Sample records for processes trapping mechanisms

  1. Trapped Atomic Ions and Quantum Information Processing

    SciTech Connect

    Wineland, D. J.; Leibfried, D.; Bergquist, J. C.; Blakestad, R. B.; Bollinger, J. J.; Britton, J.; Chiaverini, J.; Epstein, R. J.; Hume, D. B.; Itano, W. M.; Jost, J. D.; Koelemeij, J. C. J.; Langer, C.; Ozeri, R.; Reichle, R.; Rosenband, T.; Schaetz, T.; Schmidt, P. O.; Seidelin, S.; Shiga, N. [Time and Frequency Division, NIST, Boulder, CO (United States)] (and others)

    2006-11-07

    The basic requirements for quantum computing and quantum simulation (single- and multi-qubit gates, long memory times, etc.) have been demonstrated in separate experiments on trapped ions. Construction of a large-scale information processor will require synthesis of these elements and implementation of high-fidelity operations on a very large number of qubits. This is still well in the future. NIST and other groups are addressing part of the scaling issue by trying to fabricate multi-zone arrays of traps that would allow highly-parallel and scalable processing. In the near term, some simple quantum processing protocols are being used to aid in quantum metrology, such as in atomic clocks. As the number of qubits increases, Schroedinger's cat paradox and the measurement problem in quantum mechanics become more apparent; with luck, trapped ion systems might be able to shed light on these fundamental issues.

  2. 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 [School of Physics and Optoelectronic Engineering, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian 116024 (China); Jiang, Xuening; Zhang, Jialiang [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian 116024 (China)

    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.

  3. Mixtures of Charged Bosons Confined in Harmonic Traps and Bose-Einstein Condensation Mechanism for Low-Energy Nuclear Reactions and Transmutation Processes in Condensed Matters

    NASA Astrophysics Data System (ADS)

    Kim, Yeong E.; Zubarev, Alexander L.

    2006-02-01

    A mixture of two different species of positively charged bosons in harmonic traps is considered in the mean-field approximation. It is shown that depending on the ratio of parameters, the two components may coexist in same regions of space, in spite of the Coulomb repulsion between the two species. Application of this result is discussed for the generalization of the Bose-Einstein condensation mechanism for low-energy nuclear reaction (LENR) and transmutation processes in condensed matters. For the case of deutron-lithium (d + Li) LENR, the result indicates that (d + 6Li) reactions may dominate over (d + d) reactions in LENR experiments.

  4. Physical process Mechanical mechanisms

    E-print Network

    Berlin,Technische Universität

    1 Physical process Generation · Mechanical mechanisms F = m·a · Electric/Magnetic mechanisms F = B·i·l · Fluid dynamic/Hydraulic mechanisms q, p, ij · Thermal/Optical #12;2 Source unit and source mechanisms ­ Monopoles......volume fluctuations ­ Dipoles ......pressure fluctuations

  5. Unification of three multiphonon trap-assisted tunneling mechanisms

    NASA Astrophysics Data System (ADS)

    Zhang, Manhong; Huo, Zongliang; Yu, Zhaoan; Liu, Jing; Liu, Ming

    2011-12-01

    There are three basic multiphonon trap-assisted tunneling (TAT) mechanisms in the gate leakage current of a metal-oxide-semiconductor (MOS) structure: the short-ranged trap potential, nonadiabatic interaction and electric field induced trap-band transitions. In this paper, a comparison of these three mechanisms is made for the first time in a single (Schenk's model) MOS structure. A properly box-normalized electron wave function in the SiO2 conduction band in an electric field is used to calculate the field ionization rate of a deep neutral trap. It is found that capture and emission rates of a deep neutral trap are almost the same in the short-ranged trap potential and nonadiabatic interaction induced TAT processes, so the two mechanisms give a similar contribution to the total TAT current. The calculated TAT current and the average relaxation energy (˜1.5 eV) due to these two mechanisms are in good agreement with the experimental results. In contrast, capture and emission rates in Schenk's model are several orders smaller. The TAT current induced by this mechanism is also much smaller and can be ignored.

  6. Molten Hydroxide Trapping Process for Radioiodine

    SciTech Connect

    Trowbridge, L.D.

    2003-01-28

    A molten hydroxide trapping process has been considered for removing radioiodine species from off-gas streams whereby iodine is reacted directly with molten hydroxides such as NaOH or KOH. The resulting product is the corresponding iodide, which can be separated by simple cooling of the molten mixture to grow the iodide primary phase once the mixture reaches 70-80 mol% in the iodide component. Thermodynamic analysis indicates that such a chemical process is highly favorable. Experimental testing of the trapping process using molecular iodine showed trapping of up to 96% of the volatile iodine. The trapping efficiency was dependent on operational parameters such as temperature and gas-melt contact efficiency, and higher efficiencies are expected as the process is further developed. While an iodide phase could be effectively isolated by slow cooling of a molten iodide-hydroxide mixture, the persistent appearance of hydroxide indicated that an appreciable solubility of hydroxide occurred in the iodide phase.

  7. Quantum mechanics in rotating-radio-frequency traps and Penning traps with a quadrupole rotating field

    SciTech Connect

    Abe, K.; Hasegawa, T. [Department of Physics, Keio University, Kanagawa 223-8522 (Japan)

    2010-03-15

    Quantum-mechanical analysis of ion motion in a rotating-radio-frequency (rrf) trap or in a Penning trap with a quadrupole rotating field is carried out. Rrf traps were introduced by Hasegawa and Bollinger [Phys. Rev. A 72, 043404 (2005)]. The classical motion of a single ion in this trap is described by only trigonometric functions, whereas in the conventional linear radio-frequency (rf) traps it is by the Mathieu functions. Because of the simple classical motion in the rrf trap, it is expected that the quantum-mechanical analysis of the rrf traps is also simple compared to that of the linear rf traps. The analysis of Penning traps with a quadrupole rotating field is also possible in a way similar to the rrf traps. As a result, the Hamiltonian in these traps is the same as the two-dimensional harmonic oscillator, and energy levels and wave functions are derived as exact results. In these traps, it is found that one of the vibrational modes in the rotating frame can have negative energy levels, which means that the zero-quantum-number state (''ground'' state) is the highest energy state.

  8. Current drive via autoresonance and intermittent trapping mechanisms. S. Louies, D. Carati,

    E-print Network

    . It was found that, due to the non-linear interaction of the two waves, a travelling ponderomotive well) acceleration mechanism proposed by Davydovskii and Kolomenskii and Lebedev [1] for driving currents was generated allowing for trapping the electrons. This trapping process may condition the particles for going

  9. Hydrogen-Trapping Mechanisms in Nanostructured Steels

    NASA Astrophysics Data System (ADS)

    Szost, B. A.; Vegter, R. H.; Rivera-Díaz-del-Castillo, Pedro E. J.

    2013-10-01

    Nanoprecipitation-hardened martensitic bearing steels (100Cr6) and carbide-free nanobainitic steels (superbainite) are examined. The nature of the hydrogen traps present in both is determined via the melt extraction and thermal desorption analysis techniques. It is demonstrated that 100Cr6 can admit large amounts of hydrogen, which is loosely bound to dislocations around room temperature; however, with the precipitation of fine coherent vanadium carbide traps, hydrogen can be immobilized. In the case of carbide-free nanostructured bainite, retained austenite/bainite interfaces act as hydrogen traps, while concomitantly retained austenite limits hydrogen absorption. In nanostructured steels where active hydrogen traps are present, it is shown that the total hydrogen absorbed is proportional to the trapped hydrogen, indicating that melt extraction may be employed to quantify trapping capacity.

  10. Conversion of liquid-nitrogen traps to mechanical refrigeration

    NASA Astrophysics Data System (ADS)

    Coggiola, M. J.; Leon, R. L.; Scally, R. L.

    1983-07-01

    A simple technique is described which allows a reservoir-type liquid-nitrogen trap to be converted to continuous operation with a closed-cycle mechanical refrigeration system. The conversion requires no internal modification to the trap and uses only standard commercial refrigeration components. Using 502 refrigerant as the working fluid, temperatures of -52 °C are readily achieved in a trap operating above a 6-in. water-cooled baffle and oil diffusion pump.

  11. Quantum information processing with trapped ion chains

    NASA Astrophysics Data System (ADS)

    Manning, Timothy Andrew

    Trapped atomic ion systems are currently the most advanced platform for quantum information processing. Their long coherence times, pristine state initialization and detection, and precisely controllable and versatile interactions make them excellent quantum systems for experiments in quantum computation and quantum simulation. One of the more promising schemes for quantum computing consists of performing single and multi-qubit quantum gates on qubits in a linear ion crystal. Some of the key challenges of scaling such a system are the individual addressing of arbitrary subsets of ions and controlling the growing complexity of motional mode interactions as the number of qubits increases or when the gates are performed faster. Traditional entangling quantum gates between ion qubits use laser pulses to couple the qubit states to the collective motion of the crystal, thereby generating a spin-spin interaction that can produce entanglement between selected qubits. The intrinsic limitations on the performance of gates using this method can be alleviated by applying optimally shaped pulses instead of pulses with constant amplitude. This thesis explains the theory behind this pulse shaping scheme and how it is implemented on a chain of Yb ions held in a linear radiofrequency 'Paul' trap. Several experiments demonstrate the technique in chains of two, three, and five ions using various types of pulse shapes. A tightly focused individual addressing beam allows us to apply the entangling gates to a target pair of ions, and technical issues related to such tight focusing are discussed. Other advantages to the pulse shaping scheme include a robustness against detuning errors and the possibility of suppressing undesirable coupling due to optical spillover on neighboring ions. Combined with ion shuttling, we harness these features to perform sequential gates to different qubit pairs in order to create genuine tripartite entangled states and demonstrate the programmable quantum information processing capability of our system.

  12. Mixtures of Charged Bosons Confined in Harmonic Traps and Bose-Einstein Condensation Mechanism for Low-Energy Nuclear Reactions and Transmutation Processes in Condensed Matters

    Microsoft Academic Search

    Yeong E. Kim; Alexander L. Zubarev

    2006-01-01

    A mixture of two different species of positively charged bosons in harmonic traps is considered in the mean-field approximation. It is shown that depending on the ratio of parameters, the two components may coexist in same regions of space, in spite of the Coulomb repulsion between the two species. Application of this result is discussed for the generalization of the

  13. Mixtures of Charged Bosons Confined in Harmonic Traps and Bose Einstein Condensation Mechanism for Low Energy Nuclear Reactions and Transmutation Processes in Condensed Matter

    Microsoft Academic Search

    Yeong E. Kim; Alexander L. Zubarev

    A mixture of two different species of positively charged bosons in harmonic traps is considered in the mean-field approximation. It is shown that depending on the ratio of parameters, the two components may coexist in same regions of space, in spite of the Coulomb repulsion between the two species. Application of this result is discussed for the generalization of the

  14. Mechanical Systems Signal Processing

    E-print Network

    Ray, Asok

    Mechanical Systems and Signal Processing Mechanical Systems and Signal Processing 21 (2007) 866 and analytical models. This paper attempts to address this inadequacy by taking advantage of advanced signal processing and pattern recognition tools. Since a vast majority of structural components that are prone

  15. Ion funnel ion trap and process

    DOEpatents

    Belov, Mikhail E [Richland, WA; Ibrahim, Yehia M [Richland, WA; Clowers, Biran H [West Richland, WA; Prior, David C [Hermiston, OR; Smith, Richard D [Richland, WA

    2011-02-15

    An ion funnel trap is described that includes a inlet portion, a trapping portion, and a outlet portion that couples, in normal operation, with an ion funnel. The ion trap operates efficiently at a pressure of .about.1 Torr and provides for: 1) removal of low mass-to-charge (m/z) ion species, 2) ion accumulation efficiency of up to 80%, 3) charge capacity of .about.10,000,000 elementary charges, 4) ion ejection time of 40 to 200 .mu.s, and 5) optimized variable ion accumulation times. Ion accumulation with low concentration peptide mixtures has shown an increase in analyte signal-to-noise ratios (SNR) of a factor of 30, and a greater than 10-fold improvement in SNR for multiply charged analytes.

  16. Rossby waves trapped by quantum mechanics Thierry Paul

    E-print Network

    Paris-Sud XI, Université de

    Rossby waves trapped by quantum mechanics Thierry Paul Rossby and Poincar´e waves appear naturally dispersive waves and are due to the rotation of the Earth through the Coriolis force. Much slower, Rossby type of waves: dispersion for Poincar´e and confining in x2 for Rossby. The method of proving Theorem 1

  17. Materials processing routes to trap-free halide perovskites.

    PubMed

    Buin, Andrei; Pietsch, Patrick; Xu, Jixian; Voznyy, Oleksandr; Ip, Alexander H; Comin, Riccardo; Sargent, Edward H

    2014-11-12

    Photovoltaic devices based on lead iodide perovskite films have seen rapid advancements, recently achieving an impressive 17.9% certified solar power conversion efficiency. Reports have consistently emphasized that the specific choice of growth conditions and chemical precursors is central to achieving superior performance from these materials; yet the roles and mechanisms underlying the selection of materials processing route is poorly understood. Here we show that films grown under iodine-rich conditions are prone to a high density of deep electronic traps (recombination centers), while the use of a chloride precursor avoids the formation of key defects (Pb atom substituted by I) responsible for short diffusion lengths and poor photovoltaic performance. Furthermore, the lowest-energy surfaces of perovskite crystals are found to be entirely trap-free, preserving both electron and hole delocalization to a remarkable degree, helping to account for explaining the success of polycrystalline perovskite films. We construct perovskite films from I-poor conditions using a lead acetate precursor, and our measurement of a long (600 ± 40 nm) diffusion length confirms this new picture of the importance of growth conditions. PMID:25296282

  18. Quantum information processing with trapped electrons and superconducting electronics

    E-print Network

    Nikos Daniilidis; Dylan J Gorman; Lin Tian; Hartmut Häffner

    2013-04-17

    We describe a parametric frequency conversion scheme for trapped charged particles which enables a coherent interface between atomic and solid-state quantum systems. The scheme uses geometric non-linearities of the potential of a coupling electrode near a trapped particle. Our scheme does not rely on actively driven solid-state devices, and is hence largely immune to noise in such devices. We present a toolbox which can be used to build electron-based quantum information processing platforms, as well as quantum interfaces between trapped electrons and superconducting electronics.

  19. Entanglement and Quantum Information Processing with Trapped Ions

    Microsoft Academic Search

    John Chiaverini

    2004-01-01

    Atomic ions confined in radio frequency traps, cooled and addressed with laser pulses, constitute a scalable system for bringing about and exploring quantum entanglement and information processing. Along with relatively high entangling-gate and single-qubit-rotation fidelities, long coherence times enable the execution of some basic quantum algorithms and communication protocols. At NIST we use a multi-zone trap in which entanglement can

  20. Integrated Microsystems Approach to Trapped Ion Quantum Information Processing

    NASA Astrophysics Data System (ADS)

    Kim, Jungsang

    2013-05-01

    Trapped atomic ions are the leading candidate physical system for quantum information processing, featuring high quality qubits capable of high fidelity operations including state preparation, detection and quantum logic gates. A major remaining challenge is the task of constructing experimental systems where all operations necessary for quantum information processing can be performed in a scalable way. I will discuss a three-tier approach to construct such scalable hardware utilizing technologies that are available today. Arbitrary qubit gate operations in a linear ion chain (<102 ions) can be realized with control beams that can address individual ions in the chain. Shuttling of ions between such chains enable qubit gates between several chains (~ 10 chains) implemented in a single chip trap. One can then connect a large number (~103) of such trap chips using reconfigurable photonic network. Complex microfabricated ion trap chips integrated with various optical components such as reflectors, lenses and optical cavities are crucial in realizing efficient interfaces for these experiments, and micromirrors can provide fast and flexible beam delivery system with individual addressing capability. I will present the progress in ion qubit manipulation on microfabricated chip traps, the integration effort with optical components, and potential application in scalable quantum computer and quantum repeater realization. Trapped atomic ions are the leading candidate physical system for quantum information processing, featuring high quality qubits capable of high fidelity operations including state preparation, detection and quantum logic gates. A major remaining challenge is the task of constructing experimental systems where all operations necessary for quantum information processing can be performed in a scalable way. I will discuss a three-tier approach to construct such scalable hardware utilizing technologies that are available today. Arbitrary qubit gate operations in a linear ion chain (<102 ions) can be realized with control beams that can address individual ions in the chain. Shuttling of ions between such chains enable qubit gates between several chains (~ 10 chains) implemented in a single chip trap. One can then connect a large number (~103) of such trap chips using reconfigurable photonic network. Complex microfabricated ion trap chips integrated with various optical components such as reflectors, lenses and optical cavities are crucial in realizing efficient interfaces for these experiments, and micromirrors can provide fast and flexible beam delivery system with individual addressing capability. I will present the progress in ion qubit manipulation on microfabricated chip traps, the integration effort with optical components, and potential application in scalable quantum computer and quantum repeater realization. This work is supported by IARPA/ARO and DARPA.

  1. Robust Quantum Information Processing with Trapped Ions in a Surface Trap

    NASA Astrophysics Data System (ADS)

    Mount, Emily; Crain, Stephen; Baek, So-Young; Gaultney, Daniel; Maunz, Peter; Kim, Jungsang

    2014-05-01

    Microfabricated surface ion traps provide a scalable platform for building a trapped ion quantum information processor. These multi-segmented traps are fabricated using existing silicon processing technology and can provide the capability to store a chain of ions and shuttle parts of the chain to various locations within the trap structure. Utilizing micro-mirrors fabricated using microelectromechanical systems (MEMS) technology, we focus and shift Raman laser beams to individual ions in the chain to perform quantum logic gates on them. Using a microfabricated surface trap made by Sandia National Laboratories we demonstrate individually addressed single qubit gates on a chain of ions driven by a repetition-rate-stabilized frequency comb. Compensating pulse sequences were utilized to mitigate the effect of the intensity fluctuations of the Raman beams. Our MEMS-based individual addressing system requires around 5 ?s to switch between different ions in the chain with crosstalk to neighboring qubits on the order of 10-5 characterized by the intensity spillover of the addressing beams. Here we present full state tomography results on un-compensated and compensated single qubit gates, single qubit gate fidelities measured by randomized benchmarking techniques, and progress towards entangling gates and their characterization.

  2. Mechanism of Hydrogen Trapping and Transport in Carbon Materials

    NASA Astrophysics Data System (ADS)

    Atsumi, H.

    Bulk hydrogen retention and hydrogen diffusion in graphite and carbon materials have been studied to estimate hydrogen recycling and tritium inventory in a fusion reactor environment. Hydrogen may permeate into a filler grain in the form of a hydrogen molecule, diffuse through crystallite boundaries and finally be trapped as hydrogen atoms at the edge surface of a crystallite. In the estimation of hydrogen transport, the activation energy of hydrogen diffusion can be determined from absorption experiments, and the activation energy of detrapping can be obtained from desorption experiments. The activation energies of hydrogen trapping are 2.6 eV in ordinary graphite and 4.4 eV for irradiated or mechanically milled graphite samples.

  3. EPR spin-trapping of protein radicals to investigate biological oxidative mechanisms

    Microsoft Academic Search

    O. Augusto; S. Muntz Vaz

    2007-01-01

    Summary.  Presently, free radicals and oxidants are considered to mediate from signaling circuits involved in physiology and pathology\\u000a to cell and tissue injury. The elucidation of these many inter-related processes requires a better understanding of cellular\\u000a oxidative mechanisms many of which are mediated by protein radicals. Here, we will discuss the potentialities of EPR spin-trapping\\u000a of protein radicals to unravel oxidative

  4. Measurements of cell wall mechanical properties using optically trapped fluorescent microspheres

    NASA Astrophysics Data System (ADS)

    Ermilov, Sergey; Qian, Feng; Murdock, David; Brownell, William E.; Anvari, Bahman

    2004-10-01

    Information on plasma membrane (PM) and cell wall mechanical properties is important for many biophysical applications, especially for those, which involve cells, undergoing significant mechanical stress (red blood cells, outer hair cells, fibrocytes, etc.). Optical tweezers is frequently used to study PM mechanics, particularly by pulling long PM tethers. One of the limitations on using optical tweezers to study cell wall mechanics is associated with transillumination technique of the trapped object position sensing, which prevents accurate mechanical testing in the proximity to the cell. In this work we use an optical tweezers in conjunction with a position-sensing system, which spectrally separates signals from the trapped fluorescent microsphere and imaging background. We have used this setup to study mechanics of the cell wall and PM separated from the underlying cytoskeleton on human embryonic kidney cells. We measured the force exerted by the cell on the trapped microsphere as a function of the cell wall displacement during the process of tether formation, and as a function of time during the process of tether growth and relaxation. Tethering force - cell wall displacement profiles have shown a behavior, implying that tether formation process starts with elastic deformation of the intact cell wall, followed by the plastic deformations and sliding of the PM over the underlying cytoskeleton, and ends with the local separation of a PM. Tethering force - cell wall displacement profiles have been used to estimate tether formation force, stiffness parameter of the cell wall and the works of tether formation, elastic and plastic deformations of the cell wall, related to the mechanical properties of a composite cell wall and cell wall - plasma membrane association strength. Temporal steady-state and relaxation tethering force profiles have been similar to the ones measured using transillumination position sensing, however average force values have been smaller in our case, due to the methodological differences. Our results demonstrate that measurements of cell wall and PM mechanical properties using optically-trapped fluorescent microspheres presents a versatile technology for studying of the cellular mechanics, especially effective in the proximity of the trapped microsphere to the cell.

  5. Theory and Simulation of Neoclassical Transport Processes, with Local Trapping

    E-print Network

    California at San Diego, University of

    Theory and Simulation of Neoclassical Transport Processes, with Local Trapping Daniel H. E. Dubin of a plasma with static electric and/or magnetic fields are of central importance in plasma theory and experiment. For exam- ple, in the theory of neoclassical transport, a magnetically confined plasma interacts

  6. Photoionization of strontium for trapped-ion quantum information processing

    E-print Network

    K. Vant; J. Chiaverini; W. Lybarger; D. J. Berkeland

    2006-07-07

    We report a demonstration of simple and effective loading of strontium ions into a linear radio frequency Paul trap using photoionization. The ionization pathway is 5s2 1S0 -- 5s5p 1P1 -- 5p2 1D2, and the 5p2 1D2 final state is auto-ionizing. Both transitions are driven using diode lasers: a grating-stabilized 922 nm diode doubled in a single pass through potassium niobate to 461 nm and a bare diode at 405 nm. Using this technique, we have reduced the background pressure during the ion loading process by a factor of 2 compared to the conventional technique of electron bombardment. Initial ion temperatures are low enough that the ions immediately form crystals. It is also possible to observe the trapping region with a CCD camera during ion creation, allowing specific ion number loading with high probability.

  7. Entanglement and Quantum Information Processing with Trapped Ions*

    NASA Astrophysics Data System (ADS)

    Chiaverini, John

    2004-05-01

    Atomic ions confined in radio frequency traps, cooled and addressed with laser pulses, constitute a scalable system for bringing about and exploring quantum entanglement and information processing. Along with relatively high entangling-gate and single-qubit-rotation fidelities, long coherence times enable the execution of some basic quantum algorithms and communication protocols. At NIST we use a multi-zone trap in which entanglement can be distributed over the zones through the spatial separation and combination of several entangled ion qubits, each of which can be separately measured. Current experiments include superdense coding, quantum teleportation, entanglement-enhanced quantum state detection, and entangled state spectroscopy. These experiments and those from other groups will be summarized. *This work was supported by ARDA/NSA and NIST, and done in collaboration with T. Schaetz, M. Barrett, D. Leibfried, J. Britton, W. Itano, J. Jost, C. Langer, R. Ozeri, T. Rosenband, and D. J. Wineland.

  8. Trap-free process and thermal limitations on large-periphery SiC MESFET for RF and microwave power

    Microsoft Academic Search

    Frédéric Villard; J.-P. Prigent; E. Morvan; C. Dua; C. Brylinski; F. Temcamani; P. Pouvil

    2003-01-01

    In this paper, we present recent results on an SiC MESFET and we describe two of the main limitation mechanisms encountered: the self-heating and the trapping effects. Results on recent MESFET devices processed by THALES Research and Technology (TRT), Colombes, France, show that the trapping effects has been solved by using epitaxial layers on a higher purity 4H-SiC semi-insulating substrate

  9. Aging process of I-cathode with magnetic ion trap

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaobing; Lei, Wei; Feng, Niangen; Havekes, Jos; Tong, Linsu; den Engelsen, Daniel

    2005-09-01

    An aging process, which applies a high frequency (HF) magnetic field on the electron gun during the aging process, is introduced to solve the unbalanced I-cathode emission slump. The effect is that the scanning electron beam and the HF magnetic field heat up the gun parts by electron bombarding and eddy current heating. In this way, the grids are effectively degassed. A part of the desorbed gases is pumped by the Ba-getter in the tube, whereas another part is ionized by electron collision. These ionized gas molecules, notably Ar +, are partially trapped in gun parts. Therefore, a lower residual gas pressure and emission slump can be achieved.

  10. Possible mechanism for enhancing the trapping and cooling of antihydrogen

    SciTech Connect

    Cesar, C. L.; Zagury, N. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, 21941-972 Rio de Janeiro, RJ (Brazil); Robicheaux, F. [Department of Physics, Auburn University, Auburn, Alabama 36849 (United States)

    2009-10-15

    We propose a usage of microwave radiation in a magnetic trap for improving the cooling and trapping of cold antihydrogen atoms which are initially produced in high magnetic moment states. Inducing transitions toward lower magnetic moments near the turning points of the atom in the trap, followed by spontaneous emission, should enhance the number of trappable atoms. We present results of simulations based on a typical experimental condition of the antihydrogen experiments at CERN. This technique should also be applicable to other trapped high magnetic moment Rydberg atoms.

  11. N-MOSFET oxide trap characterization induced by nitridation process using RTS noise analysis

    Microsoft Academic Search

    C. Leyris; F. Martinez; A. Hoffmann; M. Valenza; J. C. Vildeuil

    2007-01-01

    This paper presents oxide trap characterization of nitrided and non-nitrided gate oxide N-MOSFETs using low frequency noise (LFN) measurements. The identification of defects generated by the gate oxide growth and the nitridation process is carried out using random telegraph signal noise analysis. Significant properties of traps induced by the nitridation process are pointed out. Main trap parameters, such as their

  12. Spontaneous Firings of Carnivorous Aquatic Utricularia Traps: Temporal Patterns and Mechanical Oscillations

    PubMed Central

    Vincent, Olivier; Roditchev, Ivan; Marmottant, Philippe

    2011-01-01

    Aquatic species of Utricularia are carnivorous plants living in environments poor in nutrients. Their trapping mechanism has fascinated generations of scientists and is still debated today. It was reported recently that Utricularia traps can fire spontaneously. We show here that these spontaneous firings follow an unexpected diversity of temporal patterns, from “metronomic” traps which fire at fixed time intervals to “random” patterns, displaying more scattered firing times. Some “bursting” traps even combine both aspects, with groups of fast regular firings separated by a variable amount of time. We propose a physical model to understand these very particular behaviors, showing that a trap of Utricularia accomplishes mechanical oscillations, based on continuous pumping and sudden opening of the trap door (buckling). We isolate the key parameters governing these oscillations and discuss the effect of their fluctuations. PMID:21647417

  13. Durable repair of aged infrastructures using trapping mechanism of engineered cementitious composites

    Microsoft Academic Search

    Yun Mook Lim; Victor C. Li

    1997-01-01

    This paper introduces the concept of interface crack trapping and demonstrates experimentally the feasibility of this mechanism in a representative repaired concrete system. A microstructurally tailored Engineered Cementitious Composite (ECC) serving as the repair material was found to be most effective in trapping interface cracks such that typical failure modes in repaired systems, such as spalling or delamination, were prevented.

  14. Determination of hydroxyl radicals in an advanced oxidation process with salicylic acid trapping and liquid chromatography

    Microsoft Academic Search

    Jen-Fon Jen; Meei-Fan Leu; Thomas C Yang

    1998-01-01

    Liquid chromatography was used indirectly to detect hydroxyl radicals after a trapping reaction with salicylic acid in an advanced oxidation process. Through the quantitative determination of primary hydroxylated derivatives of salicylic acid, the concentration of hydroxyl radicals was evaluated relatively. Factors affecting the trapping reaction, such as the ratio of salicylic acid to hydrogen peroxide and trapping time, as well

  15. Investigation of Aging Mechanisms in Lean NOx Traps

    SciTech Connect

    Mark Crocker

    2010-03-31

    Lean NO{sub x} traps (LNTs) represent a promising technology for the abatement of NO{sub x} under lean conditions. Although LNTs are starting to find commercial application, the issue of catalyst durability remains problematic. LNT susceptibility to sulfur poisoning is the single most important factor determining effective catalyst lifetime. The NO{sub x} storage element of the catalyst has a greater affinity for SO{sub 3} than it does for NO{sub 2}, and the resulting sulfate is more stable than the stored nitrate. Although this sulfate can be removed from the catalyst by means of high temperature treatment under rich conditions, the required conditions give rise to deactivation mechanisms such as precious metal sintering, total surface area loss, and solid state reactions between the various oxides present. The principle objective of this project was to improve understanding of the mechanisms of lean NO{sub x} trap aging, and to understand the effect of washcoat composition on catalyst aging characteristics. The approach utilized involved detailed characterization of model catalysts prior to and after aging, in tandem with measurement of catalyst performance in NO{sub x} storage and reduction. In this manner, NO{sub x} storage and reduction characteristics were correlated with the evolution of catalyst physico-chemical properties upon aging. Rather than using poorly characterized proprietary catalysts, or simple model catalysts of the Pt/BaO/Al{sub 2}O{sub 3} type (representing the first generation of LNTs), Pt/Rh/BaO/Al{sub 2}O{sub 3} catalysts were employed which also incorporated CeO{sub 2} or CeO{sub 2}-ZrO{sub 2}, representing a model system which more accurately reflects current LNT formulations. Catalysts were prepared in which the concentration of each of the main components was systematically varied: Pt (50, 75 or 100 g/ft{sup 3}), Rh (10 or 20 g/ft{sup 3}), BaO (15, 30 or 45 g/L), and either CeO{sub 2} (0, 50 or 100 g/L) or CeO{sub 2}-ZrO{sub 2} (0, 50 or 100 g/L). A high surface area La-stabilized alumina was used to support the BaO phase. Catalysts were obtained by washcoating onto standard cordierite substrates, the total washcoat loading being set at 260 g/L. La-stabilized alumina was used as the balance. Subsequent to de-greening, the NO{sub x} storage and reduction characteristics of the catalysts were evaluated on a bench reactor, after which the catalysts were aged on a bench reactor to the equivalent of ca. 75,000 miles of road aging using a published accelerated aging protocol. The aged catalysts were then subjected to the same evaluation proecdure used for the de-greened catalysts. In addition to the use of standard physico-chemical analytical techniques for studying the fresh and aged model catalysts, use was made of advanced analytical tools for characterizing their NO{sub x} storage/reduction and sulfation/desulfation characteristics, such as Spatially resolved capillary-inlet Mass Spectrometry (SpaciMS) and in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS).

  16. Genomic mechanisms accounting for the adaptation to parasitism in nematode-trapping fungi.

    PubMed

    Meerupati, Tejashwari; Andersson, Karl-Magnus; Friman, Eva; Kumar, Dharmendra; Tunlid, Anders; Ahrén, Dag

    2013-11-01

    Orbiliomycetes is one of the earliest diverging branches of the filamentous ascomycetes. The class contains nematode-trapping fungi that form unique infection structures, called traps, to capture and kill free-living nematodes. The traps have evolved differently along several lineages and include adhesive traps (knobs, nets or branches) and constricting rings. We show, by genome sequencing of the knob-forming species Monacrosporium haptotylum and comparison with the net-forming species Arthrobotrys oligospora, that two genomic mechanisms are likely to have been important for the adaptation to parasitism in these fungi. Firstly, the expansion of protein domain families and the large number of species-specific genes indicated that gene duplication followed by functional diversification had a major role in the evolution of the nematode-trapping fungi. Gene expression indicated that many of these genes are important for pathogenicity. Secondly, gene expression of orthologs between the two fungi during infection indicated that differential regulation was an important mechanism for the evolution of parasitism in nematode-trapping fungi. Many of the highly expressed and highly upregulated M. haptotylum transcripts during the early stages of nematode infection were species-specific and encoded small secreted proteins (SSPs) that were affected by repeat-induced point mutations (RIP). An active RIP mechanism was revealed by lack of repeats, dinucleotide bias in repeats and genes, low proportion of recent gene duplicates, and reduction of recent gene family expansions. The high expression and rapid divergence of SSPs indicate a striking similarity in the infection mechanisms of nematode-trapping fungi and plant and insect pathogens from the crown groups of the filamentous ascomycetes (Pezizomycotina). The patterns of gene family expansions in the nematode-trapping fungi were more similar to plant pathogens than to insect and animal pathogens. The observation of RIP activity in the Orbiliomycetes suggested that this mechanism was present early in the evolution of the filamentous ascomycetes. PMID:24244185

  17. Testing Kibble-Zurek mechanism in ion traps

    NASA Astrophysics Data System (ADS)

    Nigmatullin, Ramil; Del Campo, Adolfo; de Chiara, Gabriele; Morigi, Giovanna; Plenio, Martin; Retzker, Alex

    2013-03-01

    A quench through a critical point of a second order phase transition results in the formation of topological defects in the system. Kibble-Zurek (KZ) theory predicts the scaling of a number of defects as a function of quench rate. This scaling depends on the critical exponents of the phase transition, and hence the study of the defect density reveals something about the nature of phase transition itself. There are a number of proposals to test KZ theory experimentally. In this talk, we discuss the possibility of studying defect formation in ion traps. A linear ion chain confined in a Paul trap undergoes a continuous phase transition to a zigzag chain when the confining potential is lowered. If the chain is in a ring trap then the zigzag chain can be in a helical configuration with a nonzero winding number. Using molecular dynamics simulations we show that the scaling of the average winding number of the resulting helical chain is consistent with KZ theory.

  18. A mechanism study of sound wave-trapping barriers.

    PubMed

    Yang, Cheng; Pan, Jie; Cheng, Li

    2013-09-01

    The performance of a sound barrier is usually degraded if a large reflecting surface is placed on the source side. A wave-trapping barrier (WTB), with its inner surface covered by wedge-shaped structures, has been proposed to confine waves within the area between the barrier and the reflecting surface, and thus improve the performance. In this paper, the deterioration in performance of a conventional sound barrier due to the reflecting surface is first explained in terms of the resonance effect of the trapped modes. At each resonance frequency, a strong and mode-controlled sound field is generated by the noise source both within and in the vicinity outside the region bounded by the sound barrier and the reflecting surface. It is found that the peak sound pressures in the barrier's shadow zone, which correspond to the minimum values in the barrier's insertion loss, are largely determined by the resonance frequencies and by the shapes and losses of the trapped modes. These peak pressures usually result in high sound intensity component impinging normal to the barrier surface near the top. The WTB can alter the sound wave diffraction at the top of the barrier if the wavelengths of the sound wave are comparable or smaller than the dimensions of the wedge. In this case, the modified barrier profile is capable of re-organizing the pressure distribution within the bounded domain and altering the acoustic properties near the top of the sound barrier. PMID:23967929

  19. Quantum mechanics of one-dimensional trapped Tonks gases

    E-print Network

    M. D. Girardeau; E. M. Wright

    2001-04-30

    Several experimental groups are currently working towards realizing quasi-one-dimensional (1D) atom waveguides and loading them with ultracold atoms. The dynamics becomes truly 1D in a regime (Tonks gas) of low temperatures and densities and large positive scattering lengths for which the transverse mode becomes frozen, in which case the many-body Schrodinger dynamics becomes exactly soluble via a Fermi-Bose mapping theorem. In this paper we review our recent work on the exact ground state and quantum dynamics of 1D Tonks gases and assess the possibility of approaching the Tonks regime using Bessel beam optical dipole traps.

  20. Evaluation of mechanically improved Conibear 220 traps to quickly kill fisher (Martes pennanti) in simulated natural environments.

    PubMed

    Proulx, G; Barrett, M W

    1993-04-01

    Mechanically improved Conibear 220 traps failed to render irreversibly unconscious in < or = 3 min fishers single-struck in the head-neck region, or double-struck in the neck and thorax regions. Although the Conibear 220 trap is often recommended as an alternative to the steel leghold trap, it is unlikely that it has the potential to humanely kill fisher. PMID:8487383

  1. Surface ion trap structures with excellent optical access for quantum information processing

    NASA Astrophysics Data System (ADS)

    Maunz, P.; Blain, M.; Benito, F.; Chou, C.; Clark, C.; Descour, M.; Ellis, R.; Haltli, R.; Heller, E.; Kemme, S.; Sterk, J.; Tabakov, B.; Tigges, C.; Stick, D.

    2013-05-01

    Microfabricated surface electrode ion traps are necessary for the advancement of trapped ion quantum information processing as it offers a scalable way for realizing complex trap structures capable of storing and controlling many ions. The most promising way of performing two-qubit quantum gates in a chain of trapped ions is to focus laser beams on individual ions of the chain to drive gates. However, in surface ion traps the close proximity of the ions to the surface and the size of the chips usually cannot accommodate the tightly focused laser beams necessary to address individual ions parallel to the chip surface. Here we present a surface electrode ion trap monolithically fabricated in standard silicon technology that implements a linear quadrupole trap on a bowtie shaped chip with a narrow section that is only 1.2 mm wide. Laser beams parallel to the surface can be focused down to a waist of 4 ?m with enough separation from the trap chip to prevent light scattering. The trap structure incorporates two Y-junctions for reordering ions and is optimized for quantum information processing. This work was supported by the Intelligence Advanced Research Projects Activity (IARPA). Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  2. Control Processes and Defense Mechanisms

    PubMed Central

    HOROWITZ, MARDI; COOPER, STEVEN; FRIDHANDLER, BRAM; PERRY, J. CHRISTOPHER; BOND, MICHAEL; VAILLANT, GEORGE

    1992-01-01

    Defense-mechanism theory and control-process theory are related psychodynamic approaches to explaining and classifying how people ward off emotional upsets. Although both theories explain defensive maneuvers in the same motivational terms, each defines categories different1y. Classic categories define defense mechanisms at a relatively macroscopic level, whereas control-process theory aims at relatively microgenetic analysis of how cognitive maneuvers—involving what is thought, how it is thought, and how it is organized—may generate defensive states. The theories are not contradictory, but they are focused on different levels of observation; it is useful to compare how these classifications are applied to specific case material. PMID:22700114

  3. Complete methods set for scalable ion trap quantum information processing

    E-print Network

    J. P. Home; D. Hanneke; J. D. Jost; J. M. Amini; D. Leibfried; D. J. Wineland

    2009-07-10

    Large-scale quantum information processors must be able to transport and maintain quantum information, and repeatedly perform logical operations. Here we demonstrate a combination of all the fundamental elements required to perform scalable quantum computing using qubits stored in the internal states of trapped atomic ions. We quantify the repeatability of a multi-qubit operation, observing no loss of performance despite qubit transport over macroscopic distances. Key to these results is the use of different pairs of beryllium ion hyperfine states for robust qubit storage, readout and gates, and simultaneous trapping of magnesium re-cooling ions along with the qubit ions.

  4. Quantum coherence and population trapping in three-photon processes

    E-print Network

    Caroline Champenois; Giovanna Morigi; Juergen Eschner

    2006-09-22

    The spectroscopic properties of a single, tightly trapped atom are studied, when the electronic levels are coupled by three laser fields in an $N$-shaped configuration of levels, whereby a $\\Lambda$-type level system is weakly coupled to a metastable state. We show that depending on the laser frequencies the response can be tuned from coherent population trapping at two-photon resonance to novel behaviour at three photon resonance, where the metastable state can get almost unit occupation in a wide range of parameters. For certain parameter regimes the system switches spontaneously between dissipative and coherent dynamics over long time scales.

  5. Study of hepatocyte plasma membrane mechanical properties using optical trapping

    NASA Astrophysics Data System (ADS)

    Vedyaykin, A. D.; Morozova, N. E.; Pobegalov, G. E.; Arseniev, A. N.; Khodorkoskii, M. A.; Sabantsev, A. V.

    2014-12-01

    In this paper we describe the use of membrane tether formation technique which is widely used to study mechanical properties of plasma membranes. This method was successfully used for the direct measurement of parameters characterizing membranes mechanical properties (static tether tension force and effective membrane viscosity) of human hepatocytes (HepG2 hepatocellular carcinoma line). These results allow using this method in future for diagnostics of the cell membrane, evaluating the influence on the mechanical parameters of various factors, including toxins and drugs.

  6. Process Waste Assessment, Mechanics Shop

    SciTech Connect

    Phillips, N.M.

    1993-05-01

    This Process Waste Assessment was conducted to evaluate hazardous wastes generated in the Mechanics Shop. The Mechanics Shop maintains and repairs motorized vehicles and equipment on the SNL/California site, to include motorized carts, backhoes, street sweepers, trash truck, portable emergency generators, trencher, portable crane, and man lifts. The major hazardous waste streams routinely generated by the Mechanics Shop are used oil, spent off filters, oily rags, and spent batteries. The used off and spent off filters make up a significant portion of the overall hazardous waste stream. Waste oil and spent batteries are sent off-site for recycling. The rags and spent on filters are not recycled. They are disposed of as hazardous waste. Mechanics Shop personnel continuously look for opportunities to minimize hazardous wastes.

  7. Experimental progress with novel surface electrode ion trap structures for quantum information processing

    NASA Astrophysics Data System (ADS)

    Clark, Craig; Blain, Matthew; Benito, Francisco; Chou, Chin-Wen; Descour, Mike; Ellis, Rob; Haltli, Ray; Heller, Edwin; Kemme, Shanalyn; Sterk, Jon; Tabakov, Boyan; Tigges, Chris; Maunz, Peter; Stick, Daniel

    2013-05-01

    Segmented surface electrode ion traps are one of the most mature platforms among candidates for scalable quantum information processing. In this poster, an overview of current results from four specific projects will be presented. Two projects involve increased light collection from trapped ion for state detection and/or remote entangling of distant ions. The first involves cavity integration into a linear surface trap, and the second, involves integration of diffractive optical elements into a linear surface trap for increased light collection. Another project involves a trap with a ring geometry which could be used to trap long chains of equally spaced ions. Finally, we report on initial testing of a trap structure with vastly improved in-plane optical access. In this structure in-plane beams can be focused to less than 8 microns while keeping a distance of at least 5 beam radii to the trap structure. Along with these projects other relevant progress from Sandia National Laboratory's ion trap group will be presented. This work was supported by Sandia's Laboratory Directed Research and Development (LDRD) and the Intelligence Advanced Research Projects Activity (IARPA). Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  8. Mechanical engineering Mechanical engineering is about solving problems, designing processes,

    E-print Network

    Waikato, University of

    Mechanical engineering Mechanical engineering is about solving problems, designing processes, and making products to improve the quality of human life and shape the economy. Mechanical engineers apply, from power stations to cars, robots and computers. The professional training mechanical engineers

  9. DESIGN OF A TRAP GREASE UPGRADER FOR BIOFUEL PROCESSING - PHASE I

    EPA Science Inventory

    This project provides capstone senior design experience to several teams of engineering undergraduates at Drexel University through the technical and economic evaluation of a trap grease to biodiesel conversion process. The project incorporates two phases: Phase I characteri...

  10. Hydrogen trapping in bearing steels: mechanisms and alloy design

    E-print Network

    Szost, Blanka Angelika

    2013-02-05

    per unit area ?E effective interfacial energy ? incubation time ? linear misfit strain Ae3 temperature separating the ferrite + the austenite and austenite phase field DC diffusion coefficient of carbon in austenite DV diffusion coefficient of vanadium... is characterised in Chapter 5. The new grade was cast and thereafter, heat treated both in a dilatometer for thermal desorption analysis and dilatometry studies, and in salt bath furnaces for mechanical testing. Microstructural observations and the measured...

  11. Magneto-mechanical resonance of a single superparamagnetic microbead trapped by a magnetic domain wall

    NASA Astrophysics Data System (ADS)

    Rapoport, Elizabeth; Beach, Geoffrey S. D.

    2012-04-01

    Magnetic domain walls in ferromagnetic tracks can be used to trap and transport superparamagnetic beads for lab-on-a-chip applications. Here it is shown that the magnetostatic binding between a domain wall and a superparamagnetic bead suspended in a host fluid leads to a distinct magneto-mechanical resonance under application of a sinusoidal driving field. The characteristic resonant frequency depends on the ratio of the magnetostatic binding force to the viscous drag on the bead. This resonance has been experimentally detected for a single trapped superparamagnetic bead using an optical detection technique.

  12. Chemically assisted mechanical refrigeration process

    DOEpatents

    Vobach, Arnold R. (6006 Allentown Dr., Spring, TX 77389)

    1987-01-01

    There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer (11) at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer (11) to form a refrigerant-solvent solution while concurrently placing the solution in heat exchange relation with a working medium to transfer energy to the working medium, said refrigerant-solvent solution exhibiting a negative deviation from Raoult's Law; reducing the pressure over the refrigerant-solvent solution in an evaporator (10) to allow the refrigerant to vaporize and substantially separate from the solvent while concurrently placing the evolving refrigerant-solvent solution in heat exchange relation with a working medium to remove energy from the working medium to thereby form a refrigerant stream and a solvent stream; and passing the solvent and refrigerant stream from the evaporator.

  13. Chemically assisted mechanical refrigeration process

    DOEpatents

    Vobach, Arnold R. (6006 Allentown Dr., Spring, TX 77379)

    1987-01-01

    There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer (11) at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer (11) to form a refrigerant-solvent solution while concurrently placing the solution in heat exchange relation with a working medium to transfer energy to the working medium, said refrigerant-solvent solution exhibiting a negative deviation from Raoult's Law; reducing the pressure over the refrigerant-solvent solution in an evaporator (10) to allow the refrigerant to vaporize and substantially separate from the solvent while concurrently placing he evolving refrigerant-solvent solution in heat exchange relation with a working medium to remove energy from the working medium to thereby form a refrigerant stream and a solvent stream; and passing the solvent and refrigerant stream from the evaporator.

  14. THE EFFECT OF SULFUR ON METHANE PARTIAL OXIDATION AND REFORMING PROCESSES FOR LEAN NOX TRAP CATALYSIS

    SciTech Connect

    Parks, II, James E [ORNL; Ponnusamy, Senthil [ORNL

    2006-01-01

    Lean NOx trap catalysis has demonstrated the ability to reduce NOx emissions from lean natural gas reciprocating engines by >90%. The technology operates in a cyclic fashion where NOx is trapped on the catalyst during lean operation and released and reduced to N2 under rich exhaust conditions; the rich cleansing operation of the cycle is referred to as "regeneration" since the catalyst is reactivated for more NOx trapping after NOx purge. Creating the rich exhaust conditions for regeneration can be accomplished by catalytic partial oxidation of methane in the exhaust system. Furthermore, catalytic reforming of partial oxidation exhaust can enable increased quantities of H2 which is an excellent reductant for lean NOx trap regeneration. It is critical to maintain clean and efficient partial oxidation and reforming processes to keep the lean NOx trap functioning properly and to reduce extra fuel consumption from the regeneration process. Although most exhaust constituents do not impede partial oxidation and reforming, some exhaust constituents may negatively affect the catalysts and result in loss of catalytic efficiency. Of particular concern are common catalyst poisons sulfur, zinc, and phosphorous. These poisons form in the exhaust through combustion of fuel and oil, and although they are present at low concentrations, they can accumulate to significant levels over the life of an engine system. In the work presented here, the effects of sulfur on the partial oxidation and reforming catalytic processes were studied to determine any durability limitations on the production of reductants for lean NOx trap catalyst regeneration.

  15. With a flick of the lid: a novel trapping mechanism in Nepenthes gracilis pitcher plants.

    PubMed

    Bauer, Ulrike; Di Giusto, Bruno; Skepper, Jeremy; Grafe, T Ulmar; Federle, Walter

    2012-01-01

    Carnivorous pitcher plants capture prey with modified leaves (pitchers), using diverse mechanisms such as 'insect aquaplaning' on the wet pitcher rim, slippery wax crystals on the inner pitcher wall, and viscoelastic retentive fluids. Here we describe a new trapping mechanism for Nepenthes gracilis which has evolved a unique, semi-slippery wax crystal surface on the underside of the pitcher lid and utilises the impact of rain drops to 'flick' insects into the trap. Depending on the experimental conditions (simulated 'rain', wet after 'rain', or dry), insects were captured mainly by the lid, the peristome, or the inner pitcher wall, respectively. The application of an anti-slip coating to the lower lid surface reduced prey capture in the field. Compared to sympatric N. rafflesiana, N. gracilis pitchers secreted more nectar under the lid and less on the peristome, thereby directing prey mainly towards the lid. The direct contribution to prey capture represents a novel function of the pitcher lid. PMID:22719998

  16. Long-term Variations of CO2 Trapped in Different Mechanisms in Deep Saline Formations: A Case Study of the Songliao Basin, China

    SciTech Connect

    Zhang, Wei; Li, Yilian; Xu, Tianfu; Cheng, Huilin; Zheng, Yan; Xiong, Peng

    2008-06-10

    The geological storage of CO{sub 2} in deep saline formations is increasing seen as a viable strategy to reduce the release of greenhouse gases to the atmosphere. There are numerous sedimentary basins in China, in which a number of suitable CO{sub 2} geologic reservoirs are potentially available. To identify the multi-phase processes, geochemical changes and mineral alteration, and CO{sub 2} trapping mechanisms after CO{sub 2} injection, reactive geochemical transport simulations using a simple 2D model were performed. Mineralogical composition and water chemistry from a deep saline formation of Songliao Basin were used. Results indicate that different storage forms of CO{sub 2} vary with time. In the CO{sub 2} injection period, a large amount of CO{sub 2} remains as a free supercritical phase (gas trapping), and the amount dissolved in the formation water (solubility trapping) gradually increases. Later, gas trapping decreases, solubility trapping increases significantly due to migration and diffusion of the CO{sub 2} plume, and the amount trapped by carbonate minerals increases gradually with time. The residual CO{sub 2} gas keeps dissolving into groundwater and precipitating carbonate minerals. For the Songliao Basin sandstone, variations in the reaction rate and abundance of chlorite, and plagioclase composition affect significantly the estimates of mineral alteration and CO{sub 2} storage in different trapping mechanisms. The effect of vertical permeability and residual gas saturation on the overall storage is smaller compared to the geochemical factors. However, they can affect the spatial distribution of the injected CO{sub 2} in the formations. The CO{sub 2} mineral trapping capacity could be in the order of ten kilogram per cubic meter medium for the Songliao Basin sandstone, and may be higher depending on the composition of primary aluminosilicate minerals especially the content of Ca, Mg, and Fe.

  17. Theory and Simulation of Neoclassical Transport Processes, with Local Trapping

    SciTech Connect

    Dubin, Daniel H. E. [Department of Physics, University of California at San Diego, La Jolla, CA USA 92093-0319 (United States)

    2009-03-30

    Neoclassical transport is studied using idealized simulations that follow guiding centers in given fields, neglecting collective effects on the plasma evolution, but including collisions at rate {nu}. For simplicity the magnetic field is assumed to be uniform; transport is due to asymmetries in applied electrostatic fields. Also, the Fokker-Planck equation describing the particle distribution is solved, and the predicted transport is found to agree with the simulations. Banana, plateau, and fluid regimes are identified and observed in the simulations. When separate trapped particle populations are created by application of an axisymmetric squeeze potential, enhanced transport regimes are observed, scaling as {radical}({nu}) when {nu}<{omega}{sub 0}<{omega}{sub b} and as 1/{nu} when {omega}{sub 0}<{nu}<{omega}{sub b} where {omega}{sub 0} and {omega}{sub b} are the rotation and axial bounce frequencies, respectively. These regimes are similar to those predicted for neoclassical transport in stellarators.

  18. Trapping mechanisms of persistent photocurrent in GaN-based MSM detectors

    Microsoft Academic Search

    Beatrice Poti; Adriana Passaseo; Mauro Lomascolo; Roberto Cingolani; Massimo De Vittorio

    2004-01-01

    The trapping mechanisms at the origin of the persistent photocurrent effects in GaN-based devices have been studied on different time scales by characterizing a low barrier metal-semiconductor-metal GaN-based photodetector in the temperature range between room temperature and 500 K. The active material of the metal-semiconductor-metal device consists of a thin film of GaN grown by metal organic chemical vapour deposition.

  19. Stochastic models of hyperfine interactions in nonequilibrium: an examination of the XYZ model with a trapping-detrapping mechanism

    NASA Astrophysics Data System (ADS)

    Zacate, Matthew O.; Evenson, William E.

    Simulations of perturbed angular correlation (PAC) spectra were carried out to investigate the effects of nonequilibrium distributions of PAC probes. The XYZ model with a trapping-detrapping mechanism was chosen to represent a system in which point defects are trapped by, detrap from, and hop around PAC probes. Calculations were based on the method of Winkler and Gerdau.

  20. Stochastic models of hyperfine interactions in nonequilibrium: an examination of the XYZ model with a trapping-detrapping mechanism

    NASA Astrophysics Data System (ADS)

    Zacate, Matthew O.; Evenson, William E.

    2007-07-01

    Simulations of perturbed angular correlation (PAC) spectra were carried out to investigate the effects of nonequilibrium distributions of PAC probes. The XYZ model with a trapping-detrapping mechanism was chosen to represent a system in which point defects are trapped by, detrap from, and hop around PAC probes. Calculations were based on the method of Winkler and Gerdau.

  1. Active movements in plants: Mechanism of trap closure by Dionaea muscipula Ellis.

    PubMed

    Markin, Vladislav S; Volkov, Alexander G; Jovanov, Emil

    2008-10-01

    The Venus flytrap (Dionaea muscipula Ellis) captures insects with one of the most rapid movements in the plant kingdom. We investigated trap closure by mechanical and electrical stimuli using the novel charge-injection method and high-speed recording. We proposed a new hydroelastic curvature mechanism, which is based on the assumption that the lobes possess curvature elasticity and are composed of outer and inner hydraulic layers with different hydrostatic pressure. The open state of the trap contains high elastic energy accumulated due to the hydrostatic pressure difference between the hydraulic layers of the lobe. Stimuli open pores connecting the two layers, water rushes from one hydraulic layer to another, and the trap relaxes to the equilibrium configuration corresponding to the closed state. In this paper we derived equations describing this system based on elasticity Hamiltonian and found closing kinetics. The novel charge-injection stimulation method gives insight into mechanisms of the different steps of signal transduction and response in the plant kingdom. PMID:19513230

  2. Regimes of particle trapping in inductively coupled plasma processing Helen H. Hwanga)

    E-print Network

    Kushner, Mark

    Regimes of particle trapping in inductively coupled plasma processing reactors Helen H. Hwanga Contamination of wafers by particles in plasma processing reactors is a continuing problem affecting yields in a high plasma density inductively coupled plasma ICP reactor. When operating with an unbiased substrate

  3. MECHANISMS OF DRY SO2 CONTROL PROCESSES

    EPA Science Inventory

    The report discusses physical and chemical processes and reaction mechanisms for lime spray drying and dry injection of sodium compounds in dry flue gas desulfurization (FGD) processes. It includes: chemical reactions, physical changes, proposed reaction mechanisms and mathematic...

