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Sample records for processes trapping mechanisms

  1. Degradation Mechanisms of Solution-Processed Planar Perovskite Solar Cells: Thermally Stimulated Current Measurement for Analysis of Carrier Traps.

    PubMed

    Qin, Chuanjiang; Matsushima, Toshinori; Fujihara, Takashi; Potscavage, William J; Adachi, Chihaya

    2016-01-01

    Degradation mechanisms of CH3 NH3 PbI3 -based planar perovskite solar cells (PSCs) are investigated using a thermally stimulated current technique. Hole traps lying above the valence-band edge of the CH3 NH3 PbI3 are detected in PSCs degraded by continuous simulated solar illumination. One source of the hole traps is the photodegradation of CH3 NH3 PbI3 in the presence of water. PMID:26598398

  2. Electron trapping mechanisms in magnetron injection guns

    NASA Astrophysics Data System (ADS)

    Pagonakis, Ioannis Gr.; Piosczyk, Bernhard; Zhang, Jianhua; Illy, Stefan; Rzesnicki, Tomasz; Hogge, Jean-Philippe; Avramidis, Konstantinos; Gantenbein, Gerd; Thumm, Manfred; Jelonnek, John

    2016-02-01

    A key parameter for the gyrotron operation and efficiency is the presence of trapped electrons. Two electron trapping mechanisms can take place in gyrotrons: (i) the adiabatic trap and (ii) the magnetic potential well. Their influence on the gyrotron operation is analyzed. Two gun design criteria are then proposed to suppress both mechanisms in order to minimize the risk of possible problems. Experimental results of three high power gyrotrons are presented and their performance is correlated to the presence of populations of trapped electrons. Finally, some very general gun design principles are presented for the limitation of harmful electron trapping.

  3. Quantum information processing with trapped ions

    NASA Astrophysics Data System (ADS)

    King, Brian E.

    2002-03-01

    A quantum computer is composed of quantum bits (two-level systems) which can store superpositions of 0 and 1. An array of trapped ions was proposed as attractive architecture for a quantum computer by Cirac and Zoller (J. I. Cirac and P. Zoller, Phys. Rev. Lett. 74, 4091 (1995)). In such a computer, the quantum bits are "wired" together by virtue of their collective motion in the trap, and externally applied laser light entangles quantum bits and allows the construction of quantum logic gates. The past six years have seen considerable progress in implementing quantum logic processing in trapped ion systems: demonstration of a two-bit quantum XOR gate; production of Schroedinger cat states; the generation of a maximally entangled state of four trapped ions; and demonstration of a decoherence-free quantum memory. Micromachining techniques have been used to manufacture ion traps that confine linear ion arrays within a few tens of microns. Although much remains to be understood about the mechanisms of decoherence in trapped ion systems, they are strong candidates for scalable quantum logic processing.

  4. 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.

    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.

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

    SciTech Connect

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

    2014-08-14

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

  6. 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.

  7. Kinetics and mechanism of Dionaea muscipula trap closing.

    PubMed

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

    2008-02-01

    The Venus flytrap (Dionaea muscipula) possesses an active trapping mechanism to capture insects with one of the most rapid movements in the plant kingdom, as described by Darwin. This article presents a detailed experimental investigation of trap closure by mechanical and electrical stimuli and the mechanism of this process. Trap closure consists of three distinctive phases: a silent phase with no observable movement; an accelerated movement of the lobes; and the relaxation of the lobes in their closed state, resulting in a new equilibrium. Uncouplers and blockers of membrane channels were used to investigate the mechanisms of different phases of closing. Uncouplers increased trap closure delay and significantly decreased the speed of trap closure. Ion channel blockers and aquaporin inhibitors increased time of closing. Transmission of a single electrical charge between a lobe and the midrib causes closure of the trap and induces an electrical signal propagating between both lobes and midrib. The Venus flytrap can accumulate small subthreshold charges, and when the threshold value is reached, the trap closes. Repeated application of smaller charges demonstrates the summation of stimuli. The cumulative character of electrical stimuli points to the existence of electrical memory in the Venus flytrap. The observed fast movement can be explained by the hydroelastic curvature model without invoking buckling instability. The new hydroelastic curvature mechanism provides an accurate description of the authors' experimental data. PMID:18065564

  8. Mechanical Performance of Rat, Mouse and Mole Spring Traps, and Possible Implications for Welfare Performance

    PubMed Central

    Baker, Sandra E.; Ellwood, Stephen A.; Tagarielli, Vito L.; Macdonald, David W.

    2012-01-01

    Lethal spring traps are widely used for killing small mammals in the UK. Many require government approval, based primarily on humaneness. However, mole traps and break-back traps for rats and mice are exempt; those available vary widely in price and apparent quality. The EU is considering implementing a Trapping Directive that would alter UK legislation, and a recent report advised the EU that trapping legislation should cover all trapped species and encourage improvement of traps. Mechanical trap performance is often used as an indicator of welfare impact. We examined the mechanical evidence for scope to improve the welfare standards of rat, mouse and mole spring traps. We measured mechanical performance among a range of rat, mouse and mole traps. Impact momentum values varied 6-8 fold, and clamping force values 4-5.5 fold, among traps for killing each species. There was considerable overlap in the performance of rat and mouse traps. Trap-opening angle and spring type were related to impact momentum and clamping force in traps for both species. There was no relationship between price and mechanical performance in traps for any species, except talpa mole traps. We are unable to judge the direct welfare impact of the traps tested, but rather the potential welfare threat associated with their exemption from approval. The wide variation in mechanical performance in traps for each species, overlap in performance between rat and mouse traps and increasing availability of weaker plastic rodent traps indicate considerable scope for improving the humaneness of spring traps for rats, mice and moles. We conclude that all such traps should be subject to the UK approval process. New welfare categories might improve trap standards further. Our results could also help improve rodent trap design and assist consumers in selecting more powerful traps. Many thousands of rats, mice and moles might benefit. PMID:22768073

  9. 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.

  10. Eliminating Impurity Traps in the Silane Process

    NASA Technical Reports Server (NTRS)

    Coleman, L. M.

    1982-01-01

    Redistribution reaction section of silane process progressively separates heavier parts of chlorosilane feedstock until light silane product is available for pyrolysis. Small amount of liquid containing impurities is withdrawn from processing stages in which trapping occurs and passed to earlier processing stage in which impurities tend to be removed via chemical reactions.

  11. Quantum information processing with trapped Ca(+) ions.

    PubMed

    Gulde, S; Hffner, H; Riebe, M; Lancaster, G; Becher, C; Eschner, J; Schmidt-Kaler, F; Chuang, I L; Blatt, R

    2003-07-15

    Quantum information processing is performed with single trapped Ca(+) ions, stored in a linear Paul trap and laser-cooled to the ground state of their harmonic quantum motion. Composite laser-pulse sequences were used to implement SWAP gate, phase gate and controlled-NOT gate operations. Stark shifts on the quantum-bit transitions were precisely measured and compensated. For a demonstration of quantum information processing, a Deutsch-Jozsa algorithm has been implemented using two quantum bits encoded on a single ion. PMID:12869313

  12. Quantum information processing with trapped Ca+ ions

    NASA Astrophysics Data System (ADS)

    Gulde, S.; Hffner, H.; Riebe, M.; et al.

    2003-07-01

    Quantum information processing is performed with single trapped Ca+ ions, stored in a linear Paul trap and laser-cooled to the ground state of their harmonic quantum motion. Composite laser-pulse sequences were used to implement SWAP gate, phase gate and controlled-NOT gate operations. Stark shifts on the quantum-bit transitions were precisely measured and compensated. For a demonstration of quantum information processing, a Deutsch-Jozsa algorithm has been implemented using two quantum bits encoded on a single ion.

  13. CO2 Capillary-Trapping Processes in Deep Saline Aquifers

    NASA Astrophysics Data System (ADS)

    Gershenzon, Naum I.; Soltanian, Mohamadreza; Ritzi, Robert W., Jr.; Dominic, David F.

    2014-05-01

    The idea of reducing the Earth's greenhouse effect by sequestration of CO2 into the Earth's crust has been discussed and evaluated for more than two decades. Deep saline aquifers are the primary candidate formations for realization of this idea. Evaluation of reservoir capacity and the risk of CO2 leakage require a detailed modeling of the migration and distribution of CO2 in the subsurface structure. There is a finite risk that structural (or hydrodynamic) trapping by caprock may be compromised (e.g. by improperly abandoned wells, stratigraphic discontinuities, faults, etc.). Therefore, other trapping mechanisms (capillary trapping, dissolution, and mineralization) must be considered. Capillary trapping may be very important in providing a "secondary-seal", and is the focus of our investigation. The physical mechanism of CO2 trapping in porous media by capillary trapping incorporates three related processes, i.e. residual trapping, trapping due to hysteresis of the relative permeability, and trapping due to hysteresis of the capillary pressure. Additionally CO2 may be trapped in heterogeneous media due to difference in capillary pressure entry points for different materials. The amount of CO2 trapped by these processes is a complicated nonlinear function of the spatial distribution of permeability, permeability anisotropy, capillary pressure, relative permeability of brine and CO2, permeability hysteresis and residual gas saturation (as well as the rate, total amount and placement of injected CO2). Geological heterogeneities essentially affect the dynamics of a CO2 plume in subsurface environments. Recent studies have led to new conceptual and quantitative models for sedimentary architecture in fluvial deposits over a range of scales that are relevant to the performance of some deep saline reservoirs [1, 2]. We investigated how the dynamics of a CO2 plume, during and after injection, is influenced by the hierarchical and multi-scale stratal architecture in such reservoirs. The results strongly suggest that representing these small scales features, and representing how they are organized within a hierarchy of larger-scale features, is critical to understanding capillary trapping processes. References [1] Bridge, J.S. (2006), Fluvial facies models: Recent developments, in Facies Models Revisited, SEPM Spec. Publ., 84, edited by H. W. Posamentier and R. G. Walker, pp. 85-170, Soc. for Sediment. Geol. (SEPM), Tulsa, Okla [2] Ramanathan, R., A. Guin, R.W. Ritzi, D.F. Dominic, V.L. Freedman, T.D. Scheibe, and I.A. Lunt (2010), Simulating the heterogeneity in channel belt deposits: Part 1. A geometric-based methodology and code, Water Resources Research, v. 46, W04515.

  14. Hydrogen-Trapping Mechanisms in Nanostructured Steels

    NASA Astrophysics Data System (ADS)

    Szost, B. A.; Vegter, R. H.; Rivera-Daz-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.

  15. Mechanisms for mechanical trapping of geologically sequestered carbon dioxide

    PubMed Central

    Cohen, Yossi; Rothman, Daniel H.

    2015-01-01

    Carbon dioxide (CO2) sequestration in subsurface reservoirs is important for limiting atmospheric CO2 concentrations. However, a complete physical picture able to predict the structure developing within the porous medium is lacking. We investigate theoretically reactive transport in the long-time evolution of carbon in the brine–rock environment. As CO2 is injected into a brine–rock environment, a carbonate-rich region is created amid brine. Within the carbonate-rich region minerals dissolve and migrate from regions of high-to-low concentration, along with other dissolved carbonate species. This causes mineral precipitation at the interface between the two regions. We argue that precipitation in a small layer reduces diffusivity, and eventually causes mechanical trapping of the CO2. Consequently, only a small fraction of the CO2 is converted to solid mineral; the remainder either dissolves in water or is trapped in its original form. We also study the case of a pure CO2 bubble surrounded by brine and suggest a mechanism that may lead to a carbonate-encrusted bubble owing to structural diffusion. PMID:25792961

  16. Trapped rubber processing for advanced composites

    NASA Technical Reports Server (NTRS)

    Marra, P. J.

    1976-01-01

    Trapped rubber processing is a molding technique for composites in which precast silicone rubber is placed within a closed cavity where it thermally expands against the composite's surface supported by the vessel walls. The method has been applied by the Douglas Aircraft Company, under contract to NASA-Langley, to the design and fabrication of 10 DC-10 graphite/epoxy upper aft rudder assemblies. A three-bay development tool form mold die has been designed and manufactured, and tooling parameters have been established. Fabrication procedures include graphite layup, assembly of details in the tool, and a cure cycle. The technique has made it possible for the cocured fabrication of complex primary box structures otherwise impracticable via standard composite material processes.

  17. Trapping mechanism in overdamped ratchets with quenched noise

    NASA Astrophysics Data System (ADS)

    Zarlenga, D. G.; Larrondo, H. A.; Arizmendi, C. M.; Family, Fereydoon

    2007-05-01

    A trapping mechanism is observed and proposed as the origin of the anomalous behavior recently discovered in transport properties of overdamped ratchets subject to an external oscillatory drive in the presence of quenched noise. In particular, this mechanism is shown to appear whenever the quenched disorder strength is greater than a threshold value. The minimum disorder strength required for the existence of traps is determined by studying the trap structure in a disorder configuration space. An approximation to the trapping probability density function in a disordered region of finite length included in an otherwise perfect ratchet lattice is obtained. The mean velocity of the particles and the diffusion coefficient are found to have a nonmonotonic dependence on the quenched noise strength due to the presence of the traps.

  18. A Mechanically Tunable Microfluidic Cell-Trapping Device

    PubMed Central

    Zhu, Jing; Shang, Junyi; Olsen, Timothy; Liu, Kun; Brenner, David; Lin, Qiao

    2015-01-01

    Controlled manipulation, such as isolation, positioning and trapping of cells, is important in basic biological research and clinical diagnostics. Micro/nanotechnologies have been enabling more effective and efficient cell trapping than possible with conventional platforms. Currently available micro/nanoscale methods for cell trapping, however, still lack flexibility in precisely controlling the number of trapped cells. We exploited the large compliance of elastomers to create an array of cell-trapping microstructures, whose dimensions can be mechanically modulated by inducing uniformly distributed strain via application of external force on the chip. The device consists of two elastomer polydimethylsiloxane (PDMS) sheets, one of which bears dam-like, cup-shaped geometries to physically capture cells. The mechanical modulation is used to tune the characteristics of cell trapping to capture a predetermined number of cells, from single cells to multiple cells. Thus, enhanced utility and flexibility for practical applications can be attained, as demonstrated by tunable trapping of MCF-7 cells, a human breast cancer cell line. PMID:25821347

  19. Kinetics and Mechanism of Dionaea muscipula Trap Closing1[C][OA

    PubMed Central

    Volkov, Alexander G.; Adesina, Tejumade; Markin, Vladislav S.; Jovanov, Emil

    2008-01-01

    The Venus flytrap (Dionaea muscipula) possesses an active trapping mechanism to capture insects with one of the most rapid movements in the plant kingdom, as described by Darwin. This article presents a detailed experimental investigation of trap closure by mechanical and electrical stimuli and the mechanism of this process. Trap closure consists of three distinctive phases: a silent phase with no observable movement; an accelerated movement of the lobes; and the relaxation of the lobes in their closed state, resulting in a new equilibrium. Uncouplers and blockers of membrane channels were used to investigate the mechanisms of different phases of closing. Uncouplers increased trap closure delay and significantly decreased the speed of trap closure. Ion channel blockers and aquaporin inhibitors increased time of closing. Transmission of a single electrical charge between a lobe and the midrib causes closure of the trap and induces an electrical signal propagating between both lobes and midrib. The Venus flytrap can accumulate small subthreshold charges, and when the threshold value is reached, the trap closes. Repeated application of smaller charges demonstrates the summation of stimuli. The cumulative character of electrical stimuli points to the existence of electrical memory in the Venus flytrap. The observed fast movement can be explained by the hydroelastic curvature model without invoking buckling instability. The new hydroelastic curvature mechanism provides an accurate description of the authors' experimental data. PMID:18065564

  20. Mechanism of follicular trapping: similarities and differences in trapping of antibody-complexed antigens and carbon particles in the follicles of the spleen

    SciTech Connect

    Groeneveld, P.H.; Eikelenboom, P.; van Rooijen, N.

    1983-02-01

    Both immune complexes and carbon particles were trapped in spleen follicles soon after intravenous injection. The localization pattern of carbon particles and immune complexes were identical 24 hr after injection. Since there is no reason to believe that lymphocytes are involved in the transport of carbon particles from the marginal zone towards the follicle centers, these results indicate that follicular trapping is based on a purely mechanical process. Pretreatment with endotoxin completely prevented the trapping of immune complexes but not carbon particles. Endotoxin administered after the injection of immune complexes caused the rapid removal of trapped complexes from the follicles. However, the effect of endotoxin on trapped carbon particles was less pronounced. Apart from a mechanical trapping of diffusing compounds in the follicular web, a distinct phase is suggested in which immune complexes are fixed to and retained on the surface of the follicular dendritic cells.

  1. 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.

  2. Quantum information processing with trapped electrons and superconducting electronics

    NASA Astrophysics Data System (ADS)

    Daniilidis, Nikos; Gorman, Dylan J.; Tian, Lin; Hffner, Hartmut

    2013-07-01

    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 nonlinearities of the potential of coupling electrodes near a trapped particle, and can be implemented using standard charged-particle traps. 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 hybrid platforms using trapped electrons and superconducting electronics.

  3. Mechanical model of the ultrafast underwater trap of Utricularia

    NASA Astrophysics Data System (ADS)

    Joyeux, Marc; Vincent, Olivier; Marmottant, Philippe

    2011-02-01

    The underwater traps of the carnivorous plants of the Utricularia species catch their prey through the repetition of an “active slow deflation followed by passive fast suction” sequence. In this paper, we propose a mechanical model that describes both phases and strongly supports the hypothesis that the trap door acts as a flexible valve that buckles under the combined effects of pressure forces and the mechanical stimulation of trigger hairs, and not as a panel articulated on hinges. This model combines two different approaches, namely (i) the description of thin membranes as triangle meshes with strain and curvature energy, and (ii) the molecular dynamics approach, which consists of computing the time evolution of the position of each vertex of the mesh according to Langevin equations. The only free parameter in the expression of the elastic energy is the Young's modulus E of the membranes. The values for this parameter are unequivocally obtained by requiring that the trap model fires, like real traps, when the pressure difference between the outside and the inside of the trap reaches about 15 kPa. Among other results, our simulations show that, for a pressure difference slightly larger than the critical one, the door buckles, slides on the threshold, and finally swings wide open, in excellent agreement with the sequence observed in high-speed videos.

  4. Integrated optics architecture for trapped-ion quantum information processing

    NASA Astrophysics Data System (ADS)

    Kielpinski, D.; Volin, C.; Streed, E. W.; Lenzini, F.; Lobino, M.

    2015-10-01

    Standard schemes for trapped-ion quantum information processing (QIP) involve the manipulation of ions in a large array of interconnected trapping potentials. The basic set of QIP operations, including state initialization, universal quantum logic, and state detection, is routinely executed within a single array site by means of optical operations, including various laser excitations as well as the collection of ion fluorescence. Transport of ions between array sites is also routinely carried out in microfabricated trap arrays. However, it is still not possible to perform optical operations in parallel across all array sites. The lack of this capability is one of the major obstacles to scalable trapped-ion QIP and presently limits exploitation of current microfabricated trap technology. Here we present an architecture for scalable integration of optical operations in trapped-ion QIP. We show theoretically that diffractive mirrors, monolithically fabricated on the trap array, can efficiently couple light between trap array sites and optical waveguide arrays. Integrated optical circuits constructed from these waveguides can be used for sequencing of laser excitation and fluorescence collection. Our scalable architecture supports all standard QIP operations, as well as photon-mediated entanglement channels, while offering substantial performance improvements over current techniques.

  5. Influence of small-scale fluvial architecture on CO2 trapping processes in deep brine reservoirs

    NASA Astrophysics Data System (ADS)

    Gershenzon, Naum I.; Ritzi, Robert W.; Dominic, David F.; Soltanian, Mohamadreza; Mehnert, Edward; Okwen, Roland T.

    2015-10-01

    A number of important candidate CO2 reservoirs exhibit sedimentary architecture reflecting fluvial deposition. Recent studies have led to new conceptual and quantitative models for sedimentary architecture in fluvial deposits over a range of scales that are relevant to CO2 injection and storage. We used a geocellular modeling approach to represent this multiscaled and hierarchical sedimentary architecture. With this model, we investigated the dynamics of CO2 plumes, during and after injection, in such reservoirs. The physical mechanism of CO2 trapping by capillary trapping incorporates a number of related processes, i.e., residual trapping, trapping due to hysteresis of the relative permeability, and trapping due to hysteresis of the capillary pressure. Additionally, CO2 may be trapped due to differences in capillary entry pressure for different textural sedimentary facies (e.g., coarser-grained versus finer-grained cross sets). The amount of CO2 trapped by these processes depends upon a complex system of nonlinear and hysteretic characteristic relationships including how relative permeability and capillary pressure vary with brine and CO2 saturation. The results strongly suggest that representing small-scale features (decimeter to meter), including their organization within a hierarchy of larger-scale features, and representing their differences in characteristic relationships can all be critical to understanding trapping processes in some important candidate CO2 reservoirs.

  6. Determination of active oxide trap density and 1/f noise mechanism in RESURF LDMOS transistors

    NASA Astrophysics Data System (ADS)

    elik-Butler, Z.; Mahmud, M. I.; Hao, P.; Hou, F.; Amey, B. L.; Pendharkar, S.

    2015-09-01

    The physical origin of majority charge carrier fluctuations in the SiO2 interface of Si at accumulation has been investigated and analyzed for differently processed and voltage-rated reduced surface field (RESURF), lateral-double-diffused MOS (LDMOS) transistors. Surface carrier mobility fluctuation due to remote Coulomb scattering by the trapped charge in the gate oxide is identified as the dominant physical mechanism for LDMOS 1/f noise irrespective of process technologies. A significant contribution to the measured noise has been noted from the surface majority carrier mobility fluctuation due to trapped charge at the accumulation region of the extended drain region, dominant over other sources including the surface minority charge carrier fluctuations in the channel. Active oxide trap density was characterized spatially and for the first time up to ?0.4 eV above the conduction band-edge of Si. The interface trap density in the unstressed devices (?8 106 cm-2) increased more than an order of magnitude (?1 108 cm-2) after the devices were stressed for 10,000 sec at their individual worst drain current and on-resistance degradation conditions. The extracted Si/SiO2 interface trap density above the silicon conduction band edge was found to be several orders of magnitude lower than that reported for silicon mid-gap energies, even after stressing. Since the traps near the quasi-Fermi level for electrons are active in trapping-detrapping, and the Fermi level is energetically positioned above the conduction band edge of Si in the investigated devices as compared to the previously reported observations, the lower trap density obtained here is an indication for reversal of the well-known exponential trap energy distribution beyond the conduction band-edge of Si. These findings shift the focus from the channel to the gate overlap section of the extended drain and the quality of the Si/SiO2 interface in that region.

  7. Mechanical occlusions: diagnostic traps and key points of the report.

    PubMed

    Taourel, P; Alili, C; Pages, E; Curros Doyon, F; Millet, I

    2013-01-01

    Management of mechanical occlusion, particularly of the small intestine, has altered considerably over recent years, with a change of paradigm and the indication for surgery depending on the cause of the occlusion and any signs of entrapment or strangulation. It is therefore important today to make a positive diagnosis of mechanical occlusion, to assess its degree, its location and its cause, and to look for signs of entrapment and strangulation. Only computer tomography can provide the answers to these different questions. The aim of this paper is to provide a reminder of the CT signs that enable us to confirm diagnosis of the various aspects of mechanical occlusion of the stomach and duodenum, small intestine or colon, to emphasize and illustrate the diagnostic traps in CT and to set out the key points of a CT report of mechanical occlusion. PMID:23773530

  8. Mechanical processes in biochemistry.

    PubMed

    Bustamante, Carlos; Chemla, Yann R; Forde, Nancy R; Izhaky, David

    2004-01-01

    Mechanical processes are involved in nearly every facet of the cell cycle. Mechanical forces are generated in the cell during processes as diverse as chromosomal segregation, replication, transcription, translation, translocation of proteins across membranes, cell locomotion, and catalyzed protein and nucleic acid folding and unfolding, among others. Because force is a product of all these reactions, biochemists are beginning to directly apply external forces to these processes to alter the extent or even the fate of these reactions hoping to reveal their underlying molecular mechanisms. This review provides the conceptual framework to understand the role of mechanical force in biochemistry. PMID:15189157

  9. 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. This work is supported by IARPA/ARO and DARPA.

  10. Pore-scale study of capillary trapping mechanism during CO2 injection in geological formations

    SciTech Connect

    Bandara, Uditha C.; Tartakovsky, Alexandre M.; Palmer, Bruce J.

    2011-11-01

    Geological sequestration of CO{sub 2} gas emerged as a promising solution for reducing amount of green house gases in atmosphere. A number of continuum scale models are available to describe the transport phenomena of CO{sub 2} sequestration. These models rely heavily on a phenomenological description of subsurface transport phenomena and the predictions can be highly uncertain. Pore-scale models provide a better understanding of fluid displacement processes, nonetheless such models are rare. In this work we use a Smoothed Particle Hydrodynamics (SPH) model to study pore-scale displacement and capillary trapping mechanisms of super-critical CO{sub 2} in the subsurface. Simulations are carried out to investigate the effects of gravitational, viscous, and capillary forces in terms of Gravity, Capillary, and Bond numbers. Contrary to the other published continuum scale investigations, we found that not only Gravity number but also Capillary number plays an important role on the fate of injected CO{sub 2}. For large Gravity numbers (on the order of 10), most of the injected CO{sub 2} reaches the cap-rock due to gravity segregation. A significant portion of CO{sub 2} gets trapped by capillary forces when Gravity number is small (on the order of 0.1). When Gravity number is moderately high (on the order of 1), trapping patterns are heavily dependent on Capillary number. If Capillary number is very small (less than 0.001), then capillary forces dominate the buoyancy forces and a significant fraction of injected CO{sub 2} is trapped by the capillary forces. Conversely, if Capillary number is high (higher than 0.001), capillary trapping is relatively small since buoyancy dominates the capillary forces. In addition, our simulations reveal different types of capillary trapping and flow displacement mechanisms during and after injection. In gravity dominated cases leave behind was the widespread trapping mechanism. Division was the primary trapping mechanism in viscous dominated cases. In capillary dominated cases, snap-off of the CO{sub 2} plume is the most commonly observed displacement mechanism. Large CO{sub 2} blobs are created due to coalescence mechanism.

  11. Solution-processed polymer photodetectors with trap-assisted photomultiplication

    NASA Astrophysics Data System (ADS)

    Han, ZiHong; Zhang, Hui; Tian, QiuShuo; Li, LingLiang; Zhang, FuJun

    2015-05-01

    Here, we report a trap-assisted photomultiplication (PM) phenomenon in solution-processed organic photodetectors (OPDs) using poly(3-hexylthiophene) (P3HT): indene-C60 bisadduct (ICBA) as the active layer. The maximum external quantum efficiency (EQE) is 685% for the device with 2% ICBA doping ratio, which is much higher than that of OPDs with P3HT:ICBA (1:1) as the active layer. The PM phenomenon is attributed to the hole tunneling injection assisted by trapped electron in ICBA near Al cathode, which can be demonstrated from the EQE spectra and transient photocurrent curves of OPDs with different ICBA doping ratios.

  12. Vacancy trapping mechanism for hydrogen bubble formation in metal

    SciTech Connect

    Liu Yuelin; Zhang Ying; Zhou Hongbo; Lu Guanghong; Liu Feng; Luo, G.-N.

    2009-05-01

    We reveal the microscopic vacancy trapping mechanism for H bubble formation in W based on first-principles calculations of the energetics of H-vacancy interaction and the kinetics of H segregation. Vacancy provides an isosurface of optimal charge density that induces collective H binding on its internal surface, a prerequisite for the formation of H{sub 2} molecule and nucleation of H bubble inside the vacancy. The critical H density on the vacancy surface before the H{sub 2} formation is found to be 10{sup 19}-10{sup 20} H atoms per m{sup 2}. We believe that such mechanism is generally applicable for H bubble formation in metals and metal alloys.

  13. Integration of Advanced Optics for Trapped Ion Quantum Information Processing

    NASA Astrophysics Data System (ADS)

    Noek, Rachel M.

    Trapped ion systems are the leading candidate for quantum information processing because many of the critical components have already been demonstrated. Scaling trapped ion systems to large numbers of ions is currently believed possible, but much work remains to prove it. Microfabricated surface ion traps are increasing in popularity for their ease of mass production and their ability to manipulate individual ions and interact arbitrary pairs of ions. Even with the advent of scalable ion traps, detection of an individual ion trapped in a high vacuum poses a challenge. The internal state of the ion chosen for a quantum bit can be measured via exposure to a probe beam that causes one state to scatter light (a "bright" state), but not the other state (a "dark" state). In free space, a single ion acts like a point source that emits in all directions; a standard two inch lens system can only collect about 2% of the light emitted by the ion. Poor light collection results in a high error rate and slow determination of the internal state of the ion. Fast, high fidelity state detection is necessary for quantum error correction and loophole-free Bell experiments at short (less than 100microm) distances, and high efficiency collection is necessary to rapidly interconnect separate quantum computers. We demonstrate state detection fidelities of 99%, 99.856(8)% and 99.915(7) % which correspond to detection times of 10.5, 28.1 and 99.8 us, respectively.

  14. Ultrahigh-Q mechanical oscillators through optical trapping

    NASA Astrophysics Data System (ADS)

    Kimble, H. Jeff

    2011-05-01

    Rapid advances are being made toward optically cooling a single mode of a micro-mechanical system to its quantum ground state and observing quantum behavior at macroscopic scales. Reaching this regime in room-temperature environments requires a stringent condition on the mechanical quality factor Qm and frequency fm, QmfmkBTbath / h , which so far has been marginally satisfied only in a small number of systems. Here we propose and analyze a new class of systems that should enable unprecedented Qmfm values. The technique is based upon using optical forces to ``trap'' and stiffen the motion of a tethered mechanical structure, thereby freeing the resultant mechanical frequencies and decoherence rates from underlying material properties. We have lithographically fabricated a diverse set of planar structures in Silicon Nitride, made measurements of their optical and mechanical properties, and compared these results to numerical models by finite element analysis. This work has been carried out in collaboration with D. E. Chang, K.-K. Ni, R. Norte, O. J. Painter, and D. J. Wilson. Work supported by DARPA ORCHID program, NSF, and NSSEFF.

  15. Mechanics of single kinesin molecules measured by optical trapping nanometry.

    PubMed

    Kojima, H; Muto, E; Higuchi, H; Yanagida, T

    1997-10-01

    We have analyzed the mechanics of individual kinesin molecules by optical trapping nanometry. A kinesin molecule was adsorbed onto a latex bead, which was captured by an optical trap and brought into contact with an axoneme that was bound to a glass surface. The displacement of kinesin during force generation was determined by measuring the position of the beads with nanometer accuracy. As the displacement of kinesin was attenuated because of the compliance of the kinesin-to-bead and kinesin-to-microtubule linkages, the compliance was monitored during force generation and was used to correct the displacement of kinesin. Thus the velocity and the unitary steps could be obtained accurately over a wide force range. The force-velocity curves were linear from 0 to a maximum force at 10 microM and 1 mM ATP, and the maximum force was approximately 7 pN, which is larger by approximately 30% than values previously reported. Kinesin exhibited forward and occasionally backward stepwise displacements with a size of approximately 8 nm. The histograms of step dwell time show a monotonic decrease with time. Model calculations indicate that each kinesin head steps by 16-nm, whereas kinesin molecule steps by 8-nm. PMID:9336196

  16. 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.

  17. Arraying single microbeads in microchannels using dielectrophoresis-assisted mechanical traps

    NASA Astrophysics Data System (ADS)

    Tirapu-Azpiroz, Jaione; Temiz, Yuksel; Delamarche, Emmanuel

    2015-11-01

    Manipulating and immobilizing single microbeads in flowing fluids is relevant for biological assays and chemical tests but typically requires expensive laboratory equipment and trapping mechanisms that are not reversible. In this paper, we present a highly efficient and reversible mechanism for trapping microbeads by combining dielectrophoresis (DEP) with mechanical traps. The integration of planar electrodes and mechanical traps in a microchannel enables versatile manipulation of microbeads via DEP for their docking in recessed structures of mechanical traps. By simulating the combined effects of the hydrodynamic drag and DEP forces on microbeads, we explore a configuration of periodic traps where the beads are guided by the electrodes and immobilized in recess areas of the traps. The design of the electrode layout and operating configuration are optimized for the efficient trapping of single microbeads. We demonstrated the predicted guiding and trapping effectiveness of the design as well as the reversibility of the system on 10 ?m polystyrene beads. Experimental verification used an array of 96 traps in an area of 420 420 ?m2, reaching a trapping efficiency of 63% when 7 Vpp is applied to the electrodes under 80 nl min-1 flow rate conditions, and 98% of bead release when the voltage is turned off.

  18. Modeling trapping mechanism for PCB adsorption on activated carbon

    NASA Astrophysics Data System (ADS)

    Jensen, Bjørnar; Kvamme, Bjørn; Kuznetsova, Tatyana; Oterhals, A.˚ge

    2012-12-01

    The levels of polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran (PCDD/F) and dioxin-like polychlorinated biphenyl (DL-PCB) in fishmeal and fish oil produced for use in feed for salmon is above present European legislation levels in some regions of the world and different decontamination approaches have been proposed [1]. One of these is adsorption on activated carbon. This approach appears to be efficient for adsorption of PCDD/F but less efficient for DL-PCB [2]. Activated carbon consists of slit pores with average sizes of 20 - 50 Ångstroms. One hypothesis [2] for the mechanism of trapping DL-PCB is reduced ability for intramolecular movements of the PCB molecules inside the slit pores. In order to investigate this hypothesis we have used quantum mechanics [3] to characterize two DL-PCB congeners, respectively congener 77 (3,3',4,4'-Tetrachlorobiphenyl) and congener 118 (2,3',4,4',5-Pentachlorobiphenyl) and Triolein (18:1) [4] as a major constituent of the solvent fish oil. A model for activated carbon was constructed using a crystal structure of graphite from the American Mineralogist Crystal Structure Database [5]. The crystal structure used was originally from Wyckoff [6]. A small program had to be written to generate the desired graphite structure as it contains no less than 31232 Carbon atoms. Partial atomic charges were estimated using QM with DFT/B3LYP/6-311+g** and SM6 [7].

  19. Qubit Manipulations Techniques for Trapped-Ion Quantum Information Processing

    NASA Astrophysics Data System (ADS)

    Gaebler, John; Tan, Ting; Lin, Yiheng; Bowler, Ryan; Jost, John; Meier, Adam; Knill, Emanuel; Leibfried, Dietrich; Wineland, David; Ion Storage Team

    2013-05-01

    We report recent results on qubit manipulation techniques for trapped-ions towards scalable quantum information processing (QIP). We demonstrate a platform-independent benchmarking protocol for evaluating the performance of Clifford gates, which form a basis for fault-tolerant QIP. We report a demonstration of an entangling gate scheme proposed by Bermudez et al. [Phys. Rev. A. 85, 040302 (2012)] and achieve a fidelity of 0.974(4). This scheme takes advantage of dynamic decoupling which protects the qubit against dephasing errors. It can be applied directly on magnetic-field-insensitive states, and provides a number of simplifications in experimental implementation compared to some other entangling gates with trapped ions. We also report preliminary results on dissipative creation of entanglement with trapped-ions. Creation of an entangled pair does not require discrete logic gates and thus could reduce the level of quantum-coherent control needed for large-scale QIP. Supported by IARPA, ARO contract No. EAO139840, ONR, and the NIST Quantum Information Program.

  20. Origin of traps and charge transport mechanism in hafnia

    SciTech Connect

    Islamov, D. R. Gritsenko, V. A.; Cheng, C. H.; Chin, A.

    2014-12-01

    In this study, we demonstrated experimentally and theoretically that oxygen vacancies are responsible for the charge transport in HfO{sub 2}. Basing on the model of phonon-assisted tunneling between traps, and assuming that the electron traps are oxygen vacancies, good quantitative agreement between the experimental and theoretical data of current-voltage characteristics was achieved. The thermal trap energy of 1.25 eV in HfO{sub 2} was determined based on the charge transport experiments.

  1. 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).

