly relevant to many applications, including cellular manipulation, fluid dynamics, micro-robotics and tests of fundamental physics.

  18. Octupole correlations in the 144Ba nucleus described with symmetry-conserving configuration-mixing calculations

    NASA Astrophysics Data System (ADS)

    Bernard, Rémi N.; Robledo, Luis M.; Rodríguez, Tomás R.

    2016-06-01

    We study the interplay of quadrupole and octupole degrees of freedom in the structure of the isotope 144Ba. A symmetry-conserving configuration-mixing method (SCCM) based on a Gogny energy density functional (EDF) has been used. The method includes particle number, parity, and angular momentum restoration as well as axial quadrupole and octupole shape mixing within the generator coordinate method. Predictions both for excitation energies and electromagnetic transition probabilities are in good agreement with the most recent experimental data.

  19. Octupole correlations in low-lying states of 150Nd and 150Sm and their impact on neutrinoless double-β decay

    NASA Astrophysics Data System (ADS)

    Yao, J. M.; Engel, J.

    2016-07-01

    We present a generator-coordinate calculation, based on a relativistic energy-density functional, of the low-lying spectra in the isotopes 150Nd and 150Sm and of the nuclear matrix element that governs the neutrinoless double-β decay of the first isotope to the second. We carefully examine the impact of octupole correlations on both nuclear structure and the double-β decay matrix element. Octupole correlations turn out to reduce quadrupole collectivity in both nuclei. Shape fluctuations, however, dilute the effects of octupole deformation on the double-β decay matrix element, so that the overall octupole-induced quenching is only about 7 % .

  20. Nonaxial-octupole effect in superheavy nuclei

    SciTech Connect

    Chen, Y.-S.; Sun, Yang; Gao Zaochun

    2008-06-15

    The triaxial-octupole Y{sub 32} correlation in atomic nuclei has long been expected to exist but experimental evidence has not been clear. We find, in order to explain the very low-lying 2{sup -} bands in the transfermium mass region, that this exotic effect may manifest itself in superheavy elements. Favorable conditions for producing triaxial-octupole correlations are shown to be present in the deformed single-particle spectrum, which is further supported by quantitative Reflection Asymmetric Shell Model calculations. It is predicted that the strong nonaxial-octupole effect may persist up to the element 108. Our result thus represents the first concrete example of spontaneous breaking of both axial and reflection symmetries in the heaviest nuclear systems.

  1. Octupole Deformation Bands of πh11/2 in Neutron-Rich 145,147La Nuclei

    NASA Astrophysics Data System (ADS)

    Zhu, Sheng-jiang; S, Zhu J.; Wang, Mu-ge; J, Hamilton H.; A, Ramayya V.; B, Babu R. S.; W, Ma C.; Long, Gui-lu; Zhu, Ling-yan; Li, Ming; A, Sakhaee; Gan, Cui-yun; Yang, Li-ming; J, Komicki; J, Cole D.; R, Aryaeinejad; M, Drigert W.; J, Rasmussen O.; M, Stoyer A.; S, Chu Y.; K, Gregorich E.; M, Mohar F.; S, Prussin G.; I, Lee Y.; Yu, Oganessian Ts; G, Ter-Akopian M.; A, Daniel V.

    1999-03-01

    Octupole deformation bands built on πh11/2 orbital in neutron-rich odd-Z 145,147La nuclei have been investigated by measuring the prompt γ-rays emitted from the 252Cf source. The alternating parity band structures and strong E1 transitions observed between negative- and positive-parity bands in both nuclei indicate the octupole deformation enhanced by the h11/2 single proton coupling. According to observed energy displacements the octupole deformation becomes stable at the intermediate spin states.

  2. A novel antiproton radial diagnostic based on octupole induced ballistic loss

    SciTech Connect

    Andresen, G. B.; Bowe, P. D.; Hangst, J. S.; Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Jenkins, M. J.; Joergensen, L. V.; Madsen, N.; Werf, D. P. van der; Bray, C. C.; Chapman, S.; Fajans, J.; Povilus, A.; Wurtele, J. S.; Cesar, C. L.; Lambo, R.; Silveira, D. M.; Fujiwara, M. C.

    2008-03-15

    We report results from a novel diagnostic that probes the outer radial profile of trapped antiproton clouds. The diagnostic allows us to determine the profile by monitoring the time history of antiproton losses that occur as an octupole field in the antiproton confinement region is increased. We show several examples of how this diagnostic helps us to understand the radial dynamics of antiprotons in normal and nested Penning-Malmberg traps. Better understanding of these dynamics may aid current attempts to trap antihydrogen atoms.

  3. Collective states of odd nuclei in a model with quadrupole-octupole degrees of freedom

    SciTech Connect

    Minkov, N. Drenska, S. B.; Yotov, P.; Bonatsos, D. Scheid, W.

    2007-08-15

    We apply the collective axial quadrupole-octupole Hamiltonian to describe the rotation-vibration motion of odd nuclei with Coriolis coupling between the even-even core and the unpaired nucleon.We consider that the core oscillates coherently with respect to the quadrupole and octupole axialdeformation variables. The coupling between the core and the unpaired nucleon provides a split paritydoublet structure of the spectrum. The formalism successfully reproduces the parity-doublet splitting in a wide range of odd-A nuclei. It provides model estimations for the third angular-momentum projection K on the intrinsic symmetry axis and the related intrinsic nuclear structure.

  4. Crystal structure of unliganded TRAP: implications for dynamic allostery.

    PubMed

    Malay, Ali D; Watanabe, Masahiro; Heddle, Jonathan G; Tame, Jeremy R H

    2011-03-15

    Allostery is vital to the function of many proteins. In some cases, rather than a direct steric effect, mutual modulation of ligand binding at spatially separated sites may be achieved through a change in protein dynamics. Thus changes in vibrational modes of the protein, rather than conformational changes, allow different ligand sites to communicate. Evidence for such an effect has been found in TRAP (trp RNA-binding attenuation protein), a regulatory protein found in species of Bacillus. TRAP is part of a feedback system to modulate expression of the trp operon, which carries genes involved in tryptophan synthesis. Negative feedback is thought to depend on binding of tryptophan-bound, but not unbound, TRAP to a specific mRNA leader sequence. We find that, contrary to expectations, at low temperatures TRAP is able to bind RNA in the absence of tryptophan, and that this effect is particularly strong in the case of Bacillus stearothermophilus TRAP. We have solved the crystal structure of this protein with no tryptophan bound, and find that much of the structure shows little deviation from the tryptophan-bound form. These data support the idea that tryptophan may exert its effect on RNA binding by TRAP through dynamic and not structural changes, and that tryptophan binding may be mimicked by low temperature. PMID:21175426

  5. Structured interference force for enhanced optical trapping (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Taylor, Michael A.; Waleed, Muhammad; Stilgoe, Alexander B.; Rubinsztein-Dunlop, Halina; Bowen, Warwick P.

    2015-08-01

    Interferometry can completely redirect light, providing the potential for exceptionally strong and controllable optical forces. When a beamsplitter combines two fields, the output power is directed via the relative phase between the incident fields. Since the phase changes with beamsplitter displacement, the interference force can be used to stably trap; with displacements as small as (λ/4n) able to completely redirect the light. The resulting change in optical momentum causes an opposing optical force. However, optical forces are most useful for trapping and manipulating small scattering particles. Optical scattering is not generally thought to allow efficient interference; essentially, it appears that small particles cannot act as beamsplitters. As such, optical traps have relied upon much weaker deflection-based forces. Here we show that efficient interference can be achieved by appropriately structuring the incident light. This relies on Mie scattering fringes to combine light which is incident from different incident angles. This results in a force, which we call the structured interference force, which offers order-of-magnitude higher trap stiffness over the usual Gaussian trap. We demonstrate structured interference force trapping (SIFT) of 10μm diameter silica spheres with a stiffness 20.1 times higher than is possible using Gaussian traps, while also increasing the measurement signal-to-noise ratio by two orders of magnitude. This is demonstrated using only phase control of the incident light, making the technique directly compatible with most existing holographic optical traps. These results are highly relevant to many applications, including cellular manipulation, fluid dynamics, micro-robotics, and tests of fundamental physics.

  6. Evolution of octupole correlations in 123Ba

    NASA Astrophysics Data System (ADS)

    Chen, X. C.; Zhao, J.; Xu, C.; Hua, H.; Shneidman, T. M.; Zhou, S. G.; Wu, X. G.; Li, X. Q.; Zhang, S. Q.; Li, Z. H.; Liang, W. Y.; Meng, J.; Xu, F. R.; Qi, B.; Ye, Y. L.; Jiang, D. X.; Cheng, Y. Y.; He, C.; Sun, J. J.; Han, R.; Niu, C. Y.; Li, C. G.; Li, P. J.; Wang, C. G.; Wu, H. Y.; Li, Z. H.; Zhou, H.; Hu, S. P.; Zhang, H. Q.; Li, G. S.; He, C. Y.; Zheng, Y.; Li, C. B.; Li, H. W.; Wu, Y. H.; Luo, P. W.; Zhong, J.

    2016-08-01

    High-spin states of 123Ba have been studied via the 108Cd(19F,3 n p )123Ba fusion-evaporation reaction at a beam energy of 90 MeV. Several E 1 transitions linking the positive-parity ν (d5 /2+g7 /2) band and negative-parity ν h11 /2 band are observed in 123Ba for the first time. Evidence for the existence of octupole correlations in 123Ba is presented based on the systematic comparisons of the B (E 1 )/B (E 2 ) branching ratios and the energy displacements in odd-A Ba isotopes. The characteristics of octupole correlation in the odd-A Ba,125123 are explained by the state-of-the-art multidimensionally-constrained relativistic mean-field model and cluster model based on the dinuclear system concept.

  7. First Attempts at Antihydrogen Trapping in ALPHA

    SciTech Connect

    Andresen, G. B.; Bowe, P. D.; Hangst, J. S.; Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Jenkins, M. J.; Joergensen, L. V.; Madsen, N.; Werf, D. P. van der; Bray, C. C.; Chapman, S.; Fajans, J.; Povilus, A.; Wurtele, J. S.; Cesar, C. L.; Lambo, R.; Silveira, D. M.; Fujiwara, M. C.

    2008-08-08

    The ALPHA apparatus is designed to produce and trap antihydrogen atoms. The device comprises a multifunction Penning trap and a superconducting, neutral atom trap having a minimum-B configuration. The atom trap features an octupole magnet for transverse confinement and solenoidal mirror coils for longitudinal confinement. The magnetic trap employs a fast shutdown system to maximize the probability of detecting the annihilation of released antihydrogen. In this article we describe the first attempts to observe antihydrogen trapping.

  8. First Attempts at Antihydrogen Trapping in ALPHA

    NASA Astrophysics Data System (ADS)

    Andresen, G. B.; Bertsche, W.; Bowe, P. D.; Bray, C. C.; Butler, E.; Cesar, C. L.; Chapman, S.; Charlton, M.; Fajans, J.; Fujiwara, M. C.; Funakoshi, R.; Gill, D. R.; Hangst, J. S.; Hardy, W. N.; Hayano, R. S.; Hayden, M. E.; Humphries, A. J.; Hydomako, R.; Jenkins, M. J.; Jørgensen, L. V.; Kurchaninov, L.; Lambo, R.; Madsen, N.; Nolan, P.; Olchanski, K.; Olin, A.; Page, R. D.; Povilus, A.; Pusa, P.; Robicheaux, F.; Sarid, E.; El Nasr, S. Seif; Silveira, D. M.; Storey, J. W.; Thompson, R. I.; van der Werf, D. P.; Wurtele, J. S.; Yamazaki, Y.

    2008-08-01

    The ALPHA apparatus is designed to produce and trap antihydrogen atoms. The device comprises a multifunction Penning trap and a superconducting, neutral atom trap having a minimum-B configuration. The atom trap features an octupole magnet for transverse confinement and solenoidal mirror coils for longitudinal confinement. The magnetic trap employs a fast shutdown system to maximize the probability of detecting the annihilation of released antihydrogen. In this article we describe the first attempts to observe antihydrogen trapping.

  9. Hitting and trapping times on branched structures.

    PubMed

    Agliari, Elena; Sartori, Fabio; Cattivelli, Luca; Cassi, Davide

    2015-05-01

    In this work we consider a simple random walk embedded in a generic branched structure and we find a close-form formula to calculate the hitting time H(i,f) between two arbitrary nodes i and j. We then use this formula to obtain the set of hitting times {H(i,f)} for combs and their expectation values, namely, the mean first-passage time, where the average is performed over the initial node while the final node f is given, and the global mean first-passage time, where the average is performed over both the initial and the final node. Finally, we discuss applications in the context of reaction-diffusion problems. PMID:26066144

  10. Generation of gravitational waves: The post Newtonian spin octupole moment

    NASA Astrophysics Data System (ADS)

    Damour, T.; Iyer, B. R.

    1993-12-01

    Using the gravitational wave formalism developed by Blanchet, Damour, and Iyer, this note computes the post-Newtonian-accurate spin octupole moment. The result is checked by explicitly verifying the transformation of the radiative spin octupole moment under shifts of the spatial origin.

  11. Computing the Partition Function for Kinetically Trapped RNA Secondary Structures

    PubMed Central

    Lorenz, William A.; Clote, Peter

    2011-01-01

    An RNA secondary structure is locally optimal if there is no lower energy structure that can be obtained by the addition or removal of a single base pair, where energy is defined according to the widely accepted Turner nearest neighbor model. Locally optimal structures form kinetic traps, since any evolution away from a locally optimal structure must involve energetically unfavorable folding steps. Here, we present a novel, efficient algorithm to compute the partition function over all locally optimal secondary structures of a given RNA sequence. Our software, RNAlocopt runs in time and space. Additionally, RNAlocopt samples a user-specified number of structures from the Boltzmann subensemble of all locally optimal structures. We apply RNAlocopt to show that (1) the number of locally optimal structures is far fewer than the total number of structures – indeed, the number of locally optimal structures approximately equal to the square root of the number of all structures, (2) the structural diversity of this subensemble may be either similar to or quite different from the structural diversity of the entire Boltzmann ensemble, a situation that depends on the type of input RNA, (3) the (modified) maximum expected accuracy structure, computed by taking into account base pairing frequencies of locally optimal structures, is a more accurate prediction of the native structure than other current thermodynamics-based methods. The software RNAlocopt constitutes a technical breakthrough in our study of the folding landscape for RNA secondary structures. For the first time, locally optimal structures (kinetic traps in the Turner energy model) can be rapidly generated for long RNA sequences, previously impossible with methods that involved exhaustive enumeration. Use of locally optimal structure leads to state-of-the-art secondary structure prediction, as benchmarked against methods involving the computation of minimum free energy and of maximum expected accuracy. Web server

  12. Computing the partition function for kinetically trapped RNA secondary structures.

    PubMed

    Lorenz, William A; Clote, Peter

    2011-01-01

    An RNA secondary structure is locally optimal if there is no lower energy structure that can be obtained by the addition or removal of a single base pair, where energy is defined according to the widely accepted Turner nearest neighbor model. Locally optimal structures form kinetic traps, since any evolution away from a locally optimal structure must involve energetically unfavorable folding steps. Here, we present a novel, efficient algorithm to compute the partition function over all locally optimal secondary structures of a given RNA sequence. Our software, RNAlocopt runs in O(n3) time and O(n2) space. Additionally, RNAlocopt samples a user-specified number of structures from the Boltzmann subensemble of all locally optimal structures. We apply RNAlocopt to show that (1) the number of locally optimal structures is far fewer than the total number of structures--indeed, the number of locally optimal structures approximately equal to the square root of the number of all structures, (2) the structural diversity of this subensemble may be either similar to or quite different from the structural diversity of the entire Boltzmann ensemble, a situation that depends on the type of input RNA, (3) the (modified) maximum expected accuracy structure, computed by taking into account base pairing frequencies of locally optimal structures, is a more accurate prediction of the native structure than other current thermodynamics-based methods. The software RNAlocopt constitutes a technical breakthrough in our study of the folding landscape for RNA secondary structures. For the first time, locally optimal structures (kinetic traps in the Turner energy model) can be rapidly generated for long RNA sequences, previously impossible with methods that involved exhaustive enumeration. Use of locally optimal structure leads to state-of-the-art secondary structure prediction, as benchmarked against methods involving the computation of minimum free energy and of maximum expected accuracy

  13. Search for two-phonon octupole excitations in 146Gd

    NASA Astrophysics Data System (ADS)

    Orce, J. N.; Kumar Raju, M.; Khumalo, N. A.; Dinoko, T. S.; Jones, P.; Bark, R. A.; Lawrie, E. A.; Majola, S. N. T.; Robledo, L. M.; Rubio, B.; Wiedeking, M.; Easton, J.; Khaleel, E. A.; Kheswa, B. V.; Kheswa, N.; Herbert, M. S.; Lawrie, J. J.; Masiteng, P. L.; Nchodu, M. R.; Ndayishimye, J.; Negi, D.; Noncolela, S. P.; Ntshangase, S. S.; Papka, P.; Roux, D. G.; Shirinda, O.; Sithole, P. S.; Yates, S. W.

    2016-06-01

    The low-spin structure of the nearly spherical nucleus 146Gd was studied using the 144Sm(4He, 2n) fusion-evaporation reaction. High-statistics γ - γ coincidence measurements were performed at iThemba LABS with 7× 109 γ- γ coincidence events recorded. Gated γ-ray energy spectra show evidence for the 6+2 → 3-1 → 0+1 cascade of E3 transitions in agreement with recent findings by Caballero and co-workers, but with a smaller branching ratio of I_{γ} = 4.7(10) for the 6+2 → 3-1 1905.1 keV γ ray. Although these findings may support octupole vibrations in spherical nuclei, sophisticated beyond mean-field calculations including angular-momentum projection are required to interpret in an appropriate way the available data due to the failure of the rotational model assumptions in this nucleus.

  14. Precision Penning Trap Mass Measurements for Nuclear Structure at Triumf

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, A. A.; Dilling, J.; Andreoiu, C.; Brunner, T.; Chaudhuri, A.; Chowdhury, U.; Delheij, P.; Ettenauer, S.; Frekers, D.; Gallant, A. T.; Grossheim, A.; Gwinner, G.; Lennarz, A.; Mané, E.; Pearson, M. R.; Schultz, B. E.; Simon, M. C.; Simon, V. V.

    2013-03-01

    Precision determinations of ground state or even isomeric state masses reveal fingerprints of nuclear structure. In particular at the limits at existence for very neutron-rich or deficient isotopes, this allows one to find detailed information about nuclear structure from separation energies or binding energies. This is important to test theoretical predictions or to refine model approaches, for example for new "magic numbers," as predicted around N = 34, where strong indications exist that the inclusion of NNN forces in theoretical calculations for Ca isotopes leads to significantly better predictions for ground state binding energies. Similarly, halo nuclei present an excellent application for ab-initio theory, where ground state properties, like masses and radii, present prime parameters for testing our understanding of nuclear structure. Precision mass determinations at TRIUMF are carried out with the TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) system. It is an ion trap setup coupled to the on-line facility ISAC. TITAN has measured masses of isotopes as short-lived as 9 ms (almost an order of magnitude shorter-lived than any other Penning trap system) and the only one with charge breeding capabilities, a feature that allows us to boost the precision by almost 2 orders of magnitude. We recently were able to make use of this feature by measuring short-lived Rb-isotopes, up to 74Rb, and reaching the 12+ charge state, which together with other improvements lead to an increase in precision by a factor 36.

  15. Octupole and hexadecapole bands in 152Sm

    SciTech Connect

    Garrett, P E; Kulp, W D; Wood, J L; Bandyopadhyay, D; Christen, S; Choudry, S; Dewald, A; Fitzler, A; Fransen, C; Jessen, K; Jolie, J; Kloezer, A; Kudejova, P; Kumar, A; Lesher, S R; Linnemann, A; Lisetskiy, A; Martin, D; Masur, M; McEllistrem, M T; Moller, O; Mynk, M; Orce, J N; Pejovic, P; Pissulla, T; Regis, J; Schiller, A; Tonev, D; Yates, S W

    2005-05-13

    The nucleus {sup 152}Sm is characterized by a variety of low-energy collective modes, conventionally described as rotations, {beta} vibrations, and {gamma} vibrations. Recently, it has been suggested that {sup 152}Sm is at a critical point between spherical and deformed collective phases. Consequently, {sup 152}Sm is being studied by a variety of techniques, including radioactive decay, multi-step Coulomb excitation, in-beam ({alpha},2n{gamma}) {gamma}-ray spectroscopy, and (n,n'{gamma}) spectroscopy. The present work focuses on the latter two reactions; these have been used to investigate the low-lying bands associated with the octupole degree of freedom, including one built on the first excited 0{sup +} band. In addition, the K{sup {pi}} = 4{sup +} hexadecapole vibrational band has been identified.

  16. Chaos in axially symmetric potentials with octupole deformation

    SciTech Connect

    Heiss, W.D.; Nazmitdinov, R.G.; Radu, S. Departamento de Fisica Teorica C-XI, Universidad Autonoma de Madrid, E-28049, Madrid )

    1994-04-11

    Classical and quantum mechanical results are reported for the single particle motion in a harmonic oscillator potential which is characterized by a quadrupole deformation and an additional octupole deformation. The chaotic character of the motion is strongly dependent on the quadrupole deformation in that for a prolate deformation virtually no chaos is discernible while for the oblate case the motion shows strong chaos when the octupole term is turned on.

  17. Octupole response and stability of spherical shape in heavy nuclei

    NASA Astrophysics Data System (ADS)

    Abrosimov, V. I.; Davidovskaya, O. I.; Dellafiore, A.; Matera, F.

    2003-11-01

    The isoscalar octupole response of a heavy spherical nucleus is analyzed in a semiclassical model based on the linearized Vlasov equation. The octupole strength function is evaluated with different degrees of approximation. The zero-order fixed-surface response displays a remarkable concentration of strength in the 1ℏ ω and 3ℏ ω regions, in excellent agreement with the quantum single-particle response. The collective fixed-surface response reproduces both the high- and low-energy octupole resonances, but not the low-lying 3 - collective states, while the moving-surface response function gives a good qualitative description of all the main features of the octupole response in heavy nuclei. The role of triangular nucleon orbits, that have been related to a possible instability of the spherical shape with respect to octupole-type deformations, is discussed within this model. It is found that, rather than creating instability, the triangular trajectories are the only classical orbits contributing to the damping of low-energy octupole excitations.

  18. Coherent quadrupole-octupole modes and split parity-doublet spectra in odd-A nuclei

    SciTech Connect

    Minkov, N.; Drenska, S.; Yotov, P.; Lalkovski, S.; Bonatsos, D.; Scheid, W.

    2007-09-15

    A collective model describing coherent quadrupole-octupole oscillations and rotations with a Coriolis coupling between the even-even core and the unpaired nucleon is applied to odd nuclei. The particle-core coupling provides a parity-doublet structure of the spectrum, whereas the quadrupole-octupole motion leads to a splitting of the doublet energy levels. The formalism successfully reproduces the split parity-doublet spectra and the attendant B(E1) and B(E2) transition probabilities in a wide range of odd-A nuclei. It provides estimations for the influence of the Coriolis interaction on the collective motion and subsequently for the value of angular momentum projection K on which the spectrum is built. The analysis of the energy splitting and B(E1) transition probabilities between opposite parity counterparts suggests degenerate doublet structures at high angular momenta. The study provides information about the evolution of quadrupole-octupole collectivity in odd-mass nuclei.

  19. Spectroscopy of quadrupole and octupole states in rare-earth nuclei from a Gogny force

    NASA Astrophysics Data System (ADS)

    Nomura, K.; Rodríguez-Guzmán, R.; Robledo, L. M.

    2015-07-01

    Collective quadrupole and octupole states are described in a series of Sm and Gd isotopes within the framework of the interacting boson model (IBM), whose Hamiltonian parameters are deduced from mean-field calculations with the Gogny energy density functional. The link between both frameworks is the (β2β3 ) potential energy surface computed within the Hartree-Fock-Bogoliubov framework in the case of the Gogny force. The diagonalization of the IBM Hamiltonian provides excitation energies and transition strengths of an assorted set of states including both positive- and negative-parity states. The resultant spectroscopic properties are compared with the available experimental data and also with the results of the configuration mixing calculations with the Gogny force within the generator coordinate method (GCM). The structure of excited 0+ states and its connection with double-octupole phonons is also addressed. The model is shown to describe the empirical trend of the low-energy quadrupole and octupole collective structure fairly well and turns out to be consistent with GCM results obtained with the Gogny force.

  20. Octupole shaps in nuclei, and some rotational consequences thereof

    SciTech Connect

    Nazarewicz, W.; Olanders, P.; Ragnarsson, I.; Dudek, J.; Leander, G.A.

    1984-01-01

    During the last years a large number of experimental papers presenting spectroscopic evidence for collective dipole and octupole deformations have appeared. Many theoretical attempts have been made to explain the observed spectroscopic properties in terms of stable octupole deformations. The coupling by the octupole potential, being proportional to Y/sub 30/, is strongest for those subshells for which ..delta..1 = 3. Therefore the tendency towards octupole deformation occurs just beyond closed shells where the high-j intruder subshells (N,1,j) lie very close to the normal parity subshells (N-1,1-3,j-3), i.e. for the particle numbers 34 (g/sub 9/2/-p/sub 3/2/), 56 (h/sub 11/2/-d/sub 5/2/). 9C (i/sub 13/2/-f/sub 7/2/) and 134 (j/sub 15/2/-g/sub 9/2/). Empirically, it is specifically for the particle numbers listed above that negative parity states are observed at relatively low energies in doubly even nuclei. From the different combinations of octupole-driving particle numbers four regions of likely candidates for octupole deformed equilibrium shapes emerge, namely the neutron-deficient nuclei with Z approx. = 90, N approx. = 134 (light actinides) and Z approx. = 34, N approx. = 34 (A approx. = 70) and the neutron-rich nuclei with Z approx. = 56, N approx. = 90 (heavy Ba) and Z approx. = 34, N/sup 56/ (A approx. = 90). In our calculations we searched for octupole unstable nuclei in these four mass regions. The Strutinsky method with the deformed Woods-Saxon potential was employed. The macroscopic part consists of a finite-range liquid drop energy, where both the surface and Coulomb terms contain a diffuseness correction.

  1. Extraterrestrial Helium Trapped in Fullerenes in the Sudbury Impact Structure

    NASA Technical Reports Server (NTRS)

    Becker, Luann; Poreda, Robert J.; Bada, Jeffrey L.

    1996-01-01

    Fullerenes (C60 and C70) in the Sudbury impact structure contain trapped helium with a He-3/He-4 ratio of 5.5 x 10(exp -4) to 5.9 x 10(exp -4). The He-3/He-4 ratio exceeds the accepted solar wind value by 20 to 30 percent and is higher by an order of magnitude than the maximum reported mantle value. Terrestrial nuclear reactions or cosmic-ray bombardment are not sufficient to generate such a high ratio. The He-3/He-4 ratios in the Sudbury fullerenes are similar to those found in meteorites and in some interplanetary dust particles. The implication is that the helium within the C60 molecules at Sudbury is of extraterrestrial origin.

  2. Measurement of tune spread in the Tevatron versus octupole strength

    SciTech Connect

    Marriner, John; Martens, Mike; /Fermilab

    1996-08-01

    An experiment was performed in the Tevatron to measure the tune spread versus octupole strength. The experiment is sensitive to the relationship between octupole strength and current in the T:OZF circuit and to the octupole (and other non-linear focusing fields) in the Tevatron. The major motivation for the experiment was to determine the value of octupole excitation that minimizes the tune spread: this value is an estimate of the value required to obtain ''zero'' total octupole excitation in the extraction process. The experiment was performed using the strip-line kickers at A17 and the resonant Schottky pickups. The horizontal proton kicker was excited with a sine-wave from a vector signal analyzer (HP-89440A) and the horizontal proton signal was received. The gating circuitry normally used to select proton or antiproton bunches was by-passed. The response function was measured and recorded on a floppy disk. Measurements were initially made with a 200 Hz span (0.250 Hz frequency bins) and later with a 100 Hz span (0.125 Hz frequency bins).

  3. Global systematics of octupole excitations in even-even nuclei

    NASA Astrophysics Data System (ADS)

    Robledo, L. M.; Bertsch, G. F.

    2011-11-01

    We present a computational methodology for a theory of the lowest axially symmetric octupole excitations applicable to all even-even nuclei beyond the lightest. The theory is the well-known generator-coordinate extension (GCM) of the Hartree-Fock-Bogoliubov (HFB) self-consistent mean field theory. We use the discrete-basis Hill-Wheeler (HW) method to compute the wave functions with an interaction from the Gogny family of Hamiltonians. Comparing to the compiled experimental data on octupole excitations, we find that the performance of the theory depends on the deformation characteristics of the nucleus. For nondeformed nuclei, the theory reproduces the energies to about ±20% apart from an overall scale factor of ≈1.6. The performance is somewhat poorer for (quadrupole) deformed nuclei, and for both together the dispersion of the scaled energies about the experimental values is about ±25%. This compares favorably with the performance of similar theories of the quadrupole excitations. Nuclei having static octupole deformations in HFB theory form a special category. These nuclei have the smallest measured octupole excitation energies as well as the smallest predicted energies. However, in these cases the energies are seriously underpredicted by the theory. We find that a simple two-configuration approximation, the minimization after projection (MAP) method, is almost as accurate as the full HW treatment, provided that the octupole-deformed nuclei are omitted from the comparison. This article is accompanied by a tabulation of the predicted octupole excitations for 818 nuclei extending from drip-line to drip-line, computed with several variants of the Gogny interaction.

  4. Trapping and manipulation of isolated atoms using nanoscale plasmonic structures.

    PubMed

    Chang, D E; Thompson, J D; Park, H; Vuletić, V; Zibrov, A S; Zoller, P; Lukin, M D

    2009-09-18

    We propose and analyze a scheme to interface individual neutral atoms with nanoscale solid-state systems. The interface is enabled by optically trapping the atom via the strong near-field generated by a sharp metallic nanotip. We show that under realistic conditions, a neutral atom can be trapped with position uncertainties of just a few nanometers, and within tens of nanometers of other surfaces. Simultaneously, the guided surface plasmon modes of the nanotip allow the atom to be optically manipulated, or for fluorescence photons to be collected, with very high efficiency. Finally, we analyze the surface forces, heating and decoherence rates acting on the trapped atom.

  5. Evidence for octupole excitations in the odd-odd neutron-rich nucleus {sup 142}Cs

    SciTech Connect

    Liu, S. H.; Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.; Ma, W. C.; Daniel, A. V.; Ter-Akopian, G. M.

    2010-05-15

    High-spin states in the neutron-rich nucleus {sup 142}Cs are reinvestigated from a study of the spontaneous fission of {sup 252}Cf with the Gammasphere detector array. A new level scheme is built and spin-parities are assigned to levels based on angular correlation measurements and systematics. The new structure of {sup 142}Cs is proposed to be related to octupole correlations. The electric dipole moment of {sup 142}Cs is measured and a dramatic decrease of the dipole moments with increasing neutron numbers in the Cs isotopic chain is found.

  6. Ion trap array mass analyzer: structure and performance.

    PubMed

    Li, Xiaoxu; Jiang, Gongyu; Luo, Chan; Xu, Fuxing; Wang, Yuanyuan; Ding, Li; Ding, Chuan-Fan

    2009-06-15

    An ion trap array (ITA) mass analyzer--a novel ion trap mass analyzer with multiple ion trapping and analyzing channels--was designed and constructed. Its property and performance were investigated and reported in this paper. The ITA was built with several planar electrodes including two parallel printed circuit board (PCB) plates. Each PCB plate was fabricated to several identical rectangular electric strips based on normal PCB fabrication technology and was placed symmetrically to those on the opposite plate. There is no electrode between any two adjacent strips. Every strip was supplied with an rf voltage while the polarity of the voltage applied to the adjacent two strips was opposite. So the electric potential at the central plane between two adjacent strips is zero. Multiple identical electric field regions that contain the dominant quadrupole plus some other high-order fields were produced between the two PCB plates. The multiple identical electric field regions will have the property of ion trapping, ion storage, and mass analysis functions. So an ITA could work as multiple ion trap mass analyzers. It could perform multiple sample ion storage, mass-selected ion isolation, ion ejection, and mass analysis simultaneously. The ITA was operated at both "digital ion trap mode" and "conventional rf mode" experimentally. A preliminary mass spectrum has been carried out in one of the ion trap channels, and it shows a mass resolution of over 1000. Additional functions such as mass-selected ion isolation and mass-selected ion ejection have also been tested. Furthermore, the ITA has a small size and very low cost. An ITA with four channels is less than 30 cm(3) in total volume, and it shows a great promise for the miniaturization of the whole mass spectrometer instrument and high-throughput mass analysis. PMID:19441854

  7. Precise rainbow trapping for low-frequency acoustic waves with micro Mie resonance-based structures

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Yuan, Baoguo; Cheng, Ying; Liu, Xiaojun

    2016-02-01

    We have realized the acoustic rainbow trapping in the low frequency region (200-500 Hz) through micro Mie resonance-based structures. The structure has eight channels with a high refractive index obtained by coiling space, that can excite strong interactions with incident waves and support various orders of multipoles due to the Mie resonances of the microstructure. By utilizing the structure, the precise spatial modulation of the acoustic wave is demonstrated both theoretically and experimentally. The effect of trapping broadband acoustic waves and spatially separating different frequency components are ascribed to the monopolar Mie resonances of the structures. The trapping frequency is derived and the trapping positions can be tuned arbitrarily. With enhanced wave-structure interactions and tailored frequency responses, such micro structures show precise spectral-spatial control of acoustic waves and open a diverse venue for high performance acoustic wave detection, sensing, filtering, and a nondestructive test.

  8. Perfect light trapping in mid-IR using patterned ZnO structures (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Vangala, Shivashankar R.; Nader, Nima; Cleary, Justin W.; Guo, Junpeng; Leedy, Kevin D.; Hendrickson, Joshua R.

    2015-09-01

    Plasmonic assisted mid-IR light trapping using 1D grating structures patterned in Ga-ZnO is demonstrated. FDTD simulations of these structures with proper grating period and depth show the light trapping into a resonant mode resulting in a close to 100% reflection dip in the 4-8 µm wavelength regime. The 1D grating structures of different periods are fabricated using standard photolithography followed by etching. The resonant reflection dips in the experimentally measured spectra well agree with the FDTD simulation, exhibiting light trapping in the mid-IR as predicted.

  9. Coupling of nuclear quadrupole and octupole degrees of freedom in an angular momentum dependent potential of two deformation variables

    SciTech Connect

    Minkov, N.; Yotov, P.; Drenska, S.; Scheid, W.; Bonatsos, Dennis; Lenis, D.; Petrellis, D.

    2006-04-26

    We propose a collective rotation-vibration Hamiltonian of nuclei in which the axial quadrupole {beta}2 and octupole {beta}3 variables are coupled through the centrifugal interaction. We consider that the system oscillates between positive and negative {beta}3-values by rounding a potential core in the ({beta}2,{beta}3)- space. We examine the effect of the 'rounding' in the structure of the spectrum.

  10. Hyperfine-induced electric dipole contributions to the electric octupole and magnetic quadrupole atomic clock transitions

    NASA Astrophysics Data System (ADS)

    Dzuba, V. A.; Flambaum, V. V.

    2016-05-01

    Hyperfine-induced electric dipole contributions may significantly increase probabilities of otherwise very weak electric octupole and magnetic quadrupole atomic clock transitions (e.g., transitions between s and f electron orbitals). These transitions can be used for exceptionally accurate atomic clocks, quantum information processing, and the search for dark matter. They are very sensitive to new physics beyond the standard model, such as temporal variation of the fine-structure constant, the Lorentz invariance, and Einstein equivalence principle violation. We formulate conditions under which the hyperfine-induced electric dipole contribution dominates and perform calculations of the hyperfine structure and E3, M2 and the hyperfine-induced E1 transition rates for a large number of atoms and ions of experimental interest. Due to the hyperfine quenching the electric octupole clock transition in +173Yb is 2 orders of magnitude stronger than that in currently used +171Yb. Some enhancement is found in 13+143Nd, 14+149Pm, 14+147Sm, and 15+147Sm ions.

  11. Particle trapping: A key requisite of structure formation and stability of Vlasov–Poisson plasmas

    SciTech Connect

    Schamel, Hans

    2015-04-15

    Particle trapping is shown to control the existence of undamped coherent structures in Vlasov–Poisson plasmas and thereby affects the onset of plasma instability beyond the realm of linear Landau theory.

  12. How to assess light trapping structures versus a Lambertian Scatterer for solar cells?

    PubMed

    Schuster, Christian S; Bozzola, Angelo; Andreani, Lucio C; Krauss, Thomas F

    2014-03-10

    We propose a new figure of merit to assess the performance of light trapping nanostructures for solar cells, which we call the light trapping efficiency (LTE). The LTE has a target value of unity to represent the performance of an ideal Lambertian scatterer, although this is not an absolute limit but rather a benchmark value. Since the LTE aims to assess the nanostructure itself, it is, in principle, independent of the material, fabrication method or technology used. We use the LTE to compare numerous proposals in the literature and to identify the most promising light trapping strategies. We find that different types of photonic structures allow approaching the Lambertian limit, which shows that the light trapping problem can be approached from multiple directions. The LTE of theoretical structures significantly exceeds that of experimental structures, which highlights the need for theoretical descriptions to be more comprehensive and to take all relevant electro-optic effects into account.

  13. Highly efficient light-trapping structure design inspired by natural evolution.

    PubMed

    Wang, Chen; Yu, Shuangcheng; Chen, Wei; Sun, Cheng

    2013-01-01

    Recent advances in nanophotonic light trapping open up the new gateway to enhance the absorption of solar energy beyond the so called Yablonovitch Limit. It addresses the urgent needs in developing low cost thin-film solar photovoltaic technologies. However, current design strategy mainly relies on the parametric approach that is subject to the predefined topological design concepts based on physical intuition. Incapable of dealing with the topological variation severely constrains the design of optimal light trapping structure. Inspired by natural evolution process, here we report a design framework driven by topology optimization based on genetic algorithms to achieve a highly efficient light trapping structure. It has been demonstrated that the optimal light trapping structures obtained in this study exhibit more than 3-fold increase over the Yablonovitch Limit with the broadband absorption efficiency of 48.1%, beyond the reach of intuitive designs.

  14. Highly Efficient Light-Trapping Structure Design Inspired By Natural Evolution

    PubMed Central

    Wang, Chen; Yu, Shuangcheng; Chen, Wei; Sun, Cheng

    2013-01-01

    Recent advances in nanophotonic light trapping open up the new gateway to enhance the absorption of solar energy beyond the so called Yablonovitch Limit. It addresses the urgent needs in developing low cost thin-film solar photovoltaic technologies. However, current design strategy mainly relies on the parametric approach that is subject to the predefined topological design concepts based on physical intuition. Incapable of dealing with the topological variation severely constrains the design of optimal light trapping structure. Inspired by natural evolution process, here we report a design framework driven by topology optimization based on genetic algorithms to achieve a highly efficient light trapping structure. It has been demonstrated that the optimal light trapping structures obtained in this study exhibit more than 3-fold increase over the Yablonovitch Limit with the broadband absorption efficiency of 48.1%, beyond the reach of intuitive designs. PMID:23289067

  15. Neutron-Rich Nuclei Beyond {sup 132}Sn: Spherical Shapes and Octupole Correlations

    SciTech Connect

    Liu Shaohua; Hamilton, Joseph H.; Ramayya, Akunuri V.; Goodin, Christopher T.; Hwang, Jae-Kwang; Luo Yixiao; Rasmussen, John O.; Covello, Aldo; Gargano, Angel; Stone, Nick J.; Daniel, Andrey V.; Ter-Akopian, Gurgen M.; Oganessian, Yuri Ts.; Zhu Shengjiang

    2010-04-30

    Nuclear properties of nuclei with a few valence nucleons outside the doubly-magic {sup 132}Sn core and located in the octupole correlation region have been investigated via gamma-gamma-gamma coincidence measurements of prompt gamma-ray emitted in the spontaneous fission of {sup 252}Cf with Gammasphere. The high spin level scheme of {sup 134}I has been identified for the first time. Shell model calculations reproduce the level scheme quite well. The level schemes of {sup 137}I and {sup 139}Cs have been reinvestigated and extended. Their nuclear structure is well described by realistic shell model calculations. The g-factors of the 4{sup +} state in {sup 134}Te, 15/2{sup +} state in {sup 135}I, and 15/2{sup -} state in {sup 137}Xe were determined using a newly developed program for angular correlation analysis. The measured g-factors compared favorably with shell model calculations. Octupole correlations are proposed in {sup 141}Cs and {sup 142}Cs. The variations of D{sub 0} in the Cs isotopes exhibit a pronounced drop of dipole moment with increasing neutron number.

  16. EPR spin trapping and DFT studies on structure of active antioxidants in biogycerol

    NASA Astrophysics Data System (ADS)

    Jerzykiewicz, Maria; Ćwieląg-Piasecka, Irmina; Witwicki, Maciej; Jezierski, Adam

    2010-09-01

    Spin trapping EPR spectroscopy and DFT methods were used to investigate the structure of antioxidants present in bioglycerols [glycerol fractions (GF) derived from biodiesel production]. For this purpose the reactions of GF components and their pure reference chemicals with PBN and H 2O 2 were examined via EPR measurements. The EPR parameters of formed PBN spin adducts indicated the α-tocopherol origin of the trapped radicals. The comparative analysis of experimental and theoretically calculated hyperfine constants for the spin adducts strongly suggests the carbon-centered nature of the radicals generated and trapped by PBN in the bioglycerol systems.

  17. Shallow seismic trapping structure in the San Jacinto fault zone near Anza, California

    NASA Astrophysics Data System (ADS)

    Lewis, M. A.; Peng, Z.; Ben-Zion, Y.; Vernon, F. L.

    2005-09-01

    We analyse fault zone trapped waves, generated by ~500 small earthquakes, for high-resolution imaging of the subsurface structure of the Coyote Creek, Clark Valley and Buck Ridge branches of the San Jacinto fault zone near Anza, California. Based on a small number of selected trapped waves within this data set, a previous study concluded on the existence of a low-velocity waveguide that is continuous to a depth of 15-20 km. In contrast, our systematic analysis of the larger data set indicates a shallow trapping structure that extends only to a depth of 3-5 km. This is based on the following lines of evidence. (1) Earthquakes clearly outside these fault branches generate fault zone trapped waves that are recorded by stations within the fault zones. (2) A traveltime analysis of the difference between the direct S arrivals and trapped wave groups shows no systematic increase (moveout) with increasing hypocentral distance or event depth. Estimates based on the observed average moveout values indicate that the propagation distances within the low-velocity fault zone layers are 3-5 km. (3) Quantitative waveform inversions of trapped wave data indicate similar short propagation distances within the low-velocity fault zone layers. The results are compatible with recent inferences on shallow trapping structures along several other faults and rupture zones. The waveform inversions also indicate that the shallow trapping structures are offset to the northeast from the surface trace of each fault branch. This may result from a preferred propagation direction of large earthquake ruptures on the San Jacinto fault.

  18. Modeling of metal-ferroelectric-insulator-semiconductor structure considering the effects of interface traps

    NASA Astrophysics Data System (ADS)

    Sun, Jing; Shi, Xiao Rong; Zheng, Xue Jun; Tian, Li; Zhu, Zhe

    2015-06-01

    An improved model, in which the interface traps effects are considered, is developed by combining with quantum mechanical model, dipole switching theory and silicon physics of metal-oxide-semiconductor structure to describe the electrical properties of metal-ferroelectric-insulator-semiconductor (MFIS) structure. Using the model, the effects of the interface traps on the surface potential (ϕSi) of the semiconductor, the low frequency (LF) capacitance-voltage (C-V) characteristics and memory window of MFIS structure are simulated, and the results show that the ϕSi- V and LF C-V curves are shifted toward the positive-voltage direction and the memory window become worse as the density of the interface trap states increases. This paper is expected to provide some guidance to the design and performance improvement of MFIS structure devices. In addition, the improved model can be integrated into electronic design automation (EDA) software for circuit simulation.

  19. Ion Trapping, Storage, and Ejection in Structures for Lossless Ion Manipulations

    SciTech Connect

    Zhang, Xinyu; Garimella, Venkata BS; Prost, Spencer A.; Webb, Ian K.; Chen, Tsung-Chi; Tang, Keqi; Tolmachev, Aleksey V.; Norheim, Randolph V.; Baker, Erin Shammel; Anderson, Gordon A.; Ibrahim, Yehia M.; Smith, Richard D.

    2015-06-16

    A structure for lossless ion manipulation (SLIM) module was constructed with electrode arrays patterned on a pair of parallel printed circuit boards (PCB) separated by 5 mm and utilized to investigate capabilities for ion trapping at 4 Torr. Positive ions were confined by application of RF having alternating phases on a series of inner rung electrodes and by positive DC potentials on surrounding guard electrodes on each PCB. An axial DC field was also introduced by stepwise varying the DC potential of the inner rung electrodes so as to control the ion transport and accumulation inside the ion trap. We show that ions could be trapped and accumulated with 100% efficiency, stored for at least 5 hours with no losses, and could be rapidly ejected from the SLIM trap.

  20. Physical model for trap-assisted inelastic tunneling in metal-oxide-semiconductor structures

    NASA Astrophysics Data System (ADS)

    Jiménez-Molinos, F.; Palma, A.; Gámiz, F.; Banqueri, J.; López-Villanueva, J. A.

    2001-10-01

    A physical model for trap-assisted inelastic tunnel current through potential barriers in semiconductor structures has been developed. The model is based on the theory of multiphonon transitions between detrapped and trapped states and the only fitting parameters are those of the traps (energy level and concentration) and the Huang-Rhys factor. Therefore, dependences of the trapping and detrapping processes on the bias, position, and temperature can be obtained with this model. The results of the model are compared with experimental data of stress induced leakage current in metal-oxide-semiconductor devices. The average energy loss has been obtained and an interpretation is given of the curves of average energy loss versus oxide voltage. This allows us to identify the entrance of the assisted tunnel current in the Fowler-Nordheim regime. In addition, the dependence of the tunnel current and average energy loss on the model parameters has been studied.

  1. Length dependent folding kinetics of phenylacetylene oligomers: Structural characterization of a kinetic trap

    NASA Astrophysics Data System (ADS)

    Elmer, Sidney P.; Pande, Vijay S.

    2005-03-01

    Using simulation to study the folding kinetics of 20-mer poly-phenylacetylene (pPA) oligomers, we find a long time scale trapped kinetic phase in the cumulative folding time distribution. This is demonstrated using molecular dynamics to simulate an ensemble of over 100 folding trajectories. The simulation data are fit to a four-state kinetic model which includes the typical folded and unfolded states, along with an intermediate state, and most surprisingly, a kinetically trapped state. Topologically diverse conformations reminiscent of α helices, β turns, and sheets in proteins are observed, along with unique structures in the form of knots. The nonhelical conformations are implicated, on the basis of structural correlations to kinetic parameters, to contribute to the trapped kinetic behavior. The strong solvophobic forces which mediate the folding process and produce a stable helical folded state also serve to overstabilize the nonhelical conformations, ultimately trapping them. From our simulations, the folding time is predicted to be on the order of 2.5-12.5 μs in the presence of the trapped kinetic phase. The folding mechanism for these 20-mer chains is compared with the previously reported folding mechanism for the pPA 12-mer chains. A linear scaling relationship between the chain length and the mean first passage time is predicted in the absence of the trapped kinetic phase. We discuss the major implications of this discovery in the design of self-assembling nanostructures.

  2. Trapping phosphorus in runoff with a phosphorus removal structure.

    PubMed

    Penn, Chad J; McGrath, Joshua M; Rounds, Elliott; Fox, Garey; Heeren, Derek

    2012-01-01

    Reduction of phosphorus (P) inputs to surface waters may decrease eutrophication. Some researchers have proposed filtering dissolved P in runoff with P-sorptive byproducts in structures placed in hydrologically active areas with high soil P concentrations. The objectives of this study were to construct and monitor a P removal structure in a suburban watershed and test the ability of empirically developed flow-through equations to predict structure performance. Steel slag was used as the P sorption material in the P removal structure. Water samples were collected before and after the structure using automatic samples and analyzed for total dissolved P. During the first 5 mo of structure operation, 25% of all dissolved P was removed from rainfall and irrigation events. Phosphorus was removed more efficiently during low flow rate irrigation events with a high retention time than during high flow rate rainfall events with a low retention time. The six largest flow events occurred during storm flow and accounted for 75% of the P entering the structure and 54% of the P removed by the structure. Flow-through equations developed for predicting structure performance produced reasonable estimates of structure "lifetime" (16.8 mo). However, the equations overpredicted cumulative P removal. This was likely due to differences in pH, total Ca and Fe, and alkalinity between the slag used in the structure and the slag used for model development. This suggests the need for an overall model that can predict structure performance based on individual material properties.

  3. Octupole deformation in sup 221 Fr; E1 transition rates

    SciTech Connect

    Liang, C.F.; Peghaire, A. ); Sheline, R.K. )

    1990-07-10

    Experimental data following the alpha decay of{sup 225}Ac are interpreted in terms of a spectroscopy in {sup 221}Fr consistent with octupole deformation. However, the measured E1 transition probabilities suggest that the low lying bands in {sup 221}Fr are considerably more mixed than in nuclei with slightly higher mass number. It is suggested that this mixing of states in {sup 221}Fr is indicative of the partial collapse of Nilsson-like orbitals into more degenerate shell model orbitals.

  4. High. beta. studies in the Wisconsin Toroidal Octupole

    SciTech Connect

    Halle, J. H.; Kellman, A.; Post, R. S.; Prager, S. C.; Strait, E. J.; Zarnstorff, M. C.

    1980-09-01

    A wide range of MHD stable high ..beta.. plasmas is produced in the Wisconsin Levitated Octupole. At or near the single fluid regime we obtain, in the bad curvature region, ..beta.. = nk(T/sub e/ + T/sub i/)8..pi../B/sup 2/ approx. = 8%, twice the theoretical single fluid ballooning instability limit of 4%. We also obtain stable plasmas at ..beta.. approx. = 35%, 9 times the theoretical limit, in a regime in which both finite ion gyroradius and gyroviscosity effects are important.

  5. Structural and functional insights into Escherichia coli α2-macroglobulin endopeptidase snap-trap inhibition

    PubMed Central

    Garcia-Ferrer, Irene; Arêde, Pedro; Gómez-Blanco, Josué; Luque, Daniel; Duquerroy, Stephane; Castón, José R.; Goulas, Theodoros; Gomis-Rüth, F. Xavier

    2015-01-01

    The survival of commensal bacteria requires them to evade host peptidases. Gram-negative bacteria from the human gut microbiome encode a relative of the human endopeptidase inhibitor, α2-macroglobulin (α2M). Escherichia coli α2M (ECAM) is a ∼180-kDa multidomain membrane-anchored pan-peptidase inhibitor, which is cleaved by host endopeptidases in an accessible bait region. Structural studies by electron microscopy and crystallography reveal that this cleavage causes major structural rearrangement of more than half the 13-domain structure from a native to a compact induced form. It also exposes a reactive thioester bond, which covalently traps the peptidase. Subsequently, peptidase-laden ECAM is shed from the membrane and may dimerize. Trapped peptidases are still active except against very large substrates, so inhibition potentially prevents damage of large cell envelope components, but not host digestion. Mechanistically, these results document a novel monomeric “snap trap.” PMID:26100869

  6. Structural and functional insights into Escherichia coli α2-macroglobulin endopeptidase snap-trap inhibition.

    PubMed

    Garcia-Ferrer, Irene; Arêde, Pedro; Gómez-Blanco, Josué; Luque, Daniel; Duquerroy, Stephane; Castón, José R; Goulas, Theodoros; Gomis-Rüth, F Xavier

    2015-07-01

    The survival of commensal bacteria requires them to evade host peptidases. Gram-negative bacteria from the human gut microbiome encode a relative of the human endopeptidase inhibitor, α2-macroglobulin (α2M). Escherichia coli α2M (ECAM) is a ∼ 180-kDa multidomain membrane-anchored pan-peptidase inhibitor, which is cleaved by host endopeptidases in an accessible bait region. Structural studies by electron microscopy and crystallography reveal that this cleavage causes major structural rearrangement of more than half the 13-domain structure from a native to a compact induced form. It also exposes a reactive thioester bond, which covalently traps the peptidase. Subsequently, peptidase-laden ECAM is shed from the membrane and may dimerize. Trapped peptidases are still active except against very large substrates, so inhibition potentially prevents damage of large cell envelope components, but not host digestion. Mechanistically, these results document a novel monomeric "snap trap."

  7. Natural evolution inspired design of light trapping structure in thin film organic solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Yu, Shuangcheng; Chen, Wei; Sun, Cheng

    2013-09-01

    Light trapping has been developed to effectively enhance the efficiency of the thin film solar cell by extending the pathlength for light interacting with the active materials. Searching for optimal light trapping design requires a delicate balance among all the competing physical processes, including light refraction, reflection, and absorption. The existing design methods mainly depend on engineers' intuition to predefine the topology of the light-trapping structure. However, these methods are not capable of handling the topological variation in reaching the optimal design. In this work, a systematic approach based on Genetic Algorithm is introduced to design the scattering pattern for effective light trapping. Inspired by natural evolution, this method can gradually improve the performance of light trapping structure through iterative procedures, producing the most favorable structure with minimized reflection and substantial enhancement in light absorption. Both slot waveguide based solar cell and a more realistic organic solar with a scattering layer consisting of nano-scale patterned front layer is optimized to maximize absorption by strongly coupling incident sun light into the localized photonic modes supported by the multilayer system. Rigorous coupled wave analysis (RCWA) is implemented to evaluate the absorbance. The optimized slot waveguide cell achieves a broadband absorption efficiency of 48.1% and more than 3-fold increase over the Yablonovitch limit and the optimized realistic organic cell exhibits nearly 50% average absorbance over the solar spectrum with short circuit current density five times larger than the control case using planar ITO layer.

  8. Mobility-Selected Ion Trapping and Enrichment Using Structures for Lossless Ion Manipulations

    DOE PAGES

    Chen, Tsung-Chi; Ibrahim, Yehia M.; Webb, Ian K.; Garimella, Sandilya V. B.; Zhang, Xing; Hamid, Ahmed M.; Deng, Liulin; Karnesky, William E.; Prost, Spencer A.; Sandoval, Jeremy A.; et al

    2016-01-11

    The integration of ion mobility spectrometry (IMS) with mass spectrometry (MS) and the ability to trap ions in IMS-MS measurements is of great importance for performing reactions, accumulating ions, and increasing analytical measurement sensitivity. The development of Structures for Lossless Ion Manipulations (SLIM) offers the potential for ion manipulations in a more reliable and cost-effective manner, while opening opportunities for much more complex sequences of manipulations. Here, we demonstrate an ion separation and trapping module and a method based upon SLIM that consists of a linear mobility ion drift region, a switch/tee and a trapping region that allows the isolationmore » and accumulation of mobility-separated species. The operation and optimization of the SLIM switch/tee and trap are described and demonstrated for the enrichment of the low abundance ions. Lastly, we observed a linear increase in ion intensity with the number of trapping/accumulation events using the SLIM trap, illustrating its potential for enhancing the sensitivity of low abundance or targeted species.« less

  9. Laser trapping of radium for an electric dipole moment measurement

    NASA Astrophysics Data System (ADS)

    Mueller, P.; Sulai, I. A.; Trimble, W.; Ahmad, I.; Bailey, K.; Bishof, M.; Greene, J. P.; Guest, J. R.; Holt, R. J.; Lu, Z.-T.; O'Connor, T. P.; Gould, H. A.

    2008-05-01

    The best limits on time-reversal violation in the nuclear sector are currently set through electric dipole moment (EDM) searches on the neutron and Hg-199. Recent theoretical calculations predict that atomic EDM measurements of certain octupole-deformed nuclei, e.g., in the radium isotopic chain, are two to three orders of magnitude more sensitive to the underlying time-reversal violation than the one in Hg-199. Ra-225, with nuclear spin 1/2 and a radioactive half-life of 15 days, is a particularly attractive candidate for a tabletop EDM measurement based on a laser-cooling and trapping approach. Towards this end, we have successfully cooled and trapped atoms of Ra-225 and Ra-226 in a magneto-optical trap -- a first for this rare element -- and have identified black-body radiation as a beneficial source of optical repumping. We will present our laser cooling scheme and ongoing measurements of atomic level energies, lifetimes, isotope shifts and hyperfine structure in radium and discuss our progress towards an EDM measurement of Ra-225 based on an optical dipole trap. This work is supported by DOE, Office of Nuclear Physics, under contract No. DE-AC02-06CH11357.

  10. High-spin octupole yrast levels in {sup 216}Rn{sub 86}

    SciTech Connect

    Debray, M.E.; Davidson, J.; Davidson, M.; Kreiner, A. J.; Cardona, M. A.; Hojman, D.; Napoli, D.R.; De Angelis, G.; De Poli, M.; Gadea, A.; Lenzi, S.; Bazzacco, D.; Lunardi, S.; Rossi-Alvarez, C.; Ur, C.A.; Medina, N.

    2006-02-15

    The yrast level structure of {sup 216}Rn has been studied using in-beam spectroscopy {alpha}-{gamma}-{gamma} coincidence techniques through the {sup 208}Pb({sup 18}O, 2{alpha}2n) reaction in the 91-93 MeV energy range, using the 8{pi} GASP-ISIS spectrometer at Legnaro. The level scheme of {sup 216}Rn resulting from this study shows alternating parity bands only above a certain excitation energy. From this result, the lightest nucleus showing evidence of octupole collectivity at low spins is still {sup 216}Fr, thereby defining the lowest-mass corner for this kind of phenomenon as N{>=}129 and Z{>=}87.

  11. Novel Trapping and Scattering of Light in Resonant Nanophotonic Structures

    NASA Astrophysics Data System (ADS)

    Hsu, Chia Wei

    Nanophotonic structures provide unique ways to control light and alter its behaviors in ways not possible in macroscopic structures. In this thesis, we explore novel behaviors of light created by nanophotonic structures, with a common theme on resonance effects. The first half of the thesis focuses on a peculiar type of electromagnetic resonance, where the resonance lifetime diverges to infinity. These states, called bound states in the continuum, remain localized in space even though their frequency lie within a continuum of extended modes. We find such states in photonic crystal slabs and the surface of bulk photonic crystals. We show the conditions necessary for them to exist, and provide the first experimental observation of these unusual states. We also show that these states have a topological nature, with conserved and quantized topological charges that govern their generation, evolution, and annihilation. The second half of the thesis concerns light scattering from resonant nanophotonic structures, where resonances can enhance or suppress scattering at particular wavelengths and angles. We show that multiple resonances in one nanostructure and in the same multipole channel generally lead to a scattering dark state where the structure becomes transparent. Based on the coherent interference from multiple scatterers, we show there are geometries that can achieve a sharp structural color where the hue, saturation, and brightness are all viewing-angle independent. We also invent a new type of transparent display based on wavelength-selective light scattering from nanostructures.

  12. Advances in ion trap mass spectrometry: Photodissociation as a tool for structural elucidation

    SciTech Connect

    Stephenson, J.L. Jr.; Booth, M.M.; Eyler, J.R.; Yost, R.A.

    1995-12-01

    Photo-induced dissociation (PID) is the next most frequently used method (after collisional activation) for activation of Polyatomic ions in tandem mass spectrometry. The range of internal energies present after the photon absorption process are much narrower than those obtained with collisional energy transfer. Therefore, the usefulness of PID for the study of ion structures is greatly enhanced. The long storage times and instrumental configuration of the ion trap mass spectrometer are ideally suited for photodissociation experiments. This presentation will focus on both the fundamental and analytical applications of CO{sub 2} lasers in conjunction with ion trap mass spectrometry. The first portion of this talk will examine the fundamental issues of wavelength dependence, chemical kinetics, photoabsorption cross section, and collisional effects on photodissociation efficiency. The second half of this presentation will look at novel instrumentation for electrospray/ion trap mass spectrometry, with the concurrent development of photodissociation as a tool for structural elucidation of organic compounds and antibiotics.

  13. Structural, bioinformatic, and in vivo analyses of two Treponema pallidum lipoproteins reveal a unique TRAP transporter

    PubMed Central

    Deka, Ranjit K.; Brautigam, Chad A.; Goldberg, Martin; Schuck, Peter; Tomchick, Diana R.; Norgard, Michael V.

    2012-01-01

    Treponema pallidum, the bacterial agent of syphilis, is predicted to encode one tripartite ATP- independent periplasmic transporter (TRAP-T). TRAP-Ts typically employ a periplasmic substrate-binding protein (SBP) to deliver the cognate ligand to the transmembrane symporter. Herein, we demonstrate that the genes encoding the putative TRAP-T components from T. pallidum, tp0957 (the SBP) and tp0958 (the symporter) are in an operon with an uncharacterized third gene, tp0956. We determined the crystal structure of recombinant Tp0956; the protein is trimeric and perforated by a pore. Part of Tp0956 forms an assembly similar to those of “tetratricopeptide repeat” (TPR) motifs. The crystal structure of recombinant Tp0957 was also determined; like the SBPs of other TRAP-Ts, there are two lobes separated by a cleft. In these other SBPs, the cleft binds a negatively charged ligand. However, the cleft of Tp0957 has a strikingly hydrophobic chemical composition, indicating that its ligand may be substantially different and likely hydrophobic. Analytical ultracentrifugation of the recombinant versions of Tp0956 and Tp0957 established that these proteins associate avidly. This unprecedented interaction was confirmed for the native molecules using in vivo cross-linking experiments. Finally, bioinformatic analyses suggested that this transporter exemplifies a new subfamily of TPR-protein associated TRAP transporters (TPATs) that require the action of a TPR-containing accessory protein for the periplasmic transport of a potentially hydrophobic ligand(s). PMID:22306465

  14. Structural, Bioinformatic, and In Vivo Analyses of Two Treponema pallidum Lipoproteins Reveal a Unique TRAP Transporter

    SciTech Connect

    Deka, Ranjit K.; Brautigam, Chad A.; Goldberg, Martin; Schuck, Peter; Tomchick, Diana R.; Norgard, Michael V.

    2012-05-25

    Treponema pallidum, the bacterial agent of syphilis, is predicted to encode one tripartite ATP-independent periplasmic transporter (TRAP-T). TRAP-Ts typically employ a periplasmic substrate-binding protein (SBP) to deliver the cognate ligand to the transmembrane symporter. Herein, we demonstrate that the genes encoding the putative TRAP-T components from T. pallidum, tp0957 (the SBP), and tp0958 (the symporter), are in an operon with an uncharacterized third gene, tp0956. We determined the crystal structure of recombinant Tp0956; the protein is trimeric and perforated by a pore. Part of Tp0956 forms an assembly similar to those of 'tetratricopeptide repeat' (TPR) motifs. The crystal structure of recombinant Tp0957 was also determined; like the SBPs of other TRAP-Ts, there are two lobes separated by a cleft. In these other SBPs, the cleft binds a negatively charged ligand. However, the cleft of Tp0957 has a strikingly hydrophobic chemical composition, indicating that its ligand may be substantially different and likely hydrophobic. Analytical ultracentrifugation of the recombinant versions of Tp0956 and Tp0957 established that these proteins associate avidly. This unprecedented interaction was confirmed for the native molecules using in vivo cross-linking experiments. Finally, bioinformatic analyses suggested that this transporter exemplifies a new subfamily of TPATs (TPR-protein-associated TRAP-Ts) that require the action of a TPR-containing accessory protein for the periplasmic transport of a potentially hydrophobic ligand(s).

  15. Resonance of the Macromotion of Ions Trapped in a RF Trap by the Subharmonic Oscillation

    NASA Astrophysics Data System (ADS)

    Yoda, Jun; Sugiyama, Kazuhiko

    1992-11-01

    Yb+ ions were trapped in an uncompensated rf trap with light buffer gas and then the storage time, as well as the total number of the trapped ions, was determined by the rf resonance method. When the ratio of the frequency of the trapping field to that of the macromotion of the trapped ions was an integer, the total number and the storage time were smaller and shorter, respectively, than those obtained when the ratio was a half-integer. A theoretical calculation shows that this effect, called the subharmonic oscillation, is caused by excitation of the macromotion of the trapped ions by the leaked trapping rf field, in the case in which the ion trap has an octupole besides a quadrupole potential.

  16. Nuclear fusion as a probe for octupole deformation in 224Ra

    NASA Astrophysics Data System (ADS)

    Kumar, Raj; Lay, J. A.; Vitturi, A.

    2015-11-01

    Background: Nuclear fusion has been shown to be a useful probe to study the different nuclear shapes. However, the possibility of testing octupole deformation of a nucleus with this tool has not been fully explored yet. The presence of a static octupole deformation in nuclei will enhance a possible permanent electric dipole moment, leading to a possible demonstration of parity violation. Purpose: To check whether static octupole deformation and octupole vibration in fusion give different results so that both situations could be experimentally disentangled. Method: Fusion cross sections are computed in the coupled-channel formalism making use of the ingoing-wave boundary conditions (IWBC) for the systems 16O+144Ba and 16O+224Ra . Results: Barrier distributions of the two considered schemes show slightly different patterns. In the case of 144Ba, the difference between them is negligible. For the 224Ra case, perceptible differences are found in correspondence with its larger octupole deformation. However, the possibility of disentangling both schemes is not guaranteed and it will depend on the available experimental accuracy and the strength of the octupole deformation. Conclusions: The measurement of barrier distributions could be a complementary probe to support the presence of octupole deformation.

  17. Dynamic interfacial trapping of flexural waves in structured plates

    PubMed Central

    Craster, R. V.; Movchan, A. B.; Movchan, N. V.; Jones, I. S.

    2016-01-01

    The paper presents new results on the localization and transmission of flexural waves in a structured plate containing a semi-infinite two-dimensional array of rigid pins. In particular, localized waves are identified and studied at the interface boundary between the homogeneous part of the flexural plate and the part occupied by rigid pins. A formal connection has been made with the dispersion properties of flexural Bloch waves in an infinite doubly periodic array of rigid pins. Special attention is given to regimes corresponding to standing waves of different types as well as Dirac-like points that may occur on the dispersion surfaces. A single half-grating problem, hitherto unreported in the literature, is also shown to bring interesting solutions. PMID:27118892

  18. Structures of flagranones A, B and C, cyclohexenoxide antibiotics from the nematode-trapping fungus Duddingtonia flagrans.