  4. Grover-like search via a Frenkel-exciton trapping mechanism

    SciTech Connect

    Thilagam, A. [Applied Centre for Structural and Synchrotron Studies, University of South Australia, Adelaide 5095 (Australia)

    2010-03-15

    We propose the physical implementation of a Grover-like search problem by means of Frenkel exciton trapping at a shallow isotopic impurity against a background of competing mechanisms. The search, culminating at the impurity molecule, designated the 'winner' site, is marked by its enhanced interaction with acoustic phonons at low temperatures. The quantum search proceeds with the assistance of an oracle-like exciton-phonon interaction that addresses only the impurity site via the Dyson propagator within the Green's function formalism. The optimum parameters of a graph lattice with long-range intersite interactions required to trap the exciton in the fastest time are determined, and estimates of error rates for the naphthalene-doped organic system are evaluated. We extend the analysis of the quantum search to a fluctuating long-range interacting cycle (LRIC) graph-lattice system.

  5. Exhaustive and Heuristic Retrieval Processes in Person Cognition: Further Tests of the TRAP Model

    E-print Network

    Patel, Aniruddh D.

    Exhaustive and Heuristic Retrieval Processes in Person Cognition: Further Tests of the TRAP Model, the advantage in recall of expectancy-incongruent over congruent information in person cognition (Hastie & Kumar as a result of the difficulties of integrating incongruent with congruent information in a unified person

  6. Threshold voltage instability mechanisms of nitride based charge trap flash memory--a review.

    PubMed

    Lee, Meng Chuan; Wong, Hirt Yong

    2014-07-01

    Technological scaling of charge trap device has become significantly more challenging due to two major physical limits revealed by International Technology Roadmap for Semiconductors (ITRS) 2011, i.e., (1) neighboring bit interference due to consistent shrinking in design floor space; (2) balancing act of ensuring sufficient number of electrons in shrinking storage layer to maintain stable threshold voltage (V(t)) against various V(t) instability mechanisms. Nitride based charge trap flash (CTF) is one of the better candidates to replace floating gate (FG) flash as the mainstream flash memory technology due to its inherent immunity to point defects and better device scalability. However, post cycled V(t) instability in the form of V(t) distribution shift and broadening of programmed/erased cells is still genuine reliability concerns for nitride based CTF devices. This is because the shift and broadening of V(t) distribution could degrade the operating window and thus caused premature failures of the devices. V(t) instability of nitride based CTF memory inevitably introduces statistical fluctuations in V(t) distribution of nitride based CTF which is detrimental to its long-term data retention performance. The scope of this review paper focuses on critical reliability challenges of future development of nitride based CTF development with emphasis on cell level V(t) instability mechanisms. Our review on recent findings of V(t) instability mechanisms are useful references for future development of nitride based CTF devices. PMID:24757947

  7. Pore-Scale Research of Trapping Mechanisms and Caprock Sealing Efficiency Relevant to CO2 Sequestration: Experimental Capability Development at EMSL\\/PNNL

    Microsoft Academic Search

    T. W. Wietsma; C. Zhang; M. Oostrom; J. W. Grate

    2010-01-01

    Capture and sequestration of anthropogenic CO2 in depleted oil and gas reservoirs, unminable coal seams and deep saline aquifer are being intensively studied as a promising strategy to mitigate CO2 emission into the atmosphere. Two critical research areas are trapping mechanisms and caprock sealing efficiency, which are controlled by interfacial processes at the fluid-fluid and fluid-rock interfaces. Fundamental understanding of

  8. The mechanism of radical-trapping antioxidant activity of plant-derived thiosulfinates.

    PubMed

    Lynett, Philip T; Butts, Krista; Vaidya, Vipraja; Garrett, Graham E; Pratt, Derek A

    2011-05-01

    It has long been recognized that garlic and petiveria, two plants of the Allium genus--which also includes onions, leeks and shallots--possess great medicinal value. In recent times, the biological activities of extracts of these plants have been ascribed to the antioxidant properties of the thiosulfinate secondary metabolites allicin and S-benzyl phenylmethanethiosulfinate (BPT), respectively. Herein we describe our efforts to probe the mechanism of the radical-trapping antioxidant activity of these compounds, as well as S-propyl propanethiosulfinate (PPT), a saturated analog representative of the thiosulfinates that predominate in non-medicinal alliums. Our experimental results, which include thiosulfinate-inhibited autoxidations of the polyunsaturated fatty acid (ester) methyl linoleate, investigations of their decomposition kinetics, and radical clock experiments aimed at obtaining some quantitative insights into their reactions with peroxyl radicals, indicate that the radical-trapping activity of thiosulfinates is paralleled by their propensity to undergo Cope elimination to yield a sulfenic acid. Since sulfenic acids are transient species, we complement our experimental studies with the results of theoretical calculations aimed at understanding the radical-trapping behaviour of the sulfenic acids derived from allicin, BPT and PPT, and contrasting the predicted thermodynamics and kinetics of their reactions with those of the parent thiosulfinates. The calculations reveal that sulfenic acids have among the weakest O-H bonds known (ca. 70 kcal mol(-1)), and that their reactions with peroxyl radicals take place by a near diffusion-controlled proton-coupled electron transfer mechanism. As such, it is proposed that the abundance of a thiosulfinate in a given plant species, and the ease with which it undergoes Cope elimination to form a sulfenic acid, accounts for the differences in antioxidant activity, and perhaps medicinal value, of extracts of these plants. Interestingly, while the Cope elimination of 2-propenesulfenic acid from allicin is essentially irreversible, the analogous reaction of BPT is readily reversible. Thus, in the absence of chain-carrying peroxyl radicals (or other appropriately reactive trapping agent), BPT is reformed. PMID:21445384

  9. Mass measurements near the $r$-process path using the Canadian Penning Trap mass spectrometer

    E-print Network

    J. Van Schelt; D. Lascar; G. Savard; J. A. Clark; S. Caldwell; A. Chaudhuri; J. Fallis; J. P. Greene; A. F. Levand; G. Li; K. S. Sharma; M. G. Sternberg; T. Sun; B. J. Zabransky

    2012-04-09

    The masses of 40 neutron-rich nuclides from Z = 51 to 64 were measured at an average precision of $\\delta m/m= 10^{-7}$ using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. The measurements, of fission fragments from a $^{252}$Cf spontaneous fission source in a helium gas catcher, approach the predicted path of the astrophysical $r$ process. Where overlap exists, this data set is largely consistent with previous measurements from Penning traps, storage rings, and reaction energetics, but large systematic deviations are apparent in $\\beta$-endpoint measurements. Differences in mass excess from the 2003 Atomic Mass Evaluation of up to 400 keV are seen, as well as systematic disagreement with various mass models.

  10. Mechanics,Mechanisms and Modeling of the Chemical Mechanical Polishing Process

    E-print Network

    Noh, Kyungyoon

    The Chemical Mechanical polishing (CMP) process is now widely employed in the Integrated Circuit Fabrication. However, due to the complexity of process parameters on the material removal rate (MRR), mechanism of material ...

  11. Study of the aerodynamic trap for containerless laser materials processing in microgravity

    NASA Astrophysics Data System (ADS)

    Paradis, Paul-François; Babin, François; Gagné, Jean-Marie

    1996-01-01

    In the context of containerless laser processing of glasses in microgravity, a systematic study of the aerodynamic trap (ADT) has been done on the ground at both ambient and very high temperatures (?2000 K). This work yielded a better understanding of the ADT and helped in improving its design. Experiments indicate that restoring force and sample stability depend upon the diffuser's interior angle, flow rate, and ratio of sample to diffuser's throat diameters. It was found that the trap's potential energy curve versus position had a barrier height that increased with flow rate but decreased with increasing angle of the diffuser. Small angle diffusers show a greater spatial extent of the potential well, higher sphere-to-wall distances, and greater sample stability than larger angle diffusers. Low flow rates give quieter environments (smaller oscillations and perturbations due to the gas flow) than higher flow rates even though they are sufficient to trap the sample and damp external perturbations. Heat loss by forced air cooling is thus reduced, enabling the processing of larger samples for a given laser power. The research suggests that for dielectric samples of ?3 mm diameter, at ambient, as well as at high temperature, where stability is a necessity, the ADT should be a small angle diffuser (30°-60°) operated at low flow rate (<4.4 l/min with a 1 mm throat diameter). These conditions allow stable positioning for ambient as well as for high-temperature containerless materials sciences experiments on the ground and in microgravity. The sample should stay positioned and contactless even during large acceleration variations (2 g-?g) with minimum perturbation allowing its use in a KC-135 aircraft environment. Also, a spherical sample whose size varies through evaporation can be continuously trapped in a unique conical diffuser as long as its diameter is greater than that of the throat.

  12. Quantum-mechanical Brayton engine working with a particle in a one-dimensional harmonic trap

    NASA Astrophysics Data System (ADS)

    Wang, H.

    2013-05-01

    Based on the quantum version of thermodynamic processes, a quantum-mechanical Brayton engine model has been established. Expressions for the power output and efficiency of the engine are derived. Some fundamental optimal relations and general performance characteristic curves of the cycle are obtained. Furthermore, we note that it is possible to resist the reduction in efficiency, caused by compression of the adiabatic process, by decreasing the amount of energy levels of the quantum system. The results obtained here will provide theoretical guidance for the design of some new quantum-mechanical engines.

  13. An extracellular matrix-based mechanism of rapid neutrophil extracellular trap formation in response to C. albicans1

    PubMed Central

    Byrd, Angel S.; O’Brien, Xian M.; Johnson, Courtney M.; Lavigne, Liz M.; Reichner, Jonathan S.

    2013-01-01

    The armament of neutrophil-mediated host defense against pathogens includes the extrusion of a lattice of DNA and microbicidal enzymes known as Neutrophil Extracellular Traps (NETs). The receptor:ligand interactions and intracellular signaling mechanisms responsible for elaborating NETs were determined for the response to Candida albicans. Since the host response of extravasated neutrophils to mycotic infections within tissues necessitates contact with ECM, this study also identified a novel and significant regulatory role for the ubiquitous matrix component fibronectin (Fn) in NET release. We report that recognition of purified fungal pathogen-associated molecular pattern ?-glucan by human neutrophils causes rapid (? 30 mins) homotypic aggregation and NET release by a mechanism that requires Fn. Alone, immobilized ?-glucan induces reactive oxygen species (ROS) production but not NET release, whereas in the context of Fn, ROS production is suppressed and NETs are extruded. NET release to Fn + ?-glucan is robust, accounting for 17.2 ± 3.4% of total DNA in the cell population. Release is dependent on ?-glucan recognition by CR3 (CD11b/CD18), but not Dectin-1, or ROS. The process of NET release included filling of intracellular vesicles with nuclear material that was eventually extruded. We identify a role for ERK in homotypic aggregation and NET release. NET formation to C. albicans hyphae was also found to depend on ?-glucan recognition by CR3, require Fn and ERK but not ROS, and result in hyphal destruction. We report a new regulatory mechanism of NETosis in which the extracellular matrix is a key component of the rapid anti-fungal response. PMID:23509360

  14. An extracellular matrix-based mechanism of rapid neutrophil extracellular trap formation in response to Candida albicans.

    PubMed

    Byrd, Angel S; O'Brien, Xian M; Johnson, Courtney M; Lavigne, Liz M; Reichner, Jonathan S

    2013-04-15

    The armament of neutrophil-mediated host defense against pathogens includes the extrusion of a lattice of DNA and microbicidal enzymes known as neutrophil extracellular traps (NETs). The receptor/ligand interactions and intracellular signaling mechanisms responsible for elaborating NETs were determined for the response to Candida albicans. Because the host response of extravasated neutrophils to mycotic infections within tissues necessitates contact with extracellular matrix, this study also identified a novel and significant regulatory role for the ubiquitous matrix component fibronectin (Fn) in NET release. We report that recognition of purified fungal pathogen-associated molecular pattern ?-glucan by human neutrophils causes rapid (? 30 min) homotypic aggregation and NET release by a mechanism that requires Fn. Alone, immobilized ?-glucan induces reactive oxygen species (ROS) production but not NET release, whereas in the context of Fn, ROS production is suppressed and NETs are extruded. NET release to Fn with ?-glucan is robust, accounting for 17.2 ± 3.4% of total DNA in the cell population. Release is dependent on ?-glucan recognition by complement receptor 3 (CD11b/CD18), but not Dectin-1, or ROS. The process of NET release included filling of intracellular vesicles with nuclear material that was eventually extruded. We identify a role for ERK in homotypic aggregation and NET release. NET formation to C. albicans hyphae was also found to depend on ?-glucan recognition by complement receptor 3, require Fn and ERK but not ROS, and result in hyphal destruction. We report a new regulatory mechanism of NETosis in which the extracellular matrix is a key component of the rapid antifungal response. PMID:23509360

  15. Halogenated organic gas-induced lung toxicity by free radical mechanisms. An EPR/Spin trapping study

    SciTech Connect

    Arroyo, C.M.

    1993-05-13

    Edemagenic gases have been studied to determine physicochemical properties and basic mechanism(s) of response. The reaction of phosgene with nitrone spin traps was investigated using EPR/Spin Trapping techniques. A carbamoyl monochloride intermediate was obtained. Isotopic substitution of (13)C-phosgene was employed to verify the hyperfine coupling constant assignments. Furthermore, applying EPR/Spin Trapping techniques several intermediate species were identified in the reaction of perfluoroisobutylene (PFIB) with nitrone and nitroso spin trap agents: a carbon dioxide radical ion (CO2), a carbamoyl monofluoride intermediate (+COF), and vinyl carbanions of PFIB. Nitrone compounds formed 1,3-cycloaddition products with PFIB under anaerobic and aprotic conditions. Nitroso compounds reacted with carbanions derived from PFIB, which raises the possibility that electron transfer reactions of this type might account for the observed nitroxides. From these studies it appears that the toxicity of PFIB may be correlated with its susceptibility to nucleophilic attack. In the case of phosgene, a propagated electron transfer catalysis may be partially responsible for the pathogenesis of acute lung injury from inhalation of phosgene.

  16. Pore-Scale Research of Trapping Mechanisms and Caprock Sealing Efficiency Relevant to CO2 Sequestration: Experimental Capability Development at EMSL/PNNL

    NASA Astrophysics Data System (ADS)

    Wietsma, T. W.; Zhang, C.; Oostrom, M.; Grate, J. W.

    2010-12-01

    Capture and sequestration of anthropogenic CO2 in depleted oil and gas reservoirs, unminable coal seams and deep saline aquifer are being intensively studied as a promising strategy to mitigate CO2 emission into the atmosphere. Two critical research areas are trapping mechanisms and caprock sealing efficiency, which are controlled by interfacial processes at the fluid-fluid and fluid-rock interfaces. Fundamental understanding of capillary/viscous effects and host rock heterogeneity on trapping mechanisms and sealing efficiency can be gained through micromodel pore-scale displacement experiments. Experimental capabilities are being developed at the Environmental Molecular Sciences Lab (EMSL), Pacific Northwest National Laboratory (PNNL) to study coupled flow and reactive transport processes in complex systems at the pore-scale at relevant storage pressures and temperatures. This presentation highlights our strategies for design and construction of a unique high-pressure system for micromodel experimentation and a capability for visualizing dynamic interfacial processes using a solvatochromic dye under supercritical conditions. Preliminary results on displacement of brine by supercritical CO2 will be presented.

  17. IL-17A promotes macrophage effector mechanisms against Trypanosoma cruzi by trapping parasites in the endolysosomal compartment.

    PubMed

    Erdmann, Hanna; Roßnagel, Caroline; Böhme, Julia; Iwakura, Yoichiro; Jacobs, Thomas; Schaible, Ulrich E; Hölscher, Christoph

    2013-06-01

    The contribution of the IL-23-IL-17A pathway to resistance against extracellular bacterial infections is well established, whereas its role in immunity to intracellular pathogens is much less clear. To analyze the contribution of the IL-23-IL-17A-axis to resistance against Trypanosoma cruzi infection, we infected IL-23p19(-/-) mice and IL-17A(-/-) mice with T. cruzi. Both mouse strains were susceptible to T. cruzi infection despite strong Th1 immune responses. In vitro experiments revealed that IL-17A, but not IL-23, directly stimulates macrophages to internalize T. cruzi parasites by phagocytosis, which is in contrast to the active invasion process normally used by T. cruzi. In contrast to the active entry of parasites into macrophages, the IL-17A-driven phagocytosis prolonged residency of parasites in the endosomal/lysosomal compartment of the macrophage, which subsequently led to eradication of parasites. This IL-17A-dependent mechanism represents a novel function of IL-17A trapping pathogens in endosomal/lysosomal compartments and enhancing exposure time to antimicrobial effectors of the macrophage. PMID:23182712

  18. Effect of de-trapping on carrier transport process in semi-insulating CdZnTe

    NASA Astrophysics Data System (ADS)

    Guo, Rong-Rong; Jie, Wan-Qi; Zha, Gang-Qiang; Xu, Ya-Dong; Feng, Tao; Wang, Tao; Du, Zhuo-Tong

    2015-06-01

    The effect of de-trapping on the carrier transport process in the CdZnTe detector is studied by laser beam-induced transient current (LBIC) measurement. Trapping time, de-trapping time, and mobility for electrons are determined directly from transient waveforms under various bias voltages. The results suggest that an electric field strengthens the capture and emission effects in trap center, which is associated with field-assisted capture and the Poole–Frenkel effect, respectively. The electron mobility is calculated to be 950 cm2/V·s and the corresponding electron mobility-lifetime product is found to be 1.32×10?3 cm2/V by a modified Hecht equation with considering the surface recombination effect. It is concluded that the trapping time and de-trapping time obtained from LBIC measurement provide direct information concerning the transport process. Project supported by the National Instrumentation Program, China (Grant No. 2011YQ040082), the National Natural Science Foundation of China (Grant Nos. 61274081, 51372205, and 51202197), the National 973 Project of China (Grant No. 2011CB610400), the China Postdoctoral Science Foundation (Grant No. 2014M550509), and the 111 Project of China (Grant No. B08040).

  19. A Process Algebra Approach to Quantum Mechanics

    E-print Network

    William H. Sulis

    2014-09-07

    The process approach to NRQM offers a fourth framework for the quantization of physical systems. Unlike the standard approaches (Schrodinger-Heisenberg, Feynman, Wigner-Gronewald-Moyal), the process approach is not merely equivalent to NRQM and is not merely a re-interpretation. The process approach provides a dynamical completion of NRQM. Standard NRQM arises as a asymptotic quotient by means of a set-valued process covering map, which links the process algebra to the usual space of wave functions and operators on Hilbert space. The process approach offers an emergentist, discrete, finite, quasi-non-local and quasi-non-contextual realist interpretation which appears to resolve many of the paradoxes and is free of divergences. Nevertheless, it retains the computational power of NRQM and possesses an emergent probability structure which agrees with NRQM in the asymptotic quotient. The paper describes the process algebra, the process covering map for single systems and the configuration process covering map for multiple systems. It demonstrates the link to NRQM through a toy model. Applications of the process algebra to various quantum mechanical situations - superpositions, two-slit experiments, entanglement, Schrodinger's cat - are presented along with an approach to the paradoxes and the issue of classicality.

  20. Large-scale photonic neural networks with biology-like processing elements: the role of electron-trapping materials

    NASA Astrophysics Data System (ADS)

    Farhat, Nabil H.; Wen, Zhimin

    1995-08-01

    Neural networks employing pulsating biology-oriented integrate-and-fire (IF) model neurons, that can exhibit synchronicity (phase-locking), bifurcation, and chaos, have features that make them potentially useful for learning and recognition of spatio-temporal patterns, generation of complex motor control, emulating higher-level cortical functions like feature binding, separation of object from background, cognition and other higher-level functions; all of which are beyond the ready reach of nonpulsating sigmoidal neuron networks. The spiking nature of biology-oriented neural networks makes their study in digital hardware impractical. Prange and Klar convincingly argued that the best way of realizing such networks is through analog CMOS technology rather than digital hardware. They showed, however, that the number of neurons one can accommodate on a VLSI chip limited to a hundred or so, even when submicron CMOS technology is used, because of the relatively large size of the neuron/dendrite cell. One way of reducing the size of neuron/dendrite cell is to reduce the structural complexity of the cell by realizing some of the processes needed in the cell's operation externally to the chip and by coupling these processes to the cell optically. Two such processes are the relaxation mechanism of the IF neuron and dendritic-tree processing. We have shown, by examining the blue light impulse response of electron trapping materials (ETMs) used under simultaneous infrared and blue light bias, that these materials offer features that can be used in realizing both the optical relaxation and synapto-dendritic response mechanisms. Experimental results demonstrating the potential of this approach in realizing dense arrays of biology-oriented neuron/dendrite cells will be presented, focusing on the concept and design of ETM-based image intensifier as new enabling technology.

  1. Processing of strong flux trapping high T(subc) oxide superconductors: Center director's discretionary fund

    NASA Technical Reports Server (NTRS)

    Wu, M. K.; Higgins, C. A.; Leong, P. T.; Chou, H.; Loo, B. H.; Curreri, P. A.; Peters, P. N.; Sisk, R. C.; Huang, C. Y.; Shapira, Y.

    1989-01-01

    Magnetic suspension effect was first observed in samples of YBa2Cu3O7/AgO(Y-123/AgO) composites. Magnetization measurements of these samples show a much larger hysteresis which corresponds to a large critical current density. In addition to the Y-123AgO composites, recently similar suspension effects in other RE-123/AgO, where RE stands for rare-Earth elements, were also observed. Some samples exhibit even stronger flux pinning than that of the Y-123/AgO sample. An interesting observation was that in order to form the composite which exhibits strong flux trapping effect the sintering temperature depends on the particular RE-123 compound used. The paper presents the detailed processing conditions for the formation of these RE-123/AgO composites, as well as the magnetization and critical field data.

  2. A Signal Processing Model of Quantum Mechanics

    E-print Network

    Chris Thron; Johnny Watts

    2012-05-08

    This paper develops a deterministic model of quantum mechanics as an accumulation-and-threshold process. The model arises from an analogy with signal processing in wireless communications. Complex wavefunctions are interpreted as expressing the amplitude and phase information of a modulated carrier wave. Particle transmission events are modeled as the outcome of a process of signal accumulation that occurs in an extra (non-spacetime) dimension. Besides giving a natural interpretation of the wavefunction and the Born rule, the model accommodates the collapse of the wave packet and other quantum paradoxes such as EPR and the Ahanorov-Bohm effect. The model also gives a new perspective on the 'relational' nature of quantum mechanics: that is, whether the wave function of a physical system is "real" or simply reflects the observer's partial knowledge of the system. We simulate the model for a 2-slit experiment, and indicate possible deviations of the model's predictions from conventional quantum mechanics. We also indicate how the theory may be extended to a field theory.

  3. Measurement and Fundamental Processes in Quantum Mechanics

    NASA Astrophysics Data System (ADS)

    Jaeger, Gregg

    2015-07-01

    In the standard mathematical formulation of quantum mechanics, measurement is an additional, exceptional fundamental process rather than an often complex, but ordinary process which happens also to serve a particular epistemic function: during a measurement of one of its properties which is not already determined by a preceding measurement, a measured system, even if closed, is taken to change its state discontinuously rather than continuously as is usual. Many, including Bell, have been concerned about the fundamental role thus given to measurement in the foundation of the theory. Others, including the early Bohr and Schwinger, have suggested that quantum mechanics naturally incorporates the unavoidable uncontrollable disturbance of physical state that accompanies any local measurement without the need for an exceptional fundamental process or a special measurement theory. Disturbance is unanalyzable for Bohr, but for Schwinger it is due to physical interactions' being borne by fundamental particles having discrete properties and behavior which is beyond physical control. Here, Schwinger's approach is distinguished from more well known treatments of measurement, with the conclusion that, unlike most, it does not suffer under Bell's critique of quantum measurement. Finally, Schwinger's critique of measurement theory is explicated as a call for a deeper investigation of measurement processes that requires the use of a theory of quantum fields.

  4. Alternative Interpretation of Low-Energy Nuclear Reaction Processes with Deuterated Metals Based on The Bose-Einstein Condensation Mechanism

    Microsoft Academic Search

    Yeong E. Kim; Thomas O. Passell

    Recently, a generalization of the Bose-Einstein condensation (BEC) mechanism has been made to a ground-state mixture of two different species of positively charged bosons in harmonic traps. The theory has been used to describe (D + Li) reactions in the low energy nuclear reaction (LENR) processes in condensed matter and predicts that the (D + Li) reaction rates can be

  5. Alternative Interpretation of Low-Energy Nuclear Reaction Processes with Deuterated Metals Based on the Bose-Einstein Condensation Mechanism

    Microsoft Academic Search

    Yeong E. Kim; Thomas O. Passell

    2006-01-01

    Recently, a generalization of the Bose-Einstein condensation (BEC) mechanism has been made to a ground-state mixture of two different species of positively charged bosons in harmonic traps. The theory has been used to describe (D + Li) reactions in the low energy nuclear reaction (LENR) processes in condensed matter and predicts that the (D + Li) reaction rates can be

  6. 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. [Koc University, Rumelifeneriyolu, Sariyer, Istanbul TR-34450 (Turkey); LASIM, Universite de Lyon and CNRS UMR 5579, 43 Bd du 11 Novembre 1918, FR-69622 Villeurbanne Cedex (France)

    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.

  7. Density estimation of Bemisia tabaci (Hemiptera: Aleyrodidae) in a greenhouse using sticky traps in conjunction with an image processing system

    Microsoft Academic Search

    Mu Qiao; Jaehong Lim; Chang Woo Ji; Bu-Keun Chung; Hwang-Yong Kim; Ki-Baik Uhm; Cheol Soo Myung; Jongman Cho; Tae-Soo Chon

    2008-01-01

    Accurate forecasting of pest density is essential for effective pest management. In this study, a simple image processing system that automatically estimated the density of whiteflies on sticky traps was developed. The estimated densities of samples in a laboratory and a greenhouse were in accordance with the actual values. The detection system was especially efficient when the whitefly densities were

  8. MECHANISMS UNDERLYING THE EFFECTIVENESS OF FOOD PROCESSING IPM PROGRAMS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Comprehensive integrated pest management programs designed for commercial food processing facilities typically rely on sanitation, application of residual insecticides, and pheromone-baited traps for monitoring. The purpose of these studies was to characterize changes in insect behavior and age st...

  9. System Enhancements for Mechanical Inspection Processes

    NASA Technical Reports Server (NTRS)

    Hawkins, Myers IV

    2011-01-01

    Quality inspection of parts is a major component to any project that requires hardware implementation. Keeping track of all of the inspection jobs is essential to having a smooth running process. By using HTML, the programming language ColdFusion, and the MySQL database, I created a web-based job management system for the 170 Mechanical Inspection Group that will replace the Microsoft Access based management system. This will improve the ways inspectors and the people awaiting inspection view and keep track of hardware as it is in the inspection process. In the end, the management system should be able to insert jobs into a queue, place jobs in and out of a bonded state, pre-release bonded jobs, and close out inspection jobs.

  10. Isolated, slowly evolving, and dynamical trapping horizons: Geometry and mechanics from surface deformations

    SciTech Connect

    Booth, Ivan; Fairhurst, Stephen [Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, A1C 5S7 (Canada); Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, 53201 (United States)

    2007-04-15

    We study the geometry and dynamics of both isolated and dynamical trapping horizons by considering the allowed variations of their foliating two-surfaces. This provides a common framework that may be used to consider both their possible evolutions and their deformations as well as derive the well-known flux laws. Using this framework, we unify much of what is already known about these objects as well as derive some new results. In particular we characterize and study the 'almost isolated' trapping horizons known as slowly evolving horizons. It is for these horizons that a dynamical first law holds and this is analogous and closely related to the Hawking-Hartle formula for event horizons.

  11. Opto-Mechanical and Electronic Design of a Tunnel-Trap Si Radiometer

    Microsoft Academic Search

    George P. Eppeldauer

    2000-01-01

    A transmission-type light-trap silicon radiometer has been developed to hold the NIST spectral power and irradiance responsivity scales between 406 nm and 920 nm. The device is built from replace- able input apertures and tightly packed different-size silicon photodiodes. The photodiodes are positioned in a triangular shape tunnel such that beam clipping is entirely eliminated within an 8 field-of- view

  12. Progress Towards Trapped-Ion Quantum Information Processing at McMaster University.

    NASA Astrophysics Data System (ADS)

    King, Brian

    2005-05-01

    We are constructing a trapped-ion quantum information processor to explore quantum computing technology and applications and general quantum state engineering. In particular, we will trap ^24Mg^+ and ^25Mg^+ ions in a linear RF (Paul) trap geometry. We will use the ground-state hyperfine levels of the ^25Mg^+ ions as internal-state qubits and the ions' shared motional degree of freedom as a ``quantum data bus.'' We discuss progress in constructing the apparatus, including an all-solid-state source of 280-nm UV laser light.

  13. Constraints on Transport and Emplacement Mechanisms of Labile Fractions in Lunar Cold Traps

    NASA Technical Reports Server (NTRS)

    Rickman, D.; Gertsch, L.

    2014-01-01

    Sustaining the scientific exploration of the Solar System will require a significant proportion of the necessary fuels and propellants, as well as other bulk commodities, to be produced from local raw materials [1]. The viability of mineral production depends on the ability to locate and characterize mineable deposits of the necessary feedstocks. This requires, among other things, a workable understanding of the mechanisms by which such deposits form, which is the subject of Economic Geology. Multiple deposition scenarios are possible for labile materials on the Moon. This paper suggests labile fractions moved diffusely through space; deposits may grow richer with depth until low porosity rock; lateral transport is likely to have occurred with the regolith, at least for short distances; crystalline ice may not exist; the constituent phases could be extremely complex. At present we can constrain the sources only mildly; once on the Moon, the transport mechanisms inherently mix and therefore obscure the origins. However, the importance of expanding our understanding of ore-forming processes on the Moon behooves us to make the attempt. Thus begins a time of new inquiry for Economic Geology.

  14. Temperature dependence of the trapped field and mechanical properties of neutron irradiated and reinforced YBa2Cu3O7-? bulk superconductors

    Microsoft Academic Search

    Raquel Gonzalez-Arrabal; Michael Eisterer; Harald W. Weber; Günter Fuchs; Peter Verges; Gernot Krabbes; Masaru Tomita; Masato Murakami; Doris Litzkendorf; Tobias Habisreuther; Wolfgang Gawalek

    2003-01-01

    We report on the temperature dependence of the trapped field in neutron irradiated YBa2Cu3O7-? bulk melt-textured materials. The field trapping capability of these materials at low temperatures is limited by their mechanical properties. We observe that samples without reinforcement usually break during activation at temperatures of around 50 K. Two reinforcement techniques were tested. Resin impregnation is found to be

  15. Density of Trap States and Auger-mediated Electron Trapping in CdTe Quantum-Dot Solids.

    PubMed

    Boehme, Simon C; Azpiroz, Jon Mikel; Aulin, Yaroslav V; Grozema, Ferdinand C; Vanmaekelbergh, Daniël; Siebbeles, Laurens D A; Infante, Ivan; Houtepen, Arjan J

    2015-05-13

    Charge trapping is an ubiquitous process in colloidal quantum-dot solids and a major limitation to the efficiency of quantum dot based devices such as solar cells, LEDs, and thermoelectrics. Although empirical approaches led to a reduction of trapping and thereby efficiency enhancements, the exact chemical nature of the trapping mechanism remains largely unidentified. In this study, we determine the density of trap states in CdTe quantum-dot solids both experimentally, using a combination of electrochemical control of the Fermi level with ultrafast transient absorption and time-resolved photoluminescence spectroscopy, and theoretically, via density functional theory calculations. We find a high density of very efficient electron traps centered ?0.42 eV above the valence band. Electrochemical filling of these traps increases the electron lifetime and the photoluminescence quantum yield by more than an order of magnitude. The trapping rate constant for holes is an order of magnitude lower that for electrons. These observations can be explained by Auger-mediated electron trapping. From density functional theory calculations we infer that the traps are formed by dicoordinated Te atoms at the quantum dot surface. The combination of our unique experimental determination of the density of trap states with the theoretical modeling of the quantum dot surface allows us to identify the trapping mechanism and chemical reaction at play during charge trapping in these quantum dots. PMID:25853555

  16. Mechanisms of charge trapping at a dielectric surface: Resonance stabilization and dissociative attachment

    SciTech Connect

    Sanche, L.; Deschenes, M.

    1988-10-31

    A solid Kr film partially covered with O/sub 2/ molecules is charged by a 0- to 10-eV electron beam. The electron energy dependence of the trapping cross section indicates that surface charging in the 0--2-eV range is due to stabilization via the /sup 2/Pi/sub g/ O/sub 2//sup -/ resonance, whereas in the 4--10-eV region, it is due to O/sup -/(/sup 2/P) formed by dissociation of the intermediate /sup 2/Pi/sub u/ state of O/sub 2//sup -/.

  17. Influence of the inductor shape, and the magnetization processes on a trapped magnetic flux in a superconducting bulk

    NASA Astrophysics Data System (ADS)

    Gony, B.; Linares, R.; Lin, Q.; Berger, K.; Douine, B.; Leveque, J.

    2014-08-01

    In this paper, we study the form of the inductor for producing a magnetic field in a superconductor bulk by using a method of PFM (Pulsed Field Magnetization). We tested two inductors: vortex coil and system of three coils, where we found the best results with the system of three coils. After that, we presented two processes for trapping a magnetic field in the bulk: direct magnetization and successive magnetization where we found similar results.

  18. Measurements of cell wall mechanical properties using optically trapped fluorescent microspheres

    Microsoft Academic Search

    Sergey Ermilov; Feng Qian; David Murdock; William E. Brownell; Bahman Anvari

    2004-01-01

    Information on plasma membrane (PM) and cell wall mechanical properties is important for many biophysical applications, especially for those, which involve cells, undergoing significant mechanical stress (red blood cells, outer hair cells, fibrocytes, etc.). Optical tweezers is frequently used to study PM mechanics, particularly by pulling long PM tethers. One of the limitations on using optical tweezers to study cell

  19. Theory of magic optical traps for Zeeman-insensitive clock transitions in alkali-metal atoms

    SciTech Connect

    Derevianko, Andrei [Department of Physics, University of Nevada, Reno, Nevada 89557 (United States)

    2010-05-15

    Precision measurements and quantum-information processing with cold atoms may benefit from trapping atoms with specially engineered, 'magic' optical fields. At the magic trapping conditions, the relevant atomic properties remain immune to strong perturbations by the trapping fields. Here we develop a theoretical analysis of magic trapping for especially valuable Zeeman-insensitive clock transitions in alkali-metal atoms. The involved mechanism relies on applying a magic bias B field along a circularly polarized trapping laser field. We map out these B fields as a function of trapping laser wavelength for all commonly used alkalis. We also highlight a common error in evaluating Stark shifts of hyperfine manifolds.

  20. Entangled states of trapped atomic ions

    Microsoft Academic Search

    Rainer Blatt; David Wineland

    2008-01-01

    To process information using quantum-mechanical principles, the states of individual particles need to be entangled and manipulated. One way to do this is to use trapped, laser-cooled atomic ions. Attaining a general-purpose quantum computer is, however, a distant goal, but recent experiments show that just a few entangled trapped ions can be used to improve the precision of measurements. If

  1. A high-speed vertical optical trap for the mechanical testing of living cells at piconewton forces

    NASA Astrophysics Data System (ADS)

    Bodensiek, Kai; Li, Weixing; Sánchez, Paula; Nawaz, Schanila; Schaap, Iwan A. T.

    2013-11-01

    Although atomic force microscopy is often the method of choice to probe the mechanical response of (sub)micrometer sized biomaterials, the lowest force that can be reliably controlled is limited to ?0.1 nN. For soft biological samples, like cells, such forces can already lead to a strain large enough to enter the non-elastic deformation regime. To be able to investigate the response of single cells at lower forces we developed a vertical optical trap. The force can be controlled down to single piconewtons and most of the advantages of atomic force microscopy are maintained, such as the symmetrical application of forces at a wide range of loading rates. Typical consequences of moving the focus in the vertical direction, like the interferometric effect between the bead and the coverslip and a shift of focus, were quantified and found to have negligible effects on our measurements. With a fast responding force feedback loop we can achieve deformation rates as high as 50 ?m/s, which allow the investigation of the elastic and viscous components of very soft samples. The potential of the vertical optical trap is demonstrated by measuring the linearity of the response of single cells at very low forces and a high bandwidth of deformation rates.

  2. A high-speed vertical optical trap for the mechanical testing of living cells at piconewton forces.

    PubMed

    Bodensiek, Kai; Li, Weixing; Sánchez, Paula; Nawaz, Schanila; Schaap, Iwan A T

    2013-11-01

    Although atomic force microscopy is often the method of choice to probe the mechanical response of (sub)micrometer sized biomaterials, the lowest force that can be reliably controlled is limited to ?0.1 nN. For soft biological samples, like cells, such forces can already lead to a strain large enough to enter the non-elastic deformation regime. To be able to investigate the response of single cells at lower forces we developed a vertical optical trap. The force can be controlled down to single piconewtons and most of the advantages of atomic force microscopy are maintained, such as the symmetrical application of forces at a wide range of loading rates. Typical consequences of moving the focus in the vertical direction, like the interferometric effect between the bead and the coverslip and a shift of focus, were quantified and found to have negligible effects on our measurements. With a fast responding force feedback loop we can achieve deformation rates as high as 50 ?m/s, which allow the investigation of the elastic and viscous components of very soft samples. The potential of the vertical optical trap is demonstrated by measuring the linearity of the response of single cells at very low forces and a high bandwidth of deformation rates. PMID:24289404

  3. Highly reliable 2-bit\\/cell nitride trapping flash memory using a novel array-nitride-sealing (ANS) ONO process

    Microsoft Academic Search

    Yen-Hao Shih; S. C. Lee; H. T. Lue; M. D. Wu; T. H. Hsu; E. K. Lai; J. Y. Hsieh; C. W. Wu; L. W. Yang; Kuang Yeu Hsieh; K. C. Chen; R. Liu; Chih-Yuan Lu

    2005-01-01

    For nitride trapping NVM using BTBT-HH erase, hot hole injection generates Si\\/BOX interface traps that cause subthreshold swing degradation. During data retention time, the annealing of interface traps causes \\

  4. New vanadium trap proven in commercial trials

    SciTech Connect

    Dougan, T.J. (Grace Davison, Baltimore, MD (United States)); Alkemade, U.; Lakhanpal, B. (Grace Davison, Worms (Germany)); Boock, L.T. (Grace Davison, Columbia, MD (United States))

    1994-09-26

    A vanadium trap technology called RV4+ has demonstrated in a variety of commercial fluid catalytic cracking (FCC) units its ability to reduce vanadium on equilibrium catalyst by more than 20%. Reducing vanadium loading increases microactivity and zeolite surface area retention, confirming that RV4+ protects zeolites from vanadium deactivation. Sulfur competition had prevented some previous traps from working commercially, but was not a factor with the new trap. The technology can save refiners millions of dollars per year in catalyst costs, or allow them to process feeds containing higher vanadium concentrations. The paper discusses vanadium traps, deactivation mechanism, history of traps, vanadium mobility, intraparticle mobility, interparticle mobility, measuring performance, commercial results, sulfur competition, and economic value.

  5. Process for predicting structural performance of mechanical systems

    DOEpatents

    Gardner, D.R.; Hendrickson, B.A.; Plimpton, S.J.; Attaway, S.W.; Heinstein, M.W.; Vaughan, C.T.

    1998-05-19

    A process for predicting the structural performance of a mechanical system represents the mechanical system by a plurality of surface elements. The surface elements are grouped according to their location in the volume occupied by the mechanical system so that contacts between surface elements can be efficiently located. The process is well suited for efficient practice on multiprocessor computers. 12 figs.

  6. Investigating the rp-process with the Canadian Penning trap mass spectrometer

    Microsoft Academic Search

    J. A. Clark; R. C. Barber; B. Blank; C. Boudreau; F. Buchinger; J. E. Crawford; J. P. Greene; S. Gulick; J. C. Hardy; A. A. Hecht; A. Heinz; J. K. P. Lee; A. F. Levand; B. F. Lundgren; R. B. Moore; G. Savard; N. D. Scielzo; D. Seweryniak; K. S. Sharma; G. D. Sprouse; W. Trimble; J. Vaz; J. C. Wang; Y. Wang; B. J. Zabransky; Z. Zhou

    2005-01-01

    The Canadian Penning trap (CPT) mass spectrometer at the Argonne National Laboratory makes precise mass measurements of nuclides with short half-lives. Since the previous ENAM conference, many significant modifications to the apparatus were implemented to improve both the precision and efficiency of measurement, and now more than 60 radioactive isotopes have been measured with half-lives as short as one second

  7. Reaction between peroxynitrite and boronates: EPR spin-trapping, HPLC analyses, and quantum mechanical study of the free radical pathway

    PubMed Central

    Sikora, Adam; Zielonka, Jacek; Lopez, Marcos; Dybala-Defratyka, Agnieszka; Joseph, Joy; Marcinek, Andrzej; Kalyanaraman, Balaraman

    2013-01-01

    Recently we showed that peroxynitrite (ONOO?) reacts directly and rapidly with aromatic and aliphatic boronic acids (k ? 106 M?1s?1). Product analyses and substrate consumption data indicated that ONOO? reacts stoichiometrically with boronates, yielding the corresponding phenols as the major product (~85–90%), and the remaining products (10–15%) were proposed to originate from free radical intermediates (phenyl and phenoxyl radicals). Here we investigated in detail the minor, free radical pathway of boronate reaction with ONOO?. The electron paramagnetic resonance (EPR) spin-trapping technique was used to characterize the free radical intermediates formed from the reaction between boronates and ONOO?. Using 2-methyl-2-nitrosopropane (MNP) and 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) spin traps, phenyl radicals were trapped and detected. Although phenoxyl radicals were not detected, the positive effects of molecular oxygen, and inhibitory effects of hydrogen atom donors (acetonitrile, and 2-propanol) and general radical scavengers (GSH, NADH, ascorbic acid and tyrosine) on the formation of phenoxyl radical-derived nitrated product, suggest that phenoxyl radical was formed as the secondary species. We propose that the initial step of the reaction involves the addition of ONOO? to the boron atom in boronates. The anionic intermediate undergoes both heterolytic (major pathway) and homolytic (minor pathway) cleavage of the peroxy (O-O) bond to form phenol and nitrite as a major product (via a non-radical mechanism), or a radical pair PhB(OH)2O•?…•NO2 as a minor product. It is conceivable that phenyl radicals are formed by the fragmentation of PhB(OH)2O•? radical anion. According to the DFT quantum mechanical calculations, the energy barrier for the dissociation of PhB(OH)2O•? radical anion to form phenyl radicals is only a few kcal/mol, suggesting rapid and spontaneous fragmentation of PhB(OH)2O•? radical anion in aqueous media. Biological implications of the minor free radical pathway are discussed in the context of ONOO? detection, using the boronate probes. PMID:21434648

  8. BERNSTEIN PROCESSES, EUCLIDEAN QUANTUM MECHANICS AND INTEREST RATE MODELS

    E-print Network

    Lescot, Paul

    works with J.-C. Zambrini, of the link between euclidean quantum mechanics, Bernstein processes = as a new parameter. In Zambrini's Euclidean Quantum Mechanics (see e.g. [1]), this equation splits into : 2

  9. CHEMICAL AND PHYSICAL PROCESS AND MECHANISM MODELING

    EPA Science Inventory

    The goal of this task is to develop and test chemical and physical mechanisms for use in the chemical transport models of EPA's Models-3. The target model for this research is the Community Multiscale Air Quality (CMAQ) model. These mechanisms include gas and aqueous phase ph...

  10. Structure of a RING E3 Trapped in Action Reveals Ligation Mechanism for the Ubiquitin-like Protein NEDD8

    PubMed Central

    Scott, Daniel C.; Sviderskiy, Vladislav O.; Monda, Julie K.; Lydeard, John R.; Cho, Shein Ei; Harper, J. Wade; Schulman, Brenda A.

    2014-01-01

    SUMMARY Most E3 ligases use a RING domain to activate a thioester-linked E2~ubiquitin-like protein (UBL) intermediate and promote UBL transfer to a remotely bound target protein. Nonetheless, RING E3 mechanisms matching a specific UBL and acceptor lysine remain elusive, including for RBX1, which mediates NEDD8 ligation to cullins and >10% of all ubiquitination. We report the structure of a trapped RING E3-E2~UBL-target intermediate representing RBX1-UBC12~NEDD8-CUL1-DCN1, which reveals the mechanism of NEDD8 ligation and how a particular UBL and acceptor lysine are matched by a multifunctional RING E3. Numerous mechanisms specify cullin neddylation while preventing noncognate ubiquitin ligation. Notably, E2-E3-target and RING-E2~UBL modules are not optimized to function independently, but instead require integration by the UBL and target for maximal reactivity. The UBL and target regulate the catalytic machinery by positioning the RINGE2~UBL catalytic center, licensing the acceptor lysine, and influencing E2 reactivity, thereby driving their specific coupling by a multifunctional RING E3. PMID:24949976

  11. Mechanism of interferon-gamma production by monocytes stimulated with myeloperoxidase and neutrophil extracellular traps.

    PubMed

    Yamaguchi, Rui; Kawata, Jin; Yamamoto, Toshitaka; Ishimaru, Yasuji; Sakamoto, Arisa; Ono, Tomomichi; Narahara, Shinji; Sugiuchi, Hiroyuki; Hirose, Eiji; Yamaguchi, Yasuo

    2015-08-01

    Neutrophil extracellular traps (NETs) have an important role in antimicrobial innate immunity and release substances that may modulate the immune response. We investigated the effects of soluble factors from NETs and neutrophil granule proteins on human monocyte function by using the Transwell system to prevent cell-cell contact. NET formation was induced by exposing human neutrophils to phorbol myristate acetate (PMA). When monocytes were incubated with PMA alone, expression of interleukin (IL)-4, IL-6, IL-8, and tumor necrosis factor (TNF)-alpha mRNA was upregulated, but IL-10, IL-12, and interferon (IFN)-gamma mRNA were not detected. Incubation of monocytes with NETs enhanced the expression of IL-10 and IFN-gamma mRNA, but not IL-12 mRNA. Myeloperoxidase stimulated IFN-gamma production by monocytes in a dose-dependent manner. Both a nuclear factor-kappaB inhibitor (PDTC) and an intracellular calcium antagonist (TMB-8) prevented upregulation of IFN-gamma production. Neither a combined p38alpha and p38beta inhibitor (SB203580) nor an extracellular signal-regulated kinase inhibitor (PD98059) suppressed IFN-gamma production. Interestingly, a combined p38gamma and p38delta inhibitor (BIRB796) significantly decreased IFN-gamma production. These findings suggest that myeloperoxidase induces IFN-gamma production by monocytes via p38gamma/delta mitogen-activated protein kinase. PMID:26142328

  12. Trapping the ATP binding state leads to a detailed understanding of the F1-ATPase mechanism

    PubMed Central

    Nam, Kwangho; Pu, Jingzhi; Karplus, Martin

    2014-01-01

    The rotary motor enzyme FoF1-ATP synthase uses the proton-motive force across a membrane to synthesize ATP from ADP and Pi (H2PO4?) under cellular conditions that favor the hydrolysis reaction by a factor of 2 × 105. This remarkable ability to drive a reaction away from equilibrium by harnessing an external force differentiates it from an ordinary enzyme, which increases the rate of reaction without shifting the equilibrium. Hydrolysis takes place in the neighborhood of one conformation of the catalytic moiety F1-ATPase, whose structure is known from crystallography. By use of molecular dynamics simulations we trap a second structure, which is rotated by 40° from the catalytic dwell conformation and represents the state associated with ATP binding, in accord with single-molecule experiments. Using the two structures, we show why Pi is not released immediately after ATP hydrolysis, but only after a subsequent 120° rotation, in agreement with experiment. A concerted conformational change of the ?3?3 crown is shown to induce the 40° rotation of the ?-subunit only when the ?E subunit is empty, whereas with Pi bound, ?E serves as a latch to prevent the rotation of ?. The present results provide a rationalization of how F1-ATPase achieves the coupling between the small changes in the active site of ?DP and the 40° rotation of ?. PMID:25453082

  13. Mechanism of interaction of singlet oxygen with spin trap C-phenyl-N-tert-butylnitrone

    SciTech Connect

    Darmanyon, A.P.; Moger, G.

    1985-12-10

    The authors use pulse laser photolysis to study the mechanism of quenching of /sup 1/O/sub 2/ by C-phenyl-N-tert-butylnitrone (PBN) in benzene at 20 degrees C. PBN deactivates singlet oxygen quite effectively, mainly through a reversible electron transfer mechanism. In photochemical reactions in which photosensitizers with triplet state energy are used, the addition of PBN to the system should lead to a decrease in the yield of products through triplet-triplet energy transfer to the nitrone.

  14. Free Radical Mechanisms in Autoxidation Processes.

    ERIC Educational Resources Information Center

    Simic, Michael G.

    1981-01-01

    Discusses the use of steady-state radiation chemistry and pulse radiolysis for the generation of initial free radicals and formation of peroxy radicals in the autoxidation process. Provides information regarding the autoxidation process. Defines autoxidation reactions and antioxidant action. (CS)

  15. Quantum tunneling process and Zambrini's Euclidean quantum mechanics

    Microsoft Academic Search

    Mari Jibu; Kunio Yasue

    1992-01-01

    By adopting Zambrini's new Euclidean quantum mechanics, a theoretical procedure to describe the ill-defined problem of quantum tunneling processes studied recently in quantum cosmology is proposed. It is shown that the tunneling process from the vacuum state to a semi-classical state can be analyzed a priori in consrast with the conventional Copenhagen interpretation of quantum mechanics.

  16. Quantum tunneling process and Zambrini's Euclidean quantum mechanics

    NASA Astrophysics Data System (ADS)

    Jibu, Mari; Yasue, Kunio

    1992-11-01

    By adopting Zambrini's new Euclidean quantum mechanics, a theoretical procedure to describe the ill-defined problem of quantum tunneling processes studied recently in quantum cosmology is proposed. It is shown that the tunneling process from the vacuum state to a semi-classical state can be analyzed a priori in consrast with the conventional Copenhagen interpretation of quantum mechanics.

  17. Mass Measurements of Heavy ^252Cf Fission Fragments Near the r-Process Path with the Canadian Penning Trap

    NASA Astrophysics Data System (ADS)

    van Schelt, J.; Lascar, D.; Savard, G.; Clark, J. A.; Greene, J. P.; Levand, A. F.; Sun, T.; Zabransky, B. J.; Caldwell, S.; Sternberg, M.; Fallis, J.; Sharma, K. S.; Segel, R. E.; Li, G.

    2010-02-01

    Precision mass measurements of nuclides near the astrophysical r-process path are vital to reduce the uncertainties in the relevant neutron separation energies and the consequent abundance predictions. Before moving to CARIBU, the Canadian Penning Trap mass spectrometer at Argonne National Laboratory undertook a series of mass measurements of spontaneous fission products from a 150 ?Ci ^252Cf source in a previous large-volume gas catcher. Masses of 38 neutron-rich nuclides ranging from Z=51 to 64 were measured, many of which were closer to the r-process path than had previously been measured for these elements. Systematic deviations from the AME 2003 are seen over a wide range of elements, and possible effects of these deviations on the r process will be discussed. These measurements are being extended to even higher neutron excess at CARIBU. )

  18. Chemical Mechanical Planarization of Cu: Nanoscale Processes

    Microsoft Academic Search

    Michael Arthur; Kelly Fishbeck; Kara Muessig; James McDonald; Christine Williams; Daniel White; Deborah Koeck; Scott Perry; Heather Galloway

    2002-01-01

    Interconnect lines in state of the art integrated circuits are made of copper in a process that requires the repeated planarization of the copper layer. During this process the material is subjected to an aqueous slurry containing active chemicals, corrosion inhibitors and abrasive particles. A model slurry buffered to pH2, pH4 and pH6, contained nitric acid, silica particles and benzotriazole

  19. Diffusion and bulk flow in phloem loading: a theoretical analysis of the polymer trap mechanism for sugar transport in plants.

    PubMed

    Dölger, Julia; Rademaker, Hanna; Liesche, Johannes; Schulz, Alexander; Bohr, Tomas

    2014-10-01

    Plants create sugar in the mesophyll cells of their leaves by photosynthesis. This sugar, mostly sucrose, has to be loaded via the bundle sheath into the phloem vascular system (the sieve elements), where it is distributed to growing parts of the plant. We analyze the feasibility of a particular loading mechanism, active symplasmic loading, also called the polymer trap mechanism, where sucrose is transformed into heavier sugars, such as raffinose and stachyose, in the intermediary-type companion cells bordering the sieve elements in the minor veins of the phloem. Keeping the heavier sugars from diffusing back requires that the plasmodesmata connecting the bundle sheath with the intermediary cell act as extremely precise filters, which are able to distinguish between molecules that differ by less than 20% in size. In our modeling, we take into account the coupled water and sugar movement across the relevant interfaces, without explicitly considering the chemical reactions transforming the sucrose into the heavier sugars. Based on the available data for plasmodesmata geometry, sugar concentrations, and flux rates, we conclude that this mechanism can in principle function, but that it requires pores of molecular sizes. Comparing with the somewhat uncertain experimental values for sugar export rates, we expect the pores to be only 5%-10% larger than the hydraulic radius of the sucrose molecules. We find that the water flow through the plasmodesmata, which has not been quantified before, contributes only 10%-20% to the sucrose flux into the intermediary cells, while the main part is transported by diffusion. On the other hand, the subsequent sugar translocation into the sieve elements would very likely be carried predominantly by bulk water flow through the plasmodesmata. Thus, in contrast to apoplasmic loaders, all the necessary water for phloem translocation would be supplied in this way with no need for additional water uptake across the plasma membranes of the phloem. PMID:25375520

  20. Integrating Thermal Tools Into the Mechanical Design Process

    NASA Technical Reports Server (NTRS)

    Tsuyuki, Glenn T.; Siebes, Georg; Novak, Keith S.; Kinsella, Gary M.

    1999-01-01

    The intent of mechanical design is to deliver a hardware product that meets or exceeds customer expectations, while reducing cycle time and cost. To this end, an integrated mechanical design process enables the idea of parallel development (concurrent engineering). This represents a shift from the traditional mechanical design process. With such a concurrent process, there are significant issues that have to be identified and addressed before re-engineering the mechanical design process to facilitate concurrent engineering. These issues also assist in the integration and re-engineering of the thermal design sub-process since it resides within the entire mechanical design process. With these issues in mind, a thermal design sub-process can be re-defined in a manner that has a higher probability of acceptance, thus enabling an integrated mechanical design process. However, the actual implementation is not always problem-free. Experience in applying the thermal design sub-process to actual situations provides the evidence for improvement, but more importantly, for judging the viability and feasibility of the sub-process.

  1. Optical tweezers and multiphoton microscopies integrated photonic tool for mechanical and biochemical cell processes studies

    NASA Astrophysics Data System (ADS)

    de Thomaz, A. A.; Faustino, W. M.; Fontes, A.; Fernandes, H. P.; Barjas-Castro, M. d. L.; Metze, K.; Giorgio, S.; Barbosa, L. C.; Cesar, C. L.