  2. Evidence of interfacial charge trapping mechanism in polyaniline/reduced graphene oxide nanocomposites

    NASA Astrophysics Data System (ADS)

    Islam, Rakibul; Papathanassiou, Anthony N.; Chan Yu King, Roch; Brun, Jean-Franois; Roussel, Frederick

    2015-08-01

    Relaxation mechanisms in polyaniline (PANI)/Reduced Graphene Oxide (RGO) nanocomposites are investigated using broad band dielectric spectroscopy. The multilayered nanostructural features of the composites and the intimate interactions between PANI and RGO are evidenced by field emission scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. Increasing the RGO fraction in the composites results in a relaxation process observed at a frequency of ca. 5 kHz. This mechanism is associated with an electrical charge trapping phenomenon occurring at the PANI/RGO interfaces. The dielectric relaxation processes are interpreted according to the Sillars approach and the results are consistent with the presence of conducting prolate spheroids (RGO) embedded into a polymeric matrix (PANI). Dielectric permittivity data are analyzed within the framework of the Kohlrausch-William-Watts model, evidencing a Debye-like relaxation process.

  3. A preliminary assessment of the contribution of CO2 trapping mechanisms at the Ketzin pilot site

    NASA Astrophysics Data System (ADS)

    Klein, E.; De Lucia, M.; Kempka, T.; Tillner, E.; Khn, M.

    2012-04-01

    The FP7 European project CO2CARE aims to support the large-scale demonstration of the CCS technology through the development of site abandonment procedures and technologies which guarantee the fulfilment of the requirements for geological CO2 Storage. One of these requirements is the evolution of the storage site towards long-term stability. Four trapping mechanisms are acting towards long-term stabilization and immobilisation of CO2: 1. Structural trapping, 2. Residual trapping, 3. Dissolution trapping, and 4. Mineral trapping. The quantitative contribution of each of these trapping mechanisms will be site- and time-specific. By means of numerical modelling the four trapping mechanisms are evaluated in two separate steps for the Ketzin pilot site, where CO2 is injected into a saline aquifer at a depth of about 630 m to 700 m. The contribution of structural, residual and dissolution trapping is determined by dynamic modelling using the Schlumberger Eclipse 100 black-oil simulator based on the latest version of the history matched static geological model of the Stuttgart Formation (CO2MAN project). Mineral trapping capacity is evaluated through geochemical batch simulations using the PHREEQC simulator. Fluid and mineral composition are provided by a broad set of core analysis and experimental determinations (CO2SINK and CO2MAN projects) conducted for the Ketzin pilot site. Data on the dissolved CO2 amount and water saturation supplied by the dynamic simulations are used to adjust the boundary conditions of the geochemical models. With regard to the total contribution of the four CO2 trapping mechanisms, being estimated for the time span of 3,000 years, the initial dominance of structural trapping decreases with the increase of dissolution trapping. It is expected that 50% of CO2 are dissolved in the formation fluid within 500 years after injection, wherefrom a fraction slowly starts to incorporate into minerals due to chemical precipitation (mineral trapping). Residual trapping is determined by the migration behaviour of CO2 and residual gas saturation among others. As for mineral trapping in particular, of all carbonate minerals included in the model (siderite, calcite, magnesite and dolomite), siderite is the only one precipitating at the Ketzin pilot site. Variations of the reservoir pressure (and therefore of the amount of dissolved CO2) in the expected range of 55 to 76 bar were found to have a negligible effect on mineral alteration. Decreasing the water saturation on the other hand, results in faster but quantitatively smaller reactions. The total change in mineral volume after 3,000 years can be considered irrelevant in terms of porosity changes.

  4. Adiabatic processes realized with a trapped Brownian particle.

    PubMed

    Martnez, Ignacio A; Roldn, dgar; Dinis, Luis; Petrov, Dmitri; Rica, Ral A

    2015-03-27

    The ability to implement adiabatic processes in the mesoscale is of key importance in the study of artificial or biological micro- and nanoengines. Microadiabatic processes have been elusive to experimental implementation due to the difficulty in isolating Brownian particles from their fluctuating environment. Here we report on the experimental realization of a microscopic quasistatic adiabatic process employing a trapped Brownian particle. We circumvent the complete isolation of the Brownian particle by designing a protocol where both characteristic volume and temperature of the system are changed in such a way that the entropy of the system is conserved along the process. We compare the protocols that follow from either the overdamped or underdamped descriptions, demonstrating that the latter is mandatory in order to obtain a vanishing average heat flux to the particle. We provide analytical expressions for the distributions of the fluctuating heat and entropy and verify them experimentally. Our protocols could serve to implement the first microscopic engine that is able to attain the fundamental limit for the efficiency set by Carnot. PMID:25860731

  5. Adiabatic Processes Realized with a Trapped Brownian Particle

    NASA Astrophysics Data System (ADS)

    Martnez, Ignacio A.; Roldn, dgar; Dinis, Luis; Petrov, Dmitri; Rica, Ral A.

    2015-03-01

    The ability to implement adiabatic processes in the mesoscale is of key importance in the study of artificial or biological micro- and nanoengines. Microadiabatic processes have been elusive to experimental implementation due to the difficulty in isolating Brownian particles from their fluctuating environment. Here we report on the experimental realization of a microscopic quasistatic adiabatic process employing a trapped Brownian particle. We circumvent the complete isolation of the Brownian particle by designing a protocol where both characteristic volume and temperature of the system are changed in such a way that the entropy of the system is conserved along the process. We compare the protocols that follow from either the overdamped or underdamped descriptions, demonstrating that the latter is mandatory in order to obtain a vanishing average heat flux to the particle. We provide analytical expressions for the distributions of the fluctuating heat and entropy and verify them experimentally. Our protocols could serve to implement the first microscopic engine that is able to attain the fundamental limit for the efficiency set by Carnot.

  6. 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

  7. Hydrodynamic mechanisms of cell and particle trapping in microfluidics

    PubMed Central

    Karimi, A.; Yazdi, S.; Ardekani, A. M.

    2013-01-01

    Focusing and sorting cells and particles utilizing microfluidic phenomena have been flourishing areas of development in recent years. These processes are largely beneficial in biomedical applications and fundamental studies of cell biology as they provide cost-effective and point-of-care miniaturized diagnostic devices and rare cell enrichment techniques. Due to inherent problems of isolation methods based on the biomarkers and antigens, separation approaches exploiting physical characteristics of cells of interest, such as size, deformability, and electric and magnetic properties, have gained currency in many medical assays. Here, we present an overview of the cell/particle sorting techniques by harnessing intrinsic hydrodynamic effects in microchannels. Our emphasis is on the underlying fluid dynamical mechanisms causing cross stream migration of objects in shear and vortical flows. We also highlight the advantages and drawbacks of each method in terms of throughput, separation efficiency, and cell viability. Finally, we discuss the future research areas for extending the scope of hydrodynamic mechanisms and exploring new physical directions for microfluidic applications. PMID:24404005

  8. Genomic Mechanisms Accounting for the Adaptation to Parasitism in Nematode-Trapping Fungi

    PubMed Central

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

    2013-01-01

    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

  9. Arbitrary waveform generator for quantum information processing with trapped ions

    NASA Astrophysics Data System (ADS)

    Bowler, R.; Warring, U.; Britton, J. W.; Sawyer, B. C.; Amini, J.

    2013-03-01

    Atomic ions confined in multi-electrode traps have been proposed as a basis for scalable quantum information processing. This scheme involves transporting ions between spatially distinct locations by use of time-varying electric potentials combined with laser or microwave pulses for quantum logic in specific locations. We report the development of a fast multi-channel arbitrary waveform generator for applying the time-varying electric potentials used for transport and for shaping quantum logic pulses. The generator is based on a field-programmable gate array controlled ensemble of 16-bit digital-to-analog converters with an update frequency of 50 MHz and an output range of 10 V. The update rate of the waveform generator is much faster than relevant motional frequencies of the confined ions in our experiments, allowing diabatic control of the ion motion. Numerous pre-loaded sets of time-varying voltages can be selected with 40 ns latency conditioned on real-time signals. Here we describe the device and demonstrate some of its uses in ion-based quantum information experiments, including speed-up of ion transport and the shaping of laser and microwave pulses.

  10. Toward scalable ion traps for quantum information processing

    NASA Astrophysics Data System (ADS)

    Amini, J. M.; Uys, H.; Wesenberg, J. H.; Seidelin, S.; Britton, J.; Bollinger, J. J.; Leibfried, D.; Ospelkaus, C.; VanDevender, A. P.; Wineland, D. J.

    2010-03-01

    In this paper, we report the design, fabrication and preliminary testing of a 150 zone ion trap array built in a 'surface-electrode' geometry microfabricated on a single substrate. We demonstrate the transport of atomic ions between the legs of a 'Y'-type junction and measure the in-situ heating rates for the ions. The trap design demonstrates the use of a basic component design library that can be quickly assembled to form structures optimized for a particular experiment.

  11. Use dependence of tetrodotoxin block of sodium channels: a revival of the trapped-ion mechanism.

    PubMed Central

    Conti, F; Gheri, A; Pusch, M; Moran, O

    1996-01-01

    The use-dependent block of sodium channels by tetrodotoxin (TTX) has been studied in cRNA-injected Xenopus oocytes expressing the alpha-subunit of rat brain IIA channels. The kinetics of stimulus-induced extra block are consistent with an underlying relaxation process involving only three states. Cumulative extra block induced by repetitive stimulations increases with hyperpolarization, with TTX concentration, and with extracellular Ca2+ concentration. We have developed a theoretical model based on the suggestion by Salgado et al. that TTX blocks the extracellular mouth of the ion pore less tightly when the latter has its external side occupied by a cation, and that channel opening favors a tighter binding by allowing the escape of the trapped ion. The model provides an excellent fit of the data, which are consistent with Ca2+ being more efficient than Na+ in weakening TTX binding and with bound Ca2+ stabilizing the closed state of the channel, as suggested by Armstrong and Cota. Reports arguing against the trapped-ion mechanism are critically discussed. PMID:8874004

  12. Integrated superconducting photon detectors for ion trap quantum information processing

    NASA Astrophysics Data System (ADS)

    Slichter, D. H.; Verma, V. B.; Nam, S. W.; Leibfried, D.; Wineland, D. J.

    2014-03-01

    Quantum state measurement of trapped ions relies on detecting fluorescence photons from a laser-driven atomic transition. Typically, the ion fluorescence is collected by high-numerical-aperture (NA) optics and detected using a camera or photomultiplier tube. However, the quantum efficiency of these detectors is below 40% at the wavelengths of interest for many ion species (generally in the UV). Furthermore, the collection optics are bulky and have a limited field of view, making it difficult to scale this method up to simultaneous detection in multiple locations. These issues can be addressed by integrating high-NA photon detectors into the ion trap structure. Superconducting nanowire single-photon detectors (SNSPDs) have demonstrated quantum efficiencies above 90% and have collection areas large enough to give the desired NA. SNSPDs use simple, compact bias and readout electronics and could be multiplexed to allow simultaneous independent readout from many individual trap zones. We report progress on integrating an SNSPD into a surface-electrode RF ion trap, including measurements of quantum efficiency and performance in the presence of RF trapping potentials. This work has been supported by IARPA, the NIST Quantum Information Program, and the NRC Postdoctoral Fellowship.

  13. 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.

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

    PubMed

    Home, Jonathan P; Hanneke, David; Jost, John D; Amini, Jason M; Leibfried, Dietrich; Wineland, David J

    2009-09-01

    Large-scale quantum information processors must be able to transport and maintain quantum information and repeatedly perform logical operations. Here, we show a combination of all of the fundamental elements required to perform scalable quantum computing through the use of qubits stored in the internal states of trapped atomic ions. We quantified the repeatability of a multiple-qubit operation and observed no loss of performance despite qubit transport over macroscopic distances. Key to these results is the use of different pairs of 9Be+ hyperfine states for robust qubit storage, readout, and gates, and simultaneous trapping of 24Mg+ "re-cooling" ions along with the qubit ions. PMID:19661380

  15. Evaluation of the Forrester-Hepburn mechanism as an artifact source in ESR spin-trapping.

    PubMed

    Leinisch, Fabian; Ranguelova, Kalina; DeRose, Eugene F; Jiang, JinJie; Mason, Ronald P

    2011-12-19

    Nitrone spin traps such as 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) are commonly used for free radical detection. Though proven examples are rare, artifact formation must be considered. For example, the Forrester-Hepburn mechanism yields the same radical adduct as that formed by genuine radical trapping. A hydroxylamine is formed by nucleophilic attack of the substrate on DMPO and subsequently oxidized to the respective nitroxide radical. One potential candidate for this artifact is the sulfur trioxide radical adduct (DMPO/()SO(3)(-)), as detected in spin-trapping experiments with horseradish peroxidase and sulfite. It has previously been shown by NMR experiments that the hydroxylamine intermediate does indeed form, but no direct proof for the ESR artifact has been provided. Here, we used isotopically labeled DMPO with horseradish peroxidase and ferricyanide to test for the Forrester-Hepburn artifact directly in a spin-trapping experiment. Besides sulfite, we investigated other nucleophiles such as cyanide, cysteine, and glutathione. Neither sulfite nor biological thiols produced detectable spin-trapping artifacts, but with cyanide the relatively weak signal originated entirely from the nucleophilic reaction. The hydroxylamine intermediate, which is more abundant with cyanide than with sulfite, was identified as cyano-hydroxylamine by means of 2D NMR experiments. Although our study found that spin trapping provided authentic free radical signals with most of the substrates, the occurrence of the Forrester-Hepburn mechanism artifact with cyanide emphasizes the importance of isotope measurements with nucleophile substrates. PMID:22004308

  16. Microfabricated Surface-Electrode Ion Trap for Scalable Quantum Information Processing

    SciTech Connect

    Seidelin, S.; Chiaverini, J.; Reichle, R.; Bollinger, J.J.; Leibfried, D.; Britton, J.; Wesenberg, J.H.; Blakestad, R.B.; Epstein, R.J.; Hume, D.B.; Itano, W.M.; Jost, J.D.; Langer, C.; Ozeri, R.; Shiga, N.; Wineland, D.J.

    2006-06-30

    Individual laser-cooled {sup 24}Mg{sup +} ions are confined in a linear Paul trap with a novel geometry where gold electrodes are located in a single plane and the ions are trapped 40 {mu}m above this plane. The relatively simple trap design and fabrication procedure are important for large-scale quantum information processing (QIP) using ions. Measured ion motional frequencies are compared to simulations. Measurements of ion recooling after cooling is temporarily suspended yield a heating rate of approximately 5 motional quanta per millisecond for a trap frequency of 2.83 MHz, sufficiently low to be useful for QIP.

  17. Mechanism of DNA Trapping in Nanoporous Structures during Asymmetric Pulsed-Field Electrophoresis

    NASA Astrophysics Data System (ADS)

    Zhou, Ya; Harrison, D. Jed

    2014-03-01

    DNA molecules (>100kbp) are trapped in separation sieves when high electric fields are applied in pulsed field electrophoresis, seriously limiting the speed of separation. Using crystalline particle arrays, to generate interstitial pores for molecular sieving, allows higher electric fields than in gels, (e.g 40 vs 5 V/cm), however trapping still limits the field strength. Using reverse pulses, which release DNA from being fully-stretched, allows higher fields (140 V/cm). We investigate the trapping mechanism of individual DNA molecules in ordered nanoporous structures. Two prerequisites for trapping are revealed by the dynamics of single trapped DNA, hernia formation and fully-stretched U/J shapes. Fully stretched DNA has longer unhooking times than expected by simple models. We propose a dielectrophoretic (DEP) force reduces the mobility of segments at the apex of the U or J, where field gradients are highest, based on simulations. A modified model for unhooking time is obtained after the DEP force is introduced. The new model explains the unhooking time data by predicting an infinite trapping time when the ratio of arm length differences (of the U or J) to molecule length Δx / L < β . β is a DEP parameter that is found to strongly increase with electric field. The work was supported by grant from Natural Sciences and Engineering Research Council of Canada (NSERC) and the National Institute for Nanotechnology (NINT).

  18. Ion Sponge: A 3-Dimentional Array of Quadrupole Ion Traps for Trapping and Mass-Selectively Processing Ions in Gas Phase

    PubMed Central

    2015-01-01

    In this study, the concept of ion sponge has been explored for developing 3D arrays of large numbers of ion traps but with simple configurations. An ion sponge device with 484 trapping units in a volume of 10 × 10 × 3.2 cm has been constructed by simply stacking 9 meshes together. A single rf was used for trapping ions and mass-selective ion processing. The ion sponge provides a large trapping capacity and is highly transparent for transfer of ions, neutrals, and photons for gas phase ion processing. Multiple layers of quadrupole ion traps, with 121 trapping units in each layer, can operate as a single device for MS or MS/MS analysis, or as a series of mass-selective trapping devices with interlayer ion transfers facilitated by AC and DC voltages. Automatic sorting of ions to different trapping layers based on their mass-to-charge (m/z) ratios was achieved with traps of different sizes. Tandem-in-space MS/MS has also been demonstrated with precursor ions and fragment ions trapped in separate locations. PMID:24758328

  19. Ion sponge: a 3-dimentional array of quadrupole ion traps for trapping and mass-selectively processing ions in gas phase.

    PubMed

    Xu, Wei; Li, Linfan; Zhou, Xiaoyu; Ouyang, Zheng

    2014-05-01

    In this study, the concept of ion sponge has been explored for developing 3D arrays of large numbers of ion traps but with simple configurations. An ion sponge device with 484 trapping units in a volume of 10 × 10 × 3.2 cm has been constructed by simply stacking 9 meshes together. A single rf was used for trapping ions and mass-selective ion processing. The ion sponge provides a large trapping capacity and is highly transparent for transfer of ions, neutrals, and photons for gas phase ion processing. Multiple layers of quadrupole ion traps, with 121 trapping units in each layer, can operate as a single device for MS or MS/MS analysis, or as a series of mass-selective trapping devices with interlayer ion transfers facilitated by AC and DC voltages. Automatic sorting of ions to different trapping layers based on their mass-to-charge (m/z) ratios was achieved with traps of different sizes. Tandem-in-space MS/MS has also been demonstrated with precursor ions and fragment ions trapped in separate locations. PMID:24758328

  20. 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...

  1. Investigation of spin-trapping artifacts formed by the Forrester-Hepburn mechanism.

    PubMed

    Leinisch, Fabian; Jiang, Jinjie; DeRose, Eugene F; Khramtsov, Valery V; Mason, Ronald P

    2013-12-01

    Free radical detection with ESR spin trapping relies on the specific addition of the radical to nitrone/nitroso compounds. It also has been proposed that spin traps can react in biological systems to give false-positive results. For nitrone spin traps, the reaction with nucleophiles, first described by Forrester and Hepburn, has been discussed as the most critical source of artifacts. For artifact identification, the ESR preincubation method may be used, which employs isotopically marked spin traps. Here we investigated the influence of fast sulfite-hydroxylamine equilibrium chemistry on the validity of this assay. Using the (faster) aspiration technique, we found that the Forrester-Hepburn mechanism also contributes to DMPO/()SO3(-) adduct formation during ferricyanide-mediated sulfite oxidation, but no evidence for artifactual DMPO/()SO3(-) formation was found if the more potent horseradish peroxidase was used. This is ESR evidence that the Forrester-Hepburn mechanism can occur under mild conditions, depending on the experimental details. This technique can also be used to test for other artifact mechanisms. We investigated the known ene reaction of DBNBS and tryptophan in more detail. We found that a strong artifact signal is induced by light; however, with atypically long incubations, we found that the artifact is also formed thermally. PMID:23851031

  2. Investigation of Spin-Trapping Artifacts Formed by the Forrester-Hepburn Mechanism

    PubMed Central

    Jiang, Jinjie; DeRose, Eugene F.; Khramtsov, Valery V.; Mason, Ronald P.

    2013-01-01

    Free radical detection with ESR spin trapping relies on the specific addition of the radical to nitrone/nitroso compounds. It has been proposed that spin traps can react also in biological systems to give false-positive results. For nitrone spin traps, the reaction with nucleophiles, first described by Forrester and Hepburn, has been discussed as the most critical source of artifacts. For artifact identification, the ESR preincubation method may be used, which employs isotopically marked spin traps. Here we investigated the influence of fast sulfite-hydroxylamine equilibrium chemistry on the validity of this assay. Using the (faster) aspiration technique, we found that the Forrester-Hepburn mechanism also contributes to DMPO/•SO3– adduct formation during ferricyanide-mediated sulfite oxidation, but no evidence for artifactual DMPO/•SO3– formation was found if the more potent horseradish peroxidase was used. This is ESR evidence that the Forrester-Hepburn mechanism can occur under mild conditions, depending on the experimental details. This technique can also be used to test for other artifact mechanisms. We investigated the known ene reaction of DBNBS and tryptophan in more detail. We found that a strong artifact signal is induced by light; however, with atypically long incubations, we found that the artifact is also formed thermally. PMID:23851031

  3. Two size-selective mechanisms specifically trap bacteria-sized food particles in Caenorhabditis elegans.

    PubMed

    Fang-Yen, Christopher; Avery, Leon; Samuel, Aravinthan D T

    2009-11-24

    Caenorhabditis elegans is a filter feeder: it draws bacteria suspended in liquid into its pharynx, traps the bacteria, and ejects the liquid. How pharyngeal pumping simultaneously transports and filters food particles has been poorly understood. Here, we use high-speed video microscopy to define the detailed workings of pharyngeal mechanics. The buccal cavity and metastomal flaps regulate the flow of dense bacterial suspensions and exclude excessively large particles from entering the pharynx. A complex sequence of contractions and relaxations transports food particles in two successive trap stages before passage into the terminal bulb and intestine. Filtering occurs at each trap as bacteria are concentrated in the central lumen while fluids are expelled radially through three apical channels. Experiments with microspheres show that the C. elegans pharynx, in combination with the buccal cavity, is tuned to specifically catch and transport particles of a size range corresponding to most soil bacteria. PMID:19903886

  4. Surface-electrode ion traps and technologies for scalable quantum information processing

    NASA Astrophysics Data System (ADS)

    Doret, S.; Amini, Jason; Brown, Kenton; Shappert, Chris; Landgren, David; Ozakin, Arkadas; Hayden, Harley; Pai, C.-S.; Volin, Curtis; Lust, Lisa; Harter, Alexa

    2013-05-01

    As experiments in quantum information processing with trapped ions progress from few to many ion-qubits, it is imperative that trap designs and technologies keep pace. Surface-electrode traps offer one path to scaling experiments to large numbers of ions, but they will require the integration of many trapping zones and associated interconnects. We have developed a new trap (``Satellite'') with separated loading, storage, and computation regions connected by a newly-designed X-junction. The storage regions feature inter-digitated control electrodes, allowing storage of up to twenty ions in each zone with only a moderate increase in the trap's lead count. Even so, future traps of increasing complexity will create challenges for experimental control. With this in mind, we are developing in-vacuum electronics to reduce requirements for external control systems and simplify vacuum feedthrough requirements. We have also demonstrated co-trapping of 40Ca+/171Yb+ and are exploring strategies, both theoretically and experimentally, for sympathetic cooling of dual-species ion chains. In collaboration with Honeywell International.

  5. 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 maneuversinvolving what is thought, how it is thought, and how it is organizedmay 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

  6. On the mechanism of trap closure of Venus flytrap (Dionaea muscipula Ellis).

    PubMed

    Hodick, D; Sievers, A

    1989-08-01

    The rapid trap closure of Dionaea muscinula Ellis has been explained by either a loss of turgor pressure of the upper epidermis, which should thus become flexible, or by a sudden acid-induced wall loosening of the motor cells. According to our experiments both explanations are doubtful. Objections against the turgor mechanism come from the determination by extracellular measurements from the upper epidermis of action-potential amplitudes before and after trap closure. Neither time course nor amplitude of the action potentials are altered by trap closure. In contrast a rise in the apoplastic concentration of K(+) or Na(+), which are the only ions present in the trap in osmotically significant concentrations, from 1 to 10 mM reduces the action-potential amplitudes by 25% and 15%, respectively. Furthermore, after trap closure the upper epidermal cells retain a considerable cell sap osmolality of 0.41 molkg(-1) which equals that of the mesophyll cells as determined by incipient plasmolysis. A sudden cell-wall acidification causing movement is improbable since an acidification of the apoplast from pH 6 to pH 4 reduces action-potential amplitudes by 33% whereas the amplitudes measured extracellylarly from the mesophyll and lower epidermis remain unchanged by trap closure. In addition, buffering the apoplast at pH 6 does not prevent movement in traps which have been incised several times from the margin to the midrib to facilitate buffer diffusion into the mesophyll. Even an alkalinization of cell walls of plasmolysed leaf segments to pH 9 does not prevent considerable extensions of the mesophyll and subsequent movement of the specimens during deplasmolysis.These experiments make it very likely that the mesophyll cells are already extensible but are kept compressed in the open trap, thus developing tissue tension. The mechanism which prevents their extension as long as the trap is open can so far only be explained for traps which have been paralysed by a long-term incubation in 1 mM La(3+). Leaf strips taken from stimulated, closed traps, comprising the lower epidermis and some mesophyll, prove to be highly extensible if they are stretched perpendicular to the midrib on a constant-load extensiometer. By contrast, strips taken from the lower side of paralysed traps are as rigid as those from the upper side of both stimulated and paralysed traps. From observations of semithin cross sections in a polarizing microscope, it is concluded that the extensibilities of these tissue strips are mainly determined by the cell walls of the upper epidermis plus a layer of adjacent mesophyll and by the lower epidermis, respectively, since these are the only cell walls with a preferential microfibril orientation in the direction of the applied stress. PMID:24201419

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

    SciTech Connect

    Dubin, Daniel H. E.

    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.

  8. Trapping processes in CaS:Eu{sup 2+},Tm{sup 3+}

    SciTech Connect

    Jia, Dongdong; Jia, Weiyi; Evans, D. R.; Dennis, W. M.; Liu, Huimin; Zhu, Jing; Yen, W. M.

    2000-09-15

    CaS:Eu{sup 2+},Tm{sup 3+} is a persistent red phosphor. Thermoluminescence was measured under different excitation and thermal treatment conditions. The results reveal that the charge defects, created by substituting Tm{sup 3+} for Ca{sup 2+}, serve as hole traps for the afterglow at room temperature. Tm{sup 3+} plays the role of deep electron trapping centers, capturing electrons either through the conduction band or directly from the excited Eu{sup 2+} ions. These two processes, in which two different sites of Tm{sup 3+} are involved, correspond to two traps with different depths. (c) 2000 American Institute of Physics.

  9. 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.

  10. Quantum information processing and cavity QED experiments with trapped Ca+ ions

    NASA Astrophysics Data System (ADS)

    Gulde, S.; Hffner, H.; Riebe, M.; Lancaster, G.; Mundt, A.; Kreuter, A.; Russo, C.; Becher, C.; Eschner, J.; Schmidt-Kaler, F.; Chuang, I. L.; Blatt, R.

    2003-04-01

    Single trapped Ca+ ions, stored in a linear Paul trap and laser-cooled to the ground state of their harmonic quantum motion are used for quantum information processing. As a demonstration, composite laser pulse sequences were used to implement phase gate and CNOT gate operation. For this, Stark shifts on the qubit transitions were precisely measured and compensated. With a single ion stored inside a high-finesse optical cavity, a cavity mode can be coherently coupled to the qubit transition.

  11. The pollination mechanism in Trigonidium obtusum Lindl (Orchidaceae: Maxillariinae): sexual mimicry and trap-flowers.

    PubMed

    Singer, Rodrigo B

    2002-02-01

    The pollination process in Trigonidium obtusum Lindl. (Epidendroideae: Maxillariinae) is documented. The flowers are pollinated by sexually excited drones of Plebeia droryana (Meliponinae). When attempting to copulate either with sepals or petals, these bees slip on the waxy perianth surface and become trapped in the funnel-like flower tube. Bees trying to escape from the flowers may instead access the space between the column and lip, fixing the pollinarium on their scutellum. Pollinarium-bearing bees may pollinate the flowers when repeating the above-mentioned steps, leaving pollinia on the concave stigmatic surface, thus effecting pollination. Recently removed pollinaria are too broad to enter the stigma but they begin to dehydrate and within 40 min of removal are small enough to fit the stigmatic cavity. This mechanism prevents insect-mediated self-pollination and promotes cross-pollination. Preliminary evidence based on experiments with cultivated plants suggests that they are self-compatible but that fruit set is pollinator-dependent. The data obtained are discussed in a phylogenetic context. It is suggested that the pseudocopulatory syndrome in Trigonidium could have evolved from rewardless (food advertising) ancestors. Pseudocopulation in the context of the long flowering period of this orchid species (about 7 months) is understandable since the eusocial Plebeia bees produce fertile individuals several times a year. PMID:12099346

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

    SciTech Connect

    Parks, II, James E; Ponnusamy, Senthil

    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.

  13. Immuno-spin trapping of protein and DNA radicals: tagging free radicals to locate and understand the redox process

    PubMed Central

    Gomez-Mejiba, Sandra E.; Zhai, Zili; Akram, Hammad; Deterding, Leesa J.; Hensley, Kenneth; Smith, Nataliya; Towner, Rheal A.; Tomer, Kenneth B.; Mason, Ronald P.; Ramirez, Dario C.

    2009-01-01

    Biomolecule-centered radicals are intermediate species produced during both reversible (redox modulation) and irreversible (oxidative stress) oxidative modification of biomolecules. These oxidative processes must be studied in situ and in real time in order to understand the molecular mechanism of cell adaptation or death in response to changes in the extracellular environment. In this regard, we have developed and validated immuno-spin trapping to tag the redox process, tracing the oxidatively-generated modification of biomolecules, in situ and in real time, by detecting protein- and DNA-centered radicals. The purpose of this method article is to introduce and update the basic methods and applications of immuno-spin trapping for the study of redox biochemistry in oxidative stress and redox regulation. We describe in detail the production, detection and location of protein and DNA radicals in biochemical systems, cells, and tissues, and in the whole animal as well, by using immuno-spin trapping with the nitrone spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO). PMID:19159679

  14. With a Flick of the Lid: A Novel Trapping Mechanism in Nepenthes gracilis Pitcher Plants

    PubMed Central

    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

  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. 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

  17. Imaging of Trapped Ions with a Microfabricated Optic for Quantum Information Processing

    NASA Astrophysics Data System (ADS)

    Streed, Erik W.; Norton, Benjamin G.; Jechow, Andreas; Weinhold, Till J.; Kielpinski, David

    2011-01-01

    Trapped ions are a leading system for realizing quantum information processing (QIP). Most of the technologies required for implementing large-scale trapped-ion QIP have been demonstrated, with one key exception: a massively parallel ion-photon interconnect. Arrays of microfabricated phase Fresnel lenses (PFL) are a promising interconnect solution that is readily integrated with ion trap arrays for large-scale QIP. Here we show the first imaging of trapped ions with a microfabricated in-vacuum PFL, demonstrating performance suitable for scalable QIP. A single ion fluorescence collection efficiency of 4.21.5% was observed. The depth of focus for the imaging system was 19.42.4?m and the field of view was 14020?m. Our approach also provides an integrated solution for high-efficiency optical coupling in neutral atom and solid-state QIP architectures.

  18. Long persistent and optically stimulated luminescence behaviors of calcium aluminates with different trap filling processes

    NASA Astrophysics Data System (ADS)

    Zhang, Buhao; Xu, Xuhui; Li, Qianyue; Wu, Yumei; Qiu, Jianbei; Yu, Xue

    2014-09-01

    Properties of long persistent luminescence (LPL) and optically stimulated luminescence (OSL) of CaAl2O4:Eu2+, R3+ (R=Nd, Dy, Tm) materials were investigated. The observed phenomenon indicates that R3+ ions (R=Nd, Dy, Tm) have different effects on trap properties of CaAl2O4:Eu2+. The greatly improved LPL performance was observed in Nd3+ co-doped samples, which indicates that the incorporation of Nd3+ creates suitable traps for LPL. While co-doping Tm3+ ions, the intensity of high temperature of thermoluminescence band in CaAl2O4:Eu2+ phosphors is enhanced for the formation of the most suitable traps which benefits the intense and stable OSL. These results suggest that the effective traps contributed to the LPL/OSL are complex, of which could be an aggregation formation with shallow and deep traps other than simple traps from co-doped R3+ ions. The mechanism presented in the end potentially provides explanations of why the OSL of CaAl2O4:Eu2+, R3+ exhibits different read-in/read-out performance as well.

  19. Trapping toxins within lipid droplets is a resistance mechanism in fungi

    PubMed Central

    Chang, Wenqiang; Zhang, Ming; Zheng, Sha; Li, Ying; Li, Xiaobin; Li, Wei; Li, Gang; Lin, Zhaomin; Xie, Zhiyu; Zhao, Zuntian; Lou, Hongxiang

    2015-01-01

    Lipid droplets (LDs) act as intracellular storage organelles in most types of cells and are principally involved in energy homeostasis and lipid metabolism. However, the role of LDs in resistance to toxins in fungi remains largely unknown. Here, we show that the trapping of endogenous toxins by LDs is a self-resistance mechanism in the toxin producer, while absorbing external lipophilic toxins is a resistance mechanism in the toxin recipient that acts to quench the production of reactive oxygen species. We found that an endolichenic fungus that generates phototoxic perylenequinones (PQs) trapped the PQs inside LDs. Using a model that incorporates the fungicidal action of hypocrellin A (HA), a PQ derivative, we showed that yeast cells escaped killing by trapping toxins inside LDs. Furthermore, LD-deficient mutants were hypersusceptible to HA-mediated phototoxins and other fungicides. Our study identified a previously unrecognised function of LDs in fungi that has implications for our understanding of environmental adaptation strategies for fungi and antifungal drug discovery. PMID:26463663

  20. Trapping toxins within lipid droplets is a resistance mechanism in fungi.

    PubMed

    Chang, Wenqiang; Zhang, Ming; Zheng, Sha; Li, Ying; Li, Xiaobin; Li, Wei; Li, Gang; Lin, Zhaomin; Xie, Zhiyu; Zhao, Zuntian; Lou, Hongxiang

    2015-01-01

    Lipid droplets (LDs) act as intracellular storage organelles in most types of cells and are principally involved in energy homeostasis and lipid metabolism. However, the role of LDs in resistance to toxins in fungi remains largely unknown. Here, we show that the trapping of endogenous toxins by LDs is a self-resistance mechanism in the toxin producer, while absorbing external lipophilic toxins is a resistance mechanism in the toxin recipient that acts to quench the production of reactive oxygen species. We found that an endolichenic fungus that generates phototoxic perylenequinones (PQs) trapped the PQs inside LDs. Using a model that incorporates the fungicidal action of hypocrellin A (HA), a PQ derivative, we showed that yeast cells escaped killing by trapping toxins inside LDs. Furthermore, LD-deficient mutants were hypersusceptible to HA-mediated phototoxins and other fungicides. Our study identified a previously unrecognised function of LDs in fungi that has implications for our understanding of environmental adaptation strategies for fungi and antifungal drug discovery. PMID:26463663

  1. Chemically assisted mechanical refrigeration process

    DOEpatents

    Vobach, A.R.

    1987-11-24

    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 at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer 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 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. 5 figs.

  2. Chemically assisted mechanical refrigeration process

    DOEpatents

    Vobach, Arnold R.

    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.

  3. Chemically assisted mechanical refrigeration process

    DOEpatents

    Vobach, A.R.

    1987-06-23

    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 at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer 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 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. 5 figs.

  4. Chemically assisted mechanical refrigeration process

    DOEpatents

    Vobach, Arnold R.

    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.

  5. The mechanics of manufacturing processes

    SciTech Connect

    Wright, P.; Stori, J.; King, C.

    1996-10-01

    Economic pressures, particularly related to the quality of manufactured goods and `time-to-market` are forcing designers to think not only in terms of product design but also in terms of integrated product and process design, and finally in terms of deterministic manufacturing planning and control. As a result of these three high level needs, there is now an even greater need for comprehensive simulations that predict material behavior during a manufacturing process, the stresses and/or temperatures on associated tooling, and the final-product integrity. The phrase `manufacturing processes` of course covers a broad scope; it includes semiconductor manufacturing, injection molding of polymers, metal machining and precision lapping, wood and textile production, and the final assembly of piece-parts into a consumer product. It can be seen from this partial listing that the fields of fluid mechanics, solid mechanics, dynamics and tribology can all play a role. The introduction to the paper will contain a review of manufacturing processes and describe where simulations have been successfully applied, and where simulations are still lacking. The best of the simulations are those where the models accurately fit the physical phenomena, where accurate constitutive equations are available, and where boundary conditions are realistic. Thus, the body of the paper will focus on the results from one of these more successful simulations. It has been used to predict the deflections of tooling and the most appropriate operating conditions for the manufacturing process under study. A new method for manufacturing planning is described. In this method, closed form, somewhat simplified, analytical models are used to determine manufacturing planning parameters and then the results from these simpler models are refined by the fuller simulations. A case study in machining parameter selection for peripheral finish milling operations is developed.