    PubMed

    Anderson, M G; Rickards, R W; Lacey, E

    1999-11-01

    Spectroscopic data define the structures of the flagranones A (2), B (3) and C (4) from the nematode-trapping fungus Duddingtonia flagrans. These antibiotics are structurally related to the farnesylated cyclohexenoxides of the oligosporon group recently isolated from the nematode-trapping fungus Arthrobotrys oligospora, and show similar antimicrobial activity.

  19. Plasma resistivity measurements in the Wisconsin levitated octupole

    SciTech Connect

    Brouchous, D. A.

    1980-11-01

    Resistivity measurements parallel to the magnetic field were made on gun injected plasmas ranging in density from 10/sup 9/cm/sup -3/ to 10/sup 1/parallelcm/sup -3/ in the Wisconsin levitated octupole with toroidal and poloidal magnetic fields. The 10/sup 9/cm/sup -3/ plasma was collisionless with lambda/sub mfp/ > 100 mirror lengths, had T/sub e/ = 10 eV, T/sub i/ = 30 eV and was found to have anomalous resistivity scaling like eta = ..sqrt..T/sub e//n/sub e/ when E/sub parallel/ > E/su c/ is the Dreicer critical field. The 10/sup 12/cm/sup -3/ plasma was collisional with lambda/sub mfp/ < mirror length, had T/sub e/ = T/sub i/ approx. = .2 eV and was found to have Spitzer resistivity when E/sub parallel/ < E/sub c/.

  20. Structural evolution of the Permian-Triassic Cooper basin, Australia: Relation to hydrocarbon trap styles

    SciTech Connect

    Apak, S.N.; Stuart, W.J.; Lemon, N.M.; Wood, G.

    1997-04-01

    The structural and depositional history of the Cooper basin in eastern central Australia has revealed that the basin is a mildly compressional structural depression controlled by northwestrending and northeast-trending pre-Permian basement features. Pronounced pre-Permian compressions are indicated by northeast-trending major structures, the Gidgealpa-Merrimelia-Innamincka and Murteree-Nappacoongee trends. Detailed chronostratigraphic facies analysis, with closely spaced palynological control, of the Patchawarra Formation revealed that two pronounced phases of uplift occurred during the Sakmarian. The major intrabasin highs were rejuvenated during these tectonic events, as documented by crestal unconformities (middle and upper Patchawarra unconformities). Evidence of each event is dominantly tectonic in character, with similar depositional patterns over these highs related to each event. These events are also recognizable in midflank areas and basin margins with contemporaneous deposition in deeper parts of the basin. Results from this research show potential for future hydrocarbon discoveries within structural, stratigraphic, and structural/stratigraphic traps in the Cooper basin. Various trap styles are closely associated with faults, unconformities, and lateral facies changes. Lowside fault closures, onlap plays, and unconformity traps are expected to be well developed along intrabasinal highs, basin margins, and preexisting structures. The primary reservoir targets would be deltaic sequences comprising shoreline sandstones, distributary and delta-mouth bar deposits that may be well developed in synclinal areas, and flanks of intrabasin highs in the Copper basin.

  1. Secondary Fast Magnetoacoustic Waves Trapped in Randomly Structured Plasmas

    NASA Astrophysics Data System (ADS)

    Yuan, Ding; Li, Bo; Walsh, Robert W.

    2016-09-01

    Fast magnetoacoustic waves are an important tool for inferring parameters of the solar atmosphere. We numerically simulate the propagation of fast wave pulses in randomly structured plasmas that mimic the highly inhomogeneous solar corona. A network of secondary waves is formed by a series of partial reflections and transmissions. These secondary waves exhibit quasi-periodicities in both time and space. Since the temporal and spatial periods are related simply through the speed of the fast wave, we quantify the properties of secondary waves by examining the dependence of the average temporal period (\\bar{p}) on the initial pulse width (w 0) and studying the density contrast ({δ }ρ ) and correlation length (L c ) that characterize the randomness of the equilibrium density profiles. For small-amplitude pulses, {δ }ρ does not alter \\bar{p} significantly. Large-amplitude pulses, on the other hand, enhance the density contrast when {δ }ρ is small but have a smoothing effect when {δ }ρ is sufficiently large. We found that \\bar{p} scales linearly with L c and that the scaling factor is larger for a narrower pulse. However, in terms of the absolute values of \\bar{p}, broader pulses generate secondary waves with longer periods, and this effect is stronger in random plasmas with shorter correlation lengths. Secondary waves carry the signatures of both the leading wave pulse and the background plasma. Our study may find applications in magnetohydrodynamic seismology by exploiting the secondary waves detected in the dimming regions after coronal mass ejections or extreme ultraviolet waves.

  2. Disulfide Trapping for Modeling and Structure Determination of Receptor:Chemokine Complexes

    PubMed Central

    Kufareva, Irina; Gustavsson, Martin; Holden, Lauren G.; Qin, Ling; Zheng, Yi; Handel, Tracy M.

    2016-01-01

    Despite the recent breakthrough advances in GPCR crystallography, structure determination of protein-protein complexes involving chemokine receptors and their endogenous chemokine ligands remains challenging. Here we describe disulfide trapping, a methodology for generating irreversible covalent binary protein complexes from unbound protein partners by introducing two cysteine residues, one per interaction partner, at selected positions within their interaction interface. Disulfide trapping can serve at least two distinct purposes: (i) stabilization of the complex to assist structural studies, and/or (ii) determination of pairwise residue proximities to guide molecular modeling. Methods for characterization of disulfide-trapped complexes are described and evaluated in terms of throughput, sensitivity, and specificity towards the most energetically favorable cross-links. Due to abundance of native disulfide bonds at receptor:chemokine interfaces, disulfide trapping of their complexes can be associated with intramolecular disulfide shuffling and result in misfolding of the component proteins; because of this, evidence from several experiments is typically needed to firmly establish a positive disulfide crosslink. An optimal pipeline that maximizes throughput and minimizes time and costs by early triage of unsuccessful candidate constructs is proposed. PMID:26921956

  3. Cambrian-Ordovician Knox production in Ohio: Three case studies of structural-stratigraphic traps

    USGS Publications Warehouse

    Riley, R.A.; Wicks, J.; Thomas, Joan

    2002-01-01

    The Knox Dolomite (Cambrian-Ordovician) in Ohio consists of a mixed carbonate-siliciclastic sequence deposited in a tidal-flat to shallow-marine environment along a broad continental shelf. Knox hydrocarbon production occurs in porous sandstone and dolomite reservoirs in the Copper Ridge dolomite, Rose Run sandstone, and Beekmantown dolomite. In Ohio, historical Knox exploration and development have been focused on paleogeomorphic traps within the prolific Morrow Consolidated field, and more recently, within and adjacent to the Rose Run subcrop. Although these paleogeomorphic traps have yielded significant Knox production, structural and stratigraphic traps are being largely ignored. Three Knox-producing pools demonstrate structural and stratigraphic traps: the Birmingham-Erie pool in southern Erie and southwestern Lorain counties, the South Canaan pool in northern Wayne County, and the East Randolph pool in south-central Portage County. Enhanced porosity and permeability from fractures, as evident in the East Randolph pool, are also an underexplored mechanism for Knox hydrocarbon accumulation. An estimated 800 bcf of gas from undiscovered Knox resources makes the Knox one of the most attractive plays in the Appalachian basin.

  4. Simulations of octupole compensation of head-tail instability at the Tevatron

    SciTech Connect

    Meiqin Xiao; Tanaji Sen; Frank Schmidts

    2003-05-28

    The proton lifetime in the Tevatron depends sensitively on chromaticities. Too low chromaticities can make the beam unstable due to the weak head-tail instability. One way to compensate this effect is to introduce octupoles to create a larger amplitude dependent betatron tune spread. However, the use of octupoles will also introduce additional side effects such as second order chromaticity, differential tune shifts and chromaticities on both proton and anti-proton helices. The non-linear effects may also reduce the dynamic aperture. There are 67 octupoles in 4 different circuits in the Tevatron which may be used for this purpose. We report on a simulation study to find the best combinations of polarities and strengths of the octupoles.

  5. Description of nuclear octupole and quadrupole deformation close to axial symmetry: Octupole vibrations in the X(5) nuclei {sup 150}Nd and {sup 152}Sm

    SciTech Connect

    Bizzeti, P. G.; Bizzeti-Sona, A. M.

    2010-03-15

    The model, introduced in a previous paper, for the description of the octupole and quadrupole degrees of freedom in conditions close to the axial symmetry is used to describe the negative-parity band based on the first octupole vibrational state in nuclei close to the critical point of the U(5)-to-SU(3) phase transition. The situation of {sup 150}Nd and {sup 152}Sm is discussed in detail. The positive-parity levels of these nuclei, and also the in-band E2 transitions, are reasonably accounted for by the X(5) model. With simple assumptions on the nature of the octupole vibrations, it is also possible to describe the negative-parity sector with comparable accuracy without changing the description of the positive-parity part.

  6. Comparison between periodic and stochastic parabolic light trapping structures for thin-film microcrystalline Silicon solar cells.

    PubMed

    Peters, M; Battaglia, C; Forberich, K; Bläsi, B; Sahraei, N; Aberle, A G

    2012-12-31

    Light trapping is of very high importance for silicon photovoltaics (PV) and especially for thin-film silicon solar cells. In this paper we investigate and compare theoretically the light trapping properties of periodic and stochastic structures having similar geometrical features. The theoretical investigations are based on the actual surface geometry of a scattering structure, characterized by an atomic force microscope. This structure is used for light trapping in thin-film microcrystalline silicon solar cells. Very good agreement is found in a first comparison between simulation and experimental results. The geometrical parameters of the stochastic structure are varied and it is found that the light trapping mainly depends on the aspect ratio (length/height). Furthermore, the maximum possible light trapping with this kind of stochastic structure geometry is investigated. In a second step, the stochastic structure is analysed and typical geometrical features are extracted, which are then arranged in a periodic structure. Investigating the light trapping properties of the periodic structure, we find that it performs very similar to the stochastic structure, in agreement with reports in literature. From the obtained results we conclude that a potential advantage of periodic structures for PV applications will very likely not be found in the absorption enhancement in the solar cell material. However, uniformity and higher definition in production of these structures can lead to potential improvements concerning electrical characteristics and parasitic absorption, e.g. in a back reflector.

  7. Influence of the octupole mode on nuclear high-K isomeric properties

    NASA Astrophysics Data System (ADS)

    Minkov, Nikolay; Walker, Phil

    2014-05-01

    The influence of quadrupole-octupole deformations on the energy and magnetic properties of high-K isomeric states in even-even actinide (U, Pu, Cm, Fm, No), rare-earth (Nd, Sm and Gd), and superheavy (^{270}\\text{Ds}) nuclei is examined within a deformed shell model with pairing interaction. The neutron two-quasiparticle (2qp) isomeric energies and magnetic dipole moments are calculated over a wide range in the plane of quadrupole and octupole deformations. In most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation. At the same time, the calculations outline three different groups of nuclei: with pronounced, shallow, and missing minima in the 2qp energy surfaces with respect to the octupole deformation. The result indicates regions of nuclei with octupole softness as well as with possible octupole deformation in the high-K isomeric states. These findings show the need for further theoretical analysis as well as of detailed experimental measurements of magnetic moments in heavy deformed nuclei.

  8. Towards antihydrogen trapping and spectroscopy at ALPHA

    NASA Astrophysics Data System (ADS)

    Butler, E.; Andresen, G. B.; Ashkezari, M. D.; Baquero-Ruiz, M.; Bertsche, W.; Bowe, P. D.; Bray, C. C.; Cesar, C. L.; Chapman, S.; Charlton, M.; Fajans, J.; Friesen, T.; Fujiwara, M. C.; Gill, D. R.; Hangst, J. S.; Hardy, W. N.; Hayano, R. S.; Hayden, M. E.; Humphries, A. J.; Hydomako, R.; Jonsell, S.; Kurchaninov, L.; Lambo, R.; Madsen, N.; Menary, S.; Nolan, P.; Olchanski, K.; Olin, A.; Povilus, A.; Pusa, P.; Robicheaux, F.; Sarid, E.; Silveira, D. M.; So, C.; Storey, J. W.; Thompson, R. I.; van der Werf, D. P.; Wilding, D.; Wurtele, J. S.; Yamazaki, Y.

    2011-07-01

    Spectroscopy of antihydrogen has the potential to yield high-precision tests of the CPT theorem and shed light on the matter-antimatter imbalance in the Universe. The ALPHA antihydrogen trap at CERN's Antiproton Decelerator aims to prepare a sample of antihydrogen atoms confined in an octupole-based Ioffe trap and to measure the frequency of several atomic transitions. We describe our techniques to directly measure the antiproton temperature and a new technique to cool them to below 10 K. We also show how our unique position-sensitive annihilation detector provides us with a highly sensitive method of identifying antiproton annihilations and effectively rejecting the cosmic-ray background.

  9. Self-Trapping of Charge Carriers in Semiconducting Carbon Nanotubes: Structural Analysis.

    PubMed

    Adamska, Lyudmyla; Nazin, George V; Doorn, Stephen K; Tretiak, Sergei

    2015-10-01

    The spatial extent of charged electronic states in semiconducting carbon nanotubes with indices (6,5) and (7,6) was evaluated using density functional theory. It was observed that electrons and holes self-trap along the nanotube axis on length scales of about 4 and 8 nm, respectively, which localize cations and anions on comparable length scales. Self-trapping is accompanied by local structural distortions showing periodic bond-length alternation. The average lengthening (shortening) of the bonds for anions (cations) is expected to shift the G-mode frequency to lower (higher) values. The smaller-diameter nanotube has reduced structural relaxation due to higher carbon-carbon bond strain. The reorganization energy due to charge-induced deformations in both nanotubes is found to be in the 30-60 meV range. Our results represent the first theoretical simulation of self-trapping of charge carriers in semiconducting nanotubes, and agree with available experimental data. PMID:26722885

  10. Fabrication of the replica templated from butterfly wing scales with complex light trapping structures

    NASA Astrophysics Data System (ADS)

    Han, Zhiwu; Li, Bo; Mu, Zhengzhi; Yang, Meng; Niu, Shichao; Zhang, Junqiu; Ren, Luquan

    2015-11-01

    The polydimethylsiloxane (PDMS) positive replica templated twice from the excellent light trapping surface of butterfly Trogonoptera brookiana wing scales was fabricated by a simple and promising route. The exact SiO2 negative replica was fabricated by using a synthesis method combining a sol-gel process and subsequent selective etching. Afterwards, a vacuum-aided process was introduced to make PDMS gel fill into the SiO2 negative replica, and the PDMS gel was solidified in an oven. Then, the SiO2 negative replica was used as secondary template and the structures in its surface was transcribed onto the surface of PDMS. At last, the PDMS positive replica was obtained. After comparing the PDMS positive replica and the original bio-template in terms of morphology, dimensions and reflectance spectra and so on, it is evident that the excellent light trapping structures of butterfly wing scales were inherited by the PDMS positive replica faithfully. This bio-inspired route could facilitate the preparation of complex light trapping nanostructure surfaces without any assistance from other power-wasting and expensive nanofabrication technologies.

  11. Multiple trapping on a comb structure as a model of electron transport in disordered nanostructured semiconductors

    SciTech Connect

    Sibatov, R. T. Morozova, E. V.

    2015-05-15

    A model of dispersive transport in disordered nanostructured semiconductors has been proposed taking into account the percolation structure of a sample and joint action of several mechanisms. Topological and energy disorders have been simultaneously taken into account within the multiple trapping model on a comb structure modeling the percolation character of trajectories. The joint action of several mechanisms has been described within random walks with a mixture of waiting time distributions. Integral transport equations with fractional derivatives have been obtained for an arbitrary density of localized states. The kinetics of the transient current has been calculated within the proposed new model in order to analyze time-of-flight experiments for nanostructured semiconductors.

  12. Building spatially-structured biofilms with single-cell control using laser trapping

    NASA Astrophysics Data System (ADS)

    Rodesney, Christopher; Hutchison, Jaime; Kaushik, Karishma; Le, Henry; Hurwitz, Daniel; Irie, Yasuhiko; Gordon, Vernita

    2015-03-01

    Biofilms are sessile communities of microbes adhered to each other and to an interface. Biofilm infections are notoriously difficult to eradicate, and this arises in part from phenotypic changes due to the spatial structure of the biofilm. Spatial structure controls the microenvironment and intercellular associations, which in turn controls gene expression, virulence, and antibiotic resistance. There are few tools available for elucidating the role of spatial structure in biofilms. We present a method for controlling the positions of bacteria on a surface using optical trapping without impinging cell viability. Initial positions propagate into the developing biofilm, creating spatial structure. The native growth, motility, and surface adhesion of positioned cells are preserved, as shown for model organisms Pseudomonas aeruginosa and Staphylococcus aureus. We demonstrate statistically-significant effects of spatial structure on the growth of monoculture P. aeruginosa biofilms and for co-culture biofilms of P. aeruginosa and S. aureus. Because the laser trap we use is very basic and the other equipment required is inexpensive and standard, we believe that our technique will be a widely-usable tool for biological and physical collaborators at many types of institutions.

  13. Long-term Phanerozoic octupole fields and consequences for paleogeographic reconstructions

    NASA Astrophysics Data System (ADS)

    van der Voo, R.; Torsvik, T.

    2003-04-01

    The assumption that the ancient geomagnetic field was purely dipolar is fundamental to paleomagnetism. However, one sign that something may be amiss is that observed inclinations at mid-latitudes are often lower than expected. A zonal octupole field in the late Paleozoic, Mesozoic and Early Tertiary was revealed by comparing the observed paleomagnetic paleolatitude distributions for Laurussia (North America, Greenland, and Europe) with those predicted from the mean paleopoles. When only volcanics are analyzed, the pattern remains unchanged, indicating that inclination error in sediments is not the culprit. Estimates of the magnitude of the octupole/dipole field ratio center around 0.1, which could cause errors in conventional paleopoles of about 7.5 degrees; because of the antisymmetry of octupole fields a comparison of paleomagnetic poles from mid-northern and mid-southern hemisphere locations could thus be off by as much as 15 degrees. The well-known misfit between the paleomagnetic results from the Laurentia-European and Gondwana continents in a classical Pangea A configuration could be explained by such errors due to octupole fields. This explanation would negate the need to seek tectonic (Pangea B type) solutions for the misfit. Another misfit based on too-low inclinations is seen in a comparison of Central Asian poles with those for the Eurasian reference path, and here as well do octupole fields provide a possible solution, although sedimentary inclination shallowing is another possibility. When including Pre-Permian poles for Gondwana in a similar test for non-dipole fields, an increase in the percentage octupole contribution is suggested for older times. Undoubtedly, the octupole field contributions have varied in magnitude over shorter time scales as well.

  14. Transport mechanisms and charge trapping in thin dielectric/Si nano-crystals structures

    NASA Astrophysics Data System (ADS)

    De Salvo, B.; Ghibaudo, G.; Luthereau, P.; Baron, T.; Guillaumot, B.; Reimbold, G.

    2001-08-01

    In this work the transport mechanisms and charge trapping of novel dielectric systems based on semiconductor nano-crystals embedded in a dielectric matrix are studied. In particular, stacked films composed of a thin bottom dielectric (2-4 nm thick SiO2 or Si3N4), with an embedded two-dimensional (2-D) array of Si nano-crystals (obtained by low pressure chemical vapor deposition or by annealing of silicon rich oxide) and a thick top dielectric (8 nm-thick SiO2) are investigated. Gate leakage currents, at medium/high electric fields, are examined at temperatures varying between 77 and 473 K. Charge trapping phenomena, occurring at low electric fields, are studied as a function of the stressing gate voltage and the stressing time. Experimental results are explained by means of an elastic tunneling model, which takes into account the main structural characteristics of the Si-dots (size dispersion, density, spatial distribution) as well as the effect of trapped charges in the silicon nano-crystals.

  15. Community structure and diversity of tropical forest mammals: data from a global camera trap network.

    PubMed

    Ahumada, Jorge A; Silva, Carlos E F; Gajapersad, Krisna; Hallam, Chris; Hurtado, Johanna; Martin, Emanuel; McWilliam, Alex; Mugerwa, Badru; O'Brien, Tim; Rovero, Francesco; Sheil, Douglas; Spironello, Wilson R; Winarni, Nurul; Andelman, Sandy J

    2011-09-27

    Terrestrial mammals are a key component of tropical forest communities as indicators of ecosystem health and providers of important ecosystem services. However, there is little quantitative information about how they change with local, regional and global threats. In this paper, the first standardized pantropical forest terrestrial mammal community study, we examine several aspects of terrestrial mammal species and community diversity (species richness, species diversity, evenness, dominance, functional diversity and community structure) at seven sites around the globe using a single standardized camera trapping methodology approach. The sites-located in Uganda, Tanzania, Indonesia, Lao PDR, Suriname, Brazil and Costa Rica-are surrounded by different landscape configurations, from continuous forests to highly fragmented forests. We obtained more than 51 000 images and detected 105 species of mammals with a total sampling effort of 12 687 camera trap days. We find that mammal communities from highly fragmented sites have lower species richness, species diversity, functional diversity and higher dominance when compared with sites in partially fragmented and continuous forest. We emphasize the importance of standardized camera trapping approaches for obtaining baselines for monitoring forest mammal communities so as to adequately understand the effect of global, regional and local threats and appropriately inform conservation actions. PMID:21844049

  16. Sediment storage dam: A structural gully erosion control and sediment trapping measure, northern Ethiopia

    NASA Astrophysics Data System (ADS)

    Mekonnen, Mulatie; Keesstra, Saskia; Baartman, Jantiene; Ritsema, Coen

    2014-05-01

    Gully erosion is a prime problem in Ethiopia. This study assessed the severity of gully erosion and the role of sediment storage dams (SSD) in restoring gullies and preventing further gully development, its sediment trapping efficacy (STE) and its capacity in converting degraded gully lands to productive land. On average 2.5 m deep, 6.6 m wide and 28.3 m long gullies were formed in Minizr watershed, northwest Ethiopia, in 2013. Concentrated surface runoff, traditional ditches, graded terraces without suitable water ways and road construction are the main causes of such serious gully erosion. Over grazing, tunnel flow and lack of proper immediate gully treatment actions after gully initiation are found to be additional causes of the problem. Gully erosion was also found as the major source of sediment for downstream rivers and water reservoirs. The annual volume of soil eroded from only four gullies was 1941.3 m3. To control gully erosion, SSDs were found to be important physical structures, which can trap significant amount of sediment within gullies and they can convert unproductive gully land to productive agricultural land for fruit and crop production. Eight SSDs trapped about 44*103 m3 of sediment within 2 to 8 years. Two representative SSDs constructed using gabion and stone were tested for their STE. Results showed that their efficacy was 74.1% and 66.4% for the gabion and stone SSDs, respectively. Six of the older SSDs were already full of sediment and created 0.75 ha of productive land within 2 to 8 years. SSDs best fits to treat large size and deep gullies where other gully control measures, check dams, could not function well. To prevent gully formation, controlling its causes that is avoiding traditional ditches, practicing grassed water ways to safely remove runoff water from graded terraces, integrated watershed and road side management practices are important solutions. KEY WORDS: Sediment storage dam, gully erosion, sediment trapping efficacy

  17. Coulomb structures of charged macroparticles in static magnetic traps at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Vasiliev, M. M.; Petrov, O. F.; Statsenko, K. B.

    2015-12-01

    Electrically charged (up to 107 e) macroscopic superconducting particles with sizes in the micrometer range confined in a static magnetic trap in liquid nitrogen and in nitrogen vapor at temperatures of 77-91 K are observed experimentally. The macroparticles with sizes up to 60 μm levitate in a nonuniform static magnetic field B ~ 2500 G. The formation of strongly correlated structures comprising as many as ~103 particles is reported. The average particle distance in these structures amounts to 475 μm. The coupling parameter and the Lindemann parameter of these structures are estimated to be ~107 and ~0.03, respectively, which is characteristic of strongly correlated crystalline or glasslike structures.

  18. Buried structural traps in upper paleozoic strata of the Orenburg region and their petroleum prospects. [USSR

    SciTech Connect

    Orel, A.V.

    1982-07-01

    Analysis of drilling data within the Orenburg sector of the northern marginal zone of the Caspian Basin and the Sol'-Ilets rise has shown that horizons of the Moscovian Stage of Late Carboniferous and Early Permian age rest on an eroded surface of Bashkirian deposits in a transgressive succession.Changes in thicknesses in the upper Paleozoic stratigraphic complexes indicate a significant discordance between the structural plans of the Artinskian and Bashkirian deposits and the possibility of discovering buried traps here, promising in the search for oil and gas.

  19. Time structure of postmidnight energetic electron precipitation and the limit of stable trapping

    NASA Technical Reports Server (NTRS)

    Trefall, H.; Williams, D. J.

    1979-01-01

    The paper examines the detailed time structure of high-energy (over 30 keV) electron precipitation along the morningside and dayside of the auroral zone. To this end, available high time resolution data from the Ogo 6 energetic electron experiment are analyzed. The relationship between trapped flux levels and degree of precipitation observed is studied from an observational standpoint and compared with the critical flux levels estimated by Kennel and Petschek (1966). A possible explanation within the general framework of the Kennel-Petschek theory of the observed burstlike precipitation episodes is presented, and the implications of these features for the average lifetime of electrons in drifting clouds are discussed.

  20. Plasmonic light trapping in an ultrathin photovoltaic layer with film-coupled metamaterial structures

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Wang, Liping

    2015-02-01

    A film-coupled metamaterial structure is numerically investigated for enhancing the light absorption in an ultrathin photovoltaic layer of crystalline gallium arsenide (GaAs). The top subwavelength concave grating and the bottom metallic film could not only effectively trap light with the help of wave interference and magnetic resonance effects excited above the bandgap, but also practically serve as electrical contacts for photon-generated charge collection. The energy absorbed by the active layer is greatly enhanced with the help of the film-coupled metamaterial structure, resulting in significant improvement on the short-circuit current density by three times over a free-standing GaAs layer at the same thickness. The performance of the proposed light trapping structure is demonstrated to be little affected by the grating ridge width considering the geometric tolerance during fabrication. The optical absorption at oblique incidences also shows direction-insensitive behavior, which is highly desired for efficiently converting off-normal sunlight to electricity. The results would facilitate the development of next-generation ultrathin solar cells with lower cost and higher efficiency.

  1. Molecular structure of monomorphic peptide fibrils within a kinetically trapped hydrogel network

    PubMed Central

    Nagy-Smith, Katelyn; Moore, Eric; Schneider, Joel; Tycko, Robert

    2015-01-01

    Most, if not all, peptide- and protein-based hydrogels formed by self-assembly can be characterized as kinetically trapped 3D networks of fibrils. The propensity of disease-associated amyloid-forming peptides and proteins to assemble into polymorphic fibrils suggests that cross-β fibrils comprising hydrogels may also be polymorphic. We use solid-state NMR to determine the molecular and supramolecular structure of MAX1, a de novo designed gel-forming peptide, in its fibrillar state. We find that MAX1 adopts a β-hairpin conformation and self-assembles with high fidelity into a double-layered cross-β structure. Hairpins assemble with an in-register Syn orientation within each β-sheet layer and with an Anti orientation between layers. Surprisingly, although the MAX1 fibril network is kinetically trapped, solid-state NMR data show that fibrils within this network are monomorphic and most likely represent the thermodynamic ground state. Intermolecular interactions not available in alternative structural arrangements apparently dictate this monomorphic behavior. PMID:26216960

  2. Escherichia coli and Candida albicans Induced Macrophage Extracellular Trap-Like Structures with Limited Microbicidal Activity

    PubMed Central

    Liao, Chengshui; Liu, Xiaolei; Du, Jing; Shi, Haining; Wang, Xuelin; Bai, Xue; Peng, Peng; Yu, Lu; Wang, Feng; Zhao, Ying; Liu, Mingyuan

    2014-01-01

    The formation of extracellular traps (ETs) has recently been recognized as a novel defense mechanism in several types of innate immune cells. It has been suggested that these structures are toxic to microbes and contribute significantly to killing several pathogens. However, the role of ETs formed by macrophages (METs) in defense against microbes remains little known. In this study, we demonstrated that a subset of murine J774A.1 macrophage cell line (8% to 17%) and peritoneal macrophages (8.5% to 15%) form METs-like structures (METs-LS) in response to Escherichia coli and Candida albicans challenge. We found only a portion of murine METs-LS, which are released by dying macrophages, showed detectable killing effects on trapped E. coli but not C. albicans. Fluorescence and scanning electron microscopy analyses revealed that, in vitro, both microorganisms were entrapped in J774A.1 METs-LS composed of DNA and microbicidal proteins such as histone, myeloperoxidase and lysozyme. DNA components of both nucleus and mitochondrion origins were detectable in these structures. Additionally, METs-LS formation occurred independently of ROS produced by NADPH oxidase, and this process did not result in cell lysis. In summary, our results emphasized that microbes induced METs-LS in murine macrophage cells and that the microbicidal activity of these METs-LS differs greatly. We propose the function of METs-LS is to contain invading microbes at the infection site, thereby preventing the systemic diffusion of them, rather than significantly killing them. PMID:24587206

  3. Plasmonic light trapping in an ultrathin photovoltaic layer with film-coupled metamaterial structures

    SciTech Connect

    Wang, Hao; Wang, Liping

    2015-02-15

    A film-coupled metamaterial structure is numerically investigated for enhancing the light absorption in an ultrathin photovoltaic layer of crystalline gallium arsenide (GaAs). The top subwavelength concave grating and the bottom metallic film could not only effectively trap light with the help of wave interference and magnetic resonance effects excited above the bandgap, but also practically serve as electrical contacts for photon-generated charge collection. The energy absorbed by the active layer is greatly enhanced with the help of the film-coupled metamaterial structure, resulting in significant improvement on the short-circuit current density by three times over a free-standing GaAs layer at the same thickness. The performance of the proposed light trapping structure is demonstrated to be little affected by the grating ridge width considering the geometric tolerance during fabrication. The optical absorption at oblique incidences also shows direction-insensitive behavior, which is highly desired for efficiently converting off-normal sunlight to electricity. The results would facilitate the development of next-generation ultrathin solar cells with lower cost and higher efficiency.

  4. Search for the two-phonon octupole vibrational state in {sup 208}Pb

    SciTech Connect

    Blumenthal, D.J.; Henning, W.; Janssens, R.V.F.

    1995-08-01

    We performed an experiment to search for the two-phonon octupole vibrational state in {sup 208}Pb. Thick targets of {sup 208}Pb, {sup 209}Bi, {sup 58,64}Ni, and {sup 160}Gd were bombarded with 1305 MeV beams of were bombard {sup 208}Pb supplied by ATLAS. Gamma rays were detected using the Argonne-Notre Dame BGO gamma-ray facility, consisting of 12 Compton-suppressed germanium detectors surrounding an array of 50 BGO scintillators. We identified some 30 known gamma rays from {sup 208}Pb in the spectra gated by the 5{sup -} {yields} 3{sup -} and 3{sup -} {yields} 0{sup +} transitions in {sup 208}Pb. In addition, after unfolding these spectra for Compton response, we observed broad coincident structures in the energy region expected for the 2-phonon states. Furthermore, we confirmed the placement of a 2485 keV line observed previously in {sup 207}Pb and find no evidence consistent with the placement of this line in {sup 208}Pb. We are currently in the process of investigating the origin of the broadened lines observed in the spectra, extracting the excitation probability of states in {sup 208}Pb, and determining the relative probability of mutual excitation and neutron transfer in this reaction. An additional experiment is also being performed to collect much higher statistics germanium-germanium coincidence data for the thick {sup 208}Pb target.

  5. Search for stable octupole deformation in the nucleus /sup 225/Fr

    SciTech Connect

    Burke, D.G.; Kurcewicz, W.; Loevhoeiden, G.; Nyboe, K.; Thorsteinsen, T.F.; Gietz, H.; Kaffrell, N.; Rogowski, J.; Naumann, R.A.; Borge, M.J.G.; and others

    1987-12-10

    The level structure of /sup 225/Fr has been studied from the /sup 225/Rn(..beta../sup -/) decay in on-line experiments at the ISOLDE facility. A level scheme was constructed on the basis of gamma--gamma coincidence data, and the multipolarities of many transitions were established by conversion electron measurements. Levels in /sup 225/Fr were also studied with the /sup 226/Ra(t,..cap alpha..)/sup 225/Fr reaction at the McMaster University Accelerator Laboratory, using a target of /sup 226/Ra(T/sub 1/2/ = 1600y) and a magnetic spectrograph to analyze the alpha spectra. The first three excited states, at 28.5, 82.5 and 128.2 keV, are interpreted as rotational band members based on the ground state, which is known to have I = 3/2. The (t,..cap alpha..) strengths to these levels indicate a 3/2/sup -/(532) assignment to the ground state. No evidence for an octupole deformation in /sup 225/Fr has been found so far, although analysis of data for other excited states is continuing.

  6. Entropy-driven structural transition and kinetic trapping in formamidinium lead iodide perovskite

    PubMed Central

    Chen, Tianran; Foley, Benjamin J.; Park, Changwon; Brown, Craig M.; Harriger, Leland W.; Lee, Jooseop; Ruff, Jacob; Yoon, Mina; Choi, Joshua J.; Lee, Seung-Hun

    2016-01-01

    A challenge of hybrid perovskite solar cells is device instability, which calls for an understanding of the perovskite structural stability and phase transitions. Using neutron diffraction and first-principles calculations on formamidinium lead iodide (FAPbI3), we show that the entropy contribution to the Gibbs free energy caused by isotropic rotations of the FA+ cation plays a crucial role in the cubic-to-hexagonal structural phase transition. Furthermore, we observe that the cubic-to-hexagonal phase transition exhibits a large thermal hysteresis. Our first-principles calculations confirm the existence of a potential barrier between the cubic and hexagonal structures, which provides an explanation for the observed thermal hysteresis. By exploiting the potential barrier, we demonstrate kinetic trapping of the cubic phase, desirable for solar cells, even at 8.2 K by thermal quenching.

  7. Electron trapping in evolving coronal structures during a large gradual hard X-ray/radio burst

    NASA Technical Reports Server (NTRS)

    Bruggmann, G.; Vilmer, N.; Klein, K.-L.; Kane, S. R.

    1994-01-01

    Gradual hard X-ray/radio bursts are characterized by their long duration, smooth time profile, time delays between peaks at different hard X-ray energies and microwaves, and radiation from extended sources in the low and middle corona. Their characteristic properties have been ascribed to the dynamic evolution of the accelerated electrons in coronal magnetic traps or to the separate acceleration of high-energy electrons in a 'second step' process. The information available so far was drawn from quality considerations of time profiles or even only from the common occurrence of emissions in different spectral ranges. This paper presents model computations of the temporal evolution of hard X-ray and microwave spectra, together with a qualitative discussion of radio lightcurves over a wide spectral range, and metric imaging observations. The basis hypothesis investigated is that the peculiar 'gradual' features can be related to the dynamical evolution of electrons injected over an extended time interval in a coronal trap, with electrons up to relativistic energies being injected simultaneously. The analyzed event (26 April. 1981) is particularly challenging to this hypothesis because of the long time delays between peaks at different X-ray energies and microwave frequencies. The observations are shown to be consistent with the hypothesis, provided that the electrons lose their energy by Coulomb collisions and possibly betatron deceleration. The access of the electrons to different coronal structures varies in the course of the event. The evolution and likely destabilization of part of the coronal plasma-magnetic field configuration is of crucial influence in determining the access to these structures and possibly the dynamical evolution of the trapped electrons through betatron deceleration in the late phase of the event.

  8. Percolation mechanism through trapping/de-trapping process at defect states for resistive switching devices with structure of Ag/SixC1-x/p-Si

    NASA Astrophysics Data System (ADS)

    Liu, Yanhong; Gao, Ping; Jiang, Xuening; Li, La; Zhang, Jialiang; Peng, Wei

    2014-08-01

    Pure SixC1-x (x > 0.5) and B-containing SixC1-x (x > 0.5) based resistive switching devices (RSD) with the structure of Ag/SixC1-x/p-Si were fabricated and their switching characteristics and mechanism were investigated systematically. Percolation mechanism through trapping/ de-trapping at defect states was suggested for the switching process. Through the introduction of B atoms into SixC1-x, the density of defect states was reduced, then, the SET and RESET voltages were also decreased. Based on the percolation theory, the dependence of SET/RESET voltage on the density of defect states was analyzed. These results supply a deep understanding for the SiC-based RSD, which have a potential application in extreme ambient conditions.

  9. Modeling giant structural traps in the Perdido fold belt, Gulf of Mexico

    SciTech Connect

    Trudgill, B.D.; Rowan, M.G.; Fiduk, J.C.; Weimer, P. )

    1996-01-01

    The Perdido fold belt in the Alaminos Canyon OCS protraction area contains some of the largest, untested structural traps within US waters. The overall structural geometry of the fold belt is relatively simple, although individual structures show a complex array of structural styles. Previous interpretations have modeled these structures as either growth fault-bend folds or salt-cored detachment folds. Structural interpretation of high quality 2D seismic data, combined with detailed analysis of the growth strata and both 2D and 3D restorations provides the necessary control to model these structures accurately. The 2D restorations show that the observed geometries of then folds and their growth strata are compatible with a detachment fold model. The folds developed due to gravitational gliding above, and at the basinward limit of, a thick layer of autochthonous salt. The growth strata indicate a relatively short period of folding and uplift during the late Oligocene to early Miocene. 3D restorations of an anomalous, dome-shaped structure suggest it formed due to interference between an elongate, NE-SW trending anticline and a NW-SE trending basement feature. The real test of our restorations, and the viability of the Perdido fold belt as a petroleum province remains to be tested by exploratory drilling.

  10. Antimatter Plasmas in a Multipole Trap for Antihydrogen

    SciTech Connect

    Andresen, G.; Bowe, P. D.; Hangst, J. S.; Bertsche, W.; Chapman, S.; Deutsch, A.; Fajans, J.; Povilus, A.; Wurtele, J. S.; Boston, A.; Chartier, M.; Nolan, P.; Cesar, C. L.; Silveira, D. M.; Charlton, M.; Jenkins, M. J.; Joergensen, L. V.; Madsen, N.; Telle, H. H.; Werf, D. P. van der

    2007-01-12

    We have demonstrated storage of plasmas of the charged constituents of the antihydrogen atom, antiprotons and positrons, in a Penning trap surrounded by a minimum-B magnetic trap designed for holding neutral antiatoms. The neutral trap comprises a superconducting octupole and two superconducting, solenoidal mirror coils. We have measured the storage lifetimes of antiproton and positron plasmas in the combined Penning-neutral trap, and compared these to lifetimes without the neutral trap fields. The magnetic well depth was 0.6 T, deep enough to trap ground state antihydrogen atoms of up to about 0.4 K in temperature. We have demonstrated that both particle species can be stored for times long enough to permit antihydrogen production and trapping studies.

  11. Antimatter plasmas in a multipole trap for antihydrogen.

    PubMed

    Andresen, G; Bertsche, W; Boston, A; Bowe, P D; Cesar, C L; Chapman, S; Charlton, M; Chartier, M; Deutsch, A; Fajans, J; Fujiwara, M C; Funakoshi, R; Gill, D R; Gomberoff, K; Hangst, J S; Hayano, R S; Hydomako, R; Jenkins, M J; Jørgensen, L V; Kurchaninov, L; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Robicheaux, F; Sarid, E; Silveira, D M; Storey, J W; Telle, H H; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2007-01-12

    We have demonstrated storage of plasmas of the charged constituents of the antihydrogen atom, antiprotons and positrons, in a Penning trap surrounded by a minimum-B magnetic trap designed for holding neutral antiatoms. The neutral trap comprises a superconducting octupole and two superconducting, solenoidal mirror coils. We have measured the storage lifetimes of antiproton and positron plasmas in the combined Penning-neutral trap, and compared these to lifetimes without the neutral trap fields. The magnetic well depth was 0.6 T, deep enough to trap ground state antihydrogen atoms of up to about 0.4 K in temperature. We have demonstrated that both particle species can be stored for times long enough to permit antihydrogen production and trapping studies.

  12. Shell Structure, Melting and Dynamics of Ion Clusters Confined in an Octupolar Trap

    SciTech Connect

    Calvo, F.; Yurtsever, E.

    2009-12-03

    The stable structures of clusters of identical ions trapped in an isotropic octupolar trap are investigated using global optimization methods. These clusters form well defined shells of ions that are approximately solutions of the Thomson problem. In particular, magic numbers are found to correlate with highly symmetric configurations. Using Monte Carlo simulations, finite temperature properties are also investigated. Melting proceeds from the core, and takes place through a very progressive loss of the shell structure. The hollow shape is eventually lost at very high temperatures, where the ions essentially feel the confinement but not the Coulomb repulsion. The vibrational density of states shows marked differences with the harmonic case, but also with bulk Wigner crystals. The variations of the maximal Lyapunov exponent obtained from additional molecular dynamics trajectories reveals that the dynamics becomes increasingly chaotic as the temperature increases. With the decreasing influence of the Coulomb interaction, a more regular behavior is found at very high temperatures but, contrary to the quadrupolar case, still highly chaotic.

  13. Possible octupole deformation in Cs and Ba nuclei from their differential radii

    SciTech Connect

    Sheline, R.K.; Jain, A.K.; Jain, K.

    1988-12-01

    The odd-even staggering of the differential radii of Fr and Ra and the Cs and Ba nuclei is compared. This staggering is inverted in the region of known octupole deformation in the Fr and Ra nuclei. The normal staggering is eliminated in the Cs nuclei and attenuated in the Ba nuclei for neutron numbers 85--88. This fact is used to suggest the possible existence of octupole deformation and its neutron number range in the Cs and Ba nuclear ground states.

  14. Influence of octupole interactions on the behavior of negative-parity states at low spins

    SciTech Connect

    Sitdikov, A. S. Safarov, R. Kh.; Kvasil, J.

    2006-12-15

    The energies of negative-parity levels based on two-particle states exhibit a nonlinear behavior at low spins versus the core-rotation energy because the alignment process has not yet been completed for them. This behavior of negative-parity levels in the low-spin region is satisfactorily described upon the inclusion of octupole-octupole interactions. This is demonstrated within the rotational model involving the Coriolis mixing of states for the even-even isotopes {sup 162-168}Hf.

  15. Time-dependent Hartree-Fock Study of Octupole Vibrations in doubly magic nuclei

    NASA Astrophysics Data System (ADS)

    Simenel, C.; Buete, J.; Vo-Phuoc, K.

    2016-09-01

    Octupole vibrations are studied in some doubly magic nuclei using the time-dependent Hartree-Fock (TDHF) theory with a Skyrme energy density functional. Through the use of the linear response theory, the energies and transition amplitudes of the low-lying vibrational modes for each of the nuclei were determined. Energies were found to be close to experimental results. However, transition amplitudes, quantified by the deformation parameter β3, are underestimated by TDHF. A comparison with single-particle excitations on the Hartree-Fock ground-state shows that the collective octupole vibrations have their energy lowered due to attractive RPA residual interaction.

  16. Specifications of the octupole magnets required for the ATF2 ultra-low ß* lattice

    SciTech Connect

    Marin, E.; Modena, M.; Tauchi, T.; Terunuma, N.; Tomas, R.; White, G.R.; /SLAC

    2014-05-28

    The Accelerator Test Facility 2 (ATF2) aims to test the novel chromaticity correction for higher chromaticity lattices as the one of CLIC. To this end the ATF2 ultra-low ß* lattice is designed to vertically focus the beam at the focal point or usually referred to as interaction point (IP), down to 23 nm. However when the measured multipole components of the ATF2 magnets are considered in the simulations, the evaluated spot sizes at the IP are well above the design value. The designed spot size is effectively recovered by inserting a pair of octupole magnets. In this note we address the technical specifications required for these octupole magnets.

  17. Application of linker technique to trap transiently interacting protein complexes for structural studies

    PubMed Central

    Reddy Chichili, Vishnu Priyanka; Kumar, Veerendra; Sivaraman, J.

    2016-01-01

    Protein-protein interactions are key events controlling several biological processes. We have developed and employed a method to trap transiently interacting protein complexes for structural studies using glycine-rich linkers to fuse interacting partners, one of which is unstructured. Initial steps involve isothermal titration calorimetry to identify the minimum binding region of the unstructured protein in its interaction with its stable binding partner. This is followed by computational analysis to identify the approximate site of the interaction and to design an appropriate linker length. Subsequently, fused constructs are generated and characterized using size exclusion chromatography and dynamic light scattering experiments. The structure of the chimeric protein is then solved by crystallization, and validated both in vitro and in vivo by substituting key interacting residues of the full length, unlinked proteins with alanine. This protocol offers the opportunity to study crucial and currently unattainable transient protein interactions involved in various biological processes. PMID:26985443

  18. Structural features of northern Tarim basin: Implications for regional tectonics and petroleum traps

    SciTech Connect

    Dong Jia; Juafu Lu; Dongsheng Cai

    1998-01-01

    The rhombus-shaped Tarim basin in northwestern China is controlled mainly by two left-lateral strike-slip systems: the northeast-trending Altun fault zone along its southeastern side and the northeast-trending Aheqi fault zone along its northwestern side. In this paper, we discuss the northern Tarim basin`s structural features, which include three main tectonic units: the Kalpin uplift, the Kuqa depression, and the North Tarim uplift along the northern margin of the Tarim basin. Structural mapping in the Kalpin uplift shows that a series of imbricated thrust sheets have been overprinted by strike-slip faulting. The amount of strike-slip displacement is estimated to be 148 km by restoration of strike-slip structures in the uplift. The Kuqa depression is a Mesozoic-Cenozoic foredeep depression with well-developed flat-ramp structures and fault-related folds. The Baicheng basin, a Quaternary pull-apart basin, developed at the center of the Kuqa depression. Subsurface structures in the North Tarim uplift can be divided into the Mesozoic-Cenozoic and the Paleozoic lithotectonic sequences in seismic profiles. The Paleozoic litho-tectonic sequence exhibits the interference of earlier left-lateral and later right-lateral strike-slip structures. Many normal faults in the Mesozoic-Cenozoic litho-tectonic sequence form the negative flower structures in the North Tarim uplift; these structures commonly directly overlie the positive flower structures in the Paleozoic litho-tectonic sequence. The interference regions of the northwest-trending and northeast-trending folds in the Paleozoic tectonic sequence have been identified to have the best trap structures. Our structural analysis indicates that the Tarim basin is a transpressional foreland basin rejuvenated during the Cenozoic.

  19. Antihydrogen Trapped

    NASA Astrophysics Data System (ADS)

    Bowe[1], Paul

    2011-05-01

    In 2010 the ALPHA collaboration succeeded in trapping antihydrogen atoms for the first time. Stored antihydrogen promises to be a unique tool for making high precision measurements of the structure of this first anti-atom. Achieving this milestone presented several substantial experimental challenges and this talk will describe how they were overcome. The unique design features of the ALPHA apparatus will be explained. These allow a high intensity positron source and an antiproton imaging detector similar to the one used in the ATHENA experiment to be combined with an innovative magnet design of the anti-atom trap. This seeks to minimise the perturbations to trapped charged particles which may cause particle loss and heating. The diagnostic techniques used to measure the diameter, number, density, and temperatures of both plasmas will be presented as will the methods developed to actively compress and cool of both plasma species to sizes and temperatures,, where trapping attempts with a reasonable chance of success can be tried. The results of the successful trapping experiments will be outlined as well as some subsequent experiments to improve the trapping rate and storage time.

  20. Structure of cyclin G-associated kinase (GAK) trapped in different conformations using nanobodies

    PubMed Central

    Chaikuad, Apirat; Keates, Tracy; Vincke, Cécile; Kaufholz, Melanie; Zenn, Michael; Zimmermann, Bastian; Gutiérrez, Carlos; Zhang, Rong-guang; Hatzos-Skintges, Catherine; Joachimiak, Andrzej; Muyldermans, Serge; Herberg, Friedrich W.; Knapp, Stefan; Müller, Susanne

    2014-01-01

    GAK (cyclin G-associated kinase) is a key regulator of clathrin-coated vesicle trafficking and plays a central role during development. Additionally, due to the unusually high plasticity of its catalytic domain, it is a frequent ‘off-target’ of clinical kinase inhibitors associated with respiratory side effects of these drugs. In the present paper, we determined the crystal structure of the GAK catalytic domain alone and in complex with specific single-chain antibodies (nanobodies). GAK is constitutively active and weakly associates in solution. The GAK apo structure revealed a dimeric inactive state of the catalytic domain mediated by an unusual activation segment interaction. Co-crystallization with the nanobody NbGAK_4 trapped GAK in a dimeric arrangement similar to the one observed in the apo structure, whereas NbGAK_1 captured the activation segment of monomeric GAK in a well-ordered conformation, representing features of the active kinase. The presented structural and biochemical data provide insight into the domain plasticity of GAK and demonstrate the utility of nanobodies to gain insight into conformational changes of dynamic molecules. In addition, we present structural data on the binding mode of ATP mimetic inhibitors and enzyme kinetic data, which will support rational inhibitor design of inhibitors to reduce the off-target effect on GAK. PMID:24438162

  1. Structured inquiry-based learning: Drosophila GAL4 enhancer trap characterization in an undergraduate laboratory course.

    PubMed

    Dunne, Christopher R; Cillo, Anthony R; Glick, Danielle R; John, Katherine; Johnson, Cody; Kanwal, Jaspinder; Malik, Brian T; Mammano, Kristina; Petrovic, Stefan; Pfister, William; Rascoe, Alexander S; Schrom, Diane; Shapiro, Scott; Simkins, Jeffrey W; Strauss, David; Talai, Rene; Tomtishen, John P; Vargas, Josephine; Veloz, Tony; Vogler, Thomas O; Clenshaw, Michael E; Gordon-Hamm, Devin T; Lee, Kathryn L; Marin, Elizabeth C

    2014-12-01

    We have developed and tested two linked but separable structured inquiry exercises using a set of Drosophila melanogaster GAL4 enhancer trap strains for an upper-level undergraduate laboratory methods course at Bucknell University. In the first, students learn to perform inverse PCR to identify the genomic location of the GAL4 insertion, using FlyBase to identify flanking sequences and the primary literature to synthesize current knowledge regarding the nearest gene. In the second, we cross each GAL4 strain to a UAS-CD8-GFP reporter strain, and students perform whole mount CNS dissection, immunohistochemistry, confocal imaging, and analysis of developmental expression patterns. We have found these exercises to be very effective in teaching the uses and limitations of PCR and antibody-based techniques as well as critical reading of the primary literature and scientific writing. Students appreciate the opportunity to apply what they learn by generating novel data of use to the wider research community.

  2. Crystal Structures of EF-G-Ribosome Complexes Trapped in Intermediate States of Translocation

    SciTech Connect

    Zhou, Jie; Lancaster, Laura; Donohue, John Paul; Noller, Harry F.

    2013-11-12

    Translocation of messenger and transfer RNA (mRNA and tRNA) through the ribosome is a crucial step in protein synthesis, whose mechanism is not yet understood. The crystal structures of three Thermus ribosome-tRNA-mRNA–EF-G complexes trapped with β,γ-imidoguanosine 5'-triphosphate (GDPNP) or fusidic acid reveal conformational changes occurring during intermediate states of translocation, including large-scale rotation of the 30S subunit head and body. In all complexes, the tRNA acceptor ends occupy the 50S subunit E site, while their anticodon stem loops move with the head of the 30S subunit to positions between the P and E sites, forming chimeric intermediate states. Two universally conserved bases of 16S ribosomal RNA that intercalate between bases of the mRNA may act as “pawls” of a translocational ratchet. These findings provide new insights into the molecular mechanism of ribosomal translocation.

  3. Structure formation in immiscible two-species Bose-Einstein condensates in perturbed harmonic traps

    NASA Astrophysics Data System (ADS)

    Pattinson, Robert; Parker, Nick; Proukakis, Nick; Liu, I.-Kang; Gou, Shih-Chuan; Gardiner, Simon; McCarron, Daniel; Cho, Hung-Wen; Cornish, Simon; Billam, Tom

    2013-05-01

    We investigate the mean-field equilibrium solutions for a trapped two-species 87Rb-133Cs immiscible Bose-Einstein condensate, and show that the density profiles observed in a recent Bose-Einstein experiment (D. J. McCarron et al. Phys. Rev. A 84, 011603 (2011)), which include ball and shell formations and axially/radially separated states, can be reproduced when accounting for weak linear perturbations. We also demonstrate the importance of the coupled growth of the two condensates by a simple finite temperature model which reveals such structures to be generally metastable in the presence of dissipation, with our findings confirmed by the more accurate Stochastic Projected Gross-Pitaevskii equation.

  4. Time-resolved soft-x-ray spectroscopy of a magnetic octupole transition in nickel-like xenon, cesium, and barium ions

    SciTech Connect

    Trabert, E; Beiersdorfer, P; Brown, G V; Boyce, K; Kelley, R L; Kilbourne, C A; Porter, F S; Szymkowiak, A

    2005-11-11

    A microcalorimeter with event mode capability for time-resolved soft-x-ray spectroscopy, and a high-resolution flat-field EUV spectrometer have been employed at the Livermore EBIT-I electron beam ion trap for observations and wavelength measurements of M1, E2, and M3 decays of long-lived levels in the Ni-like ions Xe{sup 26+}, Cs{sup 27+}, and Ba{sup 28+}. Of particular interest is the lowest excited level, 3d{sup 9}4s {sup 3}D{sub 3}, which can only decay via a magnetic octupole (M3) transition. For this level in Xe an excitation energy of (590.40 {+-} 0.03eV) and a level lifetime of (11.5 {+-} 0.5 ms) have been determined.

  5. Octupole deformation in 144,146Ba measured by Coulomb excitation of radioactive beams

    NASA Astrophysics Data System (ADS)

    Bucher, Brian; Zhu, Shaofei; ANL, LBNL, LLNL, Rochester, Florida State, Liverpool, Maryland, Notre Dame, Ohio, W. Scotland Collaboration

    2015-10-01

    The exotic, neutron-rich 144Ba (t1 / 2 = 11.5 s) and 146Ba (t1 / 2 = 2.2 s) nuclei are expected to exhibit some of the strongest octupole correlations in A < 200 systems. Up to now, evidence for such strong octupole correlations has been inferred from observations of low-lying negative-parity states and from the interleaving of positive- and negative-parity levels in the ground-state band. However, the E1 transition strengths are very different in these two nuclei, with two orders of magnitude reduction in 146Ba. In this experiment, we measure the octupole strength directly by Coulomb excitation of post-accelerated 144,146Ba beams produced at CARIBU using CHICO2 and GRETINA. In 144Ba, we found B(E3;3 -->0) = 48(-34+ 25) W.u., a value considerably larger than theoretical predictions, while preliminary results for 146Ba are also indicative of strong octupole collectivity. The experimental conditions, the analysis, and the results from these challenging new measurements will be presented. This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 (ANL), DE-AC02-05CH11231 (LBNL, GRETINA), DOE DE-AC52-07NA27344 (LLNL), and NSF.

  6. Direct evidence of octupole deformation in neutron-rich 144Ba

    DOE PAGES

    Bucher, B.; Zhu, S.; Wu, C. Y.; Janssens, R. V. F.; Cline, D.; Hayes, A. B.; Albers, M.; Ayangeakaa, A. D.; Butler, P. A.; Campbell, C. M.; et al

    2016-03-17

    Here, the neutron-rich nucleus 144Ba (t1/2 = 11.5 s) is expected to exhibit some of the strongest octupole correlations among nuclei with mass numbers A less than 200. Until now, indirect evidence for such strong correlations has been inferred from observations such as enhanced E1 transitions and interleaving positive- and negative-parity levels in the ground-state band. In this experiment, the octupole strength was measured directly by sub-barrier, multistep Coulomb excitation of a post-accelerated 650-MeV 144Ba beam on a 1.0–mg/cm2 208Pb target. The measured value of the matrix element, < 31–∥M(E3)∥01+ >= 0.65(+17–23) eb3/2, corresponds to a reduced B(E3) transition probabilitymore » of 48(+25–34) W.u. This result represents an unambiguous determination of the octupole collectivity, is larger than any available theoretical prediction, and is consistent with octupole deformation.« less

  7. Octupole Resonance in the AGS at High Intensity: A SIMBAD study

    SciTech Connect

    Luccio, A.U.; D'Imperio, N.L.

    2005-06-08

    We studied the Octupole (Montague) resonance in the AGS, in its high intensity mode, by tracking with the PIC code SIMBAD. We calculated, turn-by-turn, the betatron tune footprint from the eigenvalues of the one-turn matrix. We show that one should exercise particular caution when the betatron tunes are close together, since the matrix gives ambiguous results at the resonance.

  8. Formation and prediction of structural traps in northwest Beartooth Mountains near Livingston, Montana

    SciTech Connect

    Robbins, E.A.; Erslev, E.A.

    1986-08-01

    The bounding faults on the northeastern flank of the Beartooth Mountains display a reversal of thrust vergence, with southwest-dipping thrust faults in the southeast, and northeast-dipping thrust faults in the northwest. Previous structural models of the Beartooth uplift do not explain this reversal in vergence because they do not balance by sedimentary bed length or basement block area and are not restorable to conceivable initial geometries. In addition, the models do not account for the thin-skinned deformation exposed along the northwestern corner. Restorable models for the northwest Beartooth uplift predict a blind master thrust, dipping to the southwest with wedges of basement back thrust over the main block. The basement-wedge formation is probably responsible for complex thin-skinned thrusts, duplexes, and ramp structures that fill apparent strain incompatibilities (space problems) for the southeast and northwest corners of the uplift. Estimates of 8 to 14 km (5 to 7 mi) of upper crustal shortening are consistent with published estimates from gravity modeling to the southeast. Geometric balancing techniques that conserve basement area and sediment bed length provide strong constraints on the structural geometry of foreland uplifts in the Rocky Mountain region. In the Beartooth Mountains, the complex interplay between the postulated southwest-dipping master fault, northeast-dipping back thrusts, and thin-skinned deformation allow for multiple structural traps for petroleum accumulation. The surface exposures in the Beartooth Mountain uplift do not suggest the subsurface complexity predicted by the balanced cross sections.

  9. Extension-related structural traps in fault basins of eastern Nevada

    SciTech Connect

    Walker, C.T.; Dennis, J.G.; Lumsden, W.W.

    1989-04-01

    Low-angle younger-over-older faults have been widely reported in eastern Nevada, although no general agreement exists on their origin. Three preferred models are (1) local gravity sliding, (2) mid-crustal ductile extension, and (3) a master detachment possibly extending into the mantle. None are fully supported by field evidence. Some low-angle faults in the White Pine, Duck Creek and Schell Creek Ranges involve ductile extension along incompetent sedimentary units and brittle extension of intercalated competent units to form lenticular stretch structures. Upper crustal extension may be an indirect response to midcrustal ductile extension that occurred during a Tertiary heating event. Between the Duck Creek and Schell Creek Ranges, extension attenuated the pre-carboniferous section, creating a depression in which Carboniferous rocks were preserved. Since this structure, termed a pseudograben, can be traced northward into a typical graben, basins may be initiated by attenuation, with rifting occurring later. In such basins, subsurface detachments should be expected. Some low-angle faults resemble megalandslides because fragmented competent units slid into depressions created by attenuation. With retreat of the geotherms, ductile extension was confined to deep crustal levels and rifting replaced low-angle faulting at higher levels. Potential extension traps in basins are large-scale stretch structures, porous and permeable units truncated and sealed by detachment, and tilted blocks cut by steep faults. Best prospects are likely to occur in basins subjected only to Tertiary heating because oil generated at that time would be tapped in developing extension structures.

  10. Enhancing the absorption capabilities of thin-film solar cells using sandwiched light trapping structures.

    PubMed

    Abdellatif, S; Kirah, K; Ghannam, R; Khalil, A S G; Anis, W

    2015-06-10

    A novel structure for thin-film solar cells is simulated with the purpose of maximizing the absorption of light in the active layer and of reducing the parasitic absorption in other layers. In the proposed structure, the active layer is formed from an amorphous silicon thin film sandwiched between silicon nanowires from above and photonic crystal structures from below. The upper electrical contact consists of an indium tin oxide layer, which serves also as an antireflection coating. A metal backreflector works additionally as the other contact. The simulation was done using a new reliable, efficient and generic optoelectronic approach. The suggested multiscale simulation model integrates the finite-difference time-domain algorithm used in solving Maxwell's equation in three dimensions with a commercial simulation platform based on the finite element method for carrier transport modeling. The absorption profile, the external quantum efficient, and the power conversion efficiency of the suggested solar cell are calculated. A noticeable enhancement is found in all the characteristics of the novel structure with an estimated 32% increase in the total conversion efficiency over a cell without any light trapping mechanisms. PMID:26192857

  11. Superdeformed nuclei: Shells-vs-liquid drop, pairing-vs-thermal excitations, triaxial-vs-octupole shapes, super-superdeformation

    SciTech Connect

    Dudek, J.

    1987-01-01

    Mechanisms influencing the behavior of superdeformed nuclei are studied using several well established nuclear structure techniques. In particular: pairing, thermal excitation, shell and liquid-drop mechanisms are considered. The effects of quadrupole and hexadecapole (both axial and non-axial), and octupole deformation degrees of freedom are studied. Most of the results are illustrated using the case of /sup 152/Dy nucleus in which a superdeformed band extending up to I approx. 60 h-bar has been found in experiment. Some comparisons between /sup 152/Dy and the nuclei in the neighborhood are given. Calculations show that pairing ''de-aligns'' typically 6 to 8 units of angular momentum, as compared to the corresponding rigid rotation. This takes place for spins extending up to the highest limit, and thus diminishes the effective moments of inertia. Predicted octupole shape susceptibility is extremely large, significantly stronger than the susceptibilities known in the ground-states of many Actinide nuclei. Consequences of this result for the near-constancy of the dynamical moments of inertia are pointed out. Nuclear level densities calculated in function of spin, excitation energy and deformation explain the ''unusual'' side feeding pattern of the /sup 152/Dy superdeformed states. Predictions of super-superdeformed nuclear states (axis ratio varying between 2:1 and 3:1 or more) are given and exemplified for Erbium nuclei. Finally, the problem of superdeformation stability and the influence of increased collective inertia on a barrier penetration are examined. An analytical expression for the effective inertia parameter is obtained and its derivation outlined. 35 refs., 9 figs.

  12. Symmetry of the CMB sky as a new test of its statistical isotropy. Non cosmological octupole?

    SciTech Connect

    Naselsky, P.; Hansen, M.; Kim, J. E-mail: kirstejn@nbi.dk

    2011-09-01

    In this article we propose a novel test for statistical anisotropy of the CMB ΔT( n-circumflex = (θ,φ)). The test is based on the fact, that the Galactic foregrounds have a remarkably strong symmetry with respect to their antipodal points with respect to the Galactic plane, while the cosmological signal should not be symmetric or asymmetric under these transitions. We have applied the test for the octupole component of the WMAP ILC 7 map, by looking at a{sub 3,1} and a{sub 3,3}, and their ratio to a{sub 3,2} both for real and imaginary values. We find abnormal symmetry of the octupole component at the level of 0.58%, compared to Monte Carlo simulations. By using the analysis of the phases of the octupole we found remarkably strong cross-correlations between the phases of the kinematic dipole and the ILC 7 octupole, in full agreement with previous results. We further test the multipole range 2 < l < 100, by investigating the ratio between the l+m = even and l+m = odd parts of power spectra. We compare the results to simulations of a Gaussian random sky, and find significant departure from the statistically isotropic and homogeneous case, for a very broad range of multipoles. We found that for the most prominent peaks of our estimator, the phases of the corresponding harmonics are coherent with phases of the octupole. We believe, our test would be very useful for detections of various types of residuals of the foreground and systematic effects at a very broad range of multipoles 2 ≤ l ≤ 1500−3000 for the forthcoming PLANCK CMB map, before any conclusions about primordial non-Gaussianity and statistical anisotropy of the CMB.

  13. Characterization and FDTD simulation analysis on light trapping structures of amorphous silicon thin films by laser irradiation

    NASA Astrophysics Data System (ADS)

    Huang, Lu; Jin, Jing; Yuan, Zhijun; Yang, Weiguang; Wang, Linjun; Shi, Weimin; Zhou, Jun; Lou, Qihong

    2016-05-01

    The effect of laser energy density on the light-trapping structures of amorphous silicon (α-Si) thin films is studied both theoretically and experimentally. The thin films are irradiated by a frequency-doubled (λ = 532 nm) Nd:YAG pulsed nanosecond laser. An effective finite difference time domain (FDTD) model is built to find the optimized laser energy density (EL) for the light trapping structures of α-Si. Based on the simulation analysis, it shows the variation of reflection spectra with laser energy density. The optimized reflection spectra at EL = 1000 mJ/cm2 measured by UV-visible spectroscopy confirms to agree well with that corresponding to the depth to diameter ratio (h/D) in the FDTD simulation. The surface morphology characterization by optical microscope (OM) and scanning electron microscope (SEM) accords fairly well to of light-trapping modeling in the simulation.

  14. Stress influenced trapping processes in Si based multi-quantum well structures and heavy ions implanted Si

    SciTech Connect

    Ciurea, Magdalena Lidia Lazanu, Sorina

    2014-10-06

    Multi-quantum well structures and Si wafers implanted with heavy iodine and bismuth ions are studied in order to evaluate the influence of stress on the parameters of trapping centers. The experimental method of thermostimullatedcurrents without applied bias is used, and the trapping centers are filled by illumination. By modeling the discharge curves, we found in multilayered structures the parameters of both 'normal' traps and 'stress-induced' ones, the last having a Gaussian-shaped temperature dependence of the cross section. The stress field due to the presence of stopped heavy ions implanted into Si was modeled by a permanent electric field. The increase of the strain from the neighborhood of I ions to the neighborhood of Bi ions produces the broadening of some energy levels and also a temperature dependence of the cross sections for all levels.