    2007-09-01

    The research in biomedical photonics is clearly evolving in the direction of the understanding of biological processes at the cell level. The spatial resolution to accomplish this task practically requires photonics tools. However, an integration of different photonic tools and a multimodal and functional approach will be necessary to access the mechanical and biochemical cell processes. This way we can observe mechanicaly triggered biochemical events or biochemicaly triggered mechanical events, or even observe simultaneously mechanical and biochemical events triggered by other means, e.g. electricaly. One great advantage of the photonic tools is its easiness for integration. Therefore, we developed such integrated tool by incorporating single and double Optical Tweezers with Confocal Single and Multiphoton Microscopies. This system can perform 2-photon excited fluorescence and Second Harmonic Generation microscopies together with optical manipulations. It also can acquire Fluorescence and SHG spectra of specific spots. Force, elasticity and viscosity measurements of stretched membranes can be followed by real time confocal microscopies. Also opticaly trapped living protozoas, such as leishmania amazonensis. Integration with CARS microscopy is under way. We will show several examples of the use of such integrated instrument and its potential to observe mechanical and biochemical processes at cell level.

  2. Ultra-fast underwater suction traps

    PubMed Central

    Vincent, Olivier; Weißkopf, Carmen; Poppinga, Simon; Masselter, Tom; Speck, Thomas; Joyeux, Marc; Quilliet, Catherine; Marmottant, Philippe

    2011-01-01

    Carnivorous aquatic Utricularia species catch small prey animals using millimetre-sized underwater suction traps, which have fascinated scientists since Darwin's early work on carnivorous plants. Suction takes place after mechanical triggering and is owing to a release of stored elastic energy in the trap body accompanied by a very fast opening and closing of a trapdoor, which otherwise closes the trap entrance watertight. The exceptional trapping speed—far above human visual perception—impeded profound investigations until now. Using high-speed video imaging and special microscopy techniques, we obtained fully time-resolved recordings of the door movement. We found that this unique trapping mechanism conducts suction in less than a millisecond and therefore ranks among the fastest plant movements known. Fluid acceleration reaches very high values, leaving little chance for prey animals to escape. We discovered that the door deformation is morphologically predetermined, and actually performs a buckling/unbuckling process, including a complete trapdoor curvature inversion. This process, which we predict using dynamical simulations and simple theoretical models, is highly reproducible: the traps are autonomously repetitive as they fire spontaneously after 5–20 h and reset actively to their ready-to-catch condition. PMID:21325323

  3. Benchmarking Peer Production Mechanisms, Processes & Practices

    ERIC Educational Resources Information Center

    Fischer, Thomas; Kretschmer, Thomas

    2008-01-01

    This deliverable identifies key approaches for quality management in peer production by benchmarking peer production practices and processes in other areas. (Contains 29 footnotes, 13 figures and 2 tables.)[This report has been authored with contributions of: Kaisa Honkonen-Ratinen, Matti Auvinen, David Riley, Jose Pinzon, Thomas Fischer, Thomas…

  4. Mechanism in the reaction of cytochrome c oxidase with organic hydroperoxides: an ESR spin-trapping investigation.

    PubMed Central

    Chen, Yeong-Renn; Mason, Ronald P

    2002-01-01

    Organic hydroperoxides are of great utility in probing the reaction mechanism and the toxicological consequences of lipid peroxidation. In the present study, ESR spin-trapping was employed to investigate the peroxidation of mitochondrial cytochrome c oxidase (CcO) with t-butyl hydroperoxide (t-BuOOH) and cumene hydroperoxide (CumOOH). The spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) was used to detect the radical species formed from the reaction of CcO with t-BuOOH. The presence of t-BuOOH-derived alkoxyl radical (t-BuO*) as the primary radical indicates reductive scission of the O-O bond by CcO. The ESR signal of DMPO/*Ot-Bu can be partially abolished by cyanide, implying that the reductive cleavage involved the haem a(3)Cu(B) binuclear site of CcO. A nitroso spin trap, 2-methyl-2-nitrosopropane (MNP), was used to detect and identify radical species from the reaction of CcO with CumOOH. In addition to the t-BuOOH-derived methyl, hydroxylmethyl and tertiary carbon-centred radicals, a protein-derived radical was detected. The intensity of the ESR signal from the protein radical increased with the CumOOH concentration at low CumOOH/CcO ratios, with maximal intensity at a ratio of 100 mol of CumOOH/mol of CcO. The immobilized protein radical adduct of MNP was stable and persistent after dialysis; it was also resistant to proteolytic digestion, suggesting that it was formed in the transmembrane region, a region that is not accessible to proteases. Its signal was greatly enhanced when CcO cysteine residues were chemically modified by N-ethylmaleimide, when the tryptophan residues in CcO were oxidized by N-bromosuccimide, and when tyrosine residues on the surface of CcO were iodinated, showing that a radical equilibrium was established among the cysteine, tryptophan and tyrosine residues of the protein-centred radical. Pre-treatment of CcO with cyanide prevented detectable MNP adduct formation, confirming that the haem a(3)-Cu(B) binuclear centre was the initial reaction site. When the CcO was pre-treated with 10 mM (100 equivalents) of CumOOH, the enzyme activity decreased by more than 20%. This inhibition was persistent after dialysis, suggesting that the detected protein-centred radical was, in part, involved in the irreversible inactivation by CumOOH. Visible spectroscopic analysis revealed that the haem a of CcO was not affected during the reaction. However, the addition of pyridine to the reaction mixture under alkaline conditions resulted in the destruction of the haem centre of CcO, suggesting that its protein matrix rather than its haem a is the target of oxidative damage by the organic hydroperoxide. PMID:11931642

  5. Formation process and mechanical property of slickenside

    NASA Astrophysics Data System (ADS)

    Nishiwaki, T.; Ando, J.; Hirose, T.; Kagi, H.; Ohfuji, H.

    2013-12-01

    Slickenside is well-known microstructure created on fault surface as a shiny and smooth fault plane. However, its generation process and influence on fault behavior have not been studied in detail so far. In order to understand that, we conducted frictional experiments on Carrara marble using a rotary shear apparatus to produce artificial slickenside. Frictional experiments are performed on hollow and solid cylinders of Carrara marble at normal stress of 1.0, 2.0, 3.0 MPa (with hollow cylinders) and 5.0, 10.0 MPa (with solid cylinders), slip rate of 0.1 m/s, and displacement of up to 5 m. Before starting each experiment, the specimens are rotated at low slip rate (0.01 m/s) and low normal stress (0.3 MPa) to produce parallel and smooth slip surfaces. The results are followings: 1) Slickenside is formed in friction experiments even at low slip rate (0.1 m/s). 2) The slickenside is rather developed at higher normal stress and/or longer displacement conditions. 3) The slickenside is formed only on the ground tiny grains of calcite, which is produced on the slip surface during the initial stage of experiment. 4) The slickenside starts to form after the temperature of slip surface reaches ca. 100°C. 5) The frictional coefficient at lower normal stress such as 1.0, 2.0 and 3.0 MPa, is ca. 0.6, while at higher normal stress it decreases to ca. 0.2 with the development of slickenside. Based on these results, we infer the following formation process of the slickenside. The calcite grains on the slip surface are crushed to tiny powders at the initial stage of experiment. Then the powders are strongly squeezed by shearing and are sintered to form slickenside. This phenomenon is similar to that of tribofilm. The exact normal stress effect on the frictional coefficient is presently under investigation.

  6. Faculty Position in Mechanical Engineering Water Conservation in Industrial Processes

    E-print Network

    Faculty Position in Mechanical Engineering Water Conservation in Industrial Processes University for a tenure- track faculty position at the rank of Assistant Professor in the area of water conservation

  7. Bernstein processes, Euclidean Quantum Mechanics and Interest Rate Models

    E-print Network

    Lescot, Paul

    2009-01-01

    We give an exposition, following joint works with J.-C. Zambrini, of the link between Euclidean Quantum Mechanics, Bernstein processes and isovectors for the heat equation. A new application to Mathematical Finance is then discussed.

  8. Statistical mechanics of non-Markovian exclusion processes 

    E-print Network

    Concannon, Robert James

    2014-06-28

    The Totally Asymmetric Simple Exclusion Process (TASEP) is often considered one of the fundamental models of non-equilibrium statistical mechanics, due to its well understood steady state and the fact that it can exhibit ...

  9. Mechanical pretreatment of waste activated sludge for anaerobic digestion process

    Microsoft Academic Search

    In Wook Nah; Yun Whan Kang; Kyung-Yub Hwang; Woong-Ki Song

    2000-01-01

    This research investigated the effect of mechanical pretreatment of waste activated sludge (WAS) to a pilot scale (2000 l) anaerobic digestion process. Mechanical pretreatment of WAS by jetting and colliding to a collision-plate at 30 bar made the sludge solubilized, as examining some parameters before and after mechanical pretreatment of waste-activated sludge; for example, Suspended Solid (SS), Soluble Chemical Oxygen Demand

  10. Mechanisms That Interchange Axial and Equatorial Atoms in Fluxional Processes

    NSDL National Science Digital Library

    The Berry pseudorotation is a classical mechanism for interchanging axial and equatorial ligands in molecules with trigonal bipyramidal geometry. Teaching this mechanism presents particular pedagogic problems due to both its dynamic and three dimensional character. The approach taken here illustrates these processes using interactive animations embedded in a Web page and overcomes many limitations of a printed page.

  11. Implementation of a fully automated process purge-and-trap gas chromatograph at an environmental remediation site

    SciTech Connect

    Blair, D.S.; Morrison, D.J.

    1997-03-01

    The AQUASCAN, a commercially available, fully automated purge-and-trap gas chromatograph from Sentex Systems Inc., was implemented and evaluated as an in-field, automated monitoring system of contaminated groundwater at an active DOE remediation site in Pinellas, FL. Though the AQUASCAN is designed as a stand alone process analytical unit, implementation at this site required additional hardware. The hardware included a sample dilution system and a method for delivering standard solution to the gas chromatograph for automated calibration. As a result of the evaluation the system was determined to be a reliable and accurate instrument. The AQUASCAN reported concentration values for methylene chloride, trichloroethylene, and toluene in the Pinellas ground water were within 20% of reference laboratory values.

  12. A generalized message-passing mechanism for communicating sequential processes

    SciTech Connect

    Lenders, P.M.

    1988-06-01

    Bidirectional message-passing (bi-io), a new symmetric communication mechanism for concurrent processes is introduced and developed. The mechanism is symmetric in the sense that, in one atomic action, a message is transmitted in each direction between two processes. For some applications (tree structure, systolic arrays), this method is shown to have several advantages over conventional synchronization and communication primitives (mainly conciseness of programs, absence of certain types of deadlock). The mechanism is rigorously defined with a CSP-like syntax and a weakest precondition semantics. Two systolic arrays are developed using bidirectional message-passing: a matrix-vector multiplier, and a palindrome recognizer.

  13. Thermo-Mechanical Processing Parameters for the INCONEL ALLOY 740

    SciTech Connect

    Ludtka, G.M.; Smith, G.

    2007-11-19

    In 2000, a Cooperative Research and Development Agreement (CRADA) was undertaken between the Oak Ridge National Laboratory (ORNL) and the Special Metals Corporation (SMC) to determine the mechanical property response of the IN740 alloy to help establish thermo-mechanical processing parameters for the use of this alloy in supercritical and ultra-critical boiler tubes with the potential for other end uses. SMC had developed an alloy, commercially known as INCONEL alloy 740, which exhibited various beneficial physical, mechanical, and chemical properties. As part of SMC's on-going efforts to optimize this alloy for targeted boiler applications there was a need to develop an understanding of the thermo-mechanical response of the material, characterize the resulting microstructure from this processing, and possibly, utilize models to develop the appropriate processing scheme for this product.

  14. Generation Mechanism for Cyclostationary and Self-Similar Processes

    Microsoft Academic Search

    S. L. Nalbalwar; S. D. Joshi; R. K. Patney

    2006-01-01

    This paper proposes a generation mechanism for cyclostationary and self-similar processes. The proposed model extracts the information from the immediate coarser scale and adds the innovations to it to obtain the finer scale representation of the stochastic process. Basic block of the proposed model is the subband coder. By cascading the blocks of subband coder and passing white noise as

  15. Mechanical peeling of pumpkins. Part 2: Modeling of peeling process

    Microsoft Academic Search

    Bagher Emadi; M. H. Abbaspour-Fard; P. K. D. V. Yarlagadda

    2008-01-01

    A novel mechanical peeling process using an abrasive-cutter brush which applies both abrasive and cutting forces was modeled. An energy consumption model of the peeling process is required to optimize the main influential factors as well as to limit peeling waste and consumed energy. The input and output variables which could be industrially applicable were used. Three variables, namely rotational

  16. 40 CFR 408.30 - Applicability; description of the mechanized blue crab processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Applicability; description of the mechanized blue crab processing subcategory. 408.30...PROCESSING POINT SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30...Applicability; description of the mechanized blue crab processing subcategory. The...

  17. 40 CFR 408.30 - Applicability; description of the mechanized blue crab processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Applicability; description of the mechanized blue crab processing subcategory. 408.30...PROCESSING POINT SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30...Applicability; description of the mechanized blue crab processing subcategory. The...

  18. 40 CFR 408.30 - Applicability; description of the mechanized blue crab processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Applicability; description of the mechanized blue crab processing subcategory. 408.30...PROCESSING POINT SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30...Applicability; description of the mechanized blue crab processing subcategory. The...

  19. 40 CFR 408.30 - Applicability; description of the mechanized blue crab processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Applicability; description of the mechanized blue crab processing subcategory. 408.30...PROCESSING POINT SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30...Applicability; description of the mechanized blue crab processing subcategory. The...

  20. 40 CFR 408.30 - Applicability; description of the mechanized blue crab processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Applicability; description of the mechanized blue crab processing subcategory. 408.30...PROCESSING POINT SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30...Applicability; description of the mechanized blue crab processing subcategory. The...

  1. Venus fly trap

    NSDL National Science Digital Library

    Paul Lenz (None; )

    2006-01-26

    Time-lapse photos or video show progressions from the start of an event to the end of the event. These time-lapse photos illustrate the growth of a single Venus fly trap. Biological processes require time.

  2. 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.

  3. Adiabatic shear mechanisms for the hard cutting process

    NASA Astrophysics Data System (ADS)

    Yue, Caixu; Wang, Bo; Liu, Xianli; Feng, Huize; Cai, Chunbin

    2015-05-01

    The most important consequence of adiabatic shear phenomenon is formation of sawtooth chip. Lots of scholars focused on the formation mechanism of sawtooth, and the research often depended on experimental approach. For the present, the mechanism of sawtooth chip formation still remains some ambiguous aspects. This study develops a combined numerical and experimental approach to get deeper understanding of sawtooth chip formation mechanism for Polycrystalline Cubic Boron Nitride (PCBN) tools orthogonal cutting hard steel GCr15. By adopting the Johnson-Cook material constitutive equations, the FEM simulation model established in this research effectively overcomes serious element distortions and cell singularity in high strain domain caused by large material deformation, and the adiabatic shear phenomenon is simulated successfully. Both the formation mechanism and process of sawtooth are simulated. Also, the change features regarding the cutting force as well as its effects on temperature are studied. More specifically, the contact of sawtooth formation frequency with cutting force fluctuation frequency is established. The cutting force and effect of cutting temperature on mechanism of adiabatic shear are investigated. Furthermore, the effects of the cutting condition on sawtooth chip formation are researched. The researching results show that cutting feed has the most important effect on sawtooth chip formation compared with cutting depth and speed. This research contributes a better understanding of mechanism, feature of chip formation in hard turning process, and supplies theoretical basis for the optimization of hard cutting process parameters.

  4. Steam Trap Application 

    E-print Network

    Murphy, J. J.

    1982-01-01

    configuration between the steam user and trap inlet. Most applications are of the gravity drainage type. To facilitate proper trap opera tion and system protection, certain guidelines should be followed. Some equipment designs require syphon and/or lift.... Production/or Process (a) Steam heating a liquid,indirectly (b) Steam heating a gas, indirectly (c) Steam heating a solid or slurry,indirect ly (d) Steam heating a solid, directly 2. Protection (a) Steam line drip (b) Steam Tracing Process...

  5. Mechanisms of genome instability induced by RNA processing defects

    PubMed Central

    Chan, Yujia A.; Hieter, Philip

    2014-01-01

    The role of normal transcription and RNA processing in maintaining genome integrity is becoming increasingly appreciated in organisms ranging from bacteria to humans. Several mutations in RNA biogenesis factors have been implicated in human cancers, but the mechanisms and potential connections to tumor genome instability are not clear. Here we discuss how RNA processing defects could destabilize genomes through mutagenic R-loop structures and by altering expression of genes required for genome stability. A compelling body of evidence now suggests that researchers should be directly testing these mechanisms in models of human cancer. PMID:24794811

  6. Improving Software Development Process through Economic Mechanism Design

    NASA Astrophysics Data System (ADS)

    Yilmaz, Murat; O'Connor, Rory V.; Collins, John

    We introduce the novel concept of applying economic mechanism design to software development process, and aim to find ways to adjust the incentives and disincentives of the software organization to align them with the motivations of the participants in order to maximize the delivered value of a software project. We envision a set of principles to design processes that allow people to be self motivated but constantly working toward project goals. The resulting economic mechanism will rely on game theoretic principles (i.e. Stackelberg games) for leveraging the incentives, goals and motivation of the participants in the service of project and organizational goals.

  7. Hybrid Mechanical Systems

    E-print Network

    Philipp Treutlein; Claudiu Genes; Klemens Hammerer; Martino Poggio; Peter Rabl

    2015-01-06

    We discuss hybrid systems in which a mechanical oscillator is coupled to another (microscopic) quantum system, such as trapped atoms or ions, solid-state spin qubits, or superconducting devices. We summarize and compare different coupling schemes and describe first experimental implementations. Hybrid mechanical systems enable new approaches to quantum control of mechanical objects, precision sensing, and quantum information processing.

  8. Mechanistic, kinetic, and processing aspects of tungsten chemical mechanical polishing

    NASA Astrophysics Data System (ADS)

    Stein, David

    This dissertation presents an investigation into tungsten chemical mechanical polishing (CMP). CMP is the industrially predominant unit operation that removes excess tungsten after non-selective chemical vapor deposition (CVD) during sub-micron integrated circuit (IC) manufacture. This work explores the CMP process from process engineering and fundamental mechanistic perspectives. The process engineering study optimized an existing CMP process to address issues of polish pad and wafer carrier life. Polish rates, post-CMP metrology of patterned wafers, electrical test data, and synergy with a thermal endpoint technique were used to determine the optimal process. The oxidation rate of tungsten during CMP is significantly lower than the removal rate under identical conditions. Tungsten polished without inhibition during cathodic potentiostatic control. Hertzian indenter model calculations preclude colloids of the size used in tungsten CMP slurries from indenting the tungsten surface. AFM surface topography maps and TEM images of post-CMP tungsten do not show evidence of plow marks or intergranular fracture. Polish rate is dependent on potassium iodate concentration; process temperature is not. The colloid species significantly affects the polish rate and process temperature. Process temperature is not a predictor of polish rate. A process energy balance indicates that the process temperature is predominantly due to shaft work, and that any heat of reaction evolved during the CMP process is negligible. Friction and adhesion between alumina and tungsten were studied using modified AFM techniques. Friction was constant with potassium iodate concentration, but varied with applied pressure. This corroborates the results from the energy balance. Adhesion between the alumina and the tungsten was proportional to the potassium iodate concentration. A heuristic mechanism, which captures the relationship between polish rate, pressure, velocity, and slurry chemistry, is presented. In this mechanism, the colloid reacts with the chemistry of the slurry to produce active sites. These active sites become inactive by removing tungsten from the film. The process repeats when then inactive sites are reconverted to active sites. It is shown that the empirical form of the heuristic mechanism fits all of the data obtained. The mechanism also agrees with the limiting cases that were investigated.

  9. New Optimization Strategy for Chemical Mechanical Polishing Process

    Microsoft Academic Search

    Gou-Jen Wang; Jau-Liang Chen; Ju-Yi Hwang

    2001-01-01

    In this study, a systematic approach to achieve a globally optimal Chemical Mechanical Polishing (CMP) process is carried out. In this new approach, the orthogonal array technique adopted from the Taguchi method is used to realize an efficiently experimental design. The RBFNF neural-fuzzy network is then applied to model the complex CMP process. The signal-to-noise ratio (S\\/N) analysis (ANOVA) technique

  10. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...description of the Alaskan mechanized salmon processing subcategory. 408.170...POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory § 408.170...description of the Alaskan mechanized salmon processing subcategory. The...

  11. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...description of the West Coast mechanized salmon processing subcategory. 408.190...SOURCE CATEGORY West Coast Mechanized Salmon Processing Subcategory § 408.190...description of the West Coast mechanized salmon processing subcategory. The...

  12. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...description of the Alaskan mechanized salmon processing subcategory. 408.170...POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory § 408.170...description of the Alaskan mechanized salmon processing subcategory. The...

  13. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...description of the West Coast mechanized salmon processing subcategory. 408.190...SOURCE CATEGORY West Coast Mechanized Salmon Processing Subcategory § 408.190...description of the West Coast mechanized salmon processing subcategory. The...

  14. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...description of the Alaskan mechanized salmon processing subcategory. 408.170...POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory § 408.170...description of the Alaskan mechanized salmon processing subcategory. The...

  15. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...description of the West Coast mechanized salmon processing subcategory. 408.190...SOURCE CATEGORY West Coast Mechanized Salmon Processing Subcategory § 408.190...description of the West Coast mechanized salmon processing subcategory. The...

  16. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...description of the Alaskan mechanized salmon processing subcategory. 408.170...POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory § 408.170...description of the Alaskan mechanized salmon processing subcategory. The...

  17. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...description of the West Coast mechanized salmon processing subcategory. 408.190...SOURCE CATEGORY West Coast Mechanized Salmon Processing Subcategory § 408.190...description of the West Coast mechanized salmon processing subcategory. The...

  18. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...description of the West Coast mechanized salmon processing subcategory. 408.190...SOURCE CATEGORY West Coast Mechanized Salmon Processing Subcategory § 408.190...description of the West Coast mechanized salmon processing subcategory. The...

  19. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...description of the Alaskan mechanized salmon processing subcategory. 408.170...POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory § 408.170...description of the Alaskan mechanized salmon processing subcategory. The...

  20. Magnetic trapping of neutrons

    PubMed

    Huffman; Brome; Butterworth; Coakley; Dewey; Dzhosyuk; Golub; Greene; Habicht; Lamoreaux; Mattoni; McKinsey; Wietfeldt; Doyle

    2000-01-01

    Accurate measurement of the lifetime of the neutron (which is unstable to beta decay) is important for understanding the weak nuclear force and the creation of matter during the Big Bang. Previous measurements of the neutron lifetime have mainly been limited by certain systematic errors; however, these could in principle be avoided by performing measurements on neutrons stored in a magnetic trap. Neutral-particle and charged-particle traps are widely used for studying both composite and elementary particles, because they allow long interaction times and isolation of particles from perturbing environments. Here we report the magnetic trapping of neutrons. The trapping region is filled with superfluid 4He, which is used to load neutrons into the trap and as a scintillator to detect their decay. Neutrons in the trap have a lifetime of 750(+330)(-200) seconds, mainly limited by their beta decay rather than trap losses. Our experiment verifies theoretical predictions regarding the loading process and magnetic trapping of neutrons. Further refinement of this method should lead to improved precision in the neutron lifetime measurement. PMID:10638750

  1. Internet Auction Processes and Mechanisms Timothy L. Y. Leung

    E-print Network

    Knottenbelt, William J.

    Internet Auction Processes and Mechanisms by Timothy L. Y. Leung Submitted to the Department COLLEGE LONDON June 2012 c Timothy L. Y. Leung, MMXII. All rights reserved. The author hereby grants to Imperial College London permission to reproduce and distribute publicly paper and electronic copies

  2. The Schroedinger Problem, Levy Processes Noise in Relativistic Quantum Mechanics

    Microsoft Academic Search

    Piotr Garbaczewski; John R. Klauder; Robert Olkiewicz

    1995-01-01

    The main purpose of the paper is an essentially probabilistic analysis of relativistic quantum mechanics. It is based on the assumption that whenever probability distributions arise, there exists a stochastic process that is either responsible for temporal evolution of a given measure or preserves the measure in the stationary case. Our departure point is the so-called Schr\\\\\\

  3. Sequential processing mechanics modeling for a model IC package

    Microsoft Academic Search

    Jianjun Wang; Sheng Liu

    1997-01-01

    In this paper, a nonlinear finite element framework was established for processing mechanics modeling of electronic packaging assemblies and layered manufacturing. In particular, topological change was considered in order to model the sequential steps during a typical integrated circuit (IC) package assembly. Geometric and material nonlinearity, temperature dependent material properties were considered. Different stress free temperatures for different elements in

  4. Biologically Inspired Mechanisms for Processing Sensor Rich Environments

    Microsoft Academic Search

    Charles J. Hannon

    2002-01-01

    Biological organisms use a combination of attention and arousal to control the amount of sensory data being sent to their central nervous system's higher order processing. We propose using what neuroscience has learned about these natural mechanisms to construct a biologically inspired model of how sensor input can be filtered and fused in a large-scale DAI system. We then show

  5. Trapping and Modification Processes of Noble Gases and Nitrogen in Meteorites and Their Parent Bodies

    NASA Astrophysics Data System (ADS)

    Wieler, R.; Busemann, H.; Franchi, I. A.

    We review the inventories of primordial noble gases and nitrogen in meteorites, their carrier phases, how and where they may have been incorporated, as well as processes modifying their abundances on meteorite parent bodies. Some of the many distinct noble gas and nitrogen components have an isotopic composition very different from that in the Sun. These components reside in presolar grains. "Anomalous" noble gas and nitrogen components thus are used to infer parent stars of presolar grains as well as theories of stellar nucleosynthesis. Other noble gas components have an isotopic signature roughly similar to the solar composition. Some of these "normal" components are also carried by presolar grains and probably approximately represent the average isotopic composition of their parent stars. Carriers of other normal components remain ill-defined and their origin unclear. Their isotopic identity was possibly established in the solar nebula, but it appears increasingly likely that this often also happened earlier somewhere in the presolar molecular cloud. Apart from allowing us to study meteorite formation, primordial noble gases and nitrogen also are important tracers to constrain the metamorphic history of meteorite parent bodies.

  6. Early Olfactory Processing in Drosophila: Mechanisms and Principles

    PubMed Central

    Wilson, Rachel I.

    2014-01-01

    In the olfactory system of Drosophila melanogaster, it is relatively straightforward to make in vivo measurements of activity in neurons corresponding to targeted processing. This, together with the numerical simplicity of the Drosophila olfactory system, has produced rapid gains in our understanding of Drosophila olfaction. This review summarizes the neurophysiology of the first two layers of this system: the peripheral olfactory receptor neurons and their postsynaptic targets in the antennal lobe. We now understand in some detail the cellular and synaptic mechanisms that shape odor representations in these neurons. Together, these mechanisms imply that interesting neural adaptations to environmental statistics have occurred and place some fundamental constraints on early sensory processing that pose challenges for higher brain regions. These findings suggest some general principles with broad relevance to early sensory processing in other modalities. PMID:23841839

  7. Trapping Coyotes 

    E-print Network

    Texas Wildlife Services

    2008-04-15

    to livestock and crops in Texas. Damage Coyotes normally kill livestock by biting them around the throat. To determine if an ani- L-1908 4-08 mal has been killed by a coyote, carefully peel back the skin around the throat and look for tooth puncture wounds.... It is important that traps be kept clean and in good working condition. New traps have a thin coatingofgreaseandmustbecleanedbeforeuse. Boilinginwaterorsettingthetrapsouttoweath- er is usually sufficient to remove the grease. Old traps should be periodically...

  8. On the construction of point processes in statistical mechanics

    NASA Astrophysics Data System (ADS)

    Nehring, Benjamin; Poghosyan, Suren; Zessin, Hans

    2013-06-01

    We present a new approach to the construction of point processes of classical statistical mechanics as well as processes related to the Ginibre Bose gas of Brownian loops and to the dissolution in {R}^d of Ginibre's Fermi-Dirac gas of such loops. This approach is based on the cluster expansion method. We obtain the existence of Gibbs perturbations of a large class of point processes. Moreover, it is shown that certain "limiting Gibbs processes" are Gibbs in the sense of Dobrushin, Lanford, and Ruelle if the underlying potential is positive. Finally, Gibbs modifications of infinitely divisible point processes are shown to solve a new integration by parts formula if the underlying potential is positive.

  9. Trapping processes related to iron and carbon doping in AlGaN/GaN power HEMTs

    NASA Astrophysics Data System (ADS)

    Meneghini, M.; Bisi, D.; Rossetto, I.; De Santi, C.; Stocco, A.; Hilt, O.; Bahat-Treidel, E.; Wuerfl, J.; Rampazzo, F.; Meneghesso, G.; Zanoni, E.

    2015-03-01

    This paper reviews our recent results on the impact of iron and carbon compensation on the dynamic performance of GaN-HEMTs; based on pulsed and transient characterization, we demonstrate that: (i) the use of Fe-doping may lead to a significant current collapse, due to the presence of a trap with activation energy Ea=0.6eV. We discuss the properties of this trap and its physical origin; (ii) high C-doping levels may favor dynamic Ron increase, due to the presence of a trap level located at Ev+0.84 eV. The effect of this trap can be significantly reduced through the use of a double heterostructure.

  10. Holographic optical trapping.

    PubMed

    Grier, David G; Roichman, Yael

    2006-02-10

    Holographic optical tweezers use computer-generated holograms to create arbitrary three-dimensional configurations of single-beam optical traps that are useful for capturing, moving, and transforming mesoscopic objects. Through a combination of beam-splitting, mode-forming, and adaptive wavefront correction, holographic traps can exert precisely specified and characterized forces and torques on objects ranging in size from a few nanometers to hundreds of micrometers. Offering nanometer-scale spatial resolution and real-time reconfigurability, holographic optical traps provide unsurpassed access to the microscopic world and have found applications in fundamental research, manufacturing, and materials processing. PMID:16512529

  11. Holographic optical trapping

    SciTech Connect

    Grier, David G.; Roichman, Yael

    2006-02-10

    Holographic optical tweezers use computer-generated holograms to create arbitrary three-dimensional configurations of single-beam optical traps that are useful for capturing, moving, and transforming mesoscopic objects. Through a combination of beam-splitting, mode-forming, and adaptive wavefront correction, holographic traps can exert precisely specified and characterized forces and torques on objects ranging in size from a few nanometers to hundreds of micrometers. Offering nanometer-scale spatial resolution and real-time reconfigurability, holographic optical traps provide unsurpassed access to the microscopic world and have found applications in fundamental research, manufacturing, and materials processing.

  12. 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

  13. Inhibition of BPA degradation by serum as a hydroxyl radical scavenger and an Fe trapping agent in Fenton process.

    PubMed

    Sajiki, Junko; Masumizu, Toshiki

    2004-10-01

    Identification of reactive oxygen species (ROS) that contribute to bisphenol-A (BPA) degradation and monitoring of BPA at various concentrations in human serum under Fenton reaction conditions were carried out using electron spin resonance (ESR) spectrophotometry and high performance liquid chromatography with electrochemical detection (HPLC-ECD). BPA recovery decreased with increasing Fe concentration and time, both with a Fenton reaction using Fe(II), and with a Fenton-like reaction using Fe(III). In these reactions, BPA dose-dependently decreased the intensity of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO)-*OH, up to 1 microg/ml BPA, and no change in DMPO-O(2)(?-) intensity was observed. The decrease in BPA recovery was inhibited strongly by addition of serum under Fenton-like reaction conditions, and there was a negative correlation between turbidity and BPA recovery. To clarify the mechanism by which serum inhibits BPA degradation, the relationship between BPA recovery and sample turbidity, and characteristics of the precipitates were investigated using spectrophotometry and X-ray analysis. The precipitate formed in the serum-containing sample consisted of C, S, O, P and Fe. BPA degradation was also inhibited under Fenton-like reaction conditions in phosphate buffered saline (PBS), and a precipitate consisting of O, P, and Fe appeared. Precipitates also appeared in authentic albumin and gamma-globulin when sulfate was added with Fenton reagents. After precipitate removal, both Fe and protein concentrations in the supernatant of the protein solutions with sulfate decreased with increasing Fe addition. We demonstrate here that hydroxyl radical generation from Fenton or Fenton-like reactions can degrade BPA, and that serum strongly inhibits BPA degradation, not only by competing with BPA for hydroxyl radicals, but also by trapping Fe with oxidative components present in the serum. PMID:15312722

  14. Process Improvement Through Tool Integration in Aero-Mechanical Design

    NASA Technical Reports Server (NTRS)

    Briggs, Clark

    2010-01-01

    Emerging capabilities in commercial design tools promise to significantly improve the multi-disciplinary and inter-disciplinary design and analysis coverage for aerospace mechanical engineers. This paper explores the analysis process for two example problems of a wing and flap mechanical drive system and an aircraft landing gear door panel. The examples begin with the design solid models and include various analysis disciplines such as structural stress and aerodynamic loads. Analytical methods include CFD, multi-body dynamics with flexible bodies and structural analysis. Elements of analysis data management, data visualization and collaboration are also included.

  15. Process Mechanics of Low Plasticity Burnishing of Nitinol Alloy

    NASA Astrophysics Data System (ADS)

    Fu, C. H.; Guo, Y. B.; McKinney, J.; Wei, X. T.

    2012-12-01

    Nitinol alloys have received considerable attention in biomedical and aerospace applications. Surface integrity of Nitinol devices by various manufacturing processes is crucial for their functionality. Low plasticity burnishing (LPB) is very promising to modify surface integrity due to its unique capability to adjust material properties down to the deep subsurface on the order of a few millimeters. Burnishing mechanics is essential to understand its effect on surface properties. The depth and width of burnished surface materials are characterized. A three-dimensional finite element simulation has been developed to incorporate the superelastic mechanical behavior of Nitinol. The simulation predictions are validated with the experimental results. The contact stresses, residual stresses, and strain profiles are investigated to better understand burnishing mechanics.

  16. Deployment Process, Mechanization, and Testing for the Mars Exploration Rovers

    NASA Technical Reports Server (NTRS)

    Iskenderian, Ted

    2004-01-01

    NASA's Mar Exploration Rover (MER) robotic prospectors were produced in an environment of unusually challenging schedule, volume, and mass restrictions. The technical challenges pushed the system s design towards extensive integration of function, which resulted in complex system engineering issues. One example of the system's integrated complexity can be found in the deployment process for the rover. Part of this process, rover "standup", is outlined in this paper. Particular attention is given to the Rover Lift Mechanism's (RLM) role and its design. Analysis methods are presented and compared to test results. It is shown that because prudent design principles were followed, a robust mechanism was created that minimized the duration of integration and test, and enabled recovery without perturbing related systems when reasonably foreseeable problems did occur. Examples of avoidable, unnecessary difficulty are also presented.

  17. Investigation of formation mechanisms of chips in orthogonal cutting process

    NASA Astrophysics Data System (ADS)

    Ma, W.

    2012-08-01

    This work investigates the formation mechanisms of chips in orthogonal cutting of mild steel and the transformation conditions between various morphology chips. It is supposed that the modeling material follows the Johnson-Cook constitutive model. In orthogonal cutting process, both the plastic flow and the instability behaviors of chip materials are caused by the plane strain loadings. Therefore, the general instability behaviors of materials in plane strain state are first analyzed with linear perturbation method and a universal instability criterion is established. Based on the analytical results, the formation mechanisms of chips and the transformation conditions between continuous and serrated chips are further studied by instability phase diagram method. The results show that the chip formation strongly depends on the intensity ratios between shear and normal stresses. The ratios of dissipative rates of plastic work done by compression and shear stresses govern the transformation from continuous to serrated chips. These results are verified by the numerical simulations on the orthogonal cutting process.

  18. The interplay between cell signaling and mechanics in developmental processes

    PubMed Central

    Miller, Callie Johnson; Davidson, Lance

    2014-01-01

    Force and stress production within embryos and organisms are crucial physical processes that direct morphogenesis. In addition, there is mounting evidence that biomechanical cues created by these processes guide cell behaviors and cell fates. Here we review key roles for biomechanics during development to directly shape tissues, provide positional information for cell fate decisions, and enable robust programs of development. Several recently identified molecular mechanisms suggest how cells and tissues might coordinate their responses to biomechanical cues. Lastly, we outline long-term challenges in integrating biomechanics with genetic analysis of developing embryos. PMID:24045690

  19. Neurotoxin mechanisms and processes relevant to Parkinson's disease: an update.

    PubMed

    Segura-Aguilar, Juan; Kostrzewa, Richard M

    2015-04-01

    The molecular mechanism responsible for degenerative process in the nigrostriatal dopaminergic system in Parkinson's disease (PD) remains unknown. One major advance in this field has been the discovery of several genes associated to familial PD, including alpha synuclein, parkin, LRRK2, etc., thereby providing important insight toward basic research approaches. There is an consensus in neurodegenerative research that mitochon dria dysfunction, protein degradation dysfunction, aggregation of alpha synuclein to neurotoxic oligomers, oxidative and endoplasmic reticulum stress, and neuroinflammation are involved in degeneration of the neuromelanin-containing dopaminergic neurons that are lost in the disease. An update of the mechanisms relating to neurotoxins that are used to produce preclinical models of Parkinson´s disease is presented. 6-Hydroxydopamine, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, and rotenone have been the most wisely used neurotoxins to delve into mechanisms involved in the loss of dopaminergic neurons containing neuromelanin. Neurotoxins generated from dopamine oxidation during neuromelanin formation are likewise reviewed, as this pathway replicates neurotoxin-induced cellular oxidative stress, inactivation of key proteins related to mitochondria and protein degradation dysfunction, and formation of neurotoxic aggregates of alpha synuclein. This survey of neurotoxin modeling-highlighting newer technologies and implicating a variety of processes and pathways related to mechanisms attending PD-is focused on research studies from 2012 to 2014. PMID:25631236

  20. The Schroedinger Problem, Levy Processes Noise in Relativistic Quantum Mechanics

    E-print Network

    P. Garbaczewski; J. R. Klauder; R. Olkiewicz

    1995-05-09

    The main purpose of the paper is an essentially probabilistic analysis of relativistic quantum mechanics. It is based on the assumption that whenever probability distributions arise, there exists a stochastic process that is either responsible for temporal evolution of a given measure or preserves the measure in the stationary case. Our departure point is the so-called Schr\\"{o}dinger problem of probabilistic evolution, which provides for a unique Markov stochastic interpolation between any given pair of boundary probability densities for a process covering a fixed, finite duration of time, provided we have decided a priori what kind of primordial dynamical semigroup transition mechanism is involved. In the nonrelativistic theory, including quantum mechanics, Feyman-Kac-like kernels are the building blocks for suitable transition probability densities of the process. In the standard "free" case (Feynman-Kac potential equal to zero) the familiar Wiener noise is recovered. In the framework of the Schr\\"{o}dinger problem, the "free noise" can also be extended to any infinitely divisible probability law, as covered by the L\\'{e}vy-Khintchine formula. Since the relativistic Hamiltonians $|\

  1. Does The Principle Of Equivalence Prevent Trapped Surfaces From Being Formed In The General Relativistic Collapse Process?

    E-print Network

    Darryl Leiter; Stanley Robertson

    2002-12-11

    It has been recently shown (Mitra,- astro-ph/9910408, astro-ph/0207056) that the timelike spherical collapse of a radiating, physical fluid in General Relativity, as seen by an interior co-moving observer at rest in the physical fluid, does not permit formation of ``trapped surfaces''. This followed from the fact that the formation of a trapped surface in a physical fluid would cause the timelike world lines of the collapsing fluid to become null at the would be trapped surface, thus violating the Principle of Equivalence in General Theory of Relativity. In this paper we generalize and extend this result by studying the problem from the point of view of the exterior Vaidya metric of a collapsing radiating fluid as seen by an exterior stationary observer, and find that the "no trapped surface condition" becomes g00 > 0 consistent with that obtained for the interior co-moving metric. Since we have shown that the Principle of Equivalence prevents trapped surfaces from being formed in collapsing, radiating objects, then true event horizons cannot exist and Galactic Black Hole Candidates (GBHC) must have physically observable intrinsic magnetic dipole moments. Because of this fact it follows (Robertson and Leiter - astro-ph/0102381, astro-ph/0208333) that GBHC can be consistently described, within the framework of General Relativity, in terms of a magneto-spheric eternally collapsing objects (MECO) without true event horizons.

  2. [Analysis on mechanism of the chemical-biological flocculation process].

    PubMed

    Zhang, Zhi-bin; Zhao, Jian-fu; Xia, Si-qing; Liu, Chang-qing; Wang, Xue-jiang

    2007-05-01

    Zeta potential, particle size distribution and molecular weight distribution of dissolved TOC were studied to elementarily disclose the mechanism of the chemical-biological flocculation (CBF) process to treat municipal wastewater. Chemically enhanced primary treatment (CEPT) process and primary sedimentation tank process were taken as the parallel-compared wastewater treatment processes. The experimental results show that under the same dosage, Zeta potential of the CBF process effluent is equal to that of the CEPT process, which indicates that flocculant in return sludge does not change the stabilization of particles in CBF reactor, and the biological flocculation is the key reason for CBF is superior to CEPT. In CBF process, good removal results are achieved for particles >10 microm and dissolved TOC with molecular weight >6 ku by chemical dosage, and biological flocculation can not only promote the removal of particles >10 microm and dissolved TOC with molecular weight >6 ku, but also have high capacity to remove small particles and dissolved TOC with small molecular weight, with the results that particles >3 tpm are removed completely and TOC with molecular weight of 2-6 ku are removed by 42.5% . PMID:17633167

  3. Lithography develop process electrostatic discharge effect mechanism study

    NASA Astrophysics Data System (ADS)

    Yang, Xiaosong; Ye, Yi Zhou; Zou, Yongxiang; Zhu, XiaoZheng

    2015-03-01

    Electrostatic discharge (ESD) problem resulting from charges on wafers is a serious concern in IC manufacturing. As is discovered in our paper, three types of defect, AA (active area) damage, IMD (Inter Metal Dielectric) crack and Via hole W corrosion that are confirmed to be induced by lithography process related ESD charging effect. We carefully studied the mechanism of these ESD charging effect by DOE splits and succeeded to dig out that these electric charge major comes from the lithography develop process. In the lithography coating and developing wafer process, the wafer will be at high spin speed at many of the steps which will easy help to store the electric charge on the wafer. In our study, the rinse step in developing process is the most key factor to store the electric charge on wafer. In generally, the higher rinse speed, the higher positive electric charge. Furthermore, we also discovered that the different step in develop rinse process have different impact on charge level, in which the acceleration and deceleration step has the highest charge voltage. As to minimize and eliminate the ESD damage in lithography process, we finally carry out the simplified recipe optimization solution which only need optimize for the develop rinse speed with different in-coming surface charge level and process application, so that can be easy implemented in the worldwide fabs.

  4. Simultaneous sample washing and concentration using a "trapping-and-releasing" mechanism of magnetic beads on a microfluidic chip.

    PubMed

    Ramadan, Qasem; Gijs, Martin A M

    2011-03-21

    Simultaneous washing and concentration of functionalized magnetic beads in a complex sample solution were demonstrated by applying a rotational magnetic actuation system to a microfluidic chip under continuous flow conditions. The rotation of periodically arranged small permanent magnets close to the fluidic channel carrying a magnetic bead suspension allows trapping and releasing of the beads along the fluidic channel in a periodical manner. Each trapping and releasing event resembles one washing cycle. A purification efficiency of magnetic beads out of a mixed magnetic and non-magnetic bead sample solution of 83±4% at a flow rate of 0.5 µL min(-1), and a magnetic bead recovery or concentration efficiency of 91±5% were achieved using a flow rate of 0.2 µL min(-1). The detection performance of the device was experimentally evaluated with two different bioassays, using either streptavidin-coated magnetic beads in combination with biotinylated fluorescent isothiocyanate (FITC), or a mouse antigen (Ag)-antibody (Ab) system. PMID:21270982

  5. 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

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

    PubMed

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

    2014-01-23

    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. 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 and 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

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

    SciTech Connect

    Ciurea, Magdalena Lidia, E-mail: ciurea@infim.ro; Lazanu, Sorina, E-mail: ciurea@infim.ro [National Institute for Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania)

    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.

  8. Application of a data-processing model to determine the optimal sampling conditions for liquid phase trapping of atmospheric carbonyl compounds.

    PubMed

    Perraud, V; François, S; Wortham, H; Jourdain, B; Houdier, S; Kardos, N

    2008-08-15

    The reactivity of two fluorescent derivatization reagents, 2-diphenyl-1,3-indandione-1-hydrazone (DIH) and 2-aminooxy-N-[3-(5-dimethylamino-naphtalene-1-sulfonamino)-propyl]-acetamide (dansylacetamidooxyamine, DNSAOA), was studied towards selected atmospheric carbonyl compounds. The results were compared to those obtained using the 2,4-dinitrophenylhydrazine (2,4-DNPH) UV-vis reagent, a standard well-established technique used to detect atmospheric carbonyl compounds. The experimental rate constant were integrated into a data-processing model developed in the laboratory to simulate the trapping efficiencies of a mist chamber device as a function of temperature, reagent and solvent type among others. The results showed that in an aqueous solution, DNSAOA exhibits a higher reactivity towards carbonyl compounds without the addition of an acidic catalyst than 2,4-DNPH. It was observed that DNSAOA can trap efficiently water-soluble gaseous compounds (for example formaldehyde). However, because of a high initial contamination of the reagent caused by the synthesis procedure used in this work, DNSAOA cannot be used in high concentrations. As a result, very low trapping efficiencies of less reactive water-insoluble gaseous compounds (acetone) using DNSAOA are observed. However, the use of an organic solvent such as acetonitrile improved the trapping efficiencies of the carbonyl compounds. In this case, using DIH as the derivatization reagent (DNSAOA is not soluble in acetonitrile), trapping efficiencies greater than 95% were obtained, similar to 2,4-DNPH. Moreover, fluorescence associated with DIH derivatives (detection limits 3.33 x 10(-8)M and 1.72x10(-8)M for formaldehyde and acetone, respectively) is further advantage of this method for the determination of carbonyl compounds in complex matrix compared to the classical UV-vis detection method (detection limits 3.20 x 10(-8)M and 2.9 x 10(-8)M for formaldehyde and acetone, respectively). PMID:18656665

  9. Mechanical Clogging Processes in Unconsolidated Porous Media Near Pumping Wells

    NASA Astrophysics Data System (ADS)

    de Zwart, B.; Schotting, R.; Hassanizadeh, M.

    2003-12-01

    In the Netherlands water supply companies produce over more than one billion cubic meters of drinking water every year. About 2500 water wells are used to pump up the groundwater from aquifers in the Dutch subsurface. More than 50% of these wells will encounter a number of technical problems during their lifetime. The main problem is the decrease in capacity due to well clogging. Clogging shows up after a number of operation years and results in extra, expensive cleaning operations and in early replacement of the pumping wells. This problem has been acknowledged by other industries, for example the metal, petroleum, beer industry and underground storage projects. Well clogging is the result of a number of interacting mechanisms creating a complex problem in the subsurface. In most clogging cases mechanical mechanisms are involved. A large number of studies have been performed to comprehend these processes. Investigations on mechanical processes are focused on transport of small particles through pores and deposition of particles due to physical or physical-chemical processes. After a period of deposition the particles plug the pores and decrease the permeability of the medium. Particle deposition in porous media is usually modelled using filtration theory. In order to get the dynamics of clogging this theory is not sufficient. The porous media is continuously altered due to deposition and mobilization. Therefore the capture characteristics will also continuously change and deposition rates will change in time. A new formula is derived to describe (re)mobilization of particles and allow changing deposition rates. This approach incorporates detachment and reattachment of deposited particles. This work also includes derivation of the filtration theory in radial coordinates. A comparison between the radial filtration theory and the new formula will be shown.

  10. Round robin measurements of the flux trapping properties of melt processed Sm-Ba-Cu-O bulk superconductors

    NASA Astrophysics Data System (ADS)

    Cardwell, D. A.; Murakami, M.; Zeisberger, M.; Gawalek, W.; Gonzalez-Arrabal, R.; Eisterer, M.; Weber, H. W.; Fuchs, G.; Krabbes, G.; Leenders, A.; Freyhardt, H. C.; Chaud, X.; Tournier, R.; Hari Babu, N.

    2004-10-01

    Scanning Hall probe round robin measurements of the trapped field of two CFRF-clad, epoxy resin-reinforced large grain samples of Sm-Ba-Cu-O fabricated at ISTEC-SRL by top seeded melt growth (TSMG) have been performed by five European laboratories over a two year period under the auspice of the Versailles Project on Advanced Materials and Standards (VAMAS) and Technical Committee 90 (TC90) of the International Electrotechnical Commission (IEC). This study completes the interim report of the round robin tests presented at the fourth PASREG Workshop, Jena, July 2003. The peak fields derived from flux profiles measured by the different groups are found to correlate to within 6% over the measurement period. The flux trapping ability of the samples, measured by the peak field in the upper surface, deteriorated over the period of measurement by around 2% and 1%, respectively. Overall the measurements suggest that the trapped flux profile is most sensitive to changes in magnetizing field, experimental geometry and the sample-Hall probe separation. As a result, variations in these parameters should be minimized during flux mapping. In general a magnetizing field of 1.75 times the maximum trapped field for field cooled (FC) samples is required to ensure complete magnetization of a homogeneous cylindrical sample with an aspect ratio of ?2.5, corresponding to the geometry of the samples measured here. Finally, 20 min relaxation time following magnetization was observed to be sufficient to yield consistent measurement of the peak trapped field within the error of the measurement, which was typically less than 4%. Other than the recommended magnetizing field of 3 T, which should be determined by aspect ratio, temperature and maximum trapped field rather than pre-defined, the experimental conditions were confirmed to lie within the guidelines described in a draft International Electrotechnical Commission (IEC) Technical Committee 90 (TC90) standardization document on flux mapping. On the basis of the present results the proposed 5% spread in measured trapped field and a 20 min relaxation period appear to be reasonable criteria for trapped field measurements performed at different laboratories.

  11. Plant uprooting by flow as a fatigue mechanical process

    NASA Astrophysics Data System (ADS)

    Perona, Paolo; Edmaier, Katharina; Crouzy, Benoît

    2015-04-01

    In river corridors, plant uprooting by flow mostly occurs as a delayed process where flow erosion first causes root exposure until residual anchoring balances hydrodynamic forces on the part of the plant that is exposed to the stream. Because a given plant exposure time to the action of the stream is needed before uprooting occurs (time-to-uprooting), this uprooting mechanism has been denominated Type II, in contrast to Type I, which mostly affect early stage seedlings and is rather instantaneous. In this work, we propose a stochastic framework that describes a (deterministic) mechanical fatigue process perturbed by a (stochastic) process noise, where collapse occurs after a given exposure time. We test the model using the experimental data of Edmaier (2014) and Edmaier et al. (submitted), who investigated vegetation uprooting by flow in the limit of low plant stem-to-sediment size ratio by inducing parallel riverbed erosion within an experimental flume. We first identify the proper timescale and lengthscale for rescaling the model. Then, we show that it describes well all the empirical cumulative distribution functions (cdf) of time-to-uprooting obtained under constant riverbed erosion rate and assuming additive gaussian process noise. By this mean, we explore the level of determinism and stochasticity affecting the time-to-uprooting for Avena sativa in relation to root anchoring and flow drag forces. We eventually ascribe the overall dynamics of the Type II uprooting mechanism to the memory of the plant-soil system that is stored by root anchoring, and discuss related implications thereof. References Edmaier, K., Uprooting mechansims of juvenile vegetation by flow erosion, Ph.D. thesis, EPFL, 2014. Edmaier, K., Crouzy, B. and P. Perona. Experimental characterization of vegetation uprooting by flow. J. of Geophys. Res. - Biogeosci., submitted

  12. 9 CFR 318.18 - Handling of certain material for mechanical processing.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 2010-01-01 false Handling of certain material for mechanical processing. 318.18 Section 318.18 Animals and Animal... General § 318.18 Handling of certain material for mechanical processing. Material to be processed into...

  13. 9 CFR 318.18 - Handling of certain material for mechanical processing.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 false Handling of certain material for mechanical processing. 318.18 Section 318.18 Animals and Animal... General § 318.18 Handling of certain material for mechanical processing. Material to be processed into...

  14. 9 CFR 318.18 - Handling of certain material for mechanical processing.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 false Handling of certain material for mechanical processing. 318.18 Section 318.18 Animals and Animal... General § 318.18 Handling of certain material for mechanical processing. Material to be processed into...

  15. 9 CFR 318.18 - Handling of certain material for mechanical processing.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 2011-01-01 false Handling of certain material for mechanical processing. 318.18 Section 318.18 Animals and Animal... General § 318.18 Handling of certain material for mechanical processing. Material to be processed into...

  16. 9 CFR 318.18 - Handling of certain material for mechanical processing.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 false Handling of certain material for mechanical processing. 318.18 Section 318.18 Animals and Animal... General § 318.18 Handling of certain material for mechanical processing. Material to be processed into...

  17. Primary Processes in the Action of Ionizing Radiations on Water: Formation And Reactivity of Self-Trapped Electrons (`Polarons')

    Microsoft Academic Search

    Joseph Weiss

    1960-01-01

    Recent evidence is reviewed which indicates that positive as well as ; negative ionic species formed from the water may be important in the radiation ; chemistry of aqueous systems. Evidence is presented that there are two reducing ; species present in solution, namely hydrogen atoms and electrons. The self-; trapped electrons in the dielectric medium (water) were tentatively identified

  18. Diffusion Processes in Phase Spaces and Quantum Mechanics

    E-print Network

    E. M. Beniaminov

    2008-03-18

    A diffusion process for charge distributions in a phase space is examined. The corresponding charge moves in a force field and under an action of a random field. There are the diffusion motions for coordinates and for momenta. In our model, an inner state of the charge is defined by a complex vector. The vector rotates with a great constant angular velocity with respect to the proper time of the charge. A state of the diffusion process is a (complex-valued) wave function on the phase space. As in quantum mechanics, we assume that, for the wave functions, the superposition principle holds. The diffusion process averages out vectors of inner states from different points of the phase space. A differential equation for this diffusion process is founded and examined. We demonstrate that the motion (described by this process) decomposes into a fast motion and a slow motion. The fast motion reduces an arbitrary wave function to a function from a subspace whose elements are parameterized by complex-valued functions of coordinates. The slow motion occurs in this subspace and it is described by the Schr\\''odinger equation. The parameters of the suggested model are estimated. The duration of the fast motion is of order $10^{-11}$ s.