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

    SciTech Connect

    Thilagam, A.

    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.

  7. Fast electron accumulation and its mechanism in a harmonic trap under ultrahigh vacuum conditions

    SciTech Connect

    Mohamed, T.; Imao, H.; Mohri, A.; Oshima, N.; Yamazaki, Y.

    2011-03-15

    We present here a fast and efficient electron accumulation in a multiring trap (MRT) in a superconducting solenoid of 5 T. More than 10{sup 10} electrons were accumulated within a fraction of a second for an electron beam in the range of 10{sup -7} A. The MRT was installed in a cryogenic bore tube cooled down to {approx}10 K. Electron accumulation as a function of various parameters such as the beam intensity, the MRT depth, and the MRT length was studied. We succeeded in extracting a consistent picture of the electron accumulation mechanisms, which consist of interactions of the incoming electron beam with the reflected beam and with the electrons trapped in the MRT.

  8. 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.

  9. Experimental Investigation of CO2 Trapping and Leakage Mechanisms in Deep Geologic Formations for Model Improvement

    NASA Astrophysics Data System (ADS)

    Illangasekare, T. H.; Trevisan, L.; Agartan, E.; Vargas-Johnson, J.; Plampin, M. R.; Pini, R.; Pawar, R.; Cihan, A.; Birkholzer, J. T.; Zhou, Q.

    2014-12-01

    A fundamental and a comprehensive understanding of trapping and leakage processes will be of value to develop strategies for efficient and secure storage of CO2 in deep geologic formations and assess environmental and ecological risks associated with potential leakage. It is our contention that to make observations and collect data to obtain a fundamental understanding of how the natural formation heterogeneity manifested at all scales affects trapping is highly challenging or impossible to obtain in real field settings in deep geologic formations. A test scale intermediary between small laboratory columns and field scales that is referred to as "intermediate scale" provides an attractive alternative to investigate these processes under controlled conditions in the laboratory. Heterogeneities at all needed test scales can be designed using soils with known properties and experiments can be conducted under controlled conditions to obtain accurate data. Conducting intermediate scale laboratory experiments under ambient pressure and temperature conditions to understand the processes that occur in deep formations with very higher pressures and drastically different temperatures pose many challenges. This paper presents the approaches that were used to conduct multi-scale experiments from column to intermediate scale to understand the factors that contribute to capillary and dissolution trapping using surrogate fluids for supercritical CO2 and saline water combination. In addition, experiments were conducted in soil columns and two-dimensional tanks to study the effects of formation heterogeneity on CO2 gas evolution during leakage of water with dissolved CO2. The results from these experiments are presented to show how the new insights have helped to improve the conceptual understanding of effects of heterogeneity on CO2 trapping and leakage. This understanding has helped to improve numerical models that can be used to better engineer CO2 storage systems for permanence and evaluate possible failure risks.

  10. Electrolytic trapping of iodine from process gas streams

    DOEpatents

    Horner, Donald E.; Mailen, James C.; Posey, Franz A.

    1977-01-25

    A method for removing molecular, inorganic, and organic forms of iodine from process gas streams comprises the electrolytic oxidation of iodine in the presence of cobalt-III ions. The gas stream is passed through the anode compartment of a partitioned electrolytic cell having a nitric acid anolyte containing a catalytic amount of cobalt to cause the oxidation of effluent iodine species to aqueous soluble species.

  11. Motor protein and microtubule mechanics: Application of a novel high-resolution optical trapping technique

    NASA Astrophysics Data System (ADS)

    Allersma, Miriam W.

    Using optical tweezers and a novel detection technique (a quadrant photodiode at the back focal plane or, BFP-QD), this thesis investigates two problems in biophysics, ncd motility and microtubule flexural rigidity. We use optically trapped microspheres to probe the samples. The technique detects the displacements of the microspheres relative to the trap center by monitoring the laser intensity shifts in the back focal plane of the microscope condenser. We use a quadrant diode to detect the shifts, which are due to far-field interference between the trapping laser and scattered laser light from the trapped object. The method yields high-resolution (nm-spatial and ?sec-temporal), two-dimensional data, which is largely independent of trap position in the field of view. We first studied the motility of ncd, a kinesin-related motor protein. Motor proteins are able to harness the energy of ATP hydrolysis to perform mechanical work for the cell. Many ncd molecules were adsorbed onto silica microspheres and their motions along the microtubule surface lattice were observed with the BFP-QD method. Since the method is two-dimensional, we were able to monitor axial and lateral motions simultaneously. The average axial velocity was 230 +/- 30 nm/sec (average +/- SD). The high temporal resolution allowed us to investigate dynamical parameters. Spectral analysis showed an increase in viscous drag near the surface for ncd-driven microspheres. In addition, we found that the binding of the motors to microtubules in the presence of the nonhydrolyzable nucleotide adenylylimidodiphosphate caused an increase in the motor elastic constraint. Using a dual optical trap configuration in conjunction with the BFP-QD, we also investigated the elastic properties of taxol-stabilized microtubules. Cytoskeletal filaments are responsible for myriad structural cell functions. Our results were not readily interpreted by a standard bent strut treatment because of the finite size of the microspheres used as probes. I calculated an extension to the regular theory, which proved promising. The flexural rigidity was 3.2 +/- 1.0 pN?m2 which is consistent with other results in the literature.

  12. Contrast mechanism due to interface trapped charges for a buried SiO2 microstructure in scanning electron microscopy.

    PubMed

    Zhang, Hai-Bo; Li, Wei-Qin; Wu, Dan-Wei

    2009-01-01

    We clarify the scanning electron microscopic contrast mechanism for imaging a buried SiO(2) trench microstructure with interface trapped charges by simulating both electron scattering and transport. Here, the interface trapped charges make the SiO(2) film more negatively charged and increase excess holes in the space charge distribution of the electron scattering region. The generated positive surface electric field thus redistributes some emitted secondary electrons and results in the dark contrast. This contrast mechanism is validated by comparing with experiments, and it may also provide an interesting approach for imaging and detecting deep interface trapped charges in insulating films. PMID:19029106

  13. Quantum-mechanical engines working with an ideal gas with a finite number of particles confined in a power-law trap

    NASA Astrophysics Data System (ADS)

    Wang, Jianhui; Ma, Yongli; He, Jizhou

    2015-07-01

    Based on quantum thermodynamic processes, we make a quantum-mechanical (QM) extension of the typical heat engine cycles, such as the Carnot, Brayton, Otto, Diesel cycles, etc., with no introduction of the concept of temperature. When these QM engine cycles are implemented by an ideal gas confined in an arbitrary power-law trap, a relation between the quantum adiabatic exponent and trap exponent is found. The differences and similarities between the efficiency of a given QM engine cycle and its classical counterpart are revealed and discussed.

  14. 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

  15. Technical Note: Sampling and processing of mesocosm sediment trap material for quantitative biogeochemical analysis

    NASA Astrophysics Data System (ADS)

    Boxhammer, T.; Bach, L. T.; Czerny, J.; Riebesell, U.

    2015-11-01

    Sediment traps are the most common tool to investigate vertical particle flux in the marine realm. However, the spatial decoupling between particle formation and collection often handicaps reconciliation of these two processes even within the euphotic zone. Pelagic mesocosms have the advantage of being closed systems and are therefore ideally suited to study how processes in natural plankton communities influence particle formation and settling in the ocean's surface. We therefore developed a protocol for efficient sample recovery and processing of quantitatively collected pelagic mesocosm sediment trap samples. Sedimented material was recovered by pumping it under gentle vacuum through a silicon tube to the sea surface. The particulate matter of these samples was subsequently concentrated by passive settling, centrifugation or flocculation with ferric chloride and we discuss the advantages of each approach. After concentration, samples were freeze-dried and ground with an easy to adapt procedure using standard lab equipment. Grain size of the finely ground samples ranges from fine to coarse silt (2-63 μm), which guarantees homogeneity for representative subsampling, a widespread problem in sediment trap research. Subsamples of the ground material were perfectly suitable for a variety of biogeochemical measurements and even at very low particle fluxes we were able to get a detailed insight on various parameters characterizing the sinking particles. The methods and recommendations described here are a key improvement for sediment trap applications in mesocosms, as they facilitate processing of large amounts of samples and allow for high-quality biogeochemical flux data.

  16. Mathematical Modeling of Ultracold Few-Body Processes in Atomic Traps

    NASA Astrophysics Data System (ADS)

    Melezhik, V. S.

    2016-02-01

    We discuss computational aspects of the developed mathematical models for ultracold few-body processes in atomic traps. The key element of the elaborated computational schemes is a nondirect product discrete variable representation (npDVR) we have suggested and applied to the time-dependent and stationary Schrödinger equations with a few spatial variables. It turned out that this approach is very effcient in quantitative analysis of low-dimensional ultracold few-body systems arising in confined geometry of atomic traps. The effciency of the method is demonstrated here on two examples. A brief review is also given of novel results obtained recently.

  17. Dynamical processes in Rydberg-Stark deceleration and trapping of atoms and molecules.

    PubMed

    Seiler, Christian; Hogan, Stephen D; Merkt, Frdric

    2012-01-01

    The interaction between inhomogeneous electric fields and the large electric dipole moments of atoms and molecules in Rydberg states of high principal quantum number can be used to efficiently accelerate and decelerate atoms and molecules in the gas phase. We describe here how hydrogen atoms and molecules initially moving with velocities of ?600 m/s in supersonic beams can be decelerated to zero velocity and loaded into electric traps. The long observation times that are made possible by the electrostatic trapping enables one to study slow relaxation processes. Experiments are presented in which we have observed photoionization processes and transitions between Rydberg states induced by blackbody radiation at temperatures between 10 K and 300 K on a time scale of several milliseconds. Comparison of these processes in Rydberg states of H and H(2) suggests the importance, in H(2), of collisional processes and of the process of blackbody-radiation-induced predissociation. PMID:22613151

  18. Membrane-Based Gas Traps for Ammonia, Freon-21, and Water Systems to Simplify Ground Processing

    NASA Technical Reports Server (NTRS)

    Ritchie, Stephen M. C.

    2003-01-01

    Gas traps are critical for the smooth operation of coolant loops because gas bubbles can cause loss of centrifugal pump prime, interference with sensor readings, inhibition of heat transfer, and blockage of passages to remote systems. Coolant loops are ubiquitous in space flight hardware, and thus there is a great need for this technology. Conventional gas traps will not function in micro-gravity due to the absence of buoyancy forces. Therefore, clever designs that make use of adhesion and momentum are required for adequate separation, preferable in a single pass. The gas traps currently used in water coolant loops on the International Space Station are composed of membrane tube sets in a shell. Each tube set is composed of a hydrophilic membrane (used for water transport and capture of bubbles) and a hydrophobic membrane (used for venting of air bubbles). For the hydrophilic membrane, there are two critical pressures, the pressure drop and the bubble pressure. The pressure drop is the decrease in system pressure across the gas trap. The bubble pressure is the pressure required for air bubbles to pass across the water filled membrane. A significant difference between these pressures is needed to ensure complete capture of air bubbles in a single pass. Bubbles trapped by the device adsorb on the hydrophobic membrane in the interior of the hydrophilic membrane tube. After adsorption, the air is vented due to a pressure drop of approximately 1 atmosphere across the membrane. For water systems, the air is vented to the ambient (cabin). Because water vapor can also transport across the hydrophobic membrane, it is critical that a minimum surface area is used to avoid excessive water loss (would like to have a closed loop for the coolant). The currently used gas traps only provide a difference in pressure drop and bubble pressure of 3-4 psid. This makes the gas traps susceptible to failure at high bubble loading and if gas venting is impaired. One mechanism for the latter is when particles adhere to the hydrophobic membrane, promoting formation of a water layer about it that can blind the membrane for gas transport (Figure 1). This mechanism is the most probable cause for observed failures with the existing design. The objective of this project was to devise a strategy for choosing new membrane materials (database development and procedure), redesign of the gas trap to mitigate blinding effects, and to develop a design that can be used in ammonia and Freon-21 coolant loops.

  19. Defining brain wiring patterns and mechanisms through gene trapping in mice.

    PubMed

    Leighton, P A; Mitchell, K J; Goodrich, L V; Lu, X; Pinson, K; Scherz, P; Skarnes, W C; Tessier-Lavigne, M

    2001-03-01

    The search to understand the mechanisms regulating brain wiring has relied on biochemical purification approaches in vertebrates and genetic approaches in invertebrates to identify molecular cues and receptors for axon guidance. Here we describe a phenotype-based gene-trap screen in mice designed for the large-scale identification of genes controlling the formation of the trillions of connections in the mammalian brain. The method incorporates an axonal marker, which helps to identify cell-autonomous mechanisms in axon guidance, and has generated a resource of mouse lines with striking patterns of axonal labelling, which facilitates analysis of the normal wiring diagram of the brain. Studies of two of these mouse lines have identified an in vivo guidance function for a vertebrate transmembrane semaphorin, Sema6A, and have helped re-evaluate that of the Eph receptor EphA4. PMID:11242070

  20. 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

  1. 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...

  2. Mechanism of follicular trapping: double immunocytochemical evidence for a contribution of locally produced antibodies in follicular trapping of immune complexes.

    PubMed Central

    van Rooijen, N; Kors, N

    1985-01-01

    Using two different antigen-enzyme conjugates and a double immunocytochemical staining technique, we demonstrate the localization patterns of two different specific antibodies in the same spleen section. During the early immune responses against simultaneously injected human gamma globulin (HGG), and bovine gamma globulin (BGG) in rabbits, the localization patterns of extracellular anti-HGG antibodies and extracellular anti-BGG antibodies in the follicles overlap only partly. It was shown in earlier studies that extracellular antibodies trapped in the follicles represent antigen-antibody complexes having free binding sites for the antigen. The fact that localization patterns do not overlap extensively, whereas it has been shown in earlier studies that follicular dendritic cells (FDCs) show no specificity with respect to the immune complexes to be captured, leads to the following conclusion. After formation of immune complexes from antibody molecules released by specific antibody-forming cells in the follicles and antigen present in excess between the cells, part of these complexes are trapped by adjacent FDCs. Results are discussed with respect to the possible role of follicular immune complexes in the generation of immunological memory. Images Figure 1 PMID:2581888

  3. A novel method to reduce time investment when processing videos from camera trap studies.

    PubMed

    Swinnen, Kristijn R R; Reijniers, Jonas; Breno, Matteo; Leirs, Herwig

    2014-01-01

    Camera traps have proven very useful in ecological, conservation and behavioral research. Camera traps non-invasively record presence and behavior of animals in their natural environment. Since the introduction of digital cameras, large amounts of data can be stored. Unfortunately, processing protocols did not evolve as fast as the technical capabilities of the cameras. We used camera traps to record videos of Eurasian beavers (Castor fiber). However, a large number of recordings did not contain the target species, but instead empty recordings or other species (together non-target recordings), making the removal of these recordings unacceptably time consuming. In this paper we propose a method to partially eliminate non-target recordings without having to watch the recordings, in order to reduce workload. Discrimination between recordings of target species and non-target recordings was based on detecting variation (changes in pixel values from frame to frame) in the recordings. Because of the size of the target species, we supposed that recordings with the target species contain on average much more movements than non-target recordings. Two different filter methods were tested and compared. We show that a partial discrimination can be made between target and non-target recordings based on variation in pixel values and that environmental conditions and filter methods influence the amount of non-target recordings that can be identified and discarded. By allowing a loss of 5% to 20% of recordings containing the target species, in ideal circumstances, 53% to 76% of non-target recordings can be identified and discarded. We conclude that adding an extra processing step in the camera trap protocol can result in large time savings. Since we are convinced that the use of camera traps will become increasingly important in the future, this filter method can benefit many researchers, using it in different contexts across the globe, on both videos and photographs. PMID:24918777

  4. A Novel Method to Reduce Time Investment When Processing Videos from Camera Trap Studies

    PubMed Central

    Swinnen, Kristijn R. R.; Reijniers, Jonas; Breno, Matteo; Leirs, Herwig

    2014-01-01

    Camera traps have proven very useful in ecological, conservation and behavioral research. Camera traps non-invasively record presence and behavior of animals in their natural environment. Since the introduction of digital cameras, large amounts of data can be stored. Unfortunately, processing protocols did not evolve as fast as the technical capabilities of the cameras. We used camera traps to record videos of Eurasian beavers (Castor fiber). However, a large number of recordings did not contain the target species, but instead empty recordings or other species (together non-target recordings), making the removal of these recordings unacceptably time consuming. In this paper we propose a method to partially eliminate non-target recordings without having to watch the recordings, in order to reduce workload. Discrimination between recordings of target species and non-target recordings was based on detecting variation (changes in pixel values from frame to frame) in the recordings. Because of the size of the target species, we supposed that recordings with the target species contain on average much more movements than non-target recordings. Two different filter methods were tested and compared. We show that a partial discrimination can be made between target and non-target recordings based on variation in pixel values and that environmental conditions and filter methods influence the amount of non-target recordings that can be identified and discarded. By allowing a loss of 5% to 20% of recordings containing the target species, in ideal circumstances, 53% to 76% of non-target recordings can be identified and discarded. We conclude that adding an extra processing step in the camera trap protocol can result in large time savings. Since we are convinced that the use of camera traps will become increasingly important in the future, this filter method can benefit many researchers, using it in different contexts across the globe, on both videos and photographs. PMID:24918777

  5. Long persistent and optically stimulated luminescence behaviors of calcium aluminates with different trap filling processes

    SciTech Connect

    Zhang, Buhao; Xu, Xuhui; Li, Qianyue; Wu, Yumei; Qiu, Jianbei; Yu, Xue

    2014-09-15

    Properties of long persistent luminescence (LPL) and optically stimulated luminescence (OSL) of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} (R=Nd, Dy, Tm) materials were investigated. The observed phenomenon indicates that R{sup 3+} ions (R=Nd, Dy, Tm) have different effects on trap properties of CaAl{sub 2}O{sub 4}:Eu{sup 2+}. The greatly improved LPL performance was observed in Nd{sup 3+} co-doped samples, which indicates that the incorporation of Nd{sup 3+} creates suitable traps for LPL. While co-doping Tm{sup 3+} ions, the intensity of high temperature of thermoluminescence band in CaAl{sub 2}O{sub 4}:Eu{sup 2+} phosphors is enhanced for the formation of the most suitable traps which benefits the intense and stable OSL. These results suggest that the effective traps contributed to the LPL/OSL are complex, of which could be an aggregation formation with shallow and deep traps other than simple traps from co-doped R{sup 3+} ions. The mechanism presented in the end potentially provides explanations of why the OSL of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} exhibits different read-in/read-out performance as well. - Graphical abstract: OSL emission spectra of Ca{sub 0.995}Al{sub 2}O{sub 4}:0.0025Eu{sup 2+}, 0.0025R{sup 3+} (R=Nd, Dy, Tm) taken under varying stimulation time (0, 25, 50, 75, 100 s). Inset: Blue emission pictures under varying stimulation time. - Highlights: The LPL and OSL properties of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} were investigated. An alternative approach to control the trap depth of CaAl{sub 2}O{sub 4}:Eu{sup 2+} phosphor was proposed. A new oxide ETM phosphor exhibiting intense and stable OSL was explored.

  6. Current collection by a spherical high voltage probe: Electron trapping and collective processes

    NASA Technical Reports Server (NTRS)

    Palmadesso, Peter J.

    1990-01-01

    The author summarizes the results of theoretical studies of the interaction of an uninsulated, spherical, high voltage (10's of KV positive) probe with the ionospheric environment. The focus of this effort was the phenomenon of electron trapping and its implications for breakdown processes (collisional regime) and the current-voltage relationship governing current collection (collisionless regime) in space-based pulsed power systems with high voltage components exposed to space, e.g., the SPEAR I experiment.

  7. Stability and spacial trap state distribution of solution processed ZnO-thin film transistors

    NASA Astrophysics Data System (ADS)

    Ortel, Marlis; Pittner, Steve; Wagner, Veit

    2013-04-01

    Solution processed zinc oxide thin film transistors (TFTs) were investigated for spacial identification of instability inducing electronic trap states by utilizing surface-to-active-channel distance dependent analysis. It is shown that the performance and stability of zinc oxide TFTs deposited by spray pyrolysis strongly depend on the surface-to-channel distance and herewith on the film thickness in the investigated regime from 1 nm to 30 nm. In thin layers, the charge transport process is dominated by the number of percolation paths and near channel trapping processes due to coulomb interactions with surface charges. This leads to a high thickness of 3 nm for the percolation threshold. As soon as a closed layer is formed and the charge separation of 7 nm between surface and active channel is exceeded, bulk properties become more dominant. A maximum linear mobility of 11cm2 V-1 s-1 and an on-set voltage of 2 V were obtained for a film thickness of 30 nm. An increase of the film thickness from 10 nm to 30 nm leads to a reduction in the trap rate by one order of magnitude from 4.3 × 108 cm-2 s-1 to 3.7 × 107 cm-2 s-1. Due to this, the bias stress stability and the long term storage stability were found to improve significantly.

  8. Fostered Thermomagnetic Stabilities and Boosted Mechanical Reliability Related to High Trapped Field in Composite Bulk YBa2Cu3O(7-?) Cryomagnets.

    PubMed

    Kenfaui, Driss; Sibeud, Pierre-Frdric; Gomina, Moussa; Louradour, Eric; Chaud, Xavier; Noudem, Jacques G

    2015-08-01

    In the quest of YBa2Cu3O(7-?) (Y123) bulk superconductors providing strong magnetic fields without failure, it is of paramount importance to achieve high thermal stabilities to safeguard the magnetic energy inside them during the trapping-field process, and sufficient mechanical reliability to withstand the stresses derived from the Lorenz force. Herein, we experimentally demonstrate a temperature rise induced by dissipative flux motion inside an Y123 thin-wall superconductor, and a significant thermal exchange in a composite bulk Y123 cryomagnet realized by embedding this superconductor with high thermal-conductivity metal network. It resulted in stimulating the maximum trapped field Bm, which reached 6.46 T on 15.9 mm-diameter single disk superconductor after magnetization by field cooling to 17 K under 7 T, leading to an improvement of 18% compared to the thin-wall superconductor. The composite cryomagnet particularly revealed the potential to trap stronger fields if larger magnetic activation is available. By virtue of the pore-free and crack-free microstructure of this cryomagnet, its strength ?R was estimated to be 363 MPa, the largest one obtained so far for Y123 bulk superconductors, thus suggesting a striking mechanical reliability that seems to be sufficient to sustain stresses derived from trapped fields stronger than any values hitherto reported. PMID:26267194

  9. Spatially Non-uniform Trap State Densities in Solution-Processed Hybrid Perovskite Thin Films.

    PubMed

    Draguta, Sergiu; Thakur, Siddharatha; Morozov, Yurii V; Wang, Yuanxing; Manser, Joseph S; Kamat, Prashant V; Kuno, Masaru

    2016-02-18

    The facile solution-processability of methylammonium lead halide (CH3NH3PbI3) perovskites has catalyzed the development of inexpensive, hybrid perovskite-based optoelectronics. It is apparent, though, that solution-processed CH3NH3PbI3 films possess local emission heterogeneities, stemming from electronic disorder in the material. Herein we investigate the spatially resolved emission properties of CH3NH3PbI3 thin films through detailed emission intensity versus excitation intensity measurements. These studies enable us to establish the existence of nonuniform trap density variations wherein regions of CH3NH3PbI3 films exhibit effective free carrier recombination while others exhibit emission dynamics strongly influenced by the presence of trap states. Such trap density variations lead to spatially varying emission quantum yields and correspondingly impact the performance of both methylammonium lead halide perovskite solar cells and other hybrid perovskite-based devices. Of additional note is that the observed spatial extent of the optical disorder extends over length scales greater than that of underlying crystalline domains, suggesting the existence of other factors, beyond grain boundary-related nonradiative recombination channels, which lead to significant intrafilm optical heterogeneities. PMID:26840877

  10. Quantification of CO2 trapping through free convection process in isothermal brine saturated reservoir

    NASA Astrophysics Data System (ADS)

    Sun, A.; Islam, A.

    2014-12-01

    Dissolution trapping of supercritical CO2 into formation brine has been touted as a mechanism for reducing buoyancy force in carbon storage formations. This study attempts to quantify exactly how much CO2 can be stored through dissolution trapping assuming the free CO2 will be dissolved continuously on the top of perturbed brine phase. To our knowledge, most former investigations focused on physical explanations of density-driven free convection instability. Our aim is to compute the amount of CO2 (by mass) captured by dissolution trapping until the model reservoir reaches steady state. The numerical experimentation is done using dimensionless mass and momentum conservation laws. Reservoir is impervious from both sides and bottom, only open to CO2 at the top. The major problem parameter here is the solutal Rayleigh number of which we carry out an extensive survey to find out low and high ends based on real field data. Because density difference is the main driving force, we also investigate the effects of possible impurities retained in CO2 stream and the resulting effect on density contrast. We study results of both homogeneous and heterogeneous permeable reservoirs. Also, computations of zero gradient and zero flow boundary conditions are compared to understand the boundary effects. In all cases we set to run simulations for extended period of times (> 20,000 years) to achieve conclusive results.

  11. Intermediate Scale Laboratory Testing to Understand Mechanisms of Capillary and Dissolution Trapping during Injection and Post-Injection of CO2 in Heterogeneous Geological Formations

    SciTech Connect

    Illangasekare, Tissa; Trevisan, Luca; Agartan, Elif; Mori, Hiroko; Vargas-Johnson, Javier; González-Nicolás, Ana; Cihan, Abdullah; Birkholzer, Jens; Zhou, Quanlin

    2015-03-31

    Carbon Capture and Storage (CCS) represents a technology aimed to reduce atmospheric loading of CO2 from power plants and heavy industries by injecting it into deep geological formations, such as saline aquifers. A number of trapping mechanisms contribute to effective and secure storage of the injected CO2 in supercritical fluid phase (scCO2) in the formation over the long term. The primary trapping mechanisms are structural, residual, dissolution and mineralization. Knowledge gaps exist on how the heterogeneity of the formation manifested at all scales from the pore to the site scales affects trapping and parameterization of contributing mechanisms in models. An experimental and modeling study was conducted to fill these knowledge gaps. Experimental investigation of fundamental processes and mechanisms in field settings is not possible as it is not feasible to fully characterize the geologic heterogeneity at all relevant scales and gathering data on migration, trapping and dissolution of scCO2. Laboratory experiments using scCO2 under ambient conditions are also not feasible as it is technically challenging and cost prohibitive to develop large, two- or three-dimensional test systems with controlled high pressures to keep the scCO2 as a liquid. Hence, an innovative approach that used surrogate fluids in place of scCO2 and formation brine in multi-scale, synthetic aquifers test systems ranging in scales from centimeter to meter scale developed used. New modeling algorithms were developed to capture the processes controlled by the formation heterogeneity, and they were tested using the data from the laboratory test systems. The results and findings are expected to contribute toward better conceptual models, future improvements to DOE numerical codes, more accurate assessment of storage capacities, and optimized placement strategies. This report presents the experimental and modeling methods and research results.

  12. Insect Biometrics: Optoacoustic Signal Processing and Its Applications to Remote Monitoring of McPhail Type Traps.

    PubMed

    Potamitis, Ilyas; Rigakis, Iraklis; Fysarakis, Konstantinos

    2015-01-01

    Monitoring traps are important components of integrated pest management applied against important fruit fly pests, including Bactrocera oleae (Gmelin) and Ceratitis capitata (Widemann), Diptera of the Tephritidae family, which effect a crop-loss/per year calculated in billions of euros worldwide. Pests can be controlled with ground pesticide sprays, the efficiency of which depends on knowing the time, location and extent of infestations as early as possible. Trap inspection is currently carried out manually, using the McPhail trap, and the mass spraying is decided based on a decision protocol. We introduce the term 'insect biometrics' in the context of entomology as a measure of a characteristic of the insect (in our case, the spectrum of its wingbeat) that allows us to identify its species and make devices to help face old enemies with modern means. We modify a McPhail type trap into becoming electronic by installing an array of photoreceptors coupled to an infrared emitter, guarding the entrance of the trap. The beating wings of insects flying in the trap intercept the light and the light fluctuation is turned to a recording. Custom-made electronics are developed that are placed as an external add-on kit, without altering the internal space of the trap. Counts from the trap are transmitted using a mobile communication network. This trap introduces a new automated remote-monitoring method different to audio and vision-based systems. We evaluate our trap in large number of insects in the laboratory by enclosing the electronic trap in insectary cages. Our experiments assess the potential of delivering reliable data that can be used to initialize reliably the spraying process at large scales but to also monitor the impact of the spraying process as it eliminates the time-lag between acquiring and delivering insect counts to a central agency. PMID:26544845

  13. Insect Biometrics: Optoacoustic Signal Processing and Its Applications to Remote Monitoring of McPhail Type Traps

    PubMed Central

    Potamitis, Ilyas; Rigakis, Iraklis; Fysarakis, Konstantinos

    2015-01-01

    Monitoring traps are important components of integrated pest management applied against important fruit fly pests, including Bactrocera oleae (Gmelin) and Ceratitis capitata (Widemann), Diptera of the Tephritidae family, which effect a crop-loss/per year calculated in billions of euros worldwide. Pests can be controlled with ground pesticide sprays, the efficiency of which depends on knowing the time, location and extent of infestations as early as possible. Trap inspection is currently carried out manually, using the McPhail trap, and the mass spraying is decided based on a decision protocol. We introduce the term ‘insect biometrics’ in the context of entomology as a measure of a characteristic of the insect (in our case, the spectrum of its wingbeat) that allows us to identify its species and make devices to help face old enemies with modern means. We modify a McPhail type trap into becoming electronic by installing an array of photoreceptors coupled to an infrared emitter, guarding the entrance of the trap. The beating wings of insects flying in the trap intercept the light and the light fluctuation is turned to a recording. Custom-made electronics are developed that are placed as an external add-on kit, without altering the internal space of the trap. Counts from the trap are transmitted using a mobile communication network. This trap introduces a new automated remote-monitoring method different to audio and vision-based systems. We evaluate our trap in large number of insects in the laboratory by enclosing the electronic trap in insectary cages. Our experiments assess the potential of delivering reliable data that can be used to initialize reliably the spraying process at large scales but to also monitor the impact of the spraying process as it eliminates the time-lag between acquiring and delivering insect counts to a central agency. PMID:26544845

  14. Controlled Thermo-Mechanical Processing

    SciTech Connect

    2005-09-01

    The CTMP technology has the potential for widespread application in all major sectors of the domestic tube and pipe industry; two of the largest sectors are seamless mechanical tubing and seamless oil country tubular goods. It has been proven for the spheroidized annealing heat cycle for through-hardened steels and has led to the development of a recipe for automotive gear steels. Potential applications also exist in the smaller sectors of seamless line pipe, pressure tubing, and stainless tubing. The technology could also apply to non-ferrous metal industries, such as titanium.

  15. In vitro resistance mechanisms of Neisseria meningitidis against neutrophil extracellular traps.

    PubMed

    Lappann, Martin; Danhof, Sophia; Guenther, Frank; Olivares-Florez, Silvana; Mordhorst, Ines Louise; Vogel, Ulrich

    2013-08-01

    Neisseria meningitidis (Nm) is a leading cause of septicemia in childhood. Nm septicemia is unique with respect to very quick disease progression, high in vivo bacterial replication rate and its considerable mortality. Nm circumvents major mechanisms of innate immunity such as complement system and phagocytosis. Neutrophil extracellular traps (NETs) are formed from neutrophils during systemic infection and are suggested to contain invading microorganisms. Here, we investigated the interaction of Nm with NETs. Both, meningococci and spontaneously released outer membrane vesicles (SOMVs) were potent NET inducers. NETs were unable to kill NET bound meningococci, but slowed down their proliferation rate. Using Nm as model organism we identified three novel mechanisms how bacteria can evade NET-mediated killing: (i) modification of lipid A of meningococcal LPS with phosphoethanolamine protected Nm from NET-bound cathepsin G; (ii) expression of the high-affinity zinc uptake receptor ZnuD allowed Nm to escape NET-mediated nutritional immunity; (iii) binding of SOMVs to NETs saved Nm from NET binding and the consequent bacteriostatic effect. Escape from NETs may contribute to the most rapid progression of meningococcal disease. The induction of NET formation by Nm in vivo might aggravate thrombosis in vessels ultimately directing to disseminated intravascular coagulation (DIC). PMID:23750848

  16. Different mechanics of snap-trapping in the two closely related carnivorous plants Dionaea muscipula and Aldrovanda vesiculosa.

    PubMed

    Poppinga, Simon; Joyeux, Marc

    2011-10-01

    The carnivorous aquatic waterwheel plant (Aldrovanda vesiculosa L.) and the closely related terrestrial venus flytrap (Dionaea muscipula Sol. ex J. Ellis) both feature elaborate snap-traps, which shut after reception of an external mechanical stimulus by prey animals. Traditionally, Aldrovanda is considered as a miniature, aquatic Dionaea, an assumption which was already established by Charles Darwin. However, videos of snapping traps from both species suggest completely different closure mechanisms. Indeed, the well-described snapping mechanism in Dionaea comprises abrupt curvature inversion of the two trap lobes, while the closing movement in Aldrovanda involves deformation of the trap midrib but not of the lobes, which do not change curvature. In this paper, we present detailed mechanical models for these plants, which are based on the theory of thin solid membranes and explain this difference by showing that the fast snapping of Aldrovanda is due to kinematic amplification of the bending deformation of the midrib, while that of Dionaea unambiguously relies on the buckling instability that affects the two lobes. PMID:22181196

  17. Different mechanics of snap-trapping in the two closely related carnivorous plants Dionaea muscipula and Aldrovanda vesiculosa

    NASA Astrophysics Data System (ADS)

    Poppinga, Simon; Joyeux, Marc

    2011-10-01

    The carnivorous aquatic waterwheel plant (Aldrovanda vesiculosa L.) and the closely related terrestrial venus flytrap (Dionaea muscipula Sol. ex J. Ellis) both feature elaborate snap-traps, which shut after reception of an external mechanical stimulus by prey animals. Traditionally, Aldrovanda is considered as a miniature, aquatic Dionaea, an assumption which was already established by Charles Darwin. However, videos of snapping traps from both species suggest completely different closure mechanisms. Indeed, the well-described snapping mechanism in Dionaea comprises abrupt curvature inversion of the two trap lobes, while the closing movement in Aldrovanda involves deformation of the trap midrib but not of the lobes, which do not change curvature. In this paper, we present detailed mechanical models for these plants, which are based on the theory of thin solid membranes and explain this difference by showing that the fast snapping of Aldrovanda is due to kinematic amplification of the bending deformation of the midrib, while that of Dionaea unambiguously relies on the buckling instability that affects the two lobes.

  18. Irreversible processes from reversible mechanics

    SciTech Connect

    Hoover, W.G.; Hoover, C.G.; Evans, W.J.; Moran, B.; Levatin, J.A.; Craig, E.A.; National Magnetic Fusion Energy Computer Center, Livermore, CA; Lawrence Livermore National Lab., CA; California Univ., Davis, CA . Dept. of Applied Science)

    1989-08-01

    We describe and illustrate methods for treating many-body irreversible processes using time-reversible deterministic Nose-Hoover thermostats. In phase space, Lyapunov-unstable multifractal strange attractors are the common feature representing any of these nonequilibrium flows, be they steady, periodic, or transient. This generic behavior is illustrated here for three prototypical one-body problems: steady field-driven diffusive flow in a Galton Board, time-periodic boundary-driven viscous flow of a Lorentz gas, and transient, but time-periodic, compressible flow characterizing a one-dimensional free expansion followed by compression and thermalization. 20 refs., 25 figs.

  19. Collision Processes of Highly Charged Ions with Electrons Studied with an Electron Beam Ion Trap

    SciTech Connect

    Nakamura, Nobuyuki; Watanabe, Tsutomu; Ohtani, Shunsuke; Kavanagh, Anthony P.; Currell, Fred J.; Watanabe, Hirofumi; Sakaue, Hiroyuki A.; Kato, Daiji; Li Yueming; Tong Xiaoming

    2009-09-10

    The electron beam ion trap in Tokyo (Tokyo-EBIT)is suitable for studying relativistic effects in the collisions of highly charged heavy ions with electrons because it can produce and trap very highly charged heavy ions which interact with a mono-energetic and unidirectional relativistic electron beam with an energy of up to 200 keV. Recently, we have been studying resonant processes in ionization and recombination by measuring the charge abundance inside the EBIT at the equilibrium. The abundance ratio between adjacent charge states varies slowly with the electron energy when there is no resonant process. However, when the electron energy coincides with the resonant energy at which ionization or recombination is enhanced, the abundance ratio can drastically change. Thus, the resonant processes can be studied by measuring the abundance ratio between adjacent ions as a function of electron beam energy. In this talk, recent progress for heavy ions with very high charge states up to He-like Bi{sup 81+}, is presented. For such ions, relativistic effects significantly affect the resonant processes. For example, the generalized Breit interaction (GBI) effect, which treats the retardation in the exchange of single virtual photon between the free and orbital electrons, has been clearly observed in the DR resonant strength in Li-like Bi{sup 80+}. Recently we have also found that the GBI effect plays an important role in the interference between non-resonant and resonant recombinations. Experimental results are presented in comparison with theoretical calculations.