  15. Chemical and Structural Analysis of an Antibody Folding Intermediate Trapped during Glycan Biosynthesis

    PubMed Central

    2012-01-01

    Human IgG Fc glycosylation modulates immunological effector functions such as antibody-dependent cellular cytotoxicity and phagocytosis. Engineering of Fc glycans therefore enables fine-tuning of the therapeutic properties of monoclonal antibodies. The N-linked glycans of Fc are typically complex-type, forming a network of noncovalent interactions along the protein surface of the Cγ2 domain. Here, we manipulate the mammalian glycan-processing pathway to trap IgG1 Fc at sequential stages of maturation, from oligomannose- to hybrid- to complex-type glycans, and show that the Fc is structurally stabilized following the transition of glycans from their hybrid- to complex-type state. X-ray crystallographic analysis of this hybrid-type intermediate reveals that N-linked glycans undergo conformational changes upon maturation, including a flip within the trimannosyl core. Our crystal structure of this intermediate reveals a molecular basis for antibody biogenesis and provides a template for the structure-guided engineering of the protein–glycan interface of therapeutic antibodies. PMID:23025485

  16. Crestal unconformities as indicators of clastic stratigraphic traps: genetic relation of Berlin field and Elk City structure, deep Anadarko basin

    SciTech Connect

    Lyday, J.R.

    1988-02-01

    The Berlin fan-delta gas reservoir in the deep Anardarko basin was deposited during the late Atokan (Pennsylvanian) as a response to the initial uplift and erosion of the Elk City structure. During the late Atokan pulse of the episodic Pennsylvanian orogeny in the south-central US, abrupt epeirogenic uplift and brittle deformation created an interregional unconformity on positive areas around foreland and cratonic basins. The Elk City structure within the deep Anadarko basin originated as a distinct, subaerially exposed upthrust-block during the late Atokan tectonic event. A crestal unconformity developed on the emergent upthrust block concurrent with its uplift. Terrigenous, detrital Atoka dolomite, originally sourced from the Arbuckle dolomite (Cambrian-Ordovician) of the Amarillo-Wichita uplift, was eroded from the upthrust block and recycled northward as the Berlin fan-delta. Today, the Berlin recrystallized, recycled detrital dolomite fan-delta is a large 41 mi/sup 2/ overpressured gas reservoir with 242-362 bcf reserves at 15,000 ft. The Berlin field is genetically related to the late Atokan crestal unconformity of the Elk City structure, and is an example of the association of crestal unconformities and clastic stratigraphic traps. Such stratigraphic traps originated in marine environments proximal to active structures that have become subaerially exposed. With adequate seals and favorable structural position, detrital deposits recycled from local uplifts can form significant stratigraphic traps. Such stratigraphic traps can occur in compressional, extensional, and diapiric regions.

  17. Morphing structures of the Dionaea muscipula Ellis during the trap opening and closing

    PubMed Central

    Volkov, Alexander G; Forde-Tuckett, Victoria; Volkova, Maya I; Markin, Vladislav S

    2014-01-01

    The Venus flytrap is a marvelous plant that has intrigued scientists since the times of Charles Darwin. This carnivorous plant is capable of very fast movements to catch a prey. We found that the maximal speed of the trap closing in the Dionaea muscipula Ellis is about 130 000 times faster than the maximal speed of the trap opening. The mechanism and kinetics of this movement was debated for a long time. Here, the most recent Hydroelastic Curvature Model is applied to the analysis of this movement during closing and opening of the trap with or without a prey. Equations describing the trap movement were derived and verified with experimental data. Chloroform and ether, both anesthetic agents, induce action potentials and close the trap without the mechanical stimulation of trigger hairs. We tested this by dropping 10 μL of ether on the midrib inside the trap without touching any of the mechanosensitive trigger hairs. The trap closed slowly in 10 s. This is at least 20 times slower than the closing of the trap mechanically or electrically. The similar effect can be induced by placing 10 μL of chloroform on the midrib inside the trap, however, the lobes closing time in this case is as fast as closing after mechanical stimulation of the trigger hairs. PMID:24618927

  18. Morphing structures of the Dionaea muscipula Ellis during the trap opening and closing.

    PubMed

    Volkov, Alexander G; Forde-Tuckett, Victoria; Volkova, Maya I; Markin, Vladislav S

    2014-01-01

    The Venus flytrap is a marvelous plant that has intrigued scientists since the times of Charles Darwin. This carnivorous plant is capable of very fast movements to catch a prey. We found that the maximal speed of the trap closing in the Dionaea muscipula Ellis is about 130,000 times faster than the maximal speed of the trap opening. The mechanism and kinetics of this movement was debated for a long time. Here, the most recent Hydroelastic Curvature Model is applied to the analysis of this movement during closing and opening of the trap with or without a prey. Equations describing the trap movement were derived and verified with experimental data. Chloroform and ether, both anesthetic agents, induce action potentials and close the trap without the mechanical stimulation of trigger hairs. We tested this by dropping 10 μL of ether on the midrib inside the trap without touching any of the mechanosensitive trigger hairs. The trap closed slowly in 10 s. This is at least 20 times slower than the closing of the trap mechanically or electrically. The similar effect can be induced by placing 10 μL of chloroform on the midrib inside the trap, however, the lobes closing time in this case is as fast as closing after mechanical stimulation of the trigger hairs.

  19. Can bioengineering structures made of willow cuttings trap sediment in eroded marly gullies in a Mediterranean mountainous climate?

    NASA Astrophysics Data System (ADS)

    Rey, Freddy; Burylo, Mélanie

    2014-01-01

    In the Southern French Alps, high sediment yields from marly catchments cause socio-economic and ecological problems downstream. Bioengineering structures made of willow cuttings could be used for efficient and sustainable sediment trapping in eroded gullies in order to decrease sediment yield at their outlets. However, little has been done to quantitatively assess the efficiency of such structures for trapping sediment or to improve their performance. The objectives of this study were to analyze the ability of bioengineering structures to enhance vegetation development and sediment trapping in marly gullies in the Southern French Alps, under a mountainous and Mediterranean climate. For five years after the restoration operations, we monitored 101 bioengineering structures using willow (Salix) cuttings, including 55 brush layers on wooden sills (BL) and 46 brush layers with brush mats on wooden sills (BLM), 1.2 m wide and 2 m long, installed on the floors of eight experimental marly gullies. The results showed that the ultimate survival of willow cuttings can be assessed after three years. Gully size and aspect appeared to be the most important factors influencing resprouting rates. By avoiding south-oriented gullies and those smaller than 1000 m2, 75% survival rates per structure may be achieved. The results also showed that BL trapped 0.18 m3 yr- 1 of sediment per structure on average and BLM 0.21 m3 yr- 1, but potential maximum values may reach 0.28 and 0.40 m3 yr- 1 over one year on BL and BLM, respectively. Therefore, bioengineering structures made of willow cuttings can be used to trap significant quantities of sediment from the first year onwards and efficiently restore eroded marly gullies under a Mediterranean mountainous climate. It also provides design criteria to guide future restoration actions and future investigations in the Southern French Alps.

  20. Trapping and amplification of quasi-longitudinal whistler wave in kinetic Alfvén wave localized structures

    NASA Astrophysics Data System (ADS)

    Rai, Rajesh Kumar; Sharma, Swati; Gaur, Nidhi; Sharma, R. P.

    2016-03-01

    In this work, we have studied the trapping of obliquely propagating (with respect to the ambient magnetic field) weak whistler wave due to inhomogeneity created by 3D kinetic Alfvén wave (KAW) in a magnetized plasma (magnetotail region). The nonlinearity arises due to ponderomotive effects associated with 3D KAW, consequently, the background density gets modified. The weak whistler wave propagating in this modified density gets either trapped or localized. The study has been carried out numerically and semi-analytically. The semi-analytical analysis show that the typical scale size of localized 3D KAW is of the order of ion gyroradius and that of the trapped whistler is even less than that. The relevance of the results is also pointed out in the context of the recent CLUSTER observations in magnetized plasmas where whistler waves have been detected along with coherent ion-scale magnetic structures.

  1. Extraterrestrial Helium (He@C60) Trapped in Fullerenes in the Sudbury Impact Structure

    NASA Technical Reports Server (NTRS)

    Becker, L.; Bada, J. L.; Poreda, R. J.; Bunch, T. E.

    1997-01-01

    Fullerenes (C60 and C70) have recently been identified in a shock-produced breccia (Onaping Formation) associated with the 1.85-Ga Sudbury Impact Crater. The presence of parts-per-million levels of fullerenes in this impact structure raises interesting questions about the processes that led to the formation of fullerenes and the potential for delivery of intact organic material to the Earth by a large bolide (e.g., asteroid or comet). Two possible scenarios for the presence of fullerenes in the Sudbury impact deposits are that (1) fullerenes are synthesized within the impact plume from the C contained in the bolide; or (2) fullerenes are already present in the bolide and survived the impact event. The correlation of C and trapped noble gas atoms in meteorites is well established. Primitive meteorites contain several trapped noble gas components that have anomalous isotopic compositions, some of which may have a presolar origin. Several C-bearing phases, including SiC, graphite, and diamond, have been recognized as carriers of trapped noble gases. It has also been suggested that fullerenes (C60 and C70) might be a carrier of noble gas components in carbonaceous chondrites. Recently, fullerenes have been detected in separate samples in the Allende meteorite. Carbon-60 is large enough to enclose the noble gases He, Ne, Ar, Kr, and Xe, but it is too small to contain diatomic gases such as N2 or triatomic gases such as CO2. Recent experimental work has demonstrated that noble gases of a specific isotopic composition can be introduced into synthetic fullerenes at high temperatures and pressures; these encapsulated gases can then be released by the breaking of one or more C bonds during step-heating under vacuum. These thermal-release patterns for He encapsulated within the C60 molecule (He@C60) are similar to the patterns for acid residues of carbonaceous chondrites, suggesting that fullerenes could be an additional carrier of trapped noble gases in acid residues of

  2. Artificially Structured Boundary For Antihydrogen Studies

    SciTech Connect

    Ordonez, C. A.

    2011-06-01

    It may be possible to confine antiprotons using an artificially structured boundary, as part of a process for synthesizing antihydrogen. An artificially structured boundary is defined at present as one that produces a spatially periodic static field, such that the spatial period and range of the field is much smaller than the dimensions of a cloud, plasma or beam of charged particles that is confined by the boundary. A modified Kingdon trap could employ an artificially structured boundary at the location of inner electrodes. The artificially structured boundary would produce a multipole magnetic field that keeps confined particles from reaching the inner electrodes. The magnetic field would be sufficiently short in range to affect the particle trajectories only in close proximity to the inner electrodes. The conditions for producing such a magnetic field have been assessed. The results indicate that the magnetic field must be an octupole or higher order field.

  3. Instability analysis of charges trapped in the oxide of metal-ultra thin oxide-semiconductor structures

    NASA Astrophysics Data System (ADS)

    Aziz, A.; Kassmi, K.; Maimouni, R.; Olivié, F.; Sarrabayrouse, G.; Martinez, A.

    2005-09-01

    In this paper, we present the theoretical and experimental results of the influence of a charge trapped in ultra-thin oxide of metal/ultra-thin oxide/semiconductor structures (MOS) on the I(Vg) current-voltage characteristics when the conduction is of the Fowler-Nordheim (FN) tunneling type. The charge, which is negative, is trapped near the cathode (metal/oxide interface) after constant current injection by the metal (Vg<0). Of particular interest is the influence on the Δ Vg(Vg) shift over the whole I(Vg) characteristic at high field (greater than the injection field (>12.5 MV/cm)). It is shown that the charge centroid varies linearly with respect to the voltage Vg. The behavior at low field (<12.5 MV/cm) is analyzed in référence A. Aziz, K. Kassmi, Ka. Kassmi, F. Olivié, Semicond. Sci. Technol. 19, 877 (2004) and considers that the trapped charge centroid is fixed. The results obtained make it possible to analyze the influence of the injected charge and the applied field on the centroid position of the trapped charge, and to highlight the charge instability in the ultra-thin oxide of MOS structures.

  4. Observation of structural relaxation during exciton self-trapping via excited-state resonant impulsive stimulated Raman spectroscopy

    SciTech Connect

    Mance, J. G.; Felver, J. J.; Dexheimer, S. L.

    2015-02-28

    We detect the change in vibrational frequency associated with the transition from a delocalized to a localized electronic state using femtosecond vibrational wavepacket techniques. The experiments are carried out in the mixed-valence linear chain material [Pt(en){sub 2}][Pt(en){sub 2}Cl{sub 2}]⋅(ClO{sub 4}){sub 4} (en = ethylenediamine, C{sub 2}H{sub 8}N{sub 2}), a quasi-one-dimensional system with strong electron-phonon coupling. Vibrational spectroscopy of the equilibrated self-trapped exciton is carried out using a multiple pulse excitation technique: an initial pump pulse creates a population of delocalized excitons that self-trap and equilibrate, and a time-delayed second pump pulse tuned to the red-shifted absorption band of the self-trapped exciton impulsively excites vibrational wavepacket oscillations at the characteristic vibrational frequencies of the equilibrated self-trapped exciton state by the resonant impulsive stimulated Raman mechanism, acting on the excited state. The measurements yield oscillations at a frequency of 160 cm{sup −1} corresponding to a Raman-active mode of the equilibrated self-trapped exciton with Pt-Cl stretching character. The 160 cm{sup −1} frequency is shifted from the previously observed wavepacket frequency of 185 cm{sup −1} associated with the initially generated exciton and from the 312 cm{sup −1} Raman-active symmetric stretching mode of the ground electronic state. We relate the frequency shifts to the changes in charge distribution and local structure that create the potential that stabilizes the self-trapped state.

  5. Universal, non-monotonic structure in the saturation curves of a linear Paul trap

    NASA Astrophysics Data System (ADS)

    Wells, James; Kwolek, Jonathan; Goodman, Douglas; Blümel, Reinhold; Smith, Winthrop

    2016-05-01

    A common technique to measure ion-atom collision rates in a hybrid trap if the ions have no optical transitions (e.g. alkalis) is to monitor the fluorescence of the neutrals in the presence of a saturated linear Paul trap (LPT). We present numerical simulations, analytical calculations, and experimental results that show that the steady-state ion capacity of an LPT, Ns, exhibits nonlinear, nonmonotonic behavior as a function of ion loading rate, Λ. The steady state as a function of loading rate, Ns(Λ) , shows four distinct regions. In Region I, at the lowest Λ, Ns(Λ) increases monotonically. Then, Ns(Λ) reaches a plateau in Region II, before decreasing to a local minimum in Region III. Finally, in Region IV, Ns(Λ) once again increases monotonically. This behavior appears universal to any Paul trap, regardless of geometry or species trapped. We examine this behavior experimentally as a function of the q stability parameter of the Paul trap and simulate numerically the effect of the particular trap geometry on the onset of each of the four regions. Funding from NSF Grant PHY-1307874.

  6. The nature of the TRAP-Anti-TRAP complex.

    PubMed

    Watanabe, Masahiro; Heddle, Jonathan G; Kikuchi, Kenichi; Unzai, Satoru; Akashi, Satoko; Park, Sam-Yong; Tame, Jeremy R H

    2009-02-17

    Tryptophan biosynthesis is subject to exquisite control in species of Bacillus and has become one of the best-studied model systems in gene regulation. The protein TRAP (trp RNA-binding attenuation protein) predominantly forms a ring-shaped 11-mer, which binds cognate RNA in the presence of tryptophan to suppress expression of the trp operon. TRAP is itself regulated by the protein Anti-TRAP, which binds to TRAP and prevents RNA binding. To date, the nature of this interaction has proved elusive. Here, we describe mass spectrometry and analytical centrifugation studies of the complex, and 2 crystal structures of the TRAP-Anti-TRAP complex. These crystal structures, both refined to 3.2-A resolution, show that Anti-TRAP binds to TRAP as a trimer, sterically blocking RNA binding. Mass spectrometry shows that 11-mer TRAP may bind up to 5 AT trimers, and an artificial 12-mer TRAP may bind 6. Both forms of TRAP make the same interactions with Anti-TRAP. Crystallization of wild-type TRAP with Anti-TRAP selectively pulls the 12-mer TRAP form out of solution, so the crystal structure of wild-type TRAP-Anti-TRAP complex reflects a minor species from a mixed population. PMID:19164760

  7. INFLUENCE OF FILM STRUCTURE AND LIGHT ON CHARGE TRAPPING AND DISSIPATION DYNAMICS IN SPUN-CAST ORGANIC THIN-FILM TRANSISTORS MEASURED BY SCANNING KELVIN PROBE MICROSCOPY

    SciTech Connect

    Teague, L.; Moth, M.; Anthony, J.

    2012-05-03

    Herein, time-dependent scanning Kelvin probe microscopy of solution processed organic thin film transistors (OTFTs) reveals a correlation between film microstructure and OTFT device performance with the location of trapped charge within the device channel. The accumulation of the observed trapped charge is concurrent with the decrease in I{sub SD} during operation (V{sub G}=-40 V, V{sub SD}= -10 V). We discuss the charge trapping and dissipation dynamics as they relate to the film structure and show that application of light quickly dissipates the observed trapped charge.

  8. Plasmonic optical trapping of metal nanoparticles for SERS by utilizing gold nano-ring structure

    NASA Astrophysics Data System (ADS)

    Kang, Zhiwen; Ho, Ho-Pui

    2012-10-01

    The derivate of surface plasmon and optical tweezers, so-called plasmonic nano-optical tweezers (PNOT), has attracted much research interest due to its powerful ability for immobilizing nano-objects in the nanoscale, and its potential application in chemo/biosensing and life science. In this work, we use gold nano-rings to construct PNOT, and demonstrate the feasibility to trap metal nanoparticles (Au-NPs) for SERS application from the numerical standpoint. 3D finite-difference time-domain (FDTD) and the Maxwell stress tensor (MST) were used in our simulation study. We show that the interactions of the localized surface plasmon (LSP) excitation and the plasmonic interferences of the nano-ring arrays contribute to a narrow spectral feature around 785 nm, resulting in strong local near-field enhancement and thus intensive field gradient forces. The trapping potential well is as high as 1.31×10-19 J under a low illuminating power density of 1.0 mW/μm2, which makes the trapping events effective enough to overcome Brownian motion of the Au-NPs. Moreover, the existence of multiple potential wells results in a very large active volume of ~106 nm3 for trapping the target particles. The trapped Au-NPs further lead to the formation of nano-gaps that offer a field enhancement of 160 times. Our proposal shows promising applications for sensing and microfluidic integrations.

  9. A differentially pumped dual linear quadrupole ion trap (DLQIT) mass spectrometer: a mass spectrometer capable of MS(n) experiments free from interfering reactions.

    PubMed

    Owen, Benjamin C; Jarrell, Tiffany M; Schwartz, Jae C; Oglesbee, Rob; Carlsen, Mark; Archibold, Enada F; Kenttämaa, Hilkka I

    2013-12-01

    A novel differentially pumped dual linear quadrupole ion trap (DLQIT) mass spectrometer was designed and built to facilitate tandem MS experiments free from interfering reactions. The instrument consists of two differentially pumped Thermo Scientific linear quadrupole ion trap (LQIT) systems that have been connected via an ion transfer octupole encased in a machined manifold. Tandem MS experiments can be performed in the front trap and then the resulting product ions can be transferred via axial ejection into the back trap for further, independent tandem MS experiments in a differentially pumped area. This approach allows the examination of consecutive collision-activated dissociation (CAD) and ion-molecule reactions without unwanted side reactions that often occur when CAD and ion-molecule reactions are examined in the same space. Hence, it greatly facilitates investigations of ion structures. In addition, the overall lower pressure of the DLQIT, as compared to commercial LQIT instruments, results in a reduction of unwanted side reactions with atmospheric contaminants, such as water and oxygen, in CAD and ion-molecule experiments. PMID:24171553

  10. Fabrication of broadband antireflective black metal surfaces with ultra-light-trapping structures by picosecond laser texturing and chemical fluorination

    NASA Astrophysics Data System (ADS)

    Zheng, Buxiang; Wang, Wenjun; Jiang, Gedong; Mei, Xuesong

    2016-06-01

    A hybrid method consisting of ultrafast laser-assisted texturing and chemical fluorination treatment was applied for efficiently enhancing the surface broadband antireflection to fabricate black titanium alloy surface with ultra-light-trapping micro-nanostructure. Based on the theoretical analysis of surface antireflective principle of micro-nanostructures and fluoride film, the ultra-light-trapping micro-nanostructures have been processed using a picosecond pulsed ultrafast laser on titanium alloy surfaces. Then fluorination treatment has been performed by using fluoroalkyl silane solution. According to X-ray diffraction phase analysis of the surface compositions and measurement of the surface reflectance using spectrophotometer, the broadband antireflective properties of titanium alloy surface with micro-nano structural characteristics were investigated before and after fluorination treatment. The results show that the surface morphology of micro-nanostructures processed by picosecond laser has significant effects on the antireflection of light waves to reduce the surface reflectance, which can be further reduced using chemical fluorination treatment. The high antireflection of over 98 % in a broad spectral range from ultraviolet to infrared on the surface of metal material has been achieved for the surface structures, and the broadband antireflective black metal surfaces with an extremely low reflectance of ultra-light-trapping structures have been obtained in the wavelength range from ultraviolet-visible to near-infrared, middle-wave infrared. The average reflectance of microgroove groups structured surface reaches as low as 2.43 % over a broad wavelength range from 200 to 2600 nm. It indicates that the hybrid method comprising of picosecond laser texturing and chemical fluorination can effectively induce the broadband antireflective black metal surface. This method has a potential application for fabricating antireflective surface used to improve the

  11. Mathieu Function Solutions for the Photoacoustic Effect in Two- and Three-Dimensional Structures and Optical Traps

    NASA Astrophysics Data System (ADS)

    Wu, Binbin; Diebold, Gerald J.

    2012-11-01

    The wave equation for the photoacoustic effect in a three-dimensional spherically symmetric, or two-dimensional structure where the compressibility or density varies sinusoidally in space reduces to an inhomogeneous Mathieu equation. As such, exact solutions for the photoacoustic pressure can be found in terms of either Mathieu functions, integer order Mathieu functions, or fractional order Mathieu functions, the last of these being of importance for problems pertaining to structures of finite dimensions. Here, frequency domain solutions are given for a spherical structure with material properties varying radially, and a two-dimensional structure with material variations in one direction. Solutions for the acoustic pressure are found that give closed form expressions for the resonance frequencies. It is also shown that Mathieu functions give solutions for the motion of an optically levitated sphere trapped in an intensity modulated, Gaussian laser beam. By determining the frequencies at which the motions of the sphere are largest, that is, where the Mathieu functions become unstable, it is shown that the trap can act to determine the radiation force relative to the gravitational force on the sphere.

  12. The impact of pore structure and surface roughness on capillary trapping for 2-D and 3-D porous media: Comparison with percolation theory

    NASA Astrophysics Data System (ADS)

    Geistlinger, Helmut; Ataei-Dadavi, Iman; Mohammadian, Sadjad; Vogel, Hans-Jörg

    2015-11-01

    We study the impact of pore structure and surface roughness on capillary trapping of nonwetting gas phase during imbibition with water for capillary numbers between 10-7 and 5 × 10-5, within glass beads, natural sands, glass beads monolayers, and 2-D micromodels. The materials exhibit different roughness of the pore-solid interface. We found that glass beads and natural sands, which exhibit nearly the same grain size distribution, pore size distribution, and connectivity, showed a significant difference of the trapped gas phase of about 15%. This difference can be explained by the microstructure of the pore-solid interface. Based on the visualization of the trapping dynamics within glass beads monolayers and 2-D micromodels, we could show that bypass trapping controls the trapping process in glass beads monolayers, while snap-off trapping controls the trapping process in 2-D micromodels. We conclude that these different trapping processes are the reason for the different trapping efficiency, when comparing glass beads packs with natural sand packs. Moreover, for small capillary numbers of 10-6, we found that the cluster size distribution of trapped gas clusters of all 2-D and 3-D porous media can be described by a universal power law behavior predicted from percolation theory. This cannot be expected a priori for 2-D porous media, because bicontinuity of the two bulk phases is violated. Obviously, bicontinuity holds for the thin-film water phase and the bulk gas phase. The snap-off trapping process leads to ordinary bond percolation in front of the advancing bulk water phase and is the reason for the observed universal power law behavior in 2-D micromodels with rough surfaces.

  13. Trapped antihydrogen.

    PubMed

    Andresen, G B; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Deller, A; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Hydomako, R; Jenkins, M J; Jonsell, S; Jørgensen, L V; Kurchaninov, L; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; el Nasr, S Seif; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2010-12-01

    Antimatter was first predicted in 1931, by Dirac. Work with high-energy antiparticles is now commonplace, and anti-electrons are used regularly in the medical technique of positron emission tomography scanning. Antihydrogen, the bound state of an antiproton and a positron, has been produced at low energies at CERN (the European Organization for Nuclear Research) since 2002. Antihydrogen is of interest for use in a precision test of nature's fundamental symmetries. The charge conjugation/parity/time reversal (CPT) theorem, a crucial part of the foundation of the standard model of elementary particles and interactions, demands that hydrogen and antihydrogen have the same spectrum. Given the current experimental precision of measurements on the hydrogen atom (about two parts in 10(14) for the frequency of the 1s-to-2s transition), subjecting antihydrogen to rigorous spectroscopic examination would constitute a compelling, model-independent test of CPT. Antihydrogen could also be used to study the gravitational behaviour of antimatter. However, so far experiments have produced antihydrogen that is not confined, precluding detailed study of its structure. Here we demonstrate trapping of antihydrogen atoms. From the interaction of about 10(7) antiprotons and 7 × 10(8) positrons, we observed 38 annihilation events consistent with the controlled release of trapped antihydrogen from our magnetic trap; the measured background is 1.4 ± 1.4 events. This result opens the door to precision measurements on anti-atoms, which can soon be subjected to the same techniques as developed for hydrogen. PMID:21085118

  14. Trapped antihydrogen.

    PubMed

    Andresen, G B; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Deller, A; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Hydomako, R; Jenkins, M J; Jonsell, S; Jørgensen, L V; Kurchaninov, L; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; el Nasr, S Seif; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2010-12-01

    Antimatter was first predicted in 1931, by Dirac. Work with high-energy antiparticles is now commonplace, and anti-electrons are used regularly in the medical technique of positron emission tomography scanning. Antihydrogen, the bound state of an antiproton and a positron, has been produced at low energies at CERN (the European Organization for Nuclear Research) since 2002. Antihydrogen is of interest for use in a precision test of nature's fundamental symmetries. The charge conjugation/parity/time reversal (CPT) theorem, a crucial part of the foundation of the standard model of elementary particles and interactions, demands that hydrogen and antihydrogen have the same spectrum. Given the current experimental precision of measurements on the hydrogen atom (about two parts in 10(14) for the frequency of the 1s-to-2s transition), subjecting antihydrogen to rigorous spectroscopic examination would constitute a compelling, model-independent test of CPT. Antihydrogen could also be used to study the gravitational behaviour of antimatter. However, so far experiments have produced antihydrogen that is not confined, precluding detailed study of its structure. Here we demonstrate trapping of antihydrogen atoms. From the interaction of about 10(7) antiprotons and 7 × 10(8) positrons, we observed 38 annihilation events consistent with the controlled release of trapped antihydrogen from our magnetic trap; the measured background is 1.4 ± 1.4 events. This result opens the door to precision measurements on anti-atoms, which can soon be subjected to the same techniques as developed for hydrogen.

  15. Bragg spectroscopy of trapped one-dimensional strongly interacting bosons in optical lattices: Probing the cake structure

    NASA Astrophysics Data System (ADS)

    Pupillo, Guido; Rey, Ana Maria; Batrouni, Ghassan George

    2006-07-01

    We study Bragg spectroscopy of strongly interacting one-dimensional bosons loaded in an optical lattice plus an additional parabolic potential. We calculate the dynamic structure factor by using Monte Carlo simulations for the Bose-Hubbard Hamiltonian, exact diagonalizations and the results of a recently introduced extended fermionization model. We find that, due to the system’s inhomogeneity, the excitation spectrum exhibits a multibranched structure, whose origin is related to the presence of superfluid regions with different densities in the atomic distribution. We thus suggest that Bragg spectroscopy in the linear regime can be used as an experimental tool to unveil the shell structure of alternating Mott insulator and superfluid phases characteristic of trapped bosons.

  16. Bragg spectroscopy of trapped one-dimensional strongly interacting bosons in optical lattices: Probing the cake structure

    SciTech Connect

    Pupillo, Guido; Rey, Ana Maria; Batrouni, Ghassan George

    2006-07-15

    We study Bragg spectroscopy of strongly interacting one-dimensional bosons loaded in an optical lattice plus an additional parabolic potential. We calculate the dynamic structure factor by using Monte Carlo simulations for the Bose-Hubbard Hamiltonian, exact diagonalizations and the results of a recently introduced extended fermionization model. We find that, due to the system's inhomogeneity, the excitation spectrum exhibits a multibranched structure, whose origin is related to the presence of superfluid regions with different densities in the atomic distribution. We thus suggest that Bragg spectroscopy in the linear regime can be used as an experimental tool to unveil the shell structure of alternating Mott insulator and superfluid phases characteristic of trapped bosons.

  17. Timescales of Kozai-Lidov oscillations at quadrupole and octupole order in the test particle limit

    NASA Astrophysics Data System (ADS)

    Antognini, J. M. O.

    2015-10-01

    Kozai-Lidov (KL) oscillations in hierarchical triple systems have found application to many astrophysical contexts, including planet formation, Type Ia supernovae, and supermassive black hole dynamics. The period of these oscillations is known at the order-of-magnitude level, but dependences on the initial mutual inclination or inner eccentricity are not typically included. In this work I calculate the period of KL oscillations (tKL) exactly in the test particle limit at quadrupole order (TPQ). I explore the parameter space of all hierarchical triples at TPQ and show that except for triples on the boundary between libration and rotation, the period of KL oscillations does not vary by more than a factor of a few. The exact period may be approximated to better than 2 per cent for triples with mutual inclinations between 60° and 120° and initial eccentricities less than ˜0.3. In addition, I derive an analytic expression for the period of octupole-order oscillations due to the `eccentric KL mechanism' (EKM). I show that the time-scale for EKM oscillations is proportional to ɛ _{oct}^{-1/2}, where ɛoct measures the strength of octupole perturbations relative to quadrupole perturbations.

  18. Non-Axial Octupole Deformations and Tetrahedral Symmetry in Heavy Nuclei

    SciTech Connect

    Mazurek, Katarzyna; Dudek, Jerzy

    2005-11-21

    The total energies of about 120 nuclei in the Thorium region have been calculated within the macroscopic-microscopic method in the 5-dimensional space of deformation parameters {alpha}20, {alpha}22, {alpha}30, {alpha}32 and {alpha}40. The macroscopic energy term contains the nuclear surface-curvature dependence as proposed within the LSD approach. The microscopic energies are calculated with the Woods-Saxon single particle potential employing the universal set of parameters.We study a possible presence of the octupole axial and non-axial degrees of freedom all-over in the ({beta}, {gamma})-plane focussing on the ground-states, secondary minima and in the saddle points. In fact, a competition between axial and tri-axial octupole deformation parameters is obtained at the saddle points and in the secondary minima for many isotones with N > 136. The presence of the tetrahedral symmetry minima is predicted in numerous nuclei in the discussed region, although most of the time at relatively high excitation energies.

  19. Universal nonmonotonic structure in the saturation curves of magneto-optical-trap-loaded Na+ ions stored in an ion-neutral hybrid trap: Prediction and observation

    NASA Astrophysics Data System (ADS)

    Blümel, R.; Wells, J. E.; Goodman, D. S.; Kwolek, J. M.; Smith, W. W.

    2015-12-01

    We predict that the maximal, steady-state ion capacity Ns(λ ) of radio-frequency (rf) traps, loaded at a rate of λ particles per rf cycle, shows universal, nonlinear, nonmonotonic behavior as a function of loading rate λ . The shape of Ns(λ ) , characterized by four dynamical regimes, is universal; i.e., it is predicted to manifest itself in all types of rf traps independent of the details of their construction and independent of particle species loaded. For λ ≪ 1 (region I), as expected, Ns(λ ) increases monotonically with λ . However, contrary to intuition, at intermediate λ ˜1 (region II), Ns(λ ) reaches a maximum, followed by a local minimum of Ns(λ ) (region III). For λ ≫1 (region IV), Ns(λ ) again rises monotonically. In region IV, numerical simulations, analytical calculations, and experiments show Ns(λ ) ˜λ2 /3 . We confirm our predictions both experimentally with magneto-optical-trap-loaded Na+ ions stored in a hybrid ion-neutral trap and numerically with the help of detailed ab initio molecular-dynamics simulations.

  20. Structural asymmetry in the closed state of mitochondrial Hsp90 (TRAP1) supports a two-step ATP hydrolysis mechanism

    PubMed Central

    Lavery, Laura A.; Partridge, James R.; Ramelot, Theresa A.; Elnatan, Daniel; Kennedy, Michael A.; Agard, David A.

    2014-01-01

    Summary While structural symmetry is a prevailing feature of homo-oligomeric proteins, asymmetry provides unique mechanistic opportunities. We present the crystal structure of full-length TRAP1, the mitochondrial Hsp90 molecular chaperone, in a catalytically active closed state. The TRAP1 homodimer adopts a distinct, asymmetric conformation, where one protomer is reconfigured via a helix swap at the Middle:C-terminal Domain (MD:CTD) interface. Importantly, this interface plays a critical role in client binding. Solution methods validate the asymmetry and show extension to Hsp90 homologs. Point mutations that disrupt unique contacts at each MD:CTD interface reduce catalytic activity, substrate binding, and demonstrate that each protomer needs access to both conformations. Crystallographic data on a dimeric NTD:MD fragment suggests that asymmetry arises from strain induced by simultaneous NTD and CTD dimerization. The observed asymmetry provides the potential for an additional step in the ATPase cycle, allowing sequential ATP hydrolysis steps to drive both client remodeling and client release. PMID:24462206

  1. Spill-point analysis and structural trapping capacity in saline aquifers using MRST-co2lab

    NASA Astrophysics Data System (ADS)

    Møll Nilsen, Halvor; Lie, Knut-Andreas; Møyner, Olav; Andersen, Odd

    2015-02-01

    Geological carbon storage represents a substantial challenge for the subsurface geosciences. Knowledge of the subsurface can be captured in a quantitative form using computational methods developed within petroleum production. However, to provide good estimates of the likely outcomes over thousands of years, traditional 3D simulation methods should be combined with other techniques developed specifically to study large-scale, long-term migration problems, e.g., in basin modeling. A number of such methods have been developed as a separate module in the open-source Matlab Reservoir Simulation Toolbox (MRST). In this paper, we present a set of tools provided by this module, consisting of geometrical and percolation type methods for computing structural traps and spill paths below a sealing caprock. Using concepts from water management, these tools can be applied on large-scale aquifer models to quickly estimate potential for structural trapping, determine spill paths from potential injection points, suggest optimal injection locations, etc. We demonstrate this by a series of examples applied on publicly available datasets. The corresponding source code is provided along with the examples.

  2. Volume calculation of subsurface structures and traps in hydrocarbon exploration — a comparison between numerical integration and cell based models

    NASA Astrophysics Data System (ADS)

    Slavinić, Petra; Cvetković, Marko

    2016-01-01

    The volume calculation of geological structures is one of the primary goals of interest when dealing with exploration or production of oil and gas in general. Most of those calculations are done using advanced software packages but still the mathematical workflow (equations) has to be used and understood for the initial volume calculation process. In this paper a comparison is given between bulk volume calculations of geological structures using trapezoidal and Simpson's rule and the ones obtained from cell-based models. Comparison in calculation is illustrated with four models; dome - 1/2 of ball/sphere, elongated anticline, stratigraphic trap due to lateral facies change and faulted anticline trap. Results show that Simpson's and trapezoidal rules give a very accurate volume calculation even with a few inputs(isopach areas - ordinates). A test of cell based model volume calculation precision against grid resolution is presented for various cases. For high accuracy, less the 1% of an error from coarsening, a cell area has to be 0.0008% of the reservoir area

  3. Simulations of plasma confinement in an antihydrogen trap

    SciTech Connect

    Gomberoff, K.; Fajans, J.; Friedman, A.; Grote, D.; Vay, J.-L.; Wurtele, J.S.

    2007-10-15

    The three-dimensional particle-in-cell (3-D PIC) simulation code WARP is used to study positron confinement in antihydrogen traps. The magnetic geometry is close to that of a UC Berkeley experiment conducted, with electrons, as part of the ALPHA collaboration (W. Bertsche et al., AIP Conf. Proc. 796, 301 (2005)). In order to trap antihydrogen atoms, multipole magnetic fields are added to a conventional Malmberg-Penning trap. These multipole fields must be strong enough to confine the antihydrogen, leading to multipole field strengths at the trap wall comparable to those of the axial magnetic field. Numerical simulations reported here confirm recent experimental measurements of reduced particle confinement when a quadrupole field is added to a Malmberg-Penning trap. It is shown that, for parameters relevant to various antihydrogen experiments, the use of an octupole field significantly reducesthe positron losses seen with a quadrupole field. A unique method for obtaining a 3-D equilibrium of the positrons in the trap with a collisionless PIC code was developed especially for the study of the antihydrogen trap; however, it is of practical use for other traps as well.

  4. Simulations of plasma confinement in an antihydrogen trap

    SciTech Connect

    Gomberoff, K.; Fajans, J.; Friedman, A.; Grote, D.; Vay, J.-L.; Wurtele, J. S.

    2007-10-15

    The three-dimensional particle-in-cell (3-D PIC) simulation code WARP is used to study positron confinement in antihydrogen traps. The magnetic geometry is close to that of a UC Berkeley experiment conducted, with electrons, as part of the ALPHA collaboration [W. Bertsche et al., AIP Conf. Proc. 796, 301 (2005)]. In order to trap antihydrogen atoms, multipole magnetic fields are added to a conventional Malmberg-Penning trap. These multipole fields must be strong enough to confine the antihydrogen, leading to multipole field strengths at the trap wall comparable to those of the axial magnetic field. Numerical simulations reported here confirm recent experimental measurements of reduced particle confinement when a quadrupole field is added to a Malmberg-Penning trap. It is shown that, for parameters relevant to various antihydrogen experiments, the use of an octupole field significantly reduces the positron losses seen with a quadrupole field. A unique method for obtaining a 3-D equilibrium of the positrons in the trap with a collisionless PIC code was developed especially for the study of the antihydrogen trap; however, it is of practical use for other traps as well.

  5. Concentric Magnetic Structures for Magnetophoretic Bead Collection, Cell Trapping and Analysis of Cell Morphological Changes Caused by Local Magnetic Forces

    PubMed Central

    Huang, Chen-Yu; Wei, Zung-Hang

    2015-01-01

    Concentric magnetic structures (ring and square) with domain wall (DW) pinning geometry are designed for biological manipulation. Magnetic beads collection was firstly demonstrated to analyse the local magnetic field generated by DWs and the effective regions to capture magnetic targets of size 1 μm. Primary mouse embryonic fibroblasts (MEFs) are magnetically labeled by internalizing poly (styrene sulfonic acid) stabilized magnetic nanoparticles (PSS-MNPs) and then are selectively trapped by head-to-tail DWs (HH DWs) or tail-to-tail DWs (TT DWs) to be arranged into linear shape or cross shape. The morphologies and the nuclear geometry of the cells growing on two kinds of concentric magnetic structures are shown to be distinctive. The intracellular magnetic forces generated by the local magnetic field of DWs are found to influence the behaviour of cells. PMID:26270332

  6. One-phonon octupole vibrational states in 211At, 212Rn, 213Fr and 214Ra with N = 126

    NASA Astrophysics Data System (ADS)

    Hwang, J. K.; Hamilton, J. H.; Ramayya, A. V.

    2013-12-01

    Excited high spin states in 211At, 212Rn, 213Fr and 214Ra with N = 126 are reorganized and interpreted in terms of the stretched weak coupling of an octupole 3- phonon. Nearly identical sequences of levels with ΔI = 3 and the parity change are found, for the first time, up to 25- for 20 states of 214Ra, up to 35- for 36 states of 212Rn and up to 53/2+ for 16 states of 213Fr. The stretched weak coupling of an octupole phonon is extended up to the highest excitation energy of 11355 keV for 212Rn which has the largest experimental B( E3) value of 44.1(88) W.u. for the 11- → 8{2/+} transition. The stretched weak coupling of an octupole 3- phonon needs to be considered when single particle configurations are assigned to high spin states. Average octupole excitation energies of 657(51) keV for 211At, 1101(28) keV for 212Rn, 667(25) keV for 213Fr, and 709(25) keV for 214Ra are obtained. The calculated level enegies are in a good agreement with the experimental level energies within the error limit of 4.3%.

  7. Effective Light Trapping in Thin Film Silicon Solar Cells with Nano- and Microscale Structures on Glass Substrate.

    PubMed

    Bong, Sungjae; Ahn, Shihyun; Anh, Le Huy Tuan; Kim, Sunbo; Park, Hyeongsik; Shin, Chonghoon; Park, Jinjoo; Lee, Younjung; Yi, Junsin

    2016-05-01

    For thin film silicon-based solar cells, effective light trapping at a broad range of wavelengths (400-1100 nm) is necessary. Normally, etching is only carried out with TCOs, such as SnO2:F and impurity doped ZnO, to form nano-sized craters in the surface morphology to confer a light trapping effect. However, in this study, prior to ZnO:Al etching, periodic structures on the glass substrates were made by photolithography and wet etching to increase the light scattering and internal reflection. The use of periodic structures on the glass substrate resulted in higher haze ratios in the range from 550 nm to 1100 nm, which is the optical absorption wavelength region for thin film silicon solar cells, than obtained by simple ZnO:Al etching. The periodically textured glass with micro-sized structures compensates for the low haze ratio at the middle and long wavelengths of wet etched ZnO:Al. ZnO:Al was deposited on the periodically textured glass, after which the ZnO:Al surface was also etched randomly using a mixed acid solution to form nano-sized craters. The thin film silicon solar cells with 350-nm-thick amorphous silicon absorber layer deposited on the periodic structured glass and etched ZnO:Al generated up to 10.68% more photocurrent, with 11.2% increase of the conversion efficiency compared to the cell deposited on flat glass and etched ZnO:Al. PMID:27483855

  8. Octupole excitations in 141,144Cs and the pronounced decrease of dipole moments with neutron number in odd- Z neutron-rich 141,143,144Cs

    NASA Astrophysics Data System (ADS)

    Luo, Y. X.; Rasmussen, J. O.; Hamilton, J. H.; Ramayya, A. V.; Liu, S. H.; Jones, E. F.; Gore, P. M.; Goodin, C.; Stone, N. J.; Zhu, S. J.; Hwang, J. K.; Li, Ke; Crowell, H. L.; Lee, I. Y.; Ter-Akopian, G. M.; Daniel, A. V.; Stoyer, M. A.; Donangelo, R.; Ma, W. C.; Cole, J. D.

    2010-07-01

    The level scheme of odd- Z neutron-rich 141Cs ( Z=55, N=86) was extended and expanded and that of 144Cs ( N=89) was identified for the first time by means of γ-γ-γ coincidence measurements of prompt γ rays in the spontaneous fission of 252Cf with Gammasphere. Spin/parity was assigned to the levels based on angular correlations and level systematics in 141,143Cs. Parity doublets characteristic of both simplex quantum number s=+i and s=-i were proposed in 141Cs. The tests by using rotational frequency ratio ω(I)/ω(I) imply octupole vibrations in 141Cs and 143Cs. B(E1)/B(E2) values and electric dipole moments D were calculated for 141Cs, and re-determined for 143Cs. It was found that B(E1)/B(E2) values of 141Cs are simplex-dependent and the average value is one order of magnitude larger than that of 143Cs, and the deduced dipole moment D of 141Cs is considerably larger than that of 143Cs, and comparable to the N=86 isotone 142Ba. For 144Cs the yrast sequence looks like a well-deformed rotational band, but no octupole band structure was identified in this nucleus. The overall variations of D in 141,143,144Cs exhibit a pronounced drop of dipole moment with increasing neutron number in this odd- Z isotopic chain, which may be analogous in nature to the quenching of D observed in even-even 146Ba ( Z=56, N=90) and 224Ra ( Z=88, N=136), and to the drop of D in the odd- Z neutron-rich 147La ( Z=57, N=90) reported by our collaboration.

  9. Finite vortex numbers and symmetric vortex structures in a rotating trapped Fermi gas in the BCS-BEC crossover

    NASA Astrophysics Data System (ADS)

    Song, T. L.; Ma, Y. L.

    2011-08-01

    The ground state of a three-dimensional (3D) rotating trapped superfluid Fermi gas in the BCS-BEC crossover is mapped to finite N v -body vortex states by a simple ansatz. The total vortex energy is measured from the ground-state energy of the system in the absence of the vortices. The vortex state is stable since the vortex potential and rotation energies are attractive while the vortex kinetic energy and interaction between vortices are repulsive. By combining the analytical and numerical works for the minimal vortex energy, the 2D configurations of N v vortices are studied by taking into account of the finite size effects both on xy-plane and on z-direction. The calculated vortex numbers as a function of the interaction strength are appropriate to the renew experimental results by Zwierlein in [ High-temperature superfluidity in a ultracold Fermi gas, Ph.D. thesis, Massachusetts Institute of Technology, 2006]. The numerical results show that there exist two types of vortex structures: the trap center is occupied and unoccupied by a vortex, even in the case of N v < 10 with regular polygon and in the case of N v ≥ 10 with finite triangle lattice. The rotation frequency dependent vortex numbers with different interaction strengths are also discussed.

  10. Quantitative analysis of seismic fault zone waves in the rupture zone of the 1992 Landers, California, earthquake: Evidence for a shallow trapping structure

    USGS Publications Warehouse

    Peng, Z.; Ben-Zion, Y.; Michael, A.J.; Zhu, L.

    2003-01-01

    We analyse quantitatively a waveform data set of 238 earthquakes recorded by a dense seismic array across and along the rupture zone of the 1992 Landers earthquake. A grid-search method with station delay corrections is used to locate events that do not have catalogue locations. The quality of fault zone trapped waves generated by each event is determined from the ratios of seismic energy in time windows corresponding to trapped waves and direct S waves at stations close to and off the fault zone. Approximately 70 per cent of the events with S-P times of less than 2 s, including many clearly off the fault, produce considerable trapped wave energy. This distribution is in marked contrast with previous claims that trapped waves are generated only by sources close to or inside the Landers rupture zone. The time difference between the S arrival and trapped waves group does not grow systematically with increasing hypocentral distance and depth. The dispersion measured from the trapped waves is weak. These results imply that the seismic trapping structure at the Landers rupture zone is shallow and does not extend continuously along-strike by more than a few kilometres. Synthetic waveform modelling indicates that the fault zone waveguide has depth of approximately 2-4 km, a width of approximately 200 m, an S-wave velocity reduction relative to the host rock of approximately 30-40 per cent and an S-wave attenuation coefficient of approximately 20-30. The fault zone waveguide north of the array appears to be shallower and weaker than that south of the array. The waveform modelling also indicates that the seismic trapping structure below the array is centred approximately 100 m east of the surface break.

  11. Evidence for octupole correlation and chiral symmetry breaking in 124Cs

    NASA Astrophysics Data System (ADS)

    Selvakumar, K.; Singh, A. K.; Ghosh, Chandan; Singh, Purnima; Goswami, A.; Raut, R.; Mukherjee, A.; Datta, U.; Datta, P.; Roy, S.; Gangopadhyay, G.; Bhowal, S.; Muralithar, S.; Kumar, R.; Singh, R. P.; Raju, M. Kumar

    2015-12-01

    Lifetime measurements have been carried out using the Doppler shift attenuation method (DSAM) for the negative- and positive-parity bands built on π h11/2⊗ν (d5/2g7/2) and π h11/2⊗ν h11/2 configurations, respectively, in 124Cs. The reduced transition probabilities have been obtained for both the bands and are compared with the available theoretical calculations. The enhanced B (E 1 ) rates for the linking transitions between the bands with the above configurations suggest the existence of octupole correlations in 124Cs. The observed electromagnetic properties for the positive-parity bands in 124Cs agree well with the characteristics pattern required for chiral symmetry breaking.

  12. Octupole Magnet For Soft X Ray Magnetic Dichroism Experiments: Design and Performance

    SciTech Connect

    Arenholz, Elke; Prestemon, Soren O.

    2004-05-12

    An octupole magnet endstation for soft x ray magnetic dichroism measurements has been developed at the Advanced Light Source. The system consists of an eight pole electromagnet that surrounds a small vacuum chamber. The magnet provides fields up to 0.9 T that can be applied in any direction relative to the incoming x ray beam. High precision magnetic circular and linear dichroism spectra can be obtained reversing the magnetic field for each photon energy in an energy scan. Moreover, the field dependence of all components of the magnetization vector can be studied in detail by choosing various angles of x ray incidence while keeping the relative orientation of magnetic field and sample fixed.

  13. COLD TRAPS

    DOEpatents

    Thompson, W.I.

    1958-09-30

    A cold trap is presented for removing a condensable component from a gas mixture by cooling. It consists of a shell, the exterior surface of which is chilled by a refrigerant, and conductive fins welded inside the shell to condense the gas, and distribute the condensate evenly throughout the length of the trap, so that the trap may function until it becomes completely filled with the condensed solid. The contents may then be removed as either a gas or as a liquid by heating the trap. This device has particuinr use as a means for removing uranium hexafluoride from the gaseous diffusion separation process during equipment breakdown and repair periods.

  14. Optical trapping

    PubMed Central

    Neuman, Keir C.; Block, Steven M.

    2006-01-01

    Since their invention just over 20 years ago, optical traps have emerged as a powerful tool with broad-reaching applications in biology and physics. Capabilities have evolved from simple manipulation to the application of calibrated forces on—and the measurement of nanometer-level displacements of—optically trapped objects. We review progress in the development of optical trapping apparatus, including instrument design considerations, position detection schemes and calibration techniques, with an emphasis on recent advances. We conclude with a brief summary of innovative optical trapping configurations and applications. PMID:16878180

  15. Atomic structure of Hsp90-Cdc37-Cdk4 reveals that Hsp90 traps and stabilizes an unfolded kinase.

    PubMed

    Verba, Kliment A; Wang, Ray Yu-Ruei; Arakawa, Akihiko; Liu, Yanxin; Shirouzu, Mikako; Yokoyama, Shigeyuki; Agard, David A

    2016-06-24

    The Hsp90 molecular chaperone and its Cdc37 cochaperone help stabilize and activate more than half of the human kinome. However, both the mechanism by which these chaperones assist their "client" kinases and the reason why some kinases are addicted to Hsp90 while closely related family members are independent are unknown. Our structural understanding of these interactions is lacking, as no full-length structures of human Hsp90, Cdc37, or either of these proteins with a kinase have been elucidated. Here we report a 3.9 angstrom cryo-electron microscopy structure of the Hsp90-Cdc37-Cdk4 kinase complex. Surprisingly, the two lobes of Cdk4 are completely separated with the β4-β5 sheet unfolded. Cdc37 mimics part of the kinase N lobe, stabilizing an open kinase conformation by wedging itself between the two lobes. Finally, Hsp90 clamps around the unfolded kinase β5 strand and interacts with exposed N- and C-lobe interfaces, protecting the kinase in a trapped unfolded state. On the basis of this structure and an extensive amount of previously collected data, we propose unifying conceptual and mechanistic models of chaperone-kinase interactions. PMID:27339980

  16. Atomic structure of Hsp90-Cdc37-Cdk4 reveals that Hsp90 traps and stabilizes an unfolded kinase.

    PubMed

    Verba, Kliment A; Wang, Ray Yu-Ruei; Arakawa, Akihiko; Liu, Yanxin; Shirouzu, Mikako; Yokoyama, Shigeyuki; Agard, David A

    2016-06-24

    The Hsp90 molecular chaperone and its Cdc37 cochaperone help stabilize and activate more than half of the human kinome. However, both the mechanism by which these chaperones assist their "client" kinases and the reason why some kinases are addicted to Hsp90 while closely related family members are independent are unknown. Our structural understanding of these interactions is lacking, as no full-length structures of human Hsp90, Cdc37, or either of these proteins with a kinase have been elucidated. Here we report a 3.9 angstrom cryo-electron microscopy structure of the Hsp90-Cdc37-Cdk4 kinase complex. Surprisingly, the two lobes of Cdk4 are completely separated with the β4-β5 sheet unfolded. Cdc37 mimics part of the kinase N lobe, stabilizing an open kinase conformation by wedging itself between the two lobes. Finally, Hsp90 clamps around the unfolded kinase β5 strand and interacts with exposed N- and C-lobe interfaces, protecting the kinase in a trapped unfolded state. On the basis of this structure and an extensive amount of previously collected data, we propose unifying conceptual and mechanistic models of chaperone-kinase interactions.

  17. Optical Trapping of Nanoparticles

    PubMed Central

    Bergeron, Jarrah; Zehtabi-Oskuie, Ana; Ghaffari, Saeedeh; Pang, Yuanjie; Gordon, Reuven

    2013-01-01

    Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping and manipulating small biological particles. Ashkin and co-workers first demonstrated optical tweezers using a single focused beam1. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles1. In the perturbative regime, the optical power required for trapping a particle scales as the inverse fourth power of the particle size. High optical powers can damage dielectric particles and cause heating. For instance, trapped latex spheres of 109 nm in diameter were destroyed by a 15 mW beam in 25 sec1, which has serious implications for biological matter2,3. A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime4. In a non-perturbative regime, even a small particle with little permittivity contrast to the background can influence significantly the ambient electromagnetic field and induce a large optical force. As a particle enters an illuminated aperture, light transmission increases dramatically because of dielectric loading. If the particle attempts to leave the aperture, decreased transmission causes a change in momentum outwards from the hole and, by Newton's Third Law, results in a force on the particle inwards into the hole, trapping the particle. The light transmission can be monitored; hence, the trap can become a sensor. The SIBA trapping technique can be further improved by using a double-nanohole structure. The double-nanohole structure has been shown to give a strong local field enhancement5,6. Between the two sharp tips of the double-nanohole, a small particle can cause a large change in optical transmission, thereby inducing a large optical force. As a result, smaller nanoparticles can be trapped, such as 12 nm silicate spheres7 and 3.4 nm

  18. A shallow fault-zone structure illuminated by trapped waves in the Karadere-Duzce branch of the North Anatolian Fault, western Turkey

    USGS Publications Warehouse

    Ben-Zion, Y.; Peng, Z.; Okaya, D.; Seeber, L.; Armbruster, J.G.; Ozer, N.; Michael, A.J.; Baris, S.; Aktar, M.

    2003-01-01

    We discuss the subsurface structure of the Karadere-Duzce branch of the North Anatolian Fault based on analysis of a large seismic data set recorded by a local PASSCAL network in the 6 months following the Mw = 7.4 1999 Izmit earthquake. Seismograms observed at stations located in the immediate vicinity of the rupture zone show motion amplification and long-period oscillations in both P- and S-wave trains that do not exist in nearby off-fault stations. Examination of thousands of waveforms reveals that these characteristics are commonly generated by events that are well outside the fault zone. The anomalous features in fault-zone seismograms produced by events not necessarily in the fault may be referred to generally as fault-zone-related site effects. The oscillatory shear wave trains after the direct S arrival in these seismograms are analysed as trapped waves propagating in a low-velocity fault-zone layer. The time difference between the S arrival and trapped waves group does not grow systematically with increasing source-receiver separation along the fault. These observations imply that the trapping of seismic energy in the Karadere-Duzce rupture zone is generated by a shallow fault-zone layer. Traveltime analysis and synthetic waveform modelling indicate that the depth of the trapping structure is approximately 3-4 km. The synthetic waveform modelling indicates further that the shallow trapping structure has effective waveguide properties consisting of thickness of the order of 100 m, a velocity decrease relative to the surrounding rock of approximately 50 per cent and an S-wave quality factor of 10-15. The results are supported by large 2-D and 3-D parameter space studies and are compatible with recent analyses of trapped waves in a number of other faults and rupture zones. The inferred shallow trapping structure is likely to be a common structural element of fault zones and may correspond to the top part of a flower-type structure. The motion amplification

  19. Protein crystallography for aspiring crystallographers or how to avoid pitfalls and traps in macromolecular structure determination

    PubMed Central

    Wlodawer, Alexander; Minor, Wladek; Dauter, Zbigniew; Jaskolski, Mariusz

    2014-01-01

    The number of macromolecular structures deposited in the Protein Data Bank now approaches 100 000, with the vast majority of them determined by crystallographic methods. Thousands of papers describing such structures have been published in the scientific literature, and 20 Nobel Prizes in chemistry or medicine have been awarded for discoveries based on macromolecular crystallography. New hardware and software tools have made crystallography appear to be an almost routine (but still far from being analytical) technique and many structures are now being determined by scientists with very limited experience in the practical aspects of the field. However, this apparent ease is sometimes illusory and proper procedures need to be followed to maintain high standards of structure quality. In addition, many noncrystallographers may have problems with the critical evaluation and interpretation of structural results published in the scientific literature. The present review provides an outline of the technical aspects of crystallography for less experienced practitioners, as well as information that might be useful for users of macromolecular structures, aiming to show them how to interpret (but not overinterpret) the information present in the coordinate files and in their description. A discussion of the extent of information that can be gleaned from the atomic coordinates of structures solved at different resolution is provided, as well as problems and pitfalls encountered in structure determination and interpretation. PMID:24034303

  20. Protein crystallography for aspiring crystallographers or how to avoid pitfalls and traps in macromolecular structure determination.

    PubMed

    Wlodawer, Alexander; Minor, Wladek; Dauter, Zbigniew; Jaskolski, Mariusz

    2013-11-01

    The number of macromolecular structures deposited in the Protein Data Bank now approaches 100,000, with the vast majority of them determined by crystallographic methods. Thousands of papers describing such structures have been published in the scientific literature, and 20 Nobel Prizes in chemistry or medicine have been awarded for discoveries based on macromolecular crystallography. New hardware and software tools have made crystallography appear to be an almost routine (but still far from being analytical) technique and many structures are now being determined by scientists with very limited experience in the practical aspects of the field. However, this apparent ease is sometimes illusory and proper procedures need to be followed to maintain high standards of structure quality. In addition, many noncrystallographers may have problems with the critical evaluation and interpretation of structural results published in the scientific literature. The present review provides an outline of the technical aspects of crystallography for less experienced practitioners, as well as information that might be useful for users of macromolecular structures, aiming to show them how to interpret (but not overinterpret) the information present in the coordinate files and in their description. A discussion of the extent of information that can be gleaned from the atomic coordinates of structures solved at different resolution is provided, as well as problems and pitfalls encountered in structure determination and interpretation.

  1. Modelling of the influence of charges trapped in the oxide on the I(Vg) characteristics of metal ultra-thin oxide semiconductor structures

    NASA Astrophysics Data System (ADS)

    Aziz, A.; Kassmi, K.; Kassmi, Ka; Olivie, F.

    2004-07-01

    This paper deals with the theoretical and experimental influences of the charge trapped in the oxide of metal/ultra-thin oxide/semiconductor structures. It focuses on the two characteristics current-voltage I(Vg) and voltage-charges injected Vg(Qinj) (Vg is the voltage applied, Qinj is the injected charge) when the conduction is of the Fowler-Nordheim type. The charge is trapped in the thin oxide after injection of a constant current at high field (>12 MV cm-1) from the metal (in accumulation regime: Vg < 0). This study considers that, after a given injection, the charge centroid is fixed during the acquisition of the I(Vg) characteristics. A method is proposed to determine the trapped charge characteristics (density and centroid) by analysing the theoretical and experimental I(Vg) and Vg(Qinj) characteristics. It is shown that the constant current injection creates a charge trapped in the oxide near the cathode. When the injected charge increases, the trapped charge density increases linearly and the charge centroid position shifts exponentially towards the injecting electrode. These results enable us to draw conclusions on the instability of the trapped charge. Indeed the increase in the charges injected causes the movement of the charge centroid towards the cathode.

  2. Lenticular stretch structures in eastern Nevada - possible trapping mechanism in supposed graben

    SciTech Connect

    Walker, C.T.; Dennis, J.G.; Lumsden, W.W.

    1986-04-01

    Eastern Nevada is widely recognized as a region of tectonic extension. The dominant structures are generally agreed to be low-dipping, younger over older faults and steeper listric faults that are responsible for the basins (grabens) and ranges (horsts). In the Schell Creek-Duck Creek Range, east of Ely, and in the White Pine Range, southwest of Ely, small lenticular structures bounded by tectonic discontinuities can be clearly seen in the field. These lenticular units, or stretch structures, range in length from a few meters to more than 200 m. All lenticular stretch structures that can be clearly seen in the field are stratigraphically restricted; the stretched formations are the Eureka Quartzite, the Pilot Shale, the Joana Limestone, and the Chainman Shale. Still larger stretch structures, which may include several formations, are inferred, and the authors suggest that extension has created lenticular structures at all scales. The Duck Creek and Schell Creek Ranges east of Ely consist mostly of Devonian and older rocks. They are separated by a topographically lower area containing mostly Mississippian and Pennsylvanian rocks. This structure, which separates the ranges, has been referred to as a graben, but field evidence suggests that it is a large-scale lenticular stretch structure. Unlike a true graben, the structure does not extend downward. For example, in several places within the supposed graben, Cambrian and Ordovician rocks project through a cover of Carboniferous Chainman Shale and Ely Limestone, suggesting the Chainman-Ely is a thin sheet underlain by Cambrian-Ordovician rocks. Accordingly, they suggest that extension in the Duck Creek-Schell Creek Ranges stretched the formations into lenticular bodies. Between the Duck Creek and Schell Creek Ranges, the Cambrian-Ordovician is attenuated, and the resulting tectonic depression is occupied by a lenticular mass of Carboniferous rocks.

  3. Nanoscale interfacial structure for Novel Opto-electronic and Ion-trapping Devices

    NASA Astrophysics Data System (ADS)

    Ulin-Avila, Erick

    In this dissertation, we present contributions to the nanoscale engineering of electronic and geometrical structure of dielectric-metal interfaces. Such structure is designed to support the interaction of light and matter for useful scientific and technological applications. Among our interests are electromagnetic subwavelength localization, propagation and storage; photonic manipulation, modulation, synchronization and its use in the confinement of atomic systems. The latter is directed towards a new generation of scalable devices for quantum information processing (QIP) and surface science studies.

  4. Oxygen trapped by rare earth tetrahedral clusters in Nd{sub 4}FeOS{sub 6}: Crystal structure, electronic structure, and magnetic properties

    SciTech Connect

    Lin, Qisheng; Taufour, Valentin; Zhang, Yuemei; Wood, Max; Drtina, Thomas; Bud’ko, Sergey L.; Canfield, Paul C.; Miller, Gordon J.

    2015-09-15

    Single crystals of Nd{sub 4}FeOS{sub 6} were grown from an Fe–S eutectic solution. Single crystal X-ray diffraction analysis revealed a Nd{sub 4}MnOSe{sub 6}-type structure (P6{sub 3}mc, a=9.2693(1) Å, c=6.6650(1)Å, V=495.94(1) Å{sup 3}, Z=2), featuring parallel chains of face-sharing [FeS{sub 6×1/2}]{sup 4−} trigonal antiprisms and interlinked [Nd{sub 4}OS{sub 3}]{sup 4+} cubane-like clusters. Oxygen atoms were found to be trapped by Nd{sub 4} clusters in the [Nd{sub 4}OS{sub 3}]{sup 4{sub +}} chains. Structural differences among Nd{sub 4}MnOSe{sub 6}-type Nd{sub 4}FeOS{sub 6} and the related La{sub 3}CuSiS{sub 7}− and Pr{sub 8}CoGa{sub 3}-type structures have been described. Magnetic susceptibility measurements on Nd{sub 4}FeOS{sub 6} suggested the dominance of antiferromagnetic interactions at low temperature, but no magnetic ordering down to 2 K was observed. Spin-polarized electronic structure calculations revealed magnetic frustration with dominant antiferromagnetic interactions. - Graphical abstract: Trapping of oxygen in Nd{sub 4} tetrahedral clusters results in the formation of the Nd{sub 4}MnOSe{sub 6}-type Nd{sub 4}FeOS{sub 6}, in contrast to the La{sub 3}CuSiS{sub 7}-type oxygen-free Nd{sub 4}FeS{sub 7} and related Pr{sub 8}CoGa{sub 3}-type structures. Complex magnetic frustration inhibits magnetic ordering at low temperature. - Highlights: • Single crystals of Nd{sub 4}FeOS{sub 6} were grown using self-flux method. • Oxygen was found trapped by Nd{sub 4} tetrahedral clusters. • Comparison with two closely related structural types were discussed. • Magnetic measurements revealed antiferromagnetic (AFM) interaction. • VASP calculations confirmed strong magnetic frustration in AFM model.

  5. Stratigraphic traps 2

    SciTech Connect

    Not Available

    1991-01-01

    This volume contains studies of fields with traps that are mainly stratigraphic in nature. Structure plays a role in the traps of several fields, but overall, it is clear that the main trapping features with the group of fields in this volume are stratigraphic. The first six fields in this volume, Alabama Ferry, Rospo Mare, Walker Creek, Bindley, Lexington, and Newburg/South Westhope, have carbonate reservoirs. The latter two of these, Lexington and Newburg/South Westhope, also have sandstone reservoirs. The remaining fields, East Texas, East Clinton, Stockholm Southwest, Sorrento, Port Acres, and Lagoa Parda, have only sandstone reservoirs.

  6. Structural style and hydrocarbon trap of Karbasi anticline, in the Interior Fars region, Zagros, Iran

    NASA Astrophysics Data System (ADS)

    Maleki, Z.; Arian, M.; Solgi, A.

    2014-07-01

    Karbasi anticline between west-northwest parts of Jahrom town is located in northwest 40 km distance of Aghar gas anticline in interior Fars region. This anticline has asymmetric structure and some faults with large strike separation observed in its structure. The operation of Nezamabad sinistral strike slip fault in west part of this anticline caused fault plunge change in this region. Because of complication increasing of structures geometry in Fars region and necessity to exploration activities for deeper horizons especially the Paleozoic ones, the analysis of fold style elements, which is known as one of the main parts in structural studies seems necessary. In this paper because of some reasons such as Karbasi anticline structural complication, importance of drilling and hydrocarbon explorations in Fars region, it is proceed to analysis and evaluation of fold style elements and geometry with emphasis on Nezamabad fault operation in Interior Fars region. According to fold style elements analysis results, it became clear that in east part of anticline the type of fold horizontal moderately inclined and in west part it is upright moderately plunging, so west evaluation of anticline is affected by more deformation. In this research the relationship present faults especially the Nezamabad sinistral strike slip one with folding and its affection on Dehram horizon and Bangestan group were modeled. Based on received results may be the Nezamabad fault is located between G-G' and E-E' structural sections and this fault in this area operated same as fault zone. In different parts of Karbasi anticline, Dashtak formation as a middle detachment unit plays an important role in connection to folding geometry, may be which is affected by Nezamabad main fault.