  19. The Mechanical Transient Process at Asynchronous Motor Oscillating Mode

    NASA Astrophysics Data System (ADS)

    Antonovi?s, Uldis; Bražis, Viesturs; Greivulis, J?nis

    2009-01-01

    The research object is squirrel-cage asynchronous motor connected to single-phase sinusoidal. There are shown, that by connecting to the stator windings a certain sequence of half-period positive and negative voltage, a motor rotor is rotated, but three times slower than in the three-phase mode. Changing the connecting sequence of positive and negative half-period voltage to stator windings, motor can work in various oscillating modes. It is tested experimentally. The mechanical transient processes had been researched in rotation and oscillating modes.

  20. Neutron stars. [quantum mechanical processes associated with magnetic fields

    NASA Technical Reports Server (NTRS)

    Canuto, V.

    1978-01-01

    Quantum-mechanical processes associated with the presence of high magnetic fields and the effect of such fields on the evolution of neutron stars are reviewed. A technical description of the interior of a neutron star is presented. The neutron star-pulsar relation is reviewed and consideration is given to supernovae explosions, flux conservation in neutron stars, gauge-invariant derivation of the equation of state for a strongly magnetized gas, neutron beta-decay, and the stability condition for a neutron star.

  1. Hyporheic flow and transport processes: mechanisms, models, and biogeochemical implications

    USGS Publications Warehouse

    Boano, Fulvio; Harvey, Judson W.; Marion, Andrea; Packman, Aaron I.; Revelli, Roberto; Ridolfi, Luca; Anders, Wörman

    2014-01-01

    Fifty years of hyporheic zone research have shown the important role played by the hyporheic zone as an interface between groundwater and surface waters. However, it is only in the last two decades that what began as an empirical science has become a mechanistic science devoted to modeling studies of the complex fluid dynamical and biogeochemical mechanisms occurring in the hyporheic zone. These efforts have led to the picture of surface-subsurface water interactions as regulators of the form and function of fluvial ecosystems. Rather than being isolated systems, surface water bodies continuously interact with the subsurface. Exploration of hyporheic zone processes has led to a new appreciation of their wide reaching consequences for water quality and stream ecology. Modern research aims toward a unified approach, in which processes occurring in the hyporheic zone are key elements for the appreciation, management, and restoration of the whole river environment. In this unifying context, this review summarizes results from modeling studies and field observations about flow and transport processes in the hyporheic zone and describes the theories proposed in hydrology and fluid dynamics developed to quantitatively model and predict the hyporheic transport of water, heat, and dissolved and suspended compounds from sediment grain scale up to the watershed scale. The implications of these processes for stream biogeochemistry and ecology are also discussed."

  2. Trapped particle absorption by the ring of Jupiter

    NASA Technical Reports Server (NTRS)

    Fillius, W.

    1985-01-01

    The ring systems of Jupiter and Saturn, and their interaction with the magnetosphere were studied. Opportunities to improve the understanding of the sweeping effect of orbiting material on trapped radiation, and the use of this process to gain insight on both the trapped radiation and the target material are outlined. Within the cosmogony of Hannes Alfven, this mechanism is also the key to understanding the formation of many of the features of the Saturnian rings. A better understanding of the sweeping effect would also help to clarify this process.

  3. Thermo-mechanical Processing of TRIP-Aided Steels

    NASA Astrophysics Data System (ADS)

    Ranjan, Ravi; Beladi, Hossein; Singh, Shiv Brat; Hodgson, Peter D.

    2015-07-01

    The effects of the partial replacement of Si with Al and the addition of P on the microstructure and mechanical properties of experimental TRIP-aided steels subjected to different thermo-mechanical cycles were studied. Based on the available literature and thermodynamics-based calculations, three steels with different compositions were designed to obtain optimum results from a relatively low number of experiments. Different combinations of microstructure were developed through three different kinds of thermo-mechanical-controlled processing (TMCP) routes, and the corresponding tensile properties were evaluated. The results indicated that partial replacement of Si with Al improved the strength-ductility balance along with providing an improved variation in the incremental change in the strain-hardening exponent. However, the impact of the P addition was found to depend more on the final microstructure obtained by the different TMCP cycles. It has also been shown that an increase in the volume fraction of the retained austenite () or its carbon content () resulted in an improved strength-ductility balance, which can be attributed to better exploitation of the TRIP effect.

  4. Evolution of attention mechanisms for early visual processing

    NASA Astrophysics Data System (ADS)

    Müller, Thomas; Knoll, Alois

    2011-03-01

    Early visual processing as a method to speed up computations on visual input data has long been discussed in the computer vision community. The general target of a such approaches is to filter nonrelevant information from the costly higher-level visual processing algorithms. By insertion of this additional filter layer the overall approach can be speeded up without actually changing the visual processing methodology. Being inspired by the layered architecture of the human visual processing apparatus, several approaches for early visual processing have been recently proposed. Most promising in this field is the extraction of a saliency map to determine regions of current attention in the visual field. Such saliency can be computed in a bottom-up manner, i.e. the theory claims that static regions of attention emerge from a certain color footprint, and dynamic regions of attention emerge from connected blobs of textures moving in a uniform way in the visual field. Top-down saliency effects are either unconscious through inherent mechanisms like inhibition-of-return, i.e. within a period of time the attention level paid to a certain region automatically decreases if the properties of that region do not change, or volitional through cognitive feedback, e.g. if an object moves consistently in the visual field. These bottom-up and top-down saliency effects have been implemented and evaluated in a previous computer vision system for the project JAST. In this paper an extension applying evolutionary processes is proposed. The prior vision system utilized multiple threads to analyze the regions of attention delivered from the early processing mechanism. Here, in addition, multiple saliency units are used to produce these regions of attention. All of these saliency units have different parameter-sets. The idea is to let the population of saliency units create regions of attention, then evaluate the results with cognitive feedback and finally apply the genetic mechanism: mutation and cloning of the best performers and extinction of the worst performers considering computation of regions of attention. A fitness function can be derived by evaluating, whether relevant objects are found in the regions created. It can be seen from various experiments, that the approach significantly speeds up visual processing, especially regarding robust ealtime object recognition, compared to an approach not using saliency based preprocessing. Furthermore, the evolutionary algorithm improves the overall performance of the preprocessing system in terms of quality, as the system automatically and autonomously tunes the saliency parameters. The computational overhead produced by periodical clone/delete/mutation operations can be handled well within the realtime constraints of the experimental computer vision system. Nevertheless, limitations apply whenever the visual field does not contain any significant saliency information for some time, but the population still tries to tune the parameters - overfitting avoids generalization in this case and the evolutionary process may be reset by manual intervention.

  5. Editorial: Process to progress? Investigative trials, mechanism and clinical science.

    PubMed

    Green, Jonathan

    2015-01-01

    In 2002 Helena Kraemer and colleagues published an important article on the analysis of clinical trials in mental health, which advocated a planned focus on mechanisms to investigate the processes behind treatment effects. Kraemer et al. considered not only new approaches to mediation analysis, but also a theoretical approach to factors, both pre-treatment and during treatment, that might moderate this mediation. Trials should not just be about whether a treatment 'worked', but how it worked; with the results informing modification of the intervention for the next trial by discarding aspects that were not effective and reinforcing aspects that were - an iterative procedure towards greater effectiveness. Can we enjoy similar ambitions for complex interventions within mental health? It is not so long ago when the received wisdom within the clinical and much of the research community was that it was simply impossible in practice to mount randomised controlled trials relevant to the kind of psychosocial interventions we use in child and adolescent mental health (CAMHS). How different the situation is now, with burgeoning interest in a systematic evidence base for psychological treatment and the possibilities for unexpected advances (as well as unexpected harms). Nevertheless it is probably still fair to say that the systematic use of process and mechanism study within trials in our field is the exception rather than the rule. What are the possibilities and implications for our field? PMID:25529393

  6. Processing and nanostructure influences on mechanical properties of thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Schmidt, Robert David

    Thermoelectric (TE) materials are materials that can generate an electric current from a thermal gradient, with possible service in recovery of waste heat such as engine exhaust. Significant progress has been made in improving TE conversion efficiency, typically reported according to the figure of merit, ZT, with several recent papers publishing ZT values above 2. Furthermore, cost reductions may be made by the use of lower cost elements such as Mg, Si, Sn, Pb, Se and S in TE materials, while achieving ZT values between 1.3 and 1.8. To be used in a device, the thermoelectric material must be able to withstand the applied thermal and mechanical forces without failure. However, these materials are brittle, with low fracture toughness typically less than 1.5 MPa-m1/2, and often less than 0.5 MPa-m1/2. For comparison, window glass is approximately 0.75 MPa-m1/2. They have been optimized with nanoprecipitates, nanoparticles, doping, alterations in stoichiometry, powder processing and other techniques, all of which may alter the mechanical properties. In this study, the effect of SiC nanoparticle additions in Mg2Si, SnTe and Ag nanoparticle additions in the skutterudite Ba0.3Co 4Sb12 on the elastic moduli, hardness and fracture toughness are measured. Large changes (˜20%) in the elastic moduli in SnTe 1+x as a function of x at 0 and 0.016 are shown. The effect on mechanical properties of doping and precipitates of CdS or ZnS in a PbS or PbSe matrix have been reported. Changes in sintering behavior of the skutterudite with the Ag nanoparticle additions were explored. Possible liquid phase sintering, with associated benefits in lower processing temperature, faster densification and lower cost, has been shown. A technique has been proposed for determining additional liquid phase sintering aids in other TE materials. The effects of porosity, grain size, powder processing method, and sintering method were explored with YbAl3 and Ba0.3Co4Sb 12, with the porosity dependence of the elastic moduli reported. Only one other TE material has the porosity dependence of the elastic moduli previously reported in the literature, lead-antimony-silver-tellurium (LAST), and the effect of different powder processing and sintering methods has never been reported previously on TE materials.

  7. Synthesis of niobium aluminides using mechanically activated self-propagating high-temperature synthesis and mechanically activated annealing process

    Microsoft Academic Search

    V Gauthier; C Josse; F Bernard; E Gaffet; J. P Larpin

    1999-01-01

    The mechanically activated self-propagating high-temperature synthesis (MASHS) technique and the mechanically activated annealing process (M2AP) were used to produce NbAl3 intermetallic compound. The MASHS process results from the combination of two steps: first, a mechanical activation of the Nb+3Al powders mixture; second, a self-propagating high-temperature synthesis (SHS). The M2AP process also results from the combination of two steps: the first

  8. A method for trapping breeding adult American Oystercatchers

    USGS Publications Warehouse

    McGowan, C.P.; Simons, T.R.

    2005-01-01

    We present an efficient and effective method for trapping adult, breeding American Oystercatchers (Haematopus palliatus) that minimizes disturbance to nesting birds and the risk of trapping injuries. We used a remote controlled mechanical decoy to lure territorial adults to a leg-hold noose-mat trap. We trapped 25 birds over two seasons and were successful on 54% of our trapping attempts in 2003. We only trapped birds before the breeding season or between nesting attempts to reduce nest-site disturbance.

  9. Mechanical trapping of the nucleus on micropillared surfaces inhibits the proliferation of vascular smooth muscle cells but not cervical cancer HeLa cells.

    PubMed

    Nagayama, Kazuaki; Hamaji, Yumi; Sato, Yuji; Matsumoto, Takeo

    2015-07-16

    The interaction between cells and the extracellular matrix on a topographically patterned surface can result in changes in cell shape and many cellular functions. In the present study, we demonstrated the mechanical deformation and trapping of the intracellular nucleus using polydimethylsiloxane (PDMS)-based microfabricated substrates with an array of micropillars. We investigated the differential effects of nuclear deformation on the proliferation of healthy vascular smooth muscle cells (SMCs) and cervical cancer HeLa cells. Both types of cell spread normally in the space between micropillars and completely invaded the extracellular microstructures, including parts of their cytoplasm and their nuclei. We found that the proliferation of SMCs but not HeLa cells was dramatically inhibited by cultivation on the micropillar substrates, even though remarkable deformation of nuclei was observed in both types of cells. Mechanical testing with an atomic force microscope and a detailed image analysis with confocal microscopy revealed that SMC nuclei had a thicker nuclear lamina and greater expression of lamin A/C than those of HeLa cells, which consequently increased the elastic modulus of the SMC nuclei and their nuclear mechanical resistance against extracellular microstructures. These results indicate that the inhibition of cell proliferation resulted from deformation of the mature lamin structures, which might be exposed to higher internal stress during nuclear deformation. This nuclear stress-induced inhibition of cell proliferation occurred rarely in cancer cells with deformable nuclei. PMID:26054426

  10. Efficiently engineering pore-scale processes: The role of force dominance and topology during nonwetting phase trapping in porous media

    NASA Astrophysics Data System (ADS)

    Herring, Anna L.; Andersson, Linnéa; Schlüter, Steffen; Sheppard, Adrian; Wildenschild, Dorthe

    2015-05-01

    We investigate trapping of a nonwetting (NW) phase, air, within Bentheimer sandstone cores during drainage-imbibition flow experiments, as quantified on a three dimensional (3D) pore-scale basis via x-ray computed microtomography (X-ray CMT). The wetting (W) fluid in these experiments was deionized water doped with potassium iodide (1:6 by weight). We interpret these experiments based on the capillary-viscosity-gravity force dominance exhibited by the Bentheimer-air-brine system and compare to a wide range of previous drainage-imbibition experiments in different media and with different fluids. From this analysis, we conclude that viscous and capillary forces dominate in the Bentheimer-air-brine system as well as in the Bentheimer-supercritical CO2-brine system. In addition, we further develop the relationship between initial (post-drainage) NW phase connectivity and residual (post-imbibition) trapped NW phase saturation, while also taking into account initial NW phase saturation and imbibition capillary number. We quantify NW phase connectivity via a topological measure as well as by a statistical percolation metric. These metrics are evaluated for their utility and appropriateness in quantifying NW phase connectivity within porous media. Here, we find that there is a linear relationship between initial NW phase connectivity (as quantified by the normalized Euler number, ? ˆ) and capillary trapping efficiency; for a given imbibition capillary number, capillary trapping efficiency (residual NW phase saturation normalized by initial NW phase saturation) can decrease by up to 60% as initial NW phase connectivity increases from low connectivity (? ˆ ? 0) to very high connectivity (? ˆ ? 1). We propose that multiphase fluid-porous medium systems can be efficiently engineered to achieve a desired residual state (optimal NW phase saturation) by considering the dominant forces at play in the system along with the impacts of NW phase topology within the porous media, and we illustrate these concepts by considering supercritical CO2 sequestration scenarios.

  11. Experiments with an ion-neutral hybrid trap: cold charge-exchange collisions

    NASA Astrophysics Data System (ADS)

    Smith, W. W.; Goodman, D. S.; Sivarajah, I.; Wells, J. E.; Banerjee, S.; Côté, R.; Michels, H. H.; Mongtomery, J. A.; Narducci, F. A.

    2014-01-01

    Due to their large trap depths (˜1 eV or 10,000 K), versatility, and ease of construction, Paul traps have important uses in high-resolution spectroscopy, plasma physics, and precision measurements of fundamental constants. An ion-neutral hybrid trap consisting of two separate but spatially concentric traps [a magneto-optic trap (MOT) for the neutral species and a mass-selective linear Paul trap for the ionic species] is an ideal apparatus for sympathetic cooling. However, over the past few years, hybrid traps have proven most useful in measuring elastic and charge-exchange rate constants of ion-neutral collisions over a wide temperature range from kilo-Kelvin to nano-Kelvin. We report some initially surprising results from a hybrid trap system in our laboratory where we have loaded the Paul trap with Ca+ ions in the presence of a Na MOT (localized dense gas of cold Na atoms). We find a strong loss of Ca+ ions with MOT exposure, attributed to an exothermic, non-resonant ion-neutral charge-exchange process with an activation barrier, which leads to the formation of Na+ ions. We propose a detailed mechanism for this process. We obtain an estimated measure of the rate constant for this charge exchange of ˜2 × 10-11 cm3/s, much less than the Langevin rate, which suggests that the Langevin assumption of unit efficiency in the reaction region is not correct in this case.

  12. Chaining and extension mechanism for image processing software

    NASA Astrophysics Data System (ADS)

    Cok, David R.; Cok, Ronald S.

    1992-04-01

    A common image processing hardware configuration consists of fast, special-purpose hardware attached to a general-purpose computer. The special-purpose hardware performs the computationally-intensive processing. This works well for algorithms that have been hand- coded for the special hardware, and in situations where a complete compiler for the attached processor is available. However, the development of new algorithms requires composition of the basic, hand-coded operators and this suffers from problems of inefficiency in both memory usage and loop overhead. Chaining mechanisms allow the delayed execution of operations, with the potential for optimizing combinations of operations to reduce this inefficiency. Modern programming languages, such as C++, allow attractive implementations of chaining as the programming interface can be natural and intuitive with little syntactical overhead for the chaining constructs. The paper will discuss the philosophy and implementation of chaining and a method for building optimized, chained image processing constructs without a special-purpose language parser or compiler.

  13. Ion traps fabricated in a CMOS foundry

    NASA Astrophysics Data System (ADS)

    Mehta, K. K.; Eltony, A. M.; Bruzewicz, C. D.; Chuang, I. L.; Ram, R. J.; Sage, J. M.; Chiaverini, J.

    2014-07-01

    We demonstrate trapping in a surface-electrode ion trap fabricated in a 90-nm CMOS (complementary metal-oxide-semiconductor) foundry process utilizing the top metal layer of the process for the trap electrodes. The process includes doped active regions and metal interconnect layers, allowing for co-fabrication of standard CMOS circuitry as well as devices for optical control and measurement. With one of the interconnect layers defining a ground plane between the trap electrode layer and the p-type doped silicon substrate, ion loading is robust and trapping is stable. We measure a motional heating rate comparable to those seen in surface-electrode traps of similar size. This demonstration of scalable quantum computing hardware utilizing a commercial CMOS process opens the door to integration and co-fabrication of electronics and photonics for large-scale quantum processing in trapped-ion arrays.

  14. Ion traps fabricated in a CMOS foundry

    E-print Network

    K. K. Mehta; A. M. Eltony; C. D. Bruzewicz; I. L. Chuang; R. J. Ram; J. M. Sage; J. Chiaverini

    2014-06-13

    We demonstrate trapping in a surface-electrode ion trap fabricated in a 90-nm CMOS (complementary metal-oxide-semiconductor) foundry process utilizing the top metal layer of the process for the trap electrodes. The process includes doped active regions and metal interconnect layers, allowing for co-fabrication of standard CMOS circuitry as well as devices for optical control and measurement. With one of the interconnect layers defining a ground plane between the trap electrode layer and the p-type doped silicon substrate, ion loading is robust and trapping is stable. We measure a motional heating rate comparable to those seen in surface-electrode traps of similar size. This is the first demonstration of scalable quantum computing hardware, in any modality, utilizing a commercial CMOS process, and it opens the door to integration and co-fabrication of electronics and photonics for large-scale quantum processing in trapped-ion arrays.

  15. Ion traps fabricated in a CMOS foundry

    E-print Network

    Mehta, K K; Bruzewicz, C D; Chuang, I L; Ram, R J; Sage, J M; Chiaverini, J

    2014-01-01

    We demonstrate trapping in a surface-electrode ion trap fabricated in a 90-nm CMOS (complementary metal-oxide-semiconductor) foundry process utilizing the top metal layer of the process for the trap electrodes. The process includes doped active regions and metal interconnect layers, allowing for co-fabrication of standard CMOS circuitry as well as devices for optical control and measurement. With one of the interconnect layers defining a ground plane between the trap electrode layer and the p-type doped silicon substrate, ion loading is robust and trapping is stable. We measure a motional heating rate comparable to those seen in surface-electrode traps of similar size. This is the first demonstration of scalable quantum computing hardware, in any modality, utilizing a commercial CMOS process, and it opens the door to integration and co-fabrication of electronics and photonics for large-scale quantum processing in trapped-ion arrays.

  16. Adaptation processes in insect olfactory receptors. Mechanisms and behavioral significance.

    PubMed

    Kaissling, K E; Zack Strausfeld, C; Rumbo, E R

    1987-01-01

    Adaptation was studied in single olfactory receptor cells of male moths of Bombyx mori and Antheraea polyphemus. Receptor potential and nerve impulse generators have different and very likely, spatially separate adaptation mechanisms possibly located in the outer dendritic segment and the cell soma, respectively. Restricted portions of the receptor cell dendrite can be locally adapted. The impulse generator may exhibit at least two distinct adaptation processes with different kinetics, as deduced from a consideration of the phasic-tonic response and the different adaptation properties of each of these phases. The response characteristics of cells in the same sensillum are different. The "faster" responding cell types resolve odor pulses with frequencies up to 10 per second--a performance that is probably needed for orientation during flight toward a small odor source. PMID:3324874

  17. Formal mechanization of device interactions with a process algebra

    NASA Technical Reports Server (NTRS)

    Schubert, E. Thomas; Levitt, Karl; Cohen, Gerald C.

    1992-01-01

    The principle emphasis is to develop a methodology to formally verify correct synchronization communication of devices in a composed hardware system. Previous system integration efforts have focused on vertical integration of one layer on top of another. This task examines 'horizontal' integration of peer devices. To formally reason about communication, we mechanize a process algebra in the Higher Order Logic (HOL) theorem proving system. Using this formalization we show how four types of device interactions can be represented and verified to behave as specified. The report also describes the specification of a system consisting of an AVM-1 microprocessor and a memory management unit which were verified in previous work. A proof of correct communication is presented, and the extensions to the system specification to add a direct memory device are discussed.

  18. Medial Efferent Mechanisms in Children with Auditory Processing Disorders

    PubMed Central

    Mishra, Srikanta K.

    2014-01-01

    Auditory processing disorder (APD) affects about 2–5% of children. However, the nature of this disorder is poorly understood. Children with APD typically have difficulties in complex listening situations. One mechanism thought to aid in listening-in-noise is the medial olivocochlear (MOC) inhibition. The purpose of this review was to critically analyze the published data on MOC inhibition in children with APD to determine whether the MOC efferents are involved in these individuals. The otoacoustic emission (OAE) methods used to assay MOC reflex were examined in the context of the current understanding of OAE generation mechanisms. Relevant literature suggests critical differences in the study population and OAE methods. Variables currently known to influence MOC reflex measurements, for example, middle-ear muscle reflexes or OAE signal-to-noise ratio, were not controlled in most studies. The use of potentially weaker OAE methods and the remarkable heterogeneity across studies does not allow for a definite conclusion whether or not the MOC reflex is altered in children with APD. Further carefully designed studies are needed to confirm the involvement of MOC efferents in APD. Knowledge of efferent functioning in children with APD would be mechanistically and clinically beneficial. PMID:25386132

  19. Strengthening Mechanisms in Thermomechanically Processed NbTi-Microalloyed Steel

    NASA Astrophysics Data System (ADS)

    Kostryzhev, Andrii G.; Marenych, Olexandra O.; Killmore, Chris R.; Pereloma, Elena V.

    2015-05-01

    The effect of deformation temperature on microstructure and mechanical properties was investigated for thermomechanically processed NbTi-microalloyed steel with ferrite-pearlite microstructure. With a decrease in the finish deformation temperature at 1348 K to 1098 K (1075 °C to 825 °C) temperature range, the ambient temperature yield stress did not vary significantly, work hardening rate decreased, ultimate tensile strength decreased, and elongation to failure increased. These variations in mechanical properties were correlated to the variations in microstructural parameters (such as ferrite grain size, solid solution concentrations, precipitate number density and dislocation density). Calculations based on the measured microstructural parameters suggested the grain refinement, solid solution strengthening, precipitation strengthening, and work hardening contributed up to 32 pct, up to 48 pct, up to 25 pct, and less than 3 pct to the yield stress, respectively. With a decrease in the finish deformation temperature, both the grain size strengthening and solid solution strengthening increased, the precipitation strengthening decreased, and the work hardening contribution did not vary significantly.

  20. Alternative Interpretation of Low-Energy Nuclear Reaction Processes with Deuterated Metals Based on the Bose-Einstein Condensation Mechanism

    NASA Astrophysics Data System (ADS)

    Kim, Yeong E.; Passell, Thomas O.

    2006-02-01

    Recently, a generalization of the Bose-Einstein condensation (BEC) mechanism has been made to a ground-state mixture of two different species of positively charged bosons in harmonic traps. The theory has been used to describe (D + Li) reactions in the low energy nuclear reaction (LENR) processes in condensed matter and predicts that the (D + Li) reaction rates can be larger than (D + D) reaction rates by as much as a factor of ~50, implying that (D + Li) reactions may be occuring in addition to the (D + D) reactions. A survey of the existing data from LENR experiments is carried out to check the validity of the theoretical prediction. We conclude that there is compelling experimental evidence which support the theoretical prediction. New experimental tests of the theoretical prediction are suggested.

  1. Thermoelectrically cooled water trap

    DOEpatents

    Micheels, Ronald H. (Concord, MA)

    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.

  2. Coherence in Microchip Traps

    E-print Network

    Philipp Treutlein; Peter Hommelhoff; Tilo Steinmetz; Theodor W. Hänsch; Jakob Reichel

    2004-04-22

    We report the coherent manipulation of internal states of neutral atoms in a magnetic microchip trap. Coherence lifetimes exceeding 1 s are observed with atoms at distances of $5-130 \\mu$m from the microchip surface. The coherence lifetime in the chip trap is independent of atom-surface distance within our measurement accuracy, and agrees well with the results of similar measurements in macroscopic magnetic traps. Due to the absence of surface-induced decoherence, a miniaturized atomic clock with a relative stability in the $10^{-13}$ range can be realized. For applications in quantum information processing, we propose to use microwave near-fields in the proximity of chip wires to create potentials that depend on the internal state of the atoms.

  3. Charge Trapping in Organic Thin-Film Transistors

    NASA Astrophysics Data System (ADS)

    McLellan, Claire; Owen, Jack; Grimminger, Marsha; Anthony, John; Jurchescu, Oana

    2011-03-01

    Charge trapping in the bulk of the organic semiconductors and at interface with the gate dielectric and/or contacts is one of the determining factors governing charge transport in organic thin-film transistors (OTFTs). We explore the current-voltage characteristics in different charge density regimes and extract the field-effect mobility. The dependence of mobility on gate/drain voltage give us valuable insight into the mechanism of charge transport and the relevance of trapping states. We perform measurements on devices fabricated using different methods, such as spin-coating, drop-casting or spray-coating, on a silicon gate electrode, silicon dioxide gate dielectric, and gold source and drain contacts. We demonstrate that the performance of OTFTs is strongly dependent on processing details. We show that even when using the same processing method, we are able to systematically tune the charge trapping states by chemically modifying the contact and dielectric surfaces with self-assembly monolayers.

  4. Ohmic contacts for wide bandgap semiconductors: Processing, properties and mechanisms

    NASA Astrophysics Data System (ADS)

    Park, Mi-Ran

    Stable Ohmic contacts are essential for reliable operation of wide bandgap semiconductor electronic and optoelectronic devices. Such contacts have been made to molecular beam epitaxy (MBE) grown n-type and p-type ZnSe on (100) semi-insulating GaAs substrates and metalorganic chemical vapor deposition (MOCVD) grown p-type GaN on (0001) sapphire substrates. Various metals have been deposited by thermal evaporation and annealing techniques at different temperatures. Chemical etching and cleaning, plasma treatment using reactive ion etching (RIE), and cryogenic treatment in liquid nitrogen have been studied. Ion implantation was also performed to obtain highly doped materials. The electrical characteristics for the contacts were examined by the current versus voltage data and the specific contact resistance was determined by use of the transmission line method (TLM) for II-VI n-type and p-type ZnSe and the circular transmission line method (c-TLM) for III-V p-type GaN, respectively. Contacts formed by In/Au to n-type ZnSe and Cu/Au to p-type ZnSe showed the lowest specific contact resistance values of 1.04 x 10--2 Ocm2 and 1.67 x 10--1 Ocm 2, respectively. A nitrogen plasma treatment of the ZnSe surface prior to metallization was proven to lower the contact resistance to p-type ZnSe. Two different current flow mechanisms involving thermionic emission and thermionic field emission were shown for the Cu/Au contact to low doped p-ZnSe (1 x 1017 cm--3) and three involving thermionic emission, thermionic field emission, and tunneling for the Mg/Au contact to highly doped n-ZnSe (1.15 x 1019 cm--3). MOCVD grown p-type Mg-doped GaN with hole concentration of 1.41 x 1017 cm--3 was used to study Ohmic contacts to p-type GaN. The effects of the cryogenic process on improving Ohmic behavior (I-V linearity) and reducing the specific contact resistance were investigated and may result from a combination of the improved surface morphology and the recrystallizing of new compounds such as NiO and Au:Pd solid solution. The I-V-T measurement for both contacts had similar behavior and closely fit thermionic field emission current mechanisms with little deviation but dominant transport mechanisms were not clear since the contacts were practically Ohmic. (Abstract shortened by UMI.)

  5. 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. (Cornell); (Weill-Med)

    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.

  6. Investigating Human Computation Centric Information Processing Mechanism: An ERP Data Analysis Study

    Microsoft Academic Search

    S. Motomura; Akinori Hara; Ning Zhong; Shengfu Lu; Jing-Long Wu

    2007-01-01

    In the paper, we propose a multi-aspect data mining process for investigating a more whole human information process mechanism systematically. As an example to demonstrate the proposed mining process, we explain how to design the experiments of an ERP mental arithmetic task with visual stimuli for investigating human computation centric information processing mechanism, and describe how to do multi-aspect analysis

  7. Investigation of storage of ultra-cold neutrons in traps

    NASA Astrophysics Data System (ADS)

    Nesvizhevsky, V. V.; Strelkov, A. V.; Geltenbort, P.; Iaydjiev, P. S.

    1999-05-01

    It is known that losses of ultra-cold neutrons (UCN) from traps are due to the ?-decay, up scattering and absorption on a surface but we have identified for the first time a complementary mechanism. We suppose that this arises from an increase in energy of the neutrons resulting in an upper energy spectral cut-off which is about twice higher than that for initial stored neutrons. The total probability for such a process equals 10^{-5} per collision with a trap wall made of stainless steel without or with a Fomblin oil and grease coating.

  8. Antioxidants in heat-processed koji and the production mechanisms.

    PubMed

    Okutsu, Kayu; Yoshizaki, Yumiko; Ikeda, Natsumi; Kusano, Tatsuro; Hashimoto, Fumio; Takamine, Kazunori

    2015-11-15

    We previously developed antioxidative heat-processed (HP)-koji via two-step heating (55°C/2days?75°C/3days) of white-koji. In this study, we isolated antioxidants in HP-koji and investigated their formation mechanisms. The antioxidants were identified to be 5-hydroxymethyl furfural (HMF) and 5-(?-d-glucopyranosyloxymethyl)-2-furfural (GMF) based on nuclear magnetic resonance spectral analysis. HMF and GMF were not present in intact koji, but were formed by heating at 75°C. As production of these antioxidants was more effective by two-step heating than by constant heating at 55°C or 75°C, we presumed that the antioxidant precursors are derived enzymatically at 55°C and that the antioxidants are formed subsequently by thermal reaction at 75°C. The heating assay of saccharide solutions revealed glucose and isomaltose as HMF and GMF precursors, respectively, and thus the novel finding of GMF formation from isomaltose. Finally, HMF and GMF were effectively formed by two-step heating from glucose and isomaltose present in koji. PMID:25977038

  9. Trapping of charged particles by Bessel beams

    E-print Network

    Bialynicki-Birula, Iwo; Drozd, Nadbor

    2011-01-01

    There exist two well established methods to trap charged particles: the Penning trap and the Paul trap. The subject of this article is to present a third mechanism for trapping charged particles - trapping by beams of electromagnetic radiation. The essential role is played by the electric field configuration in the plane perpendicular to the beam axis (for nonrelativistic electrons, the magnetic field is less important). Particles are confined to the vicinity of the minimum-energy points. In particular, for beams of electromagnetic radiation carrying orbital angular momentum such points lie on the beam axis.

  10. Electron Trapping and Acceleration in Self-Modulated Laser Wakefields.

    NASA Astrophysics Data System (ADS)

    Hafizi, B.; Esarey, E.; Hubbard, R. F.; Ting, A.; Sprangle, P.; Moore, C. I.

    1997-11-01

    In a laser wakefield accelerator (LWFA) electrons trapped in a laser-excited, fast phase velocity plasma wave (wakefield) can gain significant energy. In the self-modulated LWFA regime, self-trapping and acceleration of plasma electrons has been observed in recent experiments.(A. Ting et al., Phys. Plasmas 4), 1889 (1997). One possible mechanism for self-trapping is wavebreaking of the plasma wakefield. However, analysis and simulations have shown that self-trapping can occur at wakefield amplitudes significantly below wavebreaking from the interaction of the wakefield with a slow phase velocity wave.(E. Esarey et al., Phys. Rev. Lett. (submitted).) In the self-modulated regime, the slow wave is produced by the beating of the pump laser field with Raman backscattered light. The beat wave can trap low energy electrons from the plasma and inject them into the wakefield for acceleration to high energy. We shall present simulations of the beat wave trapping process and compare with experimental results at NRL.

  11. Electron Trapping and Acceleration in Self-Modulated Laser Wakefields.

    NASA Astrophysics Data System (ADS)

    Esarey, Eric; Ting, A.; Hubbard, R. F.; Hafizi, B.; Moore, C. I.

    1998-04-01

    In a laser wakefield accelerator (LWFA) electrons trapped in a laser-excited, fast phase velocity plasma wave (wakefield) can gain significant energy. In the self-modulated LWFA regime, self-trapping and acceleration of plasma electrons has been observed in recent experiments.(A. Ting et al., Phys. Plasmas 4), 1889 (1997). One possible mechanism for self-trapping is wavebreaking of the plasma wakefield. However, analysis and simulations have shown that self-trapping can occur at wakefield amplitudes significantly below wavebreaking from the interaction of the wakefield with a slow phase velocity wave.(E. Esarey et al., Phys. Rev. Lett. (submitted).) In the self-modulated regime, the slow wave is produced by the beating of the pump laser field with Raman backscattered light. The beat wave can trap low energy electrons from the plasma and inject them into the wakefield for acceleration to high energy. We shall present simulations of the beat wave trapping process and compare with experimental results at NRL.

  12. Interaction of trapped ions with trapped atoms

    E-print Network

    Grier, Andrew T. (Andrew Todd)

    2011-01-01

    In this thesis, I present results from two Paul-trap based ion traps carried out in the Vuleti? laboratory: the Atom-Ion trap for collision studies between cold atoms and cold ions, and the Cavity-Array trap for studying ...

  13. A Study of Optimality Theory and the Human Sentence Processing Mechanism

    Microsoft Academic Search

    Rajvinder Singh

    2002-01-01

    A Study of Optimality Theory and the Human Sentence Processing Mechanism Rajvinder Singh Abstract: From a computational perspective, parsing is a very interesting phenomenon. All people do it quickly, and all people do it well. The history of cognitive science has been filled with attempts to explain the mechanisms that guide the human sentence processing mechanism (hf. HSPM). These have

  14. CO2-ECBM related coupled physical and mechanical transport processes

    NASA Astrophysics Data System (ADS)

    Gensterblum, Y.; Sartorius, M.; Busch, A.; Krooss, B. M.; Littke, R.

    2012-12-01

    The interrelation of cleat transport processes and mechanical properties was investigated by permeability tests at different stress levels (60% to 130% of in-situ stress) with sorbing (CH4, CO2) and inert gases (N2, Ar, He) on a subbituminous A coal from the Surat Basin, Queensland Australia (figure). From the flow tests under controlled triaxial stress conditions the Klinkenberg-corrected "true" permeability coefficients and the Klinkenberg slip factors were derived. The "true"-, absolute or Klinkenberg-corrected permeability depends on gas type. Following the approach of Seidle et al. (1992) the cleat volume compressibility (cf) was calculated from observed changes in apparent permeability upon variation of external stress (at equal mean gas pressures). The observed effects also show a clear dependence on gas type. Due to pore or cleat compressibility the cleat aperture decreases with increasing effective stress. Vice versa, with increasing mean pore pressure at lower confining pressure an increase in permeability is observed, which is attributed to a widening of cleat aperture. Non-sorbing gases like helium and argon show higher apparent permeabilities than sorbing gases like methane and CO2. Permeability coefficients measured with successively increasing mean gas pressures were consistently lower than those determined at decreasing mean gas pressures. The kinetics of matrix transport processes were studied by sorption tests on different particle sizes at various moisture contents and temperatures (cf. Busch et al., 2006). Methane uptake rates were determined from the pressure decline curves recorded for each particle-size fraction, and "diffusion coefficients" were calculated using several unipore and bidisperse diffusion models. While the CH4 sorption capacity of moisture-equilibrated coals was significantly lower (by 50%) than that of dry coals, no hysteresis was observed between sorption and desorption on dry and moisture-equilibrated samples and the sorption isotherms recorded for different particle sizes were essentially identical. The CH4 uptake rates were lower by a factor of two for moist coals than for dry coals. Busch, A., Gensterblum, Y., Krooss, B.M. and Siemons, N., 2006. Investigation of high-pressure selective adsorption/desorption behaviour of CO2 and CH4 on coals: An experimental study. International Journal of Coal Geology, 66(1-2): 53-68. Seidle, J.P., Jeansonne, M.W. and Erickson, D.J., 1992. Application of Matchstick Geometry to Stress-Dependent Permeability in Coals, SPE Rocky Mountain Regional Meeting, Casper, Wyoming.

  15. 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

  16. Representing SN1 Reaction Mechanism Using the Qualitative Process Theory

    E-print Network

    Bailey-Kellogg, Chris

    our chemistry students as modelers, rather when the representation and design is transformed. This paper presents an account for the design of qualitative models for the SN1 reaction mechanism using QPT to software could help to uphold student interests in learning reaction mechanism courses, and to improve

  17. Magnetic Trapping

    NSDL National Science Digital Library

    Mendez, J.

    This set of five web pages provides a non-mathematical introduction to the motion of charged particles in magnetic fields. These pages describe the "guiding center motion" which determines the motion of ions and electrons trapped in the Earth's magnetic field and in laboratory plasma devices. Also covered are gyration and mirroring, adiabatic invariance and drifts due to an electric field and gradients in the magnetic field intensity. This is part of the work "The Exploration of the Earth's Magnetosphere". A Spanish translation is available.

  18. Efficient collection of single photons emitted from a trapped ion into a single-mode fiber for scalable quantum-information processing

    SciTech Connect

    Kim, Taehyun; Maunz, Peter; Kim, Jungsang [Fitzpatrick Institute for Photonics, Electrical and Computer Engineering Department, Duke University, Durham, North Carolina 27708 (United States)

    2011-12-15

    Interference and coincidence detection of two photons emitted by two remote ions can lead to an entangled state, which is a critical resource for scalable quantum-information processing. Currently the success probabilities of experimental realizations of this protocol are mainly limited by low coupling efficiency of a photon emitted by an ion into a single-mode fiber. Here we consider two strategies to enhance the collection probability of a photon emitted from a trapped Yb{sup +} ion, using analytic methods that can be easily applied to other types of ions or neutral atoms. Our analysis shows that we can achieve fiber coupling efficiency of over 30% with an optical cavity made of a flat fiber tip and a spherical mirror. We also investigate ways to increase the fiber coupling efficiency using high-numerical-aperture optics, and show that collection probability of over 15% is possible with proper control of aberration.

  19. Mouse Trap Racing in the Computer Age!

    NSDL National Science Digital Library

    2014-09-18

    Students design, build and evaluate a spring-powered mouse trap racer. For evaluation, teams equip their racers with an intelligent brick from a LEGO© MINDSTORMS© NXT Education Base Set and a HiTechnic© acceleration sensor. They use acceleration data collected during the launch to compute velocity and displacement vs. time graphs. In the process, students learn about the importance of fitting mathematical models to measurements of physical quantities, reinforce their knowledge of Newtonian mechanics, deal with design compromises, learn about data acquisition and logging, and carry out collaborative assessment of results from all participating teams.

  20. Multipass Friction-Stir Processing and its Effect on Mechanical Properties of Aluminum Alloy 5086

    NASA Astrophysics Data System (ADS)

    Ramesh, K. N.; Pradeep, S.; Pancholi, Vivek

    2012-11-01

    Twelve-pass friction stir processing (FSP), with 50 pct overlap was carried out on aluminum alloy 5086-O rolled plates to obtain total area of 40 × 150 mm2. Two methods of friction-stir processing, intermittent multipass friction stir processing (IMP), and continuous multipass stir processing (CMP) were carried out, and their effect on the mechanical properties of the processed material was studied. The results revealed that material subjected to IMP showed better mechanical properties compared with the material subjected to CMP. Also, a variation in mechanical properties was observed with an increase in the tool traverse speed for single-pass, CMP, and IMP types of processing.

  1. Charge carrier trapping into mobile, ionic defects in nanoporous ultra-low-k dielectric materials

    NASA Astrophysics Data System (ADS)

    Plawsky, Joel; Borja, Juan; Lu, Toh-Ming; Gill, William

    2014-03-01

    Reliability and robustness of low-k materials for advanced interconnects has become a major challenge for the continuous down-scaling of silicon semiconductor devices. Metal catalyzed time dependent breakdown (TDDB) is a major force preventing the integration of sub-32nm process technology nodes. We investigate how ionic species can become trapping centers (mobile defects) for charge carriers. A mechanism for describing and quantifying the trapping of charge carriers into mobile ions under bias and temperature stress is presented and experimentally investigated. The dynamics of trapping into ionic centers are severely impacted by temperature and species mass transport. After extended bias and temperature stress, the magnitude of charge trapping into ionic centers decreases asymptotically. Various processes such as the reduction of ionic species, moisture outgassing, and the inhibition of ionic drift via the distortion of local fields were investigated as possible cause for the reduction in charge trapping. Simulations suggest that built-in fields reduce the effect of an externally applied field in directing ionic drift, which can lead to the inhibition of the trapping mechanism. In addition, conduction mechanisms are investigated for reactive and inert electrodes. Seimconductor Research Corporation.

  2. Copper ion-exchanged channel waveguides optimization for optical trapping.

    PubMed

    Reshak, A H; Khor, K N; Shahimin, M M; Murad, S A Z

    2013-08-01

    Optical trapping of particles has become a powerful non-mechanical and non-destructive technique for precise particle positioning. The manipulation of particles in the evanescent field of a channel waveguide potentially allows for sorting and trapping of several particles and cells simultaneously. Channel waveguide designs can be further optimized to increase evanescent field prior to the fabrication process. This is crucial in order to make sure that the surface intensity is sufficient for optical trapping. Simulation configurations are explained in detail with specific simulation flow. Discussion on parameters optimization; physical geometry, optical polarization and wavelength is included in this paper. The effect of physical, optical parameters and beam spot size on evanescent field has been thoroughly discussed. These studies will continue toward the development of a novel copper ion-exchanged waveguide as a method of particle sorting, with biological cell propulsion studies presently underway. PMID:23726859

  3. Testing for Dark Matter Trapped in the Solar System

    NASA Technical Reports Server (NTRS)

    Krisher, Timothy P.

    1996-01-01

    We consider the possibility of dark matter trapped in the solar system in bound solar orbits. If there exist mechanisms for dissipating excess kinetic energy by an amount sufficient for generating bound solar orbits, then trapping of galactic dark matter might have taken place during formation of the solar system, or could be an ongoing process. Possible locations for acumulation of trapped dark matter are orbital resonances with the planets or regions in the outer solar system. It is posible to test for the presence of unseen matter by detecting its gravitational effects. Current results for dynamical limits obtained from analyses of planetary ephemeris data and spacecraft tracking data are presented. Possible future improvements are discussed.

  4. CO2-ECBM related coupled physical and mechanical transport processes

    NASA Astrophysics Data System (ADS)

    Gensterblum, Y.; Sartorius, M.; Busch, A.; Cumming, D.; Krooss, B. M.

    2012-04-01

    The interrelation of cleat transport processes and mechanical properties was investigated by permeability tests at different stress levels (60% to 130% of in-situ stress) with sorbing (CH4, CO2) and inert gases (N2, Ar, He) on a sub bituminous A coal from the Surat Basin, Queensland Australia. From the flow tests under controlled triaxial stress conditions the Klinkenberg-corrected "true" permeability coefficients and the Klinkenberg slip factors were derived. The "true"-, absolute or Klinkenberg corrected permeability shows a gas type dependence. Following the approach of Seidle et al. (1992) the cleat volume compressibility (cf) was calculated from observed changes in apparent permeability upon variation of external stress (at equal mean gas pressures). The observed effects also show a clear dependence on gas type. Due to pore or cleat compressibility the cleat aperture decreases with increasing effective stress. Vice versa we observe with increasing mean pressure at lower confining pressure an increase in permeability which we attribute to a cleat aperture widening. The cleat volume compressibility (cf) also shows a dependence on the mean pore pressure. Non-sorbing gases like helium and argon show higher apparent permeabilities than sorbing gases like methane. Permeability coefficients measured with successively increasing mean gas pressures were consistently lower than those determined at decreasing mean gas pressures. This permeability hysteresis is in accordance with results reported by Harpalani and McPherson (1985). The kinetics of matrix transport processes were studied by sorption tests on different particle sizes at various moisture contents and temperatures (cf. Busch et al., 2006). Methane uptake rates were determined from the pressure decline curves recorded for each particle-size fraction, and "diffusion coefficients" were calculated using several unipore and bidisperse diffusion models. While the CH4 sorption capacity of moisture-equilibrated coals was significantly lower (by 50%) than of dry coals, no hysteresis was observed between sorption and desorption on dry and moisture-equilibrated samples and the sorption isotherms recorded for different particle sizes were essentially identical. The CH4 uptake rates were lower by a factor of two for moist coals than for dry coals. Busch, A., Gensterblum, Y., Krooss, B.M. and Siemons, N., 2006. Investigation of high-pressure selective adsorption/desorption behaviour of CO2 and CH4 on coals: An experimental study. International Journal of Coal Geology, 66(1-2): 53-68. Harpalani, S. and McPherson, M.J., 1985. Effect of stress on permeability of coal. Quarterly Review of methane from coal seams technology, 3(2): 23-29. Seidle, J.P., Jeansonne, M.W. and Erickson, D.J., 1992. Application of Matchstick Geometry to Stress-Dependent Permeability in Coals, SPE Rocky Mountain Regional Meeting, Casper, Wyoming.

  5. CO2-ECBM related coupled physical and mechanical transport processes

    NASA Astrophysics Data System (ADS)

    Gensterblum, Yves; Satorius, Michael; Busch, Andreas; Krooß, Bernhard

    2013-04-01

    The interrelation of cleat transport processes and mechanical properties was investigated by permeability tests at different stress levels (60% to 130% of in-situ stress) with sorbing (CH4, CO2) and inert gases (N2, Ar, He) on a sub bituminous A coal from the Surat Basin, Queensland Australia. From the flow tests under controlled triaxial stress conditions the Klinkenberg-corrected "true" permeability coefficients and the Klinkenberg slip factors were derived. The "true"-, absolute or Klinkenberg corrected permeability shows a gas type dependence. Following the approach of Seidle et al. (1992) the cleat volume compressibility (cf) was calculated from observed changes in apparent permeability upon variation of external stress (at equal mean gas pressures). The observed effects also show a clear dependence on gas type. Due to pore or cleat compressibility the cleat aperture decreases with increasing effective stress. Vice versa we observe with increasing mean pressure at lower confining pressure an increase in permeability which we attribute to a cleat aperture widening. The cleat volume compressibility (cf) also shows a dependence on the mean pore pressure. Non-sorbing gases like helium and argon show higher apparent permeabilities than sorbing gases like methane. Permeability coefficients measured with successively increasing mean gas pressures were consistently lower than those determined at decreasing mean gas pressures. This permeability hysteresis is in accordance with results reported by Harpalani and McPherson (1985). The kinetics of matrix transport processes were studied by sorption tests on different particle sizes at various moisture contents and temperatures (cf. Busch et al., 2006). Methane uptake rates were determined from the pressure decline curves recorded for each particle-size fraction, and "diffusion coefficients" were calculated using several unipore and bidisperse diffusion models. While the CH4 sorption capacity of moisture-equilibrated coals was significantly lower (by 50%) than of dry coals, no hysteresis was observed between sorption and desorption on dry and moisture-equilibrated samples and the sorption isotherms recorded for different particle sizes were essentially identical. The CH4 uptake rates were lower by a factor of two for moist coals than for dry coals. Busch, A., Gensterblum, Y., Krooss, B.M. and Siemons, N., 2006. Investigation of high-pressure selective adsorption/desorption behaviour of CO2 and CH4 on coals: An experimental study. International Journal of Coal Geology, 66(1-2): 53-68. Harpalani, S. and McPherson, M.J., 1985. Effect of stress on permeability of coal. Quarterly Review of methane from coal seams technology, 3(2): 23-29. Seidle, J.P., Jeansonne, M.W. and Erickson, D.J., 1992. Application of Matchstick Geometry to Stress-Dependent Permeability in Coals, SPE Rocky Mountain Regional Meeting, Casper, Wyoming.

  6. Energy Conservation Thru Steam Trap Surveys and Preventive Maintenance Programs 

    E-print Network

    Boynton, T.; Dewhirst, B.

    1980-01-01

    This paper will deal with steam trap surveys and preventive maintenance programs and the energy savings that may be realized from such efforts. Trap survey organization, flexibility, simplicity, and mechanics will be reviewed, including the economic...

  7. Energy Conservation Thru Steam Trap Surveys and Preventive Maintenance Programs

    E-print Network

    Boynton, T.; Dewhirst, B.

    1980-01-01

    This paper will deal with steam trap surveys and preventive maintenance programs and the energy savings that may be realized from such efforts. Trap survey organization, flexibility, simplicity, and mechanics will be reviewed, including the economic...

  8. Dual-Pitch Processing Mechanisms in Primate Auditory Cortex

    E-print Network

    Bendor, Daniel

    Pitch, our perception of how high or low a sound is on a musical scale, is a fundamental perceptual attribute of sounds and is important for both music and speech. After more than a century of research, the exact mechanisms ...

  9. BERNSTEIN PROCESSES, EUCLIDEAN QUANTUM MECHANICS AND INTEREST RATE MODELS

    E-print Network

    an exposition, following joint works with J.-C. Zambrini, of the link between Euclidean Quantum Mechanics, and for m = 1: i t = - 2 2 2 q2 + V . We shall henceforth treat = as a new parameter. In Zambrini

  10. BERNSTEIN PROCESSES, EUCLIDEAN QUANTUM MECHANICS AND INTEREST RATE MODELS

    E-print Network

    Paris-Sud XI, Université de

    an exposition, following joint works with J.-C. Zambrini, of the link between euclidean quantum mechanics, and for m = 1: i t = - 2 2 2 q2 + V . We shall henceforth treat = as a new parameter. In Zambrini

  11. Novel small molecules disrupting Hec1/Nek2 interaction ablate tumor progression by triggering Nek2 degradation through a death-trap mechanism.

    PubMed

    Hu, C-M; Zhu, J; Guo, X E; Chen, W; Qiu, X-L; Ngo, B; Chien, R; Wang, Y V; Tsai, C Y; Wu, G; Kim, Y; Lopez, R; Chamberlin, A R; Lee, E Y-H P; Lee, W-H

    2015-03-01

    Hec1 (highly expressed in cancer 1) or Nek2 (NIMA-related kinase 2) is often overexpressed in cancers with poor prognosis. Both are critical mitotic regulators, and phosphorylation of Hec1 S165 by Nek2 is required for proper chromosome segregation. Therefore, inactivation of Hec1 and Nek2 by targeting their interaction with small molecules represents an ideal strategy for tackling these types of cancers. Here we showed that new derivatives of INH (inhibitor for Nek2 and Hec1 binding) bind to Hec1 at amino acids 394-408 on W395, L399 and K400 residues, effectively blocking Hec1 phosphorylation on S165 by Nek2, and killing cancer cells at the nanomolar range. Mechanistically, the D-box (destruction-box) region of Nek2 specifically binds to Hec1 at amino acids 408-422, immediately adjacent to the INH binding motif. Subsequent binding of Nek2 to INH-bound Hec1 triggered proteasome-mediated Nek2 degradation, whereas the Hec1 binding defective Nek2 mutant, Nek2 R361L, resisted INH-induced Nek2 degradation. This finding unveils a novel drug-action mechanism where the binding of INHs to Hec1 forms a virtual death-trap to trigger Nek2 degradation and eventually cell death. Furthermore, analysis of the gene expression profiles of breast cancer patient samples revealed that co-elevated expressions of Hec1 and Nek2 correlated with the shortest survival. Treatment of mice with this kind of tumor with INHs significantly suppressed tumor growth without obvious toxicity. Taken together, the new INH derivatives are suitable for translation into clinical application. PMID:24662830

  12. Thermo-Mechanical Processing in Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Schneider, Judy

    2003-01-01

    Friction stir welding is a solid-phase joining, or welding process that was invented in 1991 at The Welding Institute (TWI). The process is potentially capable of joining a wide variety of aluminum alloys that are traditionally difficult to fusion weld. The friction stir welding (FSW) process produces welds by moving a non-consumable rotating pin tool along a seam between work pieces that are firmly clamped to an anvil. At the start of the process, the rotating pin is plunged into the material to a pre-determined load. The required heat is produced by a combination of frictional and deformation heating. The shape of the tool shoulder and supporting anvil promotes a high hydrostatic pressure along the joint line as the tool shears and literally stirs the metal together. To produce a defect free weld, process variables (RPM, transverse speed, and downward force) and tool pin design must be chosen carefully. An accurate model of the material flow during the process is necessary to guide process variable selection. At MSFC a plastic slip line model of the process has been synthesized based on macroscopic images of the resulting weld material. Although this model appears to have captured the main features of the process, material specific interactions are not understood. The objective of the present research was to develop a basic understanding of the evolution of the microstructure to be able to relate it to the deformation process variables of strain, strain rate, and temperature.

  13. A tethering mechanism for length control in a processive carbohydrate polymerization

    E-print Network

    Gleeson, Joseph G.

    A tethering mechanism for length control in a processive carbohydrate polymerization John F. Maya, NY, and approved May 18, 2009 (received for review February 7, 2009) Carbohydrate polymers. galactofuranose mycobacteria polymerase polysaccharide processivity Carbohydrate polymers have myriad

  14. 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, we propose a detailed analysis of the catalytic mechanism. PMID:22529956

  15. Device Independent Process Control of Dielectric Chemical Mechanical Polishing

    E-print Network

    Boning, Duane S.

    these patterns and the pol- ishing behavior of a CMP tool make monitoring and controlling the process process on the pattern layout of the particular device being polished. The interactions between particularly difficult. Current techniques focus on the control of a few sites on a single type of layout being

  16. Controlled & automatic processing: behavior, theory, and biological mechanisms

    Microsoft Academic Search

    Walter Schneider; Jason M. Chein

    2003-01-01

    This paper provides an overview of developments in a dual processing theory of automatic and controlled processing that began with the empirical and theoretical work described by Schneider and Shiffrin (1977) and Shiffrin and Schneider (1977) over a quarter century ago. A review of relevant empirical findings suggests that there is a set of core behavioral phenomena reflecting differences between

  17. Coherence in Microchip Traps

    E-print Network

    Treutlein, P; Steinmetz, T; Hänsch, T W; Reichel, J; Treutlein, Philipp; Hommelhoff, Peter; Steinmetz, Tilo; H\\"ansch, Theodor W.; Reichel, Jakob

    2003-01-01

    We report the coherent manipulation of internal states of neutral atoms in a magnetic microchip trap. Coherence lifetimes exceeding 1 s are observed with atoms at distances of $4-130 \\mu$m from the microchip surface. The coherence lifetime in the microtrap is independent of atom-surface distance and agrees well with the results of similar measurements in macroscopic magnetic traps. Due to the absence of surface-induced decoherence, a miniaturized atomic clock with a relative stability in the $10^{-13}$ range can be realized. For applications in quantum information processing, we propose to use microwave near-fields in the proximity of chip wires to create potentials that depend on the internal state of the atoms.