  20. Threat processing: models and mechanisms.

    PubMed

    Bentz, Dorothe; Schiller, Daniela

    2015-01-01

    The experience of fear is closely linked to the survival of species. Fear can be conceptualized as a brain state that orchestrates defense reactions to threats. To avoid harm, an organism must be equipped with neural circuits that allow learning, detecting, and rapidly responding to threats. Past experience with threat can transform neutral stimuli present at the time of experience into learned threat-related stimuli via associative learning. Pavlovian threat conditioning is the central experimental paradigm to study associative learning. Once learned, these stimulus-response associations are not always expressed depending on context or new experiences with the conditioned stimuli. Neural circuits mediating threat learning have the inherent plasticity to adapt to changing environmental threats. Encounters devoid of danger pave the way for extinction or reconsolidation to occur. Extinction and reconsolidation can both lead to changes in the expression of threat-induced defense responses, but differ in stability and have a different neural basis. This review presents the behavioral models and the system-level neural mechanisms in animals and humans of threat learning and modulation. PMID:26267313

  1. Remote trap passivation in colloidal quantum dot bulk nano-heterojunctions and its effect in solution-processed solar cells.

    PubMed

    Rath, Arup K; Pelayo Garcia de Arquer, F; Stavrinadis, Alexandros; Lasanta, Tania; Bernechea, Maria; Diedenhofen, Silke L; Konstantatos, Gerasimos

    2014-07-16

    More-efficient charge collection and suppressed trap recombination in colloidal quantum dot (CQD) solar cells is achieved by means of a bulk nano-heterojunction (BNH) structure, in which p-type and n-type materials are blended on the nanometer scale. The improved performance of the BNH devices, compared with that of bilayer devices, is displayed in higher photocurrents and higher open-circuit voltages (resulting from a trap passivation mechanism). PMID:24895324

  2. Stochastic processes of particle trapping and detrapping by a wave in a magnetized plasma

    SciTech Connect

    Zaslavsky, A.; Krafft, C.; Volokitin, A.

    2006-01-15

    This paper presents some relevant numerical simulations of the three-dimensional evolution of a monochromatic lower hybrid wave interacting at the Landau resonance with a Maxwellian electron beam in a magnetized plasma. A statistical study of the stochastic trapping-detrapping transitions performed by a large set of quasiresonant test particles moving self-consistently in the wave's potential has been carried out using dynamical criteria based on simple physical arguments. The paper allows us to explain the role of the stochastic processes at work in the wave-particle interactions and to shed light on their influence on the dynamical evolution of the system over a long range of time.

  3. Monitoring stored-product pests in food processing plants with pheromone trapping, contour mapping, and mark-recapture.

    PubMed

    Campbell, J F; Mullen, M A; Dowdy, A K

    2002-10-01

    Distribution and movement patterns of several species of stored-product pests in a food processing plant were investigated. The objectives of this study were to determine the temporal and spatial variation in abundance of stored-product pests using pheromone traps; assess the effectiveness of trap type, location, and number on monitoring insect populations; and to evaluate the nature of pheromone trap capture hot spots by measuring patterns of insect movement. We determined that the distributions of Trogoderma variabile Ballion, Lasioderina serricorne (F.), Tribolium castaneum (Herbst), and Plodia interpunctella (Hbner) within the facility were typically clumped and that foci of high trap captures, based on visual observation of contour maps, varied among species and over time. Trap type and location influenced the number of T. variabile captured: traps on the floor and along walls captured more individuals than hanging traps and traps next to support pillars. T. variabile was the predominant insect pest at this facility and from mark-recapture studies, we found that individual beetles moved across multiple floors in the facility and from 7 to 216 m though the warehouse. PMID:12403439

  4. 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.

  5. Deflection of a ?-type three-level atom by a light field: a mechanical demonstration of the coherent population trapping effect

    NASA Astrophysics Data System (ADS)

    Aldossary, Omar M.; Lembessis, Vassilis E.

    2012-06-01

    We consider the deflection of a three-level atom of ?-type interacting with a light field of two coherent laser beams. We employ the dressed state formalism, which is suitable for large Rabi frequencies and/or large detunings. A full study of the interaction and relaxation processes is performed. We show that a beam of atoms is split into three beams once it crosses the light field. This is a three-state version of the well-known optical Stern-Gerlach effect, which has been theoretically studied and experimentally demonstrated for two-level atoms. Under coherent population trapping conditions, the splitting of the beam becomes twofold. This gives us, in principle, the opportunity of a mechanical demonstration of the coherent population trapping effect.

  6. 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.

  7. Mass measurements along the rp-process path using the Canadian Penning trap mass spectrometer

    NASA Astrophysics Data System (ADS)

    Clark, J. A.; Vaz, J.; Wang, J. C.; Boudreau, C.; Barber, R. C.; Sharma, K. S.; Blank, B.; Heinz, A.; Levand, A. F.; Savard, G.; Seweryniak, D.; Trimble, W.; Zhou, Z.; Buchinger, F.; Crawford, J. E.; Gulick, S.; Lee, J. K. P.; Sprouse, G. D.

    2003-10-01

    The processes responsible for the creation of elements more massive than iron are not well understood. A possible scenario for their production involves the rapid capture of protons (rp-process), which is thought to occur in explosive astrophysical events such as novae and X-ray bursts. Mass measurements of the nuclides involved with uncertainties on the order of 100 keV or better are critical to determine the energy output of the events, the resulting nuclide abundances, and the process 'path' including its termination. Particularly important are the masses of 'waiting-point' nuclides along the rp-process path where the process stalls until the subsequent ?-decay of the nuclides. This contribution will discuss the precise (< 30 keV) mass measurements made of isotopes along the rp-process path using the Canadian Penning Trap mass spectrometer (located at the ATLAS facility of the Argonne National Laboratory). Most notably, our results include the masses of two critical waiting-point nuclides, ^64Ge and ^68Se, and masses of isotopes near the proposed end-point of the rp-process path. This work was supported by grants from the Natural Sciences and Engineering Research Council of Canada and by the U.S. Department of Energy, Nuclear Physics Division, under Contract W-31-109-ENG-38.

  8. Characterisation of FOGs in grease trap waste from the processing of chickens in Thailand.

    PubMed

    Nitayapat, Nuttakan; Chitprasert, Pakamon

    2014-06-01

    Industrial firms that kill and process chickens generate wastewater that contains fat, oil, and grease (FOG). The FOGs are located in the fatty waste that is collected by floatation in grease traps. Chemical and physical characterisation of FOGs would provide useful information that would help in the development of methods designed to decrease the extent of pollution caused by disposal of the waste and to utilise commercially some of its lipid constituents. Employing these methods would enhance the profitability and competitive potential of these commercial organisations. Samples of grease trap waste from 14 firms in central Thailand have been examined. Due to the very different schemes of waste management employed by these firms, the physical appearance of their fatty wastes showed considerable variation. The chemical and physical properties of the FOGs present in these wastes showed considerable variation also. Large amounts of free fatty acids (10-70% as oleic acid) were detected in most of the 14 wastes and palmitic, cis-9-oleic, cis,cis-9,12-linoleic, stearic, and palmitoleic acids were the predominant species of free and esterified acids. Most of the FOGs were solid at temperatures below 40 C. Many of them contained traces of heavy metals (Cu and Pb) and some contained traces of the pesticides dimethoate and cypermethrin. The content of these potentially hazardous substances would have to be considered very carefully before discarding the fatty wastes and during the development of methods designed to isolate their potentially profitable lipid constituents. PMID:24095036

  9. 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/Vs and the corresponding electron mobility-lifetime product is found to be 1.3210-3 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).

  10. 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.

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

    SciTech Connect

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

    2011-05-15

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

  12. 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.

  13. Sensory trap as the mechanism of sexual selection in a damselfly genitalic trait (Insecta: Calopterygidae).

    PubMed

    Crdoba-Aguilar, A

    2002-11-01

    During copulation, males of some calopterygid damselfly species displace the sperm stored in the spermatheca: the male genital appendages enter into the spermathecal ducts and physically remove sperm. In Calopteryx haemorrhoidalis, the genital appendages are too wide to penetrate the spermathecae, but males use a different mechanism in which the aedeagus stimulates the vaginal sensilla that control spermathecal sperm release. Since these sensilla are used during egg fertilization and oviposition, it was hypothesized that this function evolved before the male stimulatory ability. I investigated this using Hetaerina cruentata, a species whose position in the Calopterygidae phylogeny is more basal than Calopteryx. Given this position and having determined that males of this species are not able to displace sperm of their conspecific females during copulation, it was expected that H. cruentata females would eject sperm when stimulated with the aedeagi of C. haemorrhoidalis but not when stimulated with the aedeagi of their conspecifics. This prediction was confirmed. In order to investigate the widespread nature of this result, some other Calopteryx species-Calopteryx xanthostoma and Calopteryx virgo-were investigated. The results were similar to those of H. cruentata: conspecific males were unable to stimulate their females, but females ejected sperm when stimulated with C. haemorrhoidalis aedeagi. Morphometric analysis suggests that the mechanistic explanation for the stimulatory ability of C. haemorrhoidalis genitalia is that the aedeagal region that makes contact with the vaginal sensilla is wider in C. haemorrhoidalis than in the other species. These results suggest that the sensory "bias" shown and shared by H. cruentata, Calopteryx splendens, C. virgo, and C. haemorrhoidalis females represents an ancestral condition and that the male stimulatory ability is absent in the evolutionary history of the clade. These pieces of evidence as well as another one presented elsewhere, which indicates that C. haemorrhoidalis males vary in their stimulatory ability, constitute the three criteria for a case of sexual selection via exploitation of a female sensory bias. These results also provide support to the sensory trap hypothesis that indicates that the female bias-in this case, egg fertilization and oviposition-evolved in a context different from sexual selection. Considering that the male genital appendages responsible for physically removing spermathecal sperm in other calopterygids are present in C. haemorrhoidalis, I suggest that males were once able to displace spermathecal sperm physically. Such ability may have been later impeded by a reduction in size of the spermathecal ducts. Possibly, one of the latest events in this sequence is the male's stimulatory ability. This hypothetical series of events suggests a coevolutionary scenario in which the central actor is the sperm stored in the spermathecae. PMID:18707510

  14. Graphene quantum dots as a highly efficient solution-processed charge trapping medium for organic nano-floating gate memory.

    PubMed

    Ji, Yongsung; Kim, Juhan; Cha, An-Na; Lee, Sang-A; Lee, Myung Woo; Suh, Jung Sang; Bae, Sukang; Moon, Byung Joon; Lee, Sang Hyun; Lee, Dong Su; Wang, Gunuk; Kim, Tae-Wook

    2016-04-01

    A highly efficient solution-processible charge trapping medium is a prerequisite to developing high-performance organic nano-floating gate memory (NFGM) devices. Although several candidates for the charge trapping layer have been proposed for organic memory, a method for significantly increasing the density of stored charges in nanoscale layers remains a considerable challenge. Here, solution-processible graphene quantum dots (GQDs) were prepared by a modified thermal plasma jet method; the GQDs were mostly composed of carbon without any serious oxidation, which was confirmed by x-ray photoelectron spectroscopy. These GQDs have multiple energy levels because of their size distribution, and they can be effectively utilized as charge trapping media for organic NFGM applications. The NFGM device exhibited excellent reversible switching characteristics, with an on/off current ratio greater than 10(6), a stable retention time of 10(4) s and reliable cycling endurance over 100 cycles. In particular, we estimated that the GQDs layer trapped ∼7.2 × 10(12) cm(-2) charges per unit area, which is a much higher density than those of other solution-processible nanomaterials, suggesting that the GQDs layer holds promise as a highly efficient nanoscale charge trapping material. PMID:26905768

  15. 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.

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

    SciTech Connect

    Booth, Ivan; Fairhurst, Stephen

    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.

  17. Influence of interlayer trapping and detrapping mechanisms on the electrical characterization of hafnium oxide/silicon nitride stacks on silicon

    SciTech Connect

    Garcia, H.; Duenas, S.; Castan, H.; Gomez, A.; Bailon, L.; Toledano-Luque, M.; Prado, A. del; Martil, I.; Gonzalez-Diaz, G.

    2008-11-01

    Al/HfO{sub 2}/SiN{sub x}:H/n-Si metal-insulator-semiconductor capacitors have been studied by electrical characterization. Films of silicon nitride were directly grown on n-type silicon substrates by electron cyclotron resonance assisted chemical vapor deposition. Silicon nitride thickness was varied from 3 to 6.6 nm. Afterwards, 12 nm thick hafnium oxide films were deposited by the high-pressure sputtering approach. Interface quality was determined by using current-voltage, capacitance-voltage, deep-level transient spectroscopy (DLTS), conductance transients, and flatband voltage transient techniques. Leakage currents followed the Poole-Frenkel emission model in all cases. According to the simultaneous measurement of the high and low frequency capacitance voltage curves, the interface trap density obtained for all the samples is in the 10{sup 11} cm{sup -2} eV{sup -1} range. However, a significant increase in this density of about two orders of magnitude was obtained by DLTS for the thinnest silicon nitride interfacial layers. In this work we probe that this increase is an artifact that must be attributed to traps existing at the HfO{sub 2}/SiN{sub x}:H intralayer interface. These traps are more easily charged or discharged as this interface comes near to the substrate, that is, as thinner the SiN{sub x}:H interface layer is. The trapping/detrapping mechanism increases the capacitance transient and, in consequence, the DLTS measurements have contributions not only from the insulator/substrate interface but also from the HfO{sub 2}/SiN{sub x}:H intralayer interface.

  18. Fluid mechanics mechanisms in the stall process of helicopters

    NASA Technical Reports Server (NTRS)

    Young, W. H., Jr.

    1981-01-01

    Recent experimental results from airfoils in the Mach number, Reynolds number, or reduced frequency ranges typical of helicopter rotor blades have identified the most influential flow mechanisms in the dynamic stall process. The importance of secondary shed vortices, downstream wake action, and the flow in the separated region is generally acknowledged but poorly understood. By means of surface pressure cross-correlations and flow field measurements in static stall, several new hypotheses have been generated. It is proposed that vortex shedding may be caused by acoustic disturbances propagating forward in the lower (pressure) surface boundary layer, that wake closure is a misnomer, and that the shed vortex leaves a trail of vorticity that forms a turbulent free shear layer. The known dynamic stall flow mechanisms are reviewed and the potential importance of recently proposed and hypothetical flow phenomena with respect to helicopter blade aeroelastic response are assessed.

  19. 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.

  20. Quantum information processing and quantum-limited metrology using trapped ions at NIST.

    NASA Astrophysics Data System (ADS)

    Wineland, David

    2007-03-01

    With the use of atomic ions confined in a multi-zone array, we implement simple quantum algorithms and study the problems in scaling such a device to tens of qubits [1]. Current work is devoted to better control of classical parameters such as laser intensity, suppression of heating from ambient fluctuating electric fields, and studying limitations caused by more fundamental sources of decoherence, such as spontaneous emission. Along with other groups, we are studying ways to increase the number of trap zones; in particular, we concentrate on a surface-electrode multi-zone geometry. Although a general purpose quantum computer appears to be a distant goal, simple applications of quantum information processing methods enable new techniques for spectroscopy and efficient quantum detection. [1] Current research in collaboration with D. Leibfried, J. Amini, J. C. Bergquist, R. B. Blakestad, J. J. Bollinger, J. Britton, K. Brown, R. J. Epstein, D. B. Hume, W. M. Itano, J. D. Jost, E. Knill, C. Langer, R. Ozeri, T. Rosenband, S. Seidelin, N. Shiga, and J. H. Wesenberg.

  1. Spectroscopic studies of the charge breeding process in high current electron beam ion traps

    NASA Astrophysics Data System (ADS)

    Baumann, T. M.; Crespo López-Urrutia, J. R.; Schwarz, S.; Lapierre, A.; Bollen, G.; Kester, O.; Dilling, J.; Ullrich, J.

    2012-11-01

    Electron beam ion traps (EBITs) are a new tool for charge breeding of rare isotope beams. The ionization efficiency of a new high current EBIT recently built at the MPIK was investigated spectroscopically during its commissioning phase.

  2. Mechanism on brain information processing: Energy coding

    NASA Astrophysics Data System (ADS)

    Wang, Rubin; Zhang, Zhikang; Jiao, Xianfa

    2006-09-01

    According to the experimental result of signal transmission and neuronal energetic demands being tightly coupled to information coding in the cerebral cortex, the authors present a brand new scientific theory that offers a unique mechanism for brain information processing. They demonstrate that the neural coding produced by the activity of the brain is well described by the theory of energy coding. Due to the energy coding model's ability to reveal mechanisms of brain information processing based upon known biophysical properties, they cannot only reproduce various experimental results of neuroelectrophysiology but also quantitatively explain the recent experimental results from neuroscientists at Yale University by means of the principle of energy coding. Due to the theory of energy coding to bridge the gap between functional connections within a biological neural network and energetic consumption, they estimate that the theory has very important consequences for quantitative research of cognitive function.

  3. Trapped antihydrogen

    NASA Astrophysics Data System (ADS)

    Butler, E.; Andresen, G. B.; Ashkezari, M. D.; Baquero-Ruiz, M.; Bertsche, W.; Bowe, P. D.; 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.; Jrgensen, L. V.; Kemp, S. L.; Kurchaninov, L.; Madsen, N.; Menary, S.; Nolan, P.; Olchanski, K.; Olin, A.; Povilus, A.; Pusa, P.; Rasmussen, C. .; Robicheaux, F.; Sarid, E.; Seif el Nasr, S.; Silveira, D. M.; So, C.; Storey, J. W.; Thompson, R. I.; van der Werf, D. P.; Wurtele, J. S.; Yamazaki, Y.

    2012-12-01

    Precision spectroscopic comparison of hydrogen and antihydrogen holds the promise of a sensitive test of the Charge-Parity-Time theorem and matter-antimatter equivalence. The clearest path towards realising this goal is to hold a sample of antihydrogen in an atomic trap for interrogation by electromagnetic radiation. Achieving this poses a huge experimental challenge, as state-of-the-art magnetic-minimum atom traps have well depths of only 1 T (0.5 K for ground state antihydrogen atoms). The atoms annihilate on contact with matter and must be `born' inside the magnetic trap with low kinetic energies. At the ALPHA experiment, antihydrogen atoms are produced from antiprotons and positrons stored in the form of non-neutral plasmas, where the typical electrostatic potential energy per particle is on the order of electronvolts, more than 104 times the maximum trappable kinetic energy. In November 2010, ALPHA published the observation of 38 antiproton annihilations due to antihydrogen atoms that had been trapped for at least 172 ms and then releasedthe first instance of a purely antimatter atomic system confined for any length of time (Andresen et al., Nature 468:673, 2010). We present a description of the main components of the ALPHA traps and detectors that were key to realising this result. We discuss how the antihydrogen atoms were identified and how they were discriminated from the background processes. Since the results published in Andresen et al. (Nature 468:673, 2010), refinements in the antihydrogen production technique have allowed many more antihydrogen atoms to be trapped, and held for much longer times. We have identified antihydrogen atoms that have been trapped for at least 1,000 s in the apparatus (Andresen et al., Nature Physics 7:558, 2011). This is more than sufficient time to interrogate the atoms spectroscopically, as well as to ensure that they have relaxed to their ground state.

  4. Trapped antihydrogen

    NASA Astrophysics Data System (ADS)

    Butler, E.; Andresen, G. B.; Ashkezari, M. D.; Baquero-Ruiz, M.; Bertsche, W.; Bowe, P. D.; 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.; Jrgensen, L. V.; Kemp, S. L.; Kurchaninov, L.; Madsen, N.; Menary, S.; Nolan, P.; Olchanski, K.; Olin, A.; Povilus, A.; Pusa, P.; Rasmussen, C. .; Robicheaux, F.; Sarid, E.; Seif el Nasr, S.; Silveira, D. M.; So, C.; Storey, J. W.; Thompson, R. I.; van der Werf, D. P.; Wurtele, J. S.; Yamazaki, Y.

    Precision spectroscopic comparison of hydrogen and antihydrogen holds the promise of a sensitive test of the Charge-Parity-Time theorem and matter-antimatter equivalence. The clearest path towards realising this goal is to hold a sample of antihydrogen in an atomic trap for interrogation by electromagnetic radiation. Achieving this poses a huge experimental challenge, as state-of-the-art magnetic-minimum atom traps have well depths of only 1 T (0.5 K for ground state antihydrogen atoms). The atoms annihilate on contact with matter and must be `born' inside the magnetic trap with low kinetic energies. At the ALPHA experiment, antihydrogen atoms are produced from antiprotons and positrons stored in the form of non-neutral plasmas, where the typical electrostatic potential energy per particle is on the order of electronvolts, more than 104 times the maximum trappable kinetic energy. In November 2010, ALPHA published the observation of 38 antiproton annihilations due to antihydrogen atoms that had been trapped for at least 172 ms and then releasedthe first instance of a purely antimatter atomic system confined for any length of time (Andresen et al., Nature 468:673, 2010). We present a description of the main components of the ALPHA traps and detectors that were key to realising this result. We discuss how the antihydrogen atoms were identified and how they were discriminated from the background processes. Since the results published in Andresen et al. (Nature 468:673, 2010), refinements in the antihydrogen production technique have allowed many more antihydrogen atoms to be trapped, and held for much longer times. We have identified antihydrogen atoms that have been trapped for at least 1,000 s in the apparatus (Andresen et al., Nature Physics 7:558, 2011). This is more than sufficient time to interrogate the atoms spectroscopically, as well as to ensure that they have relaxed to their ground state.

  5. 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.

  6. Light-bias coupling erase process for non-volatile zinc tin oxide TFT memory with a nickel nanocrystals charge trap layer

    NASA Astrophysics Data System (ADS)

    Li, Jeng-Ting; Liu, Li-Chih; Ke, Po-Hsien; Chen, Jen-Sue; Jeng, Jiann-Shing

    2016-03-01

    A nonvolatile charge trapping memory is demonstrated on a thin film transistor (TFT) using a solution processed ultra-thin (~7 nm) zinc tin oxide (ZTO) semiconductor layer with an Al2O3/Ni-nanocrystals (NCs)/SiO2 dielectric stack. A positive threshold voltage (V TH) shift of 7 V is achieved at gate programming voltage of 40 V for 1 s but the state will not be erased by applying negative gate voltage. However, the programmed V TH shift can be expediently erased by applying a gate voltage of  ‑10 V in conjunction with visible light illumination for 1 s. It is found that the sub-threshold swing (SS) deteriorates slightly under light illumination, indicating that photo-ionized oxygen vacancies (V\\text{o}+ and/or V\\text{o}++ ) are trapped at the interface between Al2O3 and ZTO, which assists the capture of electrons discharged from the Ni NCs charge trapping layer. The light-bias coupling action and the role of ultra-thin ZTO thickness are discussed to elucidate the efficient erasing mechanism.

  7. Uncovering the Mechanism of Trapping and Cell Orientation during Neisseria gonorrhoeae Twitching Motility

    PubMed Central

    Zaburdaev, Vasily; Biais, Nicolas; Schmiedeberg, Michael; Eriksson, Jens; Jonsson, Ann-Beth; Sheetz, MichaelP.; Weitz, DavidA.

    2014-01-01

    Neisseria gonorrheae bacteria are the causative agent of the second most common sexually transmitted infection in the world. The bacteria move on a surface by means of twitching motility. Their movement is mediated by multiple long and flexible filaments, called type IV pili, that extend from the cell body, attach to the surface, and retract, thus generating a pulling force. Moving cells also use pili to aggregate and form microcolonies. However, the mechanism by which the pili surrounding the cell body work together to propel bacteria remains unclear. Understanding this process will help describe the motility of N.gonorrheae bacteria, and thus the dissemination of the disease which they cause. In this article we track individual twitching cells and observe that their trajectories consist of alternating moving and pausing intervals, while the cell body is preferably oriented with its wide side toward the direction of motion. Based on these data, we propose a model for the collective pili operation of N.gonorrheae bacteria that explains the experimentally observed behavior. Individual pili function independently but can lead to coordinated motion or pausing via the force balance. The geometry of the cell defines its orientation during motion. We show that by changing pili substrate interactions, the motility pattern can be altered in a predictable way. Although the model proposed is tangibly simple, it still has sufficient robustness to incorporate further advanced pili features and various cell geometries to describe other bacteria that employ pili to move on surfaces. PMID:25296304

  8. Electron bunching in a Penning trap and accelerating process for CO2 gas mixture active medium

    NASA Astrophysics Data System (ADS)

    Tian, Xiu-Fang; Wu, Cong-Feng; Jia, Qi-Ka

    2015-12-01

    In PASER (particle acceleration by stimulated emission of radiation), in the presence of an active medium incorporated in a Penning trap, moving electrons can become bunched, and as they get enough energy, they escape the trap forming an optical injector. These bunched electrons can enter the next PASER section filled with the same active medium to be accelerated. In this paper, electron dynamics in the presence of a gas mixture active medium incorporated in a Penning trap is analyzed by developing an idealized 1D model. We evaluate the energy exchange occurring as the train of electrons traverses into the next PASER section. The results show that the oscillating electrons can be bunched at the resonant frequency of the active medium. The influence of the trapped time and population inversion are analyzed, showing that the longer the electrons are trapped, the more energy from the medium the accelerated electrons get, and with the increase of population inversion, the decelerated electrons are virtually unchanged but the accelerated electrons more than double their peak energy values. The simulation results show that the gas active medium needs a lower population inversion to bunch the electrons compared to a solid active medium, so the experimental conditions can easily be achieved. Supported by National Natural Science Foundation of China (10675116) and Major State Basic Research Development Programme of China (2011CB808301)

  9. A computational model of hemorrhage and dehydration suggests a pathophysiological mechanism: Starling-mediated protein trapping.

    PubMed

    Reisner, Andrew T; Heldt, Thomas

    2013-02-15

    We sought to understand the degree to which a single computational cardiovascular model could replicate the typical responses of healthy subjects through a breadth of blood loss patterns and whether such a model could illuminate the cause-effect relationships that underlie the observed responses. The model consisted of compartments for the upper body, lower body, viscera, and kidneys as well as a four-chambered heart and a pulmonary compartment. Transcapillary fluid flux was governed by Starling forces, whereas lymphatic flow was driven by hydrostatic tissue pressure and scaled by a lymphatic activation term. We adjusted parameters based on results from one protocol involving moderate continual blood loss in a canine model. Next, we simulated six additional protocols spanning euvolemic and dehydrated subjects and compared in silico behavior with in vivo hemodynamic responses and fluid shifts. The model was able to replicate group-averaged behavior (i.e., within 1 or 2 SEs) of the rate and quantity of vascular refill and the associated cardiac output during slow, moderate, and rapid ongoing blood losses, the restitution after the cessation of blood loss, and the absence of restitution in dehydrated subjects. The model suggested that the earlier phase of restitution, i.e., transcapillary fluid shifts, was antagonistic to the later phase of restitution, i.e., protein return via lymphatics. This phenomenon was termed "interstitial protein trapping." In conclusion, the model appears valid for a range of blood loss patterns and prehydration states. Further investigation into the in vivo relevance of interstitial protein trapping is justified. PMID:23203962

  10. Underlying mechanisms for commuting and migration processes

    NASA Astrophysics Data System (ADS)

    Simini, Filippo; Barabasi, Albert-Laszlo; Bagrow, James

    2012-02-01

    Both frequent commuting and long-term migration are complex human processes that strongly depend on socio-demographic, spatial, political, and even economic factors. We can describe both processes using weighted networks, in which nodes represent geographic locations and link weights denote the flux of individuals who commute (or migrate) between locations. Although both processes concern the movements of individuals, they are very different: commuting takes place on a daily (or weekly) basis and always between the same two locations, while migration is a rare, one-way displacement. Despite these differences, a recently proposed stochastic model, the Radiation model, provides evidence that both processes may be successfully described by the same underlying mechanism. For example, quantities of interest for either process, such as the distributions of trip length and destination populations, appear remarkably similar to the model's predictions. We explore the similarities and differences between commuting and migration both empirically, using census data for the United States, and theoretically, by comparing these commuting and migration networks to the predictions given by the Radiation model.

  11. [Mechanized system for planning technological processes].

    PubMed

    Pashchenko, V S; Shapiro, A M

    1977-01-01

    A mechanized system for the production processes planning involving the use of an electronic code device for data preparation on a punched tape of the "EPECT-IT" type, at the base of which there are classifiers of standard operations and transitions to individual design members, is considered. A fragment of the classifier and a skeleton diagram of the system are presented. It is pointed out that the use of the system helps improve the quality of the design work, as well as to yield considerable economic advantages. The system is in operation at some enterprises of the medical engineering industry. PMID:870789

  12. 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.

  13. Mechanical and cellular processes driving cervical myelopathy

    PubMed Central

    Dolan, Roisin T; Butler, Joseph S; O’Byrne, John M; Poynton, Ashley R

    2016-01-01

    Cervical myelopathy is a well-described clinical syndrome that may evolve from a combination of etiological mechanisms. It is traditionally classified by cervical spinal cord and/or nerve root compression which varies in severity and number of levels involved. The vast array of clinical manifestations of cervical myelopathy cannot fully be explained by the simple concept that a narrowed spinal canal causes compression of the cord, local tissue ischemia, injury and neurological impairment. Despite advances in surgical technology and treatment innovations, there are limited neuro-protective treatments for cervical myelopathy, which reflects an incomplete understanding of the pathophysiological processes involved in this disease. The aim of this review is to provide a comprehensive overview of the key pathophysiological processes at play in the development of cervical myelopathy. PMID:26807352

  14. 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 str...

  15. 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...

  16. Charge-trap non-volatile memories fabricated by laser-enabled low-thermal budget processes

    NASA Astrophysics Data System (ADS)

    Huang, Wen-Hsien; Shieh, Jia-Min; Pan, Fu-Ming; Yang, Chih-Chao; Shen, Chang-Hong; Wang, Hsing-Hsiang; Hsieh, Tung-Ying; Wu, Ssu-Yu; Wu, Meng-Chyi

    2015-11-01

    We fabricated charge-trap non-volatile memories (NVMs) using low thermal budget processes, including laser-crystallization of poly-Si thin film, chemical vapor deposition deposition of a stacked memory layer, and far-infrared-laser dopant activation. The thin poly-Si channel has a low defect-density at the interface with the bulk, resulting in a steep subthreshold swing for the NVM transistors. The introduction of the stacked SiO2/AlOxNy tunnel layer and the SiNx charge-trap layer with a gradient bandgap leads to reliable retention and endurance at low voltage for the NVMs. The low thermal budget processes are desirable for the integration of the nano-scaled NVMs into system on panels.

  17. An active process in cochlear mechanics.

    PubMed

    Davis, H

    1983-01-01

    A model for cochlear mechanics is proposed to take account of its two systems, one passive and one active. The classical passive system stimulates the inner hair cells directly at levels above about 40 dB SL. At intensities below about 60 dB an active process, the 'cochlear amplifier' (CA), somehow provides additional energy that enhances the vibration of a narrow segment of the basilar membrane near the apical foot of the familiar, traveling wave envelope. The outer hair cells are essential for CA. The active system acts like a high-Q acoustic resonator, and it accounts for the great sensitivity and sharp tuning expressed by the 'tips' of neural tuning curves. The tips are selectively vulnerable to anoxia, noise exposure and other trauma. The CA model explains the detection of small differences in time as well as in frequency, the dual character of the electrocochleogram, recruitment of loudness in cochlear hearing impairment, the long latency of normal neural responses near threshold, acoustic emissions (both stimulated and spontaneous) and the locus of TTS in the frequency range above the exposure tone. Both the classical high-intensity system and the active low-level CA system are highly nonlinear and they combine to compress the great dynamic range of hearing into a much narrower range of mechanical movement of the cilia of the inner hair cells. The mechanism of CA is unknown, and the problem remains of how its action can be triggered by submolecular movements near threshold. PMID:6826470

  18. Photonic crystal structures for light trapping in thin-film Si solar cells: Modeling, process and optimizations

    NASA Astrophysics Data System (ADS)

    Sheng, Xing; Broderick, Lirong Z.; Kimerling, Lionel C.

    2014-03-01

    In this paper, we present our efforts on studying light trapping in thin-film silicon solar cells using photonic crystal (PC) based structures. Specifically, we propose a photonic backside texture combining periodic gratings and a distributed Bragg reflector (DBR). The mechanisms of this integrated photonic design are theoretically studied and compared with conventional PCs. We experimentally fabricate the texture using lithographic and self-assembled method on thin-film single crystalline Si (c-Si) and micro-crystalline Si (?c-Si) cells. We analyze the effects of the photonic textures on different cells and demonstrate the performance improvements. A numerical method is developed to explore the optimal multiscale textured surface and investigate light trapping limits in the wave optics regime. Using a detailed balance analysis, we show that it is possible to reach over 20% efficiency for 1.5 ?m Si cells through optimal device design and fabrication.

  19. 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; Snchez, 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.

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

    SciTech Connect

    Bodensiek, Kai Li, Weixing; Snchez, Paula; Nawaz, Schanila; Schaap, Iwan A. T.; Center for Nanoscale Microscopy and Molecular Physiology of the Brain , Gttingen

    2013-11-15

    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.

  1. 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

  2. Processing and Mechanical Properties of Baroplastics

    NASA Astrophysics Data System (ADS)

    Gonzalez, Juan; Ryu, Sang-Woog; Acar, Metin; Mayes, Anne

    2004-03-01

    Baroplastics are polymers capable of flow at reduced temperatures with the application of pressure. Block copolymers and core-shell nanoparticles comprised of a low glass transition (Tg) component, such as poly(butyl acrylate) and a high Tg component, such as polystyrene, component have been processed at temperatures as low as 25oC in simple compression molding experiments under pressure of 5000 psi. Baroplastics components present pressure-induced miscibility, resulting in a mixture able to flow at temperatures below the Tg of the glassy component when pressure is applied. Characterization of these materials by DSC, TEM, AFM and SANS shows that the distinct domains of each component remain even after several reprocessing steps. Tensile stress measurements were carried out in different processed and recycled baroplastics showing a wide range of properties are possible upon changing their sizes, composition and structure. It is shown that baroplastics are capable of flow and form when mixed with inorganic components, such as SiO2 nanoparticles, resulting in a nanocomposite with improved mechanical behavior. Simple extrusion experiments, in addition to compression molding processing, were done to demonstrate the flow of baroplastics under pressure and their potential use in commercial extrusion machines.