  7. A DEAD-box RNA helicase promotes thermodynamic equilibration of kinetically trapped RNA structures in vivo.

    PubMed

    Ruminski, Dana J; Watson, Peter Y; Mahen, Elisabeth M; Fedor, Martha J

    2016-03-01

    RNAs must assemble into specific structures in order to carry out their biological functions, but in vitro RNA folding reactions produce multiple misfolded structures that fail to exchange with functional structures on biological time scales. We used carefully designed self-cleaving mRNAs that assemble through well-defined folding pathways to identify factors that differentiate intracellular and in vitro folding reactions. Our previous work showed that simple base-paired RNA helices form and dissociate with the same rate and equilibrium constants in vivo and in vitro. However, exchange between adjacent secondary structures occurs much faster in vivo, enabling RNAs to quickly adopt structures with the lowest free energy. We have now used this approach to probe the effects of an extensively characterized DEAD-box RNA helicase, Mss116p, on a series of well-defined RNA folding steps in yeast. Mss116p overexpression had no detectable effect on helix formation or dissociation kinetics or on the stability of interdomain tertiary interactions, consistent with previous evidence that intracellular factors do not affect these folding parameters. However, Mss116p overexpression did accelerate exchange between adjacent helices. The nonprocessive nature of RNA duplex unwinding by DEAD-box RNA helicases is consistent with a branch migration mechanism in which Mss116p lowers barriers to exchange between otherwise stable helices by the melting and annealing of one or two base pairs at interhelical junctions. These results suggest that the helicase activity of DEAD-box proteins like Mss116p distinguish intracellular RNA folding pathways from nonproductive RNA folding reactions in vitro and allow RNA structures to overcome kinetic barriers to thermodynamic equilibration in vivo.

  8. A DEAD-box RNA helicase promotes thermodynamic equilibration of kinetically trapped RNA structures in vivo.

    PubMed

    Ruminski, Dana J; Watson, Peter Y; Mahen, Elisabeth M; Fedor, Martha J

    2016-03-01

    RNAs must assemble into specific structures in order to carry out their biological functions, but in vitro RNA folding reactions produce multiple misfolded structures that fail to exchange with functional structures on biological time scales. We used carefully designed self-cleaving mRNAs that assemble through well-defined folding pathways to identify factors that differentiate intracellular and in vitro folding reactions. Our previous work showed that simple base-paired RNA helices form and dissociate with the same rate and equilibrium constants in vivo and in vitro. However, exchange between adjacent secondary structures occurs much faster in vivo, enabling RNAs to quickly adopt structures with the lowest free energy. We have now used this approach to probe the effects of an extensively characterized DEAD-box RNA helicase, Mss116p, on a series of well-defined RNA folding steps in yeast. Mss116p overexpression had no detectable effect on helix formation or dissociation kinetics or on the stability of interdomain tertiary interactions, consistent with previous evidence that intracellular factors do not affect these folding parameters. However, Mss116p overexpression did accelerate exchange between adjacent helices. The nonprocessive nature of RNA duplex unwinding by DEAD-box RNA helicases is consistent with a branch migration mechanism in which Mss116p lowers barriers to exchange between otherwise stable helices by the melting and annealing of one or two base pairs at interhelical junctions. These results suggest that the helicase activity of DEAD-box proteins like Mss116p distinguish intracellular RNA folding pathways from nonproductive RNA folding reactions in vitro and allow RNA structures to overcome kinetic barriers to thermodynamic equilibration in vivo. PMID:26759451

  9. Optical dipole trapping of radium atoms for EDM search

    NASA Astrophysics Data System (ADS)

    Trimble, W. L.; Sulai, I. A.; Parker, R. H.; Bailey, K.; Greene, J. P.; Holt, R. J.; Korsch, W.; Lu, Z.-T.; Mueller, P.; O'Connor, T. P.; Singh, J.

    2010-03-01

    We are developing an EDM search based on laser-cooled and trapped Ra-225 (half-life = 15 d) atoms. Due to octupole deformation of the nucleus, Ra-225 is predicted to be 2-3 orders of magnitude more sensitive to T-violating interactions than Hg-199, which currently sets the most stringent limits in the nuclear sector. Recently, we have succeeded in transferring Ra-226 atoms from a MOT into an optical dipole trap formed by a fiber laser beam at 1550 nm. For the EDM measurement, the cold atoms will be moved into the neighboring vacuum chamber inside magnetic shields where a pair of electrodes apply a 10 kV cm-1electric field. This work is supported by DOE, Office of Nuclear Physics under contract No. DE-AC02-06CH11357.

  10. XAS study of mercury(II) ions trapped in mercaptan-functionalized mesostructured silicate with a wormhole framework structure.

    PubMed

    Chen, Chia-Chen; McKimmy, Emily J; Pinnavaia, Thomas J; Hayes, Kim F

    2004-09-15

    Directly assembled wormhole mesostructures with high level functionalized mercaptan (MP-HMS) have been shown to be effective mercury(II) (Hg2+) trapping agents. Sorption of Hg2+ onto MP-HMS was investigated using X-ray absorption spectroscopy (XAS) to identify the structural coordination of the adsorbed Hg. Samples with different fractions of mercaptan functionalized groups (i.e., x = 0.1 and 0.5) with various Hg/S molar ratios ranging from 0.05 to 1.4 were investigated. XAS analysis indicates that adsorbed Hg first coordination shell is best fitted with an Hg-O path and an Hg-S path. The Hg-S atomic distance (R(Hg-S)) remained relatively constant while the Hg-S coordination numbers (CN) decreased as Hg/S loading increased. For the Hg-O path, both the CN and the R(Hg-O) increased with increasing Hg loading. XAS results suggest that at low Hg loadings, adsorbed Hg2+ forms mostly monodentate sulfur complexes (-S-Hg-OH) with the sulfur functional groups on the MP-HMS surfaces. At high Hg loadings, the Hg coordination environment is consistent with the formation of a double-layer structure of Hg attached to sulfur binding sites (-S-Hg-O-Hg-OH).

  11. Non-Neutral Plasma Confinement In A Cusp-Trap And Possible Application To Anti-Hydrogen Beam Generation

    SciTech Connect

    Mohri, Akihiro; Kanai, Yasuyuki; Nakai, Yoichi; Yamazaki, Yasunori

    2005-10-19

    A new scheme for synthesizing antihydrogen by trapping positrons and antiprotons in a field consisting of a magnetic quadrupole and an electric octupole (cusp -trap) is now under investigation. The total electric field of the octupole with the space charge of a nonneutral plasma composed of particles of the same sign of charge, i.e., positrons or mixture of electrons and antiprotons, is expected to form a potential well for particles of the opposite sign of charge. Particles trapped in the well are mixed with the present dense particles, where positrons and antiprotons will combine to produce antihydrogen atoms. A considerable fraction of antihydrogen atoms in low-field seeking states will be transported outside as a beam.Experiments on electron confinement in the cusp-trap were carried out in a strong magnetic quadrupole (3.8T at the maximum on the axis). The confinement time reached 400s for the trapped electron number N0= 3.6x107. The time decreased with N0 but it was still about 100s for N0= 1.6x108.An electron plasma initially formed around the zero-field point rapidly expanded and settled down onto a quasi-stable state. Cross-sectional density profiles had shapes like a high volcano with a big crater. Analysis of the density profile shows that a potential well for oppositely charged particles (positive ions in this case) is probably formed inside the trapped electrons.

  12. New Aspects on the Structure of Neutrophil Extracellular Traps from Chronic Obstructive Pulmonary Disease and In Vitro Generation

    PubMed Central

    Krautgartner, Wolf-Dietrich; Klappacher, Michaela; Kofler, Barbara; Steinbacher, Peter; Vitkov, Ljubomir; Grabcanovic-Musija, Fikreta; Studnicka, Michael

    2014-01-01

    Polymorphonuclear neutrophils have in recent years attracted new attention due to their ability to release neutrophil extracellular traps (NETs). These web-like extracellular structures deriving from nuclear chromatin have been depicted in ambiguous roles between antimicrobial defence and host tissue damage. NETs consist of DNA strands of varying thickness and are decorated with microbicidal and cytotoxic proteins. Their principal structure has in recent years been characterised at molecular and ultrastructural levels but many features that are of direct relevance to cytotoxicity are still incompletely understood. These include the extent of chromatin decondensation during NET formation and the relative amounts and spatial distribution of the microbicidal components within the NET. In the present work, we analyse the structure of NETs found in induced sputum of patients with acutely exacerbated chronic obstructive pulmonary disease (COPD) using confocal laser microscopy and electron microscopy. In vitro induced NETs from human neutrophils serve for purposes of comparison and extended analysis of NET structure. Results demonstrate that COPD sputa are characterised by the pronounced presence of NETs and NETotic neutrophils. We provide new evidence that chromatin decondensation during NETosis is most extensive and generates substantial amounts of double-helix DNA in ‘beads-on-a-string’ conformation. New information is also presented on the abundance and location of neutrophil elastase (NE) and citrullinated histone H3 (citH3). NE occurs in high densities in nearly all non-fibrous constituents of the NETs while citH3 is much less abundant. We conclude from the results that (i) NETosis is an integral part of COPD pathology; this is relevant to all future research on the etiology and therapy of the disease; and that (ii) release of ‘beads-on-a-string’ DNA studded with non-citrullinated histones is a common feature of in vivo NETosis; this is of relevance to both

  13. New aspects on the structure of neutrophil extracellular traps from chronic obstructive pulmonary disease and in vitro generation.

    PubMed

    Obermayer, Astrid; Stoiber, Walter; Krautgartner, Wolf-Dietrich; Klappacher, Michaela; Kofler, Barbara; Steinbacher, Peter; Vitkov, Ljubomir; Grabcanovic-Musija, Fikreta; Studnicka, Michael

    2014-01-01

    Polymorphonuclear neutrophils have in recent years attracted new attention due to their ability to release neutrophil extracellular traps (NETs). These web-like extracellular structures deriving from nuclear chromatin have been depicted in ambiguous roles between antimicrobial defence and host tissue damage. NETs consist of DNA strands of varying thickness and are decorated with microbicidal and cytotoxic proteins. Their principal structure has in recent years been characterised at molecular and ultrastructural levels but many features that are of direct relevance to cytotoxicity are still incompletely understood. These include the extent of chromatin decondensation during NET formation and the relative amounts and spatial distribution of the microbicidal components within the NET. In the present work, we analyse the structure of NETs found in induced sputum of patients with acutely exacerbated chronic obstructive pulmonary disease (COPD) using confocal laser microscopy and electron microscopy. In vitro induced NETs from human neutrophils serve for purposes of comparison and extended analysis of NET structure. Results demonstrate that COPD sputa are characterised by the pronounced presence of NETs and NETotic neutrophils. We provide new evidence that chromatin decondensation during NETosis is most extensive and generates substantial amounts of double-helix DNA in 'beads-on-a-string' conformation. New information is also presented on the abundance and location of neutrophil elastase (NE) and citrullinated histone H3 (citH3). NE occurs in high densities in nearly all non-fibrous constituents of the NETs while citH3 is much less abundant. We conclude from the results that (i) NETosis is an integral part of COPD pathology; this is relevant to all future research on the etiology and therapy of the disease; and that (ii) release of 'beads-on-a-string' DNA studded with non-citrullinated histones is a common feature of in vivo NETosis; this is of relevance to both the

  14. Structure analysis of triterpene saponins in Polygala tenuifolia by electrospray ionization ion trap multiple-stage mass spectrometry.

    PubMed

    Liu, Jiangyun; Yang, Xuedong; He, Jiuming; Xia, Min; Xu, Lizhen; Yang, Shilin

    2007-07-01

    Eighteen different triterpene saponins isolated from Polygala tenuifolia were investigated by electrospray ionization ion trap multiple-stage mass spectrometry (ESI-ITMS(n)) in positive and negative ion modes. MS(1)-MS(3)/MS(4) spectra of the both modes were analyzed, and they all gave fragments in line and shared common fragmentation patterns. Key fragments from MS(n) spectra of both the modes and their proposed fragmentation pathways were constructed with examples illustrated for the formation of characteristic fragments in the saponins. Two special fragmentation patterns were proposed: (1) the formation of fragments by cleavage of CH(2)O from Delta(12)-14alpha-CH(2)OH of the oleanene-type saponin aglycone in both positive and negative MS(n) (n > or = 2) modes; (2) the occurrence of fragments by cleavage of CO(2) and 3-glucose as the characteristic structure feature of 23-COOH at the oleanene-type saponin aglycones coupled with 3-Glc substitutes in the negative MS(n) (n > or = 2) modes. Peak intensities in MS(n) spectra were also correlated with structural features and fragmentation preferences of the investigated saponins, which are discussed in detail. In general, fragments formed predominantly by cleavages of glycosidic bonds in the positive mode, while selective cleavages of acyl bonds preceded that of glycosidic bonds in negative MS(n) (n > or = 2) mode, both of which could well be applied to the structural analysis of these saponins. Interpretation of MS(n) spectra presented here provided diagnostic key fragment ions important for the structural elucidation of saponins in P.tenuifolia.

  15. Evolution of the hourglass structures in the Laminaria High, Timor Sea: Implications for hydrocarbon traps

    NASA Astrophysics Data System (ADS)

    Çiftçi, N. Bozkurt; Langhi, Laurent

    2012-03-01

    In cross-section, an hourglass structure can be visualized as an older horst block and superimposed, younger graben. Bounding faults of the horst and graben blocks represent separate conjugate fault systems formed by two distinct episodes of extension in the Timor Sea during Late Jurassic-Early Cretaceous (1st-phase) and Middle Miocene - Pliocene (2nd-phase); with an ∼120 My hiatus of limited or no fault activity in-between. Horst blocks were formed by the 1st-phase of extension and buried post-deformation. With the onset of the 2nd-phase of extension, the hourglass geometry began to form by nucleation of the graben-bounding faults in the shallow sedimentary section, in isolation from the horst-bounding faults. Location of the graben is biased by the buried horst block and graben-bounding faults grew down-dip from the shallow locus of nucleation toward the underlying horst block on which only minor reactivation occurred. Detachment of the two systems in this way was predominantly controlled by the first-order mechanical layering. A thick, shale-rich, ductile layer separates the horst- and graben-bounding fault systems and acts as a barrier to vertical fault propagation. Confinement of the graben-bounding faults into the shallow section was also facilitated by outer-arc style extension due to lithospheric flexure controlling the 2nd-phase strain in the region. The complex evolution history and the composite nature of the hourglass structures resulted in systematic along-dip variation of displacement. This variation predominantly relates to syn-kinematic deposition and location of fault tips that are controlled by the ductile layer. The presented evolution model of the hourglass structures concentrates fault tips and related stress perturbation onto the top seal and is likely to be detrimental to top-seal integrity.

  16. Laser trapping of Ra-225 and Ra-226 and progress towards an electric dipole moment measurement

    NASA Astrophysics Data System (ADS)

    Guest, J. R.; Scielzo, N. D.; Ahmad, I.; Bailey, K.; Greene, J. P.; Holt, R. J.; Lu, Z.-T.; O'Connor, T. P.; Potterveld, D. H.

    2006-10-01

    Permanent electric dipole moments (EDMs) in atoms or molecules are signatures of Time (T)-and Parity (P)-violation and represent an important window onto physics beyond the Standard Model. We are developing a next generation EDM search around laser-cooled and trapped Ra-225 (t1/2 = 15 d). Due to octupole deformation of the nucleus, Ra-225 is predicted to be two to three orders of magnitude more sensitive to T-violating interactions than Hg-199, which currently sets the most stringent limits in the nuclear sector. We will discuss our progress, including the successful laser cooling and trapping of Ra-225 and Ra-226 atoms. We have demonstrated transverse cooling, Zeeman slowing, and capture of Ra-225 and Ra-226 atoms in a magneto-optical trap (MOT). By driving a second atomic transition, we have extended the lifetime of the trap from milliseconds to seconds and performed necessary spectroscopic measurements.

  17. Structural characterization of toxic oligomers that are kinetically trapped during α-synuclein fibril formation.

    PubMed

    Chen, Serene W; Drakulic, Srdja; Deas, Emma; Ouberai, Myriam; Aprile, Francesco A; Arranz, Rocío; Ness, Samuel; Roodveldt, Cintia; Guilliams, Tim; De-Genst, Erwin J; Klenerman, David; Wood, Nicholas W; Knowles, Tuomas P J; Alfonso, Carlos; Rivas, Germán; Abramov, Andrey Y; Valpuesta, José María; Dobson, Christopher M; Cremades, Nunilo

    2015-04-21

    We describe the isolation and detailed structural characterization of stable toxic oligomers of α-synuclein that have accumulated during the process of amyloid formation. Our approach has allowed us to identify distinct subgroups of oligomers and to probe their molecular architectures by using cryo-electron microscopy (cryoEM) image reconstruction techniques. Although the oligomers exist in a range of sizes, with different extents and nature of β-sheet content and exposed hydrophobicity, they all possess a hollow cylindrical architecture with similarities to certain types of amyloid fibril, suggesting that the accumulation of at least some forms of amyloid oligomers is likely to be a consequence of very slow rates of rearrangement of their β-sheet structures. Our findings reveal the inherent multiplicity of the process of protein misfolding and the key role the β-sheet geometry acquired in the early stages of the self-assembly process plays in dictating the kinetic stability and the pathological nature of individual oligomeric species.

  18. Structural characterization of toxic oligomers that are kinetically trapped during α-synuclein fibril formation

    PubMed Central

    Chen, Serene W.; Drakulic, Srdja; Deas, Emma; Ouberai, Myriam; Aprile, Francesco A.; Arranz, Rocío; Ness, Samuel; Roodveldt, Cintia; Guilliams, Tim; De-Genst, Erwin J.; Klenerman, David; Wood, Nicholas W.; Knowles, Tuomas P.J.; Alfonso, Carlos; Rivas, Germán; Abramov, Andrey Y.; Valpuesta, José María; Dobson, Christopher M.; Cremades, Nunilo

    2015-01-01

    We describe the isolation and detailed structural characterization of stable toxic oligomers of α-synuclein that have accumulated during the process of amyloid formation. Our approach has allowed us to identify distinct subgroups of oligomers and to probe their molecular architectures by using cryo-electron microscopy (cryoEM) image reconstruction techniques. Although the oligomers exist in a range of sizes, with different extents and nature of β-sheet content and exposed hydrophobicity, they all possess a hollow cylindrical architecture with similarities to certain types of amyloid fibril, suggesting that the accumulation of at least some forms of amyloid oligomers is likely to be a consequence of very slow rates of rearrangement of their β-sheet structures. Our findings reveal the inherent multiplicity of the process of protein misfolding and the key role the β-sheet geometry acquired in the early stages of the self-assembly process plays in dictating the kinetic stability and the pathological nature of individual oligomeric species. PMID:25855634

  19. Trapping Effect of Periodic Structures on the Thermodynamic Properties of a Fermi Gas

    NASA Astrophysics Data System (ADS)

    Salas, P.; Solís, M. A.

    2014-04-01

    We report the thermodynamic properties of an ideal Fermi gas immersed in periodic structures such as penetrable multilayers or multitubes simulated by one (planes) or two perpendicular (tubes) external Dirac comb potentials, while the particles are allowed to move freely in the remaining directions. In contrast to what happens to the bosonic chemical potential, which is a constant for T< T c , a non decreasing with temperature anomalous behavior of the fermionic chemical potential is confirmed and monitored as the tube bundle goes from 3D to 1D when the wall impenetrability overcomes a threshold value. In the specific heat curves dimensional crossovers are very noticeable at high temperatures, where the system behavior goes from 3D to 2D for multilayers or from 3D to 1D for multitubes, as the wall impenetrability is increased.

  20. Two-dimensional binary clusters in a hard-wall trap: Structural and spectral properties

    SciTech Connect

    Yang Wen; Kong Minghui; Milosevic, M. V.; Zeng Zhi; Peeters, F. M.

    2007-10-15

    Within the Monte Carlo formalism supplemented by the modified Newton-Raphson optimization technique, we investigated structural and dynamical properties of two-dimensional binary clusters confined in an external hard-wall potential. Two species of differently charged classical particles, interacting through the repulsive Coulomb force are confined in the cluster. Subtle changes in the energy landscape and the stable cluster configurations are investigated as a function of the total number of particles and the relative number of each of the two particle species. The excitation spectrum and the normal modes corresponding to the ground-state configuration of the system are discussed, and the lowest nonzero eigenfrequency as a measure of the stability of the cluster is analyzed. The influence of the particle mass on the eigenfrequencies and eigenmodes are studied, i.e., we study a binary system of particles with different charge and different mass. Several unique features distinct from a monodisperse system are obtained.

  1. Safe trapping of cesium into pollucite structure by hot-pressing method

    NASA Astrophysics Data System (ADS)

    Omerašević, Mia; Matović, Ljiljana; Ružić, Jovana; Golubović, Željko; Jovanović, Uroš; Mentus, Slavko; Dondur, Vera

    2016-06-01

    A simple one-step method with direct thermal conversion at lower temperatures for preparing a stabile Cs-aluminsilicate phase, known as pollucite, is presented. Cs-exchanged form of Na, Ca-LTA type of zeolite (Cs-LTA) was pressureless sintered and hot pressed at certain temperatures in order to obtain pollucite. XRD and FTIR analysis were used to study structural changes of Cs-LTA before and after thermal treatments. Pressureless sintered sample recrystallized into pollucite phase after heat treatment at 1000 °C (3 h) (PLS1000) and hot pressed sample at 750 °C (3 h) using pressure of 35 MPa (HP750), indicating reduced temperature of 250°. SEM micrographs confirmed that HP750 has higher density than PLS1000 which leads to higher value of compressive strength. The HP750 showed better resistance to Cs leaching than the PLS1000. Base on these results one can conclude that hot pressing is the promising method for the permanent disposal of Cs radionuclides.

  2. Protected Light-Trapping Silicon by a Simple Structuring Process for Sunlight-Assisted Water Splitting.

    PubMed

    Santinacci, Lionel; Diouf, Maïmouna W; Barr, Maïssa K S; Fabre, Bruno; Joanny, Loïc; Gouttefangeas, Francis; Loget, Gabriel

    2016-09-21

    Macroporous layers are grown onto n-type silicon by successive photoelectrochemical etching in HF-containing solution and chemical etching in KOH. This specific latter treatment gives highly antireflective properties of the Si surface. The duration of the chemical etching is optimized to render the surface as absorbent as possible, and the morphology of the as-grown layer is characterized by scanning electron microscopy. Further functionalization of such structured Si surface is carried out by atomic layer deposition of a thin conformal and homogeneous TiO2 layer that is crystallized by an annealing at 450 °C. This process allows using such surfaces as photoanodes for water oxidation. The 40 nm thick TiO2 film acts indeed as an efficient protective layer against the photocorrosion of the porous Si in KOH, enhances its wettability, and improves the light absorption of the photoelectrode. The macroporous dual-absorber TiO2/Si has a beneficial effect on water oxidation in 1 M KOH and leads to a considerable negative shift of the onset potential of ∼400 mV as well as a 50% increase in photocurrent at 1 V vs SCE. PMID:27575424

  3. Structure and trapping of three-dimensional dust clouds in a capacitively coupled rf-discharge

    SciTech Connect

    Arp, O.; Block, D.; Piel, A.

    2005-10-31

    In this survey the recently found 'Coulomb balls' are discussed, which show an unusual kind of crystalline order. These three-dimensional dust clouds consisting of hundreds or thousands of micrometer-sized dust particles have a spherical shape and exist in a wide range of plasma conditions. Coulomb balls are optically highly transparent and have macroscopic dimensions of several millimeters in diameter. The clouds allow for the observation of each single particle and thus the complete reconstruction of the crystal structure by means of video microscopy techniques. The particles are arranged in distinct nested shells in which they form patterns with mostly five and six neighbors. The confinement of Coulomb balls by dielectric walls involves electric forces, surface charges, ion drag forces, and thermophoretic levitation. The thermophoretic force field is measured with tracer particles and particle image velocimetry (PIV). The electric forces are derived from simulations with the two-dimensional SIGLO-2D code. It is shown the the sum of all confining forces results in a stable potential well that describes levitation and spherical confinement of the Coulomb ball.

  4. Protected Light-Trapping Silicon by a Simple Structuring Process for Sunlight-Assisted Water Splitting.

    PubMed

    Santinacci, Lionel; Diouf, Maïmouna W; Barr, Maïssa K S; Fabre, Bruno; Joanny, Loïc; Gouttefangeas, Francis; Loget, Gabriel

    2016-09-21

    Macroporous layers are grown onto n-type silicon by successive photoelectrochemical etching in HF-containing solution and chemical etching in KOH. This specific latter treatment gives highly antireflective properties of the Si surface. The duration of the chemical etching is optimized to render the surface as absorbent as possible, and the morphology of the as-grown layer is characterized by scanning electron microscopy. Further functionalization of such structured Si surface is carried out by atomic layer deposition of a thin conformal and homogeneous TiO2 layer that is crystallized by an annealing at 450 °C. This process allows using such surfaces as photoanodes for water oxidation. The 40 nm thick TiO2 film acts indeed as an efficient protective layer against the photocorrosion of the porous Si in KOH, enhances its wettability, and improves the light absorption of the photoelectrode. The macroporous dual-absorber TiO2/Si has a beneficial effect on water oxidation in 1 M KOH and leads to a considerable negative shift of the onset potential of ∼400 mV as well as a 50% increase in photocurrent at 1 V vs SCE.

  5. Artificially Structured Boundary for a high purity ion trap or ion source

    NASA Astrophysics Data System (ADS)

    Pacheco, J. L.; Ordonez, C. A.; Weathers, D. L.

    2014-08-01

    A plasma enclosed by an Artificially Structured Boundary (ASB) is proposed here as an alternative to existing ion source assemblies. In accelerator applications, many ion sources can have a limited lifetime or frequent service intervals due to sputtering and eventual degradation of the ion source assembly. Ions are accelerated towards the exit canal of positive ion sources, whereas, due to the biasing scheme, electrons or negative ions are accelerated towards the back of the ion source assembly. This can either adversely affect the experiment in progress due to sputtered contamination or compromise the integrity of the ion source assembly. Charged particle trajectories in the proximity of an ASB experience electromagnetic fields that are designed to hinder ion-surface interactions. Away from the ASB there is an essentially field free region. The field produced by an ASB is considered to consist of a periodic sequence of electrostatically plugged magnetic field cusps. A classical trajectory Monte Carlo simulation is extended to include electrostatic plugging of magnetic field cusps. The conditions necessary for charged particles to be reflected by the ASB are presented and quantified in terms of normalized parameters.

  6. Crystal Structures of Nitroalkane Oxidase: Insights into the Reaction Mechanism of a Covalent Complex of the Flavoenzyme Trapped During Turnover

    SciTech Connect

    Nagpal,A.; Valley, M.; Fitzpatrick, P.; Orville, A.

    2006-01-01

    Nitroalkane oxidase (NAO) from Fusarium oxysporum catalyzes the oxidation of neutral nitroalkanes to the corresponding aldehydes or ketones with the production of H2O2 and nitrite. The flavoenzyme is a new member of the acyl-CoA dehydrogenase (ACAD) family, but it does not react with acyl-CoA substrates. We present the 2.2 Angstroms resolution crystal structure of NAO trapped during the turnover of nitroethane as a covalent N5-FAD adduct (ES*). The homotetrameric structure of ES* was solved by MAD phasing with 52 Se-Met sites in an orthorhombic space group. The electron density for the N5-(2-nitrobutyl)-1,5-dihydro-FAD covalent intermediate is clearly resolved. The structure of ES* was used to solve the crystal structure of oxidized NAO at 2.07 Angstroms resolution. The c axis for the trigonal space group of oxidized NAO is 485 Angstroms, and there are six subunits (11/2 holoenzymes) in the asymmetric unit. Four of the active sites contain spermine (EI), a weak competitive inhibitor, and two do not contain spermine (E{sup ox}). The active-site structures of E{sup ox}, EI, and ES* reveal a hydrophobic channel that extends from the exterior of the protein and terminates at Asp402 and the N5 position on the re face of the FAD. Thus, Asp402 is in the correct position to serve as the active-site base, where it is proposed to abstract the {alpha} proton from neutral nitroalkane substrates. The structures for NAO and various members of the ACAD family overlay with root-mean-square deviations between 1.7 and 3.1 Angstroms. The homologous region typically spans more than 325 residues and includes Glu376, which is the active-site base in the prototypical member of the ACAD family. However, NAO and the ACADs exhibit differences in hydrogen-bonding patterns between the respective active-site base, substrate molecules, and FAD. These likely differentiate NAO from the homologues and, consequently, are proposed to result in the unique reaction mechanism of NAO.

  7. Evidence for octupole vibration in the superdeformed well of {sup 190}Hg from eurogam

    SciTech Connect

    Crowell, B.; Carpenter, M.P.; Janssens, R.V.F.

    1995-08-01

    Gammasphere experiments in 1993-94 brought to light the existence of an excited superdeformed (SD) band in {sup 190}Hg with the unusual property of decaying entirely to the lowest (yrast) SD band over 3-4 transitions, rather than to the normally deformed states as is usually the case in the A {approximately} 150 and A {approximately} 190 regions of superdeformation. Although M1 transitions between signature-partner SD bands were previously observed in {sup 193}Hg, no such mechanism was available to explain the situation in the even-even nucleus {sup 190}Hg, whose yrast SD band has no signature partner. The best explanation appears to lie in long-standing theoretical predictions that the SD minimum in the potential energy surface would be quite soft with respect to octupole vibrations. This would lead to enhanced E1 transitions connecting the one-phonon and zero-phonon states. The data and this interpretation were published. A shortcoming of the Gammasphere experiments was that they did not allow the definitive measurement of the energies of the gamma-ray transitions connecting the two bands, due to the very weak population of the excited band ({approximately}0.05% of the {sup 190}Hg channel) and also partly, we believed, to the angular distributions of the transitions, which were peaked near 90 degrees, where Gammasphere had few detectors.

  8. Oxygen trapped by rare earth tetrahedral clusters in Nd4FeOS6: Crystal structure, electronic structure, and magnetic properties

    DOE PAGES

    Lin, Qisheng; Taufour, Valentin; Zhang, Yuemei; Wood, Max; Drtina, Thomas; Bud’ko, Sergey L.; Canfield, Paul C.; Miller, Gordon J.

    2015-05-22

    Single crystals of Nd4FeOS6 were grown from an Fe-S eutectic solution. Single crystal X-ray diffraction analysis revealed a Nd4MnOSe6-type structure (P63mc, a = 9.2693(1) Å, c = 6.6650(1) Å, V = 495.94(1) Å3, Z = 2), featuring parallel chains of face-sharing [FeS6x1/2]4- trigonal antiprisms and interlinked [Nd4OS3]4+ cubane-like clusters. Oxygen atoms were found to be trapped by Nd4 clusters in the [Nd4OS3]4+ chains. Structural differences among Nd4MnOSe6-type Nd4FeOS6 and the related La3CuSiS7- and Pr8CoGa3-type structures have been described. Magnetic susceptibility measurements on Nd4FeOS6 suggested the dominance of antiferromagnetic interactions at low temperature, but no magnetic ordering down to 2 Kmore » was observed. Spin-polarized electronic structure calculations revealed magnetic frustration with dominant antiferromagnetic interactions.« less

  9. Effects of pitfall trap lid transparency and habitat structure on the catches of carabid beetles (Coleoptera: Carabidae) in tame pasture.

    PubMed

    Bell, Aaron J; Phillips, Iain D; Floate, Kevin D; Hoemsen, Brittney M; Phillips, Colin E

    2014-02-01

    Captures of insects in pitfall traps are affected by features of trap design that may confound the interpretation of data. One such feature is a lid suspended over the opening of the trap to exclude debris and rainwater. In this study, we tested whether use of these lids affected captures of carabid beetles by altering the light conditions at the opening to the trap. In one experiment, we examined the effects of lid transparency (opaque, semitransparent, or transparent) on catch rates. In a second experiment, we manipulated the heights (high, medium, or low) of vegetation adjacent to the traps to test for lid transparency and vegetation height interactions. We found that significantly more carabids were captured with use of transparent lids compared with other lid transparencies. Fewest Agonum cupreum Dejean, 1831, were captured with use of opaque lids. No other effects were detected. Given these results, we advocate the use of transparent lids, which provide the benefits of traditional opaque lids while minimizing the effects of lid use on light conditions at the opening to the trap.

  10. Trapped Antihydrogen

    NASA Astrophysics Data System (ADS)

    Robicheaux, Francis

    2012-03-01

    Atoms made of a particle and an antiparticle are unstable, usually surviving less than a microsecond. Antihydrogen, the bound state of an antiproton and a positron, is made entirely of antiparticles and is believed to be stable. It is this longevity that holds the promise of precision studies of matter-antimatter symmetry. Low energy (Kelvin scale) antihydrogen has been produced at CERN since 2002. I will describe the experiment which has recently succeeded in trapping antihydrogen in a cryogenic Penning trap for times up to approximately 15 minutes.

  11. Coupled optical-thermal-fluid and structural analyses of novel light-trapping tubular panels for concentrating solar power receivers

    NASA Astrophysics Data System (ADS)

    Ortega, Jesus D.; Christian, Joshua M.; Yellowhair, Julius E.; Ho, Clifford K.

    2015-09-01

    Traditional tubular receivers used in concentrating solar power are formed using tubes connected to manifolds to form panels; which in turn are arranged in cylindrical or rectangular shapes. Previous and current tubular receivers, such as the ones used in Solar One, Solar Two, and most recently the Ivanpah solar plants, have used a black paint coating to increase the solar absorptance of the receiver. However, these coatings degrade over time and must be reapplied, increasing the receiver maintenance cost. This paper presents the thermal efficiency evaluation of novel receiver tubular panels that have a higher effective solar absorptance due to a light-trapping effect created by arranging the tubes in each panel into unique geometric configurations. Similarly, the impact of the incidence angle on the effective solar absorptance and thermal efficiency is evaluated. The overarching goal of this work is to achieve effective solar absorptances of ~90% and thermal efficiencies above 85% without using an absorptance coating. Several panel geometries were initially proposed and were down-selected based on structural analyses considering the thermal and pressure loading requirements of molten salt and supercritical carbon-dioxide receivers. The effective solar absorptance of the chosen tube geometries and panel configurations were evaluated using the ray-tracing modeling capabilities of SolTrace. The thermal efficiency was then evaluated by coupling computational fluid dynamics with the ray-tracing results using ANSYS Fluent. Compared to the base case analysis (flat tubular panel), the novel tubular panels have shown an increase in effective solar absorptance and thermal efficiency by several percentage points.

  12. Structural and thermodynamic characterization of the interaction between two periplasmic Treponema pallidum lipoproteins that are components of a TPR-protein-associated TRAP transporter (TPAT)

    PubMed Central

    Brautigam, Chad A.; Deka, Ranjit K.; Schuck, Peter; Tomchick, Diana R.; Norgard, Michael V.

    2012-01-01

    Tripartite ATP-independent periplasmic transporters (TRAP-Ts) are bacterial transport systems that have been implicated in the import of small molecules into the cytoplasm. A newly discovered subfamily of TRAP-Ts (TPATs) has four components. Three are common to both TRAP-Ts and TPATs: the P component, a ligand-binding protein, and a transmembrane symporter apparatus comprising the M and Q components (M and Q are sometimes fused to form a single polypeptide). TPATs are distinguished from TRAP-Ts by the presence of a unique protein called the “T component”. In Treponema pallidum, this protein (TatT) is a water-soluble trimer whose protomers are each perforated by a pore. Its respective P component (TatPT) interacts with the TatT in vitro and in vivo. In this work, we further characterized this interaction. Co-crystal structures of two complexes between the two proteins confirm that up to three monomers of TatPT can bind to the TatT trimer. A putative ligand-binding cleft of TatPT aligns with the pore of TatT, strongly suggesting ligand transfer between T and PT. We used a combination of site-directed mutagenesis and analytical ultracentrifugation to derive thermodynamic parameters for the interactions. These observations confirm that the observed crystallographic interface is recapitulated in solution. These results prompt a hypothesis of the molecular mechanism(s) of hydrophobic ligand transport by the TPATs. PMID:22504226

  13. Broadband perfect light trapping in the thinnest monolayer graphene-MoS2 photovoltaic cell: the new application of spectrum-splitting structure

    PubMed Central

    Wu, Yun-Ben; Yang, Wen; Wang, Tong-Biao; Deng, Xin-Hua; Liu, Jiang-Tao

    2016-01-01

    The light absorption of a monolayer graphene-molybdenum disulfide photovoltaic (GM-PV) cell in a wedge-shaped microcavity with a spectrum-splitting structure is investigated theoretically. The GM-PV cell, which is three times thinner than the traditional photovoltaic cell, exhibits up to 98% light absorptance in a wide wavelength range. This rate exceeds the fundamental limit of nanophotonic light trapping in solar cells. The effects of defect layer thickness, GM-PV cell position in the microcavity, incident angle, and lens aberration on the light absorptance of the GM-PV cell are explored. Despite these effects, the GM-PV cell can still achieve at least 90% light absorptance with the current technology. Our proposal provides different methods to design light-trapping structures and apply spectrum-splitting systems. PMID:26864749

  14. Broadband perfect light trapping in the thinnest monolayer graphene-MoS2 photovoltaic cell: the new application of spectrum-splitting structure.

    PubMed

    Wu, Yun-Ben; Yang, Wen; Wang, Tong-Biao; Deng, Xin-Hua; Liu, Jiang-Tao

    2016-01-01

    The light absorption of a monolayer graphene-molybdenum disulfide photovoltaic (GM-PV) cell in a wedge-shaped microcavity with a spectrum-splitting structure is investigated theoretically. The GM-PV cell, which is three times thinner than the traditional photovoltaic cell, exhibits up to 98% light absorptance in a wide wavelength range. This rate exceeds the fundamental limit of nanophotonic light trapping in solar cells. The effects of defect layer thickness, GM-PV cell position in the microcavity, incident angle, and lens aberration on the light absorptance of the GM-PV cell are explored. Despite these effects, the GM-PV cell can still achieve at least 90% light absorptance with the current technology. Our proposal provides different methods to design light-trapping structures and apply spectrum-splitting systems. PMID:26864749

  15. Broadband perfect light trapping in the thinnest monolayer graphene-MoS2 photovoltaic cell: the new application of spectrum-splitting structure

    NASA Astrophysics Data System (ADS)

    Wu, Yun-Ben; Yang, Wen; Wang, Tong-Biao; Deng, Xin-Hua; Liu, Jiang-Tao

    2016-02-01

    The light absorption of a monolayer graphene-molybdenum disulfide photovoltaic (GM-PV) cell in a wedge-shaped microcavity with a spectrum-splitting structure is investigated theoretically. The GM-PV cell, which is three times thinner than the traditional photovoltaic cell, exhibits up to 98% light absorptance in a wide wavelength range. This rate exceeds the fundamental limit of nanophotonic light trapping in solar cells. The effects of defect layer thickness, GM-PV cell position in the microcavity, incident angle, and lens aberration on the light absorptance of the GM-PV cell are explored. Despite these effects, the GM-PV cell can still achieve at least 90% light absorptance with the current technology. Our proposal provides different methods to design light-trapping structures and apply spectrum-splitting systems.

  16. Broadband perfect light trapping in the thinnest monolayer graphene-MoS2 photovoltaic cell: the new application of spectrum-splitting structure.

    PubMed

    Wu, Yun-Ben; Yang, Wen; Wang, Tong-Biao; Deng, Xin-Hua; Liu, Jiang-Tao

    2016-02-11

    The light absorption of a monolayer graphene-molybdenum disulfide photovoltaic (GM-PV) cell in a wedge-shaped microcavity with a spectrum-splitting structure is investigated theoretically. The GM-PV cell, which is three times thinner than the traditional photovoltaic cell, exhibits up to 98% light absorptance in a wide wavelength range. This rate exceeds the fundamental limit of nanophotonic light trapping in solar cells. The effects of defect layer thickness, GM-PV cell position in the microcavity, incident angle, and lens aberration on the light absorptance of the GM-PV cell are explored. Despite these effects, the GM-PV cell can still achieve at least 90% light absorptance with the current technology. Our proposal provides different methods to design light-trapping structures and apply spectrum-splitting systems.

  17. Direct observation of kinetic traps associated with structural transformations leading to multiple pathways of S-layer assembly.

    PubMed

    Shin, Seong-Ho; Chung, Sungwook; Sanii, Babak; Comolli, Luis R; Bertozzi, Carolyn R; De Yoreo, James J

    2012-08-01

    The concept of a folding funnel with kinetic traps describes folding of individual proteins. Using in situ Atomic Force Microscopy to investigate S-layer assembly on mica, we show this concept is equally valid during self-assembly of proteins into extended matrices. We find the S-layer-on-mica system possesses a kinetic trap associated with conformational differences between a long-lived transient state and the final stable state. Both ordered tetrameric states emerge from clusters of the monomer phase, however, they then track along two different pathways. One leads directly to the final low-energy state and the other to the kinetic trap. Over time, the trapped state transforms into the stable state. By analyzing the time and temperature dependencies of formation and transformation we find that the energy barriers to formation of the two states differ by only 0.7 kT, but once the high-energy state forms, the barrier to transformation to the low-energy state is 25 kT. Thus the transient state exhibits the characteristics of a kinetic trap in a folding funnel. PMID:22822216

  18. Direct observation of kinetic traps associated with structural transformations leading to multiple pathways of S-layer assembly

    PubMed Central

    Shin, Seong-Ho; Chung, Sungwook; Sanii, Babak; Comolli, Luis R.; Bertozzi, Carolyn R.; De Yoreo, James J.

    2012-01-01

    The concept of a folding funnel with kinetic traps describes folding of individual proteins. Using in situ Atomic Force Microscopy to investigate S-layer assembly on mica, we show this concept is equally valid during self-assembly of proteins into extended matrices. We find the S-layer-on-mica system possesses a kinetic trap associated with conformational differences between a long-lived transient state and the final stable state. Both ordered tetrameric states emerge from clusters of the monomer phase, however, they then track along two different pathways. One leads directly to the final low-energy state and the other to the kinetic trap. Over time, the trapped state transforms into the stable state. By analyzing the time and temperature dependencies of formation and transformation we find that the energy barriers to formation of the two states differ by only 0.7 kT, but once the high-energy state forms, the barrier to transformation to the low-energy state is 25 kT. Thus the transient state exhibits the characteristics of a kinetic trap in a folding funnel. PMID:22822216

  19. Percolation mechanism through trapping/de-trapping process at defect states for resistive switching devices with structure of Ag/Si{sub x}C{sub 1−x}/p-Si

    SciTech Connect

    Liu, Yanhong; Gao, Ping; Li, La; Peng, Wei; Jiang, Xuening; Zhang, Jialiang

    2014-08-14

    Pure Si{sub x}C{sub 1−x} (x > 0.5) and B-containing Si{sub x}C{sub 1−x} (x > 0.5) based resistive switching devices (RSD) with the structure of Ag/Si{sub x}C{sub 1−x}/p-Si were fabricated and their switching characteristics and mechanism were investigated systematically. Percolation mechanism through trapping/ de-trapping at defect states was suggested for the switching process. Through the introduction of B atoms into Si{sub x}C{sub 1−x}, the density of defect states was reduced, then, the SET and RESET voltages were also decreased. Based on the percolation theory, the dependence of SET/RESET voltage on the density of defect states was analyzed. These results supply a deep understanding for the SiC-based RSD, which have a potential application in extreme ambient conditions.

  20. Oxygen trapped by rare earth tetrahedral clusters in Nd4FeOS6: Crystal structure, electronic structure, and magnetic properties

    SciTech Connect

    Lin, Qisheng; Taufour, Valentin; Zhang, Yuemei; Wood, Max; Drtina, Thomas; Bud’ko, Sergey L.; Canfield, Paul C.; Miller, Gordon J.

    2015-05-22

    Single crystals of Nd4FeOS6 were grown from an Fe-S eutectic solution. Single crystal X-ray diffraction analysis revealed a Nd4MnOSe6-type structure (P63mc, a = 9.2693(1) Å, c = 6.6650(1) Å, V = 495.94(1) Å3, Z = 2), featuring parallel chains of face-sharing [FeS6x1/2]4- trigonal antiprisms and interlinked [Nd4OS3]4+ cubane-like clusters. Oxygen atoms were found to be trapped by Nd4 clusters in the [Nd4OS3]4+ chains. Structural differences among Nd4MnOSe6-type Nd4FeOS6 and the related La3CuSiS7- and Pr8CoGa3-type structures have been described. Magnetic susceptibility measurements on Nd4FeOS6 suggested the dominance of antiferromagnetic interactions at low temperature, but no magnetic ordering down to 2 K was observed. Spin-polarized electronic structure calculations revealed magnetic frustration with dominant antiferromagnetic interactions.

  1. Structural and thermodynamic characterization of the interaction between two periplasmic Treponema pallidum lipoproteins that are components of a TPR-protein-associated TRAP transporter (TPAT).

    PubMed

    Brautigam, Chad A; Deka, Ranjit K; Schuck, Peter; Tomchick, Diana R; Norgard, Michael V

    2012-06-29

    Tripartite ATP-independent periplasmic transporters (TRAP-Ts) are bacterial transport systems that have been implicated in the import of small molecules into the cytoplasm. A newly discovered subfamily of TRAP-Ts [tetratricopeptide repeat-protein associated TRAP transporters (TPATs)] has four components. Three are common to both TRAP-Ts and TPATs: the P component, a ligand-binding protein, and a transmembrane symporter apparatus comprising the M and Q components (M and Q are sometimes fused to form a single polypeptide). TPATs are distinguished from TRAP-Ts by the presence of a unique protein called the "T component". In Treponema pallidum, this protein (TatT) is a water-soluble trimer whose protomers are each perforated by a pore. Its respective P component (TatP(T)) interacts with the TatT in vitro and in vivo. In this work, we further characterized this interaction. Co-crystal structures of two complexes between the two proteins confirm that up to three monomers of TatP(T) can bind to the TatT trimer. A putative ligand-binding cleft of TatP(T) aligns with the pore of TatT, strongly suggesting ligand transfer between T and P(T). We used a combination of site-directed mutagenesis and analytical ultracentrifugation to derive thermodynamic parameters for the interactions. These observations confirm that the observed crystallographic interface is recapitulated in solution. These results prompt a hypothesis of the molecular mechanism(s) of hydrophobic ligand transport by the TPATs. PMID:22504226

  2. Cosmic flows on 100 h-1 Mpc scales: standardized minimum variance bulk flow, shear and octupole moments

    NASA Astrophysics Data System (ADS)

    Feldman, Hume A.; Watkins, Richard; Hudson, Michael J.

    2010-10-01

    The low-order moments, such as the bulk flow and shear, of the large-scale peculiar velocity field are sensitive probes of the matter density fluctuations on very large scales. In practice, however, peculiar velocity surveys are usually sparse and noisy, which can lead to the aliasing of small-scale power into what is meant to be a probe of the largest scales. Previously, we developed an optimal `minimum variance' (MV) weighting scheme, designed to overcome this problem by minimizing the difference between the measured bulk flow (BF) and that which would be measured by an ideal survey. Here we extend this MV analysis to include the shear and octupole moments, which are designed to have almost no correlations between them so that they are virtually orthogonal. We apply this MV analysis to a compilation of all major peculiar velocity surveys, consisting of 4536 measurements. Our estimate of the BF on scales of ~100h-1Mpc has a magnitude of |v| = 416 +/- 78 kms -1 towards Galactic l = 282° +/- 11° and b = 6° +/- 6°. This result is in disagreement with Λ cold dark matter with Wilkinson Microwave Anisotropy Probe 5 (WMAP5) cosmological parameters at a high confidence level, but is in good agreement with our previous MV result without an orthogonality constraint, showing that the shear and octupole moments did not contaminate the previous BF measurement. The shear and octupole moments are consistent with WMAP5 power spectrum, although the measurement noise is larger for these moments than for the BF. The relatively low shear moments suggest that the sources responsible for the BF are at large distances.

  3. Discovery of deep and shallow trap states from step structures of rutile TiO{sub 2} vicinal surfaces by second harmonic and sum frequency generation spectroscopy

    SciTech Connect

    Takahashi, Hiroaki; Watanabe, Ryosuke; Miyauchi, Yoshihiro; Mizutani, Goro

    2011-04-21

    In this report, local electronic structures of steps and terraces on rutile TiO{sub 2} single crystal faces were studied by second harmonic and sum frequency generation (SHG/SFG) spectroscopy. We attained selective measurement of the local electronic states of the step bunches formed on the vicinal (17 18 1) and (15 13 0) surfaces using a recently developed step-selective probing technique. The electronic structures of the flat (110)-(1x1) (the terrace face of the vicinal surfaces) and (011)-(2x1) surfaces were also discussed. The SHG/SFG spectra showed that step structures are mainly responsible for the formation of trap states, since significant resonances from the trap states were observed only from the vicinal surfaces. We detected deep hole trap (DHT) states and shallow electron trap (SET) states selectively from the step bunches on the vicinal surfaces. Detailed analysis of the SHG/SFG spectra showed that the DHT and SET states are more likely to be induced at the top edges of the step bunches than on their hillsides. Unlike the SET states, the DHT states were observed only at the step bunches parallel to [1 1 1][equivalent to the step bunches formed on the (17 18 1) surface]. Photocatalytic activity for each TiO{sub 2} sample was also measured through methylene blue photodegradation reactions and was found to follow the sequence: (110) < (17 18 1) < (15 13 0) < (011), indicating that steps along [0 0 1] are more reactive than steps along [1 1 1]. This result implies that the presence of the DHT states observed from the step bunches parallel to [1 1 1] did not effectively contribute to the methylene blue photodegradation reactions.

  4. 34. mu. s isomer at high spin in sup 212 Fr: Evidence for a many-particle octupole coupled state

    SciTech Connect

    Byrne, A.P.; Dracoulis, G.D.; Schiffer, K.J.; Davidson, P.M.; Kibedi, T.; Fabricius, B.; Baxter, A.M.; Stuchbery, A.E. Australian National University, G.P.O. Box 4, Canberra, Australian Capital Territory )

    1990-07-01

    A very high spin isomeric state with {tau}{sub {ital m}}=34(3) {mu}s has been observed at an excitation energy of 8.5 MeV in {sup 212}Fr. The experimental evidence favors an {ital E}3 assignment, with a very large {ital E}3 transition strength, {ital B}({ital E}3)=100(12){times}10{sup 3} {ital e}{sup 2}fm{sup 6}, to one of the {gamma} rays de-exciting the isomer. The observed properties are in very good agreement with the characteristics of a 34{sup +} state predicted by the multiparticle octupole vibration model.

  5. Nanocarpets for Trapping Microscopic Particles

    NASA Technical Reports Server (NTRS)

    Noca, Flavio; Chen, Fei; Hunt, Brian; Bronikowski, Michael; Hoenk, Michael; Kowalczyk, Robert; Choi, Daniel

    2004-01-01

    Nanocarpets that is, carpets of carbon nanotubes are undergoing development as means of trapping microscopic particles for scientific analysis. Examples of such particles include inorganic particles, pollen, bacteria, and spores. Nanocarpets can be characterized as scaled-down versions of ordinary macroscopic floor carpets, which trap dust and other particulate matter, albeit not purposefully. Nanocarpets can also be characterized as mimicking both the structure and the particle-trapping behavior of ciliated lung epithelia, the carbon nanotubes being analogous to cilia. Carbon nanotubes can easily be chemically functionalized for selective trapping of specific particles of interest. One could, alternatively, use such other three-dimensionally-structured materials as aerogels and activated carbon for the purposeful trapping of microscopic particles. However, nanocarpets offer important advantages over these alternative materials: (1) Nanocarpets are amenable to nonintrusive probing by optical means; and (2) Nanocarpets offer greater surface-to-volume ratios.

  6. Parity splitting and E1/E2 branching in the alternating parity band of {sup 240}Pu from two-center octupole wave functions using supersymmetric quantum mechanics

    SciTech Connect

    Jolos, R. V.; Brentano, P. von

    2011-08-15

    An interpretation is suggested of the recently published experimental data on the alternating parity bands in {sup 240}Pu. The interpretation is based on the assumption that the main role in the description of the properties of the alternating parity bands plays the octupole mode which preserves the axial symmetry. The mathematical technique of the supersymmetric quantum mechanics is used for the realization of the model with the two-center octupole wave functions. A good description of the parity splitting and of the ratio of the dipole and quadrupole transitional moments is obtained for the first two bands.

  7. Halo ion trap mass spectrometer.

    PubMed

    Austin, Daniel E; Wang, Miao; Tolley, Samuel E; Maas, Jeffrey D; Hawkins, Aaron R; Rockwood, Alan L; Tolley, H Dennis; Lee, Edgar D; Lee, Milton L

    2007-04-01

    We describe a novel radio frequency ion trap mass analyzer based on toroidal trapping geometry and microfabrication technology. The device, called the halo ion trap, consists of two parallel ceramic plates, the facing surfaces of which are imprinted with sets of concentric ring electrodes. Radii of the imprinted rings range from 5 to 12 mm, and the spacing between the plates is 4 mm. Unlike conventional ion traps, in which hyperbolic metal electrodes establish equipotential boundary conditions, electric fields in the halo ion trap are established by applying different radio frequency potentials to each ring. The potential on each ring can be independently optimized to provide the best trapping field. The halo ion trap features an open structure, allowing easy access for in situ ionization. The toroidal geometry provides a large trapping and analyzing volume, increasing the number of ions that can be stored and reducing the effects of space-charge on mass analysis. Preliminary mass spectra show resolution (m/Deltam) of 60-75 when the trap is operated at 1.9 MHz and 500 Vp-p. PMID:17335180

  8. Cold atoms in videotape micro-traps

    NASA Astrophysics Data System (ADS)

    Sinclair, C. D. J.; Retter, J. A.; Curtis, E. A.; Hall, B. V.; Llorente Garcia, I.; Eriksson, S.; Sauer, B. E.; Hinds, E. A.

    2005-08-01

    We describe an array of microscopic atom traps formed by a pattern of magnetisation on a piece of videotape. We describe the way in which cold atoms are loaded into one of these micro-traps and how the trapped atom cloud is used to explore the properties of the trap. Evaporative cooling in the micro-trap down to a temperature of 1~μK allows us to probe the smoothness of the trapping potential and reveals some inhomogeneity produced by the magnetic film. We discuss future prospects for atom chips based on microscopic permanent-magnet structures.

  9. VACUUM TRAP

    DOEpatents

    Gordon, H.S.

    1959-09-15

    An improved adsorption vacuum trap for use in vacuum systems was designed. The distinguishing feature is the placement of a plurality of torsionally deformed metallic fins within a vacuum jacket extending from the walls to the central axis so that substantially all gas molecules pass through the jacket will impinge upon the fin surfaces. T fins are heated by direct metallic conduction, thereby ol taining a uniform temperature at the adeorbing surfaces so that essentially all of the condensible impurities from the evacuating gas are removed from the vacuum system.

  10. COLD TRAP

    DOEpatents

    Milleron, N.

    1963-03-12

    An improved linear-flow cold trap is designed for highvacuum applications such as mitigating back migration of diffusion pump oil moiecules. A central pot of liquid nitrogen is nested within and supported by a surrounding, vertical, helical coil of metai sheet, all enveloped by a larger, upright, cylindrical, vacuum vessel. The vertical interstices between successive turns of the coil afford lineal, axial, high-vacuum passages between open mouths at top and bottom of said vessel, while the coil, being cold by virtue of thermal contact of its innermost turn with the nitrogen pot, affords expansive proximate condensation surfaces. (AEC)

  11. Camera Traps on Wildlife Crossing Structures as a Tool in Gray Wolf (Canis lupus) Management - Five-Years Monitoring of Wolf Abundance Trends in Croatia.

    PubMed

    Šver, Lidija; Bielen, Ana; Križan, Josip; Gužvica, Goran

    2016-01-01

    The conservation of gray wolf (Canis lupus) and its coexistence with humans presents a challenge and requires continuous monitoring and management efforts. One of the non-invasive methods that produces high-quality wolf monitoring datasets is camera trapping. We present a novel monitoring approach where camera traps are positioned on wildlife crossing structures that channel the animals, thereby increasing trapping success and increasing the cost-efficiency of the method. In this way we have followed abundance trends of five wolf packs whose home ranges are intersected by a motorway which spans throughout the wolf distribution range in Croatia. During the five-year monitoring of six green bridges we have recorded 28 250 camera-events, 132 with wolves. Four viaducts were monitored for two years, recording 4914 camera-events, 185 with wolves. We have detected a negative abundance trend of the monitored Croatian wolf packs since 2011, especially severe in the northern part of the study area. Further, we have pinpointed the legal cull as probable major negative influence on the wolf pack abundance trends (linear regression, r2 > 0.75, P < 0.05). Using the same approach we did not find evidence for a negative impact of wolves on the prey populations, both wild ungulates and livestock. We encourage strict protection of wolf in Croatia until there is more data proving population stability. In conclusion, quantitative methods, such as the one presented here, should be used as much as possible when assessing wolf abundance trends. PMID:27327498

  12. Structure, bonding, and passivation of single carbon-related oxide hole traps near 4H-SiC/SiO2 interfaces

    NASA Astrophysics Data System (ADS)

    Ettisserry, D. P.; Goldsman, N.; Akturk, A.; Lelis, A. J.

    2014-11-01

    Single carbon interstitial in silicon dioxide, existing in carboxyl configuration, is shown to act as a border hole trap near 4H-SiC/SiO2 interface. Using density functional theory-based formation energy considerations, it is found to switch charge state between +2 and neutral as the 4H-SiC Fermi level sweeps its charge transition level located 1.4 eV above 4H-SiC valence band edge. Thus, carboxyl defect is predicted to be a potential candidate for threshold voltage instability in 4H-SiC MOSFETs. Post oxidation annealing of the interface with nitric oxide is shown to remove carboxyl defects. However, treating the defect in H2 creates a hole trap level at 1.1 eV above 4H-SiC valence band edge similar to the original carboxyl defect. The stability of carboxyl and H2 treated carboxyl defects in their doubly positive state is explained on the basis of their structural and bonding transformations during hole capture. These include puckering and back-bonding of silicon with lattice oxygen as in the well-known oxygen vacancy (E' center) hole traps and an increase in the bond order between carboxyl carbon and oxygen.

  13. Camera Traps on Wildlife Crossing Structures as a Tool in Gray Wolf (Canis lupus) Management - Five-Years Monitoring of Wolf Abundance Trends in Croatia

    PubMed Central

    Križan, Josip; Gužvica, Goran

    2016-01-01

    The conservation of gray wolf (Canis lupus) and its coexistence with humans presents a challenge and requires continuous monitoring and management efforts. One of the non-invasive methods that produces high-quality wolf monitoring datasets is camera trapping. We present a novel monitoring approach where camera traps are positioned on wildlife crossing structures that channel the animals, thereby increasing trapping success and increasing the cost-efficiency of the method. In this way we have followed abundance trends of five wolf packs whose home ranges are intersected by a motorway which spans throughout the wolf distribution range in Croatia. During the five-year monitoring of six green bridges we have recorded 28 250 camera-events, 132 with wolves. Four viaducts were monitored for two years, recording 4914 camera-events, 185 with wolves. We have detected a negative abundance trend of the monitored Croatian wolf packs since 2011, especially severe in the northern part of the study area. Further, we have pinpointed the legal cull as probable major negative influence on the wolf pack abundance trends (linear regression, r2 > 0.75, P < 0.05). Using the same approach we did not find evidence for a negative impact of wolves on the prey populations, both wild ungulates and livestock. We encourage strict protection of wolf in Croatia until there is more data proving population stability. In conclusion, quantitative methods, such as the one presented here, should be used as much as possible when assessing wolf abundance trends. PMID:27327498

  14. Computational analysis of triangular and honeycomb lattice-structured tapered nanoholes for enhanced light trapping in thin-film Si solar cells

    NASA Astrophysics Data System (ADS)

    Xavier, Jolly; Becker, Christiane

    2014-05-01

    For an optimized light harvesting while using diverse periodic photonic light-trapping architectures in low cost thin film crystalline silicon (c-Si) solar cells, it is also of prime importance to tune the features of their lattice point basis structure. In view of this, tapered nanoholes would be of importance for envisaged better light in-coupling due to graded index effect and also from the point of fabrication feasibility. Using a 3D finite element method based computational simulator, we investigate the basis structural influence of triangular as well as honeycomb lattice-structured experimentally feasible tapered air nanoholes in ~400 nm thick c-Si absorber on a glass substrate. We present a detailed convergence analysis of volume absorption in Si absorber with cylindrical as well as tapered nanoholes. For a wavelength rage of 300 nm to 1100 nm, we present the computed results on light absorption of the engineered Si nanoholes for a lattice periodicity of 600nm. In particular, we study the influence of tapering angle of engineered nano air holes in Si thin film for the absorption enhancement in photonic triangular and honeycomb lattice structured tapered nanoholes. Further we make a comparative analysis of cylindrical and tapered nanoholes for a range of light incident angles from 0° to 60°. For the presented triangular as well as honeycomb lattice structured nanoholes, we observe that in comparison to the cylindrical nanoholes, the tapered nanoholes perform better in terms of light trapping for enhanced light absorption in textured Si thin films even when the effective volume fraction of Si is lower in the absorber layer with tapered nanoholes in comparison to that of cylindrical ones. From the maximum achievable short circuit current density estimation in the present study, the performance of c-Si absorbing layer engineered with triangular lattice structured tapered air holes harvests light efficiently owing to its higher lattice symmetry among periodic

  15. Calculation of vibrational branching ratios and hyperfine structure of 24Mg19F and its suitability for laser cooling and magneto-optical trapping

    NASA Astrophysics Data System (ADS)

    Xu, Liang; Yin, Yanning; Wei, Bin; Xia, Yong; Yin, Jianping

    2016-01-01

    More recently, laser cooling of the diatomic radical magnesium monofluoride (24Mg19F ) is being experimentally preformed [Appl. Phys. Express 8, 092701 (2015), 10.7567/APEX.8.092701 and Opt. Express 22, 28645 (2014), 10.1364/OE.22.028645] and was also studied theoretically [Phys. Rev. A 91, 042511 (2015), 10.1103/PhysRevA.91.042511]. However, some important problems still remain unsolved, so, in our paper, we perform further theoretical study for the feasibility of laser cooling and trapping the 24Mg19F molecule. At first, the highly diagonal Franck-Condon factors of the main transitions are verified by the closed-form approximation, Morse approximation, and Rydberg-Klein-Rees inversion methods, respectively. Afterwards, we investigate the lower X 2Σ1/2 + hyperfine manifolds using a quantum effective Hamiltonian approach and obtain the zero-field hyperfine spectrum with an accuracy of less than 30 kHz ˜5 μ K compared with the experimental results, and then find out that one cooling beam and one or two repumping beams with their first-order sidebands are enough to implement an efficient laser slowing and cooling of 24Mg19F . Meanwhile, we also calculate the accurate hyperfine structure magnetic g factors of the rotational state (X 2Σ1/2 +,N =1 ) and briefly discuss the influence of the external fields on the hyperfine structure of 24Mg19F as well as its possibility of preparing three-dimensional magneto-optical trapping. Finally we give an explanation for the difference between the Stark and Zeeman effects from the perspective of parity and time reversal symmetry. Our study shows that, besides appropriate excitation wavelengths, the short lifetime for the first excited state A 2Π1 /2 , and lighter mass, the 24Mg19F radical could be a good candidate molecule amenable to laser cooling and magneto-optical trapping.

  16. Sorption induced structural deformation of sodium hexa-titanate nanofibers and their ability to selectively trap radioactive Ra(II) ions from water.

    PubMed

    Yang, Dongjiang; Zheng, Zhanfeng; Yuan, Yong; Liu, Hongwei; Waclawik, Eric R; Ke, Xuebin; Xie, Mengxia; Zhu, Huaiyong

    2010-02-14

    Sodium hexa-titanate (Na(2)Ti(6)O(13)) nanofibers, which have microporous tunnels, were prepared by heating sodium tri-titanate nanofibers with a layered structure at 573 K. The void section of the tunnels consist of eight linked TiO(6) octahedra, having a quasi-rectangular shape and the sodium ions located in these tunnel micropores are exchangeable. The exchange of these sodium ions with divalent cations, such as Sr(2+) and Ba(2+) ions, induces moderate structural deformation of the tunnels due to the stronger electrostatic interactions between di-valent ions Sr(2+) and Ba(2+) and the solid substrate. However, as the size of Ba(2+) ions (0.270 nm) is larger than the minimum width (0.240 nm) of the tunnel, the deformation can lock the Ba(2+) ions in the nanofibers, whereas Sr(2+) ions (0.224 nm) are smaller than the minimum width so the fibers can release the Sr(2+) ions exchanged into the channels instead. Therefore, the hexa-titanate (Na(2)Ti(6)O(13)) nanofibers display selectivity in trapping large divalent cations, since the deformed tunnels cannot trap smaller cations within the fibers. The fibers can be used to selectively remove radioactive Ra(2+) ions, which have a similar size and ion-exchange ability to Ba(2+) ions, from wastewater for safe disposal.

  17. First observation of excited states in {sup 137}Te and the extent of octupole instability in the lanthanides

    SciTech Connect

    Urban, W.; Korgul, A.; Rzaca-Urban, T.; Schulz, N.; Bentaleb, M.; Lubkiewicz, E.; Durell, J. L.; Leddy, M. J.; Jones, M. A.; Phillips, W. R.

    2000-04-01

    Excited states in {sup 137}Te, populated in spontaneous fission of {sup 248}Cm, were studied by means of prompt-{gamma} spectroscopy, using the EUROGAM2 multidetector array. This is the first observation of excited states in {sup 137}Te. The yrast excitations of {sup 137}Te are due to the three valence neutrons, occupying the {nu}f{sub 7/2} and {nu}h{sub 9/2} orbitals, similarly as observed in its heavier N=85 isotones. Systematic comparison of excited levels in the N=85 isotones shows inconsistencies in spin and parity assignments in {sup 139}Xe and {sup 141}Ba nuclei. The new data for {sup 137}Te do not confirm earlier suggestions that octupole correlations increase in the N=85 isotones, close to the Z=50 closed shell. (c) 2000 The American Physical Society.