  18. Dynamic Charge Carrier Trapping in Quantum Dot Field Effect Transistors.

    PubMed

    Zhang, Yingjie; Chen, Qian; Alivisatos, A Paul; Salmeron, Miquel

    2015-07-01

    Noncrystalline semiconductor materials often exhibit hysteresis in charge transport measurements whose mechanism is largely unknown. Here we study the dynamics of charge injection and transport in PbS quantum dot (QD) monolayers in a field effect transistor (FET). Using Kelvin probe force microscopy, we measured the temporal response of the QDs as the channel material in a FET following step function changes of gate bias. The measurements reveal an exponential decay of mobile carrier density with time constants of 3-5 s for holes and ?10 s for electrons. An Ohmic behavior, with uniform carrier density, was observed along the channel during the injection and transport processes. These slow, uniform carrier trapping processes are reversible, with time constants that depend critically on the gas environment. We propose that the underlying mechanism is some reversible electrochemical process involving dissociation and diffusion of water and/or oxygen related species. These trapping processes are dynamically activated by the injected charges, in contrast with static electronic traps whose presence is independent of the charge state. Understanding and controlling these processes is important for improving the performance of electronic, optoelectronic, and memory devices based on disordered semiconductors. PMID:26099508

  19. Mechanical properties of a fully dense polymer derived ceramic made by a novel pressure casting process

    Microsoft Academic Search

    Sandeep R Shah; Rishi Raj

    2002-01-01

    A new process has been developed for obtaining fully dense samples of silicon carbonitride (SiCN) from polymers. The process consists of two simple steps: cross-linking the liquid organic precursor under pressure, followed by controlled pyrolysis. Net shape processing is possible by casting the liquid into a mold before polymerization. The entire process is completed below 1000 °C. Basic mechanical properties

  20. Processing and mechanical characterization of lightweight polyurethane composites

    Microsoft Academic Search

    V. B. Chalivendra; A. Shukla; A. Bose; V. Parameswaran

    2003-01-01

    A simple procedure was established to fabricate polyurethane-cenosphere particulate composite materials. Composites having four different volume fractions of cenospheres (hollow ceramic microspheres) ranging from 10 to 40% in increments of 10% were prepared and their mechanical properties were evaluated. A predictive model to estimate the fracture toughness of the composite was developed. The dynamic constitutive behavior of the composite in

  1. Process Demands of Rejection Mechanisms of Recognition Memory

    ERIC Educational Resources Information Center

    Odegard, Timothy N.; Koen, Joshua D.; Gama, Jorge M.

    2008-01-01

    A surge of research has been conducted to examine memory editing mechanisms that help distinguish accurate from inaccurate memories. In the present experiment, the authors examined the ability of participants to use novelty detection, recollection rejection, and plausibility judgments to reject lures presented on a recognition memory test.…

  2. A Mechanism for Transition of Concrete to Abstract Cognitive Processes

    ERIC Educational Resources Information Center

    Melnick, Gerald I.

    1973-01-01

    An extension of discrimination-learning theory based on the inhibition of stimulus intensity was proposed and supported as a mechanism of cognitive development. Among 48 normal and 37 educable mentally retarded children the predominant category of transistional children conserved at a low level of stimulus intensity but failed to conserve at a…

  3. Evaluating the Learning Process of Mechanical CAD Students

    ERIC Educational Resources Information Center

    Hamade, R. F.; Artail, H. A.; Jaber, M. Y.

    2007-01-01

    There is little theoretical or experimental research on how beginner-level trainees learn CAD skills in formal training sessions. This work presents findings on how trainees develop their skills in utilizing a solid mechanical CAD tool (Pro/Engineer version 2000i[squared] and later version Wildfire). Exercises at the beginner and intermediate…

  4. Long-Term Adaptation Mechanisms for Fine-Tuning of Man-Made Sensory Processing Systems

    E-print Network

    Harris, John G.

    of processing. Though the pur- pose of these biological adaptation mechanisms is not clear, some theories of such biologically inspired adaptation mechanisms for such engineering prob- lems as offset/gain correctionof IR examples of such biologically inspired adaptation mechanisms for such engineering problems as offset

  5. Mechanical signature analysis using time-frequency signal processing: application to internal combustion engine knock detection

    Microsoft Academic Search

    B. Samimy; G. Rizzoni

    1996-01-01

    Signature analysis consists of the extraction of information from measured signal patterns. The work presented in this paper illustrates the use of time-frequency (TF) analysis methods for the purpose of mechanical signature analysis. Mechanical signature analysis is a mature and developed field; however, TF analysis methods are relatively new to the field of mechanical signal processing, having mostly been developed

  6. Nano-structured vanadium: processing and mechanical properties under quasi-static and dynamic compression

    E-print Network

    Wei, Qiuming

    Nano-structured vanadium: processing and mechanical properties under quasi-static and dynamic form 16 September 2003; accepted 9 October 2003 Abstract We have processed fully dense, nano that the grain size of the consolidated V is around 100 nm. Mechanical properties of the nano-structured V were

  7. Mini ion trap mass spectrometer

    DOEpatents

    Dietrich, Daniel D. (Livermore, CA); Keville, Robert F. (Valley Springs, CA)

    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.

  8. 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.

  9. Expressiveness of Recursion, Replication and Scope Mechanisms in Process Calculi

    E-print Network

    Palamidessi, Catuscia

    Palamidessi INRIA Futurs and LIX, Ã?cole Polytechnique catuscia@lix.polytechnique.fr Frank D. Valencia CNRS and LIX, Ã?cole Polytechnique fvalenci@lix.polytechnnique.fr Process calculi such as CCS [Mil89

  10. Restoration Mechanisms During the Friction Stir Processing of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Nadammal, Naresh; Kailas, Satish V.; Szpunar, Jerzy; Suwas, Satyam

    2015-07-01

    In the current study, correlation of microstructure evolution with bulk crystallographic texture formation during friction stir processing (FSP) of commercial aluminum alloys has been attempted. Electron back-scattered diffraction and X-ray diffraction techniques were employed for characterizing the nugget zone of optimum friction stir processed samples. Volume fraction of measured texture components revealed that the texture formation in aluminum alloys is similar irrespective of the alloy composition. Recrystallization behavior during FSP was more of a composition dependent phenomenon.

  11. Neutrophil extracellular traps sequester circulating tumor cells and promote metastasis

    PubMed Central

    Cools-Lartigue, Jonathan; Spicer, Jonathan; McDonald, Braedon; Gowing, Stephen; Chow, Simon; Giannias, Betty; Bourdeau, France; Kubes, Paul; Ferri, Lorenzo

    2013-01-01

    The majority of patients with cancer undergo at least one surgical procedure as part of their treatment. Severe postsurgical infection is associated with adverse oncologic outcomes; however, the mechanisms underlying this phenomenon are unclear. Emerging evidence suggests that neutrophils, which function as the first line of defense during infections, facilitate cancer progression. Neutrophil extracellular traps (NETs) are extracellular neutrophil-derived DNA webs released in response to inflammatory cues that trap and kill invading pathogens. The role of NETs in cancer progression is entirely unknown. We report that circulating tumor cells become trapped within NETs in vitro under static and dynamic conditions. In a murine model of infection using cecal ligation and puncture, we demonstrated microvascular NET deposition and consequent trapping of circulating lung carcinoma cells within DNA webs. NET trapping was associated with increased formation of hepatic micrometastases at 48 hours and gross metastatic disease burden at 2 weeks following tumor cell injection. These effects were abrogated by NET inhibition with DNAse or a neutrophil elastase inhibitor. These findings implicate NETs in the process of cancer metastasis in the context of systemic infection and identify NETs as potential therapeutic targets. PMID:23863628

  12. Nonactive, prototype mechanical handling system for testing simulated pyrochemical processes

    SciTech Connect

    Harrison, P.S. [Atomic Weapons Establishment, Aldermaston (United Kingdom)

    1990-11-01

    The Chemical Engineering Section at Atomic Weapons Establishments at Aldermaston is responsible for the design of equipment to meet the plutonium recycle flow sheet based on pyrochemical operations. A new design of pyrochemical furnace incorporating programmable remote handling equipment is being developed. To minimize maintenance operation, the handling equipment is based on simple modular units designed for ease of replacement. The paper describes the aim of the program and reviews the progress, over the last twelve months, of design and testing of the nonactive prototype pyrochemical development facility. The facility consists of a glovebox envelope containing a furnace well, a crucible hoist, and a process hoist head, to which, interchangeable process equipment can be fixed. An operator places the crucible of reactants under the crucible hoist and presses a button to initiate the process. All further movements and processing operations are carried out automatically, until the crucible is returned to the starting point. In the new active facility a computer will be connected to seventeen glovebox Programmable Logic Controller (PLC) units. The computer will store the process programs for down-loading to each glovebox, display the status of each station, archive data from each process run and aid fault finding in the PLCs.

  13. Apparatus and process for mechanical power production by acetylene combustion

    Microsoft Academic Search

    1976-01-01

    The design is given of a combustion engine having a combustion zone for burning acetylene with an oxygen-containing gas to produce mechanical power and exhaust gases including HâO and oxides of carbon. A reaction zone contains a compound selected from the group consisting of sodium peroxide, potassium peroxide, lithium peroxide, sodium superoxide, potassium superoxide and lithium superoxide for reacting HâO

  14. Processing of aluminium alloys containing titanium addition by mechanical alloying

    Microsoft Academic Search

    K. R. Cardoso; C. A. D. Rodrigues; W. J. Botta F

    2004-01-01

    In this work, mechanical alloying was used to produce precursor powders of 2024 and 7050 aluminium alloys containing titanium addition. Milling was performed in a planetary mill using a ball to powder weight ratio of 20:1 and a milling time varying from 10 to 100h. Characterisation of the milled powders was performed by X-ray diffraction (XRD), differential scanning calorimetry (DSC)

  15. Combustion Synthesis of Nanocomposite Powders Using A Mechanically Activated Process

    Microsoft Academic Search

    Tatiana L. Talako; Andrei I. Letsko; Tatiana Ph. Grigorieva

    2010-01-01

    The authors investigated aspects of nanocomposite structure formation in Fe + Al + Fe2O3 and Fe + Al + Cr2O3 powder mixtures during combustion synthesis using precursors formed as a result of mechanochemical interaction at the stage of preliminary mechanical activation of reactive mixtures. Despite the significant difference in thermal effects, two types of reactions (aluminothermic reduction of oxides and formation of intermetallics from elements, though in the

  16. Thermo-mechanical phenomena in high speed continuous casting processes

    NASA Astrophysics Data System (ADS)

    Park, Joong Kil

    Thermo-mechanical phenomena during continuous thin slab casting have been studied with the objectives of understanding the mechanism of mold crack formation, and the effect of mold design upon the mechanical behavior of the stand. To achieve these goals, several finite element models have been developed in conjunction with a series of industrial plant trials. First, an investigation of mold crack formation in thin slab casting was undertaken to elucidate the mechanism by which cracks develop and to evaluate possible solutions to the problem. Three-dimensional finite-element thermal-stress models were developed to predict temperature, distortion, and residual stress in thin-slab casting molds, comparing funnel-shaped to parallel molds. Mold wall temperatures were obtained from POSCO in Korea and analyzed to determine the corresponding heat-flux profiles in thin-slab molds. This data was utilized in an elastic-visco-plastic analysis to investigate the deformation of the molds in service for the two different mold shapes. The results of a metallurgical investigation of mold samples containing cracks were used together with the results of the mathematical models, to determine mechanisms and to suggest solutions for the formation of mold cracks. Large cyclic inelastic strains were found in the funnel transition region just below the meniscus, due to the slightly higher temperature at that location. The cracks appear to have propagated by thermal fatigue caused by major level fluctuations. Next, two-dimensional thermo-elastic-visco-plastic analysis was performed for a horizontal slice of the solidifying strand, which moves vertically down the mold during casting. The model calculates the temperature distributions, the stresses and the strains in the solidifying shell, and the air gap between the casting mold and the solidifying strand. Model predictions were verified with an analytical solution and plant trials that were carried out during billet casting at POSCO. The validated model from the billet study was next applied to thin slab casting, using mold temperature and distortion data from the mold cracking study. An investigation of the effect of mold taper on the shrinkage of the solidifying shell, its gap formation, and stress evolution was carved out for different thin slab mold geometries. The model predicts that the shell in funnel molds develops a tensile stress at the slab surface in the funnel transition region due to funnel retraction. This model also suggests that as the funnel depth increases, the possibility of surface cracks at the funnel outside bed position increases.

  17. The investigation of structure, chemical composition, hydrogen isotope trapping and release processes in deposition layers on surfaces exposed to DIII-D divertor plasma

    SciTech Connect

    Buzhinskij, O.I.; Opimach, I.V.; Barsuk, V.A. [TRINITI, Troitsk (Russian Federation); Arkhipov, I.I. [Russian Academy of Science, Moscow (Russian Federation). Inst. of Physical Chemistry; West, W.P.; Wong, C.P.C. [General Atomics, San Diego, CA (United States); Whyte, D. [Univ. of California, San Diego, CA (United States); Wampler, W.R. [Sandia National Labs., Albuquerque, NM (United States)

    1998-05-01

    The exposure of ATG graphite sample to DIII-D divertor plasma was provided by the DiMES (Divertor Material Evaluation System) mechanism. The graphite sample arranged to receive the parallel heat flux on a small region of the surface was exposed to 600ms of outer strike point plasma. The sample was constructed to collect the eroded material directed downward into a trapping zone onto s Si disk collector. The average heat flux onto the graphite sample during the exposure was about 200W/cm{sup 2}, and the parallel heat flux was about 10 KW/cm{sup 2}. After the exposure the graphite sample and Si collector disk were analyzed using SEM, NRA, RBS, Auger spectroscopy. IR and Raman spectroscopy. The thermal desorption was studied also. The deposited coating on graphite sample is amorphous carbon layer. Just upstream of the high heat flux zone the redeposition layer has a globular structure. The deposition layer on Si disk is composed also from carbon but has a diamond-like structure. The areal density of C and D in the deposited layer on Si disk varied in poloidal and toroidal directions. The maximum D/C areal density ratio is about 0.23, maximum carbon density is about 3.8 {times} 10{sup 18}cm{sup {minus}2}, maximum D area density is about 3 {times} 10{sup 17}cm{sup 2}. The thermal desorption spectrum had a peak at 1,250K.

  18. Fused-ring derivatives of quinoxalines: spectroscopic characterization and photoinduced processes investigated by EPR spin trapping technique.

    PubMed

    Barbieriková, Zuzana; Dvoranová, Dana; Bella, Maroš; Milata, Viktor; Czímerová, Adriana; Brezová, Vlasta

    2014-01-01

    10-Ethyl-7-oxo-7,10-dihydropyrido[2,3-f]quinoxaline derivatives, synthesized as promising biologically/photobiologically active compounds were characterized by UV/vis, FT-IR and fluorescent spectroscopy. Photoinduced processes of these derivatives were studied by EPR spectroscopy, monitoring in situ the generation of reactive intermediates upon UVA (?max=365 nm) irradiation. The formation of reactive oxygen species and further oxygen- and carbon-centered radical intermediates was detected and possible reaction routes were suggested. To quantify the investigated processes, the quantum yields of the superoxide radical anion spin-adduct and 4-oxo-2,2,6,6-tetramethylpiperidine N-oxyl generation were determined, reflecting the activation of molecular oxygen by the excited state of the quinoxaline derivative. PMID:25120058

  19. 3-D Modelling of Electromagnetic, Thermal, Mechanical and Metallurgical Couplings in Metal Forming Processes

    SciTech Connect

    Chenot, Jean-Loup; Bay, Francois [Center for Material Forming (CEMEF), Ecole des Mines de Paris - UMR CNRS 7635, BP 207, F-06904 Sophia-Antipolis Cedex (France)

    2007-04-07

    The different stages of metal forming processes often involve - beyond the mechanical deformations processes - other physical coupled problems, such as heat transfer, electromagnetism or metallurgy. The purpose of this paper is to focus on problems involving electromagnetic couplings. After a brief recall on electromagnetic modeling, we shall then focus on induction heating processes and present some results regarding heat transfer, as well as mechanical couplings. A case showing coupling for metallurgic microstructure evolution will conclude this paper.

  20. Process view of reflection mechanism for reuse software architecture

    Microsoft Academic Search

    Zaoqing Liang; Shi Ying; Dan Xie; Xiangyang Jia

    2007-01-01

    Reflection mechanism for reuse software architecture (RMRSA) divides a software architecture into base-level architecture\\u000a and meta-level architecture logically. Base-level architecture is the ordinary architecture; meta-level represents and manipulates\\u000a the reusable meta-information of base-level architecture explicitly. Through reflection, the modification of meta-level architecture\\u000a will result in the modification of the architecture in base-level. Then we can gain a new base-level architecture

  1. Determinants and mechanisms of attentional modulation of neural processing

    Microsoft Academic Search

    Ashesh D. Mehta; John J. Foxe

    2001-01-01

    1.Abstract 2. Overview 3. AttentionPar adigms and their Ecological Validity 3.1. Visuospatial (non-foveal)Attention 3.2. Nonspatial Visual Attention 4. Effects of Attention on BrainActivity Measurements 4.1. Visuo-spatial attention 4.2. Nonspatial Attention 5. Ananatomica,lhierarch y ofattention effects? 6. A temporal hierarchy ofattention effects? 7. BrainMechan isms ofAttention al Modulation 7.1. Neuronal circuits 7.2. Physiology 8. Linkage Between Neural Effects and the Cognitive

  2. Electrical, chemical and mechanical processes in water treeing

    Microsoft Academic Search

    Jean-Pierre Crine

    1998-01-01

    Water treeing is a complex phenomenon involving several processes with many synergistic effects. Although a huge number of papers on the subject have been published over the last 25 years, there is no comprehensive theory able to describe the often contradictory experimental results. However, there are some tendencies that are always observed, whatever the experimental conditions. A critical review of

  3. Cell Separation Processes in Plants—Models, Mechanisms and Manipulation

    Microsoft Academic Search

    Jeremy A. Roberts; Catherine A. Whitelaw; Zinnia H. Gonzalez-Carranza; Michael T. McManus

    2000-01-01

    Abscission and dehiscence are developmental processes that involve the co-ordinated breakdown of the cell wall matrix at discrete sites and at specific stages during the life cycle of a plant. In this review we examine the events that influence the differentiation of abscission and dehiscence zone cells and the changes that are associated with wall degradation. There is convincing evidence

  4. Replisome mechanics: lagging strand events that influence speed and processivity

    PubMed Central

    Georgescu, Roxana E.; Yao, Nina; Indiani, Chiara; Yurieva, Olga; O'Donnell, Mike E.

    2014-01-01

    The antiparallel structure of DNA requires lagging strand synthesis to proceed in the opposite direction of the replication fork. This imposes unique events that occur only on the lagging strand, such as primase binding to DnaB helicase, RNA synthesis, and SS B antigen (SSB) displacement during Okazaki fragment extension. Single-molecule and ensemble techniques are combined to examine the effect of lagging strand events on the Escherichia coli replisome rate and processivity. We find that primase activity lowers replisome processivity but only when lagging strand extension is inoperative. rNTPs also lower replisome processivity. However, the negative effects of primase and rNTPs on processivity are overcome by the extra grip on DNA provided by the lagging strand polymerases. Visualization of single molecules reveals that SSB accumulates at forks and may wrap extensive amounts of single-strand DNA. Interestingly SSB has an inter-strand positive effect on the rate of the leading strand based in its interaction with the replicase ?-subunit. Further, the lagging strand polymerase is faster than leading strand synthesis, indicating that replisome rate is limited by the helicase. Overall, lagging strand events that impart negative effects on the replisome are counterbalanced by the positive effects of SSB and additional sliding clamps during Okazaki fragment extension. PMID:24829446

  5. A study on irregular growing defect mechanism and removal process

    NASA Astrophysics Data System (ADS)

    Lee, Hyemi; Jun, JeaYoung; Jeong, GooMin; Kim, SangChul; Kim, SangPyo; Kim, ChangReol

    2011-11-01

    Main Topics of a photomask have been CD(Critical Dimension), Overlay and Defects. In side of defects, technique suppressing growing defects which are occurring on a mask surface becomes as important as defect control method during mask manufacturing process. Conventional growing defects arise out of combination of sulfuric ion on a mask surface and environmental facts such as pellicle ingredient, humidity and etc. So Mask cleaning process was driven to reduce sulfuric acid on a mask surface which source of growing defects. And actually various cleaning process has been developed through the elimination of sulfuric acid such as DI, O3 cleaning. Normally Conventional growing defects are removed using DI, SC1 or SPM cleaning according to incidence. But recently irregular growing defects are occurred which are completely distinct from conventional growing defects. Interestingly, irregular growing defects are distributed differently from conventional on a mask. They spread in isolated space patterns and reduce the transmittance so that space pattern size continuously decreased. It causes Wafer Yield loss. Furthermore, irregular growing defects are not fully removed by cleaning which is traditional removal process. In this study, we provide difference between conventional and irregular growing defects based on its characteristic and distributed formation. In addition, we present and discuss removal and control technique about irregular growing defects. For elemental analysis and study, diverse analysis tool was applied such as TEM for checking Cross-Section, AFM for checking the roughness of surface, EDAX, AES, IC for analyzing remained ions and particles on the mask and AIMS.

  6. A mechanized process algebra for verification of device synchronization protocols

    NASA Technical Reports Server (NTRS)

    Schubert, E. Thomas

    1992-01-01

    We describe the formalization of a process algebra based on CCS within the Higher Order Logic (HOL) theorem-proving system. The representation of four types of device interactions and a correctness proof of the communication between a microprocessor and MMU is presented.

  7. Knowledge Discovery Process for Characterization of Materials Failure Mechanism

    NASA Technical Reports Server (NTRS)

    Cios, Krzysztof J.

    1999-01-01

    It is the intent of this project to provide a platform to visualize the various data collected from stress-strain testing of composite ceramic matrix materials. The data collected from the stress-strain tests are acoustic emissions (AE). As a material is subjected to a stress-strain test, various failure mechanisms occur in the material. The recorded sounds emitted during the test may correspond to various failure mechanisms. This project, thus, will give a possible way to visualize the data and data derived from the recorded AE. The stress-strain testing was performed on several composite matrix material combinations. Each of these tests produced anywhere from 1000 to 10,000+ AE events. For each AE event recorded, several characteristics in both the time and frequency domains are created. This project has two goals. First, this project will provide a summation page for a selected waveform. This page will include all of the characteristics determined from the AE event waveform along with graphs of the AE event waveform and its corresponding Power Spectrum. The other function of this project is to retrieve and display selected AE event waveforms for comparison.

  8. Controlled collisions for multi-particle entanglement of optically trapped atoms

    Microsoft Academic Search

    Olaf Mandel; Markus Greiner; Artur Widera; Tim Rom; Theodor W. Hänsch; Immanuel Bloch

    2003-01-01

    Entanglement lies at the heart of quantum mechanics, and in recent years has been identified as an essential resource for quantum information processing and computation. The experimentally challenging production of highly entangled multi-particle states is therefore important for investigating both fundamental physics and practical applications. Here we report the creation of highly entangled states of neutral atoms trapped in the

  9. Ultracold atomic collisions in tight harmonic traps: Perturbation theory, ionization losses and application to metastable helium atoms

    E-print Network

    Beams, T J; Whittingham, I B

    2004-01-01

    Collisions between tightly confined atoms can lead to ionization and hence to loss of atoms from the trap. We develop second-order perturbation theory for a tensorial perturbation of a spherically symmetric system and the theory is then applied to processes mediated by the spin-dipole interaction. Redistribution and loss mechanisms are studied for the case of spin-polarized metastable helium atoms and results obtained for the five lowest s states in the trap and trapping frequencies ranging from 1 kHz to 10 MHz.

  10. Trap characterization of silicon nitride thin films by a modified trap spectroscopy technique

    NASA Astrophysics Data System (ADS)

    Midya, Kousik; Dhar, Subhabrata; Kottantharayil, Anil

    2013-10-01

    Energy levels of traps in silicon nitride are determined using a modified trap spectroscopy method, based on filling of traps using electrical stress followed by optical detrapping, in a metal-silicon nitride-silicon structure. Indium tin oxide with 84% transmittance is used as transparent electrode. Photon energy dependent shift in the flat band voltage is used to estimate type and energetic position of the traps. Here, we report detection of two prominent hole trap levels at 0.5 and 1.1 eV above the valance band edge. The study suggests that phonons hardly participate in the detrapping process of holes in Si3N4.

  11. Sisyphus Cooling of Electrically Trapped Polyatomic Molecules

    E-print Network

    M. Zeppenfeld; B. G. U. Englert; R. Glöckner; A. Prehn; M. Mielenz; C. Sommer; L. D. van Buuren; M. Motsch; G. Rempe

    2012-07-31

    The rich internal structure and long-range dipole-dipole interactions establish polar molecules as unique instruments for quantum-controlled applications and fundamental investigations. Their potential fully unfolds at ultracold temperatures, where a plethora of effects is predicted in many-body physics, quantum information science, ultracold chemistry, and physics beyond the standard model. These objectives have inspired the development of a wide range of methods to produce cold molecular ensembles. However, cooling polyatomic molecules to ultracold temperatures has until now seemed intractable. Here we report on the experimental realization of opto-electrical cooling, a paradigm-changing cooling and accumulation method for polar molecules. Its key attribute is the removal of a large fraction of a molecule's kinetic energy in each step of the cooling cycle via a Sisyphus effect, allowing cooling with only few dissipative decay processes. We demonstrate its potential by reducing the temperature of about 10^6 trapped CH_3F molecules by a factor of 13.5, with the phase-space density increased by a factor of 29 or a factor of 70 discounting trap losses. In contrast to other cooling mechanisms, our scheme proceeds in a trap, cools in all three dimensions, and works for a large variety of polar molecules. With no fundamental temperature limit anticipated down to the photon-recoil temperature in the nanokelvin range, our method eliminates the primary hurdle in producing ultracold polyatomic molecules. The low temperatures, large molecule numbers and long trapping times up to 27 s will allow an interaction-dominated regime to be attained, enabling collision studies and investigation of evaporative cooling toward a BEC of polyatomic molecules.

  12. Effect of pore structure on gas trapping in porous media

    NASA Astrophysics Data System (ADS)

    Mohammadian, Sadjad; Geistlinger, Helmut; Vogel, Hans-Jörg

    2014-05-01

    Capillary trapping of nonwetting phase in porous media plays an important role in many geological processes. For example, large portions of hydrocarbons cannot be extracted from reservoirs due to capillary forces, while in carbon sequestration processes; capillary trapping might improve the storage efficiency. An important case is when the wetting phase (mostly water) displaces a low-viscosity low-density fluid. In such cases, like water encroachment into gas reservoirs or rising of water table in soils, competition of gravity, viscous, and capillary forces determines the final configuration of the fluids in invaded zone. The trapped nonwetting phase and its distribution within the porous media will affect many other processes such as flow of the other fluids and mass transfer phenomena. Thus, investigating the parameters affecting phase trapping and distribution, especially their relation to pore structure, which controls the capillary action, is required. The aim is to predict gas trapping from structural properties of the material. We conducted a series of column experiments, in which water displaces air at a range of flow rates in different glass-bead packs. The final 3D configuration and morphology of fluids was observed using X-Ray Computed Tomography (CT). We extracted 3D structure of porous media as well as of the trapped gas phase, and quantified them in terms of volume ratios, interfacial area, and morphology. Then we investigated the relations of the trapped phase to capillary forces (pore structure) and viscous forces (front velocity). The results give us new insights to explore the flow and dissolution processes: We found no systematic dependency of the front velocity of the invading water phase in the velocity range from 0.1 to 0.6 cm/min what corresponds to capillary numbers from 2 to 12 ×10^-6. Our experimental results indicate that the capillary trapping mechanism is controlled by the local pore structure and local connectivity and not by thermodynamics, i.e. large pores are occupied first by the gas phase.

  13. Flexible aerogel composite for mechanical stability and process of fabrication

    DOEpatents

    Coronado, Paul R. (Livermore, CA); Poco, John F. (Livermore, CA)

    1999-01-01

    A flexible aerogel and process of fabrication. An aerogel solution is mixed with fibers in a mold and allowed to gel. The gel is then processed by supercritical extraction, or by air drying, to produce a flexible aerogel formed to the shape of the mold. The flexible aerogel has excellent thermal and acoustic properties, and can be utilized in numerous applications, such as for energy absorption, insulation (temperature and acoustic), to meet the contours of aircraft shapes, and where space is limited since an inch of aerogel is a 4-5 times better insulator than an inch of fiberglass. The flexible aerogel may be of an inorganic (silica) type or an organic (carbon) type, but containing fibers, such as glass or carbon fibers.

  14. Flexible aerogel composite for mechanical stability and process of fabrication

    DOEpatents

    Coronado, Paul R. (Livermore, CA); Poco, John F. (Livermore, CA)

    2000-01-01

    A flexible aerogel and process of fabrication. An aerogel solution is mixed with fibers in a mold and allowed to gel. The gel is then processed by supercritical extraction, or by air drying, to produce a flexible aerogel formed to the shape of the mold. The flexible aerogel has excellent thermal and acoustic properties, and can be utilized in numerous applications, such as for energy absorption, insulation (temperature and acoustic), to meet the contours of aircraft shapes, and where space is limited since an inch of aerogel is a 4-5 times better insulator than an inch of fiberglass. The flexible aerogel may be of an inorganic (silica) type or an organic (carbon) type, but containing fibers, such as glass or carbon fibers.

  15. Modeling of Processing Path of Ti During Mechanical Deformation

    E-print Network

    Garmestani, Hamid

    in Titanium ­ hexagonal ( phase) ­ cubic ( phase) · Conclusion #12;3 Representation of Texture ODF is defined )()(),( l lM m lN n mn l mn l gTFgf &&& rlFe l e lM v ll v l + = = 0 12 1 )( 1 µµ #12;4 Microstructure propertiesX #12;5 Question: How to find the processing path from initial microstructure of the raw material

  16. Improving Tools and Processes in Mechanical Design Collaboration

    NASA Technical Reports Server (NTRS)

    Briggs, Clark

    2009-01-01

    Cooperative product development projects in the aerospace and defense industry are held hostage to high cost and risk due to poor alignment of collaborative design tools and processes. This impasse can be broken if companies will jointly develop implementation approaches and practices in support of high value working arrangements. The current tools can be used to better advantage in many situations and there is reason for optimism that tool vendors will provide significant support.

  17. Fractural process and toughening mechanism of laminated ceramic composites

    Microsoft Academic Search

    Zhang Yafang; Tang Chun'an; Zhang Yongbin; Liang Zhenzao

    2007-01-01

    Based on the model of multi-layer beam and the assumption of micro-inhomogeneity of material, the 3D fractural characteristics of laminated ceramic composites have been studied with numerical simulation. Under three-point bending load, crack initiation, coalescence, propagation, tuning off in the weak interface and final rupture have been simulated. The spatial distribution and evolution process of acoustic emission are also presented

  18. A review of OSHA PSM citations relating to mechanical integrity of process piping

    SciTech Connect

    Casada, M.L.; Remson, A.C.; Yerger, C.M. [JBF Associates, Inc., Knoxville, TN (United States)

    1996-07-01

    OSHA`s process safety management (PSM) regulation has been in effect for more than three years. The regulation poses challenges for facilities in documenting the integrity of process piping systems. This paper summarizes the results of a project sponsored by the Materials Technology Institute (MTI) to compile PSM enforcement information relating to mechanical integrity W and process safety information (PSI) relating to equipment. This paper provides an analysis of how OSHA is citing violations of the PSM regulation as it relates to process piping. This information should be helpful to engineers and maintenance personnel who need guidance on how to ``OSHA-proof`` their mechanical integrity compliance for process piping systems.

  19. Mechanism of silk processing in insects and spiders

    NASA Astrophysics Data System (ADS)

    Jin, Hyoung-Joon; Kaplan, David L.

    2003-08-01

    Silk spinning by insects and spiders leads to the formation of fibres that exhibit high strength and toughness. The lack of understanding of the protein processing in silk glands has prevented the recapitulation of these properties in vitro from reconstituted or genetically engineered silks. Here we report the identification of emulsion formation and micellar structures from aqueous solutions of reconstituted silkworm silk fibroin as a first step in the process to control water and protein-protein interactions. The sizes (100-200nm diameter) of these structures could be predicted from hydrophobicity plots of silk protein primary sequence. These micelles subsequently aggregated into larger `globules' and gel-like states as the concentration of silk fibroin increased, while maintaining solubility owing to the hydrophilic regions of the protein interspersed among the larger hydrophobic regions. Upon physical shearing or stretching structural transitions, increased birefringence and morphological alignment were demonstrated, indicating that this process mimics the behaviour of similar native silk proteins in vivo. Final morphological features of these silk materials are similar to those observed in native silkworm fibres.

  20. When norms are violated: imagined interactions as processing and coping mechanisms

    Microsoft Academic Search

    Kristen M. Berkos; Terre H. Allen; Patricia Kearney; Timothy G. Plax

    2001-01-01

    Relying on the fundamental assumption of violation theories that norm violations stimulate receiver thought processes, we explored receivers' symbolic cognitive processes in response to particular types of norm violations. Specifically, we reasoned that imagined interactions serve as a processing mechanism whereby individuals review the behavior of another, identify the type of norm violation, and make decisions about how to respond-all

  1. High Temp. Material Processes 4 (2000) 253-290 253 Dimensional characteristics and mechanical properties of

    E-print Network

    Yao, Y. Lawrence

    2000-01-01

    High Temp. Material Processes 4 (2000) 253-290 253 Dimensional characteristics and mechanical, as well as for adjusting #12;HIGH TEMP. MATERIAL PROCESSES 254 and aligning sheet metal components (Magee, et al., 1994). #12;HIGH TEMP. MATERIAL PROCESSES 255 Despite of the progress made to date

  2. Hydro-Mechanical Loading and Compressibility of Fibrous Media for Resin Infusion Processes

    E-print Network

    Paris-Sud XI, Université de

    . For this reason, Liquid Composite Molding (LCM) processes are widely used. These processes consist of injecting1 Hydro-Mechanical Loading and Compressibility of Fibrous Media for Resin Infusion Processes P investigating the compressibility behaviour of composite preform with a view of modelling resin infusion

  3. Quantum Mechanics and Perceptive Processes: A Reply to Elio Conte

    NASA Astrophysics Data System (ADS)

    Ghirardi, GianCarlo

    2014-11-01

    Recently, Elio Conte has commented a paper by the present author devoted to analyze the possibility of checking experimentally whether the perceptual process can lead to the collapse of the wavefunction. Here we answer to the comments by Conte and we show that he has missed to grasp the crucial elements of our proposal. Morever, we discuss some ideas put forward by Conte concerning the occurrence of quantum superpositions of different states of consciousness and we show that they are rather vague and not cogent.

  4. Quantum Mechanics and Perceptive Processes: A Reply to Elio Conte

    NASA Astrophysics Data System (ADS)

    Ghirardi, GianCarlo

    2015-07-01

    Recently, Elio Conte has commented a paper by the present author devoted to analyze the possibility of checking experimentally whether the perceptual process can lead to the collapse of the wavefunction. Here we answer to the comments by Conte and we show that he has missed to grasp the crucial elements of our proposal. Morever, we discuss some ideas put forward by Conte concerning the occurrence of quantum superpositions of different states of consciousness and we show that they are rather vague and not cogent.

  5. Psychotherapy: process, mechanisms, and science-practice integration.

    PubMed

    Boswell, James F

    2015-03-01

    I received the Early Career Award from Division 29 and the American Psychological Foundation in 2013. In this article, I briefly review some of my research areas, relevant issues, and future directions. Specifically, I focus on 3 core research areas: psychotherapy process-outcome, psychotherapy integration, and science-practice integration. Within each of these core areas, I also touch on important methodological issues. In addition, I argue that progress in the field will require the application of diverse research methods, spanning basic and applied areas, as well as interdisciplinary and interinstitutional collaboration. PMID:25602180

  6. Theoretical Study of the Inverting Mechanism in a Processive Cellobiohydrolase with Quantum Mechanical Calculations

    SciTech Connect

    Kim, S.; Payne, C. M.; Himmel, M. E.; Crowley, M. F.; Paton, R. S.; Beckham, G. T.

    2012-01-01

    The Hypocrea jecorina Family 6 cellobiohydrolase (Cel6A) is one of most efficient enzymes for cellulose deconstruction to soluble sugars and is thus of significant current interest for the growing biofuels industry. Cel6A is known to hydrolyze b(1,4)-glycosidic linkages in cellulose via an inverting mechanism, but there are still questions that remain regarding the role of water and the catalytic base. Here we study the inverting, single displacement, hydrolytic reaction mechanism in Cel6A using density functional theory (DFT) calculations. The computational model used to follow the reaction is a truncated active site model with several explicit waters based on structural studies of H. jecorina Cel6A. Proposed mechanisms are evaluated with several density functionals. From our calculations, the role of the water in nucleophilic attack on the anomeric carbon, and the roles of several residues in the active site loops are elucidated explicitly for the first time. We also apply quantum mechanical calculations to understand the proton transfer reaction which completes the catalytic cycle.

  7. Quantification of capillary trapping of gas clusters using X-ray microtomography

    NASA Astrophysics Data System (ADS)

    Geistlinger, Helmut; Mohammadian, Sadjad; Schlueter, Steffen; Vogel, Hans-Joerg

    2014-05-01

    A major difficulty in modeling multiphase flow in porous media is the emergence of trapped phases. Our experiments demonstrate that gas can be trapped in either single-pores, multipores, or in large connected networks. These large connected clusters can comprise up to eight grain volumes and can contain up to 50% of the whole trapped gas volume. About 85% of the gas volume is trapped by multipore gas clusters. This variety of possible trapped gas clusters of different shape and volume will lead to a better process understanding of bubble-mediated mass transfer. Since multipore gas bubbles are in contact with the solid surface through ultrathin adsorbed water films the interfacial area between trapped gas clusters and intergranular capillary water is only about 80% of the total gas surface. We could derive a significant (R2 = 0.98) linear relationship between the gas-water-interface and gas saturation. We found no systematic dependency of the front velocity of the invading water phase in the velocity range from 0.1 to 0.6 cm/min corresponding to capillary numbers from 2 × 10-7 to 10-6. Our experimental results indicate that the capillary trapping mechanism is controlled by the local pore structure and local connectivity and not by thermodynamics, i.e., by the minimum of the Free Energy, at least in the considered velocity range. Consistent with this physical picture is our finding that the trapping frequency (= bubble-size distribution) reflects the pore size distribution for the whole range of pore radii, i.e., the capillary trapping process is determined by statistics and not by thermodynamics.

  8. Processing and mechanical behavior of hypereutectoid steel wires

    SciTech Connect

    Lesuer, D.R.; Syn, C.K.; Sherby, O.D.; Kim, D.K.

    1996-06-25

    Hypereutectoid steels have the potential for dramatically increasing the strength of wire used in tire cord and in other high strength wire applications. The basis for this possible breakthrough is the elimination of a brittle proeutectoid network that can form along grain boundaries if appropriate processing procedures and alloy additions are used. A review is made of work done by Japanese and other researchers on eutectoid and mildly hypereutectoid wires. A linear extrapolation of the tensile strength of fine wires predicts higher strengths at higher carbon contents. The influence of processing, alloy additions and carbon content in optimizing the strength, ductility and fracture behavior of hypereutectoid steels is presented. It is proposed that the tensile strength of pearlitic wires is dictated by the fracture strength of the carbide lamella at grain boundary locations in the carbide. Methods to improve the strength of carbide grain boundaries and to decrease the carbide plate thickness will contribute to enhancing the ultrahigh strength obtainable in hypereutectoid steel wires. 23 refs., 13 figs., 1 tab.

  9. Mechanisms of shark skin suppression by novel polymer processing aids

    NASA Astrophysics Data System (ADS)

    Wagner, M. H.; Himmel, T.; Kulikov, O.; Hornung, K.

    2014-05-01

    The extrusion rate of polyethylene (PE) with narrow molar weight distribution, as e.g. metallocen catalysed polyethylene (m-PE), is limited by melt fracture. The first level of fracture is a surface defect called sharkskin. Common polymer processing aids based on fluorinated polymers shift the onset of sharkskin to higher extrusion rates by creating a "low energy surface" at the die wall and promoting wall slip. Alternatively, Kulikov et al. [1, 2] suggested thermoplastic elastomers (TPE) for sharkskin suppression, and Müller [3] showed the suitability of some TPEs as polymer processing aids. We investigated the slip velocity of several TPEs against steel, and the slip velocity in a polymeric interface between polyethylene (PE) and TPE by rotational plate-plate rheometry in the Newtonian flow regime. TPEs with lower viscosities showed higher slip velocities against steel. However, the interfacial slip velocities between PE and TPE were found to be viscosity independent. In both cases, the slip velocity was found to be proportional to the applied shear stress.

  10. Investigation of material removal mechanism of silicon wafer in the chemical mechanical polishing process using molecular dynamics simulation method

    NASA Astrophysics Data System (ADS)

    Han, Xuesong; Hu, Yuanzhong; Yu, Siyuan

    2009-06-01

    Chemical mechanical polishing (CMP) technology, being the mainstream technique of acquiring global planarization and nanometer level surface, has already become an attractive research item. In the case of CMP process, the indentation depth lies in the range of nanometer or sub-nanometer, huge hydrostatic pressure induced in the local deformation area which makes the material removal and surface generation process different from traditional manufacturing process. In order to investigate the physical essence of CMP technique, the authors carry out molecular dynamics (MD) analysis of chemical mechanical polishing of a silicon wafer. The simulation result shows that huge hydrostatic pressure is induced in the local area and leads to the silicon atom transform from the classical diamond structure ( ? silicon) to metal structure ( ? silicon). This important factor results in the ductile fracture of silicon and then in the acquisition of a super-smooth surface.

  11. Thalamic mechanisms that process a temporal pulse code for pain.

    PubMed

    Emmers, R

    1976-02-27

    The sequential ordering of spikes emitted by single thalamic neurons which respond to noxious stimulation was studied using rats anesthetized with a mixture of alpha-chloralose and urethane. An electrical stimulus applied to the sciatic nerve contralateral to the thalamic recording site fired single thalamic SII neurons with a short latency spike burst and with long latency spikes which occurred at relatively fixed intervals. On repetition of stimulation, the short latency spike burst formed a high amplitude peak on sequential spike density histograms (I of Fig. 2B); the long latency spikes formed peaks of relatively low amplitude (M1, M2, M3 of Fig. 2B). Histograms of touch and light pressure relay neurons found within the thalamic SII differed conspicuously from that of Fig. 2B. Further experiments revealed that the I peak contained frequency coded information about the stimulus intensity, whereas the M peaks with their temporal relationship to the I peak coded information pertaining to a particular sensory modality. The M peaks are formed by timed firing in a positive feedback loop found between the thalamic SII and the nucleus centrum medianum-nucleus parafascicularis (CM-Pf) neurons. Consequently, the M peaks can be abolished without losing the I peak by a lesion placed in a portion of the CM-Pf complex or by the administration or morphine which is able to disorganize the timing mechanism of the feedback loop. Therefore, it is reasonably certain that the modality coded by the M peaks is pain. PMID:1252935

  12. Impact of dopant species on the interfacial trap density and mobility in amorphous In-X-Zn-O solution-processed thin-film transistors

    NASA Astrophysics Data System (ADS)

    Benwadih, Mohammed; Chroboczek, J. A.; Ghibaudo, Gérard; Coppard, Romain; Vuillaume, Dominique

    2014-06-01

    Alloying of In/Zn oxides with various X atoms stabilizes the IXZO structures but generates electron traps in the compounds, degrading the electron mobility, ?. To assess whether the latter is linked to the oxygen affinity or the ionic radius, of the X element, several IXZO samples are synthesized by the sol-gel process, with a large number (14) of X elements. The IXZOs are characterized by XPS, SIMS, DRX, and UV-spectroscopy and used for fabricating thin film transistors. Channel ? and the interface defect density NST, extracted from the TFT electrical characteristics and low frequency noise, followed an increasing trend and the values of ? and NST are linked by an exponential relation. The highest ? (8.5 cm2V-1s-1) is obtained in In-Ga-Zn-O, and slightly lower value for Sb and Sn-doped IXZOs, with NST ? 2 × 1012 eV-1 cm-2, close to that of the In-Zn-O reference TFT. This is explained by a higher electronegativity of Ga, Sb, and Sn than Zn and In, their ionic radius values being close to that of In and Zn. Consequently, Ga, Sb, and Sn induce weaker perturbations of In-O and Zn-O sequences in the sol-gel process, than the X elements having lower electronegativity and different ionic radius. The TFTs with X = Ca, Al, Ni and Cu exhibited the lowest ? and NST > 1013 eV-1cm-2, most likely because of metallic or oxide clusters formation.

  13. Trapping cavitation bubbles with a self-focused laser beam

    Microsoft Academic Search

    Jing Yong Ye; Guoqing Chang; Theodore B. Norris; Christine Tse; Marwa J. Zohdy; Kyle W. Hollman; Matthew O'Donnell; James R. Baker Jr.

    2004-01-01

    We observed that laser-induced cavitation bubbles in water can be trapped in a self-focused laser beam. Both optical imaging and acoustic detection have been utilized to confirm bubble trapping. Transverse and longitudinal trapping forces were measured to be as large as 87 and 11 pN, respectively. This result is contrary to conventional wisdom, since the mechanism of trapping in conventional

  14. Age and sex selectivity in trapping mule deer

    SciTech Connect

    Garrott, R.A.; White, G.C.

    1982-01-01

    A mule deer (Odocoileus hemionus) trapping experiment is described using modified Clover traps in which changes in the placement of bait and height of the trap door modified the ratio of adult does to male and female fawns captured. The mechanisms responsible for the changes in age-sex capture ratios are discussed and indicate that modified Clover traps selectivity capture mule deer, thus introducing bias into population sampling. (JMT)

  15. 3D Modeling of Coupled Rock Deformation and Thermo-Poro-Mechanical Processes in Fractures

    E-print Network

    Rawal, Chakra

    2012-07-16

    Problems involving coupled thermo-poro-chemo-mechanical processes are of great importance in geothermal and petroleum reservoir systems. In particular, economic power production from enhanced geothermal systems, effective water-flooding of petroleum...

  16. Two mechanisms for optic flow and scale change processing of looming

    E-print Network

    Vaina, Lucia M.

    Two mechanisms for optic flow and scale change processing of looming Brain and Vision Research and Vision Research Laboratory, Department of Biomedical Engineering, Boston University, Boston, MA, USAKunjan D. Rana Brain and Vision Research Laboratory, Department of Biomedical Engineering, Boston

  17. Mud volcanism: Processes and implications Mud volcanoes: generalities and proposed mechanisms

    E-print Network

    Manga, Michael

    Editorial Mud volcanism: Processes and implications Mud volcanoes: generalities and proposed mechanisms Mud volcanoes can be large and long lived geological structures that morphologically resemble magmatic volcanoes. Because of their capricious behaviour and their spectacular morphology and landscapes

  18. City of Palmdale This page outlines solar PV incentives, financing mechanisms, permitting process, and

    E-print Network

    City of Palmdale This page outlines solar PV incentives, financing mechanisms, permitting process | Financing | Incentives | Permitting | Interconnection Contact Information City of Palmdale Building programs to fit your needs Apply for rebates and incentives on your behalf Apply for local permits

  19. 3D Modeling of Coupled Rock Deformation and Thermo-Poro-Mechanical Processes in Fractures 

    E-print Network

    Rawal, Chakra

    2012-07-16

    Problems involving coupled thermo-poro-chemo-mechanical processes are of great importance in geothermal and petroleum reservoir systems. In particular, economic power production from enhanced geothermal systems, effective ...

  20. On the mechanisms of cation diffusion processes in ternary feldspars

    NASA Astrophysics Data System (ADS)

    Behrens, H.; Johannes, W.; Schmalzried, H.

    1990-01-01

    Cation diffusion processes have been studied in single crystals of intermediate plagioclase and albite composition by tracer-diffusion experiments and optical absorption spectroscopy. Tracer-diffusivities were determined by the residual activity method, using the radioactive isotopes 22Na, 45Ca and 59Fe. In most cases, diffusion experiments were performed at 1 bar, at controlled oxygen activity and at temperatures between 750 and 1300°C. The obtained Na-diffusivities for plagioclases were much smaller then previously determined for albite. This indicates a strong composition dependence of Na-diffusion. In contrast, Ca-diffusivity in albite does not differ very much from that in intermediate plagioclases. The relative diffusivities determined for plagioclase of composition An62 at 1200° C (CO/CO2 =50?50) were D {infNa/sup*}? D {infFe/sup*}? D {infCa/sup*}=5000?10?1. Despite the an isotropic structure of feldspars, no difference was found for Na-and Ca-diffusion normal to (001) and normal to (010). Water pressure of 2 kbar has no influence on the Na-diffusivity. In contrast to the Ca-diffusion, a dependence on oxyggen activity was found for Na-and Fe-diffusion. Fe-diffusivity increases with decreasing oxygen activity. This can be correlated to changes in oxidation state of iron dissolved in the plagioclases. Optical absorption spectroscopy shows that iron is oxidized in the plagioclases by annealing in air. This effect can be reversed by annealing at reducing conditions. A model is proposed to explain the oxidation of iron by a chemical diffusion process in which A-vacancies are formed by out-diffusion of Na+. Preannealing of samples in air gives a temperature independent decrease of Na-diffusivity by a factor of about 2.5. This effect is explained with help of a simple disorder model for A-cations in ternary feldspars. It is concluded that Na+ diffuses via interstitials and that the A-vacancy concentration in the plagioclases is controlled extrinsically, probably by dissolved SiO2.

  1. Thermoeconomic design of a multi-effect evaporation mechanical vapor compression (MEE–MVC) desalination process

    Microsoft Academic Search

    A. S. Nafey; H. E. S. Fath; A. A. Mabrouk

    2008-01-01

    This work presents thermoeconomic design for a multi-effect evaporation–mechanical vapor compression (MEE–MVC) desalination process. Exergy and thermoeconomic mathematical models of the considered process units are developed and presented in this work. The design data of an existing MEE–MVC (1500 m3\\/day) desalination process is used for the present analysis. The effect of using external steam to initiate the evaporation process is

  2. Processing-Mechanical Property Relationship of Thin Microcellular PET Sheet Prepared by Compression Molding

    Microsoft Academic Search

    Yinglin Li; Rong Guan; Banglong Xiang; Zhaoxin Xiao; Yajing Jiang; Deping Lu

    2008-01-01

    This article presented processing-mechanical property relationship of thin microcellular poly(ethylene terephthlate) (PET) sheet prepared by compression molding. The results showed that the saturation time and the lower-plate temperature had more effects on the mechanical property. The upper-plate temperature and the PET thickness also had some effects on the mechanical property. The upper-plate temperature had more pronounced effect on the specific

  3. Rheology, processing, and mechanical properties of thermoplastic\\/graphite fiber composites

    Microsoft Academic Search

    Scobbo; J. J. Jr

    1989-01-01

    Various cause and effect relations between the rheology, processing and mechanical properties of poly(ether ether ketone) (PEEK) and poly(arylene sulfide) (PAS) matrix composites were studied. The test methods and characterization schemes used emphasize novel techniques for characterizing composites that have not been used previously. A dynamic mechanical analyzer has been modified and used to characterize transition temperatures of the neat

  4. Machining Performance Optimization in End ED Milling and Mechanical Grinding Compound Process

    Microsoft Academic Search

    Renjie Ji; Yonghong Liu; Yanzhen Zhang; Fei Wang; Baoping Cai; Xin Dong

    2012-01-01

    Silicon carbide (SiC) ceramic has been widely used in modern industry for its excellent physical and mechanical properties. However, SiC ceramic is difficult to machine owing to its high hardness and brittleness. This article presents a novel compound process that integrates end electric discharge (ED) milling and mechanical grinding to machine SiC ceramic. The process is able to effectively machine

  5. Machining Performance Optimization in End ED Milling and Mechanical Grinding Compound Process

    Microsoft Academic Search

    Renjie Ji; Yonghong Liu; Yanzhen Zhang; Fei Wang; Baoping Cai; Xin Dong

    2011-01-01

    Silicon carbide (SiC) ceramic has been widely used in modern industry for its excellent physical and mechanical properties. However, SiC ceramic is difficult to machine owing to its high hardness and brittleness. This paper presents a novel compound process that integrates end electric discharge (ED) milling and mechanical grinding to machine SiC ceramic. The process is able to effectively machine

  6. Processing and mechanical behavior of aluminium oxide microstructure composites

    NASA Astrophysics Data System (ADS)

    Pavlacka, Robert J.

    We have proposed a new class of composites that accesses different component properties not through the use of distinct materials, but through the exploitation of the microstructure-property relationship within a single material. That is, we seek to adapt composite concepts to take advantage of the considerable variance in properties associated with different microstructures. This new class of composites is called microstructure composites. Microstructure composites are predominately single phase ceramics that utilize multiple distinct microstructure features in the same composite to obtain unique property combinations. Spatial control and composite connectivity of the individual microstructure components of a microstructure composite are ultimately the key to developing and controlling useful and unique properties. Microstructural features can be controlled via the starting location and transport of the dopants, minority second phases, and liquid phases that are used to manipulate microstructure development. This work focuses on textured-equiaxed microstructure in the Al2O 3 system. Texture is obtained in situ using templated grain growth (TGG). To control microstructure development locally during microstructure composite fabrication, it is important to use relatively low levels of dopant to mitigate the effects of dopant interdiffusion. Therefore, the development of texture in alpha-Al2O3 using TGG was explored under low liquid-phase dopant concentration conditions. High temperature dilatometry was performed to quantify the effect of template constraint on x-y plane shirinkage and the extent to which this constraint could be mitigated as a function of the dopant concentration. x-y plane shrinkage was observed to be increasingly constrained with increasing template loading and decreasing dopant concentration. Final x-y plane shrinkage was greater for samples with 0.14 wt% dopant than for those without dopant, despite have a much lower peak strain rate. It was concluded that densification was impeded by the dopant at lower temperatures but enhanced significantly above 1450°C. Texture is highly developed in samples with no dopant and 0.14 wt% dopant by 1550°C and in samples with 2 wt% dopant by 1350°C. We proposed a new class of composites (called microstructure composites) that accesses different component properties not through the use of distinct materials, but rather through the exploitation of the microstructure-property relationship within a single material. Microstructure composites, therefore, are single phase ceramics that combine components with distinct microstructures within a single composite to obtain unique property combinations. Spatial control and composite connectivity of the individual microstructural 'components' of a microstructure composite are ultimately the key to developing and controlling useful and unique properties. Microstructural components are developed by controlling the starting location and transport of dopants during processing and sintering. This work focuses on alpha-Al2O3 microstructure composites that combine textured components, developed in situ using templated grain growth (TGG), and fine-grained equiaxed components. To control microstructure development locally during composite fabrication, it is important to use relatively low levels of dopant to mitigate the effects of dopant interdiffusion. Therefore, the development of texture in alpha-Al 2O3 using low liquid-phase dopant concentrations was explored, with a focus on the effect of template constraint on texture plane shrinkage. High quality texture was obtained with just 0.14 wt% (SiO2 + CaO) dopant. Textured Al2O3 exhibited transgranular fracture, as well as lower strength and fracture toughness than the fine-grained equiaxed Al2O3. A processing strategy using tape casting was developed for the fabrication of textured-equiaxed Al2O3 microstructure composites with 2-2 connectivity. Dopants used to promote TGG (SiO2 + CaO) were included in the templated tapes and dopants used to prevent abnormal grain growth (MgO) were inclu

  7. Coupled Hydro-mechanical Processes In Rock Salt

    NASA Astrophysics Data System (ADS)

    Popp, T.; Kern, H.; Schulze, O.