  3. 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 (~8590%), and the remaining products (1015%) 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

  4. Microbial invasions: the process, patterns, and mechanisms.

    PubMed

    Mallon, Cyrus Alexander; Elsas, Jan Dirk van; Salles, Joana Falcão

    2015-11-01

    There has recently been a surge of literature examining microbial invasions into a variety of environments. These studies often include a component of biological diversity as a major factor determining an invader's fate, yet common results are rarely cross-compared. Since many studies only present a snapshot of the entire invasion process, a bird's eye view is required to piece together the entire continuum, which we find consists of introduction, establishment, spread, and impact phases. We further examine the patterns and mechanisms associated with invasion resistance and create a mechanistic synthesis governed by the species richness, species evenness, and resource availability of resident communities. We conclude by exploring the advantages of using a theoretical invasion framework across different fields. PMID:26439296

  5. Brain mechanisms involved in processing unreal perceptions.

    PubMed

    Ku, Jeonghun; Kim, Jae-Jin; Jung, Young Chul; Park, Il Ho; Lee, Hyeongrae; Han, Kiwan; Yoon, Kang Jun; Kim, In Young; Kim, Sun I

    2008-12-01

    Individuals sometimes experience an illusory or hallucinatory perception. This unreal perception is usually resolved after the individual recognizes that the perception was not real. In this study, we investigated the brain mechanisms involved in the process to an illusory or hallucinatory perception through 'obtaining insight into unreality'. We used a novel and intuitive paradigm designed by combining functional magnetic resonance imaging and augmented reality technology to simulate visual illusory stimuli that mimic hallucinations during brain scanning. The results showed various brain activations, predominantly in the amygdala in the early phase, the medial frontal cortex and the occipitotemporal junction in the middle phase, and the thalamus in the late phase, which correlated with a subject's proneness to hallucinating. These activations may correspond to a 'responding stage' for a perception-based immediate emotional reaction, a 'monitoring stage' for integration and recalibration to ascertain that the perception was not real, and a 'resolving stage' for controlling the information and finally settling it, respectively. Our paradigm and findings may be useful in understanding the mechanisms for discriminating and coping with hallucinatory perceptions. PMID:18801444

  6. Coordination-directed self-assembly of M12L24 nanocage: effects of kinetic trapping on the assembly process.

    PubMed

    Yoneya, Makoto; Tsuzuki, Seiji; Yamaguchi, Tomohiko; Sato, Sota; Fujita, Makoto

    2014-02-25

    We demonstrate the spontaneous formation of spherical complex M12L24, which is composed of 12 palladium ions and 24 bidentate ligands, by molecular dynamics simulations. In contrast to our previous study on the smaller M6L8 cage, we found that the larger M12L24 self-assembly process involves noticeable kinetic trapping at lower nuclearity complexes, e.g., M6L12, M8L16, and M9L18. We also found that the kinetic trapping behaviors sensitively depend on the bend angle of ligands and the metal-ligand binding strength. Our results show that these kinetic effects, that have generally been neglected, are important factor in self-assembly structure determination of larger complexes as M12L24 in this study. PMID:24476127

  7. Planar defects as Ar traps in trioctahedral micas: A mechanism for increased Ar retentivity in phlogopite

    NASA Astrophysics Data System (ADS)

    Camacho, A.; Lee, J. K. W.; Fitz Gerald, J. D.; Zhao, J.; Abdu, Y. A.; Jenkins, D. M.; Hawthorne, F. C.; Kyser, T. K.; Creaser, R. A.; Armstrong, R.; Heaman, L. W.

    2012-08-01

    The effects of planar defects and composition on Ar mobility in trioctahedral micas have been investigated in samples from a small marble outcrop (?500 m2) in the Frontenac Terrane, Grenville Province, Ontario. These micas crystallized during amphibolite-facies metamorphism at ?1170 Ma and experienced a thermal pulse ?100 Ma later at shallow crustal levels associated with the emplacement of plutons. 87Rb/86Sr ages of the phlogopites range from ?950 to ?1050 Ma, consistent with resetting during the later thermal event. The same phlogopites however, give 40Ar/39Ar ages between ?950 and 1160 Ma, spanning the age range of the two thermal events. This result is intriguing because these micas have undergone the same thermal history and were not deformed after peak metamorphic conditions. In order to understand this phenomenon, the chemical, crystallographical, and microstructural nature of four mica samples has been characterized in detail using a wide range of analytical techniques. The scanning electron microscope (SEM), electron microprobe (EMP), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) data show that the micas are chemically homogeneous (with the exception of Ba) and similar in composition. The Fourier transform infrared spectroscopy and Mossbauer results show that the M sites for three of the micas are dominated by divalent cations and the Fe3+/(Fe2++Fe3+) ratio for all four phlogopites ranges from 0.10 to 0.25. The stable-isotopic data for calcite indicate that this outcrop was not affected by hydrothermal fluids after peak metamorphism. No correlation between chemical composition and 87Rb/86Sr and 40Ar/39Ar age or between crystal size and 40Ar/39Ar age is observed. The only major difference among all of the micas was revealed through transmitted electron microscope (TEM), which shows that the older 1M micas contain significantly more layer stacking defects, associated with crystallization, than the younger micas. We propose that these defect structures, which are enclosed entirely within the mineral grain may serve as Ar traps and effectively increase the Ar retentivity of the mineral. As this phenomenon has not been previously documented in micas, this may have significant implications for the interpretation of 40Ar/39Ar ages of minerals which have similar defect structures.

  8. 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

  9. Neural mechanisms of spatiotemporal signal processing

    NASA Astrophysics Data System (ADS)

    Khanbabaie Shoub, Shaban (Reza)

    We have studied the synaptic, dendritic, and network mechanisms of spatiotemporal signal processing underlying the computation of visual motion in the avian tectum. Such mechanisms are critical for information processing in all vertebrates, but have been difficult to elucidate in mammals because of anatomical limitations. We have therefore developed a chick tectal slice preparation, which has features that help us circumvent these limitations. Using single-electrode multi-pulse synaptic stimulation experiments we found that the SGC-I cell responds to synaptic stimulation in a binary manner and its response is phasic in a time dependent probabilistic manner over large time scales. Synaptic inputs at two locations typically interact in a mutually exclusive manner when delivered within the "interaction time" of approximately 30 ms. Then we constructed a model of SGC-I cell and the retinal inputs to examine the role of the observed non-linear cellular properties in shaping the response of SGC-I neurons to assumed retinal representations of dynamic spatiotemporal visual stimuli. We found that by these properties, SGC-I cells can classify different stimuli. Especially without the phasic synaptic signal transfer the model SGC-I cell fails to distinguish between the static stationary stimuli and dynamic spatiotemporal stimuli. Based on one-site synaptic response probability and the assumption of independent neighboring dendritic endings we predicted the response probability of SGC-I cells to multiple synaptic inputs. We tested this independence-based model prediction and found that the independency assumption is not valid. The measured SGC-I response probability to multiple synaptic inputs does not increase with the number of synaptic inputs. The presence of GABAergic horizontal cells in layer 5 suggest an inhibitory effect of these cells on the SGC-I retino-tectal synaptic responses. In our experiment we found that the measured SGC-I response probability to multiple synaptic inputs is reduced when inhibitory tectal circuits are blocked. By predicting the SGC-I response to multiple synaptic inputs based on blocked inhibitory circuitry we found that the response probability is closer to independent situation but not exactly. So there is more than just inhibitory mechanism involved. To characterize the dependency between two neighboring synapses we used 2-site stimulation experiments and measured the effect of one stimulation on a spatially separate synapse. To determine whether this inhibitory mechanism is pre-synaptic or post-synaptic we used chloride channel blocker intracellularly. We saw an increase in response probability when post-synaptic chloride channels are blocked. Finally we found a good agreement between our prediction and experimental results for Poisson spike trains which may be considered more natural stimuli. Only the early stage of SGC-I response is carrying most of the information. Analyzing the SGC-I spike timing and the accuracy of latency is the last part of the thesis.

  10. Solution-processed zinc-tin oxide thin-film transistors with low interfacial trap density and improved performance

    NASA Astrophysics Data System (ADS)

    Lee, Chen-Guan; Dodabalapur, Ananth

    2010-06-01

    Solution-processed amorphous oxide semiconductors are attractive channel materials in thin-film transistors (TFTs) for low-cost electronics. We demonstrate improved performance and uniformity of solution-processed zinc-tin oxide (ZTO) TFTs by optimizing the prebake process for the ZTO precursor film. ZTO prebake process prearranges the dielectric/semiconductor interface and minimizes the performance variation caused by the uneven thermal distribution during annealing process. Prearranging the interface also reduces interfacial trap density and results in improved performance. A mobility of 27.3 cm2/V s, an on/off ratio of 107, and a subthreshold swing of 122 mV/decade have been obtained. Significant improvement in operational stability has also been observed.

  11. Optical trapping for analytical biotechnology.

    PubMed

    Ashok, Praveen C; Dholakia, Kishan

    2012-02-01

    We describe the exciting advances of using optical trapping in the field of analytical biotechnology. This technique has opened up opportunities to manipulate biological particles at the single cell or even at subcellular levels which has allowed an insight into the physical and chemical mechanisms of many biological processes. The ability of this technique to manipulate microparticles and measure pico-Newton forces has found several applications such as understanding the dynamics of biological macromolecules, cell-cell interactions and the micro-rheology of both cells and fluids. Furthermore we may probe and analyse the biological world when combining trapping with analytical techniques such as Raman spectroscopy and imaging. PMID:22154469

  12. Trapping cold molecular hydrogen.

    PubMed

    Seiler, Ch; Hogan, S D; Merkt, F

    2011-11-14

    Translationally cold H(2) molecules excited to non-penetrating |M(J)| = 3 Rydberg states of principal quantum number in the range 21-37 have been decelerated and trapped using time-dependent inhomogeneous electric fields. The |M(J)| = 3 Rydberg states were prepared from the X (1)Σ(+)(u)(v = 0, J = 0) ground state using a resonant three-photon excitation sequence via the B (1)Σ(+)(u)(v = 3, J = 1) and I (1)Π(g) (v = 0, J = 2) intermediate states and circularly polarized laser radiation. The circular polarization of the vacuum ultraviolet radiation used for the B ← X transition was generated by resonance-enhanced four-wave mixing in xenon and the degree of circular polarization was determined to be 96%. To analyse the deceleration and trapping experiments, the Stark effect in Rydberg states of molecular hydrogen was calculated using a matrix diagonalization procedure similar to that presented by Yamakita et al., J. Chem. Phys., 2004, 121, 1419. Particular attention was given to the prediction of zero-field positions of low-l states and of avoided crossings between Rydberg-Stark states with different values of |M(J)|. The calculated Stark maps and probabilities for diabatic traversal of the avoided crossings were used as input to Monte-Carlo particle-trajectory simulations. These simulations provide a quantitatively satisfactory description of the experimental data and demonstrate that particle loss caused by adiabatic traversals of avoided crossings between adjacent |M(J)| = 3 Stark states of H(2) is small at principal quantum numbers beyond n = 25. The main source of trap losses was found to be from collisional processes. Predissociation following the absorption of blackbody radiation is estimated to be the second most important trap-loss mechanism at room temperature, and trap loss by spontaneous emission is negligible under our experimental conditions. PMID:21818497

  13. A concentration-dependent endocytic trap and sink mechanism converts Bmper from an activator to an inhibitor of Bmp signaling.

    PubMed

    Kelley, Rusty; Ren, Rongqin; Pi, Xinchun; Wu, Yaxu; Moreno, Isabel; Willis, Monte; Moser, Martin; Ross, Malcolm; Podkowa, Monika; Attisano, Liliana; Patterson, Cam

    2009-02-23

    Bmper, which is orthologous to Drosophila melanogaster crossveinless 2, is a secreted factor that regulates Bmp activity in a tissue- and stage-dependent manner. Both pro- and anti-Bmp activities have been postulated for Bmper, although the molecular mechanisms through which Bmper affects Bmp signaling are unclear. In this paper, we demonstrate that as molar concentrations of Bmper exceed Bmp4, Bmper dynamically switches from an activator to an inhibitor of Bmp4 signaling. Inhibition of Bmp4 through a novel endocytic trap-and-sink mechanism leads to the efficient degradation of Bmper and Bmp4 by the lysosome. Bmper-mediated internalization of Bmp4 reduces the duration and magnitude of Bmp4-dependent Smad signaling. We also determined that Noggin and Gremlin, but not Chordin, trigger endocytosis of Bmps. This endocytic transport pathway expands the extracellular roles of selective Bmp modulators to include intracellular regulation. This dosage-dependent molecular switch resolves discordances among studies that examine how Bmper regulates Bmp activity and has broad implications for Bmp signal regulation by secreted mediators. PMID:19221194

  14. Structural basis for mechanical force regulation of the adhesin FimH via finger trap-like beta sheet twisting.

    PubMed

    Le Trong, Isolde; Aprikian, Pavel; Kidd, Brian A; Forero-Shelton, Manu; Tchesnokova, Veronika; Rajagopal, Ponni; Rodriguez, Victoria; Interlandi, Gianluca; Klevit, Rachel; Vogel, Viola; Stenkamp, Ronald E; Sokurenko, Evgeni V; Thomas, Wendy E

    2010-05-14

    The Escherichia coli fimbrial adhesive protein, FimH, mediates shear-dependent binding to mannosylated surfaces via force-enhanced allosteric catch bonds, but the underlying structural mechanism was previously unknown. Here we present the crystal structure of FimH incorporated into the multiprotein fimbrial tip, where the anchoring (pilin) domain of FimH interacts with the mannose-binding (lectin) domain and causes a twist in the beta sandwich fold of the latter. This loosens the mannose-binding pocket on the opposite end of the lectin domain, resulting in an inactive low-affinity state of the adhesin. The autoinhibition effect of the pilin domain is removed by application of tensile force across the bond, which separates the domains and causes the lectin domain to untwist and clamp tightly around the ligand like a finger-trap toy. Thus, beta sandwich domains, which are common in multidomain proteins exposed to tensile force in vivo, can undergo drastic allosteric changes and be subjected to mechanical regulation. PMID:20478255

  15. New vanadium trap proven in commercial trials

    SciTech Connect

    Dougan, T.J. ); Alkemade, U.; Lakhanpal, B. ); Boock, L.T. )

    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.

  16. Mechanical-mathematical modeling for landslide process

    NASA Astrophysics Data System (ADS)

    Svalova, V.

    2009-04-01

    Landslides process is one of the most widespread and dangerous processes in the urbanized territories. In Moscow the landslips occupy about 3 % of the most valuable territory of city. There are near 20 places of deep landslides and some hundreds of shallow landslides in Moscow. In Russia many towns are located near rivers on high coastal sides. There are many churches and historical buildings on high costs of Volga River and Moscow River. The organization of monitoring is necessary for maintenance of normal functioning of city infrastructure in a coastal zone and duly realization of effective protective actions. Last years the landslide process activization took place in Moscow. The right coast of river Moscow on its significant extent within the limits of city Moscow is struck by deep block landslides with depth up to 90 - 100 m which formation occurred in preglacial time with basis of sliding in Callovian-Oxford clays of Jurassic system on 25 - 30 m below modern level of the river . One of landslide sites is on Vorob'evy mountains, on a high slope of the right coast of the river Moscow with height of 65 m. There is a historical monument - Andreevsky monastery, based in 1648. Also there are the complex of buildings of Presidium of the Russian Academy of Sciences, constructed in 70 - 80th years of 20-th century, bridge with station of underground "Vorob'evy mountain", constructions of sport complexes. Landslide slope is in active condition, and there are many attributes of activization of deep block landslide. In June 2007 a rather big landslide took place there near ski-jump. Another landslide site is in a southeast part of Moscow, occupying the right coast of river Moscow near museum - reserve "Kolomenskoye". The slope in this place has height of 38 - 40 m. Motions of deep landslips have begun from 1960 in connection with construction of collectors. In 70th years of XX century there was a strong activization of a slope with formation of cracks by extent up to 500 m and displacement of a landslide in the plan over 1 m. Last serious activization of a landslide has taken place in 2002 with a motion on 53 cm. Catastrophic activization of the deep blockglide landslide in the area of Khoroshevo in Moscow took place in 2006-2007. A crack of 330 m long appeared in the old sliding circus, along which a new 220 m long creeping block was separated from the plateau and began sinking with a displaced surface of the plateau reaching to 12 m. Such activization of the landslide process was not observed in Moscow since mid XIX century. The sliding area of Khoroshevo was stable during long time without manifestations of activity. Revealing of the reasons of deformation and development of ways of protection from deep landslide motions is extremely actual and difficult problem which decision is necessary for preservation of valuable historical monuments and modern city constructions. The reasons of activization and protective measures are discussed. Structure of monitoring system for urban territories is elaborated. Mechanical-mathematical model of high viscous fluid was used for modeling of matter behavior on landslide slopes. Equation of continuity and an approximated equation of the Navier-Stockes for slow motions in a thin layer were used. The results of modelling give possibility to define the place of highest velocity on landslide surface, which could be the best place for monitoring post position. Model can be used for calibration of monitoring equipment and gives possibility to investigate some fundamental aspects of matter movement on landslide slope.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    Dlger, 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

  19. 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...

  20. KINETICS AND MECHANISMS OF SOIL BIOGEOCHEMICAL PROCESSES

    EPA Science Inventory

    The application of kinetic studies to soil chemistry is useful to determine reaction mechanisms and fate of nutrients and environmental contaminants. How deeply one wishes to query the mechanism depends on the detail sought. Reactions that involve chemical species in more than on...

  1. Theoretical study of molecular mechanism of binding TRAP220 coactivator to Retinoid X Receptor alpha, activated by 9-cis retinoic acid

    PubMed Central

    Kurcinski, Mateusz; Kolinski, Andrzej

    2010-01-01

    Study on molecular mechanism of conformational reorientation of RXR-alpha ligand binding domain is presented. We employed CABS - a reduced model of protein dynamics to model folding pathways of binding 9-cis retinoic acid to apo-RXR molecule and TRAP220 peptide fragment to the holo form. Based on obtained results we also propose a sequential model of RXR activation by 9-cis retinoic acid and TRAP220 coactivator. Methodology presented here may be used for investigation of binding pathways of other NR/hormone/cofactor sets. PMID:20398753

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

    SciTech Connect

    Derevianko, Andrei

    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.

  3. Quantitative image processing in fluid mechanics

    NASA Technical Reports Server (NTRS)

    Hesselink, Lambertus; Helman, James; Ning, Paul

    1992-01-01

    The current status of digital image processing in fluid flow research is reviewed. In particular, attention is given to a comprehensive approach to the extraction of quantitative data from multivariate databases and examples of recent developments. The discussion covers numerical simulations and experiments, data processing, generation and dissemination of knowledge, traditional image processing, hybrid processing, fluid flow vector field topology, and isosurface analysis using Marching Cubes.

  4. Process for predicting structural performance of mechanical systems

    DOEpatents

    Gardner, David R.; Hendrickson, Bruce A.; Plimpton, Steven J.; Attaway, Stephen W.; Heinstein, Martin W.; Vaughan, Courtenay T.

    1998-01-01

    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.

  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. 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)

  7. The neural mechanism underlying ordinal numerosity processing.

    PubMed

    Gebuis, Titia; Reynvoet, Bert

    2014-05-01

    Changes in the sensory properties of numerosity stimuli have a direct effect on the outcomes of nonsymbolic number tasks. This suggests a prominent role of sensory properties in numerosity processing. However, the current consensus holds that numerosity is processed independent of its sensory properties. To investigate the role of sensory cues in ordinal number processes, we manipulated both dimensions orthogonally. Participants passively viewed the stimuli while their brain activity was measured using EEG. The results revealed an interaction between numerosity and its sensory properties in the absence of main effects. Different neural responses were present for trials where numerosity and sensory cues changed in the same direction compared with trials where they changed in opposite directions. These results show that the sensory cues are expected to change in concert with numerosity and support the notion that the visual cues are taken into account when judging numerosity. PMID:24345168

  8. On Heat in a Quantum Mechanical Process

    NASA Astrophysics Data System (ADS)

    Deesuwan, Tanapat; Anders, Janet

    2013-05-01

    Heat is the portion of energy exchange between systems in thermodynamic process which, unlike work, is always associated with the change of the entropies of the systems. In the context of quantum thermodynamics, heat process is described by an incoherent generalised quantum evolution, which is a map between two quantum states that does not preserve the entropy. Based on an information-theoretic reasoning, we propose that heat involving in a general quantum thermodynamic process can be separated into two types: one that is due to the unital subclass of the evolutions and another one that is due to the others. According to these categories, we show how the former type of heat can be incorporated into Jarzynski equality, resulting in a generalised version of the equality. We also derive a Jarzynski inequality which incorporates all heat into the picture and show that this situation is just equivalent to the presence of Maxwell's demon.

  9. Reactive atomization and deposition process: Fundamental mechanisms

    NASA Astrophysics Data System (ADS)

    Lin, Yaojun

    A modification of spray forming process, namely reactive atomization and deposition (RAD) process, where a reactive gas or gas mixture (e.g., O 2-N2) is used to replace an inert gas, was investigated. First, oxidation behavior during RAD process was numerically analyzed. It is shown that, the overall volume fraction of oxides in the RAD material increases with increasing the atomization pressure, the pouring temperature and the O2 concentration and decreasing the melt flow rate. Second, the influence of in-situ reactions on grain size during RAD process was investigated. By analyzing the influence of in-situ reactions on nucleation behavior during flight and deposition (numerically), as well as on grain coarsening during slow solidification of the remaining liquid phase and grain growth during the solid phase cooling (experimentally), it is predicted that, under the same processing conditions, average grain size in the RAD material is slightly smaller than that in the material processed by spray deposition using N 2 (SDN). Third, size, distribution and morphology of oxides in as-sprayed RAD materials were experimentally studied. It is shown that, oxides exhibit a thin-plate morphology and are distributed at the three typical spatial locations with a dimension scale on an order from tenths of micrometers to micrometers. Fourth, an analytical model was established to describe the oxide fragmentation in the deposition stage during RAD process. With an assumption of disc-shaped oxide dispersoids, the following dimension scales of oxide dispersoids in as-sprayed materials are predicted: on an order from tenths of micrometers to micrometers in diameter and tens of nanometers in thickness. Fifth, an analytical model was established to describe the oxide fragmentation during working processes in a RAD material. It is predicted that, in the worked RAD materials, oxide dispersoid discs exhibit a size scale on an order of tens of nanometers for both diameter and thickness, under typical working conditions. Ultra-high deformation may fragment oxides into ultra-fine dispersoids with a size scale on an order of nanometers. Finally, thermal stability of RAD 5083 Al is investigated via measurements of microhardness and tensile properties. The experimental data indicate a higher thermal stability for RAD 5083 Al relative to 5DN and commercial 5083 Al.

  10. Fluid mechanical issues in polymer processing

    SciTech Connect

    Denn, M.M.

    1987-10-01

    Microstructure in polymers is developed during shaping operations which are carried out in the fluid state. Propagation of the large stresses caused by singularities associated with the flow of viscoelastic liquids near corners and lips is a limiting factor in the numerical solution of processing flows; the strength of the singularity is unknown. There is considerable evidence to indicate that the no-slip boundary condition is inappropriate in polymer processing flows, but the proper replacement has not been established. Other significant issues include flow instabilities and the analysis of the flow of anisotropic liquids. 21 refs.

  11. 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

  12. Production of the midgap electron trap (EL2) in molecular-beam-epitaxial GaAs by rapid thermal processing

    NASA Astrophysics Data System (ADS)

    Kitagawa, Akio; Usami, Akira; Wada, Takao; Tokuda, Yutaka; Kano, Hiroyuki

    1987-02-01

    Rapid thermal processing (RTP) using halogen lamps for molecular-beam-epitaxial (MBE) n-GaAs layers was investigated by deep-level transient spectroscopy. RTP was performed at 800 C for 6 s with proximity capping method. It was found that the Ec -0.82 eV electron trap (EL2) was produced by RTP. The depth profile of EL2 was flat. The spatial variations of EL2 produced by RTP were observed across the MBE layers. The EL2 concentration increased by about two orders of magnitude toward the edge from the center of the samples (1816 mm2). It was thought that the spatial distribution of EL2 corresponded to that of thermal stress induced by RTP.

  13. Study of dynamical process of heat denaturation in optically trapped single microorganisms by near-infrared Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Xie, Changan; Li, Yong-qing; Tang, Wei; Newton, Ronald J.

    2003-11-01

    The development of laser traps has made it possible to investigate single cells and record real-time Raman spectra during a heat-denaturation process when the temperature of the surrounding medium is increased. Large changes in the phenylalanine band (1004 cm-1) of near-infrared spectra between living and heat-treated cells were observed in yeast and Escerichia coli and Enterobacter aerogenes bacteria. This change appears to reflect the change in environment of phenylalanine as proteins within the cells unfold as a result of increasing temperatures. As a comparison, we measured Raman spectra of native and heat-denatured solutions of bovine serum albumin proteins, and a similar change in the phenylalanine band of spectra was observed. In addition, we measured Raman spectra of native and heat-treated solutions of pure phenylalanine molecules; no observable difference in vibrational spectra was observed. These findings may make it possible to study conformational changes in proteins within single cells.

  14. Some contribution to process zone fracture mechanics

    NASA Astrophysics Data System (ADS)

    Miyamoto, H.; Kikuchi, M.; Kubo, M.

    1990-09-01

    The mechanism of the ductile fracture is studied theoretically for the Al Alloy 7075-T6 specimens. A model for the interaction of a crack tip with a void nearby is analyzed by using the Modified Gurson's Model. Taking fracture criterion into consideration, the analysis of a crack propagation is carried out and besides the distribution of the equivalent plastic strain, the void volume fraction f and the localization are obtained. Microcracks nucleate on the ligament between crack and void, and grow and coalesce each other, and at last the main crack thus formed coalesces with the void and the coalescence of the crack and void is completed. And these phenomenon occurs in the localized region. The initiation of the microcrack of 7075 occurs at small J and the microcrack penetration between crack and void occurs at larger J, and the propagation does not occur smoothly. These results coincide with the results of the experiments by FRASTA (FRActure Surface Topographic Analysis) and Fractography.

  15. Ultra-fast underwater suction traps

    PubMed Central

    Vincent, Olivier; Weikopf, 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 speedfar above human visual perceptionimpeded 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 520 h and reset actively to their ready-to-catch condition. PMID:21325323

  16. Laser hardening process simulation for mechanical parts

    NASA Astrophysics Data System (ADS)

    Tani, G.; Orazi, L.; Fortunato, A.; Campana, G.; Cuccolini, G.

    2007-02-01

    In this paper a numerical simulation of laser hardening process is presented. The Finite Difference Method (FDM) was used to solve the heat transfer and the carbon diffusion equations for a defined workpiece geometry. The model is able to predict the thermal cycle into the target material, the phase transformations and the resulting micro-structures according to the laser parameters, the workpiece dimensions and the physical properties of the workpiece. The effects of the overlapping tracks of the laser beam on the resulting micro-structures is also considered. The initial workpiece micro-structure is taken into account in the simulation by a digitized photomicrograph of the ferrite perlite distribution before the thermal cycle. Experimental tests were realized on a C43 plate and the good agreement between the theoretical and experimental results is shown.

  17. 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. 100C. 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.

  18. LETTER TO THE EDITOR: Relaxation processes and entropic traps in the Backgammon model

    NASA Astrophysics Data System (ADS)

    Franz, Silvio; Ritort, Felix

    1997-06-01

    We examine the density - density correlation function in a model recently proposed to study the effect of entropy barriers in glassy dynamics. We find that the relaxation proceeds in two steps with a fast beta process followed by alpha relaxation. The results are physically interpreted in the context of an adiabatic approximation which allows one to separate the two processes and define an effective temperature in the off-equilibrium dynamics of the model. We investigate the behaviour of the response function associated with the density and find violations of the fluctuation dissipation theorem.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  20. 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.

  1. Crystal structures of nitroalkane oxidase: insights into the reaction mechanism from a covalent complex of the flavoenzyme trapped during turnover.

    PubMed

    Nagpal, Akanksha; Valley, Michael P; Fitzpatrick, Paul F; Orville, Allen M

    2006-01-31

    Nitroalkane oxidase (NAO) from Fusarium oxysporum catalyzes the oxidation of neutral nitroalkanes to the corresponding aldehydes or ketones with the production of H(2)O(2) 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 A 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 A resolution. The c axis for the trigonal space group of oxidized NAO is 485 A, and there are six subunits (1(1)/(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(ox)). The active-site structures of E(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 A. 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. PMID:16430210

  2. 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.

  3. Electrocatalytic Polysulfide Traps for Controlling Redox Shuttle Process of Li-S Batteries.

    PubMed

    Al Salem, Hesham; Babu, Ganguli; Rao, Chitturi V; Arava, Leela Mohana Reddy

    2015-09-16

    Stabilizing the polysulfide shuttle while ensuring high sulfur loading holds the key to realizing high theoretical energy of lithium-sulfur (Li-S) batteries. Herein, we present an electrocatalysis approach to demonstrate preferential adsorption of a soluble polysulfide species, formed during discharge process, toward the catalyst anchored sites of graphene and their efficient transformation to long-chain polysulfides in the subsequent redox process. Uniform dispersion of catalyst nanoparticles on graphene layers has shown a 40% enhancement in the specific capacity over pristine graphene and stability over 100 cycles with a Coulombic efficiency of 99.3% at a current rate of 0.2 C. Interaction between electrocatalyst and polysulfides has been evaluated by conducting X-ray photoelectron spectroscopy and electron microscopy studies at various electrochemical conditions. PMID:26331670

  4. Light-Harvesting Mechanism of Bacteria Exploits a Critical Interplay between the Dynamics of Transport and Trapping

    NASA Astrophysics Data System (ADS)

    Caycedo-Soler, Felipe; Rodrguez, Ferney J.; Quiroga, Luis; Johnson, Neil F.

    2010-04-01

    Light-harvesting bacteria Rhodospirillum photometricum were recently found to adopt strikingly different architectures depending on illumination conditions. We present analytic and numerical calculations which explain this observation by quantifying a dynamical interplay between excitation transfer kinetics and reaction center cycling. High light-intensity membranes exploit dissipation as a photoprotective mechanism, thereby safeguarding a steady supply of chemical energy, while low light-intensity membranes efficiently process unused illumination intensity by channeling it to open reaction centers. More generally, our analysis elucidates and quantifies the trade-offs in natural network design for solar energy conversion.

  5. Reduction of the interfacial trap density of indium-oxide thin film transistors by incorporation of hafnium and annealing process

    SciTech Connect

    Lin, Meng-Fang E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Gao, Xu; Mitoma, Nobuhiko; Kizu, Takio; Ou-Yang, Wei; Tsukagoshi, Kazuhito E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Aikawa, Shinya; Nabatame, Toshihide

    2015-01-15

    The stable operation of transistors under a positive bias stress (PBS) is achieved using Hf incorporated into InO{sub x}-based thin films processed at relatively low temperatures (150 to 250 °C). The mobilities of the Hf-InO{sub x} thin-film transistors (TFTs) are higher than 8 cm{sup 2}/Vs. The TFTs not only have negligible degradation in the mobility and a small shift in the threshold voltage under PBS for 60 h, but they are also thermally stable at 85 °C in air, without the need for a passivation layer. The Hf-InO{sub x} TFT can be stable even annealed at 150 °C for positive bias temperature stability (PBTS). A higher stability is achieved by annealing the TFTs at 250 °C, originating from a reduction in the trap density at the Hf-InO{sub x}/gate insulator interface. The knowledge obtained here will aid in the realization of stable TFTs processed at low temperatures.

  6. 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.

  7. 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

  8. Motional Ion Heating Rate Measurements over a Range of Trap Frequencies and Temperatures

    NASA Astrophysics Data System (ADS)

    Bruzewicz, Colin; McConnell, Robert; Sage, Jeremy; Chiaverini, John

    2015-05-01

    Anomalous motional heating limits high-fidelity two-qubit gate operations in large-scale trapped-ion quantum computation. To examine the possible mechanisms driving this process, we present detailed measurements of the heating rate of a single trapped ion over a range of trap frequencies and temperatures. We compare these results to predictions given by available theoretical electric-field noise models and constrain a subset of these models based on the observed trap frequency and temperature scaling interdependence. Additionally, we report on recent efforts to mitigate motional state heating with electrode surface treatments, such as in situ local trap chip baking and plasma cleaning.

  9. Charge-trap effects of 2D DNA nanostructures implanted in solution-processed InGaZnO thin-film transistor

    NASA Astrophysics Data System (ADS)

    Lee, Keun Woo; Kim, Kyung Min; Kim, Si Joon; Reddy Dugasani, Sreekantha; Lee, Junwye; Park, Sung Ha; Kim, Hyun Jae

    2013-05-01

    A double crossover (DX) tile-based 2D DNA nanostructure was fabricated and implanted successfully in solution-processed InGaZnO thin film transistor. Observations indicated that the DNA nanostructure plays an important role as a trap charge centre under high electric field in the memory device. At positive gate voltage the memory device with the DNA shows appreciable trapped charge and at negative gate voltage reveals detrapped negative charge characteristics. Consequently, various dimensional DNA nanostructures may play a central role in nanoscale devices and applications in the near future.

  10. Chemical Reactivity in Mechanically Ground Quartz Relevant to Impact Processes

    NASA Astrophysics Data System (ADS)

    Rask, J. C.; McCrossin, C.; Loftus, D. J.

    2011-03-01

    To understand how impact processes may affect the chemical reactivity and toxicity of regolith and dust, we have tested a variety of mechanical grinding methods for quartz and other planetary analog materials.

  11. Transprocessing: A Proposed Neurobiological Mechanism of Psychotherapeutic Processing

    PubMed Central

    Bota, Robert G.

    2014-01-01

    How does the human brain absorb information and turn it into skills of its own in psychotherapy? In an attempt to answer this question, the authors will review the intricacies of processing channels in psychotherapy and propose the term transprocessing (as in transduction and processing combined) for the underlying mechanisms. Through transprocessing the brain processes multimodal memories and creates reparative solutions in the course of psychotherapy. Transprocessing is proposed as a stage-sequenced mechanism of deconstruction of engrained patterns of response. Through psychotherapy, emotional-cognitive reintegration and its consolidation is accomplished. This process is mediated by cellular and neural plasticity changes. PMID:25478135

  12. Negative bias temperature instability of SiC MOSFET induced by interface trap assisted hole trapping

    NASA Astrophysics Data System (ADS)

    Yen, Cheng-Tyng; Hung, Chien-Chung; Hung, Hsiang-Ting; Lee, Chwan-Ying; Lee, Lurng-Shehng; Huang, Yao-Feng; Hsu, Fu-Jen

    2016-01-01

    We investigated the negative bias temperature instability (NBTI) characteristics of 4H-SiC metal oxide semiconductor field effect transistor (MOSFET) and metal oxide semiconductor capacitor (MOSCAP). The shift of threshold voltage approached saturation with time, and the different magnitude of mid-gap voltage shift with different starting biases observed in capacitance-voltage (CV) curves taken from MOSCAP and MOSFET suggested that the hole trapping was the primary mechanism contributing to the NBTI in this study. The trend of mid-gap voltage shift with starting bias and threshold voltage shift with stress bias showed steep change before -10 V and approached saturation after -10 V which can be explained by a process where the hole trapping was assisted by positively charged interface states. The positively charged interface states may have acted as an intermediate state which reduced the overall energy barrier and facilitated the process of hole trapping. The split-CV sweeps with 0 s and 655 s of hold time were essentially overlapped which was consistent with the time evolution characteristic of hole trapping and supported the interface trap assisted hole trapping mechanism.

  13. Mechanization and automation of production processes in turbine building

    NASA Astrophysics Data System (ADS)

    Slobodyanyuk, V. P.

    1984-02-01

    Specialists at the All-Union Institute of Planning and Technology of Energy Machine Building are working on the problem of mechanization and automation of production processes. One of the major technological processes being worked on is the production of welded units. At the present time the Institute has designed a centralized cutting and manufacturing shop in use at several metallurgical plants, clamping devices for materials hoists based on permanent magnets, a program controlled installation for driving shaped apertures in welded diaphragm rims and an automated system for planning technological processes involved in manufacturing operations. Even in the manufacture of such individualized devices as turbines, mechanization and automation of production processes are economically justified. During the 11th Five Year Plan, the Institute will continue to develop progressive technological processes and equipment for precise shaping of turbine blade blanks, mechanical working of parts of steam, gas and hydraulic turbines, as well as nuclear powerplant turbines.

  14. Universal Expression of Efficiency at Maximum Power: A Quantum-Mechanical Brayton Engine Working with a Single Particle Confined in a Power-Law Trap

    NASA Astrophysics Data System (ADS)

    Ye, Zhuo-Lin; Li, Wei-Sheng; Lai, Yi-Ming; He, Ji-Zhou; Wang, Jian-Hui

    2015-12-01

    We propose a quantum-mechanical Brayton engine model that works between two superposed states, employing a single particle confined in an arbitrary power-law trap as the working substance. Applying the superposition principle, we obtain the explicit expressions of the power and efficiency, and find that the efficiency at maximum power is bounded from above by the function: ?+ = ?/(? + 1), with ? being a potential-dependent exponent. Supported by the National Natural Science Foundation of China under Grant Nos. 11505091, 11265010, and 11365015, and the Jiangxi Provincial Natural Science Foundation under Grant No. 20132BAB212009

  15. Opiate reinforcement processes: re-assembling multiple mechanisms.

    PubMed

    Bozarth, M A

    1994-11-01

    Opiate reinforcement processes can be described within the context of operant conditioning theory. Both positive and negative reinforcing effects may motivate drug-taking behavior, although the strongest evidence attributes drug-taking to a simple positive reinforcement process. Empirical research has focused largely on a positive reinforcement mechanism involving the ventral tegmental dopamine system, but three additional reinforcement mechanisms can be argued on logical grounds. These other mechanisms involve neuroadaptive changes produced by chronic opiate administration and may contribute to the strong motivational impact of opiates following long-term drug use. PMID:7841852

  16. Investigation of oxidation process of mechanically activated ultrafine iron powders

    NASA Astrophysics Data System (ADS)

    Lysenko, E. N.; Nikolaev, E. V.; Vlasov, V. A.; Zhuravkov, S. P.