  18. gamma-ray spectroscopic study of calcium-48,49 and scandium-50 focusing on low lying octupole vibration excitations

    NASA Astrophysics Data System (ADS)

    McPherson, David M.

    An inverse kinematic proton scattering experiment was performed at the National Superconducting Cyclotron Laboratory (NSCL) using the GRETINA-S800 detector system in conjunction with the Ursinus College liquid hydrogen target. gamma-ray yields from the experiment were determined using geant4 simulations, generating state population cross sections. These cross sections were used to extract the delta_3 deformation length for the low-lying octupole vibration excitations in Ca-48,49 using the coupled channels analysis code fresco. Particle-core coupling in Ca-49 was studied in comparison to Ca-48 through determination of the neutron and proton deformation lengths. The total inverse kinematic proton scattering deformation lengths were evaluated for the low-lying octupole vibration excitations in Ca-48,49 to be delta_3(Ca-48, 3. -_1) = 1.0(2)fm,delta_3(Ca-49, 9/2. +_1) = 1.2(1)fm, delta_3 (Ca-49, 9/2. +_1) = 1.5(2)fm, delta_3(Ca-49,5/2. +_1) = 1.1(1)fm. Proton and neutron deformation lengths for two of theseoctupole states were also determined to be delta_p(Ca-48, 3. -_1) = 0.9(1)fm,delta_p (Ca-49, 9/2. +_1) = 1.0(1)fm, delta_n(Ca-48, 3. -_1) = 1.1(3)fm, anddelta_n(Ca-49, 9/2. +_1) = 1.3(3)fm. Additionally, the ratios of the neutronto proton transition matrix elements were also determined for these two states to be M_n/M_p(Ca-48, 3. -_1) = 1.7(6) and M_n/M_p(Ca-49, 9/2. +_1) = 2.0(5).Statistically, the derived values for these two nuclei are nearly identical.

  19. Optimal design of light trapping in thin-film solar cells enhanced with graded SiNx and SiOxNy structure.

    PubMed

    Zhao, Yongxiang; Chen, Fei; Shen, Qiang; Zhang, Lianmeng

    2012-05-01

    In this paper, a graded SiNx and SiOxNy structure is proposed as antireflection coatings deposited on top of amorphous silicon (α-Si) thin-film solar cell. The structural parameters are optimized by differential evolution in order to enhance the optical absorption of solar cells to the greatest degree. The optimal design result demonstrates that the nonlinear profile of dielectric constant is superior to the linear profile, and discrete multilayer graded antireflection coatings can outperform near continuously graded antireflection coatings. What's more, the electric field intensity distributions clearly demonstrate the proposed graded SiNx and SiOxNy structure can remarkably increase the magnitude of electric field of a-Si:H layer and hence, enhance the light trapping of a-Si:H thin-film solar cells in the whole visible and near-infrared spectrum. Finally, we have compared the optical absorption enhancements of proposed graded SiNx and SiOxNy structure with nanoparticles structure, and demonstrated that it can result in higher enhancements compared to the dielectric SiC and TiO2 nanoparticles. We have shown that the optimal graded SiNx and SiOxNy structure optimized by differential evolution can reach 33.31% enhancement which has exceeded the ideal limit of 32% of nanoparticles structure including plasmonic Ag nanoparticles, dielectric SiC and TiO2 nanoparticles. PMID:22565735

  20. Optimal design of light trapping in thin-film solar cells enhanced with graded SiNx and SiOxNy structure.

    PubMed

    Zhao, Yongxiang; Chen, Fei; Shen, Qiang; Zhang, Lianmeng

    2012-05-01

    In this paper, a graded SiNx and SiOxNy structure is proposed as antireflection coatings deposited on top of amorphous silicon (α-Si) thin-film solar cell. The structural parameters are optimized by differential evolution in order to enhance the optical absorption of solar cells to the greatest degree. The optimal design result demonstrates that the nonlinear profile of dielectric constant is superior to the linear profile, and discrete multilayer graded antireflection coatings can outperform near continuously graded antireflection coatings. What's more, the electric field intensity distributions clearly demonstrate the proposed graded SiNx and SiOxNy structure can remarkably increase the magnitude of electric field of a-Si:H layer and hence, enhance the light trapping of a-Si:H thin-film solar cells in the whole visible and near-infrared spectrum. Finally, we have compared the optical absorption enhancements of proposed graded SiNx and SiOxNy structure with nanoparticles structure, and demonstrated that it can result in higher enhancements compared to the dielectric SiC and TiO2 nanoparticles. We have shown that the optimal graded SiNx and SiOxNy structure optimized by differential evolution can reach 33.31% enhancement which has exceeded the ideal limit of 32% of nanoparticles structure including plasmonic Ag nanoparticles, dielectric SiC and TiO2 nanoparticles.

  1. The structure and processes of the Siberian Traps sub-volcanic complex and consequences for end-Permian environmental crisis

    NASA Astrophysics Data System (ADS)

    Svensen, H.; Polozov, A. G.; Planke, S.

    2013-12-01

    The emplacement of the Siberian Traps Large igneous province is regarded as the key processes that initiated the end-Permian environmental crisis. The details of this link are however still under investigation. Among the suggestions are lava degassing of mantle- and crustal-derived gases, explosive lava and phreatomagmatic eruptions, and gas release from contact metamorphism related to the sub-volcanic sill complex. Whereas the lava pile is relatively well studied and investigated, the sub-volcanic sills, dikes, and contact aureoles are poorly studied and documented. We present borehole and field data of sills and contact aureoles from across the Siberian Traps, from Norilsk in the north to Bratsk in the south. The data have been compiled during three field campaigns in 2004, 2006, and 2010. The sill geometries and thicknesses varies considerably from kilometer-scale intrusive complexes to individual thin sills of a few tens of meters. In contrast to several other LIPs, sills are also emplaced within the extrusive pile. Thick sills (30-80 meters) occur in high abundance in the upper part of the sedimentary succession, affecting the coal-rich Tungusska Series sediments. Moreover, very thick sills (100-300 meters) are also emplaced within the vast Cambrian salt formations. We show that depending on the specific location within the province and the emplacement depth, the potential for degassing of both greenhouse gases (CH4, CO2), aerosols (SO2), and ozone destructive gases (CH3Cl, CH3Br) was in the 103 to 104 Gt range.

  2. Analysis of the fine structure of Sn11 +-Sn14 + ions by optical spectroscopy in an electron-beam ion trap

    NASA Astrophysics Data System (ADS)

    Windberger, A.; Torretti, F.; Borschevsky, A.; Ryabtsev, A.; Dobrodey, S.; Bekker, H.; Eliav, E.; Kaldor, U.; Ubachs, W.; Hoekstra, R.; Crespo López-Urrutia, J. R.; Versolato, O. O.

    2016-07-01

    We experimentally re-evaluate the fine structure of Sn11 +-Sn14 + ions. These ions are essential in bright extreme-ultraviolet (EUV) plasma-light sources for next-generation nanolithography, but their complex electronic structure is an open challenge for both theory and experiment. We combine optical spectroscopy of magnetic dipole M 1 transitions, in a wavelength range covering 260 to 780 nm, with charge-state selective ionization in an electron beam ion trap. Our measurements confirm the predictive power of ab initio calculations based on Fock space coupled cluster theory. We validate our line identification using semiempirical cowan calculations with adjustable wave-function parameters. Available Ritz combinations further strengthen our analysis. Comparison with previous work suggests that line identifications in the EUV need to be revisited.

  3. Phosphorous trapped within buckminsterfullerene

    NASA Astrophysics Data System (ADS)

    Larsson, J. A.; Greer, J. C.; Harneit, W.; Weidinger, A.

    2002-05-01

    Under normal circumstances, when covalent molecules form, electrons are exchanged between atoms to form bonds. However, experiment and theoretical computations reveal exactly the opposite effect for the formation of group V elements nitrogen and phosphorous encapsulated within a buckminsterfullerene molecule. The C60 carbon cage remains intact upon encapsulation of the atom, whereas the electronic charge cloud of the N or P atom contracts. We have studied the chemical, spin, and thermodynamic properties of endohedral phosphorous (P@C60) and have compared our results with earlier findings for N@C60. From a combined experimental and theoretical vantage, we are able to elucidate a model for the interaction between the trapped group V atom and the fullerene cage. A picture emerges for the electronic structure of these complexes, whereby an atom is trapped within a fullerene, and interacts weakly with the molecular orbitals of the C60 cage.

  4. A Mg2+-dependent RNA tertiary structure forms in the Bacillus subtilis trp operon leader transcript and appears to interfere with trpE translation control by inhibiting TRAP binding.

    PubMed

    Schaak, Janell E; Yakhnin, Helen; Bevilacqua, Philip C; Babitzke, Paul

    2003-09-19

    Expression of the trpEDCFBA operon of Bacillus subtilis is regulated by transcription attenuation and translation control mechanisms. In each case, binding of the trp RNA-binding attenuation protein (TRAP) to the untranslated trp leader transcript mediates conformational changes in the RNA secondary structure. We examined the structure of the trp leader readthrough RNA in the absence of TRAP. Using chemical and enzymatic probes, the secondary structure of the trp leader RNA was found to be similar to predicted models. In addition, this RNA was found to adopt a Mg(2+)-dependent, long-range tertiary interaction under physiological monovalent salt conditions. Formation of this tertiary structure does not require significant changes in the preformed secondary structure. Enzymatic probing of the RNA in the presence of competitor DNA oligonucleotides that were designed to disrupt the predicted tertiary structure allowed identification of the interacting partners as the single-stranded portion of the purine-rich TRAP binding target and a large downstream pyrimidine-rich internal loop. UV cross-linking experiments utilizing 5'-p-azidophenacyl-containing transcripts revealed a Mg(2+)-dependent cross-link. Mapping of this cross-link provided evidence that the single-stranded segment of the TRAP binding site is in close proximity to the internal loop. Results from UV melting experiments with wild-type and mutant trp leader transcripts suggested a likely base-pairing register for the tertiary structure. Filter-binding studies demonstrated that the addition of Mg(2+) inhibits TRAP binding, which may be partially due to the effect of Mg(2+) on RNA tertiary structure formation. Results from expression studies using trpE'-'lacZ translational fusions and RNA-directed cell-free translation experiments suggest that the Mg(2+)-dependent tertiary structure inhibits TRAP's ability to regulate translation of trpE. PMID:12963367

  5. Characterization of Si-SiO2 interface traps in p-metal-oxide-semiconductor structures with thin oxides by conductance technique

    NASA Astrophysics Data System (ADS)

    Hung, K. K.; Cheng, Y. C.

    1987-11-01

    There has been a substantial effort made on the application of Nicollian-Goetzberger's conductance technique to probe the Si-SiO2 interface traps on n-type substrates. However, it was reported that conductance measurement on the p-type substrate was impossible due to the strong surface potential fluctuations. By using metal-oxide-semiconductor (MOS) capacitors with thin (88-434 Å) oxides to damp out the fluctuations arising from the interface charge inhomogeneities, it is possible to carry out an accurate conductance measurement on as-oxidized p-MOS capacitors. A systematic dependence of the interface trap density on the oxide thickness and oxidation temperature is observed. The hole capture cross sections have no obvious dependence on the process conditions, but show an exponential dependence on the energy. Both the magnitude and bias dependence of the measured time-constant dispersion parameters are found to be much larger than those theoretically predicted. Results of numerical simulation show that the anomalous width of the conductance peaks observed for p-MOS structures is caused by the strong energy dependence of the hole capture cross sections, which has been overlooked in the conventional theory of MOS conductance.

  6. Mini ion trap mass spectrometer

    DOEpatents

    Dietrich, D.D.; Keville, R.F.

    1995-09-19

    An ion trap is described which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10{sup 9} and commercial mass spectrometers requiring 10{sup 4} ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products. 10 figs.

  7. Acoustic trapping of active matter.

    PubMed

    Takatori, Sho C; De Dier, Raf; Vermant, Jan; Brady, John F

    2016-01-01

    Confinement of living microorganisms and self-propelled particles by an external trap provides a means of analysing the motion and behaviour of active systems. Developing a tweezer with a trapping radius large compared with the swimmers' size and run length has been an experimental challenge, as standard optical traps are too weak. Here we report the novel use of an acoustic tweezer to confine self-propelled particles in two dimensions over distances large compared with the swimmers' run length. We develop a near-harmonic trap to demonstrate the crossover from weak confinement, where the probability density is Boltzmann-like, to strong confinement, where the density is peaked along the perimeter. At high concentrations the swimmers crystallize into a close-packed structure, which subsequently 'explodes' as a travelling wave when the tweezer is turned off. The swimmers' confined motion provides a measurement of the swim pressure, a unique mechanical pressure exerted by self-propelled bodies. PMID:26961816

  8. Trapping Protoplanets at the Snowlines.

    NASA Astrophysics Data System (ADS)

    Baillié, K.; Charnoz, S.; Pantin, E.

    2015-12-01

    We follow the viscous evolution of protoplanetary disks by modeling self-consistently their dynamics, thermodynamics, photosphere geometry and composition (Baillié & Charnoz., 2014, ApJ and Baillié et al., 2015, A&A). Our hydrodynamical numerical code allows us to estimate the local gradients in temperature and density that drive the type I migration of planetary embryos. In particular, we identify irregular structures in the disk: shadowed regions that are not directly irradiated by the star, temperature plateaux at the sublimation temperature of the main dust components of the disk. These icelines appear to be related with planetary traps. Though planetary embryos can be trapped temporarily in some early transient traps, the other traps (more permanent) will allow protoplanets to survive and favor their growth by collisions between embryos at some specific orbits.

  9. Mini ion trap mass spectrometer

    DOEpatents

    Dietrich, Daniel D.; Keville, Robert F.

    1995-01-01

    An ion trap which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10.sup.9 and commercial mass spectrometers requiring 10.sup.4 ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products.

  10. Structural Distinction of Diacyl-, Alkylacyl, and Alk-1-Enylacyl Glycerophosphocholines as [M - 15]- Ions by Multiple-Stage Linear Ion-Trap Mass Spectrometry with Electrospray Ionization

    NASA Astrophysics Data System (ADS)

    Hsu, Fong-Fu; Lodhi, Irfan J.; Turk, John; Semenkovich, Clay F.

    2014-08-01

    We describe a linear ion-trap (LIT) multiple-stage (MSn) mass spectrometric approach towards differentiation of alkylacyl, alk-1-enylacyl- and diacyl-glycerophoscholines (PCs) as the [M - 15]- ions desorbed by electrospray ionization (ESI) in the negative-ion mode. The MS4 mass spectra of the [M - 15 - R2'CH = CO]- ions originated from the three PC subfamilies are readily distinguishable, resulting in unambiguous distinction of the lipid classes. This method is applied to two alkyl ether rich PC mixtures isolated from murine bone marrow neutrophils and kidney, respectively, to explore its utility in the characterization of complex PC mixture of biological origin, resulting in the realization of the detailed structures of the PC species, including various classes and many minor isobaric isomers.

  11. Structural elucidation of biologically active neomycin N-octyl derivatives in a regioisomeric mixture by means of liquid chromatography/ion trap time-of-flight mass spectrometry.

    PubMed

    Giera, Martin; de Vlieger, Jon S B; Lingeman, Henk; Irth, Hubertus; Niessen, Wilfried M A

    2010-05-30

    Structural elucidation of six regioisomers of mono-N-octyl derivatized neomycin is achieved using MS(n) (up to n = 4) on an ion trap time-of-flight (IT-TOF) instrument equipped with electrospray ionization. The mixture of six derivatized neomycin analogues was generated by reductive amination in a shotgun synthetic approach. In parallel to the liquid chromatography/mass spectrometry (LC/MS) detection, the antibacterial activity of the neomycin regioisomers was tested by post-column addition of buffer and bacterial inocula, subsequent microfractionation of the resulting mixture, incubation, and finally a chemiluminescence-based bioactivity measurement based on the production of bacterial ATP. The MS-based high-resolution screening approach described can be applied in medicinal chemistry to help in designing and producing new antibiotic substances, which is particularly challenging due to the high functionality of most antibiotic substances, therefore requiring advanced (hyphenated) separation and detection techniques for compound mixtures.

  12. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Structural Feature and Solute Trapping of Rapidly Grown Ni3Sn Intermetallic Compound

    NASA Astrophysics Data System (ADS)

    Qin, Hai-Yan; Wang, Wei-Li; Wei, Bing-Bo

    2009-11-01

    The rapid dendritic growth of primary Ni3Sn phase in undercooled Ni-30.9%Sn-5%Ge alloy is investigated by using the glass fluxing technique. The dendritic growth velocity of Ni3Sn compound is measured as a function of undercooling, and a velocity of 2.47 m/s is achieved at the maximum undercooling of 251 K (0.17TL). The addition of the Ge element reduces its growth velocity as compared with the binary Ni75Sn25 alloy. During rapid solidification, the Ni3Sn compound behaves like a normal solid solution and it displays a morphological transition of “coarse dendrite-equiaxed grain-vermicular structure" with the increase of undercooling. Significant solute trapping of Ge atoms occurs in the whole undercooling range.

  13. Scalable Designs for Planar Ion Trap Arrays

    NASA Astrophysics Data System (ADS)

    Slusher, R. E.

    2007-03-01

    Recent progress in quantum operations with trapped ion qubits has been spectacular for qubit counts up to approximately ten ions. Two qubit quantum gates, quantum error correction, simple quantum algorithms and entanglement of up to 8 qubits have been demonstrated by groups including those at NIST, University of Michigan, University of Innsbruck and Oxford. Interesting problems in quantum information processing including quantum simulations of condensed matter systems and quantum repeaters for long distance quantum communication systems require hundreds or thousands of qubits. Initial designs for an ion trap ``Quantum CCD'' using spatially multiplexed planar ion traps as well as initial experiments using planar ion traps are promising routes to scaling up the number of trapped ions to more interesting levels. We describe designs for planar ion traps fabricated using silicon VLSI techniques. This approach allows the control voltages required for the moving and positioning the ions in the array to be connected vertically through the silicon substrate to underlying CMOS electronics. We have developed techniques that allow the ion trap structures to be fabricated monolithically on top of the CMOS electronics. The planar traps have much weaker trapping depths than the more conventional multi-level traps. However, the trap depths are still adequate for trapping hot ions from many ion sources. The planar traps also involve more complex configurations for laser cooling and micromotion control. Initial solutions to these problems will be presented. Laser access to the ions can be provided by laser beams grazing the trap surface or by using vertical slots through the trap chip. We will also discuss limits imposed by power dissipation and ion transport through trap junctions (e.g. crosses and Ys). We have fabricated these VLSI based traps in a number of configurations. Initial fabrication and packaging challenges will be discussed. D. Kielpinski, C. Monroe, and D.J. Wineland

  14. First hyperpolarizabilities of 1,3,5-tricyanobenzene derivatives: origin of larger beta values for the octupoles than for the dipoles.

    PubMed

    Lee, Sang Hae; Park, Jo Ryoung; Jeong, Mi-Yun; Kim, Hwan Myung; Li, Shaojun; Song, Jongwon; Ham, Sihyun; Jeon, Seung-Joon; Cho, Bong Rae

    2006-01-16

    A series of donor-acceptor substituted stilbene and diphenylacetylene derivatives and their octupolar analogues have been synthesized and the linear and nonlinear optical properties (beta) studied by both experiments and theoretical calculation. The lambda(max) of the dipoles increases with the conjugation length and is always larger when the C=C bond is used, instead of the C[triple bond]C bond, as the conjugation bridge. Although the lambda(max) values of the octupoles show no clear trend, they are much larger than those of the dipoles. The beta(0) values of the dipoles increase with conjugation length and as the conjugation bridge is changed from the C[triple bond]C to C=C bond. This increase is accompanied by an increase in either lambda(max) or the oscillator strength. Similarly, the beta(0) values of the octupoles increase with the conjugation length and with a change in the donor in the order: NEt2 < N(i-amyl)Ph < NPh2. Moreover, beta(yyy)/beta(zzz) ratios are in the range of 1.6-3.9 and decrease with the conjugation length. Beta values calculated by the finite-field and sum-over-states methods are in good agreement with the experimental data. Also, there is a parallel relationship between the calculated beta values and bond length alternation (BLA). From these results, the origin of the larger beta values for octupoles than for dipoles is assessed. PMID:16323225

  15. Three-Rod Linear Ion Traps

    NASA Technical Reports Server (NTRS)

    Janik, Gary R.; Prestage, John D.; Maleki, Lutfollah

    1993-01-01

    Three-parallel-rod electrode structures proposed for use in linear ion traps and possibly for electrostatic levitation of macroscopic particles. Provides wider viewing angle because they confine ions in regions outside rod-electrode structures.

  16. Trapping polar molecules in an ac trap

    SciTech Connect

    Bethlem, Hendrick L.; Veldhoven, Jacqueline van; Schnell, Melanie; Meijer, Gerard

    2006-12-15

    Polar molecules in high-field seeking states cannot be trapped in static traps as Maxwell's equations do not allow a maximum of the electric field in free space. It is possible to generate an electric field that has a saddle point by superposing an inhomogeneous electric field to an homogeneous electric field. In such a field, molecules are focused along one direction, while being defocused along the other. By reversing the direction of the inhomogeneous electric field the focusing and defocusing directions are reversed. When the fields are being switched back and forth at the appropriate rate, this leads to a net focusing force in all directions. We describe possible electrode geometries for creating the desired fields and discuss their merits. Trapping of {sup 15}ND{sub 3} ammonia molecules in a cylindrically symmetric ac trap is demonstrated. We present measurements of the spatial distribution of the trapped cloud as a function of the settings of the trap and compare these to both a simple model assuming a linear force and to full three-dimensional simulations of the experiment. With the optimal settings, molecules within a phase-space volume of 270 mm{sup 3} (m/s){sup 3} remain trapped. This corresponds to a trap depth of about 5 mK and a trap volume of about 20 mm{sup 3}.

  17. Crystal structure of CobK reveals strand-swapping between Rossmann-fold domains and molecular basis of the reduced precorrin product trap

    PubMed Central

    Gu, Shuang; Sushko, Oleksandr; Deery, Evelyne; Warren, Martin J.; Pickersgill, Richard W.

    2015-01-01

    CobK catalyzes the essential reduction of the precorrin ring in the cobalamin biosynthetic pathway. The crystal structure of CobK reveals that the enzyme, despite not having the signature sequence, comprises two Rossmann fold domains which bind coenzyme and substrate respectively. The two parallel β-sheets have swapped their last β-strands giving a novel sheet topology which is an interesting variation on the Rossmann-fold. The trapped ternary complex with coenzyme and product reveals five conserved basic residues that bind the carboxylates of the tetrapyrrole tightly anchoring the product. A loop, disordered in both the apoenzyme and holoenzyme structures, closes around the product further tightening binding. The structure is consistent with a mechanism involving protonation of C18 and pro-R hydride transfer from NADPH to C19 of precorrin-6A and reveals the interactions responsible for the specificity of CobK. The almost complete burial of the reduced precorrin product suggests a remarkable form of metabolite channeling where the next enzyme in the biosynthetic pathway triggers product release. PMID:26616290

  18. Crystal structure of CobK reveals strand-swapping between Rossmann-fold domains and molecular basis of the reduced precorrin product trap

    NASA Astrophysics Data System (ADS)

    Gu, Shuang; Sushko, Oleksandr; Deery, Evelyne; Warren, Martin J.; Pickersgill, Richard W.

    2015-11-01

    CobK catalyzes the essential reduction of the precorrin ring in the cobalamin biosynthetic pathway. The crystal structure of CobK reveals that the enzyme, despite not having the signature sequence, comprises two Rossmann fold domains which bind coenzyme and substrate respectively. The two parallel β-sheets have swapped their last β-strands giving a novel sheet topology which is an interesting variation on the Rossmann-fold. The trapped ternary complex with coenzyme and product reveals five conserved basic residues that bind the carboxylates of the tetrapyrrole tightly anchoring the product. A loop, disordered in both the apoenzyme and holoenzyme structures, closes around the product further tightening binding. The structure is consistent with a mechanism involving protonation of C18 and pro-R hydride transfer from NADPH to C19 of precorrin-6A and reveals the interactions responsible for the specificity of CobK. The almost complete burial of the reduced precorrin product suggests a remarkable form of metabolite channeling where the next enzyme in the biosynthetic pathway triggers product release.

  19. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Low-Energy Collective Excitation of Bose-Einstein Condensates in an Anisotropic Magnetic Trap

    NASA Astrophysics Data System (ADS)

    Yang, Lu; Wang, Xiao-Rui; Li, Ke; Tan, Xin-Zhou; Xiong, Hong-Wei; Lu, Bao-Long

    2009-07-01

    We experimentally investigate the collective excitation of 87Rb Bose-Einstein condensates confined in a cigar-shaped magnetic trap (QUIC trap). Using a method of magnetic perturbation, the center-of-mass oscillation of the condensate is excited, so that the radial trapping frequency of the QUIC trap can be precisely determined. A high-order excitation, characterized by a fast shape oscillation, also occurs simultaneously, with a noticeable damping in the oscillation amplitude compared with the oscillation of the center of mass. The measured oscillation frequencies, associated with these two low-energy excitation modes, agree well with theoretical predictions based on the Gross-Pitaevskii equation.

  20. Trap States in Al2O3 InAlN/GaN Metal-Oxide-Semiconductor Structures by Frequency-Dependent Conductance Analysis

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Zhao, Sheng-Lei; Xue, Jun-Shuai; Zhang, Kai; Ma, Xiao-Hua; Zhang, Jin-Cheng; Hao, Yue

    2014-03-01

    We present a detailed analysis of the trap states in atomic layer deposition Al2O3/InAlN/GaN high electron mobility transistors grown by pulsed metal organic chemical vapor deposition. Trap densities, trap energies and time constants are determined by frequency-dependent conductance measurements. A high trap density of up to 1.6 × 1014 cm-2eV-1 is observed, which may be due to the lack of the cap layer causing the vulnerability to the subsequent high temperature annealing process.

  1. High-Resolution Crystal Structures of Streptococcus pneumoniae Nicotinamidase with Trapped Intermediates Provide Insights into the Catalytic Mechanism and Inhibition by Aldehydes

    SciTech Connect

    French, Jarrod B.; Cen, Yana; Sauve, Anthony A.; Ealick, Steven E.

    2010-11-11

    Nicotinamidases are salvage enzymes that convert nicotinamide to nicotinic acid. These enzymes are essential for the recycling of nicotinamide into NAD{sup +} in most prokaryotes and most single-cell and multicellular eukaryotes, but not in mammals. The significance of these enzymes for nicotinamide salvage and for NAD{sup +} homeostasis has stimulated interest in nicotinamidases as possible antibiotic targets. Nicotinamidases are also regulators of intracellular nicotinamide concentrations, thereby regulating signaling of downstream NAD{sup +}-consuming enzymes, such as the NAD{sup +}-dependent deacetylases (sirtuins). Here, we report several high-resolution crystal structures of the nicotinamidase from Streptococcus pneumoniae (SpNic) in unliganded and ligand-bound forms. The structure of the C136S mutant in complex with nicotinamide provides details about substrate binding, while a trapped nicotinoyl thioester in a complex with SpNic reveals the structure of the proposed thioester reaction intermediate. Examination of the active site of SpNic reveals several important features, including a metal ion that coordinates the substrate and the catalytically relevant water molecule and an oxyanion hole that both orients the substrate and offsets the negative charge that builds up during catalysis. Structures of this enzyme with bound nicotinaldehyde inhibitors elucidate the mechanism of inhibition and provide further details about the catalytic mechanism. In addition, we provide a biochemical analysis of the identity and role of the metal ion that orients the ligand in the active site and activates the water molecule responsible for hydrolysis of the substrate. These data provide structural evidence of several proposed reaction intermediates and allow for a more complete understanding of the catalytic mechanism of this enzyme.

  2. High Resolution Crystal Structures of Streptococcus pneumoniae Nicotinamidase with Trapped Intermediates Provide Insights into Catalytic Mechanism and Inhibition by Aldehydes∥,‡

    PubMed Central

    French, Jarrod B.; Cen, Yana; Sauve, Anthony A.; Ealick, Steven E.

    2010-01-01

    Nicotinamidases are salvage enzymes that convert nicotinamide to nicotinic acid. These enzymes are essential for the recycling of nicotinamide into NAD+ in most prokaryotes, most single cell and multicellular eukaryotes, but not in mammals. The significance of these enzymes for nicotinamide salvage and for NAD+ homeostasis has increased interest in nicotinamidases as possible antibiotic targets. Nicotinamidases are also regulators of intracellular nicotinamide concentrations, thereby regulating signaling of downstream NAD+ consuming enzymes, such as the NAD+-dependent deacetylases (sirtuins). Here, we report several high resolution crystal structures of the nicotinamidase from Streptococcus pneumoniae (SpNic) in unliganded and ligand-bound forms. The structure of the C136S mutant in complex with nicotinamide provides details about substrate binding while a trapped nicotinoyl-thioester complexed with SpNic reveals the structure of the proposed thioester reaction intermediate. Examination of the active site of SpNic reveals several important features including a metal ion that coordinates the substrate and the catalytically relevant water molecule, and an oxyanion hole which both orients the substrate and offsets the negative charge that builds up during catalysis. Structures of this enzyme with bound nicotinaldehyde inhibitors elucidate the mechanism of inhibition and provide further details about the catalytic mechanism. In addition, we provide a biochemical analysis of the identity and role of the metal ion that orients the ligand in the active site and activates the water molecule responsible for hydrolysis of the substrate. These data provide structural evidence for several proposed reaction intermediates and allow for a more complete understanding of the catalytic mechanism of this enzyme. PMID:20853856

  3. Structural analysis of poly[(R,S)-3-hydroxybutyrate-co-L-lactide] copolyesters by electrospray ionization ion trap mass spectrometry.

    PubMed

    Adamus, Grazyna

    2007-01-01

    Two random copolyesters of poly[(R,S)-3-hydroxybutyrate-co-L-lactide] (P[(R,S)-3HB-co-LA]), prepared by equimolar reaction of (R,S)-beta-butyrolactone with L-lactic acid and (R,S)-3-hydroxybutyric acid with L-lactide, respectively, were characterized by electrospray ionization ion trap mass spectrometry (ESI-ITMS). Detailed studies of these copolyesters were performed by means of collision-induced dissociation (CID). The molecular architecture of individual copolyester macromolecules, including chemical structures of their end groups (hydroxyl and carboxylate), were established on the basis of their ESI mass spectra. The influence of an intermolecular transesterification reaction on the microstructure of the copolyester synthesized by equimolar reaction of (R,S)-3-hydroxybutyric acid with L-lactide was observed. The mass spectra provided information on sequence distribution and indicated that, despite the synthetic pathway applied, random P[(R,S)-3HB-co-LA] copolyesters were formed predominantly. The arrangements of comonomer structural units along the copolyester chains were evaluated by the respective ESI-MS/MS fragmentation pathways. PMID:17610241

  4. Structural Basis for Small G Protein Effector Interaction of Ras-related Protein 1 (Rap1) and Adaptor Protein Krev Interaction Trapped 1 (KRIT1)

    SciTech Connect

    Li, Xiaofeng; Zhang, Rong; Draheim, Kyle M.; Liu, Weizhi; Calderwood, David A.; Boggon, Titus J.

    2012-09-17

    Cerebral cavernous malformations (CCMs) affect 0.1-0.5% of the population resulting in leaky vasculature and severe neurological defects. KRIT1 (Krev interaction trapped-1) mutations associate with {approx}40% of familial CCMs. KRIT1 is an effector of Ras-related protein 1 (Rap1) GTPase. Rap1 relocalizes KRIT1 from microtubules to cell membranes to impact integrin activation, potentially important for CCM pathology. We report the 1.95 {angstrom} co-crystal structure of KRIT1 FERM domain in complex with Rap1. Rap1-KRIT1 interaction encompasses an extended surface, including Rap1 Switch I and II and KRIT1 FERM F1 and F2 lobes. Rap1 binds KRIT1-F1 lobe using a GTPase-ubiquitin-like fold interaction but binds KRIT1-F2 lobe by a novel interaction. Point mutagenesis confirms the interaction. High similarity between KRIT1-F2/F3 and talin is revealed. Additionally, the mechanism for FERM domains acting as GTPase effectors is suggested. Finally, structure-based alignment of each lobe suggests classification of FERM domains as ERM-like and TMFK-like (talin-myosin-FAK-KRIT-like) and that FERM lobes resemble domain 'modules.'

  5. Local trap spectroscopy in superconducting tunnel junctions

    SciTech Connect

    Kozorezov, A. G.; Wigmore, J. K.; Peacock, A.; Poelaert, A.; Verhoeve, P.; den Hartog, R.; Brammertz, G.

    2001-06-04

    We show that thermal activation of quasiparticles from local traps is responsible for the temperature variation of responsivity observed for some superconducting tunneling junction photon detectors. With this model, the depth of the local traps in two different proximized Ta structures was found to be the same, 0.20{+-}0.02 meV. {copyright} 2001 American Institute of Physics.

  6. Bloodmeal host congregation and landscape structure impact the estimation of female mosquito (Diptera: Culicidae) abundance using dry ice-baited traps.

    PubMed

    Thiemann, Tara; Nelms, Brittany; Reisen, William K

    2011-05-01

    Vegetation patterns and the presence of large numbers of nesting herons and egrets significantly altered the number of host-seeking Culex tarsalis Coquillett (Diptera: Culicidae) collected at dry ice-baited traps. The numbers of females collected per trap night at traps along the ecotone of Eucalyptus stands with and without a heron colony were always greater or equal to numbers collected at traps within or under canopy. No Cx. tarsalis were collected within or under Eucaplytus canopy during the peak heron nesting season, even though these birds frequently were infected with West Nile virus and large number of engorged females could be collected at resting boxes. These data indicate a diversion of host-seeking females from traps to nesting birds reducing sampling efficiency.

  7. Bloodmeal Host Congregation and Landscape Structure Impact the Estimation of Female Mosquito (Diptera: Culicidae) Abundance Using Dry Ice-Baited Traps

    PubMed Central

    THIEMANN, TARA; NELMS, BRITTANY; REISEN, WILLIAM K.

    2011-01-01

    Vegetation patterns and the presence of large numbers of nesting herons and egrets significantly altered the number of host-seeking Culex tarsalis Coquillett (Diptera: Culicidae) collected at dry ice-baited traps. The numbers of females collected per trap night at traps along the ecotone of Eucalyptus stands with and without a heron colony were always greater or equal to numbers collected at traps within or under canopy. No Cx. tarsalis were collected within or under Eucaplytus canopy during the peak heron nesting season, even though these birds frequently were infected with West Nile virus and large number of engorged females could be collected at resting boxes. These data indicate a diversion of host-seeking females from traps to nesting birds reducing sampling efficiency. PMID:21661310

  8. Crystal structure of release factor RF3 trapped in the GTP state on a rotated conformation of the ribosome

    SciTech Connect

    Zhou, Jie; Lancaster, Laura; Trakhanov, Sergei; Noller, Harry F.

    2012-03-26

    The class II release factor RF3 is a GTPase related to elongation factor EF-G, which catalyzes release of class I release factors RF1 and RF2 from the ribosome after termination of protein synthesis. The 3.3 {angstrom} crystal structure of the RF3 {center_dot} GDPNP {center_dot} ribosome complex provides a high-resolution description of interactions and structural rearrangements that occur when binding of this translational GTPase induces large-scale rotational movements in the ribosome. RF3 induces a 7{sup o} rotation of the body and 14{sup o} rotation of the head of the 30S ribosomal subunit, and itself undergoes inter- and intradomain conformational rearrangements. We suggest that ordering of critical elements of switch loop I and the P loop, which help to form the GTPase catalytic site, are caused by interactions between the G domain of RF3 and the sarcin-ricin loop of 23S rRNA. The rotational movements in the ribosome induced by RF3, and its distinctly different binding orientation to the sarcin-ricin loop of 23S rRNA, raise interesting implications for the mechanism of action of EF-G in translocation.

  9. Sorption vacuum trap

    NASA Technical Reports Server (NTRS)

    Barrington, A. E.; Caruso, A. J.

    1970-01-01

    Modified sorption trap for use in high vacuum systems contains provisions for online regeneration of sorbent material. Trap is so constructed that it has a number of encapsulated resistance heaters and a valving and pumping device for removing gases from heated sorbing material. Excessive downtime is eliminated with this trap.

  10. Structural basis for the antipolymer activity of Hb ζ2βs2 trapped in a tense conformation

    NASA Astrophysics Data System (ADS)

    Safo, Martin K.; Ko, Tzu-Ping; Schreiter, Eric R.; Eric Russell, J.

    2015-11-01

    The phenotypical severity of sickle cell disease (SCD) can be mitigated by modifying mutant hemoglobin S (Hb s, Hb α2β 2s) to contain embryonic ζ globin in place of adult α-globin subunits (Hb ζ2β2s). Crystallographical analyses of liganded Hb ζζ2β2s, though, demonstrate a tense (T-state) quaternary structure that paradoxically predicts its participation in--rather than its exclusion from--pathological deoxyHb S polymers. We resolved this structure-function conundrum by examining the effects of α → ζ exchange on the characteristics of specific amino acids that mediate sickle polymer assembly. Superposition analyses of the βs subunits of T-state deoxyHb α2β2s and T-state CO-liganded Hb ζ2β2s reveal significant displacements of both mutant βsVal6 and conserved β-chain contact residues, predicting weakening of corresponding polymer-stabilizing interactions. Similar comparisons of the α- and ζ-globin subunits implicate four amino acids that are either repositioned or undergo non-conservative substitution, abrogating critical polymer contacts. CO-Hb ζ2βs2 additionally exhibits a unique trimer-of-heterotetramers crystal packing that is sustained by novel intermolecular interactions involving the pathological βsVal6, contrasting sharply with the classical double-stranded packing of deoxyHb S. Finally, the unusually large buried solvent-accessible surface area for CO-Hb ζ2β2s suggests that it does not co-assemble with deoxyHb S in vivo. In sum, the antipolymer activities of Hb ζ203b2;2s appear to arise from both repositioning and replacement of specific α- and βs-chain residues, favoring an alternate T-state solution structure that is excluded from pathological deoxyHb S polymers. These data account for the antipolymer activity of Hb ζ2β2s, and recommend the utility of SCD therapeutics that capitalize on α-globin exchange strategies.

  11. Structure of the HIV-1 Full-Length Capsid Protein in a Conformationally Trapped Unassembled State Induced by Small-Molecule Binding

    SciTech Connect

    Du, Shoucheng; Betts, Laurie; Yang, Ruifeng; Shi, Haibin; Concel, Jason; Ahn, Jinwoo; Aiken, Christopher; Zhang, Peijun; Yeh, Joanne I.

    2012-11-26

    The capsid (CA) protein plays crucial roles in HIV infection and replication, essential to viral maturation. The absence of high-resolution structural data on unassembled CA hinders the development of antivirals effective in inhibiting assembly. Unlike enzymes that have targetable, functional substrate-binding sites, the CA does not have a known site that affects catalytic or other innate activity, which can be more readily targeted in drug development efforts. We report the crystal structure of the HIV-1 CA, revealing the domain organization in the context of the wild-type full-length (FL) unassembled CA. The FL CA adopts an antiparallel dimer configuration, exhibiting a domain organization sterically incompatible with capsid assembly. A small compound, generated in situ during crystallization, is bound tightly at a hinge site ('H site'), indicating that binding at this interdomain region stabilizes the ADP conformation. Electron microscopy studies on nascent crystals reveal both dimeric and hexameric lattices coexisting within a single condition, in agreement with the interconvertibility of oligomeric forms and supporting the feasibility of promoting assembly-incompetent dimeric states. Solution characterization in the presence of the H-site ligand shows predominantly unassembled dimeric CA, even under conditions that promote assembly. Our structure elucidation of the HIV-1 FL CA and characterization of a potential allosteric binding site provides three-dimensional views of an assembly-defective conformation, a state targeted in, and thus directly relevant to, inhibitor development. Based on our findings, we propose an unprecedented means of preventing CA assembly, by 'conformationally trapping' CA in assembly-incompetent conformational states induced by H-site binding.

  12. Transition metals as electron traps. I. Structures, energetics, electron capture, and electron-transfer-induced dissociations of ternary copper-peptide complexes in the gas phase.

    PubMed

    Turecek, Frantisek; Jones, Jace W; Holm, Anne I S; Panja, Subhasis; Nielsen, Steen Brøndsted; Hvelplund, Preben

    2009-05-01

    Electron-induced dissociations of gas-phase ternary copper-2,2'-bipyridine complexes of Gly-Gly-Gly and Gly-Gly-Leu were studied on a time scale ranging from 130 ns to several milliseconds using a combination of charge-reversal ((+)CR(-)) and electron-capture-induced dissociation (ECID) measured on a beam instrument and electron capture dissociation (ECD) measured in a Penning trap. Charge-reduced intermediates were observed on the short time scale in the (+)CR(-) and ECID experiments but not in ECD. Ion dissociations following electron transfer or capture mostly occurred by competitive bpy or peptide ligand loss, whereas peptide backbone fragmentations were suppressed in the presence of the ligated metal ion. Extensive electron structure theory calculations using density functional theory and large basis sets provided optimized structures and energies for the precursor ions, charge-reduced intermediates, and dissociation products. The Cu complexes underwent substantial structure changes upon electron capture. Cu was calculated to be pentacoordinated in the most stable singly charged complexes of the [Cu(peptide-H)bpy](+*) type where it carried a approximately +1 atomic charge. Cu coordination in charge-reduced [Cu(peptide-H)bpy] intermediates depended on the spin state. The themodynamically more stable singlet states had tricoordinated Cu, whereas triplet states had a tetracoordinated Cu. Cu was tricoordinated in stable [Cu(peptide-H)bpy](-*) products of electron transfer. [Cu(peptide)bpy](2+*) complexes contained the peptide ligand in a zwitterionic form while Cu was tetracoordinated. Upon electron capture, Cu was tri- or tetracoordinated in the [Cu(peptide)bpy](+) charge-reduced analogs and the peptide ligands underwent prototropic isomerization to canonical forms. The role of excited singlet and triplet electronic states is assessed. PMID:19132713

  13. Superamphiphobic, light-trapping FeSe2 particles with a micro-nano hierarchical structure obtained by an improved solvothermal method

    NASA Astrophysics Data System (ADS)

    Yu, Jing; Wang, Hui-Jie; Shao, Wei-Jia; Xu, Xiao-Liang

    2014-01-01

    Wettability and the light-trapping effect of FeSe2 particles with a micro-nano hierarchical structure have been investigated. Particles are synthesized by an improved solvothermal method, wherein hexadecyl trimethyl ammonium bromide (CTAB) is employed as a surfactant. After modifying the particles with heptadecafluorodecyltrimethoxy-silane (HTMS), we find that the water contact angle (WCA) of the FeSe2 particles increases by 6.1° and the water sliding angle (WSA) decreases by 2.5° respectively, and the diffuse reflectivity decreases 29.4% compared with similar FeSe2 particles synthesized by the conventional method. The growth process of the particles is analyzed and a growth scenario is given. Upon altering the PH values of the water, we observe that the superhydrophobic property is maintained quite consistently across a wide PH range of 1-14. Moreover, the modified particles were also found to be superoleophobic. To the best of our knowledge, there is no systematic research on the wettability of FeSe2 particles, so our research provides a reference for other researchers.

  14. Laser trapping of Radium and progress towards an electric dipole moment measurement

    NASA Astrophysics Data System (ADS)

    Guest, J. R.; Scielzo, N. D.; Ahmad, I.; Bailey, K.; Greene, J. P.; Holt, R. J.; Lu, Z.-T.; O'Connor, T. P.; Potterveld, D. H.; Gould, H.

    2006-05-01

    Permanent electric dipole moments (EDMs) in atoms or molecules are signatures of Time (T)-and Parity (P)-violation and represent an important window onto physics beyond the Standard Model. We are developing a next generation EDM search around laser-cooled and trapped Ra-225. Due to octupole deformation of the nucleus, Ra-225 is predicted to be two to three orders of magnitude more sensitive to T-violating interactions than Hg-199, which currently sets the most stringent limits in the nuclear sector. We will discuss our progress, including the successful laser cooling and trapping of Ra-226 atoms. Using the ^1S0 F=0 -- ^3P1 F=1 transition, we have demonstrated transverse cooling, Zeeman slowing, and capture of Ra-226 atoms in a magneto-optical trap (MOT). By repumping the ^3D1 dark state to the ^1P1 state, which decays back to ground ^1S0 state, we have extended the lifetime of the trap from milliseconds to seconds.

  15. Evanescent field trapping of nanoparticles using nanostructured ultrathin optical fibers.

    PubMed

    Daly, Mark; Truong, Viet Giang; Chormaic, Síle Nic

    2016-06-27

    While conventional optical trapping techniques can trap objects with submicron dimensions, the underlying limits imposed by the diffraction of light generally restrict their use to larger or higher refractive index particles. As the index and diameter decrease, the trapping difficulty rapidly increases; hence, the power requirements for stable trapping become so large as to quickly denature the trapped objects in such diffraction-limited systems. Here, we present an evanescent field-based device capable of confining low index nanoscale particles using modest optical powers as low as 1.2 mW, with additional applications in the field of cold atom trapping. Our experiment uses a nanostructured optical micro-nanofiber to trap 200 nm, low index contrast, fluorescent particles within the structured region, thereby overcoming diffraction limitations. We analyze the trapping potential of this device both experimentally and theoretically, and show how strong optical traps are achieved with low input powers. PMID:27410600

  16. Search for one- and two-phonon octupole vibrational states in the spherical nuclei near 132Sn

    NASA Astrophysics Data System (ADS)

    Hwang, J. K.; Hamilton, J. H.; Ramayya, A. V.; Luo, Y. X.

    2013-10-01

    Excited high spin states in 135I, 136Xe, 137Cs, 138Ba, 139La, 140Ce and 142Nd with N = 82 are reorganized and interpreted in a different way to find one- phonon octupole vibrational (POV) bands. Two nearly identical (similar) bands with ΔI = 3 are found in these nuclei. From the presence of two nearly identical excited bands with ΔI = 3 in these nuclei, one-POV bands are proposed. Also, high spin states of 134Sb, 134,135Te, 135,136I, 137Xe and 139Ba near 132Sn are reanalyzed in order to search for one- and two-POV states. New spins and parities are tentatively assigned to the 2203.9 keV state in 137Xe and the 1976.6 and 2091.7 keV states in 139Ba from the state energy plots of the N = 82 and 83 nuclei. High spin states of 134Sb, 134,135Te, 135,136I, 137Xe and 139Ba connected by E1, E3 /M2 and E3 transitions are proposed, for the first time, as zero-, one- and two-POV states. One- and two-POV states in 134Sb and 135Te are built on a 7- (πg7/2 ν f7/2) state and a 19 /2- (νf7/2 ⊗ 61+)state, respectively. One-POV states built on the 19 /2- (ν f7/2 ⊗ 61+)and the 21 /2- (νh9/2 ⊗ 62+)states coexist in 137Xe. Then, one- and two-POV states in 139Ba are built only on the 21 /2- (νh9/2 ⊗ 62+)state. One- and two-POV states in 134Te are built on the 62+state with some mixing with the 61+state.

  17. Multivariate Geostatistical Analysis of Uncertainty for the Hydrodynamic Model of a Geological Trap for Carbon Dioxide Storage. Case study: Multilayered Geological Structure Vest Valcele, ROMANIA

    NASA Astrophysics Data System (ADS)

    Scradeanu, D.; Pagnejer, M.

    2012-04-01

    The purpose of the works is to evaluate the uncertainty of the hydrodynamic model for a multilayered geological structure, a potential trap for carbon dioxide storage. The hydrodynamic model is based on a conceptual model of the multilayered hydrostructure with three components: 1) spatial model; 2) parametric model and 3) energy model. The necessary data to achieve the three components of the conceptual model are obtained from: 240 boreholes explored by geophysical logging and seismic investigation, for the first two components, and an experimental water injection test for the last one. The hydrodinamic model is a finite difference numerical model based on a 3D stratigraphic model with nine stratigraphic units (Badenian and Oligocene) and a 3D multiparameter model (porosity, permeability, hydraulic conductivity, storage coefficient, leakage etc.). The uncertainty of the two 3D models was evaluated using multivariate geostatistical tools: a)cross-semivariogram for structural analysis, especially the study of anisotropy and b)cokriging to reduce estimation variances in a specific situation where is a cross-correlation between a variable and one or more variables that are undersampled. It has been identified important differences between univariate and bivariate anisotropy. The minimised uncertainty of the parametric model (by cokriging) was transferred to hydrodynamic model. The uncertainty distribution of the pressures generated by the water injection test has been additional filtered by the sensitivity of the numerical model. The obtained relative errors of the pressure distribution in the hydrodynamic model are 15-20%. The scientific research was performed in the frame of the European FP7 project "A multiple space and time scale approach for the quantification of deep saline formation for CO2 storage(MUSTANG)".

  18. Description of nuclear octupole and quadrupole deformation close to axial symmetry: Critical-point behavior of {sup 224}Ra and {sup 224}Th

    SciTech Connect

    Bizzeti, P. G.; Bizzeti-Sona, A. M.

    2008-02-15

    The model, introduced in a previous paper, for the description of the octupole and quadrupole degrees of freedom in conditions close to axial symmetry, is applied to situations of shape phase transitions where the quadrupole amplitude can reach zero. The transitional nuclei {sup 224,226}Ra and {sup 224}Th are discussed in the frame of this model. Their level schemes can be reasonably accounted for by assuming a square-well potential in two dimensions. Electromagnetic transition amplitudes are also evaluated and compared with existing experimental data.

  19. Evaluating shading bias in malaise and intercept traps

    USGS Publications Warehouse

    Irvine, Kathryn M.; Woods, Stephen A.

    2007-01-01

    Foresters are increasingly focusing on landscape level management regimes. At the landscape level, managed acreage may differ substantially in structure and micro-climatic conditions. Trapping is a commonly used method to evaluate changes in insect communities across landscapes. Among those trapping techniques, Malaise and window-pane traps are conveniently deployed to collect large numbers of insects for relative estimates of density. However, the catch within traps may be affected by a wide range of environmental variables including trap location, height, and factors such as exposure to sunlight and temperature. Seven experiments were conducted from 1996 through 2000 to evaluate the effects of shading on trap catch of a variety of Malaise trap designs and one window-pane trap design. Overall, differences in shading effects on trap catch were detected across different traps and taxa and suggested that, in general, more insects are collected in traps that were in direct sunlight. The effect of shading varied from a reduction in trap catch of 10 % to an increase of 7%, the results depended on trap color. Diptera, Coleoptera, and Homoptera were most likely to exhibit this bias. In contrast, trap catch of the Hymenoptera was the most variable and appeared to be sensitive to factors that might interact with sun/shade conditions

  20. Ball-grid array architecture for microfabricated ion traps

    NASA Astrophysics Data System (ADS)

    Guise, Nicholas D.; Fallek, Spencer D.; Stevens, Kelly E.; Brown, K. R.; Volin, Curtis; Harter, Alexa W.; Amini, Jason M.; Higashi, Robert E.; Lu, Son Thai; Chanhvongsak, Helen M.; Nguyen, Thi A.; Marcus, Matthew S.; Ohnstein, Thomas R.; Youngner, Daniel W.

    2015-05-01

    State-of-the-art microfabricated ion traps for quantum information research are approaching nearly one hundred control electrodes. We report here on the development and testing of a new architecture for microfabricated ion traps, built around ball-grid array (BGA) connections, that is suitable for increasingly complex trap designs. In the BGA trap, through-substrate vias bring electrical signals from the back side of the trap die to the surface trap structure on the top side. Gold-ball bump bonds connect the back side of the trap die to an interposer for signal routing from the carrier. Trench capacitors fabricated into the trap die replace area-intensive surface or edge capacitors. Wirebonds in the BGA architecture are moved to the interposer. These last two features allow the trap die to be reduced to only the area required to produce trapping fields. The smaller trap dimensions allow tight focusing of an addressing laser beam for fast single-qubit rotations. Performance of the BGA trap as characterized with 40Ca+ ions is comparable to previous surface-electrode traps in terms of ion heating rate, mode frequency stability, and storage lifetime. We demonstrate two-qubit entanglement operations with 171Yb+ ions in a second BGA trap.

  1. Ball-grid array architecture for microfabricated ion traps

    SciTech Connect

    Guise, Nicholas D. Fallek, Spencer D.; Stevens, Kelly E.; Brown, K. R.; Volin, Curtis; Harter, Alexa W.; Amini, Jason M.; Higashi, Robert E.; Lu, Son Thai; Chanhvongsak, Helen M.; Nguyen, Thi A.; Marcus, Matthew S.; Ohnstein, Thomas R.; Youngner, Daniel W.

    2015-05-07

    State-of-the-art microfabricated ion traps for quantum information research are approaching nearly one hundred control electrodes. We report here on the development and testing of a new architecture for microfabricated ion traps, built around ball-grid array (BGA) connections, that is suitable for increasingly complex trap designs. In the BGA trap, through-substrate vias bring electrical signals from the back side of the trap die to the surface trap structure on the top side. Gold-ball bump bonds connect the back side of the trap die to an interposer for signal routing from the carrier. Trench capacitors fabricated into the trap die replace area-intensive surface or edge capacitors. Wirebonds in the BGA architecture are moved to the interposer. These last two features allow the trap die to be reduced to only the area required to produce trapping fields. The smaller trap dimensions allow tight focusing of an addressing laser beam for fast single-qubit rotations. Performance of the BGA trap as characterized with {sup 40}Ca{sup +} ions is comparable to previous surface-electrode traps in terms of ion heating rate, mode frequency stability, and storage lifetime. We demonstrate two-qubit entanglement operations with {sup 171}Yb{sup +} ions in a second BGA trap.

  2. Ellipsometrical detection of optical trapped nanoparticles by periodically localized light

    NASA Astrophysics Data System (ADS)

    Taki, Naoya; Mizutani, Yasuhiro; Iwata, Tetsuo; Kojima, Takao; Yamamoto, Hiroki; Kozawa, Takahiro

    2012-04-01

    The purpose of this study is development of a trapping system for nano-particles by periodically localized light and of a detecting system for the trapped state by an ellipsometoric method. Nano-particles are of interest for some different attractive properties with a bulk body in terms of their reactivity. Those attractive properties are applicable to production of an optical element and a device. For production of nano-particles, it is necessary to manipulate nano-particles and to measure the trapped state without contact in micro region. In this study, periodically localized light which is generated by the nano-periodic structure allows us to trap nano-particles. Evaluation of trapping can be accomplished by using a rotating-analyzer ellipsometer for comparing the ellipsometrical parameter before and after trapping. In confirmation of affectivity ellipsometrical method, we obtained that the trapped state associated with varying a shape of the nanoperiodic structure depends on polarization properties. The trapping light intensity also was found to depend on trapping volume of the nano-particles. From experimental results, the nano-particles can be trapped by the periodically localized light. And the trapping volume was found to increase with increasing in trapping light intensity. Hence, this system achieved trapping and deducing nano-particles.

  3. Trap style influences wild pig behavior and trapping success

    USGS Publications Warehouse

    Williams, B.L.; Holtfreter, R.W.; Ditchkoff, S.S.; Grand, J.B.

    2011-01-01

    Despite the efforts of many natural resource professionals, wild pig (Sus scrofa) populations are expanding in many areas of the world. Although many creative techniques for controlling pig populations are being explored, trapping has been and still is themost commonly usedmethod of population control formany public and private land managers. We conducted an observational study to examine the efficiency of 2 frequently used trap styles: a small, portable box-style trap and a larger, semi-permanent, corral-style trap.We used game cameras to examine patterns of trap entry by wild pigs around each style of trap, and we conducted a trapping session to compare trapping success between trap styles. Adult female and juvenile wild pigs entered both styles of trap more readily than did adult males, and adult males seemed particularly averse to entering box traps. Less than 10% of adult male visits to box traps resulted in entries, easily the least percentage of any class at any style of trap. Adult females entered corral traps approximately 2.2 times more often per visit than box traps and re-entered corral traps >2 times more frequently. Juveniles entered and reentered both box and corral traps at similar rates. Overall (all-class) entry-per-visit rates at corral traps (0.71) were nearly double that of box traps (0.37). Subsequent trapping data supported these preliminary entry data; the capture rate for corral traps was >4 times that of box traps. Our data suggest that corral traps are temporally and economically superior to box traps with respect to efficiency; that is, corral traps effectively trap more pigs per trap night at a lower cost per pig than do box traps. ?? 2011 The Wildlife Society.

  4. Dynamics Of Ions In A Radio-Frequency Quadrupole Trap

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Williams, Angelyn P.; Maleki, Lutfollah

    1994-01-01

    Report describes computer-simulation study of motions of various numbers of ions in Paul trap. Study part of continuing effort to understand motions of trapped charged particles (atoms, ions, molecules, or dust particles). Motions characterized in terms of heating by radio-frequency fields, formation of crystallike structures in cold clouds of trapped particles, and other phenomena important in operation of radio-frequency traps in frequency standards.

  5. Ecological and evolutionary traps

    USGS Publications Warehouse

    Schlaepfer, Martin A.; Runge, M.C.; Sherman, P.W.

    2002-01-01

    Organisms often rely on environmental cues to make behavioral and life-history decisions. However, in environments that have been altered suddenly by humans, formerly reliable cues might no longer be associated with adaptive outcomes. In such cases, organisms can become 'trapped' by their evolutionary responses to the cues and experience reduced survival or reproduction. Ecological traps occur when organisms make poor habitat choices based on cues that correlated formerly with habitat quality. Ecological traps are part of a broader phenomenon, evolutionary traps, involving a dissociation between cues that organisms use to make any behavioral or life-history decision and outcomes normally associated with that decision. A trap can lead to extinction if a population falls below a critical size threshold before adaptation to the novel environment occurs. Conservation and management protocols must be designed in light of, rather than in spite of, the behavioral mechanisms and evolutionary history of populations and species to avoid 'trapping' them.

  6. Microfabricated ion trap array

    DOEpatents

    Blain, Matthew G.; Fleming, James G.

    2006-12-26

    A microfabricated ion trap array, comprising a plurality of ion traps having an inner radius of order one micron, can be fabricated using surface micromachining techniques and materials known to the integrated circuits manufacturing and microelectromechanical systems industries. Micromachining methods enable batch fabrication, reduced manufacturing costs, dimensional and positional precision, and monolithic integration of massive arrays of ion traps with microscale ion generation and detection devices. Massive arraying enables the microscale ion traps to retain the resolution, sensitivity, and mass range advantages necessary for high chemical selectivity. The reduced electrode voltage enables integration of the microfabricated ion trap array with on-chip circuit-based rf operation and detection electronics (i.e., cell phone electronics). Therefore, the full performance advantages of the microfabricated ion trap array can be realized in truly field portable, handheld microanalysis systems.

  7. Neutral atom traps.

    SciTech Connect

    Pack, Michael Vern

    2008-12-01

    This report describes progress in designing a neutral atom trap capable of trapping sub millikelvin atom in a magnetic trap and shuttling the atoms across the atom chip from a collection area to an optical cavity. The numerical simulation and atom chip design are discussed. Also, discussed are preliminary calculations of quantum noise sources in Kerr nonlinear optics measurements based on electromagnetically induced transparency. These types of measurements may be important for quantum nondemolition measurements at the few photon limit.

  8. Truly trapped rainbow by utilizing nonreciprocal waveguides

    PubMed Central

    Liu, Kexin; He, Sailing

    2016-01-01

    The concept of a “trapped rainbow” has generated considerable interest for optical data storage and processing. It aims to trap different frequency components of the wave packet at different positions permanently. However, all the previously proposed structures cannot truly achieve this effect, due to the difficulties in suppressing the reflection caused by strong intermodal coupling and distinguishing different frequency components simultaneously. In this article, we found a physical mechanism to achieve a truly “trapped rainbow” storage of electromagnetic wave. We utilize nonreciprocal waveguides under a tapered magnetic field to achieve this and such a trapping effect is stable even under fabrication disorders. We also observe hot spots and relatively long duration time of the trapped wave around critical positions through frequency domain and time domain simulations. The physical mechanism we found has a variety of potential applications ranging from wave harvesting and storage to nonlinearity enhancement. PMID:27453496

  9. Truly trapped rainbow by utilizing nonreciprocal waveguides

    NASA Astrophysics Data System (ADS)

    Liu, Kexin; He, Sailing

    2016-07-01

    The concept of a “trapped rainbow” has generated considerable interest for optical data storage and processing. It aims to trap different frequency components of the wave packet at different positions permanently. However, all the previously proposed structures cannot truly achieve this effect, due to the difficulties in suppressing the reflection caused by strong intermodal coupling and distinguishing different frequency components simultaneously. In this article, we found a physical mechanism to achieve a truly “trapped rainbow” storage of electromagnetic wave. We utilize nonreciprocal waveguides under a tapered magnetic field to achieve this and such a trapping effect is stable even under fabrication disorders. We also observe hot spots and relatively long duration time of the trapped wave around critical positions through frequency domain and time domain simulations. The physical mechanism we found has a variety of potential applications ranging from wave harvesting and storage to nonlinearity enhancement.

  10. Insights into the Mechanism of Bovine CD38/NAD+Glycohydrolase from the X-Ray Structures of Its Michaelis Complex and Covalently-Trapped Intermediates

    PubMed Central

    Egea, Pascal F.; Muller-Steffner, Hélène; Kuhn, Isabelle; Cakir-Kiefer, Céline; Oppenheimer, Norman J.; Stroud, Robert M.; Kellenberger, Esther; Schuber, Francis

    2012-01-01

    Bovine CD38/NAD+glycohydrolase (bCD38) catalyses the hydrolysis of NAD+ into nicotinamide and ADP-ribose and the formation of cyclic ADP-ribose (cADPR). We solved the crystal structures of the mono N-glycosylated forms of the ecto-domain of bCD38 or the catalytic residue mutant Glu218Gln in their apo state or bound to aFNAD or rFNAD, two 2′-fluorinated analogs of NAD+. Both compounds behave as mechanism-based inhibitors, allowing the trapping of a reaction intermediate covalently linked to Glu218. Compared to the non-covalent (Michaelis) complex, the ligands adopt a more folded conformation in the covalent complexes. Altogether these crystallographic snapshots along the reaction pathway reveal the drastic conformational rearrangements undergone by the ligand during catalysis with the repositioning of its adenine ring from a solvent-exposed position stacked against Trp168 to a more buried position stacked against Trp181. This adenine flipping between conserved tryptophans is a prerequisite for the proper positioning of the N1 of the adenine ring to perform the nucleophilic attack on the C1′ of the ribofuranoside ring ultimately yielding cADPR. In all structures, however, the adenine ring adopts the most thermodynamically favorable anti conformation, explaining why cyclization, which requires a syn conformation, remains a rare alternate event in the reactions catalyzed by bCD38 (cADPR represents only 1% of the reaction products). In the Michaelis complex, the substrate is bound in a constrained conformation; the enzyme uses this ground-state destabilization, in addition to a hydrophobic environment and desolvation of the nicotinamide-ribosyl bond, to destabilize the scissile bond leading to the formation of a ribooxocarbenium ion intermediate. The Glu218 side chain stabilizes this reaction intermediate and plays another important role during catalysis by polarizing the 2′-OH of the substrate NAD+. Based on our structural analysis and data on active site mutants

  11. Structural Basis for the Disruption of the Cerebral Cavernous Malformations 2 (CCM2) Interaction with Krev Interaction Trapped 1 (KRIT1) by Disease-associated Mutations*

    PubMed Central

    Fisher, Oriana S.; Liu, Weizhi; Zhang, Rong; Stiegler, Amy L.; Ghedia, Sondhya; Weber, James L.; Boggon, Titus J.

    2015-01-01

    Familial cerebral cavernous malformations (CCMs) are predominantly neurovascular lesions and are associated with mutations within the KRIT1, CCM2, and PDCD10 genes. The protein products of KRIT1 and CCM2 (Krev interaction trapped 1 (KRIT1) and cerebral cavernous malformations 2 (CCM2), respectively) directly interact with each other. Disease-associated mutations in KRIT1 and CCM2 mostly result in loss of their protein products, although rare missense point mutations can also occur. From gene sequencing of patients known or suspected to have one or more CCMs, we discover a series of missense point mutations in KRIT1 and CCM2 that result in missense mutations in the CCM2 and KRIT1 proteins. To place these mutations in the context of the molecular level interactions of CCM2 and KRIT1, we map the interaction of KRIT1 and CCM2 and find that the CCM2 phosphotyrosine binding (PTB) domain displays a preference toward the third of the three KRIT1 NPX(Y/F) motifs. We determine the 2.75 Å co-crystal structure of the CCM2 PTB domain with a peptide corresponding to KRIT1NPX(Y/F)3, revealing a Dab-like PTB fold for CCM2 and its interaction with KRIT1NPX(Y/F)3. We find that several disease-associated missense mutations in CCM2 have the potential to interrupt the KRIT1-CCM2 interaction by destabilizing the CCM2 PTB domain and that a KRIT1 mutation also disrupts this interaction. We therefore provide new insights into the architecture of CCM2 and how the CCM complex is disrupted in CCM disease. PMID:25525273

  12. Alanine Scanning Mutagenesis of Anti-TRAP (AT) Reveals Residues Involved in Binding to TRAP

    PubMed Central

    Chen, Yanling; Gollnick, Paul

    2008-01-01

    SUMMARY The trp RNA-binding attenuation protein (TRAP) regulates expression of the tryptophan biosynthetic (trp) genes in response to changes in intracellular levels of free L-tryptophan in many gram positive bacteria. When activated by binding tryptophan, TRAP binds to the mRNAs of several genes involved in tryptophan metabolism, and down-regulates transcription or translation of these genes. Anti-TRAP (AT) is an antagonist of TRAP that binds to tryptophan-activated TRAP and prevents it from binding to its RNA targets, and thereby up-regulates trp gene expression. The crystal structure shows that AT is a cone-shaped trimer (AT3) with the N-terminal residues of the three subunits assembled at the apex of the cone and that these trimers can further assemble into a dodecameric (AT12) structure. Using alanine-scanning mutagenesis we found four residues, all located on the “top” region of AT3, which are essential for binding to TRAP. Fluorescent labeling experiments further suggest that the top region of AT is in close juxtaposition to TRAP in the AT-TRAP complex. In vivo studies confirmed the importance of these residues on the top of AT in regulating TRAP mediated gene regulation. PMID:18334255

  13. Investigations of the ground-state hyperfine atomic structure and beta decay measurement prospects of {sup 21}Na with improved laser trapping techniques

    SciTech Connect

    Rowe, Mary A.