    Salt structures are widely used as host rocks for the storage of oil and hydrocarbons and, probably, for the long-term storage of radioactive waste, due to their very low in-situ permeability (less than 10-20 m2). The low permeability is basically attributed to the ductility of the halite minerals ensuring healing processes. Nevertheless, rock salt shows all aspects of brittle-ductile deformation. The poster presents results of deformation experiments focusing on the transport properties of rock salt subjected to a pore fluid pressure. Combined measurements of ultrasonic wave velocities (Vp, Vs) and permeability were used to determine the state of stresses at the dilatancy boundary, that is, at the transition from the compaction to the dilation domain. The crack-sensitivity of ultrasonic wave velocities is found to provide a powerful means to monitor the in-situ state of the microstructure and to identify onset of dilatancy. Loading in the dilatant stress domain gives rise to the generation and propagation of cracks and to the increase of damage with strain. Effects of pore fluid pressure leading to reduction of effective pressure are only of importance in the dilatant domain, due to strain-induced increase of permeability. The coupling between stress and fluid flow is particularly dependent on the geometry of the fracture network. The experimental results give evidence that rock salt tends to become permeable at two specific con- ditions: (1) at large deviatoric stresses (see also Peach, 1991; Popp et al., 2001), and (2) at fluid pressures higher than the minimum principal stress. At conditions where fluids can permeate into the polycrystalline microstructure and generate a pore fluid pressure the physical properties of rock salt will be significantly changed.

  8. Trapped Inflation

    SciTech Connect

    Green, Daniel; Horn, Bart; /SLAC /Stanford U., Phys. Dept.; Senatore, Leonardo; /Princeton, Inst. Advanced Study /Harvard U., Phys. Dept. /Harvard-Smithsonian Ctr. Astrophys.; Silverstein, Eva; /SLAC /Stanford U., Phys. Dept.

    2009-06-19

    We analyze a distinctive mechanism for inflation in which particle production slows down a scalar field on a steep potential, and show how it descends from angular moduli in string compactifications. The analysis of density perturbations - taking into account the integrated effect of the produced particles and their quantum fluctuations - requires somewhat new techniques that we develop. We then determine the conditions for this effect to produce sixty e-foldings of inflation with the correct amplitude of density perturbations at the Gaussian level, and show that these requirements can be straightforwardly satisfied. Finally, we estimate the amplitude of the non-Gaussianity in the power spectrum and find a significant equilateral contribution.

  9. Controlled Thermal-Mechanical Processing of Tubes and Pipes for Enhanced Manufacturing and Performance

    Microsoft Academic Search

    Kolarik; Robert V

    2005-01-01

    The Alloy Steel Business of The Timken Company won an award for the controlled thermo-mechanical processing (CTMP) project and assembled a strong international public\\/private partnership to execute the project. The premise of the CTMP work was to combine Timken's product understanding with its process expertise and knowledge of metallurgical and deformation fundamentals developed during the project to build a predictive

  10. Mechanical Proof Systems for Logic II, Consensus Programs and Their Processing

    E-print Network

    Marek, Victor W.

    Mechanical Proof Systems for Logic II, Consensus Programs and Their Processing Helena Rasiowa and V the techniques of [Ra91] and of Logic programming ([Ap90, NS93]) we develop the processing techniques ([Ma88]), Orlowska ([Or90]) just to indicate to the reader that the issues of knowledge

  11. Implementing non-contact digitisation techniques within the mechanical design process

    Microsoft Academic Search

    Jim Clark

    2000-01-01

    The introduction of time compression technologies into the modern mechanical design process is now well established. Most major automotive and aerospace companies have invested, as have their Tier 1 suppliers. It has been identified that a bottleneck affecting all aspects of the cycle is the measurement process. In this paper we shall discuss potential benefits of adopting non-contact techniques. In

  12. A Probabilistic Mechanical Model for Simulating the Fatigue Failure Process in Metals

    Microsoft Academic Search

    Sidney A. Guralnick; Jamshid Mohammadi; Amy M. Kephart

    2011-01-01

    A model for simulating fatigue damage accumulation and the fatigue failure process in metals is presented. The simulation is achieved by modeling material behavior with a series of nonlinear mechanical springs with randomized behavior. With each applied stress, a certain number of springs rupture. The damage accumulation process is modeled by the number of springs that have ruptured during the

  13. Mechanism of contamination with aflatoxins of cotton seeds and products of their processing

    Microsoft Academic Search

    G. V. Tarasyuk; M. T. Tutakhozaev; R. A. Mirkina; T. T. Shakirov

    1988-01-01

    A possible mechanism of the contamination of cotton seeds and the products of their processing with aflatoxins has been studied. It has been found that the contamination of cotton seeds with aflatoxin takes place mainly on storage in the cotton ginning factory and the oils and fats combine. In the processing of the cotton seeds, part of the aflatoxins passes

  14. Beyond the Memory Mechanism: Person-Selective and Nonselective Processes in Recognition of Personally Familiar Faces

    ERIC Educational Resources Information Center

    Sugiura, Motoaki; Mano, Yoko; Sasaki, Akihiro; Sadato, Norihiro

    2011-01-01

    Special processes recruited during the recognition of personally familiar people have been assumed to reflect the rich episodic and semantic information that selectively represents each person. However, the processes may also include person nonselective ones, which may require interpretation in terms beyond the memory mechanism. To examine this…

  15. A new leakage mechanism of Co salicide and optimized process conditions [for CMOS

    Microsoft Academic Search

    Ken-ichi Goto; Atsuo Fushida; Junichi Watanabe; Takae Sukegawa; Yoko Tada; Tomoji Nakamura; Tatsuya Yamazaki; Toshihiro Sugii

    1999-01-01

    We have clarified a new leakage mechanism in Co salicide process for the ultrashallow junctions of 0.1-?m CMOS devices and revealed the optimum Co salicide process conditions for minimizing the leakage current. We found that leakage currents flow from many localized points that are randomly distributed in the function area. We successfully verified our localized leakage model via Monte Carlo

  16. The influence of processing variables on the mechanical properties of injection molded pregenerated microcomposites

    Microsoft Academic Search

    Michael A McLeod; Donald G Baird

    1999-01-01

    This work was concerned with addressing how injection molding process variables affected the final mechanical properties of composite materials based on poly(ethylene terephthalate) (PET) reinforced with pregenerated thermotropic liquid crystalline polymer (TLCP) fibrils, where the TLCP had a higher melting point than the PET. These composites, referred to as pregenerated microcomposites, were produced using a two step processing scheme. First,

  17. Analysis the physical essence of microscopic fluid-based wear process in the chemical mechanical planarization process

    NASA Astrophysics Data System (ADS)

    Han, Xuesong

    2011-09-01

    Chemical mechanical planarization (CMP) has become the process of choice for surface global planarization for materials surfaces in the fabrication of advanced multilevel integrated circuits (ICs) in microelectronic industry. The surface planarization in the CMP is mainly realized by the tribology behavior of nanoparticles. The suspending abrasive particles impinge on the surface at some velocity and angle thus imparting energy to the surface, resulting in strain, weakened bonds, and eventually material removal. Large-scale classical molecular dynamic (MD) simulation of interaction among nanoparticles and solid surface has been carried out to investigate the physical essence of fluid-based surface planarization process. The investigation shows that the plastic deformation plays an important role in this nanoscale wear process while the contribution of dislocations to the yield stress becomes insignificant. The depth of wear is gradually decreased which makes the fluid-based wear cannot realize the global surface planarization by itself. The abrasive wear process leads to characteristic surface topography running in the same direction as the sliding motion while the adhesive wear leads to the atoms of the substrate materials adhere to the opposing surface. The adhesion wear plays an important role at lower moving speed while the abrasive wear dominates the wear process at higher moving speed which means the moving speed is one of the key factors that influence the particle wear mechanism at the nanometer scale. Different tribology behavior involved in the CMP indicates that the final surface planarization is accomplished by the synergetic effect of different wear mechanism.

  18. Superconducting microfabricated ion traps

    E-print Network

    Wang, Shannon Xuanyue

    We fabricate superconducting ion traps with niobium and niobium nitride and trap single [superscript 88]Sr ions at cryogenic temperatures. The superconducting transition is verified and characterized by measuring the ...

  19. CONTINUOUS FLOW "RAIL-AND-TRAP" MICROFLUIDIC PROCESSORS FOR AUTONOMOUS

    E-print Network

    Lin, Liwei

    CONTINUOUS FLOW "RAIL-AND-TRAP" MICROFLUIDIC PROCESSORS FOR AUTONOMOUS BEAD-BASED MIXING, here we present a microfluidic "rail-and-trap" processor that functions autonomously under continuous step of multi-stage fluidic processes. Experimental results revealed railing efficiencies and trapping

  20. The photonic light trap—Improved light trapping in solar cells by angularly selective filters

    Microsoft Academic Search

    Marius Peters; Jan Christoph Goldschmidt; Thomas Kirchartz; Benedikt Bläsi

    2009-01-01

    A photonic light trap, i.e. a combination of an angularly selective filter and a light scattering process in a solar cell, results in potentially very efficient light trapping. Angularly selective filters are investigated theoretically and experimentally. One of the filters is used to realize a photonic light trap for a thin-film solar cell with amorphous-silicon absorber layer on a roughened

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

    Microsoft Academic Search

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

    2012-01-01

    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

  2. Microstructural Characterization and Mechanical Performance of Hot Work Tool Steel Processed by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Holzweissig, Martin Joachim; Taube, Alexander; Brenne, Florian; Schaper, Mirko; Niendorf, Thomas

    2015-04-01

    Microstructural characterization of hot work tool steel processed by selective laser melting was carried out. The findings shed light on the interrelationship between processing parameters and the microstructural evolution. It was found that the microstructure after layer-wise processing partially consists of metastable-retained austenite which transforms to martensite in a subsequent tensile test. This improves the mechanical properties of the hot work tool steel enabling direct application.

  3. Trap-induced photoconductivity in singlet fission pentacene diodes

    NASA Astrophysics Data System (ADS)

    Qiao, Xianfeng; Zhao, Chen; Chen, Bingbing; Luan, Lin

    2014-07-01

    This paper reports a trap-induced photoconductivity in ITO/pentacene/Al diodes by using current-voltage and magneto-conductance measurements. The comparison of photoconductivity between pentacene diodes with and without trap clearly shows that the traps play a critical role in generating photoconductivity. It shows that no observable photoconductivity is detected for trap-free pentacene diodes, while significant photoconductivity is observed in diodes with trap. This is because the initial photogenerated singlet excitons in pentacene can rapidly split into triplet excitons with higher binding energy prior to dissociating into free charge carriers. The generated triplet excitons react with trapped charges to release charge-carriers from traps, leading to a trap-induced photoconductivity in the single-layer pentacene diodes. Our studies elucidated the formation mechanisms of photoconductivity in pentacene diodes with extremely fast singlet fission rate.

  4. A Better Fly Trap

    NSDL National Science Digital Library

    Lawrence Hall of Science

    1979-01-01

    In this activity, learners observe fly behavior and then build a flytrap. They make more observations, compare the effectiveness of different traps, and modify their traps to increase their effectiveness. In doing so, learners consider what variables make for an effective trap as well as learning how to study the behavior of an animal. Even pesky flies provide an interesting challenge.

  5. Microstructural evolution and mechanical properties of high strength magneisum alloys fabricated by deformation processing

    NASA Astrophysics Data System (ADS)

    Mansoor, Bilal

    The goal of this research was to develop high strength Mg by thermo-mechanical processing. Several novel techniques were developed to impart large plastic strains on Mg alloys and Mg based composites. The main emphasis of this work was on investigating the effect of different processing schemes on grain-refinement and texture modification of processed material. The room-temperature and elevated-temperature mechanical behavior of processed-Mg was studied in detail. Biaxial corrugated pressing, also known as alternate biaxial reverse corrugation processing was applied to twin-roll cast AZ31 Mg and warm-extruded ZK60 Mg. Friction stir processing to partial depths was applied to thixomolded AM60 Mg and warm-extruded ZK60 Mg. A new process called "bending reverse-bending", was developed and applied to hot rolled AZ31-H24 Mg. A Mg/Al laminated composite was developed by hot pressing and rolling. In processed condition, Mg alloys exhibit enhancement in room-temperature strength and ductility, as well as elevated temperature formability. It was concluded that improvement in mechanical properties of processed-Mg is strongly influenced by grain size and precipitates; while ductility largely depends on resulting deformation textures.

  6. Relationship between microstructure, material distribution, and mechanical properties of sheep tibia during fracture healing process.

    PubMed

    Gao, Jiazi; Gong, He; Huang, Xing; Fang, Juan; Zhu, Dong; Fan, Yubo

    2013-01-01

    The aim of this study was to investigate the relationship between microstructural parameters, material distribution, and mechanical properties of sheep tibia at the apparent and tissue levels during the fracture healing process. Eighteen sheep underwent tibial osteotomy and were sacrificed at 4, 8, and 12 weeks. Radiographs and micro-computed tomography (micro-CT) scanning were taken for microstructural assessment, material distribution evaluation, and micro-finite element analysis. A displacement of 5% compressive strain on the longitudinal direction was applied to the micro-finite element model, and apparent and tissue-level mechanical properties were calculated. Principle component analysis and linear regression were used to establish the relationship between principle components (PCs) and mechanical parameters. Visible bony callus formation was observed throughout the healing process from radiographic assessment. Apparent mechanical property increased at 8 weeks, but tissue-level mechanical property did not increase significantly until 12 weeks. Three PCs were extracted from microstructural parameters and material distribution, which accounted for 87.592% of the total variation. The regression results showed a significant relationship between PCs and mechanical parameters (R>0.8, P<0.05). Results of this study show that microstructure and material distribution based on micro-CT imaging could efficiently predict bone strength and reflect the bone remodeling process during fracture healing, which provides a basis for exploring the fracture healing mechanism and may be used as an approach for fractured bone strength assessment. PMID:24046532

  7. The trapping of hydrogen in niobium by nitrogen interstitials

    Microsoft Academic Search

    G. Pfeiffer; H. Wipf

    1976-01-01

    The trapping of hydrogen in niobium by nitrogen interstitials was investigated by resistance measurements. The results showed that only about one hydrogen atom can be trapped per nitrogen interstitial at low temperatures and that the trapping enthalpy is 0.12+or-0.02 eV. Due to the trapping process the hydrogen-induced resistivity increase is reduced by about 40% and the occurrence of precipitations is

  8. Thermal Replication Trap

    NASA Astrophysics Data System (ADS)

    Braun, Dieter

    2011-03-01

    The hallmark of living matter is the replication of genetic molecules and their active storage against diffusion. We have argued in the past that thermal convection can host the million-fold accumulation even of single nucleotides and at the same time trigger exponential replication. Accumulation is driven by thermophoresis and convection in elongated chambers, replication by the inherent temperature cycling in convection. Optothermal pumping [2,3] allows to implement the thermal trap efficiently in a toroidal or linear geometry. Based on this method, we were in a position to combine accumulation and replication of DNA in the same chamber. As we are missing a solid chemistry of prebiotic replication, we used as a proxy reaction for to replication the polymerase chain reaction. Convective flow both drives the DNA replicating polymerase chain reaction (PCR) while concurrent thermophoresis accumulates the replicated 143 base pair DNA in bulk solution. The time constant for accumulation is 92 s while DNA is doubled every 50 s. The length of the amplified DNA is checked with thermophoresis. Finite element simulations confirm the findings. The experiments explore conditions in pores of hydrothermal rock which can serve as a model environment for the origin of life and has prospects towards the first autonomous evolution, hosting the Darwin process by molecular selection using the thermophoretic trap. On the other side, the implemented continuous evolution will be able to breed well specified DNA or RNA molecules in the future.

  9. Chemical aspects of the trapping and recovery of uranium hexafluoride and fluorine during remediation activities

    SciTech Connect

    Del Cul, G.D.; Toth, L.M. [Oak Ridge National Laboratory, TN (United States)

    1996-10-01

    Decontamination and decommission activities related to the Molten Salt Reactor Experiment (MSRE) involve the trapping and recovery of radiolitically generated uranium hexafluoride and fluorine. Although fission product radiolysis was known to generate F{sub 2}, the formation of UF{sub 6} and its transport from the fuel salt was unexpected. Some of these gaseous radiolysis products have been moving through the gas piping to a charcoal bed since the reactor was shut down in 1969. Current and planned remediation and clean-up activities involve the trapping of the gaseous products, deactivation and treatment of the activated charcoal bed, stabilization and reconditioning of the fuel salt, and recovery of the uranium. The chemical aspects of these processes, including radiolytic generation mechanisms, reactions between uranium hexafluoride and fluorine and trapping materials such as activated charcoal, activated alumina, and sodium fluoride, along with the analytical techniques used for the characterization of the materials and process control will be described.

  10. Personality Processes: Mechanisms by which Personality Traits “Get Outside the Skin”

    PubMed Central

    Hampson, Sarah E.

    2011-01-01

    It is time to better understand why personality traits predict consequential outcomes, which calls for a closer look at personality processes. Personality processes are mechanisms that unfold over time to produce the effects of personality traits. They include reactive and instrumental processes that moderate or mediate the association between traits and outcomes. These mechanisms are illustrated here by a selection of studies of traits representing the three broad domains of personality and temperament: negative emotionality, positive emotionality, and constraint. Personality processes are studied over the short-term, as in event-sampling studies, and over the long-term, as in lifespan research. Implications of findings from the study of processes are considered for resolving issues in models of personality structure, improving and extending methods of personality assessment, and identifying targets for personality interventions. PMID:21740225

  11. Mechanisms of enhanced total organic carbon elimination from oxalic acid solutions by electro-peroxone process.

    PubMed

    Wang, Huijiao; Yuan, Shi; Zhan, Juhong; Wang, Yujue; Yu, Gang; Deng, Shubo; Huang, Jun; Wang, Bin

    2015-09-01

    Electro-peroxone (E-peroxone) is a novel electrocatalytic ozonation process that combines ozonation and electrolysis process to enhance pollutant degradation during water and wastewater treatment. This enhancement has been mainly attributed to several mechanisms that increase O3 transformation to OH in the E-peroxone system, e.g., electro-generation of H2O2 from O2 at a carbon-based cathode and its subsequent peroxone reaction with O3 to OH, electro-reduction of O3 to OH at the cathode, and O3 decomposition to OH at high local pH near the cathode. To get more insight how these mechanisms contribute respectively to the enhancement, this study investigated total organic carbon (TOC) elimination from oxalic acid (OA) solutions by the E-peroxone process. Results show that the E-peroxone process significantly increased TOC elimination rate by 10.2-12.5 times compared with the linear addition of the individual rates of corresponding ozonation and electrolysis process. Kinetic analyses reveal that the electrochemically-driven peroxone reaction is the most important mechanism for the enhanced TOC elimination rate, while the other mechanisms contribute minor to the enhancement by a factor of 1.6-2.5. The results indicate that proper selection of electrodes that can effectively produce H2O2 at the cathode is critical to maximize TOC elimination in the E-peroxone process. PMID:25989593

  12. Accurate and simple assembly process of shape memory alloy tubular micro manipulator with a bias mechanism

    Microsoft Academic Search

    Takashi Mineta; Shinya Kudoh; Eiji Makino; Takahiro Kawashima; Takayuki Shibata

    2011-01-01

    This paper describes the fabrication and assembly of a tubular micro manipulator consisting of a TiNiCu shape memory alloy (SMA) actuator with a coaxial tubular bias mechanism of a TiNi super elasticity alloy. The TiNiCu actuator has meandering shaped springs connected to joint rings (O.D.: 970?m, I.D.: 910?m) in which a bias mechanism is inserted. To simplify the assembly process,

  13. Sisyphus cooling of electrically trapped polyatomic molecules.

    PubMed

    Zeppenfeld, Martin; Englert, Barbara G U; Glöckner, Rosa; Prehn, Alexander; Mielenz, Manuel; Sommer, Christian; van Buuren, Laurens D; Motsch, Michael; Rempe, Gerhard

    2012-11-22

    Polar molecules have a rich internal structure and long-range dipole-dipole interactions, making them useful for quantum-controlled applications and fundamental investigations. Their potential fully unfolds at ultracold temperatures, where various effects are predicted in many-body physics, quantum information science, ultracold chemistry and physics beyond the standard model. Whereas a wide range of methods to produce cold molecular ensembles have been developed, the cooling of polyatomic molecules (that is, with three or more atoms) to ultracold temperatures has seemed intractable. Here we report the experimental realization of optoelectrical cooling, a recently proposed cooling and accumulation method for polar molecules. Its key attribute is the removal of a large fraction of a molecule's kinetic energy in each cycle of the cooling sequence via a Sisyphus effect, allowing cooling with only a few repetitions of the dissipative decay process. We demonstrate the potential of optoelectrical cooling by reducing the temperature of about one million CH(3)F molecules by a factor of 13.5, with the phase-space density increased by a factor of 29 (or a factor of 70 discounting trap losses). In contrast to other cooling mechanisms, our scheme proceeds in a trap, cools in all three dimensions and should work for a large variety of polar molecules. With no fundamental temperature limit anticipated down to the photon-recoil temperature in the nanokelvin range, we expect our method to be able to produce ultracold polyatomic molecules. The low temperatures, large molecule numbers and long trapping times of up to 27 seconds should allow an interaction-dominated regime to be attained, enabling collision studies and investigation of evaporative cooling towards a Bose-Einstein condensate of polyatomic molecules. PMID:23151480

  14. TRAP1 Controls Mitochondrial Fusion/Fission Balance through Drp1 and Mff Expression

    PubMed Central

    Takamura, Hironori; Koyama, Yoshihisa; Matsuzaki, Shinsuke; Yamada, Kohei; Hattori, Tsuyoshi; Miyata, Shingo; Takemoto, Kana; Tohyama, Masaya; Katayama, Taiichi

    2012-01-01

    Mitochondria are dynamic organelles that change in response to extracellular stimuli. These changes are essential for normal mitochondrial/cellular function and are controlled by a tight balance between two antagonistic pathways that promote fusion and fission. Although some molecules have been identified to mediate the mitochondrial fusion and fission process, the underlying mechanisms remain unclear. Tumor necrosis factor receptor-associated protein 1 (TRAP1) is a mitochondrial molecule that regulates a variety of mitochondrial functions. Here, we examined the role of TRAP1 in the regulation of morphology. Stable TRAP1 knockdown cells showed abnormal mitochondrial morphology, and we observed significant decreases in dynamin-related protein 1 (Drp1) and mitochondrial fission factor (Mff), mitochondrial fission proteins. Similar results were obtained by transient knockdown of TRAP1 in two different cell lines, SH-SY5Y neuroblastoma cells and KNS-42 glioma cells. However, TRAP1 knockdown did not affect expression levels of fusion proteins. The reduction in Drp1 and Mff protein levels was rescued following treatment with the proteasome inhibitor MG132. These results suggest that TRAP1 regulates the expression of fission proteins and controls mitochondrial fusion/fission, which affects mitochondrial/cellular function. PMID:23284813

  15. REVIEW: Atomic clusters in a Penning trap: investigation of their properties and utilization as diagnostic tools

    NASA Astrophysics Data System (ADS)

    Walsh, N.; Herlert, A.; Martinez, F.; Marx, G.; Schweikhard, L.

    2009-08-01

    Ion traps are useful tools for many investigations on charged molecules and clusters. At ClusterTrap, the Penning trap is more than just a storage device. The split-ring electrodes allow radial excitations of the trapped-ion motion such that the ions can be centred in the trap or ejected from it, thus allowing the study of size-selected charged clusters. The extended ion-storage times have proven useful for the investigation of reactions and cluster-decay mechanisms. Collisional and laser excitation have been performed as well as electron-impact ionization for the characterization of cluster properties as a function of the cluster size. More recently, it was realized that the Penning trap set-up is particularly suitable for the production of polyanionic clusters. On the other hand, the clusters themselves are useful probes for the investigation of simultaneously stored charged particles. This paper contains examples of recent experimental results on the production and decay modes of polyanionic clusters, some of which also provide information about the properties of the electron-bath ensemble used in that process.

  16. A monolithic array of three-dimensional ion traps fabricated with conventional semiconductor technology.

    PubMed

    Wilpers, Guido; See, Patrick; Gill, Patrick; Sinclair, Alastair G

    2012-09-01

    The coherent control of quantum-entangled states of trapped ions has led to significant advances in quantum information, quantum simulation, quantum metrology and laboratory tests of quantum mechanics and relativity. All of the basic requirements for processing quantum information with arrays of ion-based quantum bits (qubits) have been proven in principle. However, so far, no more than 14 ion-based qubits have been entangled with the ion-trap approach, so there is a clear need for arrays of ion traps that can handle a much larger number of qubits. Traps consisting of a two-dimensional electrode array have undergone significant development, but three-dimensional trap geometries can create a superior confining potential. However, existing three-dimensional approaches, as used in the most advanced experiments with trap arrays, cannot be scaled up to handle greatly increased numbers of ions. Here, we report a monolithic three-dimensional ion microtrap array etched from a silica-on-silicon wafer using conventional semiconductor fabrication technology. We have confined individual (88)Sr(+) ions and strings of up to 14 ions in a single segment of the array. We have measured motional frequencies, ion heating rates and storage times. Our results demonstrate that it should be possible to handle several tens of ion-based qubits with this approach. PMID:22820742

  17. Neutrophil extracellular traps in physiology and pathology

    PubMed Central

    Manda, Aneta; Ara?na, Magdalena; Demkow, Urszula A.

    2014-01-01

    Neutrophil extracellular traps (NETs) are developed by nature to protect the body from furious invaders. On the other hand NET s can play an important role in human pathology. Recent studies have shown that neutrophils are able to perform beneficial suicide to create an unique microbicidal net composed from cellular content attached to chromatic frame. It is a powerful tool that primary serve as protector from severe infections, but this weapon is also a double ended sword of the immunity. If overproduced NET s provoke certain autoimmune diseases, coagulation disorders and even cancer metastases. Moreover, due to the competition between host and pathogens, the microorganism have developed a width repertoire of sophisticated evading mechanisms, like creation of polysaccharide capsule or changes in cell wall charge. Therefore it is important to increase the knowledge about paths underlying NET s formation and degradation processes if we want to efficiently fight with bacterial infections and certain diseases.

  18. Second international symposium on the mechanical integrity of process piping: Proceedings

    SciTech Connect

    Sims, J.R.; Aller, J.E.; Becht, C. IV; Reynolds, J.T.; Salot, W.J.; Sanders, B.J.; Springer, S.P. [eds.

    1996-07-01

    The mechanical integrity of process piping continues to be a major concern for companies in the petroleum refining, chemical, and other process industries. According to a 1993 report, 41% of the 170 largest industry losses in the hydrocarbon process industry resulted from failures of piping systems. This volume contains 30 papers divided into the following topical sections: Design, specifications, and erection; Materials of construction; Inspection and monitoring; Risk and reliability; Regulations and codes; and Fabrication, repair, and modification. All papers have been processed separately for inclusion on the data base.

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

    E-print Network

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

    2012-01-01

    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/eleme...

  20. Perfect error processing: Perfectionism-related variations in action monitoring and error processing mechanisms.

    PubMed

    Stahl, Jutta; Acharki, Manuela; Kresimon, Miriam; Völler, Frederike; Gibbons, Henning

    2015-08-01

    Showing excellent performance and avoiding poor performance are the main characteristics of perfectionists. Perfectionism-related variations (N=94) in neural correlates of performance monitoring were investigated in a flanker task by assessing two perfectionism-related trait dimensions: Personal standard perfectionism (PSP), reflecting intrinsic motivation to show error-free performance, and evaluative concern perfectionism (ECP), representing the worry of being poorly evaluated based on bad performance. A moderating effect of ECP and PSP on error processing - an important performance monitoring system - was investigated by examining the error (-related) negativity (Ne/ERN) and the error positivity (Pe). The smallest Ne/ERN difference (error-correct) was obtained for pure-ECP participants (high-ECP-low-PSP), whereas the highest difference was shown for those with high-ECP-high-PSP (i.e., mixed perfectionists). Pe was positively correlated with PSP only. Our results encouraged the cognitive-bias hypothesis suggesting that pure-ECP participants reduce response-related attention to avoid intense error processing by minimising the subjective threat of negative evaluations. The PSP-related variations in late error processing are consistent with the participants' high in PSP goal-oriented tendency to optimise their behaviour. PMID:26071226

  1. Low-damage direct patterning of silicon oxide mask by mechanical processing

    PubMed Central

    2014-01-01

    To realize the nanofabrication of silicon surfaces using atomic force microscopy (AFM), we investigated the etching of mechanically processed oxide masks using potassium hydroxide (KOH) solution. The dependence of the KOH solution etching rate on the load and scanning density of the mechanical pre-processing was evaluated. Particular load ranges were found to increase the etching rate, and the silicon etching rate also increased with removal of the natural oxide layer by diamond tip sliding. In contrast, the local oxide pattern formed (due to mechanochemical reaction of the silicon) by tip sliding at higher load was found to have higher etching resistance than that of unprocessed areas. The profile changes caused by the etching of the mechanically pre-processed areas with the KOH solution were also investigated. First, protuberances were processed by diamond tip sliding at lower and higher stresses than that of the shearing strength. Mechanical processing at low load and scanning density to remove the natural oxide layer was then performed. The KOH solution selectively etched the low load and scanning density processed area first and then etched the unprocessed silicon area. In contrast, the protuberances pre-processed at higher load were hardly etched. The etching resistance of plastic deformed layers was decreased, and their etching rate was increased because of surface damage induced by the pre-processing. These results show that etching depth can be controlled by controlling the etching time through natural oxide layer removal and mechanochemical oxide layer formation. These oxide layer removal and formation processes can be exploited to realize low-damage mask patterns. PMID:24948891

  2. Low-damage direct patterning of silicon oxide mask by mechanical processing.

    PubMed

    Miyake, Shojiro; Yamazaki, Shohei

    2014-01-01

    To realize the nanofabrication of silicon surfaces using atomic force microscopy (AFM), we investigated the etching of mechanically processed oxide masks using potassium hydroxide (KOH) solution. The dependence of the KOH solution etching rate on the load and scanning density of the mechanical pre-processing was evaluated. Particular load ranges were found to increase the etching rate, and the silicon etching rate also increased with removal of the natural oxide layer by diamond tip sliding. In contrast, the local oxide pattern formed (due to mechanochemical reaction of the silicon) by tip sliding at higher load was found to have higher etching resistance than that of unprocessed areas. The profile changes caused by the etching of the mechanically pre-processed areas with the KOH solution were also investigated. First, protuberances were processed by diamond tip sliding at lower and higher stresses than that of the shearing strength. Mechanical processing at low load and scanning density to remove the natural oxide layer was then performed. The KOH solution selectively etched the low load and scanning density processed area first and then etched the unprocessed silicon area. In contrast, the protuberances pre-processed at higher load were hardly etched. The etching resistance of plastic deformed layers was decreased, and their etching rate was increased because of surface damage induced by the pre-processing. These results show that etching depth can be controlled by controlling the etching time through natural oxide layer removal and mechanochemical oxide layer formation. These oxide layer removal and formation processes can be exploited to realize low-damage mask patterns. PMID:24948891

  3. Host feeding preferences of Anopheles species collected by manual aspiration, mechanical aspiration, and from a vehicle-mounted trap in the Toledo District, Belize, Central America.

    PubMed

    Grieco, John P; Achee, Nicole L; Andre, Richard G; Roberts, Donald R

    2002-12-01

    The host-feeding patterns of Anopheles albimanus, Anopheles vestitipennis, and Anopheles punctimacula from the Toledo District in southern Belize were studied with blood-fed females that were collected by manual aspiration, a backpack aspirator, and a vehicle-mounted trap for sampling in-flight mosquito populations. Female An. vestitipennis collected from both inside and outside house walls by manual aspiration tested positive for human blood meals (88 and 67%, respectively). At increasing distances from the houses, specimens of An. vestitipennis collected from vegetation with the backpack aspirator were equally positive for human and cattle blood (44 and 43%, respectively). In contrast, 68% of the An. albimanus specimens (148) collected by backpack aspiration tested positive for cattle blood. Engorged An. vestitipennis from vehicle-mounted trap collections tested positive for cattle (108) and human (52) blood. Almost all specimens of An. albimanus from these collections were positive for cow (95%). After analyzing the data from the An. vestitipennis samples using the feeding index, the ratio of human blood to all other bloodmeal sources showed indices greater than 1. Both An. albimanus and An. punctimacula fed mostly on cattle and rarely fed on humans. Foraging ratios for the 3 Anopheles species were very similar to the feeding indexes. Ratios based on data from all collection methods showed that An. vestitipennis feeds predominately on humans. The foraging ratios for An. albimanus demonstrated consistent preferences for nonhuman hosts. As with previous studies. An. albimanus seemed to prefer cattle and pigs to almost all other host species. PMID:12542188

  4. Efficiency at Maximum Power Output of a Quantum-Mechanical Brayton Cycle

    NASA Astrophysics Data System (ADS)

    Yuan, Yuan; He, Ji-Zhou; Gao, Yong; Wang, Jian-Hui

    2014-03-01

    The performance in finite time of a quantum-mechanical Brayton engine cycle is discussed, without introduction of temperature. The engine model consists of two quantum isoenergetic and two quantum isobaric processes, and works with a single particle in a harmonic trap. Directly employing the finite-time thermodynamics, the efficiency at maximum power output is determined. Extending the harmonic trap to a power-law trap, we find that the efficiency at maximum power is independent of any parameter involved in the model, but depends on the confinement of the trapping potential.

  5. 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.

  6. Feedback cooling of a single trapped ion

    E-print Network

    Pavel Bushev; Daniel Rotter; Alex Wilson; Francois Dubin; Christoph Becher; Juergen Eschner; Rainer Blatt; Viktor Steixner; Peter Rabl; Peter Zoller

    2005-09-19

    Based on a real-time measurement of the motion of a single ion in a Paul trap, we demonstrate its electro-mechanical cooling below the Doppler limit by homodyne feedback control (cold damping). The feedback cooling results are well described by a model based on a quantum mechanical Master Equation.

  7. Laser trapping of {sup 21}Na atoms

    SciTech Connect

    Lu, Zheng-Tian

    1994-09-01

    This thesis describes an experiment in which about four thousand radioactive {sup 21}Na (t{sub l/2} = 22 sec) atoms were trapped in a magneto-optical trap with laser beams. Trapped {sup 21}Na atoms can be used as a beta source in a precision measurement of the beta-asymmetry parameter of the decay of {sup 21}Na {yields} {sup 21}Ne + {Beta}{sup +} + v{sub e}, which is a promising way to search for an anomalous right-handed current coupling in charged weak interactions. Although the number o trapped atoms that we have achieved is still about two orders of magnitude lower than what is needed to conduct a measurement of the beta-asymmetry parameter at 1% of precision level, the result of this experiment proved the feasibility of trapping short-lived radioactive atoms. In this experiment, {sup 21}Na atoms were produced by bombarding {sup 24}Mg with protons of 25 MeV at the 88 in. Cyclotron of Lawrence Berkeley Laboratory. A few recently developed techniques of laser manipulation of neutral atoms were applied in this experiment. The {sup 21}Na atoms emerging from a heated oven were first transversely cooled. As a result, the on-axis atomic beam intensity was increased by a factor of 16. The atoms in the beam were then slowed down from thermal speed by applying Zeeman-tuned slowing technique, and subsequently loaded into a magneto-optical trap at the end of the slowing path. The last two chapters of this thesis present two studies on the magneto-optical trap of sodium atoms. In particular, the mechanisms of magneto-optical traps at various laser frequencies and the collisional loss mechanisms of these traps were examined.

  8. Magnetically processed carbon nanotube\\/epoxy nanocomposites: Morphology, thermal, and mechanical properties

    Microsoft Academic Search

    Mohamed Abdalla; Derrick Dean; Merlin Theodore; Jennifer Fielding; Elijah Nyairo; Gary Price

    2010-01-01

    The processing-structure–property relationships of multiwalled carbon nanotubes (MWNTs)\\/epoxy nanocomposites processed with a magnetic field have been studied. Samples were prepared by dispersing the nanotube in the epoxy and curing under an applied magnetic field. The nanocomposite morphology was characterized with Raman spectroscopy and wide angle X-ray scattering, and correlated with thermo-mechanical properties. The modulus parallel to the alignment direction, as

  9. Solar cell and I.C. aspects of ingot-to-slice mechanical processing

    Microsoft Academic Search

    L. D. Dyer

    1985-01-01

    Intensive efforts have been put into the growth of silicon crystals to suit today's solar cell and integrated circuit requirements. Each step of processing the crystal must also receive concentrated attention to preserve the grown-in perfection and to provide a suitable device-ready wafer at reasonable cost. A comparison is made between solar cell and I.C. requirements on the mechanical processing

  10. Specific surface area and chemical reactivity of quartz powders during mechanical processing

    SciTech Connect

    Meloni, Paola [Dipartimento di Ingegneria Chimica e Materiali, Universita degli Studi di Cagliari, piazza d'Armi, I-09123 Cagliari (Italy) [Dipartimento di Ingegneria Chimica e Materiali, Universita degli Studi di Cagliari, piazza d'Armi, I-09123 Cagliari (Italy); Laboratorio per lo studio dei Materiali 'Colle di Bonaria', Universita degli Studi di Cagliari, via Ravenna, I-09100 Cagliari (Italy); Carcangiu, Gianfranco [Laboratorio per lo studio dei Materiali 'Colle di Bonaria', Universita degli Studi di Cagliari, via Ravenna, I-09100 Cagliari (Italy) [Laboratorio per lo studio dei Materiali 'Colle di Bonaria', Universita degli Studi di Cagliari, via Ravenna, I-09100 Cagliari (Italy); Istituto di Geologia Ambientale e Geoingegneria (IGAG), CNR, piazza d'Armi, I-09123 Cagliari (Italy); Delogu, Francesco, E-mail: delogu@dicm.unica.it [Dipartimento di Ingegneria Chimica e Materiali, Universita degli Studi di Cagliari, piazza d'Armi, I-09123 Cagliari (Italy)] [Dipartimento di Ingegneria Chimica e Materiali, Universita degli Studi di Cagliari, piazza d'Armi, I-09123 Cagliari (Italy)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Quartz powders were submitted to mechanical processing. Black-Right-Pointing-Pointer The specific surface area and the chemical reactivity increased. Black-Right-Pointing-Pointer A model was developed to describe the observed processes. Black-Right-Pointing-Pointer The amount of powder processed at impact was estimated. Black-Right-Pointing-Pointer The surface density of reactive centers was also estimated by using a test reaction. -- Abstract: The present work focuses on the specific surface area increase, and on the related chemical reactivity enhancement of quartz powders submitted to mechanical processing. The mechanical treatment was carried out in a suitably developed ball mill allowing the control of the frequency and energy of the impacts between ball and reactor. The specific surface area was directly measured by nitrogen physisorption, whereas electron microscopy was used to determine the size distribution of powder particles. Based on the experimental results, a simplified mathematical model was developed to describe the process of specific surface area increase on a phenomenological basis. The model permits to gain valuable information on the amount of powder processed in individual impacts. The density of reactive centers at the surface of powder particles was also estimated by using the neutralization of a free radical as a test reaction. It is shown that the surface density of reactive centers increases with the energy of collisions.

  11. Influence of different processing techniques on the mechanical properties of used tires in embankment construction

    SciTech Connect

    Edincliler, Ayse, E-mail: aedinc@boun.edu.t [Department of Earthquake Engineering, Kandilli Observatory and Earthquake Research Institute, Bogazici University, Cengelkoy, 34684 Istanbul (Turkey); Baykal, Goekhan; Saygili, Altug [Civil Engineering Department, Bogazici University, 34342 Istanbul (Turkey)

    2010-06-15

    Use of the processed used tires in embankment construction is becoming an accepted way of beneficially recycling scrap tires due to shortages of natural mineral resources and increasing waste disposal costs. Using these used tires in construction requires an awareness of the properties and the limitations associated with their use. The main objective of this paper is to assess the different processing techniques on the mechanical properties of used tires-sand mixtures to improve the engineering properties of the available soil. In the first part, a literature study on the mechanical properties of the processed used tires such as tire shreds, tire chips, tire buffings and their mixtures with sand are summarized. In the second part, large-scale direct shear tests are performed to evaluate shear strength of tire crumb-sand mixtures where information is not readily available in the literature. The test results with tire crumb were compared with the other processed used tire-sand mixtures. Sand-used tire mixtures have higher shear strength than that of the sand alone and the shear strength parameters depend on the processing conditions of used tires. Three factors are found to significantly affect the mechanical properties: normal stress, processing techniques, and the used tire content.

  12. Trace detection of organic compounds in complex sample matrixes by single photon ionization ion trap mass spectrometry: real-time detection of security-relevant compounds and online analysis of the coffee-roasting process.

    PubMed

    Schramm, Elisabeth; Kürten, Andreas; Hölzer, Jasper; Mitschke, Stefan; Mühlberger, Fabian; Sklorz, Martin; Wieser, Jochen; Ulrich, Andreas; Pütz, Michael; Schulte-Ladbeck, Rasmus; Schultze, Rainer; Curtius, Joachim; Borrmann, Stephan; Zimmermann, Ralf

    2009-06-01

    An in-house-built ion trap mass spectrometer combined with a soft ionization source has been set up and tested. As ionization source, an electron beam pumped vacuum UV (VUV) excimer lamp (EBEL) was used for single-photon ionization. It was shown that soft ionization allows the reduction of fragmentation of the target analytes and the suppression of most matrix components. Therefore, the combination of photon ionization with the tandem mass spectrometry (MS/MS) capability of an ion trap yields a powerful tool for molecular ion peak detection and identification of organic trace compounds in complex matrixes. This setup was successfully tested for two different applications. The first one is the detection of security-relevant substances like explosives, narcotics, and chemical warfare agents. One test substance from each of these groups was chosen and detected successfully with single photon ionization ion trap mass spectrometry (SPI-ITMS) MS/MS measurements. Additionally, first tests were performed, demonstrating that this method is not influenced by matrix compounds. The second field of application is the detection of process gases. Here, exhaust gas from coffee roasting was analyzed in real time, and some of its compounds were identified using MS/MS studies. PMID:19408912

  13. Rheology, processing, and mechanical properties of thermoplastic/graphite fiber composites

    SciTech Connect

    Scobbo, J.J. Jr.

    1989-01-01

    Various cause and effect relations between the rheology, processing and mechanical properties of poly(ether ether ketone) (PEEK) and poly(arylene sulfide) (PAS) matrix composites were studied. The test methods and characterization schemes used emphasize novel techniques for characterizing composites that have not been used previously. A dynamic mechanical analyzer has been modified and used to characterize transition temperatures of the neat matrix resins and the 60 volume percent continuous graphite fiber reinforced composites. Transitions related to local order may have been found in PEEK at 380{degree}C and PAS at 345{degree}C. Transitions such as these have not been reported previously using dynamic mechanical analysis. Basic rheological behavior of the resins has been studied using dynamic mechanical analysis. Similar dynamic tests were performed on PEEK and PAS matrix unidirectional prepreg tape-based laminates. Tests were performed for the first time in simple shear with the matrix in the melt state. Simple shear deformation is of interest because it represents flow behavior of laminated composites in processing operations such as thermoforming. A simple model of resin layers between fibrous plates describes the observed behavior. A bending mode dynamic test has been developed to determine laminate softening temperatures. This test has been shown to be beneficial in the characterization of composite elastic properties at room temperature. The test requires less material and labor than other more common mechanical property tests. Processing studies were conducted where the radiative heating of laminates was simulated to determine optimum thermoforming cycle times.

  14. Mechanical Modelling of Pultrusion Process: 2D and 3D Numerical Approaches

    NASA Astrophysics Data System (ADS)

    Baran, Ismet; Hattel, Jesper H.; Akkerman, Remko; Tutum, Cem C.

    2015-02-01

    The process induced variations such as residual stresses and distortions are a critical issue in pultrusion, since they affect the structural behavior as well as the mechanical properties and geometrical precision of the final product. In order to capture and investigate these variations, a mechanical analysis should be performed. In the present work, the two dimensional (2D) quasi-static plane strain mechanical model for the pultrusion of a thick square profile developed by the authors is further improved using generalized plane strain elements. In addition to that, a more advanced 3D thermo-chemical-mechanical analysis is carried out using 3D quadratic elements which is a novel application for the numerical modelling of the pultrusion process. It is found that the 2D mechanical models give relatively reasonable and accurate stress and displacement evolutions in the transverse direction as compared to the 3D model. Moreover, the generalized plane strain model predicts the longitudinal process induced stresses more similar to the ones calculated in the 3D model as compared with the plane strain model.

  15. High performance of mechanical and electrical properties of Cu-Cr-Zr alloy sheets produced by ARB process and additional thermo-mechanical treatment

    NASA Astrophysics Data System (ADS)

    Akita, T.; Kitagawa, K.; Kita, K.; Gotoh, M.; Hirose, Y.; Tsuji, N.

    2010-07-01

    The additional cold rolling and the aging process were applied to Cu-0.85Cr-0.07Zr alloy sheets processed by ARB, and mechanical properties and structural information were investigated for the purpose of further improvement of the mechanical properties and the electrical conductivity. From the results of the tensile test and the measurement of electrical conductivity, ARB/aged/CR was most appropriate processing in order to achieve technical advantages. The high tensile strength of 745 MPa and the high electrical conductivity of 68 %IACS were obtained simultaneously. In addition, the improvement of incomplete boundaries generated during ARB processing was possible by thermo-mechanical treatment.

  16. Fatigue behaviour analysis of mechanical components subject to random bimodal stress process: frequency domain approach

    Microsoft Academic Search

    Claudio Braccesi; Filippo Cianetti; Guido Lori; Dario Pioli

    2005-01-01

    A frequency domain approach to fatigue life evaluation is an important task in the design of mechanical components subject to random loads.The greatest advantages of this method are the computational efficiency and the capability to give a synthetic representation of a random process. The importance of this method is clear, especially when it is used in the postprocessing phase of

  17. Recycling of construction and demolition waste via a mechanical sorting process

    Microsoft Academic Search

    Wen-Ling Huang; Dung-Hung Lin; Ni-Bin Chang; Kuen-Song Lin

    2002-01-01

    This paper assesses a construction and demonstration (C&D) waste recycling program in relation to technical, institutional, and economic considerations. The focus is primarily placed on a feasibility study for a new mechanical sorting process that was installed with several unit operations, including bar screening, trommel screening, air classifier, disk screening, and final manual sorting. Lab analyses, consisting of sieve analysis,

  18. Thermo-Mechanical Model of Solidification Processes with Seid Koric and Brian G. Thomas

    E-print Network

    Thomas, Brian G.

    implemented into Abaqus, (Abaqus Inc., 2005) using a user-defined subroutine (UMAT) to integrate Casting, Finite Elements, Abaqus, UMAT, CON2D, Fixed Grid, Solidification, Thin Slab Casting, Funnel MoldThermo-Mechanical Model of Solidification Processes with Abaqus Seid Koric and Brian G. Thomas

  19. Recovering copper from spent lithium ion battery by a mechanical separation process

    Microsoft Academic Search

    Shuguang Zhu; Wenzhi He; Guangming Li; Xu Zhou; Juwen Huang; Xiaojun Zhang

    2011-01-01

    were separated from spent LIBs with aim to recycle all valuable components as possible. The spent LIBs were dismantled first, then the mechanical pulverization and sieving process was adopted in the separation of anodes. Owing to low bonding force between graphite carbon particles and copper foil, graphite carbon can easily drop off and be separated when anode materials were struck.

  20. Effect of silicon solar cell processing parameters and crystallinity on mechanical strength

    Microsoft Academic Search

    V. A. Popovich; A. Yunus; M. Janssen; I. M. Richardson; I. J. Bennett

    2011-01-01

    Silicon wafer thickness reduction without increasing the wafer strength leads to a high breakage rate during subsequent handling and processing steps. Cracking of solar cells has become one of the major sources of solar module failure and rejection. Hence, it is important to evaluate the mechanical strength of solar cells and influencing factors. The purpose of this work is to

  1. Effect of microstructure and processing parameters on mechanical strength of multicrystalline silicon solar cells

    Microsoft Academic Search

    V. A. Popovich; A. Yunus; M. Janssen; I. J. Bennett; I. M. Richardson

    2010-01-01

    Silicon wafer thickness reduction without increasing the wafer strength leads to a high breakage rate during subsequent handling and processing steps. Cracking of solar cells has become one of the major sources of solar module failure and rejection. Hence, it is important to evaluate the mechanical strength of solar cells and influencing factors. The purpose of this work is to

  2. Combustion synthesis/quasi-isostatic pressing of TiCNiTi cermets: processing and mechanical response

    E-print Network

    Meyers, Marc A.

    Combustion synthesis/quasi-isostatic pressing of TiC­NiTi cermets: processing and mechanical and alumina particulate before initiation of the combustion reaction. The sample was ignited within the particulate and subjected to a uniaxial load immediately after passage of the combustion wave

  3. Using a nonlinear mechanism to speed up the neural optimization processes

    Microsoft Academic Search

    Zeng-Guang Hou; Feng-Shui Jing; Min Tan

    2002-01-01

    Recurrent neural networks based on gradient descent algorithms have been widely used in computation of various optimization and control problems. With the aid of a nonlinear mechanism, an improved method for accelerating the neural computation of optimization processes is proposed. We analyze its convergence property and compare it with other methods. Finally, we give simulation results to show its effectiveness

  4. City of San Diego This page outlines solar PV incentives, financing mechanisms, permitting process, and

    E-print Network

    tax bill. For more information: www.californiafirst.org #12;· Secured Financing o Home Equity LinesCity of San Diego This page outlines solar PV incentives, financing mechanisms, permitting process and Electric. To skip directly to each section please use these hyperlinks: Find an Installer | Financing

  5. Mechanically Strain-Induced Modification of Selenium Powders in the Amorphization Process

    Microsoft Academic Search

    Makoto Fuse; Yoshiyuki Shirakawa; Atsuko Shimosaka; Jusuke Hidaka

    2003-01-01

    For the fabrication of particles designed in the nanoscale structure, or the nanostructural modification of particles using mechanical grinding process, selenium powders ground by a planetary ball mill at various rotational speeds have been investigated. Structural analyses, such as particle size distributions, crystallite sizes, lattice strains and nearest neighbour distances were performed using X-ray diffraction, scanning electron microscopy and dynamical

  6. Mechanical Study of Copper Bonded at Low Temperature using Spark Plasma Sintering Process

    E-print Network

    Paris-Sud XI, Université de

    Mechanical Study of Copper Bonded at Low Temperature using Spark Plasma Sintering Process Bassem.allard@insa-lyon.fr Keywords: Copper bonding, Spark Plasma Sintering, Tensile test Abstract. Bonding of high purity polished copper was investigated using the Spark Plasma Sintering technique (SPS) showing the effect of SPS

  7. City of Anaheim This page outlines solar PV incentives, financing mechanisms, permitting process, and

    E-print Network

    City of Anaheim This page outlines solar PV incentives, financing mechanisms, permitting process | Incentives | Permitting | Interconnection Contact Information City of Anaheim Building Division 200 S will: Locate financing programs to fit your needs Apply for rebates and incentives on your behalf

  8. City of Pasadena This page outlines solar financing mechanisms, incentives, permitting process, and interconnection

    E-print Network

    City of Pasadena This page outlines solar financing mechanisms, incentives, permitting process | Incentives | Permitting | Interconnection Contact Information Pasadena Water and Power (PWP) Pasadena Solar your needs Apply for rebates and incentives on your behalf Apply for local permits Install your PV

  9. City of Santa Ana This page outlines solar PV incentives, financing mechanisms, permitting process, and

    E-print Network

    City of Santa Ana This page outlines solar PV incentives, financing mechanisms, permitting process | Financing | Incentives | Permitting | Interconnection Contact Information City of Santa Ana Planning for rebates and incentives on your behalf Apply for local permits Install your PV system Arrange for your

  10. About the influence of mechanical comminution processes on saturation magnetization of strontium ferrites

    Microsoft Academic Search

    U. Heinecke; C. Bernhardt; H. Heegn

    1984-01-01

    The influence of the mechanical comminution process on the coercive field of hardmagnetic ferrites is well known. But, there is a strong effect on the saturation magnetization of strontium ferrite as well. Using a special type of a vibration mill the saturation magnetization decreases to 0.084 T and increases up to 0.22 T by further enlarging the milling time. The

  11. Rheological and mechanical properties of polyamide 6 modified by electron-beam initiated mediation process

    NASA Astrophysics Data System (ADS)

    Shin, Boo Young; Kim, Jae Hong

    2015-07-01

    Polyamide (PA6) has been modified by electron-beam initiated mediator process to improve drawbacks of PA6. Glycidyl methacrylate (GMA) was chosen as a reactive mediator for modification process of PA6. The mixture of the PA6 and GMA was prepared by using a twin-screw extruder, and then the mixture was exposed to electron-beam irradiation at various doses at room temperature. The modified PA6 were characterized by observing rheological and mechanical properties and compared virgin PA6. Thermal properties, water absorption, and gel fraction were also investigated. Tight gel was not found even when PA6 was irradiated at 200 kGy. Complex viscosity and storage modulus of PA6 were remarkably increased by electron-beam irradiation with medium of GMA. Maximum increase in complex viscosity was 75 times higher than virgin PA6 at 0.1 rad/s when it was irradiated at 200 kGy with the GMA. Mechanical properties were also improved without scarifying of processability. The reaction mechanisms for the mediation process with the reactive mediator of GMA were estimated to elucidate the cause of significantly enhanced rheological and mechanical properties without loss of thermoplasticity.