    2016-02-01

    The oxidation of mechanically activated ultrafine iron powders was studied using X- ray powder diffraction and thermogravimetric analyzes. The powders with average particles size of 100 nm were made by the electric explosion of wire, and were subjected to mechanical activation in planetary ball mill for 15 and 40 minutes. It was shown that a certain amount of FeO phase is formed during mechanical activation of ultrafine iron powders. According to thermogravimetric analysis, the oxidation process of non-milled ultrafine iron powders is a complex process and occurs in three stages. The preliminary mechanical activation of powders considerably changes the nature of the iron powders oxidation, leads to increasing in the temperature of oxidation onset and shifts the reaction to higher temperatures. For the milled powders, the oxidation is more simple process and occurs in a single step.

  17. 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.

  18. Energy of charged states in the acetanilide crystal: Trapping of charge-transfer states at vacancies as a possible mechanism for optical damage

    NASA Astrophysics Data System (ADS)

    Tsiaousis, D.; Munn, R. W.

    2004-04-01

    Calculations for the acetanilide crystal yield the effective polarizability (16.6 Å3), local electric field tensor, effective dipole moment (5.41 D), and dipole-dipole energy (-12.8 kJ/mol). Fourier-transform techniques are used to calculate the polarization energy P for a single charge in the perfect crystal (-1.16 eV); the charge-dipole energy WD is zero if the crystal carries no bulk dipole moment. Polarization energies for charge-transfer (CT) pairs combine with the Coulomb energy EC to give the screened Coulomb energy Escr; screening is nearly isotropic, with Escr≈EC/2.7. For CT pairs WD reduces to a term δWD arising from the interaction of the charge on each ion with the change in dipole moment on the other ion relative to the neutral molecule. The dipole moments calculated by density-functional theory methods with the B3LYP functional at the 6-311++G** level are 3.62 D for the neutral molecule, changing to 7.13 D and 4.38 D for the anion and cation, relative to the center of mass. Because of the large change in the anion, δWD reaches -0.9 eV and modifies the sequence of CT energies markedly from that of Escr, giving the lowest two CT pairs at -1.98 eV and -1.41 eV. The changes in P and WD near a vacancy are calculated; WD changes for the individual charges because the vacancy removes a dipole moment and modifies the crystal dielectric response, but δWD and EC do not change. A vacancy yields a positive change ΔP that scatters a charge or CT pair, but the change ΔWD can be negative and large enough to outweigh ΔP, yielding traps with depths that can exceed 150 meV for single charges and for CT pairs. Divacancies yield traps with depths nearly equal to the sum of those produced by the separate vacancies and so they can exceed 300 meV. These results are consistent with a mechanism of optical damage in which vacancies trap optically generated CT pairs that recombine and release energy; this can disrupt the lattice around the vacancy, thereby favoring trapping and recombination of CT pairs generated by subsequent photon absorption, leading to further lattice disruption. Revisions to previous calculations on trapping of CT pairs in anthracene are reported.

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

    SciTech Connect

    Ciurea, Magdalena Lidia Lazanu, Sorina

    2014-10-06

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

  20. Carnivorous plants: trapping, digesting and absorbing all in one.

    PubMed

    Brownlee, Colin

    2013-09-01

    The Venus flytrap digests and absorbs its prey, but how does it coordinate digestion and absorption to maximise the efficiency of this highly evolved mechanism? A new study that combines direct recordings from cells within the trap along with molecular characterization of nutrient transport reveals a complex and coordinated suite of mechanisms that underlie this elegant process. PMID:24028948

  1. 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.

  2. Enhanced Ion Utilization Efficiency Using an Electrodynamic Ion Funnel Trap as an Injection Mechanism for Ion Mobility Spectrometry

    PubMed Central

    Clowers, Brian H.; Ibrahim, Yehia; Prior, David C.; Danielson, William F.; Belov, Mikhail; Smith, Richard D.

    2008-01-01

    Conventional ion mobility spectrometers that sample ion packets from continuous sources have traditionally been constrained by an inherently low duty cycle. As such, ion utilization efficiencies have been limited to <1% in order to maintain instrumental resolving power. Using a modified electrodynamic ion funnel, we demonstrated the ability to accumulate, store, and eject ions in conjunction with ion mobility spectrometry (IMS), which elevated the charge density of the ion packets ejected from the ion funnel trap (IFT) and provided a considerable increase in the overall ion utilization efficiency of the IMS instrument. A 7-fold increase in signal intensity was revealed by comparing continuous ion beam current with the amplitude of the pulsed ion current in IFT-IMS experiments using a Faraday plate. Additionally, we describe the IFT operating characteristics using a time-of-flight mass spectrometer attached to the IMS drift tube. PMID:18166021

  3. Enhanced ion utilization efficiency using an electrodynamic ion funnel trap as an injection mechanism for ion mobility spectrometry.

    PubMed

    Clowers, Brian H; Ibrahim, Yehia M; Prior, David C; Danielson, William F; Belov, Mikhail E; Smith, Richard D

    2008-02-01

    Conventional ion mobility spectrometers that sample ion packets from continuous sources have traditionally been constrained by an inherently low duty cycle. As such, ion utilization efficiencies have been limited to <1% in order to maintain instrumental resolving power. Using a modified electrodynamic ion funnel, we demonstrated the ability to accumulate, store, and eject ions in conjunction with ion mobility spectrometry (IMS), which elevated the charge density of the ion packets ejected from the ion funnel trap (IFT) and provided a considerable increase in the overall ion utilization efficiency of the IMS instrument. A 7-fold increase in signal intensity was revealed by comparing continuous ion beam current with the amplitude of the pulsed ion current in IFT-IMS experiments using a Faraday plate. Additionally, we describe the IFT operating characteristics using a time-of-flight mass spectrometer attached to the IMS drift tube. PMID:18166021

  4. Experimental investigation of supercritical CO2 trapping mechanisms at the Intermediate Laboratory Scale in well-defined heterogeneous porous media

    DOE PAGESBeta

    Trevisan, Luca; Pini, Ronny; Cihan, Abdullah; Birkholzer, Jens T.; Zhou, Quanlin; Illangasekare, Tissa H.

    2014-12-31

    The heterogeneous nature of typical sedimentary formations can play a major role in the propagation of the CO2 plume, eventually dampening the accumulation of mobile phase underneath the caprock. From core flooding experiments, it is also known that contrasts in capillary threshold pressure due to different pore size can affect the flow paths of the invading and displaced fluids and consequently influence the build- up of non-wetting phase (NWP) at interfaces between geological facies. The full characterization of the geologic variability at all relevant scales and the ability to make observations on the spatial and temporal distribution of the migrationmore » and trapping of supercritical CO2 is not feasible from a practical perspective. To provide insight into the impact of well-defined heterogeneous systems on the flow dynamics and trapping efficiency of supercritical CO2 under drainage and imbibition conditions, we present an experimental investigation at the meter scale conducted in synthetic sand reservoirs packed in a quasi-two-dimensional flow-cell. Two immiscible displacement experiments have been performed to observe the preferential entrapment of NWP in simple heterogeneous porous media. The experiments consisted of an injection, a fluid redistribution, and a forced imbibition stages conducted in an uncorrelated permeability field and a homogeneous base case scenario. We adopted x-ray attenuation analysis as a non-destructive technique that allows a precise measurement of phase saturations throughout the entire flow domain. By comparing a homogeneous and a heterogeneous scenario we have identified some important effects that can be attributed to capillary barriers, such as dampened plume advancement, higher non-wetting phase saturations, larger contact area between the injected and displaced phases, and a larger range of non-wetting phase saturations.« less

  5. Social Information Processing Mechanisms and Victimization: A Literature Review.

    PubMed

    van Reemst, Lisa; Fischer, Tamar F C; Zwirs, Barbara W C

    2016-01-01

    The aim of the current literature review, which is based on 64 empirical studies, was to assess to what extent mechanisms of the Social Information Processing (SIP) model of Crick and Dodge (1994) are related to victimization. The reviewed studies have provided support for the relation between victimization and several social information processing mechanisms, especially the interpretation of cues and self-efficacy (as part of the response decision). The relationship between victimization and other mechanisms, such as the response generation, was only studied in a few articles. Until now research has often focused on just one step of the model, instead of attempting to measure the associations between multiple mechanisms and victimization in multivariate analyses. Such analyses would be interesting to gain more insight into the SIP model and its relationship with victimization. The few available longitudinal studies show that mechanisms both predict victimization (internal locus of control, negative self-evaluations and less assertive response selection) and are predicted by victimization (hostile attribution of intent and negative evaluations of others). Associations between victimization and SIP mechanisms vary across different types and severity of victimization (stronger in personal and severe victimization), and different populations (stronger among young victims). Practice could focus on these stronger associations and the interpretation of cues. More research is needed however, to investigate whether intervention programs that address SIP mechanisms are suitable for victimization and all relevant populations. PMID:25389278

  6. 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

  7. Mechanics of aeolian processes: Soil erosion and dust production

    NASA Technical Reports Server (NTRS)

    Mehrabadi, M. M.

    1989-01-01

    Aeolian (wind) processes occur as a result of atmosphere/land-surface system interactions. A thorough understanding of these processes and their physical/mechanical characterization on a global scale is essential to monitoring global change and, hence, is imperative to the fundamental goal of the Earth observing system (Eos) program. Soil erosion and dust production by wind are of consequence mainly in arid and semi arid regions which cover 36 percent of the Earth's land surface. Some recent models of dust production due to wind erosion of agricultural soils and the mechanics of wind erosion in deserts are reviewed and the difficulties of modeling the aeolian transport are discussed.

  8. Steam trap monitor

    DOEpatents

    Ryan, M.J.

    1987-05-04

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

  9. Processing dependence of mechanical properties of metallic glass nanowires

    SciTech Connect

    Zhang, Qi; Li, Mo; Li, Qi-Kai

    2015-02-16

    Compared to their crystalline counterparts, nanowires made of metallic glass have not only superb properties but also remarkable processing ability. They can be processed easily and cheaply like plastics via a wide range of methods. To date, the underlying mechanisms of how these different processing routes affect the wires' properties as well as the atomic structure remains largely unknown. Here, by using atomistic modeling, we show that different processing methods can greatly influence the mechanical properties. The nanowires made via focused ion beam milling and embossing exhibit higher strength but localized plastic deformation, whereas that made by casting from liquid shows excellent ductility with homogeneous deformation but reduced strength. The different responses are reflected sensitively in the underlying atomic structure and packing density, some of which have been observed experimentally. The presence of the gradient of alloy concentration and surface effect will be discussed.

  10. 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.

  11. Hemispheric Differences in the Recruitment of Semantic Processing Mechanisms

    ERIC Educational Resources Information Center

    Kandhadai, Padmapriya; Federmeier, Kara D.

    2010-01-01

    This study examined how the two cerebral hemispheres recruit semantic processing mechanisms by combining event-related potential measures and visual half-field methods in a word priming paradigm in which semantic strength and predictability were manipulated using lexically associated word pairs. Activation patterns on the late positive complex

  12. Mechanism of metal nanowire formation via the polyol process

    NASA Astrophysics Data System (ADS)

    Choi, Yo-Han; Chae, Young-Soo; Lee, Jong-Hyuk; Kwon, Yong-woo; Kim, Yong-Seog

    2015-09-01

    The morphology and capping layer of Ag-nanowires prepared using the polyol process were examined to understand their formation mechanism. Cu-nanowires prepared from the salt reduction process were examined as well. The observation suggests that the nucleation and growth of the nanowires might have been controlled by thermodynamics, rather than by the kinetics of metal atom diffusion through the capping layer. In this study, a thermodynamic model was proposed to account for the limited radial growth of the nanowires during the process. [Figure not available: see fulltext.

  13. Rotating Saddle Paul Trap.

    ERIC Educational Resources Information Center

    Rueckner, Wolfgang; And Others

    1995-01-01

    Describes a demonstration in which a ball is placed in an unstable position on a saddle shape. The ball becomes stable when it is rotated above some threshold angular velocity. The demonstration is a mechanical analog of confining a particle in a "Paul Trap". (DDR)

  14. 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

  15. Trapped-electron runaway effect

    NASA Astrophysics Data System (ADS)

    Nilsson, E.; Decker, J.; Fisch, N. J.; Peysson, Y.

    2015-08-01

    In a tokamak, trapped electrons subject to a strong electric field cannot run away immediately, because their parallel velocity does not increase over a bounce period. However, they do pinch toward the tokamak center. As they pinch toward the center, the trapping cone becomes more narrow, so eventually they can be detrapped and run away. When they run away, trapped electrons will have a very different signature from circulating electrons subject to the Dreicer mechanism. The characteristics of what are called trapped-electron runaways are identified and quantified, including their distinguishable perpendicular velocity spectrum and radial extent.

  16. Comparing Ultrasound and Mechanical Steering in a Biodiesel Production Process

    NASA Astrophysics Data System (ADS)

    Costa-Felix, Rodrigo P. B.; Ferreira, Jerusa R. L.

    The analysis of the kinetics of the transesterification reaction is crucial to compare different routes or routes with different catalysts or reaction accelerators. The use of ultrasound is considereda method for accelerating the biodiesel production. However, little effort has been done and is reported in the literature about how and under what conditions the use of ultrasound really speeds up the process, or the conditions under which its use is unnecessary or even harmful, burdening the process. Two dissimilar energy injections into a typical route were tested: ultrasound (@ 1 MHz and no heating) and mechanical steering (with heating), both applied in an 8:1 ratio of soybean oil and methanol, adding 1% of KOH as catalyzer. As results, during the first 10 minutes of reaction ultrasound showed unbearable effect on the transesterification, whilst mechanical steering and heating achieved almost 70% of conversion ratio. However, during the following 10 minutes, the mechanical steering and heating got nothing more than 80% of conversion, a considerable less efficient process than ultrasound assisted one, which achieved more than 90%. The straightforward explanation is that ultrasound continually inserts energy in a slower rate, what can result in a more stable conversion scenario. On the other hand, mechanical steering and heating provides more energy at a glance, but cannot push the final conversion rate beyond a limit, as the transesterification is a double-way chemical process. The instability mechanical steering and heating settles in the reaction medium pulls the components back to their original states more than pushes than to the converted equilibrium state of the matter.

  17. 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.

  18. 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, χ 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 (χ ˆ ≈ 0) to very high connectivity (χ 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.

  19. Characterization of a Crossed 1071 nm Dual Species Dipole Trap

    NASA Astrophysics Data System (ADS)

    Tallant, Jonathan; Menegatti, Carlos; Marangoni, Bruno; Marcassa, Luis

    2013-05-01

    Several experiments involving heteronuclear molecules rely on dense atomic samples. In our experiment, overlapped magneto-optical traps (MOTs) containing 39K and 85Rb are used to load a broadband crossed dipole trap. A cooling sequence is applied to the MOTs to load the dipole trap. Several parameters are varied during the cooling sequence to optimize the loading of both species into the dipole trap with equal densities. The results of the optimization process are presented. We find that ramping the laser power during the potassium loading improves the number of potassium atoms that are captured by the dipole trap. The need for this ramp is supported by calculations of the ac Stark shift of the 4p3/2 hyperfine manifold of states. Finally, lifetimes of both species in the dipole trap are presented. The lifetimes show a fast decay at early times which suggests a density dependent, few-body loss mechanism. Evidence is presented suggesting the mechanism is photoassociation of deeply bound KRb molecules by the 1071 nm trapping light. This work was supported by Fapesp and INCT-IQ.

  20. INSECT TRAP

    Technology Transfer Automated Retrieval System (TEKTRAN)

    FLYBRELLA describes a lightweight inexpensive trap that can be hung like an upside-down umbrella in prominent locations where the house flies rest. It consists of a perforated transparent tube that house flies were found to enter readily, containing a strip of rapid-acting sugar-based toxicant. An i...

  1. Bee Trap

    USGS Multimedia Gallery

    Researchers emptying a set of traps. The team uses a hand-net to capture larger bees observed along the transects. The same approach is used in the non-powerline land cover types to survey bees in those land covers....

  2. 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.

  3. Quantum processes as a mechanism in olfaction for smell recognition?

    NASA Astrophysics Data System (ADS)

    Brookes, Jennifer

    2011-03-01

    The physics of smell is not well understood. The biological processes that occur following a signalling event are well understood (Buck 1991). However, the reasons how and why a signalling event occurs when a particular smell molecule and receptor combination is made, remains un-established. Luca Turin proposes a signalling mechanism which determines smell molecules by quantum mechanics (Turin 1996). Investigation of this mechanism shows it to be physically robust (Brookes,et al, 2007), and consequences of the theory provides quantitative measurements of smell and interesting potential experiments that may determine whether the recognition of smell is a quantum event. Brookes, J.C, Hartoutsiou, F, Horsfield, A.P and Stoneham, A.M. (2007). Physical Review Letters 98, no. 3 038101 Buck, L. (1991) Cell, 65, no.1 (4): 175-187. Turin, L. (1996) Chemical Sences 21, no 6. 773-791 With many thanks to the Wellcome Trust.

  4. 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.

  5. 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.

  6. Process entanglement as a neuronal anchorage mechanism to rough surfaces

    NASA Astrophysics Data System (ADS)

    Sorkin, Raya; Greenbaum, Alon; David-Pur, Moshe; Anava, Sarit; Ayali, Amir; Ben-Jacob, Eshel; Hanein, Yael

    2009-01-01

    The organization of neurons and glia cells on substrates composed of pristine carbon nanotube islands was investigated using high resolution scanning electron microscopy, immunostaining and confocal microscopy. Neurons were found bound and preferentially anchored to the rough surfaces; moreover, the morphology of the neuronal processes on the small, isolated islands of high density carbon nanotubes was found to be conspicuously curled and entangled. We further demonstrate that the roughness of the surface must match the diameter of the neuronal processes in order to allow them to bind. The results presented here suggest that entanglement, a mechanical effect, may constitute an additional mechanism by which neurons (and possibly other cell types) anchor themselves to rough surfaces. Understanding the nature of the interface between neurons and carbon nanotubes is essential to effectively harness carbon nanotube technology in neurological applications such as neuro-prosthetic and retinal electrodes.

  7. Active Cellular Mechanics and Information Processing in the Living Cell

    NASA Astrophysics Data System (ADS)

    Rao, M.

    2014-07-01

    I will present our recent work on the organization of signaling molecules on the surface of living cells. Using novel experimental and theoretical approaches we have found that many cell surface receptors are organized as dynamic clusters driven by active currents and stresses generated by the cortical cytoskeleton adjoining the cell surface. We have shown that this organization is optimal for both information processing and computation. In connecting active mechanics in the cell with information processing and computation, we bring together two of the seminal works of Alan Turing.

  8. 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

  9. UNDERSTANDING OLIVINE CO2 MINERAL SEQUESTRATION MECHANISMS AT THE ATOMIC LEVEL: OPTIMIZING REACTION PROCESS DESIGN

    SciTech Connect

    M.J. McKelvy; H. Bearat; A.V.G. Chizmeshya; R. Nunez; R.W. Carpenter

    2003-08-01

    Carbonation of Mg-rich minerals offers an intriguing candidate carbon sequestration process technology, which can provide large-scale CO{sub 2} disposal. Such disposal bypasses many long-term storage problems by (i) providing containment in the form of mineral carbonates that have proven stable over geological time, (ii) generating only environmentally benign materials, and (iii) essentially eliminating the need for continuous site monitoring. The primary challenge for viable process development is reducing process cost. This is the primary focus of the CO{sub 2} Mineral Sequestration Working Group managed by Fossil Energy at DOE, which includes members from the Albany Research Center, Los Alamos National Laboratory, the National Energy Technology Laboratory, Penn State University, Science Applications International Corporation, and the University of Utah, as well as from our research group at Arizona State University. Carbonation of the widely occurring mineral olivine (e.g., forsterite, Mg{sub 2}SiO{sub 4}) is a leading process candidate, which converts CO{sub 2} into the mineral magnesite (MgCO{sub 3}). As olivine carbonation is exothermic, it offers intriguing low-cost potential. Recent studies at the Albany Research Center have found aqueous-solution carbonation is a promising approach. Cost effectively enhancing carbonation reactivity is central to reducing process cost. Many of the mechanisms that impact reactivity occur at the solid/solution interface. Understanding these mechanisms is central to the ability to engineer new and modified processes to enhance carbonation reactivity and lower cost. Herein, we report the results of our UCR I project, which focused on exploring the reaction mechanisms that govern aqueous-solution olivine carbonation using model olivine feedstock materials. Carbonation was found to be a complex process associated with passivating silica layer formation, which includes the trapping of magnesite nanocrystals within the passivating silica layers, cracking and exfoliation of the layers, silica surface migration, olivine etch pit formation, transfer of the Mg and Fe in the olivine into the product carbonate, and the nucleation and growth of magnesite crystals on/in the silica/olivine reaction matrix. These phenomena occur in concert with the large solid volume changes that accompany the carbonation process, which can substantially impact carbonation reactivity. Passivating silica layer formation appears to play a major role in inhibiting carbonation reactivity. New approaches that can mitigate the effectiveness of passivating layer formation may offer intriguing potential to enhance carbonation reactivity and lower process cost.

  10. 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 Parkinsons 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

  11. Mass measurements of isotopes of Nb, Mo, Tc, Ru, and Rh along the ?p- and rp-process paths using the Canadian Penning trap mass spectrometer

    NASA Astrophysics Data System (ADS)

    Fallis, J.; Clark, J. A.; Sharma, K. S.; Savard, G.; Buchinger, F.; Caldwell, S.; Chaudhuri, A.; Crawford, J. E.; Deibel, C. M.; Gulick, S.; Hecht, A. A.; Lascar, D.; Lee, J. K. P.; Levand, A. F.; Li, G.; Lundgren, B. F.; Parikh, A.; Russell, S.; Scholte-van de Vorst, M.; Scielzo, N. D.; Segel, R. E.; Sharma, H.; Sinha, S.; Sternberg, M. G.; Sun, T.; Tanihata, I.; van Schelt, J.; Wang, J. C.; Wang, Y.; Wrede, C.; Zhou, Z.

    2011-10-01

    The reaction paths of two proposed nucleosynthetic processes on the proton-rich side of stability, the rp and ?p processes, pass through a region of isotopes between Mo and Pd where masses had long gone unmeasured. Precise knowledge of the paths and final abundances of these two processes has been limited by the corresponding lack of precision in the proton-separation energies Sp when derived from extrapolated masses. The masses of 18 neutron-deficient isotopes of Nb, Mo, Tc, Ru, and Rh have been measured using the Canadian Penning trap mass spectrometer. Three of the masses presented, 90Mo, 91Mo, and 93Tc, provide the first direct measurement of the masses of these nuclides, and the others provide confirmation of recent measurements using other Penning traps. Included in this work is a measurement of the mass of 87Mo, which differs by 3.7? from the mass presented in the 2003 Atomic Mass Evaluation. This leads to a change in the Sp value of 88Tc which reduces the suppression of flow of the ?p-process path through 87Mo(p,?)88Tc reported following the mass measurement of 88Tc [C. Weber , Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.78.054310 78, 054310 (2008)]. This in turn affects the resulting ?p-process abundances.

  12. Process sampling module coupled with purge and trap-GC-FID for in situ auto-monitoring of volatile organic compounds in wastewater.

    PubMed

    Liu, Hsin-Wang; Liu, Yung-Tsun; Wu, Bei-Zen; Nian, Hung-Chi; Chen, Hsing-Jung; Chiu, Kong-Hwa; Lo, Jiunn-Guang

    2009-12-15

    An automatic sampling device, i.e., process sampling module (PSM), connected with a purge and trap-GC-FID system has been developed for real-time monitoring of VOCs in wastewater. The system was designed to simultaneously monitor 17 compounds, including one polar compound, i.e., acetone, and 16 non-polar compounds. The trapping tube is packed with two adsorbents, Carbopack B and Carbosieve III, to trap target compounds. For the purpose of in situ monitoring, the flush valve of the sampling tube is composed of two two-way valves and a time controller to prevent absorption interference of the residue. The optimal conditions for the analytical system include a 12 min purge time at a temperature of 60 degrees C, and 4 min of desorption time with a desorption temperature of 260 degrees C. Good chromatograms have been obtained with the analytical system even if a cryogenic device and de-misting were not used. The relative standards deviation (RSD) of the system is between 2% and 13.4%, and accuracies between 0.3 and 23.5% have been achieved. The detection limits of the method range from 0.32 to 2.39 ppb. In this system, the four parts, i.e., PSM, P&T, GC, and FID, were simple, reliable and rugged. Also, the interface of these four parts was simple and dependable. PMID:19836571

  13. Disappearance of Barrier Metal during Cu Chemical Mechanical Planarization Processing and Its Mechanism

    NASA Astrophysics Data System (ADS)

    Asano, Hiroshi; Yasui, Akihito; Hirano, Tatsuhiko; Tamai, Kazusei; Morinaga, Hitoshi

    2011-05-01

    The bald disappearance of barrier metal had been observed on the wafer after Cu chemical mechanical planarization (CMP) processing. It was speculated that this phenomenon occurs because the excessively oxidized Ta by electrochemical reaction with Cu ion was removed more easily than the normal Ta oxide around it. The inhibition of the electrochemical reaction is necessary to solve this phenomenon.

  14. 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.

  15. Mechanical and tribological properties of ion beam-processed surfaces

    SciTech Connect

    Kodali, P.

    1998-01-01

    The intent of this work was to broaden the applications of well-established surface modification techniques and to elucidate the various wear mechanisms that occur in sliding contact of ion-beam processed surfaces. The investigation included characterization and evaluation of coatings and modified surfaces synthesized by three surface engineering methods; namely, beam-line ion implantation, plasma-source ion implantation, and DC magnetron sputtering. Correlation among measured properties such as surface hardness, fracture toughness, and wear behavior was also examined. This dissertation focused on the following areas of research: (1) investigating the mechanical and tribological properties of mixed implantation of carbon and nitrogen into single crystal silicon by beam-line implantation; (2) characterizing the mechanical and tribological properties of diamond-like carbon (DLC) coatings processed by plasma source ion implantation; and (3) developing and evaluating metastable boron-carbon-nitrogen (BCN) compound coatings for mechanical and tribological properties. The surface hardness of a mixed carbon-nitrogen implant sample improved significantly compared to the unimplanted sample. However, the enhancement in the wear factor of this sample was found to be less significant than carbon-implanted samples. The presence of nitrogen might be responsible for the degraded wear behavior since nitrogen-implantation alone resulted in no improvement in the wear factor. DLC coatings have low friction, low wear factor, and high hardness. The fracture toughness of DLC coatings has been estimated for the first time. The wear mechanism in DLC coatings investigated with a ruby slider under a contact stress of 1 GPa was determined to be plastic deformation. The preliminary data on metastable BCN compound coatings indicated high friction, low wear factor, and high hardness.

  16. Plant uprooting by flow as a fatigue mechanical process

    NASA Astrophysics Data System (ADS)

    Perona, Paolo; Edmaier, Katharina; Crouzy, Benot

    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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  18. Nanoscale molecular traps

    NASA Astrophysics Data System (ADS)

    Chou, Chia-Fu; Wei, Qihuo; Gu, Jian; Zenhausern, Frederic; Swami, Nathan

    2006-03-01

    We have constructed nanoscale molecular traps using electrodeless, or insulator-based, dielectrophoresis [1, 2]. The molecular traps consist an array of nanoscale dielectric constrictions defined using electron-beam lithography on nanofluidic passages. The device was then sealed using an extremely simple room-temperature sealing process with virtually no pressure applied. Upon the application of an external ac electric field, the field will be focused at the constrictions and high field gradient can be generated to trap molecules dynamically in aqueous solutions. We demonstrated the trapping of small protein molecules in an array of these nanoscale molecular traps down to 50 nm in size. [1] C.F. Chou, J.O. Tegenfeldt, O. Bakajin, S.S. Chan, E.C. Cox, N. Darnton, T.A.J. Duke, R.H. Austin (2002). ``Electrodeless Dielectrophoresis of Single and Double Stranded DNA'', Biophys. J. 83, 2170-2179. [2] C.F. Chou, F. Zenhausern (2003). ``Electrodeless Dielectrophoresis for Micro Total Analysis Systems'', IEEE Eng. Med. Biol., Nov./Dec., 62-67.

  19. Switching Oxide Traps

    NASA Technical Reports Server (NTRS)

    Oldham, Timothy R.

    2003-01-01

    We consider radiation-induced charge trapping in SiO2 dielectric layers, primarily from the point of view of CMOS devices. However, SiO2 insulators are used in many other ways, and the same defects occur in other contexts. The key studies, which determined the nature of the oxide charge traps, were done primarily on gate oxides in CMOS devices, because that was the main radiation problem in CMOS at one time. There are two major reviews of radiation-induced oxide charge trapping already in the literature, which discuss the subject in far greater detail than is possible here. The first of these was by McLean et al. in 1989, and the second, ten years later, was intended as an update, because of additional, new work that had been reported. Basically, the picture that has emerged is that ionizing radiation creates electron-hole pairs in the oxide, and the electrons have much higher mobility than the holes. Therefore, the electrons are swept out of the oxide very rapidly by any field that is present, leaving behind any holes that escape the initial recombination process. These holes then undergo a polaron hopping transport toward the Si/SiO2 interface (under positive bias). Near the interface, some fraction of them fall into deep, relatively stable, long-lived hole traps. The nature and annealing behavior of these hole traps is the main focus of this paper.

  20. Thermoelectrically cooled water trap

    DOEpatents

    Micheels, Ronald H.

    2006-02-21

    A water trap system based on a thermoelectric cooling device is employed to remove a major fraction of the water from air samples, prior to analysis of these samples for chemical composition, by a variety of analytical techniques where water vapor interferes with the measurement process. These analytical techniques include infrared spectroscopy, mass spectrometry, ion mobility spectrometry and gas chromatography. The thermoelectric system for trapping water present in air samples can substantially improve detection sensitivity in these analytical techniques when it is necessary to measure trace analytes with concentrations in the ppm (parts per million) or ppb (parts per billion) partial pressure range. The thermoelectric trap design is compact and amenable to use in a portable gas monitoring instrumentation.

  1. X-ray Imaging and preliminary studies of the X-ray self-emission from an innovative plasma-trap based on the Bernstein waves heating mechanism

    NASA Astrophysics Data System (ADS)

    Caliri, C.; Romano, F. P.; Mascali, D.; Gammino, S.; Musumarra, A.; Castro, G.; Celona, L.; Neri, L.; Altana, C.

    2013-10-01

    Electron Cyclotron Resonance Ion Sources (ECRIS) are based on ECR heated plasmas emitting high fluxes of X-rays. Here we illustrate a pilot study of the X-ray emission from a compact plasma-trap in which an off-resonance microwave-plasma interaction has been attempted, highlighting a possible Bernstein-Waves based heating mechanism. EBWs-heating is obtained via the inner plasma EM-to-ES wave conversion and enables to reach densities much larger than the cut-off ones. At LNS-INFN, an innovative diagnostic technique based on the design of a Pinhole Camera (PHC) coupled to a CCD device for X-ray Imaging of the plasma (XRI) has been developed, in order to integrate X-ray traditional diagnostics (XRS). The complementary use of electrostatic probes measurements and X-ray diagnostics enabled us to gain knowledge about the high energy electrons density and temperature and about the spatial structure of the source. The combination of the experimental data with appropriate modeling of the plasma-source allowed to estimate the X-ray emission intensity in different energy domains (ranging from EUV up to Hard X-rays). The use of ECRIS as X-ray source for multidisciplinary applications, is now a concrete perspective due to the intense fluxes produced by the new plasma heating mechanism.

  2. Processing, texture and mechanical properties of sintered silicon carbide

    NASA Technical Reports Server (NTRS)

    Landfermann, H.; Hausner, H.

    1988-01-01

    With regard to its favorable properties, in particular those shown at high temperatures, silicon carbide is of great interest for applications related to the construction of engines and turbines. Thus, silicon carbide could replace heat-resisting alloys with the objective to achieve a further increase in operational temperature. The present investigation is concerned with approaches which can provide silicon carbide material with suitable properties for the intended applications, taking into account the relations between characteristics of the raw material, material composition, sinter conditions, and results of the sintering process. The effects of density and texture formation on the mechanical properties are studied. It is found that a dense material with a fine-grained microstructure provides optimal mechanical properties, while any deviation from this ideal condition can lead to a considerable deterioration with respect to the material properties.

  3. Cotranslational processing mechanisms: towards a dynamic 3D model.

    PubMed

    Giglione, Carmela; Fieulaine, Sonia; Meinnel, Thierry

    2009-08-01

    Recent major advances have been made in understanding how cotranslational events are achieved in the course of protein biosynthesis. Specifically, several studies have shed light into the dynamic process of how nascent chains emerging from the ribosome are supported by protein biogenesis factors to ensure both processing and folding mechanisms. To take into account the awareness that coordination is needed, a new 'concerted model' recently proposed simultaneous action of both processes on the ribosome. In the model, any emerging nascent chain is first encountered by the chaperone trigger factor (TF), which forms an open cradle underneath the ribosomal exit tunnel. This cradle serves as a passive router that channels the nascent chains to the first cotranslational event, the proteolysis event performed by the N-terminal methionine excision machinery. Although fascinating, this model clearly raises more questions than it answers. Does the data used to develop this model stand up to scrutiny and, if not, what are the alternative mechanisms that the data suggest? PMID:19647435

  4. Processing Mechanisms for Interstellar Ices: Connections to the Solar System

    NASA Technical Reports Server (NTRS)

    Pendleton, Y. J.; Cuzzi, Jeffrey N. (Technical Monitor)

    1995-01-01

    The organic component of the interstellar medium, which has revealed itself through the ubiquitous 3.4 micrometers hydrocarbon absorption feature, is widespread throughout the disk of our galaxy and has been attributed to dust grains residing in the diffuse interstellar medium. The absorption band positions near 3.4 micrometers are characteristic of C-H stretching vibrations in the -CH3 and -CH2- groups of saturated aliphatic hydrocarbons associated with perturbing chemical groups. The production of complex molecules is thought to occur within dense molecular clouds when ice-mantled grains are processed by various energetic mechanisms. Studies of the processing of interstellar ices and the subsequent production of organic residues have relevance to studies of ices in the solar system, because primitive, icy solar system bodies such as those in the Kuiper belt are likely reservoirs of organic material, either preserved from the interstellar medium or produced in situ. Connections between the interstellar medium and the early solar nebula have long been a source of interest. A comparison of the interstellar organics and the Murchison meteorite illustrates the importance of probing the interstellar connection to the solar system, because although the carbonaceous meteorites are undoubtedly highly processed, they do retain specific interstellar signatures (such as diamonds, SiC grains, graphite and enriched D/H). The organic component, while not proven interstellar, has a remarkable similarity to the interstellar organics observed in over a dozen sightlines through our galaxy. This paper compares spectra from laboratory organics produced through the processing of interstellar ice analog materials with the high resolution infrared observations of the interstellar medium in order to investigate the mechanisms (such as ion bombardment, plasma processing, and UV photolysis) that may be producing the organics in the ISM.

  5. Processing and mechanical characterization of nano twinned copper by electrodeposition

    NASA Astrophysics Data System (ADS)

    Sriram, Vinay

    Nanotwinned copper is being increasingly investigated due to their unique properties such as ultra-high yield strength, good ductility and electrical conductivity. These properties make nanotwinned copper an ideal candidate to be used in VLSI interconnects. Pulse electrodeposition experimental conditions for blanket films of nanotwinned copper on steel and silicon substrate have been investigated in the current dissertation. Preferred orientation has been found to be dependent on deposition conditions and has been studied by XRD. The mechanism of formation of twin boundaries has been investigated by carrying out in situ stress measurements during pulse electrodeposition. Results indicate that twin boundaries may be formed by stress relaxation during off time period of the pulse. Mechanical properties of the nanotwinned Cu films were measured by nanoindentation and in situ TEM nanocompression experiments. Nanoindentation results show that hardness, yield strength of nanotwinned Cu increased with decreasing twin spacing. A new technique has been utilized for the first time to visualize deformation mechanisms of nanotwinned, nanocrystalline and single crystal Cu. In situ compression experiments were carried out on Cu pillars of the same order of dimensions currently used in back end semiconductor technology. Deformation twinning in nanocrystalline Cu has been captured and the shear stress needed to form deformation twins has been measured. Deformation mechanism of nanotwinned Cu by process of absorption and transmission of dislocations has been visualized and is in accordance with MD simulations carried out. Shear stress measured for the absorption and transmission of dislocation in twin boundaries are in agreement with those from theoretical based calculations. Preliminary experiments carried out on single crystal Cu show that initial dislocation nucleation can happen more easily at low displacement rates in comparison with nanotwinned Cu. Strengthening mechanism of nanotwinned copper has been investigated in the current dissertation.