    1999-05-24

    This thesis describes an experiment in which a neutral atom laser trap loaded with radioactive {sup 21}Na was improved and then used for measurements. The sodium isotope (half-life=22 sec) is produced on line at the 88in cyclotron at Lawrence Berkeley National Laboratory. The author developed an effective magnesium oxide target system which is crucial to deliver a substantive beam of {sup 21}Na to the experiment. Efficient manipulation of the {sup 21}Na beam with lasers allowed 30,000 atoms to be contained in a magneto-optical trap. Using the cold trapped atoms, the author measured to high precision the hyperfine splitting of the atomic ground state of {sup 21}Na. She measured the 3S{sub 1/2}(F=1,m=0)-3S{sub 1/2}(F=2,m=0) atomic level splitting of {sup 21}Na to be 1,906,471,870{+-}200 Hz. Additionally, she achieved initial detection of beta decay from the trap and evaluated the prospects of precision beta decay correlation studies with trapped atoms.

  14. Evaluating the metapopulation consequences of ecological traps.

    PubMed

    Hale, Robin; Treml, Eric A; Swearer, Stephen E

    2015-04-01

    Ecological traps occur when environmental changes cause maladaptive habitat selection. Despite their relevance to metapopulations, ecological traps have been studied predominantly at local scales. How these local impacts scale up to affect the dynamics of spatially structured metapopulations in heterogeneous landscapes remains unexplored. We propose that assessing the metapopulation consequences of traps depends on a variety of factors that can be grouped into four categories: the probability of encounter, the likelihood of selection, the fitness costs of selection and species-specific vulnerability to these costs. We evaluate six hypotheses using a network-based metapopulation model to explore the relative importance of factors across these categories within a spatial context. Our model suggests (i) traps are most severe when they represent a large proportion of habitats, severely reduce fitness and are highly attractive, and (ii) species with high intrinsic fitness will be most susceptible. We provide the first evidence that (iii) traps may be beneficial for metapopulations in rare instances, and (iv) preferences for natal-like habitats can magnify the effects of traps. Our study provides important insight into the effects of traps at landscape scales, and highlights the need to explicitly consider spatial context to better understand and manage traps within metapopulations. PMID:25761712

  15. Acoustic trapping of active matter

    PubMed Central

    Takatori, Sho C.; De Dier, Raf; Vermant, Jan; Brady, John F.

    2016-01-01

    Confinement of living microorganisms and self-propelled particles by an external trap provides a means of analysing the motion and behaviour of active systems. Developing a tweezer with a trapping radius large compared with the swimmers' size and run length has been an experimental challenge, as standard optical traps are too weak. Here we report the novel use of an acoustic tweezer to confine self-propelled particles in two dimensions over distances large compared with the swimmers' run length. We develop a near-harmonic trap to demonstrate the crossover from weak confinement, where the probability density is Boltzmann-like, to strong confinement, where the density is peaked along the perimeter. At high concentrations the swimmers crystallize into a close-packed structure, which subsequently ‘explodes' as a travelling wave when the tweezer is turned off. The swimmers' confined motion provides a measurement of the swim pressure, a unique mechanical pressure exerted by self-propelled bodies. PMID:26961816

  16. Liquid metal cold trap

    DOEpatents

    Hundal, Rolv

    1976-01-01

    A cold trap assembly for removing impurities from a liquid metal being provided with a hole between the incoming impure liquid metal and purified outgoing liquid metal which acts as a continuous bleed means and thus prevents the accumulation of cover gases within the cold trap assembly.

  17. Nonlinear integrable ion traps

    SciTech Connect

    Nagaitsev, S.; Danilov, V.; /SNS Project, Oak Ridge

    2011-10-01

    Quadrupole ion traps can be transformed into nonlinear traps with integrable motion by adding special electrostatic potentials. This can be done with both stationary potentials (electrostatic plus a uniform magnetic field) and with time-dependent electric potentials. These potentials are chosen such that the single particle Hamilton-Jacobi equations of motion are separable in some coordinate systems. The electrostatic potentials have several free adjustable parameters allowing for a quadrupole trap to be transformed into, for example, a double-well or a toroidal-well system. The particle motion remains regular, non-chaotic, integrable in quadratures, and stable for a wide range of parameters. We present two examples of how to realize such a system in case of a time-independent (the Penning trap) as well as a time-dependent (the Paul trap) configuration.

  18. Trapping radioactive ions

    NASA Astrophysics Data System (ADS)

    Kluge, H.-J.; Blaum, K.

    2004-12-01

    Trapping devices for atomic and nuclear physics experiments with radioactive ions are becoming more and more important at accelerator facilities. While about ten years ago only one online Penning trap experiment existed, namely ISOLTRAP at ISOLDE/CERN, meanwhile almost every radioactive beam facility has installed or plans an ion trap setup. This article gives an overview on ion traps in the operation, construction or planing phase which will be used for fundamental studies with short-lived radioactive nuclides such as mass spectrometry, laser spectroscopy and nuclear decay spectroscopy. In addition, this article summarizes the use of gas cells and radiofrequency quadrupole (Paul) traps at different facilities as a versatile tool for ion beam manipulation like retardation, cooling, bunching, and cleaning.

  19. Optically programmable excitonic traps

    PubMed Central

    Alloing, Mathieu; Lemaître, Aristide; Galopin, Elisabeth; Dubin, François

    2013-01-01

    With atomic systems, optically programmed trapping potentials have led to remarkable progress in quantum optics and quantum information science. Programmable trapping potentials could have a similar impact on studies of semiconductor quasi-particles, particularly excitons. However, engineering such potentials inside a semiconductor heterostructure remains an outstanding challenge and optical techniques have not yet achieved a high degree of control. Here, we synthesize optically programmable trapping potentials for indirect excitons of bilayer heterostructures. Our approach relies on the injection and spatial patterning of charges trapped in a field-effect device. We thereby imprint in-situ and on-demand electrostatic traps into which we optically inject cold and dense ensembles of excitons. This technique creates new opportunities to improve state-of-the-art technologies for the study of collective quantum behavior of excitons and also for the functionalisation of emerging exciton-based opto-electronic circuits. PMID:23546532

  20. Low trap states in in situ SiN{sub x}/AlN/GaN metal-insulator-semiconductor structures grown by metal-organic chemical vapor deposition

    SciTech Connect

    Lu, Xing; Ma, Jun; Jiang, Huaxing; Liu, Chao; Lau, Kei May

    2014-09-08

    We report the use of SiN{sub x} grown in situ by metal-organic chemical vapor deposition as the gate dielectric for AlN/GaN metal-insulator-semiconductor (MIS) structures. Two kinds of trap states with different time constants were identified and characterized. In particular, the SiN{sub x}/AlN interface exhibits remarkably low trap state densities in the range of 10{sup 11}–10{sup 12 }cm{sup −2}eV{sup −1}. Transmission electron microscopy and X-ray photoelectron spectroscopy analyses revealed that the in situ SiN{sub x} layer can provide excellent passivation without causing chemical degradation to the AlN surface. These results imply the great potential of in situ SiN{sub x} as an effective gate dielectric for AlN/GaN MIS devices.

  1. An active bubble trap and debubbler for microfluidic systems.

    PubMed

    Skelley, Alison M; Voldman, Joel

    2008-10-01

    We present a novel, fully integrated microfluidic bubble trap and debubbler. The 2-layer structure, based on a PDMS valve design, utilizes a featured membrane to stop bubble progression through the device. A pneumatic chamber directly above the trap is evacuated, and the bubble is pulled out through the gas-permeable PDMS membrane. Normal device operation, including continuous flow at atmospheric pressure, is maintained during the entire trapping and debubbling process. We present a range of trap sizes, from 2 to 10 mm diameter, and can trap and remove bubbles up to 25 microL in under 3 h.

  2. An ion trap built with photonic crystal fibre technology

    SciTech Connect

    Lindenfelser, F. Keitch, B.; Kienzler, D.; Home, J. P.; Bykov, D.; Uebel, P.; Russell, P. St. J.

    2015-03-15

    We demonstrate a surface-electrode ion trap fabricated using techniques transferred from the manufacture of photonic-crystal fibres. This provides a relatively straightforward route for realizing traps with an electrode structure on the 100 micron scale with high optical access. We demonstrate the basic functionality of the trap by cooling a single ion to the quantum ground state, allowing us to measure a heating rate from the ground state of 787 ± 24 quanta/s. Variation of the fabrication procedure used here may provide access to traps in this geometry with trap scales between 100 μm and 10 μm.

  3. Electrical degradation mechanisms of nanoscale charge trap flash memories due to trapped charge in the oxide layer

    NASA Astrophysics Data System (ADS)

    Koh, Kyoung Wook; Kim, Dong Hun; Ryu, Ju Tae; Kim, Tae Whan; Yoo, Keon-Ho

    2015-08-01

    The deterioration of the electrical characteristics of charge trap flash (CTF) memories with a silicon-oxide-nitride-oxide-silicon (SONOS) structure due to the charge traps in the oxide layers attributed to the random trapping and detrapping processes was investigated. Simulation results for the CTF memories showed that the threshold voltage shift was decreased by the charge trapped in the oxide layers in the SONOS structure and that the charge trapped in the blocking oxide had more significant effects than that trapped in the tunneling oxide. The degradation effects of the charge trapped in the blocking oxide on the electrical characteristics of the CTF memories were clarified by examining the vertical electric field in the device.

  4. Modeling of trap-assisted tunneling on performance of charge trapping memory with consideration of trap position and energy level

    NASA Astrophysics Data System (ADS)

    Lun, Zhi-Yuan; Li, Yun; Zhao, Kai; Du, Gang; Liu, Xiao-Yan; Wang, Yi

    2016-08-01

    In this work, the trap-assisted tunneling (TAT) mechanism is modeled as a two-step physical process for charge trapping memory (CTM). The influence of the TAT mechanism on CTM performance is investigated in consideration of various trap positions and energy levels. For the simulated CTM structure, simulation results indicate that the positions of oxide traps related to the maximum TAT current contribution shift towards the substrate interface and charge storage layer interface during time evolutions in programming and retention operations, respectively. Lower programming voltage and retention operations under higher temperature are found to be more sensitive to tunneling oxide degradation. Project supported by the National Natural Science Foundation of China (Grant Nos. 61404005, 61421005, and 91434201).

  5. Steam trap monitor

    DOEpatents

    Ryan, M.J.

    1987-05-04

    A steam trap monitor positioned downstream of a steam trap in a closed steam system includes a first sensor (a hot finger) for measuring the energy of condensate and a second sensor (a cold finger) for measuring the total energy of condensate and steam in the line. The hot finger includes one or more thermocouples for detecting condensate level and energy, while the cold finger contains a liquid with a lower boiling temperature than that of water. Vapor pressure from the liquid is used to do work such as displacing a piston or bellow in providing an indication of total energy (steam + condensate) of the system. Processing means coupled to and responsive to outputs from the hot and cold fingers subtracts the former from the latter to provide an indication of the presence of steam downstream from the trap indicating that the steam trap is malfunctioning. 2 figs.

  6. Trapping and Probing Antihydrogen

    SciTech Connect

    Wurtele, Jonathan

    2013-03-27

    Precision spectroscopy of antihydrogen is a promising path to sensitive tests of CPT symmetry. The most direct route to achieve this goal is to create and probe antihydrogen in a magnetic minimum trap. Antihydrogen has been synthesized and trapped for 1000s at CERN by the ALPHA Collaboration. Some of the challenges associated with achieving these milestones will be discussed, including mixing cryogenic positron and antiproton plasmas to synthesize antihydrogen with kinetic energy less than the trap potential of .5K. Recent experiments in which hyperfine transitions were resonantly induced with microwaves will be presented. The opportunity for gravitational measurements in traps based on detailed studies of antihydrogen dynamics will be described. The talk will conclude with a discussion future antihydrogen research that will use a new experimental apparatus, ALPHA-I.

  7. Versatile electrostatic trap

    SciTech Connect

    Veldhoven, Jacqueline van; Bethlem, Hendrick L.; Schnell, Melanie; Meijer, Gerard

    2006-06-15

    A four electrode electrostatic trap geometry is demonstrated that can be used to combine a dipole, quadrupole, and hexapole field. A cold packet of {sup 15}ND{sub 3} molecules is confined in both a purely quadrupolar and hexapolar trapping field and additionally, a dipole field is added to a hexapole field to create either a double-well or a donut-shaped trapping field. The profile of the {sup 15}ND{sub 3} packet in each of these four trapping potentials is measured, and the dependence of the well-separation and barrier height of the double-well and donut potential on the hexapole and dipole term are discussed.

  8. Innovation: the classic traps.

    PubMed

    Kanter, Rosabeth Moss

    2006-11-01

    Never a fad, but always in or out of fashion, innovation gets rediscovered as a growth enabler every half dozen years. Too often, though, grand declarations about innovation are followed by mediocre execution that produces anemic results, and innovation groups are quietly disbanded in cost-cutting drives. Each managerial generation embarks on the same enthusiastic quest for the next new thing. And each generation faces the same vexing challenges- most of which stem from the tensions between protecting existing revenue streams critical to current success and supporting new concepts that may be crucial to future success. In this article, Harvard Business School professor Rosabeth Moss Kanter reflects on the four major waves of innovation enthusiasm she's observed over the past 25 years. She describes the classic mistakes companies make in innovation strategy, process, structure, and skills assessment, illustrating her points with a plethora of real-world examples--including AT&T Worldnet, Timberland, and Ocean Spray. A typical strategic blunder is when managers set their hurdles too high or limit the scope of their innovation efforts. Quaker Oats, for instance, was so busy in the 1990s making minor tweaks to its product formulas that it missed larger opportunities in distribution. A common process mistake is when managers strangle innovation efforts with the same rigid planning, budgeting, and reviewing approaches they use in their existing businesses--thereby discouraging people from adapting as circumstances warrant. Companies must be careful how they structure fledgling entities alongside existing ones, Kanter says, to avoid a clash of cultures and agendas--which Arrow Electronics experienced in its attempts to create an online venture. Finally, companies commonly undervalue and underinvest in the human side of innovation--for instance, promoting individuals out of innovation teams long before their efforts can pay off. Kanter offers practical advice for avoiding

  9. Atom trap loss, elastic collisions, and technology

    NASA Astrophysics Data System (ADS)

    Booth, James

    2012-10-01

    The study of collisions and scattering has been one of the most productive approaches for modern physics, illuminating the fundamental structure of crystals, surfaces, atoms, and sub-atomic particles. In the field of cold atoms, this is no less true: studies of cold atom collisions were essential to the production of quantum degenerate matter, the formation of cold molecules, and so on. Over the past few years it has been my delight to investigate elastic collisions between cold atoms trapped in either a magneto-optical trap (MOT) or a magnetic trap with hot, background gas in the vacuum environment through the measurement of the loss of atoms from the trap. Motivated by the goal of creating cold atom-based technology, we are deciphering what the trapped atoms are communicating about their environment through the observed loss rate. These measurements have the advantages of being straightforward to implement and they provide information about the underlying, fundamental inter-atomic processes. In this talk I will present some of our recent work, including the observation of the trap depth dependence on loss rate for argon-rubidium collisions. The data follow the computed loss rate curve based on the long-range Van der Waals interaction between the two species. The implications of these findings are exciting: trap depths can be determined from the trap loss measurement under controlled background density conditions; observation of trap loss rate in comparison to models for elastic, inelastic, and chemical processes can lead to improved understanding and characterization of these fundamental interactions; finally the marriage of cold atoms with collision modeling offers the promise of creating a novel pressure sensor and pressure standard for the high and ultra-high vacuum regime.

  10. Reactive Transport Modeling of Geologic CO{sub 2} Sequestration in Saline Aquifers: The Influence of Intra-Aquifer Shales and the Relative Effectiveness of Structural, Solubility, and Mineral Trapping During Prograde and Retrograde Sequestration

    SciTech Connect

    Johnson, J W; Nitao, J J; Steefel, C I; Knauss, K G

    2001-04-24

    In this study, we address a series of fundamental questions regarding the processes and effectiveness of geologic CO{sub 2} sequestration in saline aquifers. We begin with the broadest: what is the ultimate fate of CO{sub 2} injected into these environments? Once injected, it is immediately subject to two sets of competing processes: migration processes and sequestration processes. In terms of migration, the CO{sub 2} moves by volumetric displacement of formation waters, with which it is largely immiscible; by gravity segregation, which causes the immiscible CO{sub 2} plume to rise owing to its relatively low density; and by viscous fingering, owing to its relatively low viscosity. In terms of sequestration, some fraction of the rising plume will dissolve into formation waters (solubility trapping); some fraction may react with formation minerals to precipitate carbonates (mineral trapping); and the remaining portion eventually reaches the cap rock, where it migrates up-dip, potentially accumulating in local topographic highs (structural trapping). Although this concept of competing migration/sequestration processes is intuitively obvious, identifying those sub-processes that dominate the competition is by no means straightforward. Hence, at present there are large uncertainties associated with the ultimate fate of injected CO{sub 2} (Figure 1). Principal among these: can a typical shale cap rock provide a secure seal? Because gravity segregation will always keep the immiscible CO{sub 2} plume moving towards the surface, caprock integrity is the single most important variable influencing isolation security. An extremely thick shale cap rock exists at Sleipner (several 100 m); here, however, we examine the performance of a 25-m-thick cap, which is more representative of the general case. Although the cap rock represents the final barrier to vertical CO{sub 2} migration, what is the effect of intra-aquifer permeability structure? Because this structure directs the

  11. Microfabricated cylindrical ion trap

    DOEpatents

    Blain, Matthew G.

    2005-03-22

    A microscale cylindrical ion trap, having an inner radius of order one micron, can be fabricated using surface micromachining techniques and materials known to the integrated circuits manufacturing and microelectromechanical systems industries. Micromachining methods enable batch fabrication, reduced manufacturing costs, dimensional and positional precision, and monolithic integration of massive arrays of ion traps with microscale ion generation and detection devices. Massive arraying enables the microscale cylindrical ion trap to retain the resolution, sensitivity, and mass range advantages necessary for high chemical selectivity. The microscale CIT has a reduced ion mean free path, allowing operation at higher pressures with less expensive and less bulky vacuum pumping system, and with lower battery power than conventional- and miniature-sized ion traps. The reduced electrode voltage enables integration of the microscale cylindrical ion trap with on-chip integrated circuit-based rf operation and detection electronics (i.e., cell phone electronics). Therefore, the full performance advantages of microscale cylindrical ion traps can be realized in truly field portable, handheld microanalysis systems.

  12. Parameter screening in microfluidics based hydrodynamic single-cell trapping.

    PubMed

    Deng, B; Li, X F; Chen, D Y; You, L D; Wang, J B; Chen, J

    2014-01-01

    Microfluidic cell-based arraying technology is widely used in the field of single-cell analysis. However, among developed devices, there is a compromise between cellular loading efficiencies and trapped cell densities, which deserves further analysis and optimization. To address this issue, the cell trapping efficiency of a microfluidic device with two parallel micro channels interconnected with cellular trapping sites was studied in this paper. By regulating channel inlet and outlet status, the microfluidic trapping structure can mimic key functioning units of previously reported devices. Numerical simulations were used to model this cellular trapping structure, quantifying the effects of channel on/off status and trapping structure geometries on the cellular trapping efficiency. Furthermore, the microfluidic device was fabricated based on conventional microfabrication and the cellular trapping efficiency was quantified in experiments. Experimental results showed that, besides geometry parameters, cellular travelling velocities and sizes also affected the single-cell trapping efficiency. By fine tuning parameters, more than 95% of trapping sites were taken by individual cells. This study may lay foundation in further studies of single-cell positioning in microfluidics and push forward the study of single-cell analysis.

  13. Controlling trapping potentials and stray electric fields in a microfabricated ion trap through design and compensation

    NASA Astrophysics Data System (ADS)

    Doret, S. Charles; Amini, Jason M.; Wright, Kenneth; Volin, Curtis; Killian, Tyler; Ozakin, Arkadas; Denison, Douglas; Hayden, Harley; Pai, C.-S.; Slusher, Richart E.; Harter, Alexa W.

    2012-07-01

    Recent advances in quantum information processing with trapped ions have demonstrated the need for new ion trap architectures capable of holding and manipulating chains of many (>10) ions. Here we present the design and detailed characterization of a new linear trap, microfabricated with scalable complementary metal-oxide-semiconductor (CMOS) techniques, that is well-suited to this challenge. Forty-four individually controlled dc electrodes provide the many degrees of freedom required to construct anharmonic potential wells, shuttle ions, merge and split ion chains, precisely tune secular mode frequencies, and adjust the orientation of trap axes. Microfabricated capacitors on dc electrodes suppress radio-frequency pickup and excess micromotion, while a top-level ground layer simplifies modeling of electric fields and protects trap structures underneath. A localized aperture in the substrate provides access to the trapping region from an oven below, permitting deterministic loading of particular isotopic/elemental sequences via species-selective photoionization. The shapes of the aperture and radio-frequency electrodes are optimized to minimize perturbation of the trapping pseudopotential. Laboratory experiments verify simulated potentials and characterize trapping lifetimes, stray electric fields, and ion heating rates, while measurement and cancellation of spatially-varying stray electric fields permits the formation of nearly-equally spaced ion chains.

  14. Electron Traps at the Ice Surface

    NASA Astrophysics Data System (ADS)

    Bockstedte, Michel; Auburger, Philipp; Michl, Anja

    Water, water clusters and ice possess the fascinating ability to solvate electrons. On the surface of water cluster1 and thin crystalline ice structures on a metal substrate2 long-living solvated electron states were observed that evolve from pre-existing surface traps. The identification of such traps provides important insight into the electronic structure of the water or ice surface, and the dissociative interaction of electrons with adsorbates. Models2,3 based on the bilayer terminated Ih-(0001) surface related such traps to orientational defects or vacancies. So far, the understanding of the electronic structure of the ice surface with the electron traps is incomplete. Here we address this issue including also water ad-structures4 within hybrid density functional theory and many-body perturbation theory (G0W0). We identify a hierachy of traps with increasing vertical electron affinity, ranging from hexagon adrows to clusters of orientational defects and vacancies with dangling OH-groups. Siefermann and Abel, Angew. Chem. Int. Ed. 50, 5264 (2011). Bovensiepen et al., J. Chem. Phys. C 113, 979 (2013). Hermann et al., J. Phys.: cond. matter 20, 225003 (2008). Mehlhorn and Morgenstern, Phys. Rev. Lett. 99, 246101 (2007)

  15. Switching Oxide Traps

    NASA Technical Reports Server (NTRS)

    Oldham, Timothy R.

    2003-01-01

    We consider radiation-induced charge trapping in SiO2 dielectric layers, primarily from the point of view of CMOS devices. However, SiO2 insulators are used in many other ways, and the same defects occur in other contexts. The key studies, which determined the nature of the oxide charge traps, were done primarily on gate oxides in CMOS devices, because that was the main radiation problem in CMOS at one time. There are two major reviews of radiation-induced oxide charge trapping already in the literature, which discuss the subject in far greater detail than is possible here. The first of these was by McLean et al. in 1989, and the second, ten years later, was intended as an update, because of additional, new work that had been reported. Basically, the picture that has emerged is that ionizing radiation creates electron-hole pairs in the oxide, and the electrons have much higher mobility than the holes. Therefore, the electrons are swept out of the oxide very rapidly by any field that is present, leaving behind any holes that escape the initial recombination process. These holes then undergo a polaron hopping transport toward the Si/SiO2 interface (under positive bias). Near the interface, some fraction of them fall into deep, relatively stable, long-lived hole traps. The nature and annealing behavior of these hole traps is the main focus of this paper.

  16. Discovery of {sup 229}Rn and the Structure of the Heaviest Rn and Ra Isotopes from Penning-Trap Mass Measurements

    SciTech Connect

    Neidherr, D.; Boehm, Ch.; Audi, G.; Lunney, D.; Minaya-Ramirez, E.; Naimi, S.; Beck, D.; Herfurth, F.; Blaum, K.; George, S.; Kellerbauer, A.; Breitenfeldt, M.; Rosenbusch, M.; Schweikhard, L.; Cakirli, R. B.; Casten, R. F.; Herlert, A.; Kowalska, M.; Noah, E.; Penescu, L.

    2009-03-20

    The masses of the neutron-rich radon isotopes {sup 223-229}Rn have been determined for the first time, using the ISOLTRAP setup at CERN ISOLDE. In addition, this experiment marks the first discovery of a new nuclide, {sup 229}Rn, by Penning-trap mass measurement. The new, high-accuracy data allow a fine examination of the mass surface, via the valence-nucleon interaction {delta}V{sub pn}. The results reveal intriguing behavior, possibly reflecting either a N=134 subshell closure or an octupolar deformation in this region.

  17. Thermoelectrically cooled water trap

    DOEpatents

    Micheels, Ronald H.

    2006-02-21

    A water trap system based on a thermoelectric cooling device is employed to remove a major fraction of the water from air samples, prior to analysis of these samples for chemical composition, by a variety of analytical techniques where water vapor interferes with the measurement process. These analytical techniques include infrared spectroscopy, mass spectrometry, ion mobility spectrometry and gas chromatography. The thermoelectric system for trapping water present in air samples can substantially improve detection sensitivity in these analytical techniques when it is necessary to measure trace analytes with concentrations in the ppm (parts per million) or ppb (parts per billion) partial pressure range. The thermoelectric trap design is compact and amenable to use in a portable gas monitoring instrumentation.

  18. Ion trap device

    DOEpatents

    Ibrahim, Yehia M.; Smith, Richard D.

    2016-01-26

    An ion trap device is disclosed. The device includes a series of electrodes that define an ion flow path. A radio frequency (RF) field is applied to the series of electrodes such that each electrode is phase shifted approximately 180 degrees from an adjacent electrode. A DC voltage is superimposed with the RF field to create a DC gradient to drive ions in the direction of the gradient. A second RF field or DC voltage is applied to selectively trap and release the ions from the device. Further, the device may be gridless and utilized at high pressure.

  19. Asymmetric ion trap

    DOEpatents

    Barlow, Stephan E.; Alexander, Michael L.; Follansbee, James C.

    1997-01-01

    An ion trap having two end cap electrodes disposed asymmetrically about a center of a ring electrode. The inner surface of the end cap electrodes are conformed to an asymmetric pair of equipotential lines of the harmonic formed by the application of voltages to the electrodes. The asymmetry of the end cap electrodes allows ejection of charged species through the closer of the two electrodes which in turn allows for simultaneously detecting anions and cations expelled from the ion trap through the use of two detectors charged with opposite polarity.

  20. Asymmetric ion trap

    DOEpatents

    Barlow, S.E.; Alexander, M.L.; Follansbee, J.C.

    1997-12-02

    An ion trap having two end cap electrodes disposed asymmetrically about a center of a ring electrode is disclosed. The inner surface of the end cap electrodes are conformed to an asymmetric pair of equipotential lines of the harmonic formed by the application of voltages to the electrodes. The asymmetry of the end cap electrodes allows ejection of charged species through the closer of the two electrodes which in turn allows for simultaneously detecting anions and cations expelled from the ion trap through the use of two detectors charged with opposite polarity. 4 figs.

  1. The Reusable Astronomy Portal (TRAP)

    NASA Astrophysics Data System (ADS)

    Donaldson, T.; Rogers, A.; Wallace, G.

    2012-09-01

    The Reusable Astronomy Portal (TRAP) aims to provide a common platform for rapidly deploying Astronomy Archives to the web. TRAP is currently under development for both the VAO Data Discovery Portal and the MAST Multi-Mission Portal (Figure 1). TRAP consists of 2 major software packages: the TRAP Client and the TRAP Server. The TRAP framework allows developers to deploy the Server, connect to data resources, then focus on building custom tools for the Client. TRAP is built upon proven industry technologies including the Ext/JS JavaScript Component Library, Mono.NET Web Services, and JSON message based APIs. The multi-layered architecture of TRAP decouples each layer: Client, Service and Data Access, enabling each to evolve independently over time. Although currently deployed to provide astronomy science data access, the TRAP architecture is flexible enough to thrive in any distributed data environment.

  2. Interface/border trap characterization of Al{sub 2}O{sub 3}/AlN/GaN metal-oxide-semiconductor structures with an AlN interfacial layer

    SciTech Connect

    Liu, Shenghou; Yang, Shu; Tang, Zhikai; Jiang, Qimeng; Liu, Cheng; Chen, Kevin J.; Wang, Maojun; Shen, Bo

    2015-02-02

    We report the interface characterization of Al{sub 2}O{sub 3}/AlN/GaN MOS (metal-oxide-semiconductor) structures with an AlN interfacial layer. A thin monocrystal-like interfacial layer (AlN) is formed at the Al{sub 2}O{sub 3}/GaN to effectively block oxygen from the GaN surface and prevent the formation of detrimental Ga-O bonds. The suppression of Ga-O bonds is validated by X-ray photoelectron spectroscopy of the critical interface. Frequency-dispersion in C-V characteristics has been significantly reduced, owing to improved interface quality. Furthermore, using the conventional conductance method suitable for extracting the interface trap density D{sub it} in MOS structures, D{sub it} in the device with AlN was determined to be in the range of 10{sup 11}–10{sup 12 }eV{sup −1 }cm{sup −2}, showing one order of magnitude lower than that without AlN. Border traps near the gate-dielectric/GaN interface were identified and shown to be suppressed by the AlN interfacial layer as well.

  3. Measurement of Trap Length for an Optical Trap

    NASA Technical Reports Server (NTRS)

    Wrbanek, Susan Y.

    2009-01-01

    The trap length along the beam axis for an optical trap formed with an upright, oil-immersion microscope was measured. The goals for this effort were twofold. It was deemed useful to understand the depth to which an optical trap can reach for purposes of developing a tool to assist in the fabrication of miniature devices. Additionally, it was desired to know whether the measured trap length favored one or the other of two competing theories to model an optical trap. The approach was to trap a microsphere of known size and mass and raise it from its initial trap position. The microsphere was then dropped by blocking the laser beam for a pre-determined amount of time. Dropping the microsphere in a free-fall mode from various heights relative to the coverslip provides an estimate of how the trapping length changes with depth in water in a sample chamber on a microscope slide. While it was not possible to measure the trap length with sufficient precision to support any particular theory of optical trap formation, it was possible to find regions where the presence of physical boundaries influenced optical traps, and determine that the trap length, for the apparatus studied, is between 6 and 7 m. These results allow more precise control using optical micromanipulation to assemble miniature devices by providing information about the distance over which an optical trap is effective.

  4. Ultrahigh-performance liquid chromatography-ion trap mass spectrometry characterization of the steroidal saponins of Dioscorea panthaica Prain et Burkill and its application for accelerating the isolation and structural elucidation of steroidal saponins.

    PubMed

    Wang, Weihao; Zhao, Ye; Jing, Wenguang; Zhang, Jun; Xiao, Hui; Zha, Qin; Liu, An

    2015-03-01

    Dioscorea panthaica is a traditional Chinese medicinal herb used in the treatment of various physiological conditions, including cardiovascular disease, gastropathy and hypertension. Steroidal saponins (SS) are the main active ingredients of this herb and have effects on myocardial ischemia and cancer. The phytochemical evaluation of SS is both time-consuming and laborious, and the isolation and structural determination steps can be especially demanding. For this reason, the development of new methods to accelerate the processes involved in the identification, isolation and structural elucidation of SS is highly desirable. In this study, a new ultrahigh performance liquid chromatography-ion trap mass spectrometry (UHPLC-IT/MS(n)) method has been developed for the identification of the SS in D. panthaica Prain et Burkill. Notably, the current method can distinguish between spirostanol and furostanol-type compounds based on the fragmentation patterns observed by electrospray ionization-ion trap mass spectrometry (ESI-IT/MS(n)) analysis. UHPLC-IT/MS(n) was used to conduct a detailed investigation of the number, structural class and order of the sugar moieties in the sugar chains of the SS present in D. panthaica. The established fragmentation features were used to analyze the compounds found in the 65% ethanol fraction of the water extracts of D. panthaica. Twenty-three SS were identified, including 11 potential new compounds and six groups of isomers. Two of these newly identified SS were selected as representative examples, and their chemical structures were confirmed by (1)H and (13)C NMR analyses. This newly developed UHPLC-IT/MS(n) method therefore allowed for the efficient identification, isolation and structural determination of the SS in D. panthaica.

  5. Ultrahigh-performance liquid chromatography-ion trap mass spectrometry characterization of the steroidal saponins of Dioscorea panthaica Prain et Burkill and its application for accelerating the isolation and structural elucidation of steroidal saponins.

    PubMed

    Wang, Weihao; Zhao, Ye; Jing, Wenguang; Zhang, Jun; Xiao, Hui; Zha, Qin; Liu, An

    2015-03-01

    Dioscorea panthaica is a traditional Chinese medicinal herb used in the treatment of various physiological conditions, including cardiovascular disease, gastropathy and hypertension. Steroidal saponins (SS) are the main active ingredients of this herb and have effects on myocardial ischemia and cancer. The phytochemical evaluation of SS is both time-consuming and laborious, and the isolation and structural determination steps can be especially demanding. For this reason, the development of new methods to accelerate the processes involved in the identification, isolation and structural elucidation of SS is highly desirable. In this study, a new ultrahigh performance liquid chromatography-ion trap mass spectrometry (UHPLC-IT/MS(n)) method has been developed for the identification of the SS in D. panthaica Prain et Burkill. Notably, the current method can distinguish between spirostanol and furostanol-type compounds based on the fragmentation patterns observed by electrospray ionization-ion trap mass spectrometry (ESI-IT/MS(n)) analysis. UHPLC-IT/MS(n) was used to conduct a detailed investigation of the number, structural class and order of the sugar moieties in the sugar chains of the SS present in D. panthaica. The established fragmentation features were used to analyze the compounds found in the 65% ethanol fraction of the water extracts of D. panthaica. Twenty-three SS were identified, including 11 potential new compounds and six groups of isomers. Two of these newly identified SS were selected as representative examples, and their chemical structures were confirmed by (1)H and (13)C NMR analyses. This newly developed UHPLC-IT/MS(n) method therefore allowed for the efficient identification, isolation and structural determination of the SS in D. panthaica. PMID:25575790

  6. Experiments with trapped ^210Fr

    NASA Astrophysics Data System (ADS)

    Sprouse, G. D.; Orozco, L. A.; Shi, W.; Simsarian, J. E.; Zhao, W. Z.

    1996-05-01

    Francium, the heaviest of alkali atoms, is an excellent system for the study of weak interactions in atoms because of its large atomic number. It has been difficult to study its atomic structure in great detail since there are no stable isotopes and sufficient quantities have not been available. At the Stony Brook Superconducting LINAC we produce 1 × 10^6 ^210Fr/s in the reaction ^197Au(^18O,5n)^210Fr. The atoms are transported as ions to the vicinity of the trap where they are neutralized and enter the capturing region of a Magneto-Optical Trap (MOT). From the initial [1] capture of ^210Fr into a MOT we have increased the number of atoms to the point where their fluorescence is visible in a CCD camera. The large number of atoms permits the initiation of experiments to study the atomic structure of francium relevant for a parity non-conservation measurement, such as the location of the 8S and 9S electronic states. Work supported by a Precision Measurement Grant from NIST and by NSF. [1] P. A. Voytas, A. Ghosh, G. Gwinner, L. A. Orozco, J. E. Simsarian, G. D. Sprouse, Postdeadline paper APS NPD, Indiana, October 1995; J. E. Simsarian, A. Ghosh, G. Gwinner, L. A. Orozco, G. D. Sprouse and P. A. Voytas (Preprint Dec. 12, 1995).

  7. Trapped particle optical microscopy

    NASA Astrophysics Data System (ADS)

    Malmqvist, Lars; Hertz, Hans M.

    1992-11-01

    A scanned probe optical microscope allowing nondestructive studies of a wide range of objects and surface is described. The microscope utilizes a noninvasive optical trap to position a microscopic probe light source in immediate proximity to the studied object. We demonstrate the method experimentally and show theoretically its potential for optical imaging with subdiffraction limited resolution of, e.g., biological objects.

  8. WATER-TRAPPED WORLDS

    SciTech Connect

    Menou, Kristen

    2013-09-01

    Although tidally locked habitable planets orbiting nearby M-dwarf stars are among the best astronomical targets to search for extrasolar life, they may also be deficient in volatiles and water. Climate models for this class of planets show atmospheric transport of water from the dayside to the nightside, where it is precipitated as snow and trapped as ice. Since ice only slowly flows back to the dayside upon accumulation, the resulting hydrological cycle can trap a large amount of water in the form of nightside ice. Using ice sheet dynamical and thermodynamical constraints, I illustrate how planets with less than about a quarter the Earth's oceans could trap most of their surface water on the nightside. This would leave their dayside, where habitable conditions are met, potentially dry. The amount and distribution of residual liquid water on the dayside depend on a variety of geophysical factors, including the efficiency of rock weathering at regulating atmospheric CO{sub 2} as dayside ocean basins dry up. Water-trapped worlds with dry daysides may offer similar advantages as land planets for habitability, by contrast with worlds where more abundant water freely flows around the globe.

  9. Steam trap monitor

    DOEpatents

    Ryan, Michael J.

    1988-01-01

    A steam trap monitor positioned downstream of a steam trap in a closed steam system includes a first sensor (the combination of a hot finger and thermocouple well) for measuring the energy of condensate and a second sensor (a cold finger) for measuring the total energy of condensate and steam in the line. The hot finger includes one or more thermocouples for detecting condensate level and energy, while the cold finger contains a liquid with a lower boiling temperature than that of water. Vapor pressure from the liquid is used to do work such as displacing a piston or bellows in providing an indication of total energy (steam+condensate) of the system. Processing means coupled to and responsive to outputs from the thermocouple well hot and cold fingers subtracts the condensate energy as measured by the hot finger and thermocouple well from the total energy as measured by the cold finger to provide an indication of the presence of steam downstream from the trap indicating that the steam trap is malfunctioning.

  10. Rotating Saddle Paul Trap.

    ERIC Educational Resources Information Center

    Rueckner, Wolfgang; And Others

    1995-01-01

    Describes a demonstration in which a ball is placed in an unstable position on a saddle shape. The ball becomes stable when it is rotated above some threshold angular velocity. The demonstration is a mechanical analog of confining a particle in a "Paul Trap". (DDR)

  11. The Universal Trap.

    ERIC Educational Resources Information Center

    Goodman, Paul

    The compulsory system of education is criticized on the grounds that it has become a regimented "universal trap" antithetical to democracy. In contrast to the Jeffersonian concept of education in the service of citizen initiative for the preservation of freedom, current compulsory education is a tool of industrialism and of a rigidly stratified…

  12. Traps and trapping techniques for adult mosquito control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An overview is presented of the recent advancements in research activities conducted to evaluate mosquito traps, insecticide-impregnated targets baited with combinations of attractants, and strategies for using mass trapping techniques for adult mosquito population management. Technologies that use...

  13. Controlling the efficiency of trapping in treelike fractals.

    PubMed

    Wu, Bin; Zhang, Zhongzhi

    2013-07-14

    Efficiently controlling the trapping process, especially the trapping efficiency, is central in the study of trap problem in complex systems, since it is a fundamental mechanism for diverse other dynamic processes. Thus, it is of theoretical and practical significance to study the control technique for trapping problem. In this paper, we study the trapping problem in a family of proposed directed fractals with a deep trap at a central node. The directed fractals are a generalization of previous undirected fractals by introducing the directed edge weights dominated by a parameter. We characterize all the eigenvalues and their degeneracies for an associated matrix governing the trapping process. The eigenvalues are provided through an exact recursive relation deduced from the self-similar structure of the fractals. We also obtain the expressions for the smallest eigenvalue and the mean first-passage time (MFPT) as a measure of trapping efficiency, which is the expected time for the walker to first visit the trap. The MFPT is evaluated according to the proved fact that it is approximately equal to reciprocal of the smallest eigenvalue. We show that the MFPT is controlled by the weight parameter by modifying which the MFPT can scale superlinealy, linearly, or sublinearly with the system size. Thus, this work paves a way to delicately controlling the trapping process in the fractals.

  14. A Scalable Microfabricated Ion Trap for Quantum Information Processing

    NASA Astrophysics Data System (ADS)

    Maunz, Peter; Haltli, Raymond; Hollowell, Andrew; Lobser, Daniel; Mizrahi, Jonathan; Rembetski, John; Resnick, Paul; Sterk, Jonathan D.; Stick, Daniel L.; Blain, Matthew G.

    2016-05-01

    Trapped Ion Quantum Information Processing (QIP) relies on complex microfabricated trap structures to enable scaling of the number of quantum bits. Building on previous demonstrations of surface-electrode ion traps, we have designed and characterized the Sandia high-optical-access (HOA-2) microfabricated ion trap. This trap features high optical access, high trap frequencies, low heating rates, and negligible charging of dielectric trap components. We have observed trap lifetimes of more than 100h, measured trap heating rates for ytterbium of less than 40quanta/s, and demonstrated shuttling of ions from a slotted to an above surface region and through a Y-junction. Furthermore, we summarize demonstrations of high-fidelity single and two-qubit gates realized in this trap. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000. This work was supported by the Intelligence Advanced Research Projects Activity (IARPA).

  15. Determination of the B(E3, 0+ → 3-)-excitation strength in octupole-correlated nuclei near A ≈ 224 by the means of Coulomb excitation at REX-ISOLDE

    NASA Astrophysics Data System (ADS)

    Scheck, M.; Gaffney, L. P.; Butler, P. A.; Hayes, A. B.; Wenander, F.; Albers, M.; Bastin, B.; Bauer, C.; Blazhev, A.; Bönig, S.; Bree, N.; Cederkäil, J.; Chupp, T.; Cline, D.; Cocolios, T. E.; Davinson, T.; De Witte, H.; Diriken, J.; Grahn, T.; Gregor, E. T.; Herzan, A.; Huyse, M.; Jenkins, D. G.; Joss, D. T.; Kesteloot, N.; Konki, J.; Kowalczyk, M.; Kröll, Th; Kwan, E.; Lutter, R.; Moschner, K.; Napiorkowski, P.; Pakarinen, J.; Pfeiffer, M.; Radeck, D.; Reiter, P.; Reynders, K.; Rigby, S. V.; Robledo, L. M.; Rudigier, M.; Sambi, S.; Seidlitz, M.; Siebeck, B.; Stora, T.; Thoele, P.; Van Duppen, P.; Vermeulen, M. J.; von Schmid, M.; Voulot, D.; Warr, N.; Wimmer, K.; Wrzosek-Lipska, K.; Wu, C. Y.; Zielińska, M.

    2014-09-01

    The IS475 collaboration conducted Coulomb-excitation experiments with postaccelerated radioactive 220Rn and 224Ra beams at the REX-ISOLDE facility. The beam particles (Ebeam ≈ 2.83 MeV/u) were Coulomb excited using 60Ni, 114Cd, and 120Sn scattering targets. De-excitation γ-rays were detected employing the Miniball array and scattered particles were detected in a silicon detector. Exploiting the Coulomb-excitation code GOSIA for each nucleus several matrix elements could be obtained from the measured γ-ray yields. The extracted langle3-||Ê3||0+rangle matrix element allows for the conclusion that, while 220Rn represents an octupole vibrational system, 224Ra has already substantial octupole correlations in its ground state. An observation that has implications for the search of CP-violating Schiff moments in the atomic systems of the adjacent odd-mass nuclei.

  16. Development of neutral atom traps based on a microfabricated waveguide

    NASA Astrophysics Data System (ADS)

    Jau, Yuan-Yu; Lee, Jongmin; Biedermann, Grant; Siddiqui, Aleem; Eichenfield, Matt; Dougla, Erica

    2016-05-01

    Implementation of trapping neutral atoms in the evanescent fields generated by a nano-structure, such as a nanofiber or a microfabricated nano-waveguide, will naturally enable strong atom-photon interactions, which serve the key mechanisms for different type of quantum controls. At Sandia National Labs, we are aiming to develop a platform based on this concept to eventually trap cesium atoms with a microfabricated waveguide. Although, neutral atom traps using optical nanofiber has been demonstrated, there are several key issues that need to be resolved to realize trapping atoms with microfabricated structure. The subjects include the material for making the waveguide, optical power handling capability, surface adsorption of alkali-metal atoms, surface roughness of the nano-structure, cold-atom source for loading the atoms into the evanescent-field traps, etc. We will discuss our studies on these related subjects and report our latest progress.

  17. Newly discovered landscape traps produce regime shifts in wet forests

    PubMed Central

    Lindenmayer, David B.; Hobbs, Richard J.; Likens, Gene E.; Krebs, Charles J.; Banks, Samuel C.

    2011-01-01

    We describe the “landscape trap” concept, whereby entire landscapes are shifted into, and then maintained (trapped) in, a highly compromised structural and functional state as the result of multiple temporal and spatial feedbacks between human and natural disturbance regimes. The landscape trap concept builds on ideas like stable alternative states and other relevant concepts, but it substantively expands the conceptual thinking in a number of unique ways. In this paper, we (i) review the literature to develop the concept of landscape traps, including their general features; (ii) provide a case study as an example of a landscape trap from the mountain ash (Eucalyptus regnans) forests of southeastern Australia; (iii) suggest how landscape traps can be detected before they are irrevocably established; and (iv) present evidence of the generality of landscape traps in different ecosystems worldwide. PMID:21876151

  18. Compact toroidal ion-trap design and optimization

    SciTech Connect

    Madsen, M. J.; Gorman, C. H.

    2010-10-15

    We present the design of a type of compact toroidal, or 'halo', ion trap. Such traps may be useful for mass spectrometry, studying small Coulomb cluster rings, quantum-information applications, or other quantum simulations where a ring topology is of interest. We present results from a Monte Carlo optimization of the trap design parameters using finite-element analysis simulations that minimize higher-order anharmonic terms in the trapping pseudopotential, while maintaining complete control over ion placement at the pseudopotential node in three dimensions using static bias fields. These simulations are based on a practical electrode design using readily available parts, yet can be easily scaled to any size trap with similar electrode spacings. We also derive the conditions for a crystal structure transition for two ions in the compact halo trap, the first nontrivial transition for Coulomb crystals in this geometry.

  19. Antihydrogen Trapped in the ALPHA Experiment

    SciTech Connect

    2011-02-25

    In 2010 the ALPHA collaboration succeeded in trapping antihydrogen atoms for the first time.[i]  Stored antihydrogen promises to be a unique tool for making high precision measurements of the structure of this first anti-atom. Achieving this milestone presented several substantial experimental challenges and this talk will describe how they were overcome.   The unique design features of the ALPHA apparatus will be explained.[ii]  These allow a high intensity positron source and an antiproton imaging detector similar to the one used in the ATHENA[iii] experiment to be combined with an innovative magnet design of the anti-atom trap. This seeks to minimise the perturbations to trapped charged particles which may cause particle loss and heating[iv].   The diagnostic techniques used to measure the diameter, number, density, and temperatures of both plasmas will be presented as will the methods developed to actively compress and cool of both plasma species to sizes and temperatures [v],[vi], [vii] where trapping attempts with a reasonable chance of success can be tried.   The results of the successful trapping experiments will be outlined as well as some subsequent experiments to improve the trapping rate and storage time. [i] 'Trapped antihydrogen' G.B. Andresen et al., Nature 468, 673 (2010) [ii]'A Magnetic Trap for Antihydrogen Confinement' W. Bertsche et al., Nucl. Instr. Meth. Phys. Res. A566, 746 (2006) [iii] Production and detection of cold antihydrogen atoms M.Amoretti et al., Nature 419, 456 (2002). [iv]' Antihydrogen formation dynamics in a multipolar neutral anti-atom trap' G.B. Andresen et al., Phys. Lett. B 685, 141 (2010) [v]' Evaporative Cooling of Antiprotons to Cryogenic Temperatures',                                   G.B. Andresen et al. Phys. Rev. Lett 105, 013003 (2010) [vi]'Compression of Antiproton Clouds for Antihydrogen Trapping' G. B. Andresen et al. Phys. Rev. Lett 100, 203401 (2008) [vii]  'Autoresonant

  20. Antihydrogen Trapped in the ALPHA Experiment

    ScienceCinema

    None

    2016-07-12

    In 2010 the ALPHA collaboration succeeded in trapping antihydrogen atoms for the first time.[i]  Stored antihydrogen promises to be a unique tool for making high precision measurements of the structure of this first anti-atom. Achieving this milestone presented several substantial experimental challenges and this talk will describe how they were overcome.   The unique design features of the ALPHA apparatus will be explained.[ii]  These allow a high intensity positron source and an antiproton imaging detector similar to the one used in the ATHENA[iii] experiment to be combined with an innovative magnet design of the anti-atom trap. This seeks to minimise the perturbations to trapped charged particles which may cause particle loss and heating[iv].   The diagnostic techniques used to measure the diameter, number, density, and temperatures of both plasmas will be presented as will the methods developed to actively compress and cool of both plasma species to sizes and temperatures [v],[vi], [vii] where trapping attempts with a reasonable chance of success can be tried.   The results of the successful trapping experiments will be outlined as well as some subsequent experiments to improve the trapping rate and storage time. [i] 'Trapped antihydrogen' G.B. Andresen et al., Nature 468, 673 (2010) [ii]'A Magnetic Trap for Antihydrogen Confinement' W. Bertsche et al., Nucl. Instr. Meth. Phys. Res. A566, 746 (2006) [iii] Production and detection of cold antihydrogen atoms M.Amoretti et al., Nature 419, 456 (2002). [iv]' Antihydrogen formation dynamics in a multipolar neutral anti-atom trap' G.B. Andresen et al., Phys. Lett. B 685, 141 (2010) [v]' Evaporative Cooling of Antiprotons to Cryogenic Temperatures',                                   G.B. Andresen et al. Phys. Rev. Lett 105, 013003 (2010) [vi]'Compression of Antiproton Clouds for Antihydrogen Trapping' G. B. Andresen et al. Phys. Rev. Lett 100, 203401 (2008) [vii]  'Autoresonant

  1. Global gyrokinetic simulations of trapped-electron mode and trapped-ion mode microturbulence

    NASA Astrophysics Data System (ADS)

    Drouot, T.; Gravier, E.; Reveille, T.; Sarrat, M.; Collard, M.; Bertrand, P.; Cartier-Michaud, T.; Ghendrih, P.; Sarazin, Y.; Garbet, X.

    2015-08-01

    This paper presents a reduced kinetic model, which describes simultaneously trapped-ion (TIM) and trapped-electron (TEM) driven modes. Interestingly, the model enables the study of a full f problem for ion and electron trapped particles at very low numerical cost. The linear growth rate obtained with the full f nonlinear code Trapped Element REduction in Semi Lagrangian Approach is successfully compared with analytical predictions. Moreover, nonlinear results show some basic properties of collisionless TEM and TIM turbulence in tokamaks. A competition between streamer-like structures and zonal flows is observed for TEM and TIM turbulence. Zonal flows are shown to play an important role in suppressing the nonlinear transport and strongly depend on the temperature ratio Te/Ti .

  2. Atom trapping with a thin magnetic film

    SciTech Connect

    Boyd, Micah; Streed, Erik W.; Medley, Patrick; Campbell, Gretchen K.; Mun, Jongchul; Ketterle, Wolfgang; Pritchard, David E.

    2007-10-15

    We have created a {sup 87}Rb Bose-Einstein condensate in a magnetic trapping potential produced by a hard disk platter written with a periodic pattern. Cold atoms were loaded from an optical dipole trap and then cooled to Bose-Einstein condensation on the surface with radio-frequency evaporation. Fragmentation of the atomic cloud due to imperfections in the magnetic structure was observed at distances closer than 40 {mu}m from the surface. Attempts to use the disk as an atom mirror showed dispersive effects after reflection.

  3. Soil conservation through sediment trapping: A review

    NASA Astrophysics Data System (ADS)

    Mekonnen, Mulatie; Keesstra, Saskia; Baartman, Jantiene; Maroulis, Jerry; Stroosnijder, Leo

    2014-05-01

    Preventing the off-site effects of soil erosion is an essential part of good catchment management. Most efforts are in the form of on-site soil and water conservation measures. However, sediment trapping (ST) can be an alternative (or additional) measure to prevent the negative off-site effects of soil erosion. Therefore, not all efforts should focus solely on on-site soil conservation, but also on the safe routing of sediment-laden flows and on creating sites and conditions where sediment can be trapped, preferably in a cost effective or even profitable way. ST can be applied on-site (in-field) and off-site and involves both vegetative and structural measures. The main vegetative measures include grass strips, tree or bush buffers, grassed waterways and restoration of the waterways and their riparian zone; while structural measures include terraces, ponds and check dams. This paper provides a review of studies that have assessed the sediment trapping efficacy (STE) of such vegetative and structural measures. Vegetation type and integration of two or more measures (vegetative as well as structural) are important factors influencing STE. In this review, the STE of most measures was evaluated either individually or in such combinations. In real landscape situations, it is not only important to select the most efficient erosion control measures, but also to determine their optimum location in the catchment. Hence, there is a need for research that shows a more integrated determination of STE at the catchment scale. If integrated measures are implemented at the most appropriate spatial locations within a catchment where they can disconnect landscape units from each other, they will decrease runoff velocity and sediment transport and, subsequently, reduce downstream flooding and sedimentation problems. KEY WORDS: Integrated sediment trapping, sediment trapping efficacy, vegetative, structural, on-site and off-site measures.

  4. Radial cold trap

    DOEpatents

    Grundy, B.R.

    1981-09-29

    The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume. 2 figs.

  5. Radial cold trap

    DOEpatents

    Grundy, Brian R.

    1981-01-01

    The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume.

  6. Progress Towards a Practical Multicell Positron Trap

    NASA Astrophysics Data System (ADS)

    Danielson, J. R.

    2013-10-01

    The physics and technology of positron confinement is central to a range of applications at the forefront of antimatter science. Progress in this area has been driven by the development of a suite of novel non-neutral plasma techniques whereby up to 4 ×109 positrons have now been trapped and stored. However the next generation of experiments will require orders of magnitude more positrons. This talk describes techniques to increase storage capacity to >=1012 using a novel multi-cell trap architecture. Plasmas will be stored in separate Penning-Malmberg traps (``cells'') arranged in parallel off the magnetic axis to maximize use of the magnetic field volume while minimizing the required confinement voltages. Experiments with electrons in a test structure will be described to explore the basic physics and technology of the multicell concept and to set the design of a 21-cell trap for 1012 positrons. Over 50% of a trapped plasma has been injected into an off-axis cell, and hour-long confinement of 2 ×108 particles has been achieved using rotating electric fields. Experiments are under way to identify the limits of the injection process and demonstrate confinement >1010 particles in a single off-axis cell using kilovolt confinement potentials. In collaboration with N. C. Hurst, C. J. Baker, and C. M. Surko. This work is supported by U.S. DTRA and the U.S. DOE/NSF plasma partnership.

  7. Testing the Model of Oscillating Magnetic Traps

    NASA Astrophysics Data System (ADS)

    Szaforz, Ż.; Tomczak, M.

    2015-01-01

    The aim of this paper is to test the model of oscillating magnetic traps (the OMT model), proposed by Jakimiec and Tomczak ( Solar Phys. 261, 233, 2010). This model describes the process of excitation of quasi-periodic pulsations (QPPs) observed during solar flares. In the OMT model energetic electrons are accelerated within a triangular, cusp-like structure situated between the reconnection point and the top of a flare loop as seen in soft X-rays. We analyzed QPPs in hard X-ray light curves for 23 flares as observed by Yohkoh. Three independent methods were used. We also used hard X-ray images to localize magnetic traps and soft X-ray images to diagnose thermal plasmas inside the traps. We found that the majority of the observed pulsation periods correlates with the diameters of oscillating magnetic traps, as was predicted by the OMT model. We also found that the electron number density of plasma inside the magnetic traps in the time of pulsation disappearance is strongly connected with the pulsation period. We conclude that the observations are consistent with the predictions of the OMT model for the analyzed set of flares.

  8. Filter vapor trap

    DOEpatents

    Guon, Jerold

    1976-04-13

    A sintered filter trap is adapted for insertion in a gas stream of sodium vapor to condense and deposit sodium thereon. The filter is heated and operated above the melting temperature of sodium, resulting in a more efficient means to remove sodium particulates from the effluent inert gas emanating from the surface of a liquid sodium pool. Preferably the filter leaves are precoated with a natrophobic coating such as tetracosane.

  9. Effect of interface and bulk traps on the C-V characterization of a LPCVD-SiNx/AlGaN/GaN metal-insulator-semiconductor structure

    NASA Astrophysics Data System (ADS)

    Bao, Qilong; Huang, Sen; Wang, Xinhua; Wei, Ke; Zheng, Yingkui; Li, Yankui; Yang, Chengyue; Jiang, Haojie; Li, Junfeng; Hu, Anqi; Yang, Xuelin; Shen, Bo; Liu, Xinyu; Zhao, Chao

    2016-06-01

    Silicon nitride (SiNx) film grown by low-pressure chemical vapor deposition (LPCVD) is utilized as a gate dielectric for AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs). Trap distribution at the gate-dielectric/III-nitrides interface is characterized by a temperature-dependent ac-capacitance technique. The extracted interface state density D it decreases from 2.92 × 1013 to 1.59 × 1012 cm-2 eV-1 as the energy level depth (E C-E T) increases from 0.29 to 0.50 eV, and then levels off to E C-E T = 0.80 eV. Capacitance-mode deep level transient spectroscopy (C-DLTS) and energy band diagram simulations reveal that deep levels with E C-E T > 0. 83 eV are responsible for the dispersion of capacitances at high temperature (>125 °C) and low frequencies (<1 kHz). A high-resolution transmission electron microscope (TEM) reveals that re-oxidation of the RCA-treated AlGaN barrier surface may be responsible for the relatively high density of shallow states at the LPCVD-SiNx/III-nitride interface.

  10. Measuring sunscreen protection against solar-simulated radiation-induced structural radical damage to skin using ESR/spin trapping: development of an ex vivo test method.

    PubMed

    Haywood, Rachel; Volkov, Arsen; Andrady, Carima; Sayer, Robert

    2012-03-01

    The in vitro star system used for sunscreen UVA-testing is not an absolute measure of skin protection being a ratio of the total integrated UVA/UVB absorption. The in vivo persistent-pigment-darkening method requires human volunteers. We investigated the use of the ESR-detectable DMPO protein radical-adduct in solar-simulator-irradiated skin substitutes for sunscreen testing. Sunscreens SPF rated 20+ with UVA protection, reduced this adduct by 40-65% when applied at 2 mg/cm(2). SPF 15 Organic UVA-UVB (BMDBM-OMC) and TiO(2)-UVB filters and a novel UVA-TiO(2) filter reduced it by 21, 31 and 70% respectively. Conventional broad-spectrum sunscreens do not fully protect against protein radical-damage in skin due to possible visible-light contributions to damage or UVA-filter degradation. Anisotropic spectra of DMPO-trapped oxygen-centred radicals, proposed intermediates of lipid-oxidation, were detected in irradiated sunscreen and DMPO. Sunscreen protection might be improved by the consideration of visible-light protection and the design of filters to minimise radical leakage and lipid-oxidation.

  11. Shadowed off-axis production of Ge nanoparticles in Ar gas atmosphere by pulsed laser deposition: Morphological, structural and charge trapping properties

    NASA Astrophysics Data System (ADS)

    Martín-Sánchez, J.; Capan, I.; Chahboun, A.; Pinto, S. R. C.; Vieira, E. M. F.; Rolo, A. G.; Gomes, M. J. M.

    2013-09-01

    In this work, a novel customized shadowed off-axis deposition set-up is used to perform an original study of Ge nanoparticles (NPs) formation in an inert Ar gas atmosphere by pulsed laser deposition at room temperature varying systematically the background Ar gas pressure (Pbase(Ar)), target-substrate distance (d) and laser repetition rate (f). The influence of these parameters on the final NPs size distributions is investigated and a fairly uniform droplets-free and non-agglomerated NPs distribution with average height = 2.8 ± 0.6 nm is obtained for optimized experimental conditions (Pbase(Ar) = 1 mbar; d = 3 cm; f = 10 Hz) with a fine control in the NPs density (from 3.2 × 109 cm-2 to 1.1 × 1011 cm-2). The crystalline quality of as-deposited NPs investigations demonstrate a strong dependence with the Ar gas pressure and a crystalline to amorphous phase volume fraction χc > 50% is found for Pbase(Ar) = 2 mbar. The NPs functionality for charge trapping applications has been successfully demonstrated by capacitance-voltage (C-V) electrical measurements.

  12. Measuring sunscreen protection against solar-simulated radiation-induced structural radical damage to skin using ESR/spin trapping: development of an ex vivo test method.

    PubMed

    Haywood, Rachel; Volkov, Arsen; Andrady, Carima; Sayer, Robert

    2012-03-01

    The in vitro star system used for sunscreen UVA-testing is not an absolute measure of skin protection being a ratio of the total integrated UVA/UVB absorption. The in vivo persistent-pigment-darkening method requires human volunteers. We investigated the use of the ESR-detectable DMPO protein radical-adduct in solar-simulator-irradiated skin substitutes for sunscreen testing. Sunscreens SPF rated 20+ with UVA protection, reduced this adduct by 40-65% when applied at 2 mg/cm(2). SPF 15 Organic UVA-UVB (BMDBM-OMC) and TiO(2)-UVB filters and a novel UVA-TiO(2) filter reduced it by 21, 31 and 70% respectively. Conventional broad-spectrum sunscreens do not fully protect against protein radical-damage in skin due to possible visible-light contributions to damage or UVA-filter degradation. Anisotropic spectra of DMPO-trapped oxygen-centred radicals, proposed intermediates of lipid-oxidation, were detected in irradiated sunscreen and DMPO. Sunscreen protection might be improved by the consideration of visible-light protection and the design of filters to minimise radical leakage and lipid-oxidation. PMID:22236285

  13. Trapping particles using waveguide-coupled gold bowtie plasmonic tweezers.

    PubMed

    Lin, Pin-Tso; Chu, Heng-Yi; Lu, Tsan-Wen; Lee, Po-Tsung

    2014-12-21

    We propose and demonstrate a trapping configuration integrating coupled waveguides and gold bowtie structures to form near-field plasmonic tweezers. Compared with excitation from the top, waves coupled through the waveguide can excite specific bowties on the waveguide and trap particles precisely. Thus this scheme is more efficient and compact, and will assist the circuit design on a chip. With lightning rod and gap effects, the gold bowtie structures can generate highly concentrated resonant fields and induce trapping forces as strong as 652 pN W(-1) on particles with diameters as small as 20 nm. This trapping capability is investigated numerically and verified experimentally with observations of the transport, trapping, and release of particles in the system. PMID:25288366

  14. A Pneumatic Actuated Microfluidic Beads-Trapping Device

    SciTech Connect

    Shao, Guocheng; Cai, Ziliang; Wang, Jun; Wang, Wanjun; Lin, Yuehe

    2011-08-20

    The development of a polydimethylsiloxane (PDMS) microfluidic microbeads trapping device is reported in this paper. Besides fluid channels, the proposed device includes a pneumatic control chamber and a beads-trapping chamber with a filter array structure. The pneumatic flow control chamber and the beads-trapping chamber are vertically stacked and separated by a thin membrane. By adjusting the pressure in the pneumatic control chamber, the membrane can either be pushed against the filter array to set the device in trapping mode or be released to set the device in releasing mode. In this paper, a computational fluid dynamics simulation was conducted to optimize the geometry design of the filter array structure; the device fabrication was also carried out. The prototype device was tested and the preliminary experimental results showed that it can be used as a beads-trapping unit for various biochemistry and analytical chemistry applications, especially for flow injection analysis systems.

  15. Al2O3 influence on structural, elastic, thermal properties of Yb(3+) doped Ba-La-tellurite glass: evidence of reduction in self-radiation trapping at 1μm emission.

    PubMed

    Balaji, S; Biswas, K; Sontakke, A D; Gupta, G; Ghosh, D; Annapurna, K

    2014-12-10

    Ba-La-tellurite glasses doped with Yb(3+) ions have been prepared through melt quenching technique by modifying their composition with the inclusion of varied concentration of Al2O3 to elucidate its effects on glass structural, elastic, thermal properties and Yb(3+) ion NIR luminescence performance. The FTIR spectral analysis indicates Al2O3 addition is promoting the conversion of BOs from NBOs which have been generated during the process of depolymerisation of main glass forming TeO4 units. The elastic properties of the glass revealed an improved rigidity of the glass network on addition of Al2O3. In concurrence to this, differential thermal analysis showed an increase in glass transition temperature with improved thermal stability factor. Also, Yb(3+) fluorescence dynamics demonstrated that, Al2O3 inclusion helps in restraining the detrimental radiation trapping of ∼1μm emission.

  16. Magnetic trap for thulium atoms

    SciTech Connect

    Sukachev, D D; Sokolov, A V; Chebakov, K A; Akimov, A V; Kolachevskii, N N; Sorokin, Vadim N

    2011-08-31

    For the first time ultra-cold thulium atoms were trapped in a magnetic quadrupole trap with a small field gradient (20 Gs cm{sup -1}). The atoms were loaded from a cloud containing 4x10{sup 5} atoms that were preliminarily cooled in a magneto-optical trap to the sub-Doppler temperature of 80 {mu}K. As many as 4x10{sup 4} atoms were trapped in the magnetic trap at the temperature of 40 {mu}K. By the character of trap population decay the lifetime of atoms was determined (0.5 s) and an upper estimate was obtained for the rate constant of inelastic binary collisions for spin-polarised thulium atoms in the ground state (g{sub in} < 10{sup -11}cm{sup 3} s{sup -1}). (magnetic traps)

  17. K{sup {pi}}=8{sup -} isomers and K{sup {pi}}=2{sup -} octupole vibrations in N=150 shell-stabilized isotones

    SciTech Connect

    Robinson, A. P.; Khoo, T. L.; Ahmad, I.; Kondev, F. G.; Seweryniak, D.; Back, B. B.; Carpenter, M. P.; Davids, C. N.; Greene, J. P.; Gros, S.; Janssens, R. V. F.; Lauritsen, T.; Lister, C. J.; Peterson, D.; Zhu, S.; Tandel, S. K.; Chowdhury, P.; Tandel, U. S.; Nakatsukasa, T.; Asai, M.