  12. Applying the Decoding the Disciplines Process to Teaching Structural Mechanics: An Autoethnographic Case Study

    ERIC Educational Resources Information Center

    Tingerthal, John Steven

    2013-01-01

    Using case study methodology and autoethnographic methods, this study examines a process of curricular development known as "Decoding the Disciplines" (Decoding) by documenting the experience of its application in a construction engineering mechanics course. Motivated by the call to integrate what is known about teaching and learning…

  13. Process controls on the development of stratigraphic trap potential on the margins of confined turbidite systems and aids to reservoir evaluation

    Microsoft Academic Search

    William McCaffrey; Benjamin Kneller

    Stratigraphic trapping at pinch-out margins is a key feature of many turbidite-hosted hydrocarbon reservoirs. In systems confined by lat- eral or oblique frontal slopes, outcrop studies show that there is a continuum between two geometries of pinch-out configuration. In type A, turbidites thin onto the confining surface—although the final sandstone pinch-out is commonly abrupt—and individual beds tend not to erode

  14. Mechanical Behaviour of Conventional Materials at Experimental Conditions of Deep Drawing Technological Process

    NASA Astrophysics Data System (ADS)

    Nikolov, N.; Pashkouleva, D.; Kavardzhikov, V.

    2012-09-01

    The paper deals with experimental investigations on the mechanical behaviour of body-centred-cubic (BCC) and face-centred-cubic (FCC)-conventionally structured sheet metalic-metalic materials under stress-strain conditions of a deep drawing process determined by a coefficient close to the limiting one for Steel 08 and punch diameter of 50 mm. The mechanical characteristics of the investigated materials are identified by one-dimensional tension tests. The materials' responses, as results of identical loading conditions, are described by the change of blank sizes and characteristics of the forming processes. The chosen deformation path ensures obtaining a qualitative steel piece and leads to failures of aluminium and brass blanks. The reported results could be useful for investigations and predictions of the mechanical responses of such type metallic structures applying microscopic instrumented observations and numerical simulations.

  15. Trapping effects on inflation

    E-print Network

    Wolung Lee; Kin-Wang Ng; I-Chin Wang; Chun-Hsien Wu

    2011-08-23

    We develop a Lagrangian approach based on the influence functional method so as to derive self-consistently the Langevin equation for the inflaton field in the presence of trapping points along the inflaton trajectory. The Langevin equation exhibits the backreaction and the fluctuation-dissipation relation of the trapping. The fluctuation is induced by a multiplicative colored noise that can be identified as the the particle number density fluctuations and the dissipation is a new effect that may play a role in the trapping with a strong coupling. In the weak coupling regime, we calculate the power spectrum of the noise-driven inflaton fluctuations for a single trapping point and studied its variation with the trapping location. We also consider a case with closely spaced trapping points and find that the resulting power spectrum is blue.

  16. 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.

  17. Modeling the coupled mechanics, transport, and growth processes in collagen tissues.

    SciTech Connect

    Holdych, David J.; Nguyen, Thao D.; Klein, Patrick A.; in't Veld, Pieter J.; Stevens, Mark Jackson

    2006-11-01

    The purpose of this project is to develop tools to model and simulate the processes of self-assembly and growth in biological systems from the molecular to the continuum length scales. The model biological system chosen for the study is the tendon fiber which is composed mainly of Type I collagen fibrils. The macroscopic processes of self-assembly and growth at the fiber scale arise from microscopic processes at the fibrillar and molecular length scales. At these nano-scopic length scales, we employed molecular modeling and simulation method to characterize the mechanical behavior and stability of the collagen triple helix and the collagen fibril. To obtain the physical parameters governing mass transport in the tendon fiber we performed direct numerical simulations of fluid flow and solute transport through an idealized fibrillar microstructure. At the continuum scale, we developed a mixture theory approach for modeling the coupled processes of mechanical deformation, transport, and species inter-conversion involved in growth. In the mixture theory approach, the microstructure of the tissue is represented by the species concentration and transport and material parameters, obtained from fibril and molecular scale calculations, while the mechanical deformation, transport, and growth processes are governed by balance laws and constitutive relations developed within a thermodynamically consistent framework.

  18. Modular cryostat for ion trapping with surface-electrode ion traps

    NASA Astrophysics Data System (ADS)

    Vittorini, Grahame; Wright, Kenneth; Brown, Kenneth R.; Harter, Alexa W.; Doret, S. Charles

    2013-04-01

    We present a simple cryostat purpose built for use with surface-electrode ion traps, designed around an affordable, large cooling power commercial pulse tube refrigerator. A modular vacuum enclosure with a single vacuum space facilitates interior access and enables rapid turnaround and flexibility for future modifications. Long rectangular windows provide nearly 360° of optical access in the plane of the ion trap, while a circular bottom window near the trap enables NA 0.4 light collection without the need for in-vacuum optics. We evaluate the system's mechanical and thermal characteristics and we quantify ion trapping performance by trapping 40Ca+, finding small stray electric fields, long ion lifetimes, and low ion heating rates.

  19. Modular cryostat for ion trapping with surface-electrode ion traps.

    PubMed

    Vittorini, Grahame; Wright, Kenneth; Brown, Kenneth R; Harter, Alexa W; Doret, S Charles

    2013-04-01

    We present a simple cryostat purpose built for use with surface-electrode ion traps, designed around an affordable, large cooling power commercial pulse tube refrigerator. A modular vacuum enclosure with a single vacuum space facilitates interior access and enables rapid turnaround and flexibility for future modifications. Long rectangular windows provide nearly 360° of optical access in the plane of the ion trap, while a circular bottom window near the trap enables NA 0.4 light collection without the need for in-vacuum optics. We evaluate the system's mechanical and thermal characteristics and we quantify ion trapping performance by trapping (40)Ca(+), finding small stray electric fields, long ion lifetimes, and low ion heating rates. PMID:23635186

  20. The Effect of Process Parameters on the Microstructure and Mechanical Properties of Semisolid Cast Al6061

    NASA Astrophysics Data System (ADS)

    Hajihashemi, Mahdi; Niroumand, Behzad; Shamanian, Morteza

    2015-04-01

    An examination of the microstructure and mechanical properties of aluminum 6061 alloy samples produced by a miniature cooling slope is presented. The effects of several process parameters including pouring rate, cooling slope angle, superheat and cooling slope length on the microstructure and mechanical characteristics of the samples were investigated. An attempt was made to use the two-level factorial design method to determine the relationships between the process parameters and the properties of the semisolid aluminum 6061 alloy manufactured by the miniature cooling slope. Finally, an optimum processing region was identified. The interaction between the cooling slope length and the pouring rate ( BC); the interaction among the superheat, the pouring rate, and the cooling slope length ( ABC); and the cooling slope length (C), in the order mentioned, were identified as the most important effects.

  1. Pultruded fiber reinforced PU/PMMA IPNs composites -- processability and mechanical properties

    SciTech Connect

    Chen, C.H.; Ma, C.C.M. [National Tsing Hua Univ., Hsin-chu (Taiwan, Province of China). Institute of Chemical Engineering

    1993-12-31

    This paper presents a proprietary process developed to manufacture polyurethane (PU)/poly methyl methacrylate (PMMA) interpenetrating polymer network (IPNs) pultruded composites. The IPNs prepolymer synthesized in this study was prepared from the blends of MMA prepolymer and blocked NCO-terminated PU prepolymer. The processability, mechanical and dynamic mechanical properties of glass fiber reinforced PU/PMMA IPNs composites have been studied. From the investigation of the pot life of resins, the reactivity of resin and fiber wet-out, it was found that the PU/PMMA IPNs show excellent processability for pultrusion. Results show that the tan{delta} of IPNs composites shifts to the higher temperature with increasing PMMA content, and dynamic shear storage modulus(G{prime}) increases with PMMA content. The flexural strength, flexural modulus and hardness of IPNs composites increase with PMMA content, however, the impact strength and swelling ratio of IPNs composites decrease with the increasing of PMMA content.

  2. Improvement of Structural and Mechanical Properties of Al-1100 Alloy via Friction Stir Processing

    NASA Astrophysics Data System (ADS)

    Mosallaee, M.; Dehghan, M.

    2014-10-01

    In the present study, the relationship between structural and mechanical properties of friction stir processed Al-1100 alloy and process parameters (tool rotation rate: ? and traverse speed: ?) was studied to get an better understanding and optimizing the friction stir processing (FSP) condition of this alloy. Microstructural studies revealed that increasing of ? up to 720 rpm resulted in grain refinement in the stirred zone (SZ), but higher increasing of ? caused grain growth in this zone. These variations of SZ grain size illustrated that the prevailing factor that determined the SZ grain size was plastic deformation at first and thereafter, peak temperature in the SZ. Mechanical properties investigations were in accordance with microstructural findings and illustrated that optimized FSP condition for Al-1100 alloy was 720 rpm and 20 mm/min. Optimized FSP condition resulted in a significant improvement of tensile strength and elongation up to 22 and 8% of those of base metal, respectively.

  3. Petrochemical industry standards activity aimed at improving the mechanical integrity of process piping

    SciTech Connect

    Reynolds, J.T. [Shell Oil Products Co., Houston, TX (United States)

    1996-07-01

    This paper will cover numerous changes being made to existing standards and several new standards being created, all focusing on increasing mechanical integrity of petrochemical industry process piping. Those new standards include ones for (1) Risk-Based Inspection (2) Fitness for Service Analysis, (3) Positive Material Identification, and (4) In-service Inspection and Maintenance for Process Piping. A progress report is included for the Process Industry Practices (PIP) being created to consolidate individual company piping standards into one consistent industry set. And finally, recent initiatives toward standards cooperation/coordination between the American Petroleum Institute(API), American Society of Mechanical Engineers (ASME), International Standards Organization (ISO) and National Board are highlighted.

  4. Microstructure and Mechanical Behavior of 17-4 Precipitation Hardenable Steel Processed by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Rafi, H. Khalid; Pal, Deepankar; Patil, Nachiket; Starr, Thomas L.; Stucker, Brent E.

    2014-12-01

    The mechanical behavior and the microstructural evolution of 17-4 precipitation hardenable (PH) stainless steel processed using selective laser melting have been studied. Test coupons were produced from 17-4 PH stainless steel powder in argon and nitrogen atmospheres. Characterization studies were carried out using mechanical testing, optical microscopy, scanning electron microscopy, and x-ray diffraction. The results show that post-process heat treatment is required to obtain typically desired tensile properties. Columnar grains of smaller diameters (<2 µm) emerged within the melt pool with a mixture of martensite and retained austenite phases. It was found that the phase content of the samples is greatly influenced by the powder chemistry, processing environment, and grain diameter.

  5. Microstructure and Mechanical Behavior of 17-4 Precipitation Hardenable Steel Processed by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Rafi, H. Khalid; Pal, Deepankar; Patil, Nachiket; Starr, Thomas L.; Stucker, Brent E.

    2014-09-01

    The mechanical behavior and the microstructural evolution of 17-4 precipitation hardenable (PH) stainless steel processed using selective laser melting have been studied. Test coupons were produced from 17-4 PH stainless steel powder in argon and nitrogen atmospheres. Characterization studies were carried out using mechanical testing, optical microscopy, scanning electron microscopy, and x-ray diffraction. The results show that post-process heat treatment is required to obtain typically desired tensile properties. Columnar grains of smaller diameters (<2 µm) emerged within the melt pool with a mixture of martensite and retained austenite phases. It was found that the phase content of the samples is greatly influenced by the powder chemistry, processing environment, and grain diameter.

  6. Development of the Process for the Recovery and Conversion of {sup 233}UF{sub 6} Chemisorbed in NaF Traps from the Molten Salt Reactor Remediation Project

    SciTech Connect

    Cul, Guillermo D. del; Icenhour, Alan S.; Simmons, Darrell W. [Oak Ridge National Laboratory (United States)

    2001-10-15

    The Molten Salt Reactor Experiment (MSRE) site at Oak Ridge National Laboratory is being cleaned up and remediated. The removal of {approx}37 kg of fissile {sup 233}U is the main activity. Of that inventory, {approx}23 kg has already been removed as UF{sub 6} from the piping system and chemisorbed in 25 NaF traps. This material is in temporary storage while it awaits conversion to a stable oxide. The planned recovery of {approx}11 kg of uranium from the fuel salt will generate another 15 to 19 NaF traps. The remaining 2 to 3 kg of uranium are present in activated charcoal beds, which are also scheduled to be removed from the reactor site. Since all of these materials (NaF traps and the uranium-laden charcoal) are not suitable for long-term storage, they will be converted to a uranium oxide (U{sub 3}O{sub 8}), which is suitable for long-term storage.The conversion of the MSRE material into an oxide presents unique problems, such as criticality concerns, a large radiation field caused by the daughters of {sup 232}U (an impurity isotope in the {sup 233}U), and the possible spread of the high-radiation field from the release of {sup 220}Rn gas. To overcome these problems, a novel process was conceived and developed. This process was specially tailored for providing remote operations inside a hot cell while maintaining full containment at all times to avoid the spread of contamination. This process satisfies criticality concerns, maximizes the recovery of uranium, minimizes any radiation exposure to operators, and keeps waste disposal to a minimum.

  7. Mechanism of Radial Redistribution of Energetic Trapped Ions Due to m=2/n=1 Internal Reconnection in Joint European Torus Shear Optimized Plasmas

    SciTech Connect

    N.N. Gorelenkov; A. Gondhalekar; A.A. Korotkov; S.E. Sharapov; D. Testa; and Contributors to the EFDA-JET Workprogramme

    2002-01-18

    Internal radial redistribution of MeV energy ICRF-driven hydrogen minority ions was inferred from neutral particle analyzer measurements during large amplitude MHD activity leading to internal reconnection in Shear Optimized plasmas in the Joint European Torus (JET). A theory is developed for energetic ion redistribution during a reconnection driven by an m=2/n=1 internal kink mode. Plasma motion during reconnection generates an electric field which can change the energy and radial position of the energetic ions. The magnitude of ion energy change depends on the value of the safety factor at the plasma core from which the energetic ions are redistributed. A relation is found for corresponding change in canonical momentum. P(subscript phi), which leads to radial displacement of the ions. The model yields distinctive new features of energetic ion redistribution under such conditions. Predicted characteristics of ion redistribution are compared with the NPA measurements, and good correlation is found. Sometimes fast ions were transported to the plasma edge due to interaction with a long-lived magnetic island which developed after the reconnection and had chirping frequency in the laboratory frame. Convection of resonant ions trapped in a radially moving phase-space island is modeled to understand the physics of such events.

  8. Optical trapping of dielectric nanoparticles in resonant cavities

    SciTech Connect

    Hu Juejun [Microphotonics Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716 (United States); Lin Shiyun; Crozier, Kenneth [School of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts 02138 (United States); Kimerling, Lionel C. [Microphotonics Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2010-11-15

    We theoretically investigate the opto-mechanical interactions between a dielectric nanoparticle and the resonantly enhanced optical field inside a high Q, small-mode-volume optical cavity. We develop an analytical method based on open system analysis to account for the resonant perturbation due to particle introduction and predict trapping potential in good agreement with three-dimensional (3D) finite-difference time-domain (FDTD) numerical simulations. Strong size-dependent trapping dynamics distinctly different from free-space optical tweezers arise as a consequence of the finite cavity perturbation. We illustrate single nanoparticle trapping from an ensemble of monodispersed particles based on size-dependent trapping dynamics. We further discover that the failure of the conventional dipole approximation in the case of resonant cavity trapping originates from a new perturbation interaction mechanism between trapped particles and spatially localized photons.

  9. Trapping of strangelets in the geomagnetic field

    SciTech Connect

    Paulucci, L.; Horvath, J. E.; Medina-Tanco, G. A. [Instituto de Fisica-Universidade de Sao Paulo, Rua do Matao, Travessa R, 187, 05508-090, Cidade Universitaria, Sao Paulo SP (Brazil); Instituto de Astronomia, Geofisica e Ciencias Atmosfericas-Universidade de Sao Paulo, Rua do Matao, 1226, 05508-900, Cidade Universitaria, Sao Paulo SP (Brazil); Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico A.P. 70-543, C.U. Mexico D.F. (Mexico)

    2008-02-15

    Strangelets arriving from the interstellar medium are an interesting target for experiments searching for evidence of this hypothetical state of hadronic matter. We entertain the possibility of a trapped strangelet population, quite analogous to ordinary nuclei and electron belts. For a population of strangelets to be trapped by the geomagnetic field, these incoming particles would have to fulfill certain conditions, namely, having magnetic rigidities above the geomagnetic cutoff and below a certain threshold for adiabatic motion to hold. We show in this work that, for fully ionized strangelets, there is a narrow window for stable trapping. An estimate of the stationary population is presented and the dominant loss mechanisms discussed. It is shown that the population would be substantially enhanced with respect to the interstellar medium flux (up to 2 orders of magnitude) due to quasistable trapping.

  10. Focused plasmonic trapping of metallic particles

    PubMed Central

    Min, Changjun; Shen, Zhe; Shen, Junfeng; Zhang, Yuquan; Fang, Hui; Yuan, Guanghui; Du, Luping; Zhu, Siwei; Lei, Ting; Yuan, Xiaocong

    2013-01-01

    Scattering forces in focused light beams push away metallic particles. Thus, trapping metallic particles with conventional optical tweezers, especially those of Mie particle size, is difficult. Here we investigate a mechanism by which metallic particles are attracted and trapped by plasmonic tweezers when surface plasmons are excited and focused by a radially polarized beam in a high-numerical-aperture microscopic configuration. This contrasts the repulsion exerted in optical tweezers with the same configuration. We believe that different types of forces exerted on particles are responsible for this contrary trapping behaviour. Further, trapping with plasmonic tweezers is found not to be due to a gradient force balancing an opposing scattering force but results from the sum of both gradient and scattering forces acting in the same direction established by the strong coupling between the metallic particle and the highly focused plasmonic field. Theoretical analysis and simulations yield good agreement with experimental results. PMID:24305554

  11. Trapped Electron Precession Shear Induced Fluctuation Decorrelation

    SciTech Connect

    T.S. Hahm; P.H. Diamond; E.-J. Kim

    2002-07-29

    We consider the effects of trapped electron precession shear on the microturbulence. In a similar way the strong E x B shear reduces the radial correlation length of ambient fluctuations, the radial variation of the trapped electron precession frequency can reduce the radial correlation length of fluctuations associated with trapped electrons. In reversed shear plasmas, with the explicit dependence of the trapped electron precession shearing rate on B(subscript)theta, the sharp radial gradient of T(subscript)e due to local electron heating inside qmin can make the precession shearing mechanism more effective, and reduce the electron thermal transport constructing a positive feedback loop for the T(subscript)e barrier formation.

  12. High spatiotemporal resolution imaging of mechanical processes in live cells using T-shaped cantilevers

    NASA Astrophysics Data System (ADS)

    Mandriota, Nicola; Sahin, Ozgur

    2014-03-01

    Mechanical properties of cells are paramount regulators of a plethora of physiological processes, such as cell adhesion, motility and proliferation. Yet, their knowledge is currently hampered by the lack of techniques with sufficient spatiotemporal resolution to monitor the dynamics of such biological processes. We introduce an atomic force microscopy-based imaging platform based on newly-designed cantilevers with increased force sensitivity, while minimizing viscous drag. This allows us to uncover mechanical properties of a wide variety of living cells - including fibroblasts, neurons and Human Umbilical Vein Endothelial Cells - with an unprecedented spatiotemporal resolution. Our mechanical maps approach 50nm resolution and monitor cellular features within a minute's timescale. To identify the counterparts of our mechanical maps' features we perform simultaneous fluorescence microscopy and recognize cytoskeletal elements as the main molecular contributors of cellular stiffness at the nanoscale. Furthermore, the enhanced resolution and speed of our method allows the recognition of dynamic changes in the mechanics of fine cellular structures, which occurred independently of changes within optical images of fluorescently-labeled actin.

  13. Microstructure, Mechanical and Corrosion Properties of Friction Stir-Processed AISI D2 Tool Steel

    NASA Astrophysics Data System (ADS)

    Yasavol, Noushin; Jafari, Hassan

    2015-05-01

    In this study, AISI D2 tool steel underwent friction stir processing (FSP). The microstructure, mechanical properties, and corrosion resistance of the FSPed materials were then evaluated. A flat WC-Co tool was used; the rotation rate of the tool varied from 400 to 800 rpm, and the travel speed was maintained constant at 385 mm/s during the process. FSP improved mechanical properties and produced ultrafine-grained surface layers in the tool steel. Mechanical properties improvement is attributed to the homogenous distribution of two types of fine (0.2-0.3 ?m) and coarse (1.6 ?m) carbides in duplex ferrite-martensite matrix. In addition to the refinement of the carbides, the homogenous dispersion of the particles was found to be more effective in enhancing mechanical properties at 500 rpm tool rotation rate. The improved corrosion resistance was observed and is attributed to the volume fraction of low-angle grain boundaries produced after friction stir process of the AISI D2 steel.

  14. Interaction of thermal and mechanical processes in steep permafrost rock walls: A conceptual approach

    NASA Astrophysics Data System (ADS)

    Draebing, D.; Krautblatter, M.; Dikau, R.

    2014-12-01

    Degradation of permafrost rock wall decreases stability and can initiate rock slope instability of all magnitudes. Rock instability is controlled by the balance of shear forces and shear resistances. The sensitivity of slope stability to warming results from a complex interplay of shear forces and resistances. Conductive, convective and advective heat transport processes act to warm, degrade and thaw permafrost in rock walls. On a seasonal scale, snow cover changes are a poorly understood key control of the timing and extent of thawing and permafrost degradation. We identified two potential critical time windows where shear forces might exceed shear resistances of the rock. In early summer combined hydrostatic and cryostatic pressure can cause a peak in shear force exceeding high frozen shear resistance and in autumn fast increasing shear forces can exceed slower increasing shear resistance. On a multiannual system scale, shear resistances change from predominantly rock-mechanically to ice-mechanically controlled. Progressive rock bridge failure results in an increase of sensitivity to warming. Climate change alters snow cover and duration and, hereby, thermal and mechanical processes in the rock wall. Amplified thawing of permafrost will result in higher rock slope instability and rock fall activity. We present a holistic conceptual approach connecting thermal and mechanical processes, validate parts of the model with geophysical and kinematic data and develop future scenarios to enhance understanding on system scale.

  15. Evaluation of a post-processing approach for multiscale analysis of biphasic mechanics of chondrocytes.

    PubMed

    Sibole, Scott C; Maas, Steve; Halloran, Jason P; Weiss, Jeffrey A; Erdemir, Ahmet

    2013-10-01

    Understanding the mechanical behaviour of chondrocytes as a result of cartilage tissue mechanics has significant implications for both evaluation of mechanobiological function and to elaborate on damage mechanisms. A common procedure for prediction of chondrocyte mechanics (and of cell mechanics in general) relies on a computational post-processing approach where tissue-level deformations drive cell-level models. Potential loss of information in this numerical coupling approach may cause erroneous cellular-scale results, particularly during multiphysics analysis of cartilage. The goal of this study was to evaluate the capacity of first- and second-order data passing to predict chondrocyte mechanics by analysing cartilage deformations obtained for varying complexity of loading scenarios. A tissue-scale model with a sub-region incorporating representation of chondron size and distribution served as control. The post-processing approach first required solution of a homogeneous tissue-level model, results of which were used to drive a separate cell-level model (same characteristics as the sub-region of control model). The first-order data passing appeared to be adequate for simplified loading of the cartilage and for a subset of cell deformation metrics, for example, change in aspect ratio. The second-order data passing scheme was more accurate, particularly when asymmetric permeability of the tissue boundaries was considered. Yet, the method exhibited limitations for predictions of instantaneous metrics related to the fluid phase, for example, mass exchange rate. Nonetheless, employing higher order data exchange schemes may be necessary to understand the biphasic mechanics of cells under lifelike tissue loading states for the whole time history of the simulation. PMID:23809004

  16. A new perspective on the functioning of the brain and the mechanisms behind conscious processes.

    PubMed

    Keppler, Joachim

    2013-01-01

    An essential prerequisite for the development of a theory of consciousness is the clarification of the fundamental mechanisms underlying conscious processes. In this article I present an approach that sheds new light on these mechanisms. This approach builds on stochastic electrodynamics (SED), a promising theoretical framework that provides a deeper understanding of quantum systems and reveals the origin of quantum phenomena. I outline the most important concepts and findings of SED and interpret the neurophysiological body of evidence in the context of these findings, indicating that the functioning of the brain rests upon exactly the same principles that are characteristic for quantum systems. On this basis, I construct a new hypothesis on the mechanisms behind conscious processes and discuss the new perspectives this hypothesis opens up for consciousness research. In particular, it offers the possibility of elucidating the relationship between brain and consciousness, of specifying the connection between consciousness and information, and of answering the question of what distinguishes conscious processes from unconscious processes. PMID:23641229

  17. A new perspective on the functioning of the brain and the mechanisms behind conscious processes

    PubMed Central

    Keppler, Joachim

    2013-01-01

    An essential prerequisite for the development of a theory of consciousness is the clarification of the fundamental mechanisms underlying conscious processes. In this article I present an approach that sheds new light on these mechanisms. This approach builds on stochastic electrodynamics (SED), a promising theoretical framework that provides a deeper understanding of quantum systems and reveals the origin of quantum phenomena. I outline the most important concepts and findings of SED and interpret the neurophysiological body of evidence in the context of these findings, indicating that the functioning of the brain rests upon exactly the same principles that are characteristic for quantum systems. On this basis, I construct a new hypothesis on the mechanisms behind conscious processes and discuss the new perspectives this hypothesis opens up for consciousness research. In particular, it offers the possibility of elucidating the relationship between brain and consciousness, of specifying the connection between consciousness and information, and of answering the question of what distinguishes conscious processes from unconscious processes. PMID:23641229

  18. In situ observation of penetration process in silica aerogel: Deceleration mechanism of hard spherical projectiles

    NASA Astrophysics Data System (ADS)

    Niimi, Rei; Kadono, Toshihiko; Arakawa, Masahiko; Yasui, Minami; Dohi, Koji; Nakamura, Akiko M.; Iida, Yosuke; Tsuchiyama, Akira

    2011-02-01

    A large number of cometary dust particles were captured with low-density silica aerogels by NASA's Stardust Mission. Knowledge of the details of the capture mechanism of hypervelocity particles in silica aerogel is needed in order to correctly derive the original particle features from impact tracks. However, the mechanism has not been fully understood yet. We shot hard spherical projectiles of several different materials into silica aerogel of density 60 mg cm -3 and observed their penetration processes using an image converter or a high-speed video camera. In order to observe the deceleration of projectiles clearly, we carried out impact experiments at two velocity ranges; ˜4 km s -1 and ˜200 m s -1. From the movies we took, it was indicated that the projectiles were decelerated by hydrodynamic force which was proportional to v2 ( v: projectile velocity) during the faster penetration process (˜4 km s -1) and they were merely overcoming the aerogel crushing strength during the slower penetration process (˜200 m s -1). We applied these deceleration mechanisms for whole capture process to calculate the track length. Our model well explains the track length in the experimental data set by Burchell et al. (Burchell, M.J., Creighton, J.A., Cole, M.J., Mann, J., Kearsley, A.T. [2001]. Meteorit. Planet. Sci. 36, 209-221).

  19. Processing Conditions Affecting Grain Size and Mechanical Properties in Nanocomposites Produced via Cold Spray

    NASA Astrophysics Data System (ADS)

    Cavaliere, P.; Perrone, A.; Silvello, A.

    2014-10-01

    Cold spray is a coating technology based on aerodynamics and high-speed impact dynamics. In this process, spray particles (usually 1-50 ?m in diameter) are accelerated to a high velocity (typically 300-1200 m/s) by a high-speed gas (pre-heated air, nitrogen, or helium) flow that is generated through a convergent-divergent de Laval-type nozzle. A coating is formed through the intensive plastic deformation of particles impacting on a substrate at a temperature below the melting point of the spray material. In the present paper the main processing parameters affecting the microstructural and mechanical behavior of metal-metal cold spray deposits are described. The effect of process parameters on grain refinement and mechanical properties were analyzed for composite particles of Al-Al2O3, Ni-BN, Cu-Al2O3, and Co-SiC. The properties of the formed nanocomposites were compared with those of the parent materials sprayed under the same conditions. The process conditions, leading to a strong grain refinement with an acceptable level of the deposit mechanical properties such as porosity and adhesion strength, are discussed.

  20. Influence of pore morphology and topology on capillary trapping in geological carbon dioxide sequestration

    NASA Astrophysics Data System (ADS)

    Andersson, L.; Harper, E.; Herring, A. L.; Wildenschild, D.

    2012-12-01

    Current carbon capture and storage (CCS) techniques could reduce the release of anthropogenic CO2 into the atmosphere by subsurface sequestration of CO2 in saline aquifers. In geological storage CO2 is injected into deep underground porous formations where CO2 is in the supercritical state. Deep saline aquifers are particularly attractive because of their abundance and potentially large storage volumes. Despite very broad research efforts there are still substantial uncertainties related to the effectiveness of the trapping, dissolution, and precipitation processes controlling the permanent storage of CO2. After injection of CO2 the saline water (brine) will imbibe back and reoccupy the pore space as the CO2 moves upwards, trapping a large part of the CO2. This trapping mechanism is known as capillary trapping and occurs as isolated CO2 bubbles are locked in the brine inside the pores of the porous rock. The large-scale movement of CO2 within the brine is thereby prevented. This mechanism thus constitutes an important storage mechanism after the CO2 injection until the subsequent dissolution trapping and precipitation of carbonate mineral. The capillary trapping of CO2 depends largely on the shape and interconnectivity of the pore space and it is therefore important to study the influence of pore scale morphology and topology to understand and optimize large scale capillary trapping. We use a high pressure set-up, designed for supercritical CO2 conditions, with a flow cell compatible with synchrotron-based X-ray computed micro-tomography (CMT) to generate high-resolution images to study capillary trapping. We use sintered glass bead columns as an approximation for unconsolidated reservoir systems. The smooth surface glass bead data allow us to separate the chemistry and surface roughness effects of the porous medium from the effect of the morphology and topology on the capillary trapping. We will relate these aspects of the pore space to the distribution of the fluids (wetting and non-wetting) and initial and residual non-wetting phase saturations. Potential wettability alteration due to exposure of the beads to supercritical CO2 is also explored by comparing high-pressure and low-pressure experimental results.

  1. Search for trapped antihydrogen

    NASA Astrophysics Data System (ADS)

    Andresen, G. B.; Ashkezari, M. D.; Baquero-Ruiz, M.; Bertsche, W.; Bowe, P. D.; Bray, C. C.; Butler, E.; 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.; Jørgensen, L. V.; Kurchaninov, L.; Lambo, R.; Madsen, N.; Menary, S.; Nolan, P.; Olchanski, K.; Olin, A.; Povilus, A.; Pusa, P.; Robicheaux, F.; Sarid, E.; Seif El Nasr, S.; Silveira, D. M.; So, C.; Storey, J. W.; Thompson, R. I.; van der Werf, D. P.; Wilding, D.; Wurtele, J. S.; Yamazaki, Y.; Alpha Collaboration

    2011-01-01

    We present the results of an experiment to search for trapped antihydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator. Sensitive diagnostics of the temperatures, sizes, and densities of the trapped antiproton and positron plasmas have been developed, which in turn permitted development of techniques to precisely and reproducibly control the initial experimental parameters. The use of a position-sensitive annihilation vertex detector, together with the capability of controllably quenching the superconducting magnetic minimum trap, enabled us to carry out a high-sensitivity and low-background search for trapped synthesised antihydrogen atoms. We aim to identify the annihilations of antihydrogen atoms held for at least 130 ms in the trap before being released over ?30 ms. After a three-week experimental run in 2009 involving mixing of 10 7 antiprotons with 1.3×10 positrons to produce 6×10 antihydrogen atoms, we have identified six antiproton annihilation events that are consistent with the release of trapped antihydrogen. The cosmic ray background, estimated to contribute 0.14 counts, is incompatible with this observation at a significance of 5.6 sigma. Extensive simulations predict that an alternative source of annihilations, the escape of mirror-trapped antiprotons, is highly unlikely, though this possibility has not yet been ruled out experimentally.

  2. Nuclear Physics with trapped

    E-print Network

    Boas, Harold P.

    Outline · Scope and applications of nuclear physics precision frontier compliments LHC properties and therapeutic medicine · "Cool" tools ­ atom traps probing fundamental symmetries (ion traps) trace analysis The precision frontier probes similar physics compared to colliders; is a complementary and important cross

  3. Search For Trapped Antihydrogen

    E-print Network

    Gorm B. Andresen; Mohammad D. Ashkezari; Marcelo Baquero-Ruiz; William Bertsche; Paul D. Bowe; Crystal C. Bray; Eoin Butler; Claudio L. Cesar; Steven Chapman; Michael Charlton; Joel Fajans; Tim Friesen; Makoto C. Fujiwara; David R. Gill; Jeffrey S. Hangst; Walter N. Hardy; Ryugo S. Hayano; Michael E. Hayden; Andrew J. Humphries; Richard Hydomako; Svante Jonsell; Lars V. J\\orgensen; Lenoid Kurchaninov; Ricardo Lambo; Niels Madsen; Scott Menary; Paul Nolan; Konstantin Olchanski; Art Olin; Alexander Povilus; Petteri Pusa; Francis Robicheaux; Eli Sarid; Sarah Seif El Nasr; Daniel M. Silveira; Chukman So; James W. Storey; Robert I. Thompson; Dirk P. van der Werf; Dean Wilding; Jonathan S. Wurtele; Yasunori Yamazaki

    2010-12-18

    We present the results of an experiment to search for trapped antihydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator. Sensitive diagnostics of the temperatures, sizes, and densities of the trapped antiproton and positron plasmas have been developed, which in turn permitted development of techniques to precisely and reproducibly control the initial experimental parameters. The use of a position-sensitive annihilation vertex detector, together with the capability of controllably quenching the superconducting magnetic minimum trap, enabled us to carry out a high-sensitivity and low-background search for trapped synthesised antihydrogen atoms. We aim to identify the annihilations of antihydrogen atoms held for at least 130 ms in the trap before being released over ~30 ms. After a three-week experimental run in 2009 involving mixing of 10^7 antiprotons with 1.3 10^9 positrons to produce 6 10^5 antihydrogen atoms, we have identified six antiproton annihilation events that are consistent with the release of trapped antihydrogen. The cosmic ray background, estimated to contribute 0.14 counts, is incompatible with this observation at a significance of 5.6 sigma. Extensive simulations predict that an alternative source of annihilations, the escape of mirror-trapped antiprotons, is highly unlikely, though this possibility has not yet been ruled out experimentally.

  4. Buffer strips trap contaminants

    E-print Network

    Nebraska-Lincoln, University of

    ideal width for riparian buffer strips in Midwest. They trap sediment, nutrients and pesticides. That maater Buffer strips trap contaminants Three research and demonstration projects seek to determine kes riparian buffer strips a valuable tool in preventing nonpo int sour ce pollution, according

  5. Mechanical properties and production quality of hand-layup and vacuum infusion processed hybrid composite materials for GFRP marine structures

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Young; Shim, Chun Sik; Sturtevant, Caleb; Kim, Dave (Dae-Wook); Song, Ha Cheol

    2014-09-01

    Glass Fiber Reinforced Plastic (GFRP) structures are primarily manufactured using hand lay-up or vacuum infusion techniques, which are cost-effective for the construction of marine vessels. This paper aims to investigate the mechanical properties and failure mechanisms of the hybrid GFRP composites, formed by applying the hand lay-up processed exterior and the vacuum infusion processed interior layups, providing benefits for structural performance and ease of manufacturing. The hybrid GFRP composites contain one, two, and three vacuum infusion processed layer sets with consistent sets of hand lay-up processed layers. Mechanical properties assessed in this study include tensile, compressive and in-plane shear properties. Hybrid composites with three sets of vacuum infusion layers showed the highest tensile mechanical properties while those with two sets had the highest mechanical properties in compression. The batch homogeneity, for the GFRP fabrication processes, is evaluated using the experimentally obtained mechanical properties

  6. 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 hydrodynamic radius bovine serum albumin proteins8. In this work, the experimental configuration used for nanoparticle trapping is outlined. First, we detail the assembly of the trapping setup which is based on a Thorlabs Optical Tweezer Kit. Next, we explain the nanofabrication procedure of the double-nanohole in a metal film, the fabrication of the microfluidic chamber and the sample preparation. Finally, we detail the data acquisition procedure and provide typical results for trapping 20 nm polystyrene nanospheres. PMID:23354173

  7. Deuterium trapping in tungsten

    NASA Astrophysics Data System (ADS)

    Poon, Michael

    Tungsten is one of the primary material candidates being investigated for use in the first-wall of a magnetic confinement fusion reactor. An ion accelerator was used to simulate the type of ion interaction that may occur at a plasma-facing material. Thermal desorption spectroscopy (TDS) was the primary tool used to analyze the effects of the irradiation. Secondary ion mass spectroscopy (SIMS) was used to determine the distribution of trapped D in the tungsten specimen. The tritium migration analysis program (TMAP) was used to simulate thermal desorption profiles from the D depth distributions. Fitting of the simulated thermal desorption profiles with the measured TDS results provided values of the D trap energies. Deuterium trapping in single crystal tungsten was studied as a function of the incident ion fluence, ion flux, irradiation temperature, irradiation history, and surface impurity levels during irradiation. The results show that deuterium was trapped at vacancies and voids. Two deuterium atoms could be trapped at a tungsten vacancy, with trapping energies of 1.4 eV and 1.2 eV for the first and second D atoms, respectively. In a tungsten void, D is trapped as atoms adsorbed on the inner walls of the void with a trap energy of 2.1 eV, or as D2 molecules inside the void with a trap energy of 1.2 eV. Deuterium trapping in polycrystalline tungsten was also studied as a function of the incident fluence, irradiation temperature, and irradiation history. Deuterium trapping in polycrystalline tungsten also occurs primarily at vacancies and voids with the same trap energies as in single crystal tungsten; however, the presence of grain boundaries promotes the formation of large surface blisters with high fluence irradiations at 500 K. In general, D trapping is greater in polycrystalline tungsten than in single crystal tungsten. To simulate mixed materials comprising of carbon (C) and tungsten, tungsten specimens were pre-irradiated with carbon ions prior to D irradiation. Deuterium trapping could be characterized by three regimes: (i) enhanced D retention in a graphitic film formed by the C+ irradiation; (ii) decreased D retention in a modified tungsten-carbon layer; and (iii) D retention in pure tungsten.

  8. Optically programmable excitonic traps.

    PubMed

    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

  9. Assessing the similarity of mechanisms in motion and color processing for synchronization of visual pathways

    NASA Astrophysics Data System (ADS)

    Rising, Hawley K., III

    1997-06-01

    Given the great diversity of pathways into which the visual system signal splits after arriving at area V1, many researchers have proposed solutions to the 'binding problem' of reunifying the information after specialized processing. Most solutions require pathways to maintain synchrony and share information, which in turn requires some similarity of mechanisms and/or the spaces in which they operate. We examine the extent to which such similarity can occur between motion and color processing pathways, by using a multiple stage motion detection algorithm for processing color change. We first review the motion algorithm chosen, then we present a model for certain changes in hue, discuss the possible uses for such processes in the visual system, and present results of applying this model to both motion and color in this manner.

  10. Controlled Thermal-Mechanical Processing of Tubes and Pipes for Enhanced Manufacturing and Performance

    SciTech Connect

    Kolarik, Robert V.

    2005-11-11

    The Alloy Steel Business of The Timken Company won an award for the controlled thermo-mechanical processing (CTMP) project and assembled a strong international public/private partnership to execute the project. The premise of the CTMP work was to combine Timken's product understanding with its process expertise and knowledge of metallurgical and deformation fundamentals developed during the project to build a predictive process design capability. The CTMP effort succeeded in delivering a pc-based capability in the tube optimization model, with a virtual pilot plant (VPP) feature to represent the desired tube making process to predict the resultant microstructure tailored for the desired application. Additional tasks included a system for direct, online measurement of grain size and demonstration of application of CTMP via robotically enhanced manufacturing.

  11. Panel report on coupled thermo-mechanical-hydro-chemical processes associated with a nuclear waste repository

    SciTech Connect

    Tsang, C.F.; Mangold, D.C. (eds.)

    1984-07-01

    Four basic physical processes, thermal, hydrological, mechanical and chemical, are likely to occur in 11 different types of coupling during the service life of an underground nuclear waste repository. A great number of coupled processes with various degrees of importance for geological repositories were identified and arranged into these 11 types. A qualitative description of these processes and a tentative evaluation of their significance and the degree of uncertainty in prediction is given. Suggestions for methods of investigation generally include, besides theoretical work, laboratory and large scale field testing. Great efforts of a multidisciplinary nature are needed to elucidate details of several coupled processes under different temperature conditions in different geological formations. It was suggested that by limiting the maximum temperature to 100{sup 0}C in the backfill and in the host rock during the whole service life of the repository the uncertainties in prediction of long-term repository behavior might be considerably reduced.

  12. Biosorption of malachite green by eggshells: mechanism identification and process optimization.

    PubMed

    Podstawczyk, Daria; Witek-Krowiak, Anna; Chojnacka, Katarzyna; Sadowski, Zygmunt

    2014-05-01

    In the present work, eggshells were used to remove a dye (malachite green) from wastewater. The study was focused on identification and describing the binding mechanism of the dye by eggshells in a biosorption process optimized by Response Surface Methodology based on the Box-Behnken Design. The mechanism of biosorption was determined by characterization of the biosorbent before and after biosorption using scanning electron microscopy, X-ray diffraction analysis, the Brunauer-Emmett-Teller isotherm method, Fourier transform infrared spectroscopy. The second-order polynomial equation and 3D response surface plots were used to quantitatively determine the relationships between dependent and independent variables. The obtained results suggested the mechanism of wastewater treatment that included physical adsorption, alkaline fading phenomenon and microprecipitation. The results of the present study showed that waste eggshells have the potential to be used as an inexpensive but effective biosorbent useful in wastewater treatment. PMID:24507580

  13. Switching mechanisms in flexible solution-processed TiO2 memristors

    NASA Astrophysics Data System (ADS)

    Tedesco, J. L.; Stephey, L.; Hernández-Mora, M.; Richter, C. A.; Gergel-Hackett, N.

    2012-08-01

    Memristors are emerging as unique electrical devices with potential applications in memory, reconfigurable logic and biologically inspired computing. Due to the novelty of these devices, the complete details of their switching mechanism is not yet well established. In this work, the switching mechanism of our solution-processed titanium dioxide-based memristor is investigated by studying how variations in the device area and film thickness affect electrical behavior and correlating these behavioral changes to proposed switching mechanisms. The conduction path of the switching is also investigated through electrical characterization of devices both before and after physically cutting the devices in half, as well as through infrared imaging of the devices during operation. The results suggest that the electrical behavior of these devices is dominated by a localized, charge-based phenomenon that exhibits a dependence on device area. Official contribution of the National Institute of Standards and Technology; not subject to copyright in the United States of America.

  14. Diverse mechanisms for spliceosome-mediated 3? end processing of telomerase RNA

    PubMed Central

    Kannan, Ram; Helston, Rachel M.; Dannebaum, Richard O.; Baumann, Peter

    2015-01-01

    The 3? end of Schizosaccharomyces pombe telomerase RNA (SpTER1) is generated by spliceosomal cleavage, a reaction that corresponds to the first step of splicing. The observation that the spliceosome functions in 3? end processing raised questions about the evolutionary origin and conservation of this mechanism. We now present data in support of spliceosomes generating 3? ends of telomerase RNAs in other fungi. Strikingly, the mechanistic basis for restricting spliceosomal splicing to the first transesterification reaction differs substantially among species. Unlike S. pombe, two other fission yeasts rely on hyperstabilization of the U6 snRNA—5? splice site interaction to impede the 2nd step of splicing. In contrast, a non-canonical 5? splice site blocks the second transesterification reaction in Aspergillus species. These results demonstrate a conserved role for spliceosomes functioning in 3? end processing. Divergent mechanisms of uncoupling the two steps of splicing argue for multiple origins of this pathway. PMID:25598145

  15. Effects of thermomechanical processing on the resulting mechanical properties of 6101 aluminum foam

    SciTech Connect

    Margevicius, R.W.; Stanek, P.W.; Jacobson, L.A.

    1998-12-01

    Porous materials represent a tremendous weight savings for light-weight structural applications. The fabrication path can play a critical role in the resulting properties. High porosity aluminum was fabricated in a number of ways. The starting material was a cast 6101 aluminum that had a relative density of 9.8%. The cast aluminum block was compressed by uniaxial, biaxial, and triaxial densification. Uniaxial compression was done at room temperature and 200 C. Biaxial compression was achieved by unidirectional rolling at room temperature and 200 C. Triaxial compression was done by cold isostatic pressing at 3.4, 6.7, and 34 MPa (0.5, 1.0, and 5.0 ksi). Metallography and mechanical test specimens were machines from the processed bars. The mechanical properties showed that the relative yield strength depended both on relative density and processing temperature.

  16. Trapping of radiation in plasmas

    SciTech Connect

    Riley, M.E.; Alford, W.J.

    1995-06-01

    The authors analyze the problem of radiation trapping (imprisonment) by the method of Holstein. The process is described by an integrodifferential equation which shows that the effective radiative decay rate of the system depends on the size and the shape of the active medium. Holstein obtains a global decay rate for a particular geometry by assuming that the radiating excited species evolves into a steady state spatial mode. The authors derive a new approximation for the trapped decay which has a space dependent decay rate and is easy to implement in a detailed computer simulation of a plasma confined within an arbitrary geometry. They analyze the line shapes that are relevant to a near-atmospheric-pressure mixture of He and Xe. This line-shape analysis can be utilized in either the Holstein formulae or the space-dependent decay approximation.

  17. Thermodynamic and fracture mechanical processes in the context of frost wedging in ice shelves

    NASA Astrophysics Data System (ADS)

    Plate, Carolin; Müller, Ralf; Humbert, Angelika; Gross, Dietmar

    2015-04-01

    Ice shelves, the link between ice shields or glaciers and the ocean are sensitive elements of the polar environment. The ongoing break up and disintegration of huge ice shelf parts or entire ice shelf demands for an explication of the underlying processes. The first analyses of crack growth and break up events in ice shelves date back to more than half a century. Nevertheless, the mechanisms that trigger and influence the collapse of whole ice shelf parts are not yet fully understood. Popular presumptions link ice shelf disintegration to surface meltwater and hydro fracturing, explaining break up events in warm polar seasons. Fracture events during colder seasons are possibly triggered by more complex mechanisms. A well-documented break up event at the Wilkins Ice Shelf bridge inspires the possibility of frost wedging as disintegration cause. The present study shows a two-dimensional thermo-dynamical model simulating the growth of an ice lid in a water-filled crevasse for measured surface temperatures. The influence of the crevasse geometry and the ice shelf temperature are shown. The resulting lid thickness is then used for the linear elastic fracture mechanical analysis. The maximum crack depth is estimated by comparing the computed stress intensity factors to critical values KIc obtained from literature. The thermodynamic as well as the fracture mechanical simulation are performed using the commercial finite element code COMSOL. The computation of KI follows in post processing routines in MATLAB exploiting the benefits of the concept of configurational forces.

  18. The influence of thermal-mechanical processing on residual stresses in titanium matrix composites

    Microsoft Academic Search

    P. Rangaswamy; M. A. M. Bourke; P. K. Wright; N. Jayaraman; E. Kartzmark; J. A. Roberts

    1997-01-01

    The effects of three distinct thermo-mechanical processes on the residual stress state in a uni-directionally reinforced SCS-6\\/Ti-6-2-4-2[0]6 titanium-alloy matrix composite were predicted using a finite element model. For comparison the residual stresses were measured using X-ray and neutron diffraction. Reductions in stress were predicted by the models and both experimental techniques recorded a reduction compared to the as-fabricated material. While

  19. Wear of aluminium-base materials processed by mechanical milling in air or ammonia

    Microsoft Academic Search

    Patricia Iglesias; Mar??a-Dolores Bermúdez; Francisco J. Carrión; Ginés Mart??nez-Nicolás; Enrique J. Herrera; José A. Rodriguez; Moisés Naranjo

    2003-01-01

    The tribological behaviour of mechanically alloyed (MA) aluminium-base materials has been studied as a function of processing methods. In particular, a new sintered MA aluminium material, milled under an ammonia atmosphere (MA Al-NH3) and consolidated by a single cycle of cold compaction and sintering, is compared with conventional MA aluminium (MA Al-air), milled in confined air and consolidated by a

  20. Improvement of mechanical properties of aluminum die casting alloy by multi-pass friction stir processing

    Microsoft Academic Search

    K. Nakata; Y. G. Kim; H. Fujii; T. Tsumura; T. Komazaki

    2006-01-01

    An improvement in the mechanical properties was accomplished due to the microstructural modification of an aluminum die casting alloy by multi-pass friction stir processing (MP-FSP), which is a solid-state microstructural modification technique using a frictional heat and stirring action. The hardness of the MP-FSP sample is about 20Hv higher than that of the base metal. The tensile strengths of the

  1. INFLUENCE OF THE WELDING PROCESS ON THE MECHANICAL PROPERTIES OF THE WELDED JOINT

    Microsoft Academic Search

    Branko Bauer; Slobodan Kralj

    Laser and TIG welding processes are suitable for welding of thin sheets. Welding of heat-treatable steels causes substantial increase of the hardness in the welded joint area. The increase of hardness does not necessarily have a negative influence on the mechanical properties of the welded joint. Butt welds of 2 mm thick heat-treatable steel sheets 25CrMo4 and 42CrMo4 were welded

  2. Novel electrolysis-ionized-water cleaning technique for the chemical-mechanical polishing (CMP) process

    Microsoft Academic Search

    H. Aoki; T. Nakajima; K. Kikuta; Y. Hayashi

    1994-01-01

    Recently, chemical-mechanical-polishing (CMP) technology has become more and more important as device packing-density has increased. This is because the CMP of interlayer dielectrics realizes global planarization resulting in multi-level interconnections with finer pitches. However, effective wafer surface cleaning for particles and contamination is needed because slurries with colloidal silica particles are used during the CMP processing. Though wafer cleaning by

  3. Processing of yttria stabilized zirconia reinforced with multi-walled carbon nanotubes with attractive mechanical properties

    Microsoft Academic Search

    Mehdi Mazaheri; Daniele Mari; Robert Schaller; Guillaume Bonnefont; Gilbert Fantozzi

    2011-01-01

    The improvement of the mechanical properties of carbon nanotube reinforced polycrystalline yttria-stabilized zirconia (CNT–YSZ) was questionable in earlier investigations due to several difficulties for processing of these composites. In the present article, the authors are proposing a successful technique for mixing pre-dispersed CNTs within YSZ particles followed by a fast spark plasma sintering at relatively low temperature, resulting in near

  4. Process for improving mechanical properties of epoxy resins by addition of cobalt ions

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St.clair, A. K. (inventors)

    1984-01-01

    A resin product useful as an adhesive, composite or casting resin is described as well as the process used in its preparation to improve its flexural strength mechanical property characteristics. Improved flexural strength is attained with little or no change in density, thermal stability or moisture resistance by chemically incorporating 1.2% to 10.6% by weight Co(3) ions in an epoxidized resin system.

  5. Multiscale Simulation of Thermo-mechanical Processes in Irradiated Fission-reactor Materials

    SciTech Connect

    El-Azab, Anter

    2012-05-28

    This report contains a summary of progress made on the subtask area on phase field model development for microstructure evolution in irradiated materials, which was a part of the Computational Materials Science Network (CMSN) project entitled: Multiscale Simulation of Thermo-mechanical Processes in Irradiated Fission-reactor Materials. The model problem chosen has been that of void nucleation and growth under irradiation conditions in single component systems.

  6. The mechanical response of a uranium-nobium alloy: a comparison of cast versus wrought processing

    Microsoft Academic Search

    Carl M Cady; Gray; George T; Ellen K Cerreta; Robert M Aikin; Shuh-Rong Chen; Carl P Trujillo; Mike F Lopez; Deniese R Korzekwa; Ann M Kelly

    2009-01-01

    A rigorous experimentation and validation program is being undertaken to create constitutive models that elucidate the fundamental mechanisms controlling plasticity in uranium-6 wt.% niobium alloys (U-6Nb). The first, 'wrought', material produced by processing a cast ingot I'ia forging and forming into plate was studied. The second material investigated is a direct cast U-6Nb alloy. The purpose of the investigation is

  7. Mechanical properties of WC–10Co cemented carbides sintered from nanocrystalline spray conversion processed powders

    Microsoft Academic Search

    Seung I. Cha; Soon H. Hong; Gook H. Ha; Byung K. Kim

    2001-01-01

    Mechanical properties and microstructures of nanocrystalline WC–10Co cemented carbides were investigated. The nanocrystalline WC–10Co cemented carbide powders were manufactured by reduction and carbonization of the nanocrystalline precursor powders which were prepared by spray drying process of solution containing ammonia meta-tungstate (AMT) and cobalt nitrate. The WC powders were about 100 nm in diameter mixed homogeneously with Co binder phase and

  8. Mechanisms of Direct Radiation Damage in DNA, Based on a Study of the Yields of Base Damage, Deoxyribose Damage, and Trapped Radicals in d(GCACGCGTGC)2

    PubMed Central

    Swarts, Steven G.; Gilbert, David C.; Sharma, Kiran K.; Razskazovskiy, Yuriy; Purkayastha, Shubhadeep; Naumenko, Katerina A.; Bernhard, William A.

    2009-01-01

    Dose–response curves were measured for the formation of direct-type DNA products in X-irradiated d(GCACGCGTGC)2 prepared as dry films and as crystalline powders. Damage to deoxyribose (dRib) was assessed by HPLC measurements of strand break products containing 3? or 5? terminal phosphate and free base release. Base damage was measured using GC/MS after acid hydrolysis and trimethylsilylation. The yield of trappable radicals was measured at 4 K by EPR of films X-irradiated at 4 K. With exception of those used for EPR, all samples were X-irradiated at room temperature. There was no measurable difference between working under oxygen or under nitrogen. The chemical yields (in units of nmol/J) for trapped radicals, free base release, 8-oxoGua, 8-oxoAde, diHUra and diHThy were Gtotal(fr) = 618 ± 60, G(fbr) = 93 ± 8, G(8-oxoGua) = 111 ± 62, G(8-oxoAde) = 4 ± 3, G(diHUra) = 127 ± 160, and G(diHThy) = 39 ± 60, respectively. The yields were determined and the dose–response curves explained by a mechanistic model consisting of three reaction pathways: (1) trappable-radical single-track, (2) trappable-radical multiple-track, and (3) molecular. If the base content is projected from the decamer’s GC:AT ratio of 4:1 to a ratio of 1:1, the percentage of the total measured damage (349 nmol/J) would partition as follows: 20 ± 16% 8-oxoGua, 3 ± 3% 8-oxoAde, 28 ± 46% diHThy, 23 ± 32% diHUra, and 27 ± 17% dRib damage. With a cautionary note regarding large standard deviations, the projected yield of total damage is higher in CG-rich DNA because C combined with G is more prone to damage than A combined with T, the ratio of base damage to deoxyribose damage is ~3:1, the yield of diHUra is comparable to the yield of diHThy, and the yield of 8-oxoAde is not negligible. While the quantity and quality of the data fall short of proving the hypothesized model, the model provides an explanation for the dose–response curves of the more prevalent end products and provides a means of measuring their chemical yields, i.e., their rate of formation at zero dose. Therefore, we believe that this comprehensive analytical approach, combined with the mechanistic model, will prove important in predicting risk due to exposure to low doses and low dose rates of ionizing radiation. PMID:17705640

  9. Process mechanics and surface integrity of low plasticity burnishing of SE508 nitinol alloy

    NASA Astrophysics Data System (ADS)

    McKinney, John Ellis, Jr.