  6. Hadronization Mechanisms and Spin Effects in High Energy Fragmentation Processes

    NASA Astrophysics Data System (ADS)

    Liang, Zuo-Tang

    2002-03-01

    Spin effects in high energy fragmentation processes can provide us with important information on hadronization mechanisms and spin structure of hadrons. It can in particular give new tests to the hadronization models. In this talk, we make a brief introduction to the different topics studied in this connection and a short summary of the available data. After that, we present a short summary of the main theoretical results we obtained in studying these different topics. The talk was mainly based on the publications [4-8] which have been finished in collaboration with C.Boros, Liu Chun-xiu and Xu Qing-hua.

  7. Mechanisms of Carbon Nanotube Production by Laser Ablation Process

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.; Arepalli, Sivaram; Nikolaev, Pavel; Smalley, Richard E.; Nocholson, Leonard S. (Technical Monitor)

    2000-01-01

    We will present possible mechanisms for nanotube production by laser oven process. Spectral emission of excited species during laser ablation of a composite graphite target is compared with that of laser irradiated C60 vapor. The similarities in the transient and spectral data suggest that fullerenes are intermediate precursors for nanotube formation. The confinement of the ablation products by means of a 25-mm diameter tube placed upstream of the target seems to improve the production and purity of nanotubes. Repeated laser pulses vaporize the amorphous/graphitic carbon and possibly catalyst particles, and dissociate fullerenes yielding additional feedstock for SWNT growth.

  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. Ab initio quantum mechanical/molecular mechanical simulation of electron transfer process: Fractional electron approach

    SciTech Connect

    Zeng Xiancheng; Hu Hao; Hu Xiangqian; Cohen, Aron J.; Yang Weitao

    2008-03-28

    Electron transfer (ET) reactions are one of the most important processes in chemistry and biology. Because of the quantum nature of the processes and the complicated roles of the solvent, theoretical study of ET processes is challenging. To simulate ET processes at the electronic level, we have developed an efficient density functional theory (DFT) quantum mechanical (QM)/molecular mechanical (MM) approach that uses the fractional number of electrons as the order parameter to calculate the redox free energy of ET reactions in solution. We applied this method to study the ET reactions of the aqueous metal complexes Fe(H{sub 2}O){sub 6}{sup 2+/3+} and Ru(H{sub 2}O){sub 6}{sup 2+/3+}. The calculated oxidation potentials, 5.82 eV for Fe(II/III) and 5.14 eV for Ru(II/III), agree well with the experimental data, 5.50 and 4.96 eV, for iron and ruthenium, respectively. Furthermore, we have constructed the diabatic free energy surfaces from histogram analysis based on the molecular dynamics trajectories. The resulting reorganization energy and the diabatic activation energy also show good agreement with experimental data. Our calculations show that using the fractional number of electrons (FNE) as the order parameter in the thermodynamic integration process leads to efficient sampling and validate the ab initio QM/MM approach in the calculation of redox free energies.

  10. Innovative Application of Mechanical Activation for Rare Earth Elements Recovering: Process Optimization and Mechanism Exploration.

    PubMed

    Tan, Quanyin; Deng, Chao; Li, Jinhui

    2016-01-01

    With the rapidly expanding use of fluorescent lamps (FLs) and increasing interest in conservation and sustainable utilization of critical metals such as rare earth elements (REEs), the recovering of REEs from phosphors in waste FLs is becoming a critical environmental and economic issue. To effectively recycle REEs with metallurgical methods, mechanical activation by ball milling was introduced to pretreat the waste phosphors. This current study put the emphasis on the mechanical activation and leaching processes for REEs, and explored the feasibility of the method from both theoretical and practical standpoints. Results showed physicochemical changes of structural destruction and particle size reduction after mechanical activation, leading to the easy dissolution of REEs in the activated samples. Under optimal conditions, dissolution yields of 89.4%, 93.1% and 94.6% for Tb, Eu and Y, respectively, were achieved from activated waste phosphors using hydrochloric acid as the dissolution agent. The shrinking core model proved to be the most applicable for the leaching procedure, with an apparent activation energy of 10.96 ± 2.79 kJ/mol. This novel process indicates that mechanical activation is an efficient method for recovering REEs from waste phosphors, and it has promising potential for REE recovery with low cost and high efficiency. PMID:26819083

  11. Innovative Application of Mechanical Activation for Rare Earth Elements Recovering: Process Optimization and Mechanism Exploration

    PubMed Central

    Tan, Quanyin; Deng, Chao; Li, Jinhui

    2016-01-01

    With the rapidly expanding use of fluorescent lamps (FLs) and increasing interest in conservation and sustainable utilization of critical metals such as rare earth elements (REEs), the recovering of REEs from phosphors in waste FLs is becoming a critical environmental and economic issue. To effectively recycle REEs with metallurgical methods, mechanical activation by ball milling was introduced to pretreat the waste phosphors. This current study put the emphasis on the mechanical activation and leaching processes for REEs, and explored the feasibility of the method from both theoretical and practical standpoints. Results showed physicochemical changes of structural destruction and particle size reduction after mechanical activation, leading to the easy dissolution of REEs in the activated samples. Under optimal conditions, dissolution yields of 89.4%, 93.1% and 94.6% for Tb, Eu and Y, respectively, were achieved from activated waste phosphors using hydrochloric acid as the dissolution agent. The shrinking core model proved to be the most applicable for the leaching procedure, with an apparent activation energy of 10.96 ± 2.79 kJ/mol. This novel process indicates that mechanical activation is an efficient method for recovering REEs from waste phosphors, and it has promising potential for REE recovery with low cost and high efficiency. PMID:26819083

  12. Innovative Application of Mechanical Activation for Rare Earth Elements Recovering: Process Optimization and Mechanism Exploration

    NASA Astrophysics Data System (ADS)

    Tan, Quanyin; Deng, Chao; Li, Jinhui

    2016-01-01

    With the rapidly expanding use of fluorescent lamps (FLs) and increasing interest in conservation and sustainable utilization of critical metals such as rare earth elements (REEs), the recovering of REEs from phosphors in waste FLs is becoming a critical environmental and economic issue. To effectively recycle REEs with metallurgical methods, mechanical activation by ball milling was introduced to pretreat the waste phosphors. This current study put the emphasis on the mechanical activation and leaching processes for REEs, and explored the feasibility of the method from both theoretical and practical standpoints. Results showed physicochemical changes of structural destruction and particle size reduction after mechanical activation, leading to the easy dissolution of REEs in the activated samples. Under optimal conditions, dissolution yields of 89.4%, 93.1% and 94.6% for Tb, Eu and Y, respectively, were achieved from activated waste phosphors using hydrochloric acid as the dissolution agent. The shrinking core model proved to be the most applicable for the leaching procedure, with an apparent activation energy of 10.96 ± 2.79 kJ/mol. This novel process indicates that mechanical activation is an efficient method for recovering REEs from waste phosphors, and it has promising potential for REE recovery with low cost and high efficiency.

  13. A facile access to polyfunctional oxygen-containing heterocycles via intramolecularly formed protic oxonium ylide trapping processes.

    PubMed

    Guo, Xin; Liu, Wei; Hu, Wenhao

    2014-01-01

    Based on the assumption that intramolecularly formed protic oxonium ylides could be trapped by electrophiles, transition-metal-catalyzed reactions of diazoesters bearing a primary hydroxy group with electron-deficient aldehydes and isatins were examined. Good to high chemo- and diastereoselectivities were achieved with reactions catalyzed by Cu(hfacac)2. The reactions were assumed to occur via tandem intramolecular protic oxonium ylide formation and subsequent aldol-type addition. They not only provided an efficient entry to 3-substituted 1,4-dioxan-2-one heterocycles with at least one quaternary carbon center but also provided experimental evidence for a stepwise pathway for the transition-metal-catalyzed intramolecular O-H insertion of diazo compounds. PMID:24203678

  14. How does a magnetic trap work?

    NASA Astrophysics Data System (ADS)

    Pérez-Ríos, J.; Sanz, A. S.

    2013-11-01

    Magnetic trapping is a cornerstone of modern ultracold physics and its applications, including quantum information processing, quantum metrology, quantum optics, and high-resolution spectroscopy. Here, a comprehensive analysis and discussion of the basic physics behind the most commonly used magnetic traps used in Bose-Einstein condensation is presented. This analysis includes the quadrupole trap, the time-averaged orbiting potential trap, and the Ioffe-Pritchard trap. The trapping conditions and efficiency of these devices can be determined from simple derivations based on classical electromagnetism, even though they operate on quantum objects.

  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; Jrgensen, 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. VACUUM TRAP

    DOEpatents

    Gordon, H.S.

    1959-09-15

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

  17. 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."

  18. Hyporheic flow and transport processes: Mechanisms, models, and biogeochemical implications

    NASA Astrophysics Data System (ADS)

    Boano, F.; Harvey, J. W.; Marion, A.; Packman, A. I.; Revelli, R.; Ridolfi, L.; Wrman, A.

    2014-12-01

    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.

  19. 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.

  20. Ion traps fabricated in a CMOS foundry

    SciTech Connect

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

    2014-07-28

    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.

  1. Processing, mechanical properties and microfractography of polymer concrete composite material

    SciTech Connect

    Kim, K.

    1986-01-01

    Mechanical properties of methyl methacrylate (MMA)-based polymer concrete (PC) were studied by means of various mechanical tests and microscopic observation. It was found that the casting and curing process is one of the most important factors influencing the strength of PC. Since the compressive strength of PC gives a general indication of its overall quality, and since PC materials are likely to be utilized mainly as compressive members, performance and evaluation of compression tests were emphasized. It was found that the compressive strength is directly proportional to the logarithm of loading rate. The compressive strength increased rapidly with curing time, The compressive strength increased with decreasing H/D (height/diameter) ratio of the specimen. The compressive strength of MMA based PC increased linearly with increasing hardness (Rockwell-K scale, R/sub K/). This linear correlation was found to be independent of the casting process and curing time. Tension-tension fluctuating fatigue tests were performed to determine the behavior of PC under repeated loading. In fatigue tests with a maximum tension less than 50% of the ultimate tensile strength, failure did not occur even after 10/sup 7/ cycles. The cracking pattern of PC is noticeably different from that of regular portland cement concrete.

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

    SciTech Connect

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

    2010-11-11

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

  3. 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.

  4. 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.

  5. Trapped particle absorption by the ring of Jupiter

    SciTech Connect

    Fillius, W.

    1985-08-01

    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.

  6. Brain mechanisms associated with top-down processes in perception.

    PubMed Central

    Frith, C; Dolan, R J

    1997-01-01

    Perception arises through an interaction between sensory input and prior knowledge. We propose that at least two brain areas are required for such an interaction: the 'site' where analysis of afferent signals occurs and the 'source' which applies the relevant prior knowledge. In the human brain, functional imaging studies have demonstrated that selective attention modifies activity in early visual processing areas specific to the attended feature. Early processing areas are also modified when prior knowledge permits a percept to emerge from an otherwise meaningless stimulus. Sources of this modification have been identified in parietal cortex and in prefrontal cortex. Modification of early processing areas also occurs on the basis of prior knowledge about the predicted sensory effects of the subject's own actions. Activity associated with mental imagery resembles that associated with response preparation (for motor imagery) and selective attention (for sensory imagery) suggesting that mental imagery reflects the effects of prior knowledge on sensory processing areas in the absence of sensory input. Damage to sensory processing areas can lead to a form of sensory hallucination which seems to arise from the interaction of prior knowledge with random sensory activity. In contrast, hallucinations associated with schizophrenia may arise from a failure of prior knowledge about motor intentions to modify activity in relevant sensory areas. When functioning normally, this mechanism permits us to distinguish our own actions from those of independent agents in the outside world. Failure to make this distinction correctly may account for the strong association between hallucinations and paranoid delusions in schizophrenia; the patient not only hears voices, but attributes (usually hostile) intentions to these voices. PMID:9304688

  7. Mechanisms for Reduced Excess Sludge Production in the Cannibal Process.

    PubMed

    Labelle, Marc-André; Dold, Peter L; Comeau, Yves

    2015-08-01

    Reducing excess sludge production is increasingly attractive as a result of rising costs and constraints with respect to sludge treatment and disposal. A technology in which the mechanisms remain not well understood is the Cannibal process, for which very low sludge yields have been reported. The objective of this work was to use modeling as a means to characterize excess sludge production at a full-scale Cannibal facility by providing a long sludge retention time and removing trash and grit by physical processes. The facility was characterized by using its historical data, from discussion with the staff and by conducting a sampling campaign to prepare a solids inventory and an overall mass balance. At the evaluated sludge retention time of 400 days, the sum of the daily loss of suspended solids to the effluent and of the waste activated sludge solids contributed approximately equally to the sum of solids that are wasted daily as trash and grit from the solids separation module. The overall sludge production was estimated to be 0.14 g total suspended solids produced/g chemical oxygen demand removed. The essential functions of the Cannibal process for the reduction of sludge production appear to be to remove trash and grit from the sludge by physical processes of microscreening and hydrocycloning, respectively, and to provide a long sludge retention time, which allows the slow degradation of the "unbiodegradable" influent particulate organics (XU,Inf) and the endogenous residue (XE). The high energy demand of 1.6 kWh/m³ of treated wastewater at the studied facility limits the niche of the Cannibal process to small- to medium-sized facilities in which sludge disposal costs are high but electricity costs are low. PMID:26237684

  8. Study of formation of deep trapping mechanism by UV, beta and gamma irradiated Eu(3+) activated SrY2O4 and Y4Al2O9 phosphors.

    PubMed

    Dubey, Vikas; Kaur, Jagjeet; Parganiha, Yogita; Suryanarayana, N S; Murthy, K V R

    2016-04-01

    This paper reports the thermoluminescence properties of Eu(3+) doped different host matrix phosphors (SrY2O4 and Y4Al2O9). The phosphor is prepared by high temperature solid state reaction method. The method is suitable for large scale production and fixed concentration of boric acid using as a flux. The prepared samples were characterized by X-ray diffraction technique and the crystallite size calculated by Scherer's formula. The prepared phosphor characterized by Scanning Electron Microscopic (SEM), Fourier Transform Infrared (FTIR), Energy Dispersive X-ray analysis (EDX), thermoluminescence (TL) and Transmission Electron Microscopic (TEM) techniques. The prepared phosphors for different concentration of Eu(3+) ions were examined by TL glow curve for UV, beta and gamma irradiation. The UV 254nm source used for UV irradiation, Sr(90) source was used for beta irradiation and Co(60) source used for gamma irradiation. SrY2O4:Eu(3+)and Y4Al2O9:Eu(3+) phosphors which shows both higher temperature peaks and lower temperature peaks for UV, beta and gamma irradiation. Here UV irradiated sample shows the formation of shallow trap (surface trapping) and the gamma irradiated sample shows the formation of deep trapping. The estimation of trap formation was evaluated by knowledge of trapping parameters. The trapping parameters such as activation energy, order of kinetics and frequency factor were calculated by peak shape method. Here most of the peak shows second order of kinetics. The effect of gamma, beta and UV exposure on TL studies was also examined and it shows linear response with dose which indicate that the samples may be useful for TL dosimetry. Formation of deep trapping mechanism by UV, beta and gamma irradiated Eu(3+) activated SrY2O4 and Y4Al2O9 phosphors is discussed in this paper. PMID:26748019

  9. Fault structure, wear mechanisms and rupture processes in pseudotachylyte generation

    NASA Astrophysics Data System (ADS)

    Swanson, Mark T.

    1992-04-01

    Fault-generated pseudotachylyte is found within both cataclastic and mylonitic host rocks suggesting that rapid catastrophic displacements have occurred at a variety of depths within paleoseismogenic zones. Pseudotachylyte-bearing fault zones represent a composite of structural features associated with the process of earthquake rupture propagation and coseismic slip. The development of multiple pseudotachylyte veins in fault linkages, duplexes, sidewall ripouts, en echelon arrays and brittle zones suggests repeated rupturing during a series of characteristic earthquakes. Each earthquake, as a coseismic slip event, can be subdivided into initial rupture, acceleration, stable sliding and final deceleration stages. These evolve through distinctive sequences of wear and deformation mechanisms that vary with sliding velocity, duration of slip, total displacement and the hydrodynamics of the developing fault zone. Slip is thought to proceed toward surface refinement and possible frictional melting following the propagation of leading shear fracture process zones. The passage of the initial process zone of oblique fracturing would be followed by linkage to a throughgoing structure with asperity reduction through brecciation, comminution and refined cataclastic flow for frictional melting in an abrasive wear-dominant model. At greater depths in the presence of mylonitic anisotropy, slip would proceed through initial layer-parallel surfaces and duplex linkages with rapid surface refinement through plastic smearing and laminar flow for frictional melting in an adhesive wear-dominant model.

  10. Review. Neurobiological mechanisms for opponent motivational processes in addiction.

    PubMed

    Koob, George F; Le Moal, Michel

    2008-10-12

    The conceptualization of drug addiction as a compulsive disorder with excessive drug intake and loss of control over intake requires motivational mechanisms. Opponent process as a motivational theory for the negative reinforcement of drug dependence has long required a neurobiological explanation. Key neurochemical elements involved in reward and stress within basal forebrain structures involving the ventral striatum and extended amygdala are hypothesized to be dysregulated in addiction to convey the opponent motivational processes that drive dependence. Specific neurochemical elements in these structures include not only decreases in reward neurotransmission such as dopamine and opioid peptides in the ventral striatum, but also recruitment of brain stress systems such as corticotropin-releasing factor (CRF), noradrenaline and dynorphin in the extended amygdala. Acute withdrawal from all major drugs of abuse produces increases in reward thresholds, anxiety-like responses and extracellular levels of CRF in the central nucleus of the amygdala. CRF receptor antagonists block excessive drug intake produced by dependence. A brain stress response system is hypothesized to be activated by acute excessive drug intake, to be sensitized during repeated withdrawal, to persist into protracted abstinence and to contribute to stress-induced relapse. The combination of loss of reward function and recruitment of brain stress systems provides a powerful neurochemical basis for the long hypothesized opponent motivational processes responsible for the negative reinforcement driving addiction. PMID:18653439

  11. Reconstruction of mechanically recorded sound by image processing

    NASA Astrophysics Data System (ADS)

    Fedeyev, Vitaliy; Haber, Carl; Radding, Zachary; Maul, Christian; McBride, John; Golden, Mitchell

    2001-05-01

    Audio information stored in the undulations of grooves in a medium such as a phonograph record or cylinder may be reconstructed, without contact, by measuring the groove shape using precision optical metrology methods and digital image processing. In this approach, audio signal processing is accomplished by two- or three-dimensional image analysis and processing. The viability of these methods was recently demonstrated on a 78 rpm shellac disc using two-dimensional image acquisition and analysis methods [V. Fadeyev and C. Haber, J. Audio Eng. Soc. 51(12), 1172-1185 (2003)]. The present work expands on these results. A three-dimensional reconstruction of mechanically recorded sound is reported. The source material, an Edison cylinder, was scanned using confocal microscopy and resulted in a faithful playback of the recorded information. Methods to accelerate the scan rates and make these techniques practical for use in working archives are reported as well. [Work supported by the Laboratory Technology Research Program (SC-32), within the Office of Science, U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

  12. Multi-spacecraft Observations of Heavy Ion Dropouts: Physical Processes, Fractionation Rates, and Release Mechanisms

    NASA Astrophysics Data System (ADS)

    Weberg, M. J.; Lepri, S. T.; Zurbuchen, T.

    2014-12-01

    Heavy ion dropouts in the solar wind are thought to originate from large, closed coronal loops. The distinctive, mass-dependent fractionation patterns of the dropouts requires that their source loops are relatively quiet and stable long enough (on the order of a day) to undergo gravitational settling. Therefore by studying the composition of heavy ion dropouts we are able to peer into the solar corona and glean information about the fine balance of physical processes. Additionally, the occurrence rates and magnetic profiles of dropouts suggest specific forms of magnetic reconnection are responsible for the release of the otherwise trapped plasma into the solar wind. In this study we identify and compare dropouts observed by two different satellites, ACE and Ulysses, which together provide over 20 years of continuous observations at a variety of heliographic latitudes and radii. The resulting partial global view (or 3D view) enables us to identify coronal source regions and release mechanisms of heavy ion dropouts. We also discuss a physical model of gravitational settling which can be used to reconcile fractionation rates with the rate at which plasma must be escaping via reconnection. Our conclusions and results may contribute towards the ongoing refinement and validation of theories which predict the origin of "slow type" solar wind.

  13. Penning trap mass measurements of {sup 99-109}Cd with the ISOLTRAP mass spectrometer, and implications for the rp process

    SciTech Connect

    Breitenfeldt, M.; Schweikhard, L.; Audi, G.; Lunney, D.; Naimi, S.; Beck, D.; Herfurth, F.; Blaum, K.; George, S.; Herlert, A.; Kowalska, M.; Kellerbauer, A.; Kluge, H.-J.; Neidherr, D.; Schatz, H.; Schwarz, S.

    2009-09-15

    Penning trap mass measurements of neutron-deficient Cd isotopes {sup 99-109}Cd have been performed with the ISOLTRAP mass spectrometer at ISOLDE/CERN, all with relative mass uncertainties below 3{center_dot}10{sup -8}. A new mass evaluation has been performed. The mass of {sup 99}Cd has been determined for the first time, which extends the region of accurately known mass values toward the doubly magic nucleus {sup 100}Sn. The implication of the results on the reaction path of the rp process in stellar x-ray bursts is discussed. In particular, the uncertainty of the abundance and the overproduction created by the rp-process for the mass A=99 are demonstrated by reducing the uncertainty of the proton-separation energy of {sup 100}InS{sub p}({sup 100}In) by a factor of 2.5.

  14. A Trapped Covalent Intermediate of a Glycoside Hydrolase on the Pathway to Transglycosylation. Insights from Experiments and Quantum Mechanics/Molecular Mechanics Simulations.

    PubMed

    Raich, Lluís; Borodkin, Vladimir; Fang, Wenxia; Castro-López, Jorge; van Aalten, Daan M F; Hurtado-Guerrero, Ramón; Rovira, Carme

    2016-03-16

    The conversion of glycoside hydrolases (GHs) into transglycosylases (TGs), i.e., from enzymes that hydrolyze carbohydrates to enzymes that synthesize them, represents a promising solution for the large-scale synthesis of complex carbohydrates for biotechnological purposes. However, the lack of knowledge about the molecular details of transglycosylation hampers the rational design of TGs. Here we present the first crystallographic structure of a natural glycosyl-enzyme intermediate (GEI) of Saccharomyces cerevisiae Gas2 in complex with an acceptor substrate and demonstrate, by means of quantum mechanics/molecular mechanics metadynamics simulations, that it is tuned for transglycosylation (ΔG(⧧) = 12 kcal/mol). The 2-OH···nucleophile interaction is found to be essential for catalysis: its removal raises the free energy barrier significantly (11 and 16 kcal/mol for glycosylation and transglycosylation, respectively) and alters the conformational itinerary of the substrate (from (4)C1 → [(4)E](⧧) → (1,4)B/(4)E to (4)C1 → [(4)H3](⧧) → (4)C1). Our results suggest that changes in the interactions involving the 2-position could have an impact on the transglycosylation activity of several GHs. PMID:26859322

  15. 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.; Ct, 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.

  16. Thermo-mechanical process for treatment of welds

    SciTech Connect

    Malik, R K

    1980-03-01

    Benefits from thermo-mechanical processing (TMP) of austenitic stainless steel weldments, analogous to hot isostatic pressing (HIP) of castings, most likely result from compressive plastic deformation, enhanced diffusion, and/or increased dislocation density. TMP improves ultrasonic inspectability of austenitic stainless steel welds owing to: conversion of cast dendrites into equiaxed austenitic grains, reduction in size and number of stringers and inclusions, and reduction of delta ferrite content. TMP induces structural homogenization and healing of void-type defects and thus contributes to an increase in elongation, impact strength, and fracture toughness as well as a significant reduction in data scatter for these properties. An optimum temperature for TMP or HIP of welds is one which causes negligible grain growth and an acceptable reduction in yield strength, and permits healing of porosity.

  17. Probabilistic structural mechanics research for parallel processing computers

    NASA Technical Reports Server (NTRS)

    Sues, Robert H.; Chen, Heh-Chyun; Twisdale, Lawrence A.; Martin, William R.

    1991-01-01

    Aerospace structures and spacecraft are a complex assemblage of structural components that are subjected to a variety of complex, cyclic, and transient loading conditions. Significant modeling uncertainties are present in these structures, in addition to the inherent randomness of material properties and loads. To properly account for these uncertainties in evaluating and assessing the reliability of these components and structures, probabilistic structural mechanics (PSM) procedures must be used. Much research has focused on basic theory development and the development of approximate analytic solution methods in random vibrations and structural reliability. Practical application of PSM methods was hampered by their computationally intense nature. Solution of PSM problems requires repeated analyses of structures that are often large, and exhibit nonlinear and/or dynamic response behavior. These methods are all inherently parallel and ideally suited to implementation on parallel processing computers. New hardware architectures and innovative control software and solution methodologies are needed to make solution of large scale PSM problems practical.

  18. 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.

  19. Processing and mechanical properties of HA/UHMWPE nanocomposites.

    PubMed

    Fang, Liming; Leng, Yang; Gao, Ping

    2006-07-01

    A hydroxyapatite (HA) particulate reinforced ultrahigh molecular weight polyethylene (UHMWPE) nanocomposite was fabricated by compounding HA and UHMWPE mixtures in paraffin oil using twin-screw extrusion and then compression molding. Scanning electron microscope images revealed that HA aggregates were broken down to nano-sized particles and homogeneously dispersed in UHMWPE by the combined processes of twin-screw extrusion and UHMWPE swelling treatment. Transmission electron microscope images indicated the HA particles and UHMWPE matrix were intimately contacted through mechanical interlocking. The composite with the HA volume fraction of 0.23 exhibited a Young's modulus nine times higher than that of UHMWPE, while the composite maintained the excellent toughness feature of UHMWPE. The fracture strain reached over 300%, significantly higher than other types of biocomposites. PMID:16564570

  20. 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.

    2015-08-01

    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.

  1. Medial Efferent Mechanisms in Children with Auditory Processing Disorders

    PubMed Central

    Mishra, Srikanta K.

    2014-01-01

    Auditory processing disorder (APD) affects about 25% 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

  2. Steam trap monitor

    DOEpatents

    Ryan, Michael J. (Plainfield, IL)

    1988-01-01

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

  3. A mechanism for the hydrogen uptake process in zirconium alloys

    NASA Astrophysics Data System (ADS)

    Cox, B.

    1999-01-01

    Hydrogen uptake data for thin Zircaloy-2 specimens in steam at 300-400C have been analysed to show that there is a decrease in the rate of uptake with respect to the rate of oxidation when the terminal solid solubility (TSS) of hydrogen in the metal is exceeded. In order for TSS to be reached during pre-transition oxidation a very thin 0.125 mm Zircaloy sheet was used. The specimens had been pickled initially removing all Zr 2(Fe/Ni) particles from the initial surfaces, yet the initial hydrogen uptake rates were still much higher than for Zircaloy-4 or a binary Zr/Fe alloy that did not contain phases that dissolve readily during pickling. Cathodic polarisation at room temperature in CuSO 4 solution showed that small cracks or pores formed the cathodic sites in pre-transition oxide films. Some were at pits resulting from the initial dissolution of the Zr 2(Fe/Ni) phase; others were not; none were at the remaining intermetallics in the original surface. These small cracks are thought to provide the ingress routes for hydrogen. A microscopic steam starvation process at the bottoms of these small cracks or pores, leading to the accumulation of hydrogen adjacent to the oxide/metal interface, and causing breakdown of the passive oxide forming at the bottom of the flaw, is thought to provide the mechanism for the hydrogen uptake process during both pre-transition and post-transition oxidation.

  4. Statistical mechanical studies on the information processing with quantum fluctuation

    NASA Astrophysics Data System (ADS)

    Otsubo, Yosuke; Inoue, Jun-Ichi; Nagata, Kenji; Okada, Masato

    2014-03-01

    Quantum fluctuation induces the tunneling between states in a system and then can be used in combinatorial optimization problems. Such an algorithm is called quantum adiabatic computing. In this work, we investigate the quality of an information processing based on Bayes inference with the quantum fluctuation through the statistical mechanical approach. We then focus on the error correcting codes and CDMA multiuser demodulation which are described by conventional solvable spin glass models and can be analyzed by replica method in the thermodynamic limit. Introducing the quantum fluctuation into the decoding process of each problem, which is called quantum maximizer of the posteriori probability (QMPM) estimate, we analyze the decoding quality and then compare the results with those by the conventional MPM estimate which corresponds to finite temperature decoding From our limited results, the MPM based on the quantum fluctuation seems to achieve the same decoding quality as the thermal MPM does. We clarify the relationship between the optimal amplitude of transverse field and temperature for the mixture of quantum and classical MPMs. This work is supported by JSPS KAKENHI Grant Numbers 12J06501, 25330283, 25120009.

  5. Traps for capturing insects.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Abstract Traps developed for capturing insects are as varied as the purpose for the trapping, the insects targeted, and the habitats in which they are used. An overview of the basic trap types and variations of those basic trap types for specific uses is presented. Traps may be used with or withou...

  6. Batch-processed GdBCO-Ag bulk superconductors fabricated using generic seeds with high trapped fields

    NASA Astrophysics Data System (ADS)

    Shi, Y.; Hari Babu, N.; Iida, K.; Yeoh, W. K.; Dennis, A. R.; Pathak, S. K.; Cardwell, D. A.

    2010-09-01

    Large, single grains of Y-Ba-Cu-O (YBCO) have been batch-processed to date by the top seeded melt growth (TSMG) process using NdBCO or SmBCO seed crystals. It has proved difficult, however, to economically batch-process light rare earth (LRE) LRE-Ba-Cu-O bulk high temperature superconductors, which have higher critical current densities and irreversibility fields than YBCO, and therefore greater potential for high field engineering applications. In this paper, we report a novel batch-process based on a cheap, readily available generic seed crystal, developed recently at Cambridge, and a TSMG melt processing technique based on cold seeding in air for the batch fabrication of Gd-Ba-Cu-O-Ag single grains. The superconducting properties of the (LRE)BCO single grains fabricated by this process are, in all respects, equivalent to those processed more conventionally in a reduced oxygen atmosphere.

  7. Melt processing and mechanical properties of polyolefin block copolymers

    NASA Astrophysics Data System (ADS)

    Phatak, Alhad

    This thesis addresses the mechanical properties and melt processing behavior of lamellae-forming polyolefin based block copolymers composed of poly(cyclohexylethylene) (C) and polyethylene (E). These materials display a variety of desirable physical properties, most notably, a significantly higher upper use temperature than polystyrene based block copolymers used in traditional thermoplastic elastomers and plastics. A comprehensive framework was developed to describe the toughness of C/E block copolymers having a wide range of chain architectures. Uniaxial tensile testing experiments revealed that the weight fraction of E chains confined between C domains (psiE) critically controls the elongation-to-break. A design parameter was thus identified to potentially predict the toughness of any hard-soft block copolymer system. CEC and CECEC block copolymers, and their blends were extruded through a capillary rheometer, and the resulting lamellar alignment was studied. Extrudates were found to possess mixed or perpendicular alignment of lamellae, in agreement with the previously established phenomenology from oscillatory shear experiments. CEC and CECEC extrudates displayed dramatically different surface properties. CECEC extrudates exhibited undesirable surface roughness, which was eliminated by adding just 20% CEC. Thus, an "optimum" CEC/CECEC blend composition window was identified that provides high toughness, without undesirable surface instabilities during extrusion. In the final part of the thesis, an experimental apparatus was designed and built to produce melt blown fibers on a laboratory scale. A number of polymers, including a CEC triblock, were extruded using a capillary rheometer and hot air streams were used to successfully attenuate the extrudate into sub-micron fibers. These results prove the potential of the melt blowing process to compete with electrospinning, which is currently the only continuous process to produce polymeric nanofibers.

  8. Quantum Mechanics/Molecular Mechanics Modeling of Enzymatic Processes: Caveats and Breakthroughs.

    PubMed

    Quesne, Matthew G; Borowski, Tomasz; de Visser, Sam P

    2016-02-01

    Nature has developed large groups of enzymatic catalysts with the aim to transfer substrates into useful products, which enables biosystems to perform all their natural functions. As such, all biochemical processes in our body (we drink, we eat, we breath, we sleep, etc.) are governed by enzymes. One of the problems associated with research on biocatalysts is that they react so fast that details of their reaction mechanisms cannot be obtained with experimental work. In recent years, major advances in computational hardware and software have been made and now large (bio)chemical systems can be studied using accurate computational techniques. One such technique is the quantum mechanics/molecular mechanics (QM/MM) technique, which has gained major momentum in recent years. Unfortunately, it is not a black-box method that is easily applied, but requires careful set-up procedures. In this work we give an overview on the technical difficulties and caveats of QM/MM and discuss work-protocols developed in our groups for running successful QM/MM calculations. PMID:26696271

  9. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Alaskan mechanized salmon processing subcategory. 408.170 Section 408.170 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory 408.170 Applicability; description of the Alaskan mechanized salmon processing subcategory. The provisions of this subpart...

  10. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Coast mechanized salmon processing subcategory. 408.190 Section 408.190 Protection of Environment... PROCESSING POINT SOURCE CATEGORY West Coast Mechanized Salmon Processing Subcategory 408.190 Applicability; description of the West Coast mechanized salmon processing subcategory. The provisions of this subpart...

  11. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Alaskan mechanized salmon processing subcategory. 408.170 Section 408.170 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory 408.170 Applicability; description of the Alaskan mechanized salmon processing subcategory. The provisions of this subpart...

  12. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Coast mechanized salmon processing subcategory. 408.190 Section 408.190 Protection of Environment... PROCESSING POINT SOURCE CATEGORY West Coast Mechanized Salmon Processing Subcategory 408.190 Applicability; description of the West Coast mechanized salmon processing subcategory. The provisions of this subpart...

  13. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Alaskan mechanized salmon processing subcategory. 408.170 Section 408.170 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory 408.170 Applicability; description of the Alaskan mechanized salmon processing subcategory. The provisions of this subpart...

  14. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Coast mechanized salmon processing subcategory. 408.190 Section 408.190 Protection of Environment... PROCESSING POINT SOURCE CATEGORY West Coast Mechanized Salmon Processing Subcategory 408.190 Applicability; description of the West Coast mechanized salmon processing subcategory. The provisions of this subpart...

  15. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Alaskan mechanized salmon processing subcategory. 408.170 Section 408.170 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory 408.170 Applicability; description of the Alaskan mechanized salmon processing subcategory. The provisions of this subpart...

  16. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Coast mechanized salmon processing subcategory. 408.190 Section 408.190 Protection of Environment... PROCESSING POINT SOURCE CATEGORY West Coast Mechanized Salmon Processing Subcategory 408.190 Applicability; description of the West Coast mechanized salmon processing subcategory. The provisions of this subpart...

  17. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Alaskan mechanized salmon processing subcategory. 408.170 Section 408.170 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Alaskan Mechanized Salmon Processing Subcategory 408.170 Applicability; description of the Alaskan mechanized salmon processing subcategory. The provisions of this subpart...

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Coast mechanized salmon processing subcategory. 408.190 Section 408.190 Protection of Environment... PROCESSING POINT SOURCE CATEGORY West Coast Mechanized Salmon Processing Subcategory 408.190 Applicability; description of the West Coast mechanized salmon processing subcategory. The provisions of this subpart...

  19. The dose-dependent tumor targeting of antibody-IFN? fusion proteins reveals an unexpected receptor-trapping mechanism in vivo.