    2008-09-15

    Isomers have been populated in {sup 246}Cm and {sup 252}No with quantum numbers K{sup {pi}}=8{sup -}, which decay through K{sup {pi}}=2{sup -} rotational bands built on octupole vibrational states. For N=150 isotones with (even) atomic number Z=94-102, the K{sup {pi}}=8{sup -} and 2{sup -} states have remarkably stable energies, indicating neutron excitations. An exception is a singular minimum in the 2{sup -} energy at Z=98, due to the additional role of proton configurations. The nearly constant energies, in isotones spanning an 18% increase in Coulomb energy near the Coulomb limit, provide a test for theory. The two-quasiparticle K{sup {pi}}=8{sup -} energies are described with single-particle energies given by the Woods-Saxon potential and the K{sup {pi}}=2{sup -} vibrational energies by quasiparticle random-phase approximation calculations. Ramifications for self-consistent mean-field theory are discussed.

  18. Selective plasmonic trapping in periodic gold polygon tetramers

    NASA Astrophysics Data System (ADS)

    Xie, Jiao; Wang, Li; Liao, Zhongwei; Huang, Yingzhou; Li, Shunbo; Wang, Shuxia; Wen, Weijia

    2014-11-01

    Highly bounding light at metal surface by localized surface plasmon resonance (LSPR) improves the optical trapping of nanoparticles, which is called plasmonic trapping. Since LSPR is high related to the geometry of metal structures, the construction of metal nanostructure is extremely significant in the nano-trapping. In this work, the plasmonic trapping of dielectric nanoparticles in periodic gold polygon tetramers is investigated through finite-difference time-domain (FDTD) method. The simulation results of electric field distribution and the corresponding optical force indicate the number of side is quite important to the trapping efficiency that the square tetramers is obviously superior to other ones with more sides. However, this efficiency difference is also related to the size of nanoparticle that it is more sensitive to the smaller nanoparticles. Furthermore, the results also figure out not only trapping efficiency but also the trapping position is greatly influenced by the wavelength of trapping light in the same gold polygon tetramers. All our results open a way to selectively trap nanoparticles with required size at appointed positions, which has extensive application prospects in manipulation of nanoparticles in solution.

  19. Near-yrast structure of {sup 149}Pr

    SciTech Connect

    Rzaca-Urban, T.; Urban, W.; Pinston, J. A.; Simpson, G. S.; Ahmad, I.

    2010-12-15

    The neutron-rich nucleus {sup 149}Pr has been studied by means of prompt and delayed {gamma}-ray spectroscopy using the EUROGAM2 and Gammasphere arrays of Ge detectors. New spins have been assigned to a previously reported band and it is interpreted as having a h{sub 11/2} proton structure, from a comparison with quasiparticle-rotor model calculations. The strength of octupole correlations in odd-Z nuclei of the region is discussed.

  20. Experiments with trapped hydrogen atoms and neutrons

    NASA Astrophysics Data System (ADS)

    Ramsey, Norman F.

    1995-01-01

    The earliest trapped atom coherent resonance experiments were with material traps or bottles. In the atomic hydrogen maser the atoms are trapped inside a teflon-coated quartz bulb for about a second. Neutrons have been trapped for hundreds of seconds in suitably coated bottles or in superconducting magnetic traps. Results from experiments with trapped atoms and neutrons are given.

  1. Experiments with trapped hydrogen atoms and neutrons

    NASA Astrophysics Data System (ADS)

    Ramsey, Norman F.

    1993-03-01

    The earliest trapped atom coherent resonance experiments were with material traps or bottles. In the atomic hydrogen maser, the atoms are trapped inside a teflon-coated quartz bulb for about a second. Neutrons have been trapped for hundreds of seconds in suitably coated bottles or in superconducting magnetic traps. Results from experiments with trapped atoms and neutrons are reported.

  2. Cenozoic diapiric traps in eastern China

    SciTech Connect

    Xie-Pei, W.; Qi, F.; Jia-Hua, Z.

    1985-12-01

    Diapiric traps, including diapirs of salt and mud or igneous intrusives, have recently been found in many places in the Cenozoic petroliferous basins in eastern China, and most of them produce oil and gas. During the Eocene-early Oligocene, salt-lake basins evolved extensively. Plastic source materials for diapirism were deposited in the basins in great thickness. We have found that the diapiric traps of salt and mud in eastern China are unpierced or slightly pierced structures. The diapiric materials are a mixture of salt, gypsum, and mudstone, but mudstone is the main component of the plastic bodies. Based on an analysis of the structural features of the diapirs and the regional tectonic setting, we believe that the diapiric traps are caused by a combination of horizontal stress due to regional tectonic movement and vertical stress due to gravitational instability. Some diabase diapirs are arranged in a series of small anticlinal traps along the regional faults in the Subei basin of Jiangsu province. Oil and gas have been found in certain of these diapirs. 16 figures.

  3. Microtrap on a concave grating reflector for atom trapping

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Li, Tao; Yin, Ya-Ling; Li, Xing-Jia; Xia, Yong; Yin, Jian-Ping

    2016-08-01

    We propose a novel scheme of optical confinement for atoms by using a concave grating reflector. The two-dimension grating structure with a concave surface shape exhibits strong focusing ability under radially polarized illumination. Especially, the light intensity at the focal point is about 100 times higher than that of the incident light. Such a focusing optical field reflected from the curved grating structure can provide a deep potential to trap cold atoms. We discuss the feasibility of the structure serving as an optical dipole trap. Our results are as follows. (i) Van der Waals attraction potential to the surface of the structure has a low effect on trapped atoms. (ii) The maximum trapping potential is ∼ 1.14 mK in the optical trap, which is high enough to trap cold 87Rb atoms from a standard magneto-optical trap with a temperature of 120 μK, and the maximum photon scattering rate is lower than 1/s. (iii) Such a microtrap array can also manipulate and control cold molecules, or microscopic particles. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374100, 91536218, and 11274114) and the Natural Science Foundation of Shanghai Municipality, China (Grant No. 13ZR1412800).

  4. Microtrap on a concave grating reflector for atom trapping

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Li, Tao; Yin, Ya-Ling; Li, Xing-Jia; Xia, Yong; Yin, Jian-Ping

    2016-08-01

    We propose a novel scheme of optical confinement for atoms by using a concave grating reflector. The two-dimension grating structure with a concave surface shape exhibits strong focusing ability under radially polarized illumination. Especially, the light intensity at the focal point is about 100 times higher than that of the incident light. Such a focusing optical field reflected from the curved grating structure can provide a deep potential to trap cold atoms. We discuss the feasibility of the structure serving as an optical dipole trap. Our results are as follows. (i) Van der Waals attraction potential to the surface of the structure has a low effect on trapped atoms. (ii) The maximum trapping potential is ˜ 1.14 mK in the optical trap, which is high enough to trap cold 87Rb atoms from a standard magneto-optical trap with a temperature of 120 μK, and the maximum photon scattering rate is lower than 1/s. (iii) Such a microtrap array can also manipulate and control cold molecules, or microscopic particles. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374100, 91536218, and 11274114) and the Natural Science Foundation of Shanghai Municipality, China (Grant No. 13ZR1412800).

  5. The trapped mercury ion frequency standard

    NASA Technical Reports Server (NTRS)

    Mcguire, M. D.

    1977-01-01

    Singly ionized mercury atoms have a structure similar to neutral alkali atoms. They can be maintained as ions for very long times in an RF quadrupole ion trap. Thus, their ground state hyperfine structure can be used to make a frequency standard using optical pumping techniques similar to the well-known rubidium standard. The mass 199 isotope of mercury has an ionic hyperfine structure of 40.5 GHz. In a trap system a linewidth of 10 Hz has been measured. An expression is presented for the short-term stability of a proposed mercury standard as set by the achieved signal to noise ratio. There is prospect of further improvement. Long-term stability is affected by second order doppler effect, and by pressure, light, and Stark shifts. However, these appear either sufficiently small or sufficiently controlable that the proposed mercury ion standard would be competitive with existing standards.

  6. Atom trap trace analysis

    SciTech Connect

    Lu, Z.-T.; Bailey, K.; Chen, C.-Y.; Du, X.; Li, Y.-M.; O'Connor, T. P.; Young, L.

    2000-05-25

    A new method of ultrasensitive trace-isotope analysis has been developed based upon the technique of laser manipulation of neutral atoms. It has been used to count individual {sup 85}Kr and {sup 81}Kr atoms present in a natural krypton sample with isotopic abundances in the range of 10{sup {minus}11} and 10{sup {minus}13}, respectively. The atom counts are free of contamination from other isotopes, elements,or molecules. The method is applicable to other trace-isotopes that can be efficiently captured with a magneto-optical trap, and has a broad range of potential applications.

  7. Cenozoic diapiric traps in eastern China

    SciTech Connect

    Qi, F.; Xie-Pei, W.; Jia-Hua, Z.

    1984-04-01

    Genetically, there are 2 types of Cenozoic diapiric traps in the oil fields in eastern China. One type is produced by cold diapirism owing to the rise of evaporites and soft mudstone. This type can be divided into 3 patterns. The first pattern is the faulted ridge with 1000 m (3300 ft) closure and flanks dipping up to 30/sup 0/. A complex graben system is developed on the top. The amplitude of the core of the anticline is about 3000 m (9800 ft). The Xiangzheng structure in the Shengli oil field and the Wang-atcung structure in the Qian-jiang depression are examples. The second pattern is the gentle anticline or dome with 50-300 m (160-985 ft) closure and 3/sup 0/-10/sup 0/ dip on the flanks. The incompetent strata beneath it are about 1000 m (3300 ft) thick. The Tuocung-Shengli structure in the Shengli oil field is an example. The third pattern is a nose-like structure with less than 50 m (160 ft) closure. This pattern is usually located near the zero edge of incompetent strata. The Serniusi structure in the Dagang oil field is an example. Another type of Cenozoic diapiric trap results from hot diapirism associated with the intrusion of gabbro or diabase. Such traps are typically small, round domes. The dip of the flanking strata generally increases with depth as the diapir is approached. A graben system is developed on top of the diapir. The distribution of these traps is related usually to regional fault zones and coincides with the distribution of the magmatism. The Matouzung structure in the Jinhu depression is one of the examples.

  8. Cenozoic diapiric traps in eastern China

    SciTech Connect

    Qi, F.; Xie-Pei, W.; Jia-Hua, Z.

    1984-04-01

    Genetically, there are 2 types of Cenozoic diapiric traps in the oil fields in eastern China. One type is produced by cold diapirism owing to the rise of evaporites and soft mudstone. This type can be divided into 3 patterns. The first pattern is the faulted ridge with 1000 m (3300 ft) closure and flanks dipping up to 30/sup 0/. A complex graben system is developed on the top. The amplitude of the core of the anticline is about 3000 m (9800 ft). The Xiangzheng structure in the Shengli oil field and the Wang-cung structure in the Qian-jiang depression are examples. The second pattern is the gentle anticline or dome with 50-300 m (160-985 ft) closure and 3/sup 0/-10/sup 0/ dip on the flanks. The incompetent strata beneath it are about 1000 m (3300 ft) thick. The Tuocung-Shengli structure in the Shengli oil field is an example. The third pattern is a nose-like structure with less than 50 m (160 ft) closure. This pattern is usually located near the zero edge of incompetent strata. The Serniusi structure in the Dagang oil field is an example. Another type of Cenozoic diapiric trap results from hot diapirism associated with the intrusion of gabbro or diabase. Such traps are typically small, round domes. The dip of the flanking strata generally increases with depth as the diapir is approached. A graben system is developed on top of the diapir. The distribution of these traps is related usually to regional fault zones and coincides with the distribution of the magmatism. The Matouzung structure in the Jinhu depression is one of the examples.

  9. Computer simulations of ions in radio-frequency traps

    NASA Technical Reports Server (NTRS)

    Williams, A.; Prestage, J. D.; Maleki, L.; Djomehri, J.; Harabetian, E.

    1990-01-01

    The motion of ions in a trapped-ion frequency standard affects the stability of the standard. In order to study the motion and structures of large ion clouds in a radio-frequency (RF) trap, a computer simulation of the system that incorporates the effect of thermal excitation of the ions was developed. Results are presented from the simulation for cloud sizes up to 512 ions, emphasizing cloud structures in the low-temperature regime.

  10. Finite element simulations of hydrodynamic trapping in microfluidic particle-trap array systems

    PubMed Central

    Xu, Xiaoxiao; Li, Zhenyu; Nehorai, Arye

    2013-01-01

    Computational fluid dynamic (CFD) simulation is a powerful tool in the design and implementation of microfluidic systems, especially for systems that involve hydrodynamic behavior of objects such as functionalized microspheres, biological cells, or biopolymers in complex structures. In this work, we investigate hydrodynamic trapping of microspheres in a novel microfluidic particle-trap array device by finite element simulations. The accuracy of the time-dependent simulation of a microsphere's motion towards the traps is validated by our experimental results. Based on the simulation, we study the fluid velocity field, pressure field, and force and stress on the microsphere in the device. We further explore the trap array's geometric parameters and critical fluid velocity, which affect the microsphere's hydrodynamic trapping. The information is valuable for designing microfluidic devices and guiding experimental operation. Besides, we provide guidelines on the simulation set-up and release an openly available implementation of our simulation in one of the popular FEM softwares, COMSOL Multiphysics. Researchers may tailor the model to simulate similar microfluidic systems that may accommodate a variety of structured particles. Therefore, the simulation will be of particular interest to biomedical research involving cell or bead transport and migration, blood flow within microvessels, and drug delivery. PMID:24404071

  11. Spectroscopy of trapped francium

    NASA Astrophysics Data System (ADS)

    Grossman, Joshua Matus

    Atomic francium, which has no stable isotopes, is an attractive candidate for measurements of parity non-conservation. A heavy ion fusion reaction produces Fr at the Stony Brook superconducting LINAC, and we confine about 10,000 atoms in a magneto-optical trap (MOT). We made precise measurements (300 ppm) of the hyperfine splitting of the 7P1/2 state. Combining these measurements with previous measurements of the ground state hyperfine splitting, enabled us to extract the hyperfine anomaly in these states, and thus probe the nuclear magnetization. We located the previously unobserved 7D states and measured their energies and hyperfine splittings. Using time-correlated single-photon counting, we measured radiative lifetimes of 73.6 +/- 0.3 ns for the 7D3/2 level and 67.7 +/- 2.9 ns for the 7D5/2 level. We have constructed a new apparatus for efficient trapping of Fr in preparation for a measurement of the nuclear anapole moment.

  12. ATRAP - Progress Towards Trapped Antihydrogen

    SciTech Connect

    Grzonka, D.; Goldenbaum, F.; Oelert, W.; Sefzick, T.; Zhang, Z.; Comeau, D.; Hessels, E.A.; Storry, C.H.; Gabrielse, G.; Larochelle, P.; Lesage, D.; Levitt, B.; Speck, A.; Haensch, T.W.

    2005-10-26

    The ATRAP experiment at the CERN antiproton decelerator AD aims for a test of the CPT invariance by a high precision comparison of the 1s-2s transition in the hydrogen and the antihydrogen atom.Antihydrogen production is routinely operated at ATRAP and detailed studies have been performed in order to optimize the production efficiency of useful antihydrogen.For high precision measurements of atomic transitions cold antihydrogen in the ground state is required which must be trapped due to the low number of available antihydrogen atoms compared to the cold hydrogen beam used for hydrogen spectroscopy. To ensure a reasonable antihydrogen trapping efficiency a magnetic trap has to be superposed the nested Penning trap. First trapping tests of charged particles within a combined magnetic/Penning trap have started at ATRAP.

  13. Modulating TRAP-mediated transcription termination by AT during transcription of the leader region of the Bacillus subtilis trp operon.

    PubMed

    Sharma, Shraddha; Gollnick, Paul

    2014-05-01

    An 11-subunit protein called trp RNA binding Attenuation Protein (TRAP) controls attenuation of the tryptophan biosynthetic (trpEDCFBA) operon in Bacillus subtilis. Tryptophan-activated TRAP binds to 11 (G/U)AG repeats in the 5' leader region of trp mRNAs, and downregulates expression of the operon by promoting transcription termination prior to the structural genes. Anti-TRAP (AT) is an antagonist that binds to tryptophan-activated TRAP and prevents TRAP from binding to RNA, thereby upregulating expression of the trp genes. AT forms trimers, and multiple trimers bind to a TRAP 11mer. It is not known how many trimers must bind to TRAP in order to interfere with RNA binding. Studies of isolated TRAP and AT showed that AT can prevent TRAP from binding to the trp leader RNA but cannot dissociate a pre-formed TRAP-RNA complex. Here, we show that AT can prevent TRAP-mediated termination of transcription by inducing dissociation of TRAP from the nascent RNA when it has bound to fewer than all 11 (G/U)AG repeats. The 5'-most region of the TRAP binding site in the nascent transcript is most susceptible to dissociation from TRAP. We also show that one AT trimer bound to TRAP 11mer reduces the affinity of TRAP for RNA and eliminates TRAP-mediated transcription termination in vitro. PMID:24682818

  14. Structure of 2C-Methyl-D-erythritol-2,4-cyclodiphosphate Synthase from Shewanella oneidensis at 1.6 angstrom: Identification of Farnesyl pyrophosphate Trapped in a Hydrophobic Cavity

    SciTech Connect

    Ni, Shuisong; Robinson, Howard; Marsing, Gregory C.; Bussiere, Dirksen E.; Kennedy, Michael A.

    2004-11-01

    1. Introduction Enzymes in the non-mevalonate pathway for isoprenoid synthesis have gained recent attention because of their potential value as targets for antibiotic drug development. 2C-methyl-D-erythritol-2,4 cyclophosphate (MECDP) synthase is the fifth enzyme in the seven enzyme non-mevalonate pathway for synthesis of isopentenyl diphosphate. Four groups have published structures of MECDP synthase at resolutions varying from 1.6Å to 2.8Å, either in the presence or absence of substrate from Escherichia coli (Richard et al., 2002; Kemp et al., 2002; Steinbacher et al., 2002) or from Thermus thermophilus (Kishida et al., 2003). Among these structures, the protein always exists as a homotrimer either with a crystallographic or a non-crystallographic three-fold symmetry axis and an active site formed in a cleft between adjacent monomers. While the overall shape of the proteins is highly similar among these structures, each of the four reported structures contain different combinations of metal ions in the active site including a Zn2+ ion only (Steinbacher et al., 2002), a Mn2+ ion only (Richard et al., 2002), Zn2+ and Mn2+ ions (Kemp et al., 2002) or two Mg2+ ions (Kishida et al., 2003). Furthermore, two of the structures are reported to contain a hydrophobic channel along the three-fold symmetry axis that is capped by a cluster of three arginine side chains (one from each monomer) at one end of the cavity and a cluster of three glutamic acid side chains (one from each monomer) at the other side of the cavity. In a 1.8Å resolution structure, Kemp et al. (2002) reported a sulfate ion coordinated to the arginine cap and solvent trapped in a hydrophobic cavity. In a lower 2.8Å resolution structure, Richard et al. (2002) concluded that geranyl diphosphate, GPP, was most likely trapped by the arginine cap and hydrophobic cavity (Richard et al., 2002), however, the low resolution of the data together with the presence of the crystallographic symmetry axis prohibited a

  15. Gated charged-particle trap

    DOEpatents

    Benner, W. Henry

    1999-01-01

    The design and operation of a new type of charged-particle trap provides simultaneous measurements of mass, charge, and velocity of large electrospray ions. The trap consists of a detector tube mounted between two sets of center-bored trapping plates. Voltages applied to the trapping plates define symmetrically-opposing potential valleys which guide axially-injected ions to cycle back and forth through the charge-detection tube. A low noise charge-sensitive amplifier, connected to the tube, reproduces the image charge of individual ions as they pass through the detector tube. Ion mass is calculated from measurement of ion charge and velocity following each passage through the detector.

  16. DNA Separation Using Photoelectrophoretic Traps

    SciTech Connect

    Braiman, Avital; Thundat, Thomas George; Rudakov, Fedor M

    2011-01-01

    In our recent publications we presented a design that allows formation of highly localized and optically controlled electrophoretic traps. 1,2 We demonstrated that electrophoretic traps can be utilized for biomolecule photoconcentration, optically directed transport, and separation by size. 1,2 In the current publication we suggest a hybrid design for biomolecule separation which implements electrophoretic traps in tandem with well-established electrophoretic techniques. We perform Monte Carlo simulations that demonstrate that the resolution of well-established electrophoretic techniques can be greatly enhanced by introducing photoelectrophoretic traps.

  17. Trapped-electron runaway effect

    NASA Astrophysics Data System (ADS)

    Nilsson, E.; Decker, J.; Fisch, N. J.; Peysson, Y.

    2015-08-01

    In a tokamak, trapped electrons subject to a strong electric field cannot run away immediately, because their parallel velocity does not increase over a bounce period. However, they do pinch toward the tokamak center. As they pinch toward the center, the trapping cone becomes more narrow, so eventually they can be detrapped and run away. When they run away, trapped electrons will have a very different signature from circulating electrons subject to the Dreicer mechanism. The characteristics of what are called trapped-electron runaways are identified and quantified, including their distinguishable perpendicular velocity spectrum and radial extent.

  18. The crystal structure of Erwinia amylovora levansucrase provides a snapshot of the products of sucrose hydrolysis trapped into the active site.

    PubMed

    Wuerges, Jochen; Caputi, Lorenzo; Cianci, Michele; Boivin, Stephane; Meijers, Rob; Benini, Stefano

    2015-09-01

    Levansucrases are members of the glycoside hydrolase family and catalyse both the hydrolysis of the substrate sucrose and the transfer of fructosyl units to acceptor molecules. In the presence of sufficient sucrose, this may either lead to the production of fructooligosaccharides or fructose polymers. Aim of this study is to rationalise the differences in the polymerisation properties of bacterial levansucrases and in particular to identify structural features that determine different product spectrum in the levansucrase of the Gram-negative bacterium Erwinia amylovora (Ea Lsc, EC 2.4.1.10) as compared to Gram-positive bacteria such as Bacillus subtilis levansucrase. Ea is an enterobacterial pathogen responsible for the Fire Blight disease in rosaceous plants (e.g., apple and pear) with considerable interest for the agricultural industry. The crystal structure of Ea Lsc was solved at 2.77 Å resolution and compared to those of other fructosyltransferases from Gram-positive and Gram-negative bacteria. We propose the structural features, determining the different reaction products, to reside in just a few loops at the rim of the active site funnel. Moreover we propose that loop 8 may have a role in product length determination in Gluconacetobacter diazotrophicus LsdA and Microbacterium saccharophilum FFase. The Ea Lsc structure shows for the first time the products of sucrose hydrolysis still bound in the active site. PMID:26208466

  19. The crystal structure of Erwinia amylovora levansucrase provides a snapshot of the products of sucrose hydrolysis trapped into the active site.

    PubMed

    Wuerges, Jochen; Caputi, Lorenzo; Cianci, Michele; Boivin, Stephane; Meijers, Rob; Benini, Stefano

    2015-09-01

    Levansucrases are members of the glycoside hydrolase family and catalyse both the hydrolysis of the substrate sucrose and the transfer of fructosyl units to acceptor molecules. In the presence of sufficient sucrose, this may either lead to the production of fructooligosaccharides or fructose polymers. Aim of this study is to rationalise the differences in the polymerisation properties of bacterial levansucrases and in particular to identify structural features that determine different product spectrum in the levansucrase of the Gram-negative bacterium Erwinia amylovora (Ea Lsc, EC 2.4.1.10) as compared to Gram-positive bacteria such as Bacillus subtilis levansucrase. Ea is an enterobacterial pathogen responsible for the Fire Blight disease in rosaceous plants (e.g., apple and pear) with considerable interest for the agricultural industry. The crystal structure of Ea Lsc was solved at 2.77 Å resolution and compared to those of other fructosyltransferases from Gram-positive and Gram-negative bacteria. We propose the structural features, determining the different reaction products, to reside in just a few loops at the rim of the active site funnel. Moreover we propose that loop 8 may have a role in product length determination in Gluconacetobacter diazotrophicus LsdA and Microbacterium saccharophilum FFase. The Ea Lsc structure shows for the first time the products of sucrose hydrolysis still bound in the active site.

  20. Traps and seals II. Stratigraphic/capillary traps

    SciTech Connect

    Foster, N.H.; Beaumont, E.A.

    1988-01-01

    This text is a reprint belonging to a series of reprint volumes which in turn are part of the Treatise of Petroleum Geology. This volume contains papers that describe different stratigraphically controlled trap types, the preservation of porosity, and the importance of capillarity in trapping hydrocarbons.

  1. 50 CFR 697.19 - Trap limits and trap tag requirements for vessels fishing with lobster traps.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... vessels fishing with lobster traps. 697.19 Section 697.19 Wildlife and Fisheries FISHERY CONSERVATION AND... requirements for vessels fishing with lobster traps. (a) Area 1 trap limits. The Area 1 trap limit is 800 traps. Federally permitted lobster fishing vessels shall not fish with, deploy in, possess in, or haul back...

  2. The anti-trp RNA-binding attenuation protein (Anti-TRAP), AT, recognizes the tryptophan-activated RNA binding domain of the TRAP regulatory protein.

    PubMed

    Valbuzzi, Angela; Gollnick, Paul; Babitzke, Paul; Yanofsky, Charles

    2002-03-22

    In Bacillus subtilis, the trp RNA-binding attenuation protein (TRAP) regulates expression of genes involved in tryptophan metabolism in response to the accumulation of l-tryptophan. Tryptophan-activated TRAP negatively regulates expression by binding to specific mRNA sequences and either promoting transcription termination or blocking translation initiation. Conversely, the accumulation of uncharged tRNA(Trp) induces synthesis of an anti-TRAP protein (AT), which forms a complex with TRAP and inhibits its activity. In this report, we investigate the structural features of TRAP required for AT recognition. A collection of TRAP mutant proteins was examined that were known to be partially or completely defective in tryptophan binding and/or RNA binding. Analyses of AT interactions with these proteins were performed using in vitro transcription termination assays and cross-linking experiments. We observed that TRAP mutant proteins that had lost the ability to bind RNA were no longer recognized by AT. Our findings suggest that AT acts by competing with messenger RNA for the RNA binding domain of TRAP. B. subtilis AT was also shown to interact with TRAP proteins from Bacillus halodurans and Bacillus stearothermophilus, implying that the structural elements required for AT recognition are conserved in the TRAP proteins of these species. Analyses of AT interaction with B. stearothermophilus TRAP at 60 degrees C demonstrated that AT is active at this elevated temperature. PMID:11786553

  3. Cryogenic ion trapping systems with surface-electrode traps.

    PubMed

    Antohi, P B; Schuster, D; Akselrod, G M; Labaziewicz, J; Ge, Y; Lin, Z; Bakr, W S; Chuang, I L

    2009-01-01

    We present two simple cryogenic rf ion trap systems in which cryogenic temperatures and ultra high vacuum pressures can be reached in as little as 12 h. The ion traps are operated either in a liquid helium bath cryostat or in a low vibration closed cycle cryostat. The fast turn around time and availability of buffer gas cooling made the systems ideal for testing surface-electrode ion traps. The vibration amplitude of the closed cycled cryostat was found to be below 106 nm. We evaluated the systems by loading surface-electrode ion traps with (88)Sr(+) ions using laser ablation, which is compatible with the cryogenic environment. Using Doppler cooling we observed small ion crystals in which optically resolved ions have a trapped lifetime over 2500 min.

  4. A Compact Structure of Cytochrome c Trapped in a Lysine-Ligated State: Loop Refolding and Functional Implications of a Conformational Switch.

    PubMed

    Amacher, Jeanine F; Zhong, Fangfang; Lisi, George P; Zhu, Michael Q; Alden, Stephanie L; Hoke, Kevin R; Madden, Dean R; Pletneva, Ekaterina V

    2015-07-01

    It has been suggested that the alkaline form of cytochrome c (cyt c) regulates function of this protein as an electron carrier in oxidative phosphorylation and as a peroxidase that reacts with cardiolipin (CL) during apoptosis. In this form, Met80, the native ligand to the heme iron, is replaced by a Lys. While it has become clear that the structure of cyt c changes, the extent and sequence of conformational rearrangements associated with this ligand replacement remain a subject of debate. Herein we report a high-resolution crystal structure of a Lys73-ligated cyt c conformation that reveals intricate change in the heme environment upon this switch in the heme iron ligation. The structure is surprisingly compact, and the heme coordination loop refolds into a β-hairpin with a turn formed by the highly conserved residues Pro76 and Gly77. Repositioning of residue 78 modifies the intraprotein hydrogen-bonding network and, together with adjustments of residues 52 and 74, increases the volume of the heme pocket to allow for insertion of one of the CL acyl moieties next to Asn52. Derivatization of Cys78 with maleimide creates a solution mimic of the Lys-ligated cyt c that has enhanced peroxidase activity, adding support for a role of the Lys-ligated cyt c in the apoptotic mechanism. Experiments with the heme peptide microperoxidase-8 and engineered model proteins provide a thermodynamic rationale for the switch to Lys ligation upon perturbations in the protein scaffold. PMID:26038984

  5. Solar energy trap

    NASA Technical Reports Server (NTRS)

    Brantley, L. W., Jr. (Inventor)

    1976-01-01

    An apparatus is described for trapping solar energy for heating a fluid that could be subsequently used in turbines and similar devices. The apparatus includes an elongated vertical light pipe having an open end through which the visible spectrum of electromagnetic radiation from the sun passes to strike a tubular absorber. The light pipe has a coated interior surface of a low absorptivity and a high reflectivity at the visible wavelengths and a high absorptivity/emissivity ratio at infrared wavelengths. The tubular absorber has a coating on the surface for absorbing visible wavelengths to heat the fluid passing through. Infrared wave lengths are radiated from the tubular absorber back into the light pipe for heating fluid passing through a tubular coil wound around it.

  6. Structural definition of trehalose 6-monomycolates and trehalose 6,6'-dimycolates from the pathogen Rhodococcus equi by multiple-stage linear ion-trap mass spectrometry with electrospray ionization.

    PubMed

    Hsu, Fong-Fu; Wohlmann, Jens; Turk, John; Haas, Albert

    2011-12-01

    The cell wall of the pathogenic bacterium Rhodococcus equi (R. equi) contains abundant trehalose monomycolate (TMM) and trehalose dimycolate (TDM), the glycolipids bearing mycolic acids. Here, we describe multiple-stage (MS(n)) linear ion-trap (LIT) mass spectrometric approaches toward structural characterization of TMM and TDM desorbed as [M + Alk](+) (Alk = Na, Li) and as [M + X](-) (X = CH(3)CO(2), HCO(2)) ions by electrospray ionization (ESI). Upon MS(n) (n=2, 3, 4) on the [M + Alk](+) or the [M + X](-) adduct ions of TMM and TDM, abundant structurally informative fragment ions are readily available, permitting fast assignment of the length of the meromycolate chain and of the α-branch on the mycolyl residues. In this way, structures of TMM and TDM isolated from pathogenic R. equi strain 103 can be determined. Our results indicate that the major TMM and TDM molecules possess 6, and/or 6'-mycolyl groups that consist of mainly C14 and C16 α-branches with meromycolate branches ranging from C18 to C28, similar to the structures of the unbound mycolic acids found in the cell envelope. Up to 60 isobaric isomers varying in chain length of the α-branch and of the meromycolate backbone were observed for some of the TDM species in the mixture. This mass spectrometric approach provides a direct method that affords identification of various TMM and TDM isomers in a mixture of which the complexity of this lipid class has not been previously reported using other analytical methods. PMID:21972013

  7. Zinc-oxide charge trapping memory cell with ultra-thin chromium-oxide trapping layer

    SciTech Connect

    El-Atab, Nazek; Rizk, Ayman; Nayfeh, Ammar; Okyay, Ali K.

    2013-11-15

    A functional zinc-oxide based SONOS memory cell with ultra-thin chromium oxide trapping layer was fabricated. A 5 nm CrO{sub 2} layer is deposited between Atomic Layer Deposition (ALD) steps. A threshold voltage (V{sub t}) shift of 2.6V was achieved with a 10V programming voltage. Also for a 2V V{sub t} shift, the memory with CrO{sub 2} layer has a low programming voltage of 7.2V. Moreover, the deep trapping levels in CrO{sub 2} layer allows for additional scaling of the tunnel oxide due to an increase in the retention time. In addition, the structure was simulated using Physics Based TCAD. The results of the simulation fit very well with the experimental results providing an understanding of the charge trapping and tunneling physics.

  8. Trap generation and occupation dynamics in SiO2 under charge injection stress

    NASA Astrophysics Data System (ADS)

    Nissan-Cohen, Y.; Shappir, J.; Frohman-Bentchkowsky, D.

    1986-09-01

    The effect of enduring charge injection on the physical properties of the SiO2 layer of a metal-oxide-semiconductor structure is studied by means of a novel characterization method. It is based on the observation reported previously, that under charge injection conditions the density of occupied oxide traps reaches a value which is only a fraction of the total trap density. This trap occupation level is strongly dependent on the oxide electric field. The oxide trap density can be evaluated by measuring this field dependence, using a relatively small amount of charge injection. This method is used to distinguish between the process of trap generation and electron trapping in the generated traps, under conditions of continuous charge injection up to levels of more than 50 C/cm2. The trap generation rate is found to be proportional to the flux of the injected charge, and to increase exponentially with the oxide electric field. At high oxide field only a small fraction of the newly generated traps are occupied; consequently, the measured oxide charge buildup does not reflect the actual increase in the density of generated traps. The density of the generated traps reaches high values of the order of 1020 cm-3. It is suggested that these high values of oxide traps may be the cause of the SiO2 ``wear out'' type breakdown, by forming a new path of conductance by electron tunneling between closely spaced generated traps.

  9. Quantum computing with trapped ions

    SciTech Connect

    Hughes, R.J.

    1998-01-01

    The significance of quantum computation for cryptography is discussed. Following a brief survey of the requirements for quantum computational hardware, an overview of the ion trap quantum computation project at Los Alamos is presented. The physical limitations to quantum computation with trapped ions are analyzed and an assessment of the computational potential of the technology is made.

  10. Nontoxic Antifreeze for Insect Traps

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Propylene glycol in water is a safe and effective alternative to ethylene glycol as a capture liquid in insect traps (pitfalls, flight intercepts, pan traps). Propylene glycol formulations are readily available because it is the primary (95%) ingredient in certain automotive antifreeze formulations...

  11. Trapped surfaces in spherical stars

    SciTech Connect

    Bizon, P.; Malec, E.; O'Murchadha, N.

    1988-09-05

    We give necessary and sufficient conditions for the existence of trapped surfaces in spherically symmetric spacetimes. These conditions show that the formation of trapped surfaces depends on both the degree of concentration and the average flow of the matter. The result can be considered as a partial validation of the cosmic-censorship hypothesis.

  12. Mass trapping for Anastrepha suspensa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mass trapping has been found to be highly effective for control of pest fruit flies when populations are low and a highly effective lure is available for the target species. Successful population control through mass trapping is an indicator that attract-and-kill bait stations may be equally succes...

  13. Intrinsic and extrinsic pinning in NdFeAs(O,F): vortex trapping and lock-in by the layered structure

    PubMed Central

    Tarantini, C.; Iida, K.; Hänisch, J.; Kurth, F.; Jaroszynski, J.; Sumiya, N.; Chihara, M.; Hatano, T.; Ikuta, H.; Schmidt, S.; Seidel, P.; Holzapfel, B.; Larbalestier, D. C.

    2016-01-01

    Fe-based superconductors (FBS) present a large variety of compounds whose properties are affected to different extents by their crystal structures. Amongst them, the REFeAs(O,F) (RE1111, RE being a rare-earth element) is the family with the highest critical temperature Tc but also with a large anisotropy and Josephson vortices as demonstrated in the flux-flow regime in Sm1111 (Tc ∼ 55 K). Here we focus on the pinning properties of the lower-Tc Nd1111 in the flux-creep regime. We demonstrate that for H//c critical current density Jc at high temperatures is dominated by point-defect pinning centres, whereas at low temperatures surface pinning by planar defects parallel to the c-axis and vortex shearing prevail. When the field approaches the ab-planes, two different regimes are observed at low temperatures as a consequence of the transition between 3D Abrikosov and 2D Josephson vortices: one is determined by the formation of a vortex-staircase structure and one by lock-in of vortices parallel to the layers. This is the first study on FBS showing this behaviour in the full temperature, field, and angular range and demonstrating that, despite the lower Tc and anisotropy of Nd1111 with respect to Sm1111, this compound is substantially affected by intrinsic pinning generating a strong ab-peak in Jc. PMID:27782196

  14. Optical Traps to Study Properties of Molecular Motors

    PubMed Central

    Spudich, James A.; Rice, Sarah E.; Rock, Ronald S.; Purcell, Thomas J.; Warrick, Hans M.

    2016-01-01

    In vitro motility assays enabled the analysis of coupling between ATP hydrolysis and movement of myosin along actin filaments or kinesin along microtubules. Single-molecule assays using laser trapping have been used to obtain more detailed information about kinesins, myosins, and processive DNA enzymes. The combination of in vitro motility assays with laser-trap measurements has revealed detailed dynamic structural changes associated with the ATPase cycle. This article describes the use of optical traps to study processive and nonprocessive molecular motor proteins, focusing on the design of the instrument and the assays to characterize motility. PMID:22046048

  15. Universal, strong and long-ranged trapping by optical conveyors

    NASA Astrophysics Data System (ADS)

    Ruffner, David; Grier, David G.

    2015-03-01

    Optical conveyors are active tractor beams that selectively transport illuminated objects either upstream or downstream along their axes. Formed by the coherent superposition of coaxial Bessel beams, an optical conveyor features an axial array of equally spaced intensity maxima that act as optical traps for small objects. We demonstrate through measurements on colloidal spheres and numerical calculations based on the generalized Lorenz-Mie theory that optical conveyors' interferometric structure endows them with trapping characteristics far superior to those of conventional optical tweezers. Optical conveyors form substantially stiffer traps and can transport a wider variety of materials over a much longer axial range.

  16. Universal, strong and long-ranged trapping by optical conveyors.

    PubMed

    Ruffner, David B; Grier, David G

    2014-11-01

    Optical conveyors are active tractor beams that selectively transport illuminated objects either upstream or downstream along their axes. Formed by the coherent superposition of coaxial Bessel beams, an optical conveyor features an axial array of equally spaced intensity maxima that act as optical traps for small objects. We demonstrate through measurements on colloidal spheres and numerical calculations based on the generalized Lorenz-Mie theory that optical conveyors' interferometric structure endows them with trapping characteristics far superior to those of conventional optical tweezers. Optical conveyors form substantially stiffer traps and can transport a wider variety of materials over a much longer axial range. PMID:25401830

  17. Optical traps to study properties of molecular motors.

    PubMed

    Spudich, James A; Rice, Sarah E; Rock, Ronald S; Purcell, Thomas J; Warrick, Hans M

    2011-11-01

    In vitro motility assays enabled the analysis of coupling between ATP hydrolysis and movement of myosin along actin filaments or kinesin along microtubules. Single-molecule assays using laser trapping have been used to obtain more detailed information about kinesins, myosins, and processive DNA enzymes. The combination of in vitro motility assays with laser-trap measurements has revealed detailed dynamic structural changes associated with the ATPase cycle. This article describes the use of optical traps to study processive and nonprocessive molecular motor proteins, focusing on the design of the instrument and the assays to characterize motility.

  18. Calibration of optical traps by dual trapping of one bead

    NASA Astrophysics Data System (ADS)

    Dutov, Pavel; Schieber, Jay

    2014-03-01

    Optical trapping and tracking is a powerful method for many biological and rheological applications. Recent advances in microrheological techniques, like two-point microrheology, allow probing mechanical properties of viscoelastic networks with mesh size bigger than the size of the microbead itself, but require high signal to noise ratio. Noise level in the system can be reduced by removing active elements, like acousto-optical deflectors or galvo-mirrors from the optical train and making the trap fixed. We introduce a method for optical trap calibration that is suitable for viscoelastic material and allows calibration of a fixed trap. The method is designed for use on experimental setups with two optical tweezers and based on pulling a particle with one trap while simultaneously holding it with the other. No piezo-stage is needed and only one optical trap must be movable with galvo-mirrors, piezo-mirrors or acousto-optical deflectors. The method combines advantages of commonly known PSD-fitting and fast-sweeping methods, allowing calibration of a completely fixed trap in a fluid of unknown viscosity/viscoelasticity. We acknowledge financial support of DARPA grant W911NF-09-1-0378.

  19. Trapping phosphate anions inside the [Ag{sub 4}I]{sup 3+} framework: Structure, bonding, and properties of Ag{sub 4}I(PO{sub 4})

    SciTech Connect

    Oleneva, Olga S.; Kirsanova, Maria A.; Shestimerova, Tatiana A.; Abramchuk, Nikolay S.; Davliatshin, Dmitry I.; Bykov, Mikhail A.; Dikarev, Evgeny V.; Shevelkov, Andrei V.

    2008-01-15

    Orange-red Ag{sub 4}I(PO{sub 4}) crystallizes in the monoclinic system, space group P2{sub 1}/m (No. 11), with the unit cell dimensions a=9.0874(6) A, b=6.8809(5) A, c=11.1260(7) A, {beta}=109.450(1){sup o}, and Z=4. The crystal structure is fully ordered; it comprises the silver-iodine three-dimensional positively charged framework hosting the tetrahedral PO{sub 4}{sup 3-} guest anions. The framework features high coordination numbers for iodine and manifold Ag-Ag bonds ranging from 3.01 to 3.46 A. The Ag-Ag interaction is bonding, it involves silver 4d and 5s orbitals lying, together with the orbitals of iodine, just below the Fermi level. Though the orbitals of silver and iodine define the conducting properties of the title compound, the interaction between the framework and the guest anions is also important and is responsive to the number of the silver atoms surrounding the PO{sub 4}{sup 3-} tetrahedra. Ag{sub 4}I(PO{sub 4}) melts incongruently at 591 K and produces a mixture of the silver phosphate and an amorphous phase upon cooling. Pure Ag{sub 4}I(PO{sub 4}) is a poor conductor with a room temperature conductivity of 3x10{sup -6} S m{sup -1}. The discrepancies between the properties observed here and those reported previously in the literature are discussed. - Graphical abstract: Regular [PO{sub 4}] tetrahedra fill large voids in the Ag-I framework to form a host-guest compound, Ag{sub 4}I(PO{sub 4}). It has a perfectly ordered crystal structure, atypical for this kind of compounds, rendering the study of the manifold Ag-Ag bonds and the host-guest interaction. However, this ordering leads to low ionic conductivity.

  20. Pulsed filling of a dark magnetooptical trap for rubidium atoms

    SciTech Connect

    Chapovskii, Pavel L

    2006-03-31

    The parameters of a dark magnetooptical trap for rubidium atoms are measured. The rubidium atoms captured and cooled in the trap occupy a hyperfine level of the ground electronic state, which does not interact with cooling laser radiation. The pulsed filling of the trap is produced due to desorption of rubidium caused by irradiation by a short (1 ms) light pulse. The trap captures and cools 2.5x10{sup 8} rubidium atoms approximately for 0.2 s. The absorption spectra of a weak probe field by cold atoms are obtained, which demonstrate a good spectral resolution of the hyperfine structure in the excited state. This structure is completely hidden by the Doppler broadening in rubidium vapours at room temperature. (laser cooling)

  1. The trapped human experiment.

    PubMed

    Huo, R; Agapiou, A; Bocos-Bintintan, V; Brown, L J; Burns, C; Creaser, C S; Devenport, N A; Gao-Lau, B; Guallar-Hoyas, C; Hildebrand, L; Malkar, A; Martin, H J; Moll, V H; Patel, P; Ratiu, A; Reynolds, J C; Sielemann, S; Slodzynski, R; Statheropoulos, M; Turner, M A; Vautz, W; Wright, V E; Thomas, C L P

    2011-12-01

    This experiment observed the evolution of metabolite plumes from a human trapped in a simulation of a collapsed building. Ten participants took it in turns over five days to lie in a simulation of a collapsed building and eight of them completed the 6 h protocol while their breath, sweat and skin metabolites were passed through a simulation of a collapsed glass-clad reinforced-concrete building. Safety, welfare and environmental parameters were monitored continuously, and active adsorbent sampling for thermal desorption GC-MS, on-line and embedded CO, CO(2) and O(2) monitoring, aspirating ion mobility spectrometry with integrated semiconductor gas sensors, direct injection GC-ion mobility spectrometry, active sampling thermal desorption GC-differential mobility spectrometry and a prototype remote early detection system for survivor location were used to monitor the evolution of the metabolite plumes that were generated. Oxygen levels within the void simulator were allowed to fall no lower than 19.1% (v). Concurrent levels of carbon dioxide built up to an average level of 1.6% (v) in the breathing zone of the participants. Temperature, humidity, carbon dioxide levels and the physiological measurements were consistent with a reproducible methodology that enabled the metabolite plumes to be sampled and characterized from the different parts of the experiment. Welfare and safety data were satisfactory with pulse rates, blood pressures and oxygenation, all within levels consistent with healthy adults. Up to 12 in-test welfare assessments per participant and a six-week follow-up Stanford Acute Stress Response Questionnaire indicated that the researchers and participants did not experience any adverse effects from their involvement in the study. Preliminary observations confirmed that CO(2), NH(3) and acetone were effective markers for trapped humans, although interactions with water absorbed in building debris needed further study. An unexpected observation from the NH(3

  2. Nanoantennas for enhanced light trapping in transparent organic solar cells

    NASA Astrophysics Data System (ADS)

    Voroshilov, P. M.; Simovski, C. R.; Belov, P. A.

    2014-12-01

    We propose a light-trapping structure offering a significant enhancement of photovoltaic absorption in transparent organic solar cells operating at infrared, while the visible light transmission keeps sufficiently high. The main mechanism of light trapping is related with the excitation of collective oscillations of the metal nanoantenna arrays, characterized by advantageous field distribution in the volume of the solar cell. It allows more than triple increase in infrared photovoltaic absorption.

  3. Hyperfine spectra of trapped bosons in optical lattices

    SciTech Connect

    Hazzard, Kaden R. A.; Mueller, Erich J.

    2007-12-15

    We calculate the interaction induced inhomogeneous broadening of spectral lines in a trapped Bose gas as a function of the depth of a three-dimensional cubic optical lattice. As observed in recent experiments, we find that the terraced 'wedding-cake' structure of Mott plateaus splits the spectrum into a series of discrete peaks. The spectra are extremely sensitive to density corrugations and trap anharmonicities. For example, even when the majority of the cloud is superfluid the spectrum displays discrete peaks.

  4. 50 CFR 31.16 - Trapping program.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Disposal § 31.16 Trapping program. Except as hereafter noted, persons trapping animals on wildlife refuge... affecting land, water, vegetation, or wildlife populations. Each person trapping on any wildlife refuge...

  5. 50 CFR 31.16 - Trapping program.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Disposal § 31.16 Trapping program. Except as hereafter noted, persons trapping animals on wildlife refuge... affecting land, water, vegetation, or wildlife populations. Each person trapping on any wildlife refuge...

  6. 50 CFR 31.16 - Trapping program.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Disposal § 31.16 Trapping program. Except as hereafter noted, persons trapping animals on wildlife refuge... affecting land, water, vegetation, or wildlife populations. Each person trapping on any wildlife refuge...

  7. Trap-mulching Argentine ants.

    PubMed

    Silverman, Jules; Sorenson, Clyde E; Waldvogel, Michael G

    2006-10-01

    Argentine ant, Linepithema humile (Mayr), management is constrained, in large part, by polydomy where nestmates are distributed extensively across urban landscapes, particularly within mulch. Management with trap-mulching is a novel approach derived from trap-cropping where ants are repelled from a broad domain of nest sites to smaller defined areas, which are subsequently treated with insecticide. This concept was field-tested with mulch surrounding ornamental trees replaced with a narrow band of pine (Pinus spp.) needle mulch (trap) within a much larger patch of repellent aromatic cedar (Juniperus spp.) mulch. After ants reestablished around the trees, the pine needle mulch band was treated with 0.06% fipronil (Termidor). Poor results were obtained when the trap extended from the tree trunk to the edge of the mulched area. When the trap was applied as a circular band around the tree trunk reductions in the number of foraging ants were recorded through 14 d compared with an untreated mulch control, but not for longer periods. Reductions in the number of ant nests within mulch were no different between the trap mulch and any of the other treatments. We conclude that trap-mulching offers limited benefits, and that successful management of Argentine ants will require implementation of complementary or perhaps alternative strategies.

  8. Combined acoustic and optical trapping

    PubMed Central

    Thalhammer, G.; Steiger, R.; Meinschad, M.; Hill, M.; Bernet, S.; Ritsch-Marte, M.

    2011-01-01

    Combining several methods for contact free micro-manipulation of small particles such as cells or micro-organisms provides the advantages of each method in a single setup. Optical tweezers, which employ focused laser beams, offer very precise and selective handling of single particles. On the other hand, acoustic trapping with wavelengths of about 1 mm allows the simultaneous trapping of many, comparatively large particles. With conventional approaches it is difficult to fully employ the strengths of each method due to the different experimental requirements. Here we present the combined optical and acoustic trapping of motile micro-organisms in a microfluidic environment, utilizing optical macro-tweezers, which offer a large field of view and working distance of several millimeters and therefore match the typical range of acoustic trapping. We characterize the acoustic trapping forces with the help of optically trapped particles and present several applications of the combined optical and acoustic trapping, such as manipulation of large (75 μm) particles and active particle sorting. PMID:22025990

  9. Nanoscale ablation through optically trapped microspheres

    NASA Astrophysics Data System (ADS)

    Fardel, Romain; McLeod, Euan; Tsai, Yu-Cheng; Arnold, Craig B.

    2010-10-01

    The ability to directly create patterns with size scales below 100 nm is important for many applications where the production or repair of high resolution and density features is needed. Laser-based direct-write methods have the benefit of being able to quickly and easily modify and create structures on existing devices, but ablation can negatively impact the overall technique. In this paper we show that self-positioning of near-field objectives through the optical trap assisted nanopatterning (OTAN) method allows for ablation without harming the objective elements. Small microbeads are positioned in close proximity to a substrate where ablation is initiated. Upon ablation, these beads are temporarily displaced from the trap but rapidly return to the initial position. We analyze the range of fluence values for which this process occurs and find that there exists a critical threshold beyond which the beads are permanently ejected.

  10. Trapping tsetse flies on water

    PubMed Central

    Laveissière, C.; Camara, M.; Rayaisse, J.B.; Salou, E.; Kagbadouno, M.; Solano, P.

    2011-01-01

    Riverine tsetse flies such as Glossina palpalis gambiensis and G. tachinoides are the vectors of human and animal trypanosomoses in West Africa. Despite intimate links between tsetse and water, to our knowledge there has never been any attempt to design trapping devices that would catch tsetse on water. In mangrove (Guinea) one challenging issue is the tide, because height above the ground for a trap is a key factor affecting tsetse catches. The trap was mounted on the remains of an old wooden dugout, and attached with rope to nearby branches, thereby allowing it to rise and fall with the tide. Catches showed a very high density of 93.9 flies/”water-trap”/day, which was significantly higher (p < 0.05) than all the catches from other habitats where the classical trap had been used. In savannah, on the Comoe river of South Burkina Faso, the biconical trap was mounted on a small wooden raft anchored to a stone, and catches were compared with the classical biconical trap put on the shores. G. p. gambiensis and G. tachinoides densities were not significantly different from those from the classical biconical one. The adaptations described here have allowed to efficiently catch tsetse on the water, which to our knowledge is reported here for the first time. This represents a great progress and opens new opportunities to undertake studies on the vectors of trypanosomoses in mangrove areas of Guinea, which are currently the areas showing the highest prevalences of sleeping sickness in West Africa. It also has huge potential for tsetse control using insecticide impregnated traps in savannah areas where traps become less efficient in rainy season. The Guinean National control programme has already expressed its willingness to use such modified traps in its control campaigns in Guinea, as has the national PATTEC programme in Burkina Faso during rainy season. PMID:21678789

  11. Flexible, light trapping substrates for organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Park, Yoonseok; Berger, Jana; Tang, Zheng; Müller-Meskamp, Lars; Lasagni, Andrés Fabián; Vandewal, Koen; Leo, Karl

    2016-08-01

    Micro-structured organic photovoltaic (OPV) devices on polyethylene terephthalate substrates are produced using direct laser interference patterning (DLIP). The performance of organic solar cells on these substrates is improved by a factor of 1.16, and a power conversion efficiency of 7.70% is achieved. We show that a shorter spatial period of the pattern allows for a stronger light trapping effect in solar cell, as it leads to a longer light path. Moreover, since the patterned structures are located on the outside of the fully encapsulated OPV devices, there are no problems with the roughness induced shunts.

  12. Neutrophil Extracellular Traps Go Viral

    PubMed Central

    Schönrich, Günther; Raftery, Martin J.

    2016-01-01

    Neutrophils are the most numerous immune cells. Their importance as the first line of defense against bacterial and fungal pathogens is well described. In contrast, the role of neutrophils in controlling viral infections is less clear. Bacterial and fungal pathogens can stimulate neutrophils extracellular traps (NETs) in a process called NETosis. Although NETosis has previously been described as a special form of programmed cell death, there are forms of NET production that do not end with the demise of neutrophils. As an end result of NETosis, genomic DNA complexed with microbicidal proteins is expelled from neutrophils. These structures can kill pathogens or at least prevent their local spread within host tissue. On the other hand, disproportionate NET formation can cause local or systemic damage. Only recently, it was recognized that viruses can also induce NETosis. In this review, we discuss the mechanisms by which NETs are produced in the context of viral infection and how this may contribute to both antiviral immunity and immunopathology. Finally, we shed light on viral immune evasion mechanisms targeting NETs. PMID:27698656

  13. Neutrophil Extracellular Traps Go Viral

    PubMed Central

    Schönrich, Günther; Raftery, Martin J.

    2016-01-01

    Neutrophils are the most numerous immune cells. Their importance as the first line of defense against bacterial and fungal pathogens is well described. In contrast, the role of neutrophils in controlling viral infections is less clear. Bacterial and fungal pathogens can stimulate neutrophils extracellular traps (NETs) in a process called NETosis. Although NETosis has previously been described as a special form of programmed cell death, there are forms of NET production that do not end with the demise of neutrophils. As an end result of NETosis, genomic DNA complexed with microbicidal proteins is expelled from neutrophils. These structures can kill pathogens or at least prevent their local spread within host tissue. On the other hand, disproportionate NET formation can cause local or systemic damage. Only recently, it was recognized that viruses can also induce NETosis. In this review, we discuss the mechanisms by which NETs are produced in the context of viral infection and how this may contribute to both antiviral immunity and immunopathology. Finally, we shed light on viral immune evasion mechanisms targeting NETs.

  14. Interfacial charge trapping in the polymer solar cells and its elimination by solvent annealing

    NASA Astrophysics Data System (ADS)

    Chauhan, A. K.; Gusain, Abhay; Jha, P.; Veerender, P.; Koiry, S. P.; Sridevi, C.; Aswal, D. K.; Gupta, S. K.; Taguchi, D.; Manaka, T.; Iwamoto, M.

    2016-09-01

    The PCDTBT:PCBM solar cells were fabricated adopting a tandem layer approach to investigate the critical issues of charge trapping, radiation absorption, and efficiency in polymer solar cells. This layered structure was found to be a source of charge trapping which was identified and confirmed by impedance spectroscopy. The low efficiency in multilayered structures was related to trapping of photo-generated carriers and low carrier mobility, and thus an increased recombination. Solvent annealing of the structures in tetrahydrofuran vapors was found beneficial in homogenizing the active layer, dissolving additional interfaces, and elimination of charge traps which improved the carrier mobilities and eventually the device efficiencies.

  15. Trapping low-energy antiprotons in an ion trap

    SciTech Connect

    Fei, Xiang.

    1990-01-01

    A fraction of antiprotons from the Low Energy Antiproton Ring (LEAR) of CERN are slowed from 5.9 MeV to below 3 keV as they pass through thin foils. Transmitted particle energy distribution and low energy antiproton yield are measured by a time-of-flight technique. The difference in the range of protons and antiprotons (known as the Barkas effect) is observed. While still in flight, up to 1.3 {times} 10{sup 5} antiprotons with energies between 0 eV to 3 keV are stored in an ion trap from a single pulse of 5.9 MeV antiprotons leaving LEAR, thus a trapping efficiency exceeding of 4 {times} 10{sup {minus}4} is established. Trapped antiprotons maintain their initial energy distribution unless allowed to collide with a cloud of trapped electrons, whereupon they slow and cool below 1 meV in 10 s, and fall into a harmonic potential well suited for precision mass measurements. The slowing, trapping and cooling of antiprotons are the main focus of this thesis. The stored antiprotons are in thermal equilibrium at 4.2 K. In this ion trap, the antiproton cyclotron frequency is measured and compared with the proton (or electron) cyclotron frequency. The new measured ratio of the antiproton and proton inertial masses, with its 4 {times} 10{sup {minus}8} uncertainty, is more than three orders of magnitude more accurate than previous measurements using exotic atoms. This is a most precise test of CPT invariance with baryons. The antiproton lifetime in an ion trap was measured to be more than 103 days by trapping a cloud of antiprotons for 59 days. The indicates the number density of atoms is less than 100/cm{sup 3} which corresponds to the pressure in the vacuum chamber being less than 5 {times} 10{sup {minus}17} Torr at 4.2 K if we apply the ideal gas law.

  16. Managing resonant-trapped orbits in our Galaxy

    NASA Astrophysics Data System (ADS)

    Binney, James

    2016-11-01

    Galaxy modelling is greatly simplified by assuming the existence of a global system of angle-action coordinates. Unfortunately, global angle-action coordinates do not exist because some orbits become trapped by resonances, especially where the radial and vertical frequencies coincide. We show that in a realistic Galactic potential such trapping occurs only on thick-disc and halo orbits (speed relative to the guiding centre ≳ 80 km s- 1). We explain how the TORUS MAPPER code (TM) behaves in regions of phase space in which orbits are resonantly trapped, and we extend TM so that trapped orbits can be manipulated as easily as untrapped ones. The impact that the resonance has on the structure of velocity space depends on the weights assigned to trapped orbits. The impact is everywhere small if each trapped orbit is assigned the phase space density equal to the time average along the orbit of the DF for untrapped orbits. The impact could be significant with a different assignment of weights to trapped orbits.

  17. Weak Interaction Measurements with Optically Trapped Radioactive Atoms

    SciTech Connect

    Vieira, D.J.; Crane, S.G.; Guckert, R.; Zhao, X.; Brice, S.J.; Goldschmidt, A.; Hime, A.; Tupa, D.

    1999-07-16

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of this project is to apply the latest in magneto-optical and pure magnetic trapping technology to concentrate, cool, confine, and polarize radioactive atoms for precise electroweak interaction measurements. In particular, the authors have concentrated their efforts on the trapping of {sup 82}Rb for a parity-violating, beta-asymmetry measurement. Progress has been made in successfully trapping of up to 6 million {sup 82}Rb(t{sub 1/2}=75s) atoms in a magneto-optical trap coupled to a mass separator. This represents a two order of magnitude improvement in the number trapped radioactive atoms over all previous work. They have also measured the atomic hyperfine structure of {sup 82}Rb and demonstrated the MOT-to-MOT transfer and accumulation of atoms in a second trap. Finally, they have constructed and tested a time-orbiting-potential magnetic trap that will serve as a rotating beacon of spin-polarized nuclei and a beta-telescope detection system. Prototype experiments are now underway with the initial goal of making a 1% measurements of the beta-asymmetry parameter A which would match the world's best measurements.

  18. The Sheet Trapped in a Plumber's Nightmare

    NASA Astrophysics Data System (ADS)

    O'Bryan, Christopher; Bhattacharjee, Tapomoy; Sawyer, W. Gregory; Angelini, Thomas

    Block co-polymer systems offer exquisite control in the molecular-level design of self-assembled structures. The application of block copolymer phases has been generally limited to their use as bulk stabilizing agents in mass produced commodity chemicals and plastics. Recently, we have found the complex phase structures of self-assembled styrene ethylene/propylene diblock and styrene ethylene/butylene triblock co-polymers useful in 3D printing of other soft materials; the co-polymer structure yields around a writing nozzle as it moves through space while leaving material (polymers or colloids) trapped in the form of programmed structures. However, the relationship between the structural phase of the co-polymer self-assembly and its ability to support printed soft matter materials is not understood. In this study, we explore how different block co-polymer assemblies interact with and support soft matter materials once localized yielding has occurred.

  19. CO2 Capillary-Trapping Processes in Deep Saline Aquifers

    NASA Astrophysics Data System (ADS)

    Gershenzon, Naum I.; Soltanian, Mohamadreza; Ritzi, Robert W., Jr.; Dominic, David F.

    2014-05-01

    The idea of reducing the Earth's greenhouse effect by sequestration of CO2 into the Earth's crust has been discussed and evaluated for more than two decades. Deep saline aquifers are the primary candidate formations for realization of this idea. Evaluation of reservoir capacity and the risk of CO2 leakage require a detailed modeling of the migration and distribution of CO2 in the subsurface structure. There is a finite risk that structural (or hydrodynamic) trapping by caprock may be compromised (e.g. by improperly abandoned wells, stratigraphic discontinuities, faults, etc.). Therefore, other trapping mechanisms (capillary trapping, dissolution, and mineralization) must be considered. Capillary trapping may be very important in providing a "secondary-seal", and is the focus of our investigation. The physical mechanism of CO2 trapping in porous media by capillary trapping incorporates three related processes, i.e. residual trapping, trapping due to hysteresis of the relative permeability, and trapping due to hysteresis of the capillary pressure. Additionally CO2 may be trapped in heterogeneous media due to difference in capillary pressure entry points for different materials. The amount of CO2 trapped by these processes is a complicated nonlinear function of the spatial distribution of permeability, permeability anisotropy, capillary pressure, relative permeability of brine and CO2, permeability hysteresis and residual gas saturation (as well as the rate, total amount and placement of injected CO2). Geological heterogeneities essentially affect the dynamics of a CO2 plume in subsurface environments. Recent studies have led to new conceptual and quantitative models for sedimentary architecture in fluvial deposits over a range of scales that are relevant to the performance of some deep saline reservoirs [1, 2]. We investigated how the dynamics of a CO2 plume, during and after injection, is influenced by the hierarchical and multi-scale stratal architecture in such

  20. Hydrodynamic enhanced dielectrophoretic particle trapping

    DOEpatents

    Miles, Robin R.

    2003-12-09

    Hydrodynamic enhanced dielectrophoretic particle trapping carried out by introducing a side stream into the main stream to squeeze the fluid containing particles close to the electrodes producing the dielelectrophoretic forces. The region of most effective or the strongest forces in the manipulating fields of the electrodes producing the dielectrophoretic forces is close to the electrodes, within 100 .mu.m from the electrodes. The particle trapping arrangement uses a series of electrodes with an AC field placed between pairs of electrodes, which causes trapping of particles along the edges of the electrodes. By forcing an incoming flow stream containing cells and DNA, for example, close to the electrodes using another flow stream improves the efficiency of the DNA trapping.

  1. Vortex dynamics in anisotropic traps

    SciTech Connect

    McEndoo, S.; Busch, Th.

    2010-07-15

    We investigate the dynamics of linear vortex lattices in anisotropic traps in two dimensions and show that the interplay between the rotation and the anisotropy leads to a rich but highly regular dynamics.

  2. Experimental investigation of planar ion traps

    SciTech Connect

    Pearson, C. E.; Leibrandt, D. R.; Bakr, W. S.; Mallard, W. J.; Brown, K. R.; Chuang, I. L.

    2006-03-15

    Chiaverini et al. [Quantum Inf. Comput. 5, 419 (2005)] recently suggested a linear Paul trap geometry for ion-trap quantum computation that places all of the electrodes in a plane. Such planar ion traps are compatible with modern semiconductor fabrication techniques and can be scaled to make compact, many-zone traps. In this paper we present an experimental realization of planar ion traps using electrodes on a printed circuit board to trap linear chains of tens of charged particles of 0.44 {mu}m diameter in a vacuum of 15 Pa (10{sup -1} torr). With these traps we address concerns about the low trap depth of planar ion traps and develop control electrode layouts for moving ions between trap zones without facing some of the technical difficulties involved in an atomic ion-trap experiment. Specifically, we use a trap with 36 zones (77 electrodes) arranged in a cross to demonstrate loading from a traditional four-rod linear Paul trap, linear ion movement, splitting and joining of ion chains, and movement of ions through intersections. We further propose an additional dc-biased electrode above the trap which increases the trap depth dramatically, and a planar ion-trap geometry that generates a two-dimensional lattice of point Paul traps.

  3. Trapping and evolution dynamics of strongly magnetized cold gases

    NASA Astrophysics Data System (ADS)

    Choi, Jae-Hoon

    Cold Rydberg atoms and ultracold plasmas have been studied in the strong-magnetization regime. In this new territory, novel atomic and plasma states---such as guiding-center drift Rydberg attains and strongly magnetized, quasi-neutral, ultracold plasmas---have been created and investigated. The evolution dynamics studies of these exotic diamagnetic forms of matter, made possible by implementing a superconducting magnetic atom trap, revealed rich dynamical features in the systems: The Landau-quantized energy structure has led to entirely different evolutions of the highly excited atoms in laser-excited or drift Rydberg states than in magnetic-field-free cases; and the presence of the strong magnetic field has drastically altered the collisional behavior and expansion dynamics of the plasmas. Furthermore, atom cooling and trapping methodology has been extended in multiple directions. Firstly, laser cooling and magnetic trapping of ground-state atoms has been demonstrated in magnetic; fields exceeding 3 Tesla, representing a 20-fold increase in the field-strength of cold-atom traps. Secondly, the trapping of Rydberg atoms with a lifetime of 80 ms has been achieved. This trapping technique exploits the quasi-free nature of Rydberg electrons, which can be adopted in other forms of Rydberg-atom trapping. Lastly; the trapping of two-component, ultracold plasmas has been demonstrated in a nested Penning-trap configuration. The confinement of quasi-neutral ultracold plasmas allowed us to observe novel effects such as the correlation between the ionic oscillation and the electron energy distribution.