    Superelastic Nitinol and shape memory alloys have attracted growing attentions over the recent years in the areas of biomedical and aerospace applications. Surface integrity of Nitinol devices by various fabrication processes is critical for their functionality and performance. Low plasticity burnishing (LPB) is a surface enhancement process to improve surface integrity due to its unique capability to plastically deform material in the deep subsurface on the order of a 500-1000microm. This thesis focuses on the dynamic mechanical behavior of SE508 Nitinol (NiTi) alloy and process mechanics and surface integrity by ball burnishing of the material. The stress-strain behaviors of SE508 NiTi alloy at quasi-static and high strain rates were experimentally determined using a series of compression testing. Then, the experimentally determined stress-strain behavior was used in correlation with Hertzian theory of contact mechanics in ball burnishing of the material. It was found that quasi-static compressive stress-strain behavior correlates well with Hertzian peak pressure. This serves as a basis to select burnishing loads. The effects of LPB parameters, i.e. burnishing pressure, feed, speed, number of path, and pattern on surface integrity characteristics such as surface topography, roughness, microhardness, and microstructure are investigated.

  10. Effect of Processing Parameters on the Mechanical Properties of Interstitial Free Steel Subjected to Friction Stir Processing

    NASA Astrophysics Data System (ADS)

    Chabok, A.; Dehghani, K.

    2013-05-01

    In the present work, the effect of friction stir processing parameters on the mechanical properties of an interstitial free steel was studied. Four rotating speeds (800, 1250, 1600, 2000 rpm) and two traverse speeds (31.5 and 63 mm/min) were employed. On both sides of specimens, a nanograin layer with the thickness and nanograins of 150 ?m and 50-100 nm were formed, respectively. For the specimen processed at rotating speed of 1600 rpm and the traverse speed of 31.5 mm/min, the maximum strength was achieved, which was about 80% increase in the strength comparing to that of base material. For constant traverse speed, the increase in the rotation speed from 800 to 1600 rpm led to a decrease in uniform and total elongation of friction stir processed samples. By contrast, when the rotating speed exceeded 1600 rpm, the uniform and total elongation was increased again, while there was a drop in strength. The results of microhardness indicate more than threefold increase in the hardness of the stirred zone comparing to that of base material.

  11. Scaling the ion trap quantum processor.

    PubMed

    Monroe, C; Kim, J

    2013-03-01

    Trapped atomic ions are standards for quantum information processing, serving as quantum memories, hosts of quantum gates in quantum computers and simulators, and nodes of quantum communication networks. Quantum bits based on trapped ions enjoy a rare combination of attributes: They have exquisite coherence properties, they can be prepared and measured with nearly 100% efficiency, and they are readily entangled with each other through the Coulomb interaction or remote photonic interconnects. The outstanding challenge is the scaling of trapped ions to hundreds or thousands of qubits and beyond, at which scale quantum processors can outperform their classical counterparts in certain applications. We review the latest progress and prospects in that effort, with the promise of advanced architectures and new technologies, such as microfabricated ion traps and integrated photonics. PMID:23471398

  12. Evaluation of a Post-Processing Approach for Multiscale Analysis of Biphasic Mechanics of Chondrocytes

    PubMed Central

    Sibole, Scott C.; Maas, Steve; Halloran, Jason P.; Weiss, Jeffrey A.; Erdemir, Ahmet

    2014-01-01

    Understanding the mechanical behavior of chondrocytes as a result of cartilage tissue mechanics has significant implications for both evaluation of mechanobiological function and to elaborate on damage mechanisms. A common procedure for prediction of chondrocyte mechanics (and of cell mechanics in general) relies on a computational post-processing approach where tissue level deformations drive cell level models. Potential loss of information in this numerical coupling approach may cause erroneous cellular scale results, particularly during multiphysics analysis of cartilage. The goal of this study was to evaluate the capacity of 1st and 2nd order data passing to predict chondrocyte mechanics by analyzing cartilage deformations obtained for varying complexity of loading scenarios. A tissue scale model with a sub-region incorporating representation of chondron size and distribution served as control. The postprocessing approach first required solution of a homogeneous tissue level model, results of which were used to drive a separate cell level model (same characteristics as the subregion of control model). The 1st data passing appeared to be adequate for simplified loading of the cartilage and for a subset of cell deformation metrics, e.g., change in aspect ratio. The 2nd order data passing scheme was more accurate, particularly when asymmetric permeability of the tissue boundaries were considered. Yet, the method exhibited limitations for predictions of instantaneous metrics related to the fluid phase, e.g., mass exchange rate. Nonetheless, employing higher-order data exchange schemes may be necessary to understand the biphasic mechanics of cells under lifelike tissue loading states for the whole time history of the simulation. PMID:23809004

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

    E-print Network

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

    2012-07-09

    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. 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.

  15. Fluidized bed combustion: Mechanical systems and chemical processes. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    Not Available

    1993-11-01

    The bibliography contains citations concerning research and development activities of mechanical systems and chemical processes pertaining to fluidized bed combustion systems. Descriptions and evaluations of the following topics are considered: combustion and ignition studies, mechanical elements, heating and cooling systems, industrial chemistry, and chemical process engineering. (Contains 250 citations and includes a subject term index and title list.)

  16. Simulation of trap assisted leakage through thin dielectrics

    NASA Astrophysics Data System (ADS)

    Koz?owski, Grzegorz; D?browski, Jarek

    2010-02-01

    A simple quantum mechanical model was used to investigate the influence of charged defects on trap assisted tunnelling (TAT) current through dielectric films. TAT current behaves in two distinct ways for defects close and far from the interface. Leakage through traps with normal and homogenous distribution of energy states is compared to currents through ideal material with thickness inhomogeneity.

  17. Do capture data from mosquito traps represent reality?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Collectively, the effects of mechanical trap style, the method of trap placement in the field, mosquito activity phase, and other biological phenomena are manifest as sample bias that leads to vector detection failure(s) and/or erroneous predictions of mosquito activity. The goal of this research i...

  18. Guiding neuronal growth with optical trap

    NASA Astrophysics Data System (ADS)

    Feng, Xiuzhou; Xia, Chunlin; Zhu, Tianchun; Li, Chunpeng; Wan, Minghui; Zhang, Ye

    2005-01-01

    Neuronal growth cones navigate over long distances along specific pathways to find their correct targets. The prevailing opinion is that growth cones appear to be guided by four different mechanisms: contact attraction, chemoattraction, contact repulsion, and chemorepulsion. In contrast to existing methods, we use optical trap to guide neuronal growth. The optical trap is a non-contact manipulation technology which is increasingly used for micromanipulation of living cells and organisms. An intense light gradient near the focal region of a near-infrared laser beam gives rise to forces that make possible optical trapping and manipulation of a variety of micron-sized objects. In the developing nervous system, microtubule and actin play a fundamental role. To change the microtubule polymerization by control the density of tubulins or exerting a persistent force on the whole growth cone, we have shown experimentally that we can use optical trap to guide the growth direction of a neuron. In order to guide the neuronal growth direction, a self-contrived optical trap is placed in front of a specific area of the edge of the cell's growth cone. We turned the neuronal growth direction and guided it to the direction we expected. Control over neuronal growth is a fundamental objective in neuroscience and guiding neuronal growth with optical trap may be very important for the formation of neural circuits as well as nerve regeneration.

  19. Formation of interface traps in metal-oxide-semiconductor devices during isochronal annealing after irradiation at 78 K

    Microsoft Academic Search

    N. S. Saks; R. B. Klein; S. Yoon; D. L. Griscom

    1991-01-01

    The mechanisms of interface trap N(it) formation are studied in metal-oxide-semiconductor devices during isochronal annealing after irradiation at 78 K. Two distinct N(it) formation processes are observed at 120 and 250 K. After irradiation but before annealing, some samples were injected with electrons to remove all the radiation-induced positive oxide charges. In these samples, the N(it) formation process at 250

  20. Kinetic mechanism of Nicotiana tabacum myosin-11 defines a new type of a processive motor.

    PubMed

    Diensthuber, Ralph P; Tominaga, Motoki; Preller, Matthias; Hartmann, Falk K; Orii, Hidefumi; Chizhov, Igor; Oiwa, Kazuhiro; Tsiavaliaris, Georgios

    2015-01-01

    The 175-kDa myosin-11 from Nicotiana tabacum (Nt(175kDa)myosin-11) is exceptional in its mechanical activity as it is the fastest known processive actin-based motor, moving 10 times faster than the structurally related class 5 myosins. Although this ability might be essential for long-range organelle transport within larger plant cells, the kinetic features underlying the fast processive movement of Nt(175kDa)myosin-11 still remain unexplored. To address this, we generated a single-headed motor domain construct and carried out a detailed kinetic analysis. The data demonstrate that Nt(175kDa)myosin-11 is a high duty ratio motor, which remains associated with actin most of its enzymatic cycle. However, different from other processive myosins that establish a high duty ratio on the basis of a rate-limiting ADP-release step, Nt(175kDa)myosin-11 achieves a high duty ratio by a prolonged duration of the ATP-induced isomerization of the actin-bound states and ADP release kinetics, both of which in terms of the corresponding time constants approach the total ATPase cycle time. Molecular modeling predicts that variations in the charge distribution of the actin binding interface might contribute to the thermodynamic fine-tuning of the kinetics of this myosin. Our study unravels a new type of a high duty ratio motor and provides important insights into the molecular mechanism of processive movement of higher plant myosins. PMID:25326536

  1. Deciphering the photochemical mechanisms describing the UV-induced processes occurring in solvated guanine monophosphate

    PubMed Central

    Altavilla, Salvatore F.; Segarra-Martí, Javier; Nenov, Artur; Conti, Irene; Rivalta, Ivan; Garavelli, Marco

    2015-01-01

    The photophysics and photochemistry of water-solvated guanine monophosphate (GMP) are here characterized by means of a multireference quantum-chemical/molecular mechanics theoretical approach (CASPT2//CASSCF/AMBER) in order to elucidate the main photo-processes occurring upon UV-light irradiation. The effect of the solvent and of the phosphate group on the energetics and structural features of this system are evaluated for the first time employing high-level ab initio methods and thoroughly compared to those in vacuo previously reported in the literature and to the experimental evidence to assess to which extent they influence the photoinduced mechanisms. Solvated electronic excitation energies of solvated GMP at the Franck-Condon (FC) region show a red shift for the ??* La and Lb states, whereas the energy of the oxygen lone-pair n?* state is blue-shifted. The main photoinduced decay route is promoted through a ring-puckering motion along the bright lowest-lying La state toward a conical intersection (CI) with the ground state, involving a very shallow stationary point along the minimum energy pathway in contrast to the barrierless profile found in gas-phase, the point being placed at the end of the minimum energy path (MEP) thus endorsing its ultrafast deactivation in accordance with time-resolved transient and photoelectron spectroscopy experiments. The role of the n?* state in the solvated system is severely diminished as the crossings with the initially populated La state and also with the Lb state are placed too high energetically to partake prominently in the deactivation photo-process. The proposed mechanism present in solvated and in vacuo DNA/RNA chromophores validates the intrinsic photostability mechanism through CI-mediated non-radiative processes accompanying the bright excited-state population toward the ground state and subsequent relaxation back to the FC region. PMID:25941671

  2. Mechanical property of tubular composites manufactured from braided-pultrusion process

    SciTech Connect

    Byun, J.H.; Lee, S.K. [Korea Institute of Machinery and Metals, Changwon (Korea, Republic of). Composite Materials Group

    1994-12-31

    In order to realize the potential of composite materials, it is imperative to develop a manufacturing process, to understand the microstructures, and to assess the structural performance of the composite. The braided-pultrusion process, which combines the pultrusion process with the braiding technology, has been developed by utilizing a novel resin impregnation device. The goal of the development is to achieve both cost-effectiveness and performance of the composite. The tubular composites of diameter 5.3 mm have been produced using Kevlar 49 fiber and polyester resin. In order to assess the mechanical performance of the composites, an analytical method for predicting the elastic constants has been developed. The analysis includes the geometric model of a unit cell, coordinate transformation, and averaging of stiffness and compliance constants of the constituent materials. The analytic predictions were compared favorably with experimental results.

  3. Mechanical property changes in porous low-k dielectric thin films during processing

    SciTech Connect

    Stan, G., E-mail: gheorghe.stan@nist.gov; Gates, R. S. [Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Kavuri, P. [Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Torres, J.; Michalak, D.; Ege, C.; Bielefeld, J.; King, S. W. [Logic Technology Development, Intel Corporation, Hillsboro, Oregon 97124 (United States)

    2014-10-13

    The design of future generations of Cu-low-k dielectric interconnects with reduced electronic crosstalk often requires engineering materials with an optimal trade off between their dielectric constant and elastic modulus. This is because the benefits associated with the reduction of the dielectric constant by increasing the porosity of materials, for example, can adversely affect their mechanical integrity during processing. By using load-dependent contact-resonance atomic force microscopy, the changes in the elastic modulus of low-k dielectric materials due to processing were accurately measured. These changes were linked to alterations sustained by the structure of low-k dielectric films during processing. A two-phase model was used for quantitative assessments of the elastic modulus changes undergone by the organosilicate skeleton of the structure of porous and pore-filled dielectrics.

  4. Mechanical property changes in porous low-k dielectric thin films during processing

    NASA Astrophysics Data System (ADS)

    Stan, G.; Gates, R. S.; Kavuri, P.; Torres, J.; Michalak, D.; Ege, C.; Bielefeld, J.; King, S. W.

    2014-10-01

    The design of future generations of Cu-low-k dielectric interconnects with reduced electronic crosstalk often requires engineering materials with an optimal trade off between their dielectric constant and elastic modulus. This is because the benefits associated with the reduction of the dielectric constant by increasing the porosity of materials, for example, can adversely affect their mechanical integrity during processing. By using load-dependent contact-resonance atomic force microscopy, the changes in the elastic modulus of low-k dielectric materials due to processing were accurately measured. These changes were linked to alterations sustained by the structure of low-k dielectric films during processing. A two-phase model was used for quantitative assessments of the elastic modulus changes undergone by the organosilicate skeleton of the structure of porous and pore-filled dielectrics.

  5. Final report of ''Fundamental Surface Reaction Mechanisms in Fluorocarbon Plasma-Based Processing''

    SciTech Connect

    Gottlieb S. Oehrlein; H. Anderson; J. Cecchi; D. Graves

    2004-09-21

    This report provides a summary of results obtained in research supported by contract ''Fundamental Surface Reaction Mechanisms in Fluorocarbon Plasma-Based Processing'' (Contract No. DE-FG0200ER54608). In this program we advanced significantly the scientific knowledge base on low pressure fluorocarbon plasmas used for patterning of dielectric films and for producing fluorocarbon coatings on substrates. We characterized important neutral and ionic gas phase species that are incident at the substrate, and the processes that occur at relevant surfaces in contact with the plasma. The work was performed through collaboration of research groups at three universities where significantly different, complementary tools for plasma and surface characterization, computer simulation of plasma and surface processes exist. Exchange of diagnostic tools and experimental verification of key results at collaborating institutions, both experimentally and by computer simulations, was an important component of the approach taken in this work.

  6. Treating chemical mechanical polishing (CMP) wastewater by electro-coagulation-flotation process with surfactant.

    PubMed

    Hu, C Y; Lo, S L; Li, C M; Kuan, W H

    2005-04-11

    The effect of surfactants on the treatment of chemical mechanical polishing (CMP) wastewater by electro-coagulation-flotation (ECF) process was studied. Two surfactants, cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate (SDS) were employed in this study to compare the effect of cationic (CTAB) and anodic (SDS) surfactants on ECF. The cationic surfactant can enhance the removal of the turbidity, but anodic surfactant cannot. It can be explained by the hetero-coagulation theory. Moreover, the addition of CTAB in CMP wastewater can reduce the sludge volume and the flotation/sedimentation time in ECF process. The residual turbidity and dissolved silicon dropped with the increase of charge loading. No CTAB pollution problem exists after the ECF process. PMID:15811659

  7. Simulation of the Press Hardening Process and Prediction of the Final Mechanical Material Properties

    NASA Astrophysics Data System (ADS)

    Hochholdinger, Bernd; Hora, Pavel; Grass, Hannes; Lipp, Arnulf

    2011-08-01

    Press hardening is a well-established production process in the automotive industry today. The actual trend of this process technology points towards the manufacturing of parts with tailored properties. Since the knowledge of the mechanical properties of a structural part after forming and quenching is essential for the evaluation of for example the crash performance, an accurate as possible virtual assessment of the production process is more than ever necessary. In order to achieve this, the definition of reliable input parameters and boundary conditions for the thermo-mechanically coupled simulation of the process steps is required. One of the most important input parameters, especially regarding the final properties of the quenched material, is the contact heat transfer coefficient (IHTC). The CHTC depends on the effective pressure or the gap distance between part and tool. The CHTC at different contact pressures and gap distances is determined through inverse parameter identification. Furthermore a simulation strategy for the subsequent steps of the press hardening process as well as adequate modeling approaches for part and tools are discussed. For the prediction of the yield curves of the material after press hardening a phenomenological model is presented. This model requires the knowledge of the microstructure within the part. By post processing the nodal temperature history with a CCT diagram the quantitative distribution of the phase fractions martensite, bainite, ferrite and pearlite after press hardening is determined. The model itself is based on a Hockett-Sherby approach with the Hockett-Sherby parameters being defined in function of the phase fractions and a characteristic cooling rate.

  8. Recovery of copper from printed circuit boards scraps by mechanical processing and electrometallurgy.

    PubMed

    Veit, Hugo Marcelo; Bernardes, Andréa Moura; Ferreira, Jane Zoppas; Tenório, Jorge Alberto Soares; de Fraga Malfatti, Célia

    2006-10-11

    The constant growth in generation of solid wastes stimulates studies of recycling processes. The electronic scrap is part of this universe of obsolete and/or defective materials that need to be disposed of more appropriately, or then recycled. In this work, printed circuit boards, that are part of electronic scrap and are found in almost all electro-electronic equipments, were studied. Printed circuit boards were collected in obsolete or defective personal computers that are the largest source of this kind of waste. Printed circuit boards are composed of different materials such as polymers, ceramics and metals, which makes the process more difficult. However, the presence of metals, such as copper and precious metals encourage recycling studies. Also the presence of heavy metals, as Pb and Cd turns this scrap into dangerous residues. This demonstrates the need to search for solutions of this kind of residue, in order to have it disposed in a proper way, without harming the environment. At the first stage of this work, mechanical processing was used, as comminution followed by size, magnetic and electrostatic separation. By this process it was possible to obtain a concentrated fraction in metals (mainly Cu, Pb and Sn) and another fraction containing polymers and ceramics. The copper content reached more than 50% in mass in most of the conductive fractions and significant content of Pb and Sn. At the second stage, the fraction concentrated in metals was dissolved with acids and treated in an electrochemical process in order to recover the metals separately, especially copper. The results demonstrate the technical viability of recovering copper using mechanical processing followed by an electrometallurgical technique. The copper content in solution decayed quickly in all the experiments and the copper obtained by electrowinning is above 98% in most of the tests. PMID:16757116

  9. Soil nitrate reducing processes – drivers, mechanisms for spatial variation, and significance for nitrous oxide production

    PubMed Central

    Giles, Madeline; Morley, Nicholas; Baggs, Elizabeth M.; Daniell, Tim J.

    2012-01-01

    The microbial processes of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) are two important nitrate reducing mechanisms in soil, which are responsible for the loss of nitrate (NO3?) and production of the potent greenhouse gas, nitrous oxide (N2O). A number of factors are known to control these processes, including O2 concentrations and moisture content, N, C, pH, and the size and community structure of nitrate reducing organisms responsible for the processes. There is an increasing understanding associated with many of these controls on flux through the nitrogen cycle in soil systems. However, there remains uncertainty about how the nitrate reducing communities are linked to environmental variables and the flux of products from these processes. The high spatial variability of environmental controls and microbial communities across small sub centimeter areas of soil may prove to be critical in determining why an understanding of the links between biotic and abiotic controls has proved elusive. This spatial effect is often overlooked as a driver of nitrate reducing processes. An increased knowledge of the effects of spatial heterogeneity in soil on nitrate reduction processes will be fundamental in understanding the drivers, location, and potential for N2O production from soils. PMID:23264770

  10. Processing, mechanical behavior and biocompatibility of ultrafine grained zirconium fabricated by accumulative roll bonding

    NASA Astrophysics Data System (ADS)

    Jiang, Ling

    The aim of this study is to produce large quantities of bulk zirconium with an ultrafine grained microstructure and with enhanced properties. Accumulative roll bonding (ARB), a severe plastic deformation technique based on rolling, is chosen due to its availability in industrial environment. The texture, microstructure and mechanical behavior of bulk ultrafine grained (ufg) Zr fabricated by accumulative roll bonding is investigated by electron backscatter diffraction, transmission electron microscopy and mechanical testing. A reasonably homogeneous and equiaxed ufg structure, with a large fraction of high angle boundaries (HABs, ˜70%), can be obtained in Zr after only two ARB cycles. The average grain size, counting only HABs (theta>15°), is 400 nm. (Sub)grain size is equal to 320 nm. The yield stress and ultimate tensile stress (UTS) values are nearly double those from conventionally processed Zr with only a slight loss of ductility. Optimum processing conditions include large thickness reductions per pass (˜75%), which enhance grain refinement, and a rolling temperature (T ˜ 0.3Tm) at which a sufficient number of slip modes are activated, with an absence of significant grain growth. Grain refinement takes place by geometrical thinning and grain subdivision by the formation of geometrically necessary boundaries. The formation of equiaxed grains by geometric dynamic recrystallization is facilitated by enhanced diffusion due to adabatic heating. Optical microscopy examination and shear testing suggest accepted bonding quality compared to that achieved in materials processed by diffusion bonding and that obtained in other ARB studies. Biocompatibility of ultrafine grained Zr processed by large strain rolling is studied by evaluating the behavior of human osteoblast cells. It is suggested that ultrafine grained Zr has a similar good biocompatibility as Ti6Al4V alloy and conventional Zr with a large grain size have. The improved mechanical properties together with an excellent biocompatibility make ultrafine grained Zr a promising biomaterial for surgical implants.

  11. Cosmic Ray Acceleration by Magnetic Traps

    E-print Network

    V. N. Zirakashvili

    2001-06-05

    Cosmic ray acceleration in turbulent interstellar medium is considered. Turbulence is treated as ensemble of moving magnetic traps. We derive equations for particle momentum distribution function that describes acceleration of particles in this case. Rate of acceleration calculated is estimated for our Galaxy and compared with ones given by other acceleration mechanisms.

  12. The Spectral Fingerprints and the Sounds of Chemical Mechanical Planarization Processes

    NASA Astrophysics Data System (ADS)

    Philipossian, Ara; Rosales?Yeomans, Daniel

    2006-03-01

    Spectral analysis of friction data obtained during inter layer dielectric chemical mechanical planarization (ILD CMP) was used effectively to elucidate the tribology of the process in terms of stick-slip phenomena by quantifying the total amount of mechanical interaction in the pad-slurry-wafer interface as a function of various pad types and textures, fumed silica concentrations, relative pad-wafer velocities and applied wafer pressures. A new parameter termed the “interfacial interaction index” (?) was defined and determined empirically by integrating the amplitude of the force spectra over a wide range of frequencies. In 85% of the cases investigated, values of ? extracted from individual force spectra quantitatively agreed with the tribological information obtained from Stribeck curve analysis over a wide range of operating conditions. The newly developed method was remarkable from the standpoint of its potential to eliminate having to perform a multitude of experiments needed for constructing and interpreting Stribeck curves. For a given tribological mechanism, analysis of the spectra for various types of pad textures indicated significant differences in the “spectral fingerprint” of various pads depending on their texture, as well as on the type of slurry and processing conditions. This notion was further extended to reproducing the “sound” of CMP by superimposing the sounds and tempi of individual peaks in the spectrum on one another. It is envisaged that the aforementioned pad “fingerprinting” can provide a pathway for fundamental analysis of the effect of pad grooving on stick-slip phenomena which will eventually lead to improved pad designs.

  13. Evaluating Steam Trap Performance 

    E-print Network

    Fuller, N. Y.

    1986-01-01

    Laboratory tests were conducted on several types of steam traps at Holston Defense Corporation in Kingsport, Tennessee. Data from these tests, which determined their relative efficiencies, were used in performing economic analyses to determine...

  14. Multiphoton Magnetooptical Trap

    SciTech Connect

    Wu Saijun; Plisson, Thomas; Brown, Roger C.; Phillips, William D.; Porto, J. V. [Joint Quantum Institute, NIST and University of Maryland, Gaithersburg, Maryland 20899 (United States)

    2009-10-23

    We demonstrate a magnetooptical trap (MOT) configuration which employs optical forces due to light scattering between electronically excited states of the atom. With the standard MOT laser beams propagating along the x and y directions, the laser beams along the z direction are at a different wavelength that couples two sets of excited states. We demonstrate efficient cooling and trapping of cesium atoms in a vapor cell and sub-Doppler cooling on both the red and blue sides of the two-photon resonance. The technique demonstrated in this work may have applications in background-free detection of trapped atoms, and in assisting laser cooling and trapping of certain atomic species that require cooling lasers at inconvenient wavelengths.

  15. Influence of processing history on the mechanical properties and electrical resistivity of polycarbonate - multi-walled carbon nanotubes nanocomposites

    NASA Astrophysics Data System (ADS)

    Choong, Gabriel Y. H.; De Focatiis, Davide S. A.

    2015-05-01

    In this work we investigate the effects of compounding temperature and secondary melt processing on the mechanical response and electrical behaviour of polycarbonate filled with 3 wt% carbon nanotubes. The nanocomposites were melt compounded in an industrial setting at a range of temperatures, and subsequently injection moulded or compression moulded. The surface hardness, uniaxial tensile properties and electrical resistivity were measured. Secondary melt processing is found to be the dominant process in determining the final mechanical properties and resistivity of these materials.

  16. Immune function across generations: integrating mechanism and evolutionary process in maternal antibody transmission.

    PubMed Central

    Grindstaff, Jennifer L; Brodie, Edmund D; Ketterson, Ellen D

    2003-01-01

    The past 30 years of immunological research have revealed much about the proximate mechanisms of maternal antibody transmission and utilization, but have not adequately addressed how these issues are related to evolutionary and ecological theory. Much remains to be learned about individual differences within a species in maternal antibody transmission as well as differences among species in transmission or utilization of antibodies. Similarly, maternal-effects theory has generally neglected the mechanisms by which mothers influence offspring phenotype. Although the environmental cues that generate maternal effects and the consequent effects for offspring phenotype are often well characterized, the intermediary physiological and developmental steps through which the maternal effect is transmitted are generally unknown. Integration of the proximate mechanisms of maternal antibody transmission with evolutionary theory on maternal effects affords an important opportunity to unite mechanism and process by focusing on the links between genetics, environment and physiology, with the ultimate goal of explaining differences among individuals and species in the transfer of immune function from one generation to the next. PMID:14667346

  17. Inactivation mechanisms of lactic acid starter cultures preserved by drying processes.

    PubMed

    Santivarangkna, C; Kulozik, U; Foerst, P

    2008-07-01

    The preservation of lactic acid starter cultures by drying are of increased interest. A further improvement of cell viability is, however, still needed, and the insight into inactivation mechanisms of the cells is a prerequisite. In this present work, we review the inactivation mechanisms of lactic acid starter cultures during drying which are not yet completely understood. Inactivation is not only induced by dehydration inactivation but also by thermal- and cryo-injuries depending on the drying processes employed. The cell membrane has been reported as a major site of damage during drying or rehydration where transitions of membrane phases occur. Some drying processes, such as freeze drying or spray drying, involve subzero or very high temperatures. These physical conditions pose additional stresses to cells during the drying processes. Injuries of cells subjected to freezing temperatures may be due to the high electrolyte concentration (solution effect) or intracellular ice formation, depending on the cooling rate. High temperatures affect most essential cellular components. It is difficult to identify a critical component, although ribosomal functionality is speculated as the primary reason. The activation during storage is mainly due to membrane lipid oxidation, while the storage conditions such as temperature moisture content of the dried starter cultures are important factors. PMID:18266696

  18. Mechanical property evaluation of an Al-2024 alloy subjected to HPT processing

    NASA Astrophysics Data System (ADS)

    Patil, Deepak C.; Venkateswarlu, K.; Kori, S. A.; Das, Goutam; Das, Mousumi; Alhajeri, Saleh N.; Langdon, Terence G.

    2014-08-01

    An aluminum-copper alloy (Al-2024) was successfully subjected to high-pressure torsion (HPT) up to five turns at room temperature under an applied pressure of 6.0 GPa. The Al-2024 alloy is used as a fuselage structural material in the aerospace sector. Mechanical properties of the HPT-processed Al-2024 alloy were evaluated using the automated ball indentation technique. This test is based on multiple cycles of loading and unloading where a spherical indenter is used. After two and five turns of HPT, the Al-2024 alloy exhibited a UTS value of ~1014 MPa and ~1160 MPa respectively, at the edge of the samples. The microhardness was measured from edges to centers for all HPT samples. These results clearly demonstrate that processing by HPT gives a very significant increase in tensile properties and the microhardness values increase symmetrically from the centers to the edges. Following HPT, TEM examination of the five-turn HPT sample revealed the formation of high-angle grain boundaries and a large dislocation density with a reduced average grain size of ~80 nm. These results also demonstrate that high-pressure torsion is a processing tool for developing nanostructures in the Al-2024 alloy with enhanced mechanical properties.

  19. Development of neural mechanisms of conflict and error processing during childhood: implications for self-regulation.

    PubMed

    Checa, Purificación; Castellanos, M C; Abundis-Gutiérrez, Alicia; Rosario Rueda, M

    2014-01-01

    Regulation of thoughts and behavior requires attention, particularly when there is conflict between alternative responses or when errors are to be prevented or corrected. Conflict monitoring and error processing are functions of the executive attention network, a neurocognitive system that greatly matures during childhood. In this study, we examined the development of brain mechanisms underlying conflict and error processing with event-related potentials (ERPs), and explored the relationship between brain function and individual differences in the ability to self-regulate behavior. Three groups of children aged 4-6, 7-9, and 10-13 years, and a group of adults performed a child-friendly version of the flanker task while ERPs were registered. Marked developmental changes were observed in both conflict processing and brain reactions to errors. After controlling by age, higher self-regulation skills are associated with smaller amplitude of the conflict effect but greater amplitude of the error-related negativity. Additionally, we found that electrophysiological measures of conflict and error monitoring predict individual differences in impulsivity and the capacity to delay gratification. These findings inform of brain mechanisms underlying the development of cognitive control and self-regulation. PMID:24795676

  20. Oxidation mechanism of diethyl ether: a complex process for a simple molecule.

    PubMed

    Di Tommaso, Stefania; Rotureau, Patricia; Crescenzi, Orlando; Adamo, Carlo

    2011-08-28

    A large number of organic compounds, such as ethers, spontaneously form unstable peroxides through a self-propagating process of autoxidation (peroxidation). Although the hazards of organic peroxides are well known, the oxidation mechanisms of peroxidizable compounds like ethers reported in the literature are vague and often based on old experiments, carried out in very different conditions (e.g. atmospheric, combustion). With the aim to (partially) fill the lack of information, in this paper we present an extensive Density Functional Theory (DFT) study of autoxidation reaction of diethyl ether (DEE), a chemical that is largely used as solvent in laboratories, and which is considered to be responsible for various accidents. The aim of the work is to investigate the most probable reaction paths involved in the autoxidation process and to identify all potential hazardous intermediates, such as peroxides. Beyond the determination of a complex oxidation mechanism for such a simple molecule, our results suggest that the two main reaction channels open in solution are the direct decomposition (?-scission) of DEE radical issued of the initiation step and the isomerization of the peroxy radical formed upon oxygen attack (DEEOO?). A simple kinetic evaluation of these two competing reaction channels hints that radical isomerization may play an unexpectedly important role in the global DEE oxidation process. Finally industrial hazards could be related to the hydroperoxide formation and accumulation during the chain propagation step. The resulting information may contribute to the understanding of the accidental risks associated with the use of diethyl ether. PMID:21735019

  1. Initiation process and propagation mechanism of positive streamer discharge in water

    NASA Astrophysics Data System (ADS)

    Fujita, Hidemasa; Kanazawa, Seiji; Ohtani, Kiyonobu; Komiya, Atsuki; Kaneko, Toshiro; Sato, Takehiko

    2014-12-01

    The aim of this study was to clarify the initiation process and the propagation mechanism of positive underwater streamers under the application of pulsed voltage with a duration of 10 ?s, focusing on two different theories of electrical discharges in liquids: the bubble theory and the direct ionization theory. The initiation process, which is the time lag from the beginning of voltage application to streamer inception, was found to be related to the bubble theory. In this process, Joule heating resulted in the formation of a bubble cluster at the tip of a needle electrode. Streamer inception was observed from the tip of a protrusion on the surface of this bubble cluster, which acted as a virtual sharp electrode to enhance the local electric field to a level greater than 10 MV/cm. Streak imaging of secondary streamer propagation showed that luminescence preceded gas channel generation, suggesting a mechanism of direct ionization in water. Streak imaging of primary streamer propagation revealed intermittent propagation, synchronized with repetitive pulsed currents. Shadowgraph imaging of streamers synchronized with the light emission signal indicated the possibility of direct ionization in water for primary streamer propagation as well as for secondary streamer propagation.

  2. Phase discrimination ability in Mongolian gerbils provides evidence for possible processing mechanism of mistuning detection.

    PubMed

    Klinge-Strahl, Astrid; Parnitzke, Timo; Beutelmann, Rainer; Klump, Georg M

    2013-01-01

    Compared to humans, Mongolian gerbils (Meriones unguiculatus) are much more sensitive at detecting mistuning of frequency components of a harmonic complex (Klinge and Klump. J Acoust Soc Am 128:280-290, 2010). One processing mechanism suggested to result in the high sensitivity involves evaluating the phase shift that gradually develops between the mistuned and the remaining components in the same or separate auditory filters. To investigate if this processing mechanism may explain the observed sensitivity, we determined the gerbils' thresholds to detect a constant phase shift in a component of a harmonic complex that is introduced without a frequency shift. The gerbils' detection thresholds for constant phase shifts were considerably lower for a high-frequency component (6,400 Hz) than for a low-frequency component (400 Hz) of a 200-Hz harmonic complex and increased with decreasing stimulus duration. Compared to the phase shifts calculated from the mistuning detection thresholds, the detection thresholds for constant phase shifts were similar to those for gradual phase shifts for the low-frequency harmonic but considerably lower for the high-frequency harmonic. A simulation of the processing of harmonic complexes by the gerbil's peripheral auditory filters when components are phase shifted shows waveform changes comparable to those assessed for mistuning detection Klinge and Klump (J Acoust Soc Am 128:280-290, 2010) and provides evidence that detection of the gradual phase shifts may underlie mistuning detection. PMID:23716246

  3. Mechanical, thermal and optical properties of the SPS-processed polycrystalline Nd:YAG

    NASA Astrophysics Data System (ADS)

    Sokol, M.; Kalabukhov, S.; Kasiyan, V.; Rothman, A.; Dariel, M. P.; Frage, N.

    2014-12-01

    The present study deals with a comprehensive comparison of the mechanical and functional properties of Nd:YAG single crystals with those of the polycrystalline ceramics (PCs), undoped and LiF-doped, processed by Spark Plasma Sintering (SPS). The polycrystalline ceramics have higher mechanical properties (hardness, bending strength and thermal shock resistance) than the single crystals. The optical transmittance of the LiF-doped PC Nd:YAG is significantly higher than that of the undoped one and is close to that of the single crystal. With respect to other optical and thermal properties, i.e. refraction index, absorption coefficient, extinction ratio, thermo-optic coefficient, fluorescence and thermal conductivity, no significant differences were observed between the single crystals and the polycrystalline ceramic.

  4. Synthesis mechanism of heterovalent Sn2O3 nanosheets in oxidation annealing process

    NASA Astrophysics Data System (ADS)

    Zhao, Jun-Hua; Tan, Rui-Qin; Yang, Ye; Xu, Wei; Li, Jia; Shen, Wen-Feng; Wu, Guo-Qiang; Yang, Xu-Feng; Song, Wei-Jie

    2015-07-01

    Heterovalent Sn2O3 nanosheets were fabricated via an oxidation annealing process and the formation mechanism was investigated. The temperature required to complete the phase transformation from Sn3O4 to Sn2O3 was considered. Two contrasting experiments showed that both oxygen and heating were not necessary conditions for the phase transition. Sn2O3 was formed under an argon protective atmosphere by annealing and could also be obtained at room temperature by exposing Sn3O4 in atmosphere or dispersing in ethanol. The synthesis mechanism was proposed and discussed. This fundamental research is important for the technological applications of intermediate tin oxide materials. Project supported by the National Natural Science Foundation of China (Grant Nos. 21377063, 51102250, 21203226, and 21205127) and the Personnel Training Foundation of Quzhou University, China (Grant No. BSYJ201412).

  5. Search For Trapped Antihydrogen

    E-print Network

    Andresen, Gorm B; Baquero-Ruiz, Marcelo; Bertsche, William; Bowe, Paul D; Bray, Crystal C; Butler, Eoin; Cesar, Claudio L; Chapman, Steven; Charlton, Michael; Fajans, Joel; Friesen, Tim; Fujiwara, Makoto C; Gill, David R; Hangst, Jeffrey S; Hardy, Walter N; Hayano, Ryugo S; Hayden, Michael E; Humphries, Andrew J; Hydomako, Richard; Jonsell, Svante; Jørgensen, Lars V; Kurchaninov, Lenoid; Lambo, Ricardo; Madsen, Niels; Menary, Scott; Nolan, Paul; Olchanski, Konstantin; Olin, Art; Povilus, Alexander; Pusa, Petteri; Robicheaux, Francis; Sarid, Eli; Nasr, Sarah Seif El; Silveira, Daniel M; So, Chukman; Storey, James W; Thompson, Robert I; van der Werf, Dirk P; Wilding, Dean; Wurtele, Jonathan S; Yamazaki, Yasunori

    2011-01-01

    We present the results of an experiment to search for trapped antihydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator. Sensitive diagnostics of the temperatures, sizes, and densities of the trapped antiproton and positron plasmas have been developed, which in turn permitted development of techniques to precisely and reproducibly control the initial experimental parameters. The use of a position-sensitive annihilation vertex detector, together with the capability of controllably quenching the superconducting magnetic minimum trap, enabled us to carry out a high-sensitivity and low-background search for trapped synthesised antihydrogen atoms. We aim to identify the annihilations of antihydrogen atoms held for at least 130 ms in the trap before being released over ~30 ms. After a three-week experimental run in 2009 involving mixing of 10^7 antiprotons with 1.3 10^9 positrons to produce 6 10^5 antihydrogen atoms, we have identified six antiproton annihilation events that are consist...

  6. Connecting mechanics and bone cell activities in the bone remodeling process: an integrated finite element modeling.

    PubMed

    Hambli, Ridha

    2014-01-01

    Bone adaptation occurs as a response to external loadings and involves bone resorption by osteoclasts followed by the formation of new bone by osteoblasts. It is directly triggered by the transduction phase by osteocytes embedded within the bone matrix. The bone remodeling process is governed by the interactions between osteoblasts and osteoclasts through the expression of several autocrine and paracrine factors that control bone cell populations and their relative rate of differentiation and proliferation. A review of the literature shows that despite the progress in bone remodeling simulation using the finite element (FE) method, there is still a lack of predictive models that explicitly consider the interaction between osteoblasts and osteoclasts combined with the mechanical response of bone. The current study attempts to develop an FE model to describe the bone remodeling process, taking into consideration the activities of osteoclasts and osteoblasts. The mechanical behavior of bone is described by taking into account the bone material fatigue damage accumulation and mineralization. A coupled strain-damage stimulus function is proposed, which controls the level of autocrine and paracrine factors. The cellular behavior is based on Komarova et al.'s (2003) dynamic law, which describes the autocrine and paracrine interactions between osteoblasts and osteoclasts and computes cell population dynamics and changes in bone mass at a discrete site of bone remodeling. Therefore, when an external mechanical stress is applied, bone formation and resorption is governed by cells dynamic rather than adaptive elasticity approaches. The proposed FE model has been implemented in the FE code Abaqus (UMAT routine). An example of human proximal femur is investigated using the model developed. The model was able to predict final human proximal femur adaptation similar to the patterns observed in a human proximal femur. The results obtained reveal complex spatio-temporal bone adaptation. The proposed FEM model gives insight into how bone cells adapt their architecture to the mechanical and biological environment. PMID:25152881

  7. Quality-by-design: an integrated process analytical technology approach to determine the nucleation and growth mechanisms during a dynamic pharmaceutical coprecipitation process.

    PubMed

    Wu, Huiquan; Khan, Mansoor A

    2011-05-01

    The objective of this study was to demonstrate the feasibility of using an integrated process analytical technology (PAT) approach to determine nucleation and growth mechanisms of a dynamic naproxen (drug)-Eudragit L100 (polymer) coprecipitation process. The influence of several thermodynamically important formulation and process variables (drug/polymer ratio, alcohol, and water usages) on coprecipitation process characteristics was investigated via real-time in situ focused beam reflectance measurement (FBRM) monitoring and near real-time particle vision microscopy measurement. The final products were characterized by near-infrared (NIR) spectroscopy and NIR chemical imaging microscopy. The coprecipitation nucleation induction time (t(ind) ) was measured by both FBRM trend statistics and process trajectory method, respectively. Furthermore, nucleation kinetics was evaluated based on t(ind) measurement and corresponding supersaturation ratio (S) estimated. It was found that plots of ln(t(ind) ) versus (ln(2) S)(-1) consist of two linear segments and are consistent with classical primary nucleation mechanisms. Apparently, the coprecipitation process is governed by heterogeneous primary nucleation mechanism at low S (14 ? S ? 503) and by homogeneous primary nucleation mechanism at high S (1216 ? S ? 3649). Off-line characterizations collectively supported this statement. Therefore, it demonstrated that integration real-time PAT process monitoring with first-principles modeling and off-line product characterization could enhance understanding to coprecipitation process dynamics and nucleation/growth mechanisms, which is impossible via off-line techniques alone. PMID:21374627

  8. Analysis of optical trap mediated aerosol coalescence

    NASA Astrophysics Data System (ADS)

    Mistry, N. S.; Power, R.; Anand, S.; McGloin, D.; Almohamedi, A.; Downie, M.; Reid, J. P.; Hudson, A. J.

    2012-10-01

    The use of optical tweezers for the analysis of aerosols is valuable for understanding the dynamics of atmospherically relevant particles. However to be able to make accurate measurements that can be directly tied to real-world phenomena it is important that we understand the influence of the optical trap on those processes. One process that is seemingly straightforward to study with these techniques is binary droplet coalescence, either using dual beam traps, or by particle collision with a single trapped droplet. This binary coalescence is also of interest in many other processes that make use of dense aerosol sprays such as spray drying and the use of inhalers for drug delivery in conditions such as asthma or hay fever. In this presentation we discuss the use of high speed (~5000 frames per second) video microscopy to track the dynamics of particles as they approach and interact with a trapped aqueous droplet and develop this analysis further by considering elastic light scattering from droplets as they undergo coalescence. We find that we are able to characterize the re-equilibration time of droplets of the same phase after they interact and that the trajectories taken by airborne particles influenced by an optical trap are often quite complex. We also examine the role of parameters such as the salt concentration of the aqueous solutions used and the influence of laser wavelength.

  9. Charge trapping induced by plasma in alumina electrode surface investigated by thermoluminescence and optically stimulated luminescence

    SciTech Connect

    Ambrico, P. F. [CNR-IMIP Sezione di Bari, Via Orabona, 4 I-70126 Bari (Italy); Ambrico, M. [CNR-IMIP Sezione di Bari, Via Orabona, 4 I-70126 Bari (Italy); CNISM Unita di Ricerca Bari Universita, Universita degli Studi di Bari, Via Amendola, 173 I-70126-Bari (Italy); Schiavulli, L. [CNISM Unita di Ricerca Bari Universita, Universita degli Studi di Bari, Via Amendola, 173 I-70126-Bari (Italy); INFN-Sezione di Bari, Via Amendola, 173 I-70126 Bari (Italy); Dipartimento Interateneo di Fisica, Universita degli Studi di Bari, Via Amendola, 173 I-70126 Bari (Italy); Ligonzo, T.; Augelli, V. [CNISM Unita di Ricerca Bari Universita, Universita degli Studi di Bari, Via Amendola, 173 I-70126-Bari (Italy); Dipartimento Interateneo di Fisica, Universita degli Studi di Bari, Via Amendola, 173 I-70126 Bari (Italy)

    2009-02-02

    The plasma of a dielectric barrier discharge can fill traps in the alumina that cover the electrode. Trap energies and lifetimes are estimated by thermoluminescence and optically stimulated luminescence. Comparison with similar results for traps created by other radiation sources clarifies the mechanisms regulating this effect. Alumina's trap energies are approximately 1 eV, and the traps remain active for several days after plasma exposure. These results could be important to keep dielectric barrier discharge plasmas uniform since a trapped charge can be an electron reservoir.

  10. Cold trapped positrons and progress to cold antihydrogen

    E-print Network

    Estrada, John Karl, 1970-

    2002-01-01

    A new physical mechanism for positron accumulation is explained and demonstrated. Strongly magnetized Rydberg positronium is formed and then ionized, allowing us to trap equal numbers of either positrons or electrons over ...

  11. Line tying of interchange modes in a nearly collisionless mirror-trapped plasma

    Microsoft Academic Search

    Guy Vandegrift

    1989-01-01

    If the confining potential of electrostatically trapped electrons fluctuates, then the number of trapped electrons also fluctuates. The linear relationship between potential fluctuations and the number of trapped electrons is investigated, considering two loss mechanisms for a nearly collisionless plasma: (1) small-angle collisions (diffusion), and (2) large-angle collisions. This nearly collisionless model predicts the line tying of interchange modes in

  12. Carbon Disulfide (CS2) Mechanisms in Formation of Atmospheric Carbon Dioxide (CO2) Formation from Unconventional Shale Gas Extraction and Processing Operations and Global Climate Change.

    PubMed

    Rich, Alisa L; Patel, Jay T

    2015-01-01

    Carbon disulfide (CS2) has been historically associated with the production of rayon, cellophane, and carbon tetrachloride. This study identifies multiple mechanisms by which CS2 contributes to the formation of CO2 in the atmosphere. CS2 and other associated sulfide compounds were found by this study to be present in emissions from unconventional shale gas extraction and processing (E&P) operations. The breakdown products of CS2; carbonyl sulfide (COS), carbon monoxide (CO), and sulfur dioxide (SO2) are indirect greenhouse gases (GHGs) that contribute to CO2 levels in the atmosphere. The heat-trapping nature of CO2 has been found to increase the surface temperature, resulting in regional and global climate change. The purpose of this study is to identify five mechanisms by which CS2 and the breakdown products of CS2 contribute to atmospheric concentrations of CO2. The five mechanisms of CO2 formation are as follows: Chemical Interaction of CS2 and hydrogen sulfide (H2S) present in natural gas at high temperatures, resulting in CO2 formation;Combustion of CS2 in the presence of oxygen producing SO2 and CO2;Photolysis of CS2 leading to the formation of COS, CO, and SO2, which are indirect contributors to CO2 formation;One-step hydrolysis of CS2, producing reactive intermediates and ultimately forming H2S and CO2;Two-step hydrolysis of CS2 forming the reactive COS intermediate that reacts with an additional water molecule, ultimately forming H2S and CO2. CS2 and COS additionally are implicated in the formation of SO2 in the stratosphere and/or troposphere. SO2 is an indirect contributor to CO2 formation and is implicated in global climate change. PMID:25987843

  13. Analysis of a Magnetically Trapped Atom Clock

    E-print Network

    D. Kadio; Y. B. Band

    2006-12-12

    We consider optimization of a rubidium atom clock that uses magnetically trapped Bose condensed atoms in a highly elongated trap, and determine the optimal conditions for minimum Allan variance of the clock using microwave Ramsey fringe spectroscopy. Elimination of magnetic field shifts and collisional shifts are considered. The effects of spin-dipolar relaxation are addressed in the optimization of the clock. We find that for the interstate interaction strength equal to or larger than the intrastate interaction strengths, a modulational instability results in phase separation and symmetry breaking of the two-component condensate composed of the ground and excited hyperfine clock levels, and this mechanism limits the clock accuracy.

  14. Analysis of a magnetically trapped atom clock

    SciTech Connect

    Kadio, D. [Departments of Chemistry and Electro-Optics, and Ilse Katz Center for Nano-Science, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Band, Y. B. [Departments of Chemistry and Electro-Optics, and Ilse Katz Center for Nano-Science, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Atomic Physics Division, A267 Physics, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

    2006-11-15

    We consider optimization of a rubidium atom clock that uses magnetically trapped Bose condensed atoms in a highly elongated trap, and determine the optimal conditions for minimum Allan variance of the clock using microwave Ramsey fringe spectroscopy. Elimination of magnetic field shifts and collisional shifts are considered. The effects of spin-dipolar relaxation are addressed in the optimization of the clock. We find that for the interstate interaction strength equal to or larger than the intrastate interaction strengths, a modulational instability results in phase separation and symmetry breaking of the two-component condensate composed of the ground and excited hyperfine clock levels, and this mechanism limits the clock accuracy.

  15. INFLUENCE OF WELDING PROCESSES ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF DISSIMILAR AUSTENITIC-FERRITIC STAINLESS STEEL WELDS

    Microsoft Academic Search

    G. Madhusudhan Reddy; T. Mohandas; A. Sambasiva Rao; V. V. Satyanarayana

    2005-01-01

    Dissimilar metal welding of austenitic (AISI 304)-ferritic (AISI 430) stainless steel has been taken up to understand the influence of the welding process on microstructure and mechanical properties. Fusion welding processes, namely, gas tungsten arc welding (GTAW), electron beam welding (EBW), and friction welding, have been employed. The GTAW and EBW processes were selected to understand the heat input effects,

  16. H Diffusion for Impurity and Defect Passivation: A Physical Model for Solar Cell Processing; Preprint

    SciTech Connect

    Sopori, B. L.; Zhang, Y.; Reedy, R.

    2002-05-01

    We propose a physical model for diffusion of H in Si containing impurities and defects. The diffusion occurs via several parallel mechanisms, involving complex formation (trapping) and dissociation (detrapping) at impurities and defects, hopping in lattice interstitial sites, and charge-state conversion. The role of bulk and process-induced traps is considered to explain observations from plasma, ion implantation, and PECVD-nitridation processes.

  17. Fatigue properties of a biomedical 316L steel processed by surface mechanical attrition

    NASA Astrophysics Data System (ADS)

    Sun, Z.; Chemkhi, M.; Kanoute, P.; Retraint, D.

    2014-08-01

    This work deals with the influence of surface mechanical attrition treatment (SMAT) on fatigue properties of a medical grade 316L stainless steel. Metallurgical parameters governed by SMAT such as micro-hardness and nanocrystalline layer are characterized using different techniques. Low cycle fatigue tests are performed to investigate the fatigue properties of untreated and SMAT-processed samples. The results show that the stress amplitude of SMAT- processed samples with two different treatment intensities is significantly enhanced compared to untreated samples, while the fatigue strength represented by the number of cycles to failure is not improved in the investigated strain range. The enhancement in the stress amplitude of treated samples can be attributed to the influence of the SMAT affected layer.

  18. Effects of Mechanical Vibration and Wall Thickness on Microstructure and Mechanical Properties of AZ91D Magnesium Alloy Processed by Expendable Pattern Shell Casting

    NASA Astrophysics Data System (ADS)

    Jiang, Wenming; Fan, Zitian; Chen, Xu; Wang, Benjing; Wu, Hebao

    2015-04-01

    Mechanical vibration was introduced into the solidification process of AZ91D magnesium alloy during the expendable pattern shell casting process, and the combined effects of mechanical vibration and wall thickness on the microstructure and mechanical properties were investigated. The results indicate that with the increase of wall thickness, the morphologies in ?-Mg phase and ?-Mg17Al12 phase of the samples obtained without vibration evolved from a fine dendrite to a coarse dendrite and from a fine continuous network structure to a coarse continuous network structure, respectively, and the mechanical properties and density of AZ91D alloy continuously decreased. With the application of mechanical vibration, the coarser dendrites transformed into fine equiaxed grains, and the previous coarse continuous network structure of the ?-Mg17Al12 phase was changed to a discontinuous granular morphology. Meanwhile, the mechanical properties and density of AZ91D alloy greatly increased. The effect of mechanical vibration on the microstructure and mechanical properties increased with increasing vibration frequency and wall thickness. The fractographs of the tensile samples show a change in fracture surface from brittle to that of a tough fracture with the addition of vibration.

  19. Novel Ultrahigh Vacuum System for Chip-Scale Trapped Ion Quantum Computing

    NASA Astrophysics Data System (ADS)

    Chen, Shaw-Pin

    2011-06-01

    This presentation reports the experimental results of an ultrahigh vacuum (UHV) system as a scheme to implement scalable trapped-ion quantum computers that use micro-fabricated ion traps as fundamental building blocks. The novelty of this system resides in our design, material selection, mechanical liability, low complexity of assembly, and reduced signal interference between DC and RF electrodes. Our system utilizes RF isolation and onsite-filtering topologies to attenuate AC signals generated from the resonator. We use a UHV compatible printed circuit board (PCB) material to perform DC routing, while the RF high and RF ground received separated routing via wire-wrapping. The standard PCB fabrication process enabled us to implement ceramic-based filter components adjacent to the chip trap. The DC electrodes are connected to air-side electrical feed through using four 25D adaptors made with polyether ether ketone (PEEK). The assembly process of this system is straight forward and in-chamber structure is self-supporting. We report on initial testing of this concept with a linear chip trap fabricated by the Sandia National Labs.

  20. Experimental study of vapor-cell magneto-optical traps for efficient trapping of radioactive atoms

    NASA Astrophysics Data System (ADS)

    Atutov, S. N.; Calabrese, R.; Facchini, A.; Stancari, G.; Tomassetti, L.

    2009-05-01

    We have studied magneto-optical traps (MOTs) for efficient on-line trapping of radioactive atoms. After discussing a model of the trapping process in a vapor cell and its efficiency, we present the results of detailed experimental studies on Rb MOTs. Three spherical cells of different sizes were used. These cells can be easily replaced, while keeping the rest of the apparatus unchanged: atomic sources, vacuum conditions, magnetic field gradients, sizes and power of the laser beams, detection system. By direct comparison, we find that the trapping efficiency only weakly depends on the MOT cell size. It is also found that the trapping efficiency of the MOT with the smallest cell, whose diameter is equal to the diameter of the trapping beams, is about 40% smaller than the efficiency of larger cells. Furthermore, we also demonstrate the importance of two factors: a long coated tube at the entrance of the MOT cell, used instead of a diaphragm; and the passivation with an alkali vapor of the coating on the cell walls, in order to minimize the losses of trappable atoms. These results guided us in the construction of an efficient large-diameter cell, which has been successfully employed for on-line trapping of Fr isotopes at INFN’s national laboratories in Legnaro, Italy.