  4. Science, conservation, and camera traps

    USGS Publications Warehouse

    Nichols, James D.; Karanth, K. Ullas; O'Connel, Allan F.; O'Connell, Allan F.; Nichols, James D.; Karanth, K. Ullas

    2011-01-01

    Biologists commonly perceive camera traps as a new tool that enables them to enter the hitherto secret world of wild animals. Camera traps are being used in a wide range of studies dealing with animal ecology, behavior, and conservation. Our intention in this volume is not to simply present the various uses of camera traps, but to focus on their use in the conduct of science and conservation. In this chapter, we provide an overview of these two broad classes of endeavor and sketch the manner in which camera traps are likely to be able to contribute to them. Our main point here is that neither photographs of individual animals, nor detection history data, nor parameter estimates generated from detection histories are the ultimate objective of a camera trap study directed at either science or management. Instead, the ultimate objectives are best viewed as either gaining an understanding of how ecological systems work (science) or trying to make wise decisions that move systems from less desirable to more desirable states (conservation, management). Therefore, we briefly describe here basic approaches to science and management, emphasizing the role of field data and associated analyses in these processes. We provide examples of ways in which camera trap data can inform science and management.

  5. Collisionless microtearing modes in hot tokamaks: Effect of trapped electrons

    SciTech Connect

    Swamy, Aditya K.; Ganesh, R.; Brunner, S.; Vaclavik, J.; Villard, L.

    2015-07-15

    Collisionless microtearing modes have recently been found linearly unstable in sharp temperature gradient regions of large aspect ratio tokamaks. The magnetic drift resonance of passing electrons has been found to be sufficient to destabilise these modes above a threshold plasma β. A global gyrokinetic study, including both passing electrons as well as trapped electrons, shows that the non-adiabatic contribution of the trapped electrons provides a resonant destabilization, especially at large toroidal mode numbers, for a given aspect ratio. The global 2D mode structures show important changes to the destabilising electrostatic potential. The β threshold for the onset of the instability is found to be generally downshifted by the inclusion of trapped electrons. A scan in the aspect ratio of the tokamak configuration, from medium to large but finite values, clearly indicates a significant destabilizing contribution from trapped electrons at small aspect ratio, with a diminishing role at larger aspect ratios.

  6. Entropic cages for trapping DNA near a nanopore.

    PubMed

    Liu, Xu; Mihovilovic Skanata, Mirna; Stein, Derek

    2015-01-01

    Nanopores can probe the structure of biopolymers in solution; however, diffusion makes it difficult to study the same molecule for extended periods. Here we report devices that entropically trap single DNA molecules in a 6.2-femtolitre cage near a solid-state nanopore. We electrophoretically inject DNA molecules into the cage through the nanopore, pause for preset times and then drive the DNA back out through the nanopore. The saturating recapture time and high recapture probability after long pauses, their agreement with a convection-diffusion model and the observation of trapped DNA under fluorescence microscopy all confirm that the cage stably traps DNA. Meanwhile, the cages have 200 nm openings that make them permeable to small molecules, like the restriction endonuclease we use to sequence-specifically cut trapped DNA into fragments whose number and sizes are analysed upon exiting through the nanopore. Entropic cages thus serve as reactors for chemically modifying single DNA molecules. PMID:25648853

  7. Towards Non-Equilibrium Dynamics with Trapped Ions

    NASA Astrophysics Data System (ADS)

    Silbert, Ariel; Jubin, Sierra; Doret, Charlie

    2016-05-01

    Atomic systems are superbly suited to the study of non-equilibrium dynamics. These systems' exquisite isolation from environmental perturbations leads to long relaxation times that enable exploration of far-from-equilibrium phenomena. One example of particular relevance to experiments in trapped ion quantum information processing, metrology, and precision spectroscopy is the approach to thermal equilibrium of sympathetically cooled linear ion chains. Suitable manipulation of experimental parameters permits exploration of the quantum-to-classical crossover between ballistic transport and diffusive, Fourier's Law conduction, a topic of interest not only to the trapped ion community but also for the development of microelectronic devices and other nanoscale structures. We present progress towards trapping chains of multiple co-trapped calcium isotopes geared towards measuring thermal equilibration and discuss plans for future experiments in non-equilibrium statistical mechanics. This work is supported by Cottrell College Science Award from the Research Corporation for Science Advancement and by Williams College.

  8. Electron source for a mini ion trap mass spectrometer

    DOEpatents

    Dietrich, D.D.; Keville, R.F.

    1995-12-19

    An ion trap is described which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10{sup 9} and commercial mass spectrometers requiring 10{sup 4} ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products. 10 figs.

  9. Electron source for a mini ion trap mass spectrometer

    DOEpatents

    Dietrich, Daniel D.; Keville, Robert F.

    1995-01-01

    An ion trap which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10.sup.9 and commercial mass spectrometers requiring 10.sup.4 ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products.

  10. Entropic cages for trapping DNA near a nanopore

    NASA Astrophysics Data System (ADS)

    Liu, Xu; Skanata, Mirna Mihovilovic; Stein, Derek

    2015-02-01

    Nanopores can probe the structure of biopolymers in solution; however, diffusion makes it difficult to study the same molecule for extended periods. Here we report devices that entropically trap single DNA molecules in a 6.2-femtolitre cage near a solid-state nanopore. We electrophoretically inject DNA molecules into the cage through the nanopore, pause for preset times and then drive the DNA back out through the nanopore. The saturating recapture time and high recapture probability after long pauses, their agreement with a convection-diffusion model and the observation of trapped DNA under fluorescence microscopy all confirm that the cage stably traps DNA. Meanwhile, the cages have 200 nm openings that make them permeable to small molecules, like the restriction endonuclease we use to sequence-specifically cut trapped DNA into fragments whose number and sizes are analysed upon exiting through the nanopore. Entropic cages thus serve as reactors for chemically modifying single DNA molecules.

  11. Ion beam analysis of defect trapping

    NASA Astrophysics Data System (ADS)

    Swanson, M. L.; Howe, L. M.

    1983-12-01

    Channeling measurements using medium energy ions (e.g. 1 MeV He +) have been used to determine the positions of solute atoms which are displaced from lattice sites by the trapping of vacancies and self-interstitial atoms. In this way, some simple defect trapping configurations have been identified in fcc metals. One of these is the mixed dumbbell (created when a self-interstitial is trapped by a small solute atom), consisting of a host atom and solute atom stradding a normal lattice site. Another is the tetravacancy-solute atom complex, consisting of four nearest neighbour vacancies surrounding a solute atom displaced into the tetrahedral interstitial site. In addition, from detailed analyses of displacements into different crystallographic channels as a function of irradiation fluence and annealing temperature, the evolution of a variety of defect complexes containing self-interstitials or vacancies has been studied in Al, Cu, Ni, Fe, and Mg crystals. Information from channeling analyses will be compared with data obtained from measurements of electrical resistivity, Mössbauer effect, perturbed angular correlation, extended X-ray absorption fine structure, muon precession, positron annihilation and internal friction. The advantages of the different methods will be discussed.

  12. Ion Trap Array-Based Systems And Methods For Chemical Analysis

    DOEpatents

    Whitten, William B [Oak Ridge, TN; Ramsey, J Michael [Knoxville, TN

    2005-08-23

    An ion trap-based system for chemical analysis includes an ion trap array. The ion trap array includes a plurality of ion traps arranged in a 2-dimensional array for initially confining ions. Each of the ion traps comprise a central electrode having an aperture, a first and second insulator each having an aperture sandwiching the central electrode, and first and second end cap electrodes each having an aperture sandwiching the first and second insulator. A structure for simultaneously directing a plurality of different species of ions out from the ion traps is provided. A spectrometer including a detector receives and identifies the ions. The trap array can be used with spectrometers including time-of-flight mass spectrometers and ion mobility spectrometers.

  13. Imaging electronic trap states in perovskite thin films with combined fluorescence and femtosecond transient absorption microscopy

    DOE PAGES

    Xiao, Kai; Ma, Ying -Zhong; Simpson, Mary Jane; Doughty, Benjamin; Yang, Bin

    2016-04-22

    Charge carrier trapping degrades the performance of organometallic halide perovskite solar cells. To characterize the locations of electronic trap states in a heterogeneous photoactive layer, a spatially resolved approach is essential. Here, we report a comparative study on methylammonium lead tri-iodide perovskite thin films subject to different thermal annealing times using a combined photoluminescence (PL) and femtosecond transient absorption microscopy (TAM) approach to spatially map trap states. This approach coregisters the initially populated electronic excited states with the regions that recombine radiatively. Although the TAM images are relatively homogeneous for both samples, the corresponding PL images are highly structured. Themore » remarkable variation in the PL intensities as compared to transient absorption signal amplitude suggests spatially dependent PL quantum efficiency, indicative of trapping events. Furthermore, detailed analysis enables identification of two trapping regimes: a densely packed trapping region and a sparse trapping area that appear as unique spatial features in scaled PL maps.« less

  14. Progress at the Penning Trap Mass Spectrometer ``THe-Trap''

    NASA Astrophysics Data System (ADS)

    Hoecker, Martin; Eronen, Tommi; Ketter, Jochen; Streubel, Sebastian; Blaum, Klaus; van Dyck, Robert S.

    2012-03-01

    In 2008, the ``University of Washington Penning-Trap Mass Spectrometer'' (UW-PTMS), originally designed and built by the Van Dyck group, was moved to the Max-Planck-Insitute for Nuclear Physics in Heidelberg, Germany. It was set up in a dedicated laboratory that meets both the radiation-safety requirements, and the environment-stabilization demands for a high-precision measurement of the tritium/helium-3 mass ratio. Our goal is to measure this mass ratio with a relative uncertainty of 10-11, which would be more than an order of magnitude better than the previous best measurement. It would decrease the uncertainty in the tritium beta decay Q-value (an important parameter in the ongoing search for the neutrino mass by experiments such as KATRIN) by the same factor. In order to emphasize the specialization of our experiment with regard to Tritium and ^3Helium, it was renamed to ``THe-Trap''. THe-Trap features a double Penning-trap for rapid ion exchange, an external ion source to minimize trap contamination, a novel Zener-based voltage source, and active as well as passive stabilization of temperature, pressure and the magnetic field of the superconducting magnet. An overview of the project and a report on the recent progress will be given.

  15. Universal collisional activation ion trap mass spectrometry

    DOEpatents

    McLuckey, S.A.; Goeringer, D.E.; Glish, G.L.

    1993-04-27

    A universal collisional activation ion trap comprises an ion trapping means containing a bath gas and having connected thereto a noise signal generator. A method of operating a universal collisional activation ion trap comprises the steps of: providing an ion trapping means; introducing into the ion trapping means a bath gas; and, generating a noise signal within the ion trapping means; introducing into the ion trapping means a substance that, when acted upon by the noise signal, undergoes collisional activation to form product ions.

  16. Universal collisional activation ion trap mass spectrometry

    DOEpatents

    McLuckey, Scott A.; Goeringer, Douglas E.; Glish, Gary L.

    1993-01-01

    A universal collisional activation ion trap comprises an ion trapping means containing a bath gas and having connected thereto a noise signal generator. A method of operating a universal collisional activation ion trap comprises the steps of: providing an ion trapping means; introducing into the ion trapping means a bath gas; and, generating a noise signal within the ion trapping means; introducing into the ion trapping means a substance that, when acted upon by the noise signal, undergoes collisional activation to form product ions.

  17. Experimental observation of light trapping in hydrogenated amorphous silicon solar cells

    NASA Astrophysics Data System (ADS)

    Faughnan, B. W.

    1985-10-01

    Experimental evidence for light trapping in glass/conductive transparent oxide/p-i-n/ metal hydrogenated amorphous silicon solar cell structures is presented. A short-circuit current of 17.8 mA/sq cm has previously been reported for a cell made with this structure. The light trapping is treated by a modification of the Yablonovitch-Cody (YC) statistical theory of light trapping in textured layers (Yablonovitch and Cody, 1982). Reflection measurements show that 80 percent of the incident light is trapped. Quantum efficiency measurements made on cells with back electrode metals of different reflectivity are shown to be in agreement with the predictions of the YC theory.

  18. Live trapping of hawks and owls

    USGS Publications Warehouse

    Stewart, R.E.; Cope, J.B.; Robbins, C.S.

    1945-01-01

    1. Hawks of six species (80 individuals) and owls of five species (37 individuals) were trapped for banding from November 1, 1943, to. May 26,1944. 2. In general, pole traps proved better than hand-operated traps or automatic traps using live bait. 3. Verbail pole traps proved very efficient, and were much more humane than padded steel traps because they rarely injured a captured bird. 4: Unbaited Verbail traps took a variety of raptors, in rough proportion to their local abundance, although slightly more of beneficial species were caught than of harmful types. 5. Hawks and owls were retrapped more readily in Verbail traps than in other types tried. 6. The number of song birds caught in Verbail traps was negligible. 7. Crows and vultures were not taken in Verbail traps, but possibly could be caught with bait.

  19. Effect of bait in live trapping Peromyscus

    USGS Publications Warehouse

    Stickel, L.F.

    1948-01-01

    SUMMARY: Evidence from live trapping tests indicated that Peromyscus leucopus did not leave their home ranges because of the attraction of trap bait in nearby areas. A trap line down the center of a heavily live-trapped area caught as many mice before the area trapping as afterward. Thus, there was reason to believe that the area trapping did not serve to pre-bait the mice. Two unbaited lines of live traps caught an equal number of Peromyscus. When one line was baited with rolled oats and peanut butter the efficiency of the traps was improved to the extent that the baited line captured more than twice as many mice as the unbaited line. It is concluded that for the species and habitat tested it is safe to make population calculations based on the assumption that the animals remain within their home ranges and do not tend to move into the trapped area because of the attraction of the trap bait.

  20. Comparison of emergence traps of different shape and translucency in the trapping of Culicoides (Diptera: Ceratopogonidae).

    PubMed

    Steinke, S; Lühken, R; Kroischke, F; Timmermann, E; Kiel, E

    2016-06-15

    Various types of emergence traps are available for investigations of the breeding habitats of Culicoides (Diptera: Ceratopogonidae). In order to assess the potential impact of the trap design on the trapping success, we compared the efficiency of opaque and white (more translucent) emergence traps and two trap shapes (cone-shaped and quadratic), to sample Culicoides emerging from cowpats. Significantly higher numbers of Culicoides chiopterus and Culicoides dewulfi were trapped with opaque traps, while there was no obvious effect of the trap shape. There were no distinct differences in the microclimate among different trap types. PMID:27198792

  1. Efficient sampling of ground-dwelling arthropods using pitfall traps in arid steppes.

    PubMed

    Cheli, Germán H; Corley, Juan C

    2010-01-01

    Pitfall trapping is probably the most frequently used method for sampling ground-dwelling arthropods. While the capture of specimens in pitfall traps largely depends on the number of individuals in the sampled area, trap design and trapping effort for a given environment, can also affect sampling success. The aim of this study was to determine the best pitfall trapping design for collecting ground-dwelling arthropods in the wind-blown and cold arid steppe areas of Patagonia. We tested four designs of traps, six types of preservative and different times of activation as well as the quantity of traps. Both preservation attributes and sampling efficiency differed between different trap designs and fluids compared. We conclude that in order to obtain reliable data on the structure of a community of ground-dwelling arthropods in Patagonia, at least three pitfall traps per experimental unit are required. In addition, traps should be opened for a minimum of 10 days filled with 300 ml of 30% ethylene glycol. We also suggested the use of a simple trap design (i. e. without funnel or roof). We believe these findings will contribute to more appropriate sampling of the ground dwelling fauna of Patagonia as well as other arid areas, leading to more reliable diversity studies. PMID:21271057

  2. Neutron Trapping using a Magneto-Gravitational Trap

    NASA Astrophysics Data System (ADS)

    Liu, Chen-Yu

    2014-03-01

    Eighty years after Chadwick discovered the neutron, physicists today still cannot agree on how long the neutron lives. Measurements of the neutron lifetime have achieved the 0.1% level of precision (~ 1 s). However, results from several recent experiments are up to 7 s lower than the (pre-2010) particle data group (PDG) value. Experiments using the trap technique yield lifetime results lower than those using the beam technique. The PDG urges the community to resolve this discrepancy, now 6.5 sigma. Measuring the absolute neutron lifetime is difficult because of several limitations: the low energy of the neutron decay products, the inability to track slow neutrons, and the fact that the neutron lifetime is long (880.1 +/- 1.1 s). Slow neutrons are susceptible to many loss mechanisms other than beta-decay, such as upscattering and absorption on material surfaces. Often, these interactions act on time scales comparable to the neutron beta-decay, making the extraction of the beta-decay lifetime particularly challenging. We will revisit this measurement by trapping ultracold neutrons (UCN) in a hybrid magnetic-gravitational trap. The trap consists of a Halbach array of permanent magnets, which can levitate UCN up to 50 neV. These neutrons are also confined vertically up to 0.5 m by gravity. Such a trap minimizes the chance of neutron interactions with material walls. In addition, the open-top geometry allows room to implement novel schemes to detect neutrons and decay particles in-situ. The UCN τ experiment aims to reduce the uncertainty of the neutron lifetime measurement to below 1 second. In this talk, I will report results of our first attempt to trap UCN in 2013 and discuss plans to quantify systematic effects. The work is supported by NSF grant PHY-1306942.

  3. Design of a mosquito trap support pole for use with CDC miniature light traps.

    PubMed

    Evans, Christopher L; Wozniak, Arthur; McKenna, Bruce; Vaughan, David R; Dowda, Michael C

    2005-03-01

    A mosquito trap support pole constructed from polyvinyl chloride and aluminum pipes was designed to hang a Centers for Disease Control and Prevention miniature light trap and dry ice container. Miniature light traps normally hang from tree branches. The trap support pole is designed to hang traps and dry ice bait in areas where no suitable trees exist. PMID:15825774

  4. Multiphoton polymerization using optical trap assisted nanopatterning

    NASA Astrophysics Data System (ADS)

    Leitz, Karl-Heinz; Tsai, Yu-Cheng; Flad, Florian; Schäffer, Eike; Quentin, Ulf; Alexeev, Ilya; Fardel, Romain; Arnold, Craig B.; Schmidt, Michael

    2013-06-01

    In this letter, we show the combination of multiphoton polymerization and optical trap assisted nanopatterning (OTAN) for the additive manufacturing of structures with nanometer resolution. User-defined patterns of polymer nanostructures are deposited on a glass substrate by a 3.5 μm polystyrene sphere focusing IR femtosecond laser pulses, showing minimum feature sizes of λ/10. Feature size depends on the applied laser fluence and the bead surface spacing. A finite element model describes the intensity enhancement in the microbead focus. The results presented suggest that OTAN in combination with multiphoton processing is a viable technique for additive nanomanufacturing with sub-diffraction-limited resolution.

  5. Determining average path length and average trapping time on generalized dual dendrimer

    NASA Astrophysics Data System (ADS)

    Li, Ling; Guan, Jihong

    2015-03-01

    Dendrimer has wide number of important applications in various fields. In some cases during transport or diffusion process, it transforms into its dual structure named Husimi cactus. In this paper, we study the structure properties and trapping problem on a family of generalized dual dendrimer with arbitrary coordination numbers. We first calculate exactly the average path length (APL) of the networks. The APL increases logarithmically with the network size, indicating that the networks exhibit a small-world effect. Then we determine the average trapping time (ATT) of the trapping process in two cases, i.e., the trap placed on a central node and the trap is uniformly distributed in all the nodes of the network. In both case, we obtain explicit solutions of ATT and show how they vary with the networks size. Besides, we also discuss the influence of the coordination number on trapping efficiency.

  6. Experiments with trapped radioactive ^210Fr

    NASA Astrophysics Data System (ADS)

    Simsarian, J. E.; Orozco, L. A.; Shi, W.; Sprouse, G. D.; Zhao, W. Z.

    1996-05-01

    Francium, the heaviest of alkali atoms, is an excellent system for studing parity non-conservation (PNC) in atoms because of its large atomic number. The lack of stable isotopes has made the study its atomic structure difficult. Some of the relevant energy levels necesary for a PNC measurement have not been observed. At the Stony Brook Superconducting LINAC we produce 1 × 10^6 ^210Fr/s in the reaction ^197Au(^18O,5n)^210Fr. The atoms are transported as ions to the vicinity of the trap where they are neutralized and enter a Magneto Optical Trap (MOT) in a glass cell. From the initial capture of about one thousand ^210Fr into a MOT (J. E. Simsarian, A. Ghosh, G. Gwinner, L. A. Orozco, G. D. Sprouse and P. A. Voytas (Preprint Dec. 12, 1995)) we have increased the number of atoms to the point where their fluorescence is visible in a CCD camera. The larger number of atoms permits experiments to study the atomic structure of francium, in particular the location of the 8S and 9S energy levels. The lifetime measurement of the 7P_3/2 will help test the theoretical understanding of its atomic structure. Work supported by a Precision Measurement Grant from NIST and by NSF.

  7. Trapping biases of Culex torrentium and Culex pipiens revealed by comparison of captures in CDC traps, ovitraps, and gravid traps.

    PubMed

    Hesson, Jenny C; Ignell, Rickard; Hill, Sharon R; Östman, Örjan; Lundström, Jan O

    2015-06-01

    We evaluate three trapping methods for their effectiveness at capturing Culex pipiens and Culex torrentium, both enzootic vectors of bird-associated viruses in Europe. The comparisons, performed in two regions in Sweden, were among CDC traps baited with carbon dioxide, gravid traps, and ovitraps baited with hay infusion. The proportions of the two Culex species in a catch differed between trap types, with CDC traps catching a lower proportion of Cx. torrentium than both gravid traps and ovitraps. Between gravid traps and ovitraps, there was no difference in the proportions of the two species. The results indicate that Cx. torrentium may go undetected or underestimated compared to Cx. pipiens when using carbon dioxide baited CDC traps. The new insight of trap bias presented here adds an important dimension to consider when investigating these vectors of bird-associated viruses in the field.

  8. Positron trapping at grain boundaries

    SciTech Connect

    Dupasquier, A. ); Romero, R.; Somoza, A. )

    1993-10-01

    The standard positron trapping model has often been applied, as a simple approximation, to the interpretation of positron lifetime spectra in situations of diffusion-controlled trapping. This paper shows that this approximation is not sufficiently accurate, and presents a model based on the correct solution of the diffusion equation, in the version appropriate for studying positron trapping at grain boundaries. The model is used for the analysis of new experimental data on positron lifetime spectra in a fine-grained Al-Ca-Zn alloy. Previous results on similar systems are also discussed and reinterpreted. The analysis yields effective diffusion coefficients not far from the values known for the base metals of the alloys.

  9. Thermal detection of trapped charge carriers in organic transport materials

    NASA Astrophysics Data System (ADS)

    von Malm, Norwin; Steiger, Juergen; Finnberg, Torsten; Schmechel, Roland; von Seggern, Heinz

    2003-03-01

    The effect of trap states on the transport and luminescence properties of organic light emitting diodes (OLEDs) is studied. For trap level detection energy resolved thermally stimulated current (TSC) measurements known as fractional glow are utilized to determine the density of occupied states (DOOS) in various organic semiconductors such as the small molecule systems Alq3 [aluminum tris(8-hydroxyquinoline)], 1-NaphDATA {4,4',4"-tris-[N-(1-naphtyl)-N-phenylamino]-triphenylamine} and α-NPD [N,N'-di-(1-naphthyl)-N,N'-diphenylbenzidine] and the polymeric semiconductor MDMO-PPV {poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene]}. Characteristic differences in the trap spectra are obtained and interpreted in terms of possible structural and compositional origins of the investigated materials. In order to judge the formation process of traps and their practical consequences on the charge carrier transport I-V and L-V characteristics of 1-NaphDATA doped α-NPD devices and α-NPD doped 1-NaphDATA devices were compared to respective non-doped samples. A clearly reduced current and luminescence was found only in the former case. It was possible to conclude that the detected electronic trap states either act as hole traps or as scattering centers. Furthermore, pulsed transport studies on ITO/α-NPD/Alq3/Al devices show thte critical influence of traps on the dynamical performance of the charge transport. In a two-pulse experiment the carrier injection and trap depletion can be separated.

  10. Salisbury hospital's steam trap success.

    PubMed

    Baillie, Jonathan

    2011-03-01

    With the Carbon Reduction Commitment now fully in force, and the NHS tasked with achieving tough carbon emission reduction targets in line with both UK and EU mandates, healthcare estates teams across the country are seeking cost-effective ways to reduce energy consumption. Against this backdrop, Salisbury District Hospital has implemented a concerted energy-saving programme, key elements of which include replacing existing bucket steam traps with higher performing, lower maintenance, and more effective GEM venturi steam traps from Thermal Energy International (TEI), installing a new gas CHP engine, and looking into fitting a TEI condensate economiser system. PMID:21485315

  11. Salisbury hospital's steam trap success.

    PubMed

    Baillie, Jonathan

    2011-03-01

    With the Carbon Reduction Commitment now fully in force, and the NHS tasked with achieving tough carbon emission reduction targets in line with both UK and EU mandates, healthcare estates teams across the country are seeking cost-effective ways to reduce energy consumption. Against this backdrop, Salisbury District Hospital has implemented a concerted energy-saving programme, key elements of which include replacing existing bucket steam traps with higher performing, lower maintenance, and more effective GEM venturi steam traps from Thermal Energy International (TEI), installing a new gas CHP engine, and looking into fitting a TEI condensate economiser system.

  12. Ion trapping in Recycler Ring

    SciTech Connect

    K.Y. Ng

    2004-06-28

    Transverse instabilities have been observed in the antiproton beam stored in the Fermilab Recycler Ring, resulting in a sudden increase in the transverse emittances and a small beam loss. The instabilities appear to occur a few hours after a change in the ramping pattern of the Main Injector which shares the same tunnel. The phenomena have been studied by inducing similar instabilities. However, the mechanism is still unknown. A possible explanation is that the ions trapped in the beam reach such an intensity that collective coupled transverse oscillation occurs. However, there is no direct evidence of the trapped ions at this moment.

  13. Dysprosium magneto-optical traps

    SciTech Connect

    Youn, Seo Ho; Lu Mingwu; Ray, Ushnish; Lev, Benjamin L.

    2010-10-15

    Magneto-optical traps (MOTs) of highly magnetic lanthanides open the door to explorations of novel phases of strongly correlated matter such as lattice supersolids and quantum liquid crystals. We recently reported the first MOTs of the five high-abundance isotopes of the most magnetic atom, dysprosium. Described here are details of the experimental technique employed for repumper-free Dy MOTs containing up to half a billion atoms. Extensive characterization of the MOTs' properties--population, temperature, loading, metastable decay dynamics, and trap dynamics--is provided.

  14. Microwave regenerated particulate trap

    SciTech Connect

    McDonald, A.C. Jr.; Yonushonis, T.M.; Haberkamp, W.C.; Mako, F.; Len, L.K,; Silberglitt, R.; Ahmed, I.

    1997-12-31

    It has been demonstrated that a fibrous particulate filter can extract particulate matter from the diesel exhaust. However, additional engineering efforts remains to achieve the design target of 90%. It has also be shown that with minor modifications magnetrons produced for home ovens can endure a simulated diesel operating environment. Much work remains to develop a robust product ready to complete extensive engine testing and evaluation. These efforts include: (1) additional environmental testing of magnetrons; (2) vibration testing of the filter in the housing; (3) evaluating alternative methods/designs to seal the center bore; and (4) determining the optimum coating thickness that provides sufficient structural integrity while maintaining rapid heating rates.

  15. Bacteria can mobilize nematode-trapping fungi to kill nematodes

    PubMed Central

    Wang, Xin; Li, Guo-Hong; Zou, Cheng-Gang; Ji, Xing-Lai; Liu, Tong; Zhao, Pei-Ji; Liang, Lian-Ming; Xu, Jian-Ping; An, Zhi-Qiang; Zheng, Xi; Qin, Yue-Ke; Tian, Meng-Qing; Xu, You-Yao; Ma, Yi-Cheng; Yu, Ze-Fen; Huang, Xiao-Wei; Liu, Shu-Qun; Niu, Xue-Mei; Yang, Jin-Kui; Huang, Ying; Zhang, Ke-Qin

    2014-01-01

    In their natural habitat, bacteria are consumed by bacterivorous nematodes; however, they are not simply passive preys. Here we report a defensive mechanism used by certain bacteria to mobilize nematode-trapping fungi to kill nematodes. These bacteria release urea, which triggers a lifestyle switch in the fungus Arthrobotrys oligospora from saprophytic to nematode–predatory form; this predacious form is characterized by formation of specialized cellular structures or ‘traps’. The bacteria significantly promote the elimination of nematodes by A. oligospora. Disruption of genes involved in urea transport and metabolism in A. oligospora abolishes the urea-induced trap formation. Furthermore, the urea metabolite ammonia functions as a signal molecule in the fungus to initiate the lifestyle switch to form trap structures. Our findings highlight the importance of multiple predator–prey interactions in prey defense mechanisms. PMID:25514608

  16. Track and trap in 3D

    NASA Astrophysics Data System (ADS)

    Glückstad, Jesper; Rodrigo, Peter J.; Nielsen, Ivan P.; Alonzo, Carlo A.

    2007-04-01

    Three-dimensional light structures can be created by modulating the spatial phase and polarization properties of an an expanded laser beam. A particularly promising technique is the Generalized Phase Contrast (GPC) method invented and patented at Risø National Laboratory. Based on the combination of programmable spatial light modulator devices and an advanced graphical user-interface the GPC method enables real-time, interactive and arbitrary control over the dynamics and geometry of synthesized light patterns. Recent experiments have shown that GPC-driven micro-manipulation provides a unique technology platform for fully user-guided assembly of a plurality of particles in a plane, control of particle stacking along the beam axis, manipulation of multiple hollow beads, and the organization of living cells into three-dimensional colloidal structures. Here we present GPC-based optical micromanipulation in a microfluidic system where trapping experiments are computer-automated and thereby capable of running with only limited supervision. The system is able to dynamically detect living yeast cells using a computer-interfaced CCD camera, and respond to this by instantly creating traps at positions of the spotted cells streaming at flow velocities that would be difficult for a human operator to handle.

  17. Assessment of vector/host contact: comparison of animal-baited traps and UV-light/suction trap for collecting Culicoides biting midges (Diptera: Ceratopogonidae), vectors of Orbiviruses

    PubMed Central

    2011-01-01

    Background The emergence and massive spread of bluetongue in Western Europe during 2006-2008 had disastrous consequences for sheep and cattle production and confirmed the ability of Palaearctic Culicoides (Diptera: Ceratopogonidae) to transmit the virus. Some aspects of Culicoides ecology, especially host-seeking and feeding behaviors, remain insufficiently described due to the difficulty of collecting them directly on a bait animal, the most reliable method to evaluate biting rates. Our aim was to compare typical animal-baited traps (drop trap and direct aspiration) to both a new sticky cover trap and a UV-light/suction trap (the most commonly used method to collect Culicoides). Methods/results Collections were made from 1.45 hours before sunset to 1.45 hours after sunset in June/July 2009 at an experimental sheep farm (INRA, Nouzilly, Western France), with 3 replicates of a 4 sites × 4 traps randomized Latin square using one sheep per site. Collected Culicoides individuals were sorted morphologically to species, sex and physiological stages for females. Sibling species were identified using a molecular assay. A total of 534 Culicoides belonging to 17 species was collected. Abundance was maximal in the drop trap (232 females and 4 males from 10 species) whereas the diversity was the highest in the UV-light/suction trap (136 females and 5 males from 15 species). Significant between-trap differences abundance and parity rates were observed. Conclusions Only the direct aspiration collected exclusively host-seeking females, despite a concern that human manipulation may influence estimation of the biting rate. The sticky cover trap assessed accurately the biting rate of abundant species even if it might act as an interception trap. The drop trap collected the highest abundance of Culicoides and may have caught individuals not attracted by sheep but by its structure. Finally, abundances obtained using the UV-light/suction trap did not estimate accurately Culicoides

  18. Microfabricated linear Paul-Straubel ion trap

    DOEpatents

    Mangan, Michael A.; Blain, Matthew G.; Tigges, Chris P.; Linker, Kevin L.

    2011-04-19

    An array of microfabricated linear Paul-Straubel ion traps can be used for mass spectrometric applications. Each ion trap comprises two parallel inner RF electrodes and two parallel outer DC control electrodes symmetric about a central trap axis and suspended over an opening in a substrate. Neighboring ion traps in the array can share a common outer DC control electrode. The ions confined transversely by an RF quadrupole electric field potential well on the ion trap axis. The array can trap a wide array of ions.

  19. Microtrap electrode devices for single cell trapping and impedance measurement.

    PubMed

    Mondal, D; Roychaudhuri, C; Das, L; Chatterjee, J

    2012-10-01

    This paper reports the design and fabrication of electrode microtraps for single cell trapping and impedance measurement. In this work, the microtrap electrodes of parallel and elliptical geometry have been fabricated by electroplating of gold electrodes of optimum thickness. This has enabled the formation of electrode traps without requiring any precision alignment between separate insulating traps like PDMS and the bottom gold electrodes. Further the improved uniformity of the electric field between the trapping electrodes as observed from COVENTORWARE simulation significantly reduces the effect of cell position inside the microwell on the electrical measurement unlike previous reports. This makes it possible to directly extract the equivalent cell parameters from the electrical measurement without introducing any correction factor corresponding to cell position. We have performed impedance spectroscopy with both the microwell electrode structures with single HeLa cell at two different positions of trapping. It has been observed that there is almost no change in the extracted values of cell resistance and capacitance for different positions within parallel electrodes and there is only 0.7 % and 0.85 % change in cell resistance and capacitance for the two positions within elliptical electrodes. Thus these microwell electrode structures can be used as an improved and a more convenient platform for single cell electrical characterization. PMID:22767244

  20. Some Examples of Trapped Surfaces

    NASA Astrophysics Data System (ADS)

    Bengtsson, Ingemar

    2013-03-01

    We present some simple pen and paper examples of trapped surfaces in order to help in visualising this key concept of the theory of gravitational collapse. We collect these examples from time-symmetric initial data, 2+1 dimensions, collapsing null shells, and the Vaidya solution.

  1. Optical trapping of coated microspheres.

    PubMed

    Bormuth, Volker; Jannasch, Anita; Ander, Marcel; van Kats, Carlos M; van Blaaderen, Alfons; Howard, Jonathon; Schäffer, Erik

    2008-09-01

    In an optical trap, micron-sized dielectric particles are held by a tightly focused laser beam. The optical force on the particle is composed of an attractive gradient force and a destabilizing scattering force. We hypothesized that using anti-reflection-coated microspheres would reduce scattering and lead to stronger trapping. We found that homogeneous silica and polystyrene microspheres had a sharp maximum trap stiffness at a diameter of around 800 nm--the trapping laser wavelength in water--and that a silica coating on a polystyrene microsphere was a substantial improvement for larger diameters. In addition, we noticed that homogeneous spheres of a correct size demonstrated anti-reflective properties. Our results quantitatively agreed with Mie scattering calculations and serve as a proof of principle. We used a DNA stretching experiment to confirm the large linear range in detection and force of the coated microspheres and performed a high-force motor protein assay. These measurements show that the surfaces of the coated microspheres are compatible with biophysical assays.

  2. VACUUM TRAP AND VALVE COMBINATION

    DOEpatents

    Milleron, N.; Levenson, L.

    1963-02-19

    This patent relates to a vacuum trap and valve combination suitable for use in large ultra-high vacuum systems. The vacuum trap is a chamber having an inlet and outlet opening which may be made to communicate with a chamber to be evacuated and a diffusion pump, respectively. A valve is designed to hermeticaliy seal with inlet opening and, when opened, block the line-of- sight'' between the inlet and outlet openings, while allowing a large flow path between the opened vaive and the side walls of the trap. The interior of the trap and the side of the valve facing the inlet opening are covered with an impurity absorbent, such as Zeolite or activated aluminum. Besides the advantage of combining two components of a vacuum system into one, the present invention removes the need for a baffle between the pump and the chamber to be evacuated. In one use of a specific embodiment of this invention, the transmission probability was 45 and the partial pressure of the pump fluid vapor in the vacuum chamber was at least 100 times lower than its vapor pressure. (AEC)

  3. Mass Trapping for Anastrepha suspensa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ABSTRACT In field tests conducted in south Florida to test grape juice as an alternative inexpensive bait for Anastrepha suspensa Loew, high numbers of Zaprionus indianus Gupta were captured in traps baited with aqueous grape juice. These experiments included comparisons of grape juice with standard...

  4. "Trap Setting" in Didactic Materials.

    ERIC Educational Resources Information Center

    Urdal, Pamela

    1984-01-01

    Trap setting is a concept based on a psycholinguistic explanation of the acquisition of second language skills emphasizing cognitive and creative processes over the auditory, visual, and imitative. It proposes that opportunities for repeated attempts at solving new problems through constant testing and retesting of creative hypotheses bring the…

  5. A Death Trap for Microglia.

    PubMed

    Du, Xu-Fei; Du, Jiu-Lin

    2016-07-25

    Microglia, immune cells of the brain, originate from erythromyeloid precursors, far from the central nervous system. Xu et al. (2016) in this issue of Developmental Cell and Casano et al. (2016) recently in Cell Reports show that apoptotic neurons act as bait to "trap" microglia into colonizing the developing brain. PMID:27459061

  6. Level structure and reflection asymmetric shape in sup 223 Ac

    SciTech Connect

    Sheline, R.K.; Liang, C.F.; Paris, P. )

    1990-07-20

    Mass separated sources of {sup 227}Pa (separated as PaF{sub 4}{sup +} ions) were used to study the level structure of {sup 223}Ac following alpha decay. The levels in {sup 223}Ac are interpreted as K = 5/2{sup {plus minus}} parity doublet bands which occur naturally in reflection asymmetric models and the multiphonon octupole model. The anomalous structure of the K = 3/2{sup {minus}} band is explained in terms of Coriolis coupling. The low lying parity doublet bands in {sup 223}Ac, {sup 225}Ac, and {sup 227}Ac are compared and contrasted.

  7. Characterization of photoactivated singlet oxygen damage in single-molecule optical trap experiments.

    PubMed

    Landry, Markita P; McCall, Patrick M; Qi, Zhi; Chemla, Yann R

    2009-10-21

    Optical traps or "tweezers" use high-power, near-infrared laser beams to manipulate and apply forces to biological systems, ranging from individual molecules to cells. Although previous studies have established that optical tweezers induce photodamage in live cells, the effects of trap irradiation have yet to be examined in vitro, at the single-molecule level. In this study, we investigate trap-induced damage in a simple system consisting of DNA molecules tethered between optically trapped polystyrene microspheres. We show that exposure to the trapping light affects the lifetime of the tethers, the efficiency with which they can be formed, and their structure. Moreover, we establish that these irreversible effects are caused by oxidative damage from singlet oxygen. This reactive state of molecular oxygen is generated locally by the optical traps in the presence of a sensitizer, which we identify as the trapped polystyrene microspheres. Trap-induced oxidative damage can be reduced greatly by working under anaerobic conditions, using additives that quench singlet oxygen, or trapping microspheres lacking the sensitizers necessary for singlet state photoexcitation. Our findings are relevant to a broad range of trap-based single-molecule experiments-the most common biological application of optical tweezers-and may guide the development of more robust experimental protocols.

  8. High voltage trapping effects in GaN-based metal-insulator-semiconductor transistors

    NASA Astrophysics Data System (ADS)

    Meneghesso, Gaudenzio; Meneghini, Matteo; Silvestri, Riccardo; Vanmeerbeek, Piet; Moens, Peter; Zanoni, Enrico

    2016-01-01

    This paper presents an analysis of the high voltage trapping processes that take place in high-electron mobility transistors based on GaN, with a metal-insulator-semiconductor (MIS) structure. The study is based on combined pulsed and transient measurements, carried out with trapping voltages in the range from 50 to 500 V. The results indicate that: (i) dynamic Ron is maximum for trapping voltages between 200 and 300 V, and decreases for higher voltage levels; (ii) Ron-transient measurements reveal the presence of a dominant trap with activation energy Ea1 = 0.93 eV and of a second trap with activation energy equal to Ea2 = 0.61 eV; (iii) the deep level transient spectroscopy (DLTS) signal associated to trap Ea1 is completely suppressed for high trapping voltages (VDS = 500 V). The results are interpreted by considering that the trap Ea1 is located in the buffer, and originates from CN defects. The exposure to high drain voltages may favor the depletion of such traps, due to a field-assisted de-trapping process or to the presence of vertical leakage paths.

  9. Funnel traps capture a higher proportion of juvenile Great Tits Parus major than automatic traps

    USGS Publications Warehouse

    Senar, J.C.; Domenech, J.; Conroy, M.J.

    1999-01-01

    We compared capture rates of Great Tits at funnel traps, where several birds can be captured at once so that some decoy effect may appear, to those obtained at automatic traps, where only one bird can be trapped at a time, at trapping stations in northeastern Spain. Juvenile birds were mainly captured at funnel traps (79% of juvenile captures), whereas adult plumaged birds were captured at both types of traps (51% of captures were at the funnel traps) (test between ages, P<0.001). Juvenile Great Tits had lower body condition as measured by ptilochronology (P<0.01). These birds are more easily trapped in funnel traps, which may be acting as decoy traps, and thus are vulnerable to the same kinds of biases (eg age or body condition) that have been previously documented for decoy traps.

  10. 50 CFR 697.19 - Trap limits and trap tag requirements for vessels fishing with lobster traps.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... vessels fishing with lobster traps. 697.19 Section 697.19 Wildlife and Fisheries FISHERY CONSERVATION AND... requirements for vessels fishing with lobster traps. (a) Trap limits for vessels fishing or authorized to fish... management area designation certificate or valid limited access American lobster permit specifying one...

  11. 50 CFR 697.19 - Trap limits and trap tag requirements for vessels fishing with lobster traps.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... vessels fishing with lobster traps. 697.19 Section 697.19 Wildlife and Fisheries FISHERY CONSERVATION AND... requirements for vessels fishing with lobster traps. (a) Trap limits for vessels fishing or authorized to fish... management area designation certificate or valid limited access American lobster permit specifying one...

  12. 50 CFR 697.19 - Trap limits and trap tag requirements for vessels fishing with lobster traps.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... vessels fishing with lobster traps. 697.19 Section 697.19 Wildlife and Fisheries FISHERY CONSERVATION AND... requirements for vessels fishing with lobster traps. (a) Trap limits for vessels fishing or authorized to fish... management area designation certificate or valid limited access American lobster permit specifying one...

  13. 50 CFR 697.19 - Trap limits and trap tag requirements for vessels fishing with lobster traps.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... vessels fishing with lobster traps. 697.19 Section 697.19 Wildlife and Fisheries FISHERY CONSERVATION AND... requirements for vessels fishing with lobster traps. (a) Trap limits for vessels fishing or authorized to fish... management area designation certificate or valid limited access American lobster permit specifying one...

  14. Application of spin traps to biological systems.

    PubMed

    Rosen, G M; Cohen, M S; Britigan, B E; Pou, S

    1990-01-01

    Since 1971, when nitroxides were first reported to be bioreduced, several cellular enzymes, in addition to ascorbic acid, have been found to catalyze the reduction of nitroxides to their corresponding hydroxylamines. Numerous studies have demonstrated that cellular bioreduction of nitroxides are both dependent upon the structure of the nitroxide and cell type. For example, pyrrolidinyloxyls are considerably more resistant to bioreduction than their corresponding piperidinyloxyls. In addition, cellular levels of reductases present in freshly isolated rat hepatocytes are considerably greater than concentrations found in freshly isolated rat enterocytes. Thus, through the proper selection of a cell type and an appropriate nitroxide, one can study cellular-mediated free radical processes. With the discovery that alpha-hydrogen-containing nitroxides, including 2,2-dimethyl-5-hydroxy-1-pyrrolidinyloxyl (DMPO-OH) decompose rapidly in the presence of superoxide and thiols, the ability to determine if hydroxyl radical is generated during stimulation of human neutrophils, is in doubt. To explore the limits of spin trapping in this context, we have studied the effect of varying the rates of superoxide production, in the presence and absence of thiols, on the decomposition of DMPO-OH. In parallel studies, we have found that t-butyl alpha-methyl-4-pyridinyl-N-oxide nitroxide (4-POBN-CH3) will not degrade in the presence of superoxide and a thiol. From these studies, we have determined that if hydroxyl radicals were generated as an isolated event in the presence of a continual flow of superoxide, spin trapping might not be able to detect its formation. Otherwise, spin trapping should be able to measure hydroxyl radicals, if continually generated, during activation of human neutrophils. PMID:2167256

  15. Finite-Size and Confinement Effects in Spin-Polarized Trapped Fermi Gases

    SciTech Connect

    Ku, Mark; Braun, Jens; Schwenk, Achim

    2009-06-26

    We calculate the energy of a single fermion interacting resonantly with a Fermi sea of different-species fermions in anisotropic traps, and show that finite particle numbers and the trap geometry impact the phase structure and the critical polarization. Our findings contribute to understanding some experimental discrepancies in spin-polarized Fermi gases as finite-size and confinement effects.

  16. Phonon Trapping in Pearl-Necklace-Shaped Silicon Nanowires.

    PubMed

    Miao, Chunyang; Tai, Guoan; Zhou, Jianxin; Guo, Wanlin

    2015-12-22

    A pearl-necklace-shaped silicon nanowire, in contrast to a smooth nanowire, presents a much lower thermal conductivity due to the phonon trapping effect. By precisely controlling the pearl size and density, this reduction can be more than 70% for the structures designed in the study, which provides a unique approach for designing high-performance nanoscale thermoelectric devices. PMID:26577864

  17. Phonon Trapping in Pearl-Necklace-Shaped Silicon Nanowires.

    PubMed

    Miao, Chunyang; Tai, Guoan; Zhou, Jianxin; Guo, Wanlin

    2015-12-22

    A pearl-necklace-shaped silicon nanowire, in contrast to a smooth nanowire, presents a much lower thermal conductivity due to the phonon trapping effect. By precisely controlling the pearl size and density, this reduction can be more than 70% for the structures designed in the study, which provides a unique approach for designing high-performance nanoscale thermoelectric devices.

  18. Optical and Magnetic Trapping of Potassium 39

    NASA Astrophysics Data System (ADS)

    Ensher, Jason; Cornell, Eric; Cataliotti, Francesco; Fort, Chiara; Marin, Francesco; Prevedelli, Marco; Inguscio, Massimo; Ricci, Leonardo; Tino, Guglielmo

    1998-05-01

    We present measurments of optical trapping and cooling and magnetic trapping of ^39K in a double-MOT apparatus. (Optics Lett. 21, 290(1996)) We have measured light-assisted collisional loss rates from our second MOT over a range of trap light intensities. At an intensity of 10 mW/cm^2 we find a loss rate parameter β of 2 x 10-11 cc/s. β increases with trap light intensity and is consistent with the values measured by Williamson and Walker (JOSA B 12, 1393 (1995)). We also present studies of the temperature of atoms in a MOT of ^39K. Under certain conditions of repump light intensity and trap light detuning we measure temperatures nearly as low as the Doppler Limit. Finally, we report on prelimiary results of magnetic trapping in which we have trapped several 10^7 atoms in a quadrupole magnetic trap.

  19. Stokes Trap: Multiplexed particle trapping and manipulation using fluidics

    NASA Astrophysics Data System (ADS)

    Shenoy, Anish; Schroeder, Charles

    We report the development of the Stokes Trap, which is a multiplexed microfluidic trap for control over an arbitrary number of small particles in a microfluidic device. Our work involves the design and implementation of ``smart'' flow-based devices by coupling feedback control with microfluidics, thereby enabling new routes for the fluidic-directed assembly of particles. Here, we discuss the development of a new method to achieve multiplexed microfluidic trapping of an arbitrary number of particles using the sole action of fluid flow. In particular, we use a Hele-Shaw microfluidic cell to generate hydrodynamic forces on particles in a viscous-dominated flow defined by the microdevice geometry and imposed peripheral flow rates. This platform allows for a high degree of flow control over individual particles and can be used for manufacturing novel particles for fundamental studies, using fluidic-directed assembly. From a broader perspective, our work provides a solid framework for guiding the design of next-generation, automated on-chip assays.

  20. Geomagnetically trapped energetic helium nuclei

    SciTech Connect

    Chen, J.; Gregory Guzik, T.; Wefel, J.P.; Roger Pyle, K.; Cooper, J.F.

    1996-07-01

    Geomagnetically trapped helium nuclei, at high energy ({approximately}40{endash}100 MeV/nucleon), have been measured by the ONR-604 instrument during the 1990/1991 CRRES mission. The ONR-604 instrument resolved the isotopes of helium with a mass resolution of 0.1 amu. The energetic helium observed at {ital L}{lt}2.3 have a pitch angle distribution peaking perpendicular to the local magnetic field, which is characteristic of a trapped population. Both the trapped {sup 3}He and {sup 4}He show two peaks at {ital L}=1.2 and 1.9. Each isotope{close_quote}s flux, in each peak, can be characterized by a power law energy spectrum. The energy spectrum of the {sup 3}He is different from that of {sup 4}He, indicating that the {sup 3}He/{sup 4}He ratio is energy dependent. Over the energy range of 51{endash}86 MeV/nucleon, the {sup 3}He/{sup 4}He ratio is 8.7{plus_minus}3.1 at {ital L}=1.1{endash}1.5 and is 2.4{plus_minus}0.6 at {ital L}=1.5{endash}2.3. The trapped helium counting rates decrease gradually with time during the CRRES mission, when the anomalous component is excluded from the inner heliosphere, indicating that these high energy ions were not injected by flares during this time period. The decrease in intensity is attributed mainly to the events around {ital L}=1.9. The helium around {ital L}=1.2, dominated by {sup 3}He, does not show a significant temporal evolution, which implies a long-term energetic trapped {sup 3}He population. Two possible origins of the geomagnetically trapped helium isotopes are the interactions of energetic protons with the upper atmosphere and/or the inward diffusion and acceleration of helium ions due to electric-field fluctuations. {copyright} {ital 1996 American Institute of Physics.}

  1. Survival Probabilities in Coherent Exciton Transfer with Trapping

    SciTech Connect

    Muelken, Oliver; Blumen, Alexander; Amthor, Thomas; Giese, Christian; Reetz-Lamour, Markus; Weidemueller, Matthias

    2007-08-31

    In the quest for signatures of coherent transport we consider exciton trapping in the continuous-time quantum walk framework. The survival probability displays different decay domains, related to distinct regions of the spectrum of the Hamiltonian. For linear systems and at intermediate times the decay obeys a power law, in contrast with the corresponding exponential decay found in incoherent continuous-time random walk situations. To differentiate between the coherent and incoherent mechanisms, we present an experimental protocol based on a frozen Rydberg gas structured by optical dipole traps.

  2. An innovative mosquito trap for testing attractants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We describe a simple trap modification for testing or using attractants to collect flying mosquitoes. The trap also can test the effectiveness of spatial repellents. The proposed design may facilitate standardized testing of mosquito attractants and repellents. The trap uses a standard Centers f...

  3. 50 CFR 697.27 - Trap transferability.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Measures § 697.27 Trap transferability. (a) Federal lobster permit holders may elect to participate in a program that allows them to transfer trap allocation to other participating Federal lobster permit holders... Federal Trap Transfer Program: (i) An individual must possess a valid Federal lobster permit; and (ii)...

  4. Trapping models for the Lower Silurian Medina Sandstone Group - A comparison of trapping styles and exploration methodology for both deep and shallow medina plays in the Appalachian basin

    SciTech Connect

    Zagorski, W.A. )

    1991-08-01

    The Lower Silurian Medina Sandstone Group has been a major oil and gas producer in the Appalachian basin since the late 1800s and remains a primary objective in parts of New York, Ohio, and Pennsylvania. Although classified as a stratigraphic trap, production from the Medina is obtained from a wide variety of trapping conditions ranging from pure stratigraphic to structural stratigraphic in the shallower producing areas of the Medina to deep basin (i.e., Elmworth field, western Canada) trapping in the deeper producing regions of strategies must be employed for optimum prospect development and maximum economic success ratios. Several producing areas of the Medina are presented to compare and contrast these various trapping mechanisms together with suggested exploration models applicable to each trap type.

  5. Atom Trap, Krypton-81, and Saharan Water

    SciTech Connect

    Lu, Zheng-Tian

    2005-08-24

    Since radiocarbon dating was first demonstrated in 1949, the field of trace analyses of long-lived cosmogenic isotopes has seen steady growth in both analytical methods and applicable isotopes. The impact of such analyses has reached a wide range of scientific and technological areas. A new method, named Atom Trap Trace Analysis (ATTA), was developed by our group and used to analyze {sup 81}Kr (t{sub 1/2} = 2.3 x 10{sup 5} years, isotopic abundance {approx} 1 x 10{sup -12}) in environmental samples. In this method, individual {sup 81}Kr atoms are selectively captured and detected with a laser-based atom trap. {sup 81}Kr is produced by cosmic rays in the upper atmosphere. It is the ideal tracer for dating ice and groundwater in the age range of 10{sup 4}-10{sup 6} years. As the first real-world application of ATTA, we have determined the mean residence time of the old groundwater in the Nubian Aquifer located underneath the Sahara Desert. Moreover, this method of capturing and probing atoms of rare isotopes is also applied to experiments that study exotic nuclear structure and test fundamental symmetries.

  6. Ground states of trapped spin-1 condensates in magnetic field

    SciTech Connect

    Matuszewski, Michal

    2010-11-15

    We consider a spin-1 Bose-Einstein condensate trapped in a harmonic potential under the influence of a homogeneous magnetic field. We investigate spatial and spin structure of the mean-field ground states under constraints on the number of atoms and the total magnetization. We show that the trapping potential can make the antiferromagnetic condensate separate into three distinct phases and ferromagnetic condensate into two distinct phases. In the ferromagnetic case, the magnetization is located in the center of the harmonic trap, while in the antiferromagnetic case magnetized phases appear in the outer regions. We describe how the transition from the Thomas-Fermi regime to the single-mode approximation regime with decreasing number of atoms results in the disappearance of the domains. We suggest that the ground states can be created in experiment by adiabatically changing the magnetic-field strength.

  7. Towards a 3-D Magneto-Optical Trap for Molecules

    NASA Astrophysics Data System (ADS)

    Collopy, Alejandra; Hummon, Matthew; Yeo, Mark; Stuhl, Benjamin; Hemmerling, Boerge; Drayna, Garrett; Chae, Eunmi; Ravi, Aakash; Lu, Hsin-I.; Doyle, John; Ye, Jun

    2013-05-01

    As the magneto-optical trap revolutionized atomic physics, we anticipate the molecular counterpart to open doors to unexplored molecular physics, including ultra-cold chemistry. While molecules possess more complex structure than atoms, quasi-cycling cooling transitions are still attainable in a variety of species, including the polar molecule YO. In order to remix dark states, we RF modulate the polarization of the light in our trap. In order to maintain a restoring force, we modulate the orientation of our magnetic fields in phase with the light using LC resonant in-vacuum magnetic coils. We demonstrate magneto-optical trapping in two dimensions for YO, and present progress towards a three dimensional implementation of a MOT loaded from a two-stage buffer gas cell source. We acknowledge support from the AFOSR (MURI), DOE, NIST and the NSF.

  8. Microscale ion trap mass spectrometer

    DOEpatents

    Ramsey, J. Michael; Witten, William B.; Kornienko, Oleg

    2002-01-01

    An ion trap for mass spectrometric chemical analysis of ions is delineated. The ion trap includes a central electrode having an aperture; a pair of insulators, each having an aperture; a pair of end cap electrodes, each having an aperture; a first electronic signal source coupled to the central electrode; a second electronic signal source coupled to the end cap electrodes. The central electrode, insulators, and end cap electrodes are united in a sandwich construction where their respective apertures are coaxially aligned and symmetric about an axis to form a partially enclosed cavity having an effective radius r.sub.0 and an effective length 2z.sub.0, wherein r.sub.0 and/or z.sub.0 are less than 1.0 mm, and a ratio z.sub.0 /r.sub.0 is greater than 0.83.

  9. Trapping and spectroscopy of hydrogen

    NASA Astrophysics Data System (ADS)

    Cesar, Claudio Lenz

    1997-08-01

    I review the results and techniques used by the MIT H↑ group to achieve a fractional resolution of 2 parts in 1012 in the 1S-2S transition in hydrogen [Cesar, D. Fried, T. Killian, A. Polcyn, J. Sandberg, I.A. Yu, T. Greytak, D. Kleppner and J. Doyle, Two-photon spectroscopy of trapped atomic hydrogen, Phys. Rev. Lett. 77 (1996) 255.] With some improvements, this system should deliver 100 times higher resolution with an improved signal count rate getting us closer to an old advertised goal of a precision of 1 part in 1018. While these developments are very important for the proposed test of the CPT theorem through the comparison with anti-hydrogen, some of the techniques used with hydrogen are not applicable to anti-hydrogen and I discuss some difficulties and alternatives for the trapping and spectroscopy of anti-hydrogen.

  10. Centrifugal trapping in the magnetotail

    NASA Technical Reports Server (NTRS)

    Delcourt, D. C.; Martin, R. F., Jr.; Sauvaud, J. A.; Moore, T. E.

    1995-01-01

    Particles leving the neutral sheet in the distant magnetotail at times display adiabatic trajectory sequences characterized by an inflection toward the equator and subsequent mirroring in its vicinity. We demonstrate that this low-latitude mirroring results primarily from a centrifugal deceleration due to the fast direction-changing E x B drift. This effect which we refer to as 'centrifugal trapping' appears both in guiding centre and full particle treatments. It thus does not directly relate to nonadiabatic motion. However, pitch angle scattering due to nonadiabatic neutral sheet interaction does play a role in reducing the parallel speed of the particles. We show that centrifugal trapping is an important mechanism for the confinement of the slowest (typically below the equatorial E x B drift speed) plasma sheet populations to the midplane vicinity.

  11. Plasmon assisted optical trapping: fundamentals and biomedical applications

    NASA Astrophysics Data System (ADS)

    Serafetinides, Alexandros A.; Makropoulou, Mersini; Tsigaridas, Georgios N.; Gousetis, Anastasios

    2015-01-01

    The field of optical trapping has dramatically grown due to implementation in various arenas including physics, biology, medicine and nanotechnology. Certainly, optical tweezers are an invaluable tool to manipulate a variation of particles, such as small dielectric spheres, cells, bacteria, chromosomes and even genes, by highly focused laser beams through microscope. As the main disadvantage of the conventional optical trapping systems is the diffraction limit of the incident light, plasmon assisted nanotrapping is reported as a suitable technique for trapping sub-wavelength metallic or dielectric particles. In this work, firstly, we report briefly on the basic theory of plasmon excitation, focusing on the interaction of nanoscale metallic structures with laser light. Secondly, experimental and numerical simulation results are also presented, demonstrating enhancement of the trapping efficiency of glass or SiO2 substrates, coated with Au and Ag nanostructures, with or without nanoparticles. The optical forces were calculated by measuring the particle's escape velocity calibration method. Finally, representative applications of plasmon assisted optical trapping are reviewed, from cancer therapeutics to fundamental biology and cell nanosurgery.

  12. Autoenhanced Raman Spectroscopy via Plasmonic Trapping for Molecular Sensing.

    PubMed

    Hong, Soonwoo; Shim, On; Kwon, Hyosung; Choi, Yeonho

    2016-08-01

    As a label-free and sensitive biosensor, surface-enhanced Raman spectroscopy (SERS) is a rapidly emerging technique. However, because SERS spectra are obtained in the area of light excitation and the enhancement effect can be varied depending on the position of a substrate, it is important to match the enhanced area with an illuminated spot. Here, in order to overcome such difficulty, we demonstrated a new technique combining SERS with plasmonic trapping. By plasmonic trapping, we can collect gold nanoparticles (GNPs) in the middle of initially fabricated nanobowtie structures where a laser is excited. As a result of trapping GNPs, hot-spots are formed at that area. Because SERS is measured in the area irradiated by a laser, hot-spot can be simultaneously coincided with a detection site for SERS. By using this, we detected Rhodamine 6G to 100 pM. To further verify and improve the reproducibility of our technique, we also calculated the electric field distribution, trapping force and trapping potential. PMID:27396542

  13. Laser cooling, trapping, and Rydberg spectroscopy of neutral holmium atoms

    NASA Astrophysics Data System (ADS)

    Hostetter, James Allen

    This thesis focuses on progress towards using ensembles of neutral holmium for use in quantum computing operations. We are particularly interested in using a switchable interaction between neutral atoms, the Rydberg blockade, to implement a universal set of quantum gates in a collective encoding scheme that presents many benefits over quantum computing schemes which rely on physically distinct qubits. We show that holmium is uniquely suited for operations in a collective encoding basis because it has 128 ground hyperfine states, the largest number of any stable, neutral atom. Holmium is a rare earth atom that is very poorly described for our purposes as it has never been cooled and trapped, its spectrum is largely unknown, and it presents several unique experimental challenges related to its complicated atomic structure and short wavelength transitions. We demonstrate important progress towards overcoming these challenges. We produce the first laser cooling and trapping of holmium into a MOT. Because we use a broad cooling transition, our cooling technique does not require the use of a Zeeman slower. Using MOT depletion spectroscopy, we provide precise measurements of holmium's Rydberg states and its ionization potential. Our work continues towards cooling holmium into a dipole trap by calculating holmium's AC polarizability and demonstrating the results of early attempts at an optical dipole trap. We provide details of future upgrades to the experimental apparatus and discuss interesting potential for using holmium in quantum computing using single atoms in a magnetically trapped lattice. This thesis shows several promising indicators for continued work in this field.

  14. Trapper readies trap for lizard

    NASA Technical Reports Server (NTRS)

    2000-01-01

    State-licensed animal trapper James Dean sets the open door of an animal trap on KSC. He hopes to catch a large monitor lizard spotted recently near S.R. 3, a route into the Center, by several area residents. The lizard is not a native of the area, and possibly a released pet. Dean is working with the cooperation of KSC and the Merritt Island National Wildlife Refuge.

  15. Trapped noble gases in meteorites

    NASA Technical Reports Server (NTRS)

    Swindle, Timothy D.

    1988-01-01

    The trapped noble gases in meteorites come in two main varieties, usually referred to as solar and planetary. The solar noble gases are implanted solar-wind or solar-flare materials, and thus their relative elemental abundances provide a good estimate of those of the sun. The planetary noble gases have relative elemental abundances similar to those in the terrestrial atmosphere, but there are also important distinctions. At least one other elemental pattern (subsolar) and several isotopic patterns have also been identified.

  16. Optical trapping inside living organisms

    NASA Astrophysics Data System (ADS)

    Hansen, Poul M.; Oddershede, Lene B.

    2005-08-01

    We use optical tweezers to investigate processes happening inside ving cells. In a previous study, we trapped naturally occurring lipid granules inside living yeast cells, and used them to probe the viscoelastic properties of the cytoplasm. However, we prefer to use probes which can be specifically attached to various organelles within the living cells in order to optically quantify the forces acting on these organelles. Therefore, we have chosen to use nanometer sized gold beads as probes. These gold beads can be conjugated and attached chemically to the organelles of interest. Only Rayleigh metallic particles can be optically trapped and for these it is the case that the larger the beads, the larger the forces which can be exerted and thus measured using optical tweezers. The gold nanoparticles are injected into the cytoplasm using micropipettes. The very rigid cell wall of the S. pombe yeast cells poses a serious obstacle to this injection. In order to be able to punch a hole in the cell, first, the cells have to be turned into protoplasts, where only a lipid bilayer separates the cytoplasm from the surrounding media. We show how to perform micropipette delivery into the protoplasts and also how the protoplasts can be ablated using the trapping laserlight. Finally, we demonstrate that we can transform the protoplasts back to normal yeast cells.

  17. Simple analytic potentials for linear ion traps

    NASA Technical Reports Server (NTRS)

    Janik, G. R.; Prestage, J. D.; Maleki, L.

    1990-01-01

    A simple analytical model was developed for the electric and ponderomotive (trapping) potentials in linear ion traps. This model was used to calculate the required voltage drive to a mercury trap, and the result compares well with experiments. The model gives a detailed picture of the geometric shape of the trapping potential and allows an accurate calculation of the well depth. The simplicity of the model allowed an investigation of related, more exotic trap designs which may have advantages in light-collection efficiency.

  18. New ion trap for frequency standard applications

    NASA Technical Reports Server (NTRS)

    Prestage, J. D.; Dick, G. J.; Maleki, L.

    1989-01-01

    A novel linear ion trap was designed, which permits storage of a large number of ions with reduced susceptibility to the second-order Doppler effect caused by the RF confining fields. This new trap should store about 20 times the number of ions as a conventional RF trap with no corresponding increase in second-order Doppler shift from the confining field. In addition, the sensitivity of this shift to trapping parameters, i.e., RF voltage, RF frequency, and trap size, is greatly reduced.

  19. Simple analytic potentials for linear ion traps

    NASA Technical Reports Server (NTRS)

    Janik, G. R.; Prestage, J. D.; Maleki, L.

    1989-01-01

    A simple analytical model was developed for the electric and ponderomotive (trapping) potentials in linear ion traps. This model was used to calculate the required voltage drive to a mercury trap, and the result compares well with experiments. The model gives a detailed picture of the geometric shape of the trapping potenital and allows an accurate calculation of the well depth. The simplicity of the model allowed an investigation of related, more exotic trap designs which may have advantages in light-collection efficiency.

  20. Nonadiabatic transitions in electrostatically trapped ammonia molecules

    SciTech Connect

    Kirste, Moritz; Schnell, Melanie; Meijer, Gerard; Sartakov, Boris G.

    2009-05-15

    Nonadiabatic transitions are known to be major loss channels for atoms in magnetic traps but have thus far not been experimentally reported upon for trapped molecules. We have observed and quantified losses due to nonadiabatic transitions for three isotopologues of ammonia in electrostatic traps by comparing the trapping times in traps with a zero and a nonzero electric field at the center. Nonadiabatic transitions are seen to dominate the overall loss rate even for the present samples that are at relatively high temperatures of 30 mK. It is anticipated that losses due to nonadiabatic transitions in electric fields are omnipresent in ongoing experiments on cold molecules.