    PubMed

    Hemmerle, Teresa; Neri, Dario

    2014-06-01

    Cytokines often display substantial toxicities at low concentrations, preventing their escalation for therapeutic treatment of cancer. Fusion proteins comprising cytokines and recombinant antibodies may improve the anticancer activity of proinflammatory cytokines. Murine IFN? was appended in the diabody format at the C-terminus of the F8 antibody, generating the F8-IFN? fusion protein. The F8 antibody is specific for the extra-domain A (EDA) of fibronectin, a tumor-associated antigen that is expressed in the vasculature and stroma of almost all tumor types. Tumor-targeting properties were measured in vivo using a radioiodinated preparation of the fusion protein. Therapy experiments were performed in three syngeneic murine models of cancer [F9 teratocarcinoma, WEHI-164 fibrosarcoma, and Lewis lung carcinoma (LLC)]. F8-IFN? retained the biologic activity of both the antibody and the cytokine moiety in vitro, but, unlike the parental F8 antibody, it did not preferentially localize to the tumors in vivo. However, when unlabeled F8-IFN? was administered before radioiodinated F8-IFN?, a selective accumulation at the tumor site was observed. F8-IFN? showed dose-dependent anticancer activity with a clear superiority over untargeted recombinant IFN?. The anticancer activity was potentiated by combining with F8-IL4 without additional toxicities, whereas combination of F8-IFN? with F8-TNF was lethal in all mice. Unlike other antibody-cytokine fusions, the use of IFN? as payload for anticancer therapy is associated with a receptor-trapping mechanism, which can be overcome by the administration of a sufficiently large amount of the fusion protein without any detectable toxicity at the doses used. PMID:24795141

  20. Ion traps as chemical sensors

    SciTech Connect

    Hart, K.J.

    1995-12-31

    Direct Sampling ion trap mass spectrometers (DSITMS) have been developed or are in the process of being developed for monitoring of chemical components from a large number of sources including ground water wells, incinerator stacks, fugitive process emissions, automobile exhaust, explosives, chemical agents and illicit drugs. With sufficient hardware and software support, automation of all aspects of sampling and ion trap operation is feasible. Thus, there is considerable potential for delivering a chemical sensor for a large range of organic compounds using ion trap mass spectrometers. Sensors are defined as a transducer with appropriate signal conditioning, computation and data transmission services. Chemical sensors, of course, utilize transducers capable of measuring concentrations of chemical compounds. The author discusses advances in the use of ion traps as chemical sensors.

  1. Additive manufacturing of Inconel 718 using electron beam melting: Processing, post-processing, & mechanical properties

    NASA Astrophysics Data System (ADS)

    Sames, William James, V.

    Additive Manufacturing (AM) process parameters were studied for production of the high temperature alloy Inconel 718 using Electron Beam Melting (EBM) to better understand the relationship between processing, microstructure, and mechanical properties. Processing parameters were analyzed for impact on process time, process temperature, and the amount of applied energy. The applied electron beam energy was shown to be integral to the formation of swelling defects. Standard features in the microstructure were identified, including previously unidentified solidification features such as shrinkage porosity and non-equilibrium phases. The as-solidified structure does not persist in the bulk of EBM parts due to a high process hold temperature (˜1000°C), which causes in situ homogenization. The most significant variability in as-fabricated microstructure is the formation of intragranular delta-phase needles, which can form in samples produced with lower process temperatures (< 960°C). A novel approach was developed and demonstrated for controlling the temperature of cool down, thus providing a technique for in situ heat treatment of material. This technique was used to produce material with hardness of 478+/-7 HV with no post-processing, which exceeds the hardness of peak-aged Inconel 718. Traditional post-processing methods of hot isostatic pressing (HIP) and solution treatment and aging (STA) were found to result in variability in grain growth and phase solution. Recrystallization and grain structure are identified as possible mechanisms to promote grain growth. These results led to the conclusion that the first step in thermal post-processing of EBM Inconel 718 should be an optimized solution treatment to reset phase variation in the as-fabricated microstructure without incurring significant grain growth. Such an optimized solution treatment was developed (1120°C, 2hr) for application prior to aging or HIP. The majority of as-fabricated tensile properties met ASTM AM Inconel 718 standards for yield stress and ultimate tensile strength, and STA yield stress, ultimate tensile strength, and elongation exceeded the ASTM standards for AM Inconel 718.

  2. Neural Mechanisms and Information Processing in Recognition Systems

    PubMed Central

    Ozaki, Mamiko; Hefetz, Abraham

    2014-01-01

    Nestmate recognition is a hallmark of social insects. It is based on the match/mismatch of an identity signal carried by members of the society with that of the perceiving individual. While the behavioral response, amicable or aggressive, is very clear, the neural systems underlying recognition are not fully understood. Here we contrast two alternative hypotheses for the neural mechanisms that are responsible for the perception and information processing in recognition. We focus on recognition via chemical signals, as the common modality in social insects. The first, classical, hypothesis states that upon perception of recognition cues by the sensory system the information is passed as is to the antennal lobes and to higher brain centers where the information is deciphered and compared to a neural template. Match or mismatch information is then transferred to some behavior-generating centers where the appropriate response is elicited. An alternative hypothesis, that of “pre-filter mechanism”, posits that the decision as to whether to pass on the information to the central nervous system takes place in the peripheral sensory system. We suggest that, through sensory adaptation, only alien signals are passed on to the brain, specifically to an “aggressive-behavior-switching center”, where the response is generated if the signal is above a certain threshold. PMID:26462936

  3. Parental effects in ecology and evolution: mechanisms, processes and implications

    PubMed Central

    Badyaev, Alexander V.; Uller, Tobias

    2009-01-01

    As is the case with any metaphor, parental effects mean different things to different biologists—from developmental induction of novel phenotypic variation to an evolved adaptation, and from epigenetic transference of essential developmental resources to a stage of inheritance and ecological succession. Such a diversity of perspectives illustrates the composite nature of parental effects that, depending on the stage of their expression and whether they are considered a pattern or a process, combine the elements of developmental induction, homeostasis, natural selection, epigenetic inheritance and historical persistence. Here, we suggest that by emphasizing the complexity of causes and influences in developmental systems and by making explicit the links between development, natural selection and inheritance, the study of parental effects enables deeper understanding of developmental dynamics of life cycles and provides a unique opportunity to explicitly integrate development and evolution. We highlight these perspectives by placing parental effects in a wider evolutionary framework and suggest that far from being only an evolved static outcome of natural selection, a distinct channel of transmission between parents and offspring, or a statistical abstraction, parental effects on development enable evolution by natural selection by reliably transferring developmental resources needed to reconstruct, maintain and modify genetically inherited components of the phenotype. The view of parental effects as an essential and dynamic part of an evolutionary continuum unifies mechanisms behind the origination, modification and historical persistence of organismal form and function, and thus brings us closer to a more realistic understanding of life's complexity and diversity. PMID:19324619

  4. 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/3 days) 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 55C 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

  5. On the elementary processes of protein crystallization: Bond selection mechanism

    NASA Astrophysics Data System (ADS)

    Nanev, Christo N.

    2014-09-01

    The paper explores the application of bond selection mechanism (BSM) in protein crystal growth; previously, BSM was employed to explain the slow rate of protein crystal nucleation, equilibrium crystal shape and energy barrier in nucleus formation (C.N. Nanev, Prog. Cryst. Growth Charact. Mater. 59 (2013) 133-169). Now, the elementary growth processes are considered from BSM perspective and the crystal growth shape is tackled, the latter resulting from a strong directional kinetic anisotropy in step advancement rates in different crystallographic directions. The most significant surface patterns of growing protein crystals, such as two-dimensional nuclei and growth spiral shapes observed by atomic force microscopy (AFM), are also considered. The activation barrier associated with entering of a protein molecule into the kink site is evaluated and the start of the kinetic roughening is established. Crystal lattice bond energies are estimated (being well above the thermal energy, kBT) from the supersaturation dependence of 2D- into 1D-nuclei transformation.

  6. Synchrony: a spiking-based mechanism for processing sensory stimuli.

    PubMed

    Glackin, Cornelius; Maguire, Liam; McDaid, Liam; Wade, John

    2012-08-01

    Synchronous behaviour of neurons is both beneficial and detrimental to the neural code. On the one extreme, synchronous firing activity is well known to be a symptom of epileptic seizures, whilst on the other synchrony provides a mechanism for coordinating brain activity. This paper briefly reviews some current thinking with regard to synchrony, and outlines some experiments with LIF neurons that harness near-synchronous states for processing biologically-realistic sensory stimuli. Inspired by the topology of neurons in the cochlear nucleus, laterally connected leaky integrate and fire neurons, operating in near-synchronous states, are investigated for their ability to reduce noisy spikes and increase spectral contrast of auditory stimuli. Two connectivity parameters, referred to as connection length and neighbourhood radius, are introduced to configure lateral inhibitory connectivity to generate this neural behaviour. Information-theoretic principles are then employed to quantify the information retained by the coding, and then this is compared to the information retained by the various output topologies. PMID:22377659

  7. Silver-clad ? superconducting tapes fabricated by different mechanical processing

    NASA Astrophysics Data System (ADS)

    Guo, Y. C.; Liu, H. K.; Dou, S. X.; Kuroda, T.; Tanaka, Y.

    1998-10-01

    0953-2048/11/10/032/img10/silver composites were fabricated by drawing a silver tube packed with precursor powders into round wire and deforming the round wire into flat tapes by longitudinal rolling, transverse rolling and uniaxial pressing respectively. The resultant tapes were observed by optical microscopy to examine the superconductor core/silver interface. Short pieces were cut from the tapes and heat-treated by a thermomechanical process consisting of alternate sintering and intermediate mechanical deformation. Intermediate deformation was carried out for each tape using the method by which the tape was formed. The effect of different deformations on the microstructure and transport property of the final tapes was investigated. It was found that deformation method affected the core/silver interface of tapes significantly. Pressing produced a wavier core/silver interface (sausaging) and more cracks than longitudinal and transverse rolling. As for critical current density, pressing yielded the highest value, due to the higher density and better grain alignment in the pressed tapes than in the longitudinal and transverse rolled ones.

  8. Fate of E. coli across mechanical dewatering processes.

    PubMed

    Monteleone, M C; Furness, D; Jefferson, B; Cartmell, E

    2004-07-01

    Five UK sludge treatment plants have been monitored for Escherichia coli (E.coli) variation after mechanical belt press and centrifuge dewatering processes. A complementary laboratory trial was also completed to examine the effects of varying centrifugal force on raw sludge E.coli content. An E.coli balance between the numbers contained in the flows entering and exiting four full scale centrifuge dewatering systems indicated a minimum 63 % increase in E.coli numbers between the input feed and sludge cake for a digested sludge input to the centrifuge. For two of the centrifuge sites this increase was statistically significant and corresponded to an increase in E.coli concentration ranging up to 1.4 Log after centrifugation. However, E.coli variation was found to be dependent on the type of sludge, as centrifuge dewatering of raw sludge at full scale resulted in a 40 % decrease in E.coli numbers. The complementary laboratory centrifuge work confirmed that E.coli numbers decreased in raw sludge after centrifugation. E.coli numbers were not observed to increase in digested sludge which had been dewatered using a belt press. A decrease of 44 % was observed. PMID:15346864

  9. Acoustic trapping of active matter.

    PubMed

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

    2016-01-01

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

  10. 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.

  11. Ion-trapping properties of SCRIT

    NASA Astrophysics Data System (ADS)

    Ogawara, R.; Ohnishi, T.; Togasaki, M.; Tamaki, S.; Miyashita, Y.; Takehara, H.; Koizumi, K.; Kurita, K.; Wakasugi, M.

    2013-12-01

    We have developed a novel internal target formation technique, SCRIT (Self-Confining Radioactive-isotope Ion Target) with the aim to achieve electron scattering off unstable nuclei. This technique is based on the ion trapping phenomenon in an electron storage ring. To establish the applicability of SCRIT as a target formation technique, we studied in detail its ion-trapping properties. We focused particularly on the spatial distribution of the trapped target ions and their behavior in time evolution. Over 90% of injected ions were trapped in SCRIT, and the overlap efficiency between the trapped target ion cloud and the electron beam was about 10%. From time evolution measurements and computer simulations, we found that variations in trapping lifetime depending on electron beam instability, space charge effect, and q/A values are crucial to understanding the ion-trapping mechanism of SCRIT.

  12. 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, Hlne; Kuhn, Isabelle; Cakir-Kiefer, Cline; 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

  13. 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.

  14. 40 CFR 408.240 - Applicability; description of the mechanized clam processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... mechanized clam processing subcategory. 408.240 Section 408.240 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Clam Processing Subcategory 408.240 Applicability; description of the mechanized clam processing subcategory. The provisions of this subpart are applicable to discharges...

  15. 40 CFR 408.240 - Applicability; description of the mechanized clam processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... mechanized clam processing subcategory. 408.240 Section 408.240 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Clam Processing Subcategory 408.240 Applicability; description of the mechanized clam processing subcategory. The provisions of this subpart are applicable to discharges...

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... mechanized blue crab processing subcategory. 408.30 Section 408.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30 Applicability; description of the mechanized blue crab processing subcategory. The provisions of this subpart are applicable to...

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... mechanized blue crab processing subcategory. 408.30 Section 408.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30 Applicability; description of the mechanized blue crab processing subcategory. The provisions of this subpart are applicable to...

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

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... mechanized blue crab processing subcategory. 408.30 Section 408.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30 Applicability; description of the mechanized blue crab processing subcategory. The provisions of this subpart are applicable to...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... mechanized blue crab processing subcategory. 408.30 Section 408.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30 Applicability; description of the mechanized blue crab processing subcategory. The provisions of this subpart are applicable to...

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... mechanized blue crab processing subcategory. 408.30 Section 408.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30 Applicability; description of the mechanized blue crab processing subcategory. The provisions of this subpart are applicable to...

  1. 40 CFR 408.240 - Applicability; description of the mechanized clam processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... mechanized clam processing subcategory. 408.240 Section 408.240 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Clam Processing Subcategory 408.240 Applicability; description of the mechanized clam processing subcategory. The provisions of this subpart are applicable to discharges...

  2. 40 CFR 408.240 - Applicability; description of the mechanized clam processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... mechanized clam processing subcategory. 408.240 Section 408.240 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Clam Processing Subcategory 408.240 Applicability; description of the mechanized clam processing subcategory. The provisions of this subpart are applicable to discharges...

  3. 40 CFR 408.240 - Applicability; description of the mechanized clam processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... mechanized clam processing subcategory. 408.240 Section 408.240 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Clam Processing Subcategory 408.240 Applicability; description of the mechanized clam processing subcategory. The provisions of this subpart are applicable to discharges...

  4. How varying pest and trap densities affect Tribolium castaneum (Coleoptera: Tenebrionidae) capture in pheromone traps

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is an important insect pest in food processing facilities. Pheromone trapping is frequently used to monitor red flour beetle populations in structures; however, the optimal trap density and the relationship between trap ...

  5. Oscillatory synchrony as a mechanism of attentional processing.

    PubMed

    Gregoriou, Georgia G; Paneri, Sofia; Sapountzis, Panagiotis

    2015-11-11

    The question of how the brain selects which stimuli in our visual field will be given priority to enter into perception, to guide our actions and to form our memories has been a matter of intense research in studies of visual attention. Work in humans and animal models has revealed an extended network of areas involved in the control and maintenance of attention. For many years, imaging studies in humans constituted the main source of a systems level approach, while electrophysiological recordings in non-human primates provided insight into the cellular mechanisms of visual attention. Recent technological advances and the development of sophisticated analytical tools have allowed us to bridge the gap between the two approaches and assess how neuronal ensembles across a distributed network of areas interact in visual attention tasks. A growing body of evidence suggests that oscillatory synchrony plays a crucial role in the selective communication of neuronal populations that encode the attended stimuli. Here, we discuss data from theoretical and electrophysiological studies, with more emphasis on findings from humans and non-human primates that point to the relevance of oscillatory activity and synchrony for attentional processing and behavior. These findings suggest that oscillatory synchrony in specific frequencies reflects the biophysical properties of specific cell types and local circuits and allows the brain to dynamically switch between different spatio-temporal patterns of activity to achieve flexible integration and selective routing of information along selected neuronal populations according to behavioral demands. This article is part of a Special Issue entitled SI: Prediction and Attention. PMID:25712615

  6. Temperature dependence of frequency dispersion in III-V metal-oxide-semiconductor C-V and the capture/emission process of border traps

    NASA Astrophysics Data System (ADS)

    Vais, Abhitosh; Lin, Han-Chung; Dou, Chunmeng; Martens, Koen; Ivanov, Tsvetan; Xie, Qi; Tang, Fu; Givens, Michael; Maes, Jan; Collaert, Nadine; Raskin, Jean-Pierre; DeMeyer, Kristin; Thean, Aaron

    2015-08-01

    This paper presents a detailed investigation of the temperature dependence of frequency dispersion observed in capacitance-voltage (C-V) measurements of III-V metal-oxide-semiconductor (MOS) devices. The dispersion in the accumulation region of the capacitance data is found to change from 4%-9% (per decade frequency) to 0% when the temperature is reduced from 300 K to 4 K in a wide range of MOS capacitors with different gate dielectrics and III-V substrates. We show that such significant temperature dependence of C-V frequency dispersion cannot be due to the temperature dependence of channel electrostatics, i.e., carrier density and surface potential. We also show that the temperature dependence of frequency dispersion, and hence, the capture/emission process of border traps can be modeled by a combination of tunneling and a "temperature-activated" process described by a non-radiative multi-phonon model, instead of a widely believed single-step elastic tunneling process.

  7. The kinetics and mechanics of ultrasonically-induced cell lysis produced by non-trapped bubbles in a rotating culture tube.

    PubMed

    Church, C C; Miller, M W

    1983-01-01

    The kinetics of ultrasonically-induced cell lysis are examined in terms of classical radiation biology target theory. A theoretical expression relating the concentration of intact cells remaining after a given period of sonication in a rotating culture tube to the number of non-trapped bubbles, l, which a cell must encounter in order to be lysed is obtained. The expression is compared to experimental results in order to determine the actual value of l. It is found that l equals one (1). The concentration of non-trapped bubbles which is responsible for the observed cell lysis is calculated to be 250-500 cm-3. Finally, it is proposed that non-trapped bubbles tunnel into cells while undergoing stable cavitation and that cell lysis is produced by one or more transient events inside the cell. PMID:6649157

  8. Characterization of Mechanical Properties of Aluminum Processed by Repetitive Corrugation and Straightening Process using Taguchi Analysis

    NASA Astrophysics Data System (ADS)

    Siddesha, H. S.; Shantharaja, M.

    2013-02-01

    The severe plastic deformation process is capable of developing the submicron grain structures in metallic alloys and to improve the mechanical properties. Repetitive corrugation and straightening (RCS) processes are widely used in industries to compensate the high-strength metal plates components used in automobiles. In this work, an attempt has been made to study the influence of RCS parameters like strain rate, number of passes, and plate thickness to produce grain refinement in metallic alloys. Experiments were based on the Taguchi method and the analysis of variance (ANOVA) technique was an effective tool to predict the degree of importance of the RCS parameters on grain size, microhardness, and tensile strength of RCS specimens. The results indicated that the number of passes has a major influence on the fine-grain refinement, followed by Al plate thickness and strain rate.

  9. QCD mechanisms of (semi)exclusive Drell-Yan processes

    SciTech Connect

    Pivovarov, A.A.; Teryaev, O.V.

    2015-04-10

    Two mechanisms for the lepton pair production in exclusive proton-meson collisions are considered and compared. Amplitudes and differential cross sections are calculated. The interference of these mechanisms is taken into account. The skewness dependence of the result is discussed.

  10. 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.

  11. 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.

  12. Bacterial trapping in shear

    NASA Astrophysics Data System (ADS)

    Rusconi, Roberto; Guasto, Jeffrey S.; Stocker, Roman

    2012-11-01

    Bacteria are ubiquitously exposed to flow, both in natural environments and artificial devices (e.g., catheters), where confining surfaces create non-uniform shear. While the effects of shear on passive particles are well understood, little is known about the consequences of shear on motile bacteria. We exposed bacteria having different motility strategies (e.g., run-and-tumble, run-and-reverse) to microfluidic Poiseuille flows and quantified the swimming kinematics and cell distribution in the channel using video-microscopy. We discovered that the coupling of motility and a spatially varying shear results in a dramatic trapping of motile cells in high-shear regions, and conversely a strong depletion in the low-shear portion of the channel. We demonstrate experimentally that this trapping process is robust across species such as Bacillus subtilis and Pseudomonas aeruginosa, and can have far-reaching consequences on bacterial transport, by (i) counteracting bacterial chemotactic responses; and (ii) enhancing surface attachment and thus biofilm formation by trapping cells near walls. More generally, this work shows that-despite the low Reynolds number-the coupling of flow and self-propulsion can be nonlinear and not simply a superposition of the two effects.

  13. Process optimization and consumable development for Chemical Mechanical Planarization (CMP) processes

    NASA Astrophysics Data System (ADS)

    Mudhivarthi, Subrahmanya R.

    Chemical Mechanical Planarization (CMP) is one of the most critical processing steps that enables fabrication of multilevel interconnects. The success of CMP process is limited by the implementation of an optimized process and reduction of process generated defects along with post CMP surface characteristics such as dishing and erosion. This thesis investigates to identify various sources of defects and studies the effect of factors that can be used to optimize the process. The major contributions of this work are: Understanding the effect of temperature rise on surface tribology, electrochemistry and post CMP pattern effects during the CMP process; investigating the effect of pad conditioning temperature and slurry flow rate on tribology and post CMP characteristics; development of novel slurries using polymer hybrid particles and improvement in slurry metrology to reduce surface damage during CMP. From the current research, it was shown that the effect of temperature on CMP tribology is predominantly affected by the polishing parameters and the polishing pad characteristics more than the chemical nature of the slurry. The effect of temperature is minimal on the resulting surface roughness but the with-in die non-uniformity is significantly affected by the temperature at the interface. Secondly, in this research it was shown that the effectiveness and aggressiveness of the pad conditioning process is highly influenced by the conditioning temperature. This aspect can be utilized to optimize the parameters for the pad conditioning process. Further, post CMP characteristics such as dishing, erosion and metal loss on patterned samples were shown to decrease with increase in slurry flow rate. This research then concentrates on the development of novel low defect slurry using polymer hybrid abrasive particles. Several varieties of surface functionalized polymer particles were employed to make oxide CMP slurries. These novel slurries proved to be potential candidates to reduce surface damage during CMP as they resulted in low coefficient of friction and much less surface scratches as compared to conventional abrasives. Thus, this research helps to reduce defects and non-planarity issues during CMP process thereby improving yield and reducing the cost of ownership.

  14. Scalable Designs for Planar Ion Trap Arrays

    NASA Astrophysics Data System (ADS)

    Slusher, R. E.

    2007-03-01

    Recent progress in quantum operations with trapped ion qubits has been spectacular for qubit counts up to approximately ten ions. Two qubit quantum gates, quantum error correction, simple quantum algorithms and entanglement of up to 8 qubits have been demonstrated by groups including those at NIST, University of Michigan, University of Innsbruck and Oxford. Interesting problems in quantum information processing including quantum simulations of condensed matter systems and quantum repeaters for long distance quantum communication systems require hundreds or thousands of qubits. Initial designs for an ion trap ``Quantum CCD'' using spatially multiplexed planar ion traps as well as initial experiments using planar ion traps are promising routes to scaling up the number of trapped ions to more interesting levels. We describe designs for planar ion traps fabricated using silicon VLSI techniques. This approach allows the control voltages required for the moving and positioning the ions in the array to be connected vertically through the silicon substrate to underlying CMOS electronics. We have developed techniques that allow the ion trap structures to be fabricated monolithically on top of the CMOS electronics. The planar traps have much weaker trapping depths than the more conventional multi-level traps. However, the trap depths are still adequate for trapping hot ions from many ion sources. The planar traps also involve more complex configurations for laser cooling and micromotion control. Initial solutions to these problems will be presented. Laser access to the ions can be provided by laser beams grazing the trap surface or by using vertical slots through the trap chip. We will also discuss limits imposed by power dissipation and ion transport through trap junctions (e.g. crosses and Ys). We have fabricated these VLSI based traps in a number of configurations. Initial fabrication and packaging challenges will be discussed. D. Kielpinski, C. Monroe, and D.J. Wineland, ``Architecture for a large-scale ion-trap quantum computer,'' Nature, Vol.417, pp.709--711, (2002). S. Seidelin, J. Chiaverini, R. Reicle, J. J. Bollinger, D. Leibfried, J. Briton, J. H. Wesenberg, R. B. Blakestad, R. J. Epstein, D. B. Hume, J. D. Jost, C. Langer, R. Ozeri, N. Shiga, and D. J. Wineland, ``Amicrofabricated surface-electrode ion trap for scalable quantum informtion processing,'' quant-ph/0601173, (2006). J. Kim, S. Pau, Z. Ma, H.R. McLellan, J.V. Gates, A. Kornblit, and R.E. Slusher, ``System design for large-scale ion trap quantum information processor,'' Quantum Inf. Comput., Vol 5, pp 515--537, (2005).

  15. Processing, microstructure, and mechanical behavior of titanium dioxide nanotubes

    NASA Astrophysics Data System (ADS)

    Crawford, Grant Alan

    Titanium dioxide nanotubes are of considerable interest for use in hydrogen generation, solar cells, chemical sensors, and bioactive coatings. In this study, nanotube coatings were fabricated on a Ti substrate via anodic oxidation. A novel hierarchical coating consisting of nanotubes (˜50 nm diameter) on the nano-scale and large pores/pits (˜1-20 mum) on the micro-scale was developed. This coating has potential for use as a bioactive coating on Ti bone implants. The mechanisms for nanotube formation and microscopic pitting were discussed. Microstructure characterization was conducted using scanning electron microscopy, focused ion beam, transmission electron microscopy, and image analysis. The effect of processing variables (i.e. time, temperature, pH) on nanotube characteristics (i.e. diameter, wall thickness, length) and hierarchical structure (i.e. pit/pore size and density) was studied. Anodization time was found to affect nanotube length and microscopic pit size and density. Lowering the electrolyte pH decreased the nanotube length and microscopic pit density. Increasing electrolyte temperature decreased nanotube length and increased pit/pore density. Anodization time, pH, and temperature, showed little effect on nanotube diameter or wall thickness. Microscopic pitting in the nanotube coating was found to occur above grain boundaries in the Ti substrate and above Ti grains with (0001) orientation. It was discovered that neighboring nanotubes are connected by ridges on the tube walls and an incoherent interface is formed between crystalline Ti and amorphous titanium dioxide. The influence of Ti substrate orientation on the growth kinetics and nanotube morphology was examined. Ti grains with surface orientations near (0001) experience retarded nanotube growth compared to (xxx0) orientations. This orientation dependence is likely related to differences in atomic density. Conventional nanoindentation and interfacial force microscopy (IFM), was employed to probe the hardness, Young's modulus and deformation behavior of the nanotube coatings. From conventional nanoindentation, elastic modulus decreased for thinner coatings. Using IFM, coating modulus was measured with minimal contribution from the Ti substrate and estimated to be 4-30 GPa. During nanoindentation, nanotubes deform by tube crushing, resulting in an increase in local oxide density. Increased density causes an increase in indentation modulus from roughly 4-30 GPa in the first 50 nm of indentation.

  16. 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.

  17. 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.

  18. Processing effects on the mechanical properties of tungsten heavy alloys

    NASA Technical Reports Server (NTRS)

    Kishi, Toshihito; German, R. M.

    1990-01-01

    Tungsten heavy alloys exhibit significant mechanical property sensitivities to the fabrication variables. These sensitivities are illustrated in this examination of vacuum sintering and the effects of composition, sintering temperature, and sintering time on the mechanical properties of tungsten heavy alloys. Measurements were conducted to assess the density, strength, hardness, and elongation dependencies. A detrimental aspect of vacuum sintering is matrix phase evaporation, although vacuum sintering does eliminate the need for postsintering heat treatments.

  19. 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.

  20. 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

  1. Exospheric transport restrictions on water ice in lunar polar traps

    NASA Technical Reports Server (NTRS)

    Hodges, R. R., Jr.

    1991-01-01

    There is little doubt that at least 10 exp 17 g of water has accreted on the moon as a result of the reduction of ferric iron at the regolith surface by solar wind protons, the vaporization of chondrites, and perhaps comet impacts. Lacking an efficient escape mechanism, most of this water (or its progeny) is probably on the moon now. If the water were to have migrated to permanently shaded cold traps near the lunar poles, ice deposts with densities greater than 1000 g/sq cm would cover the traps, providing accessible resources. However, exospheric transport considerations suggest that the actual amount of water ice in the cold traps is probably too small to be of practical interest. The alternative is global assimilation of most of the water into the regolith, a process that must account for about 30 micromoles of water per gram of soil.

  2. 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.

  3. On biodiversity conservation and poverty traps

    PubMed Central

    Barrett, Christopher B.; Travis, Alexander J.; Dasgupta, Partha

    2011-01-01

    This paper introduces a special feature on biodiversity conservation and poverty traps. We define and explain the core concepts and then identify four distinct classes of mechanisms that define important interlinkages between biodiversity and poverty. The multiplicity of candidate mechanisms underscores a major challenge in designing policy appropriate across settings. This framework is then used to introduce the ensuing set of papers, which empirically explore these various mechanisms linking poverty traps and biodiversity conservation. PMID:21873176

  4. Trapped Inflation

    SciTech Connect

    Green, Daniel; Horn, Bart; Senatore, Leonardo; 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.

  5. Trapping polar molecules in an ac trap

    SciTech Connect

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

    2006-12-15

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

  6. Mechanical Behavior and Processing of DS and Single Crystal Superalloys

    NASA Astrophysics Data System (ADS)

    Khan, T.; Caron, P.; Nakagawa, Y. G.

    1986-07-01

    This article examines mechanical anisotropy of single crystals, cold work induced surface recrystallization on directionally solidified (DS) materials, and the effect of temperature gradient in a DS furnace on the fatigue strength of single crystals. It draws attention to the highly anisotropic creep behavior of some modern single crystal alloys showing, in particular, extremely poor creep resistance in the <111> orientation. Effects of surface recrystallization on the creep strength are evaluated. The present work incites further investigation on heat treatments and alloy chemistry modifications in order to reduce the effect of mechanical anisotropy. Great care should be taken during the "mechanical" handling of DS or single crystal components to avoid surface recrystallization. HIP'ing or high gradient solidification are shown to be two possible ways for enhancing the durability and the fatigue strength of single crystal superalloys. In certain liquid fuel rocket engine applications, where hydrogen embrittlement of single crystal turbopump blades can be of concern, both these techniques can be useful.

  7. Drug trapping and delivery for Alzheimer's diagnosis.

    PubMed

    Jalil, M A; Kamoldilok, Surachart; Saktioto, T; Ong, C T; Yupapin, Preecha P

    2012-10-01

    In this investigation, a new design based on a PANDA ring resonator as an optical trapping tool for tangle protein, molecular motor storage, and delivery is proposed. The optical vortices are generated and the trapping mechanism is controlled in the same way as the conventional optical tweezers. The trapping force is produced by a combination of the gradient field and scattering photons. The required molecular volume is trapped and moved dynamically within the molecular network. The tangle protein and molecular motor can be transported and delivered to the required destinations for Alzheimer's diagnosis by molecular buffer and bus network. PMID:22384850

  8. FINAL REPORT. AQUEOUS ELECTROCHEMICAL MECHANISMS IN ACTINIDE RESIDUE PROCESSING

    EPA Science Inventory

    Plutonium and uranium residues (e.g., incinerator ash, combustibles, and sand/slag/crucibles) resulting from the purification and processing of nuclear materials constitute an enormous volume of lean processing waste and represent a significant fraction of the U. S. Department of...

  9. Mechanisms of Verbal Morphology Processing in Heritage Speakers of Russian

    ERIC Educational Resources Information Center

    Romanova, Natalia

    2008-01-01

    The goal of the study is to analyze the morphological processing of real and novel verb forms by heritage speakers of Russian in order to determine whether it differs from that of native (L1) speakers and second language (L2) learners; if so, how it is different; and which factors may guide the acquisition process. The experiment involved three

  10. 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.

  11. Fluid mechanics mechanisms in the stall process of airfoils for helicopters

    NASA Technical Reports Server (NTRS)

    Young, W. H., Jr.

    1981-01-01

    Phenomena that control the flow during the stall portion of a dynamic stall cycle are analyzed, and their effect on blade motion is outlined. Four mechanisms by which dynamic stall may be initiated are identified: (1) bursting of the separation bubble, (2) flow reversal in the turbulent boundary layer on the airfoil upper surface, (3) shock wave-boundary layer interaction behind the airfoil crest, and (4) acoustic wave propagation below the airfoil. The fluid mechanics that contribute to the identified flow phenomena are summarized, and the usefulness of a model that incorporates the required fluid mechanics mechanisms is discussed.

  12. 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…

  13. 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

  14. Elementary Quantum Mechanics in a High-Energy Process

    ERIC Educational Resources Information Center

    Denville, A.; And Others

    1978-01-01

    Compares two approaches to strong absorption in elementary quantum mechanics; the black sphere and a model based on the continuum theory of nuclear reactions. Examines the application to proton-antiproton interactions at low momenta and concludes that the second model is the appropriate and simplest to use. (Author/GA)

  15. 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.

  16. Direct observation of closed magnetic flux trapped in the high-latitude magnetosphere.

    PubMed

    Fear, R C; Milan, S E; Maggiolo, R; Fazakerley, A N; Dandouras, I; Mende, S B

    2014-12-19

    The structure of Earth's magnetosphere is poorly understood when the interplanetary magnetic field is northward. Under this condition, uncharacteristically energetic plasma is observed in the magnetotail lobes, which is not expected in the textbook model of the magnetosphere. Using satellite observations, we show that these lobe plasma signatures occur on high-latitude magnetic field lines that have been closed by the fundamental plasma process of magnetic reconnection. Previously, it has been suggested that closed flux can become trapped in the lobe and that this plasma-trapping process could explain another poorly understood phenomenon: the presence of auroras at extremely high latitudes, called transpolar arcs. Observations of the aurora at the same time as the lobe plasma signatures reveal the presence of a transpolar arc. The excellent correspondence between the transpolar arc and the trapped closed flux at high altitudes provides very strong evidence of the trapping mechanism as the cause of transpolar arcs. PMID:25525244

  17. Direct observation of closed magnetic flux trapped in the high-latitude magnetosphere

    NASA Astrophysics Data System (ADS)

    Fear, R. C.; Milan, S. E.; Maggiolo, R.; Fazakerley, A. N.; Dandouras, I.; Mende, S. B.

    2014-12-01

    The structure of Earths magnetosphere is poorly understood when the interplanetary magnetic field is northward. Under this condition, uncharacteristically energetic plasma is observed in the magnetotail lobes, which is not expected in the textbook model of the magnetosphere. Using satellite observations, we show that these lobe plasma signatures occur on high-latitude magnetic field lines that have been closed by the fundamental plasma process of magnetic reconnection. Previously, it has been suggested that closed flux can become trapped in the lobe and that this plasma-trapping process could explain another poorly understood phenomenon: the presence of auroras at extremely high latitudes, called transpolar arcs. Observations of the aurora at the same time as the lobe plasma signatures reveal the presence of a transpolar arc. The excellent correspondence between the transpolar arc and the trapped closed flux at high altitudes provides very strong evidence of the trapping mechanism as the cause of transpolar arcs.

  18. Pupillary contagion: central mechanisms engaged in sadness processing

    PubMed Central

    Harrison, Neil A.; Singer, Tania; Rotshtein, Pia; Dolan, Ray J.; Critchley, Hugo D.

    2006-01-01

    Empathic responses underlie our ability to share emotions and sensations with others. We investigated whether observed pupil size modulates our perception of other's emotional expressions and examined the central mechanisms modulated by incidental perception of pupil size in emotional facial expressions. We show that diminishing pupil size enhances ratings of emotional intensity and valence for sad, but not happy, angry or neutral facial expressions. This effect was associated with modulation of neural activity within cortical and subcortical regions implicated in social cognition. In an identical context, we show that the observed pupil size was mirrored by the observers own pupil size. This empathetic contagion engaged the brainstem pupillary control nuclei (EdingerWestphal) in proportion to individual subject's sensitivity to this effect. These findings provide evidence that perceptionaction mechanisms extend to non-volitional operations of the autonomic nervous system. PMID:17186063

  19. Characterization of Exciton Self-trapping in Amorphous Silica

    SciTech Connect

    Van Ginhoven, Renee M.; Jonsson, Hannes; Corrales, Louis R.

    2006-07-15

    Triplet electron-hole excitations were introduced into amorphous silica to study self-trapping (localization) and damage formation using density functional theory. Multiple self-trapped exciton (STE) states are found that can be differentiated based on the luminescence energy, the localization and distribution of the excess spin density of the triplet state, and relevant structural data, including the presence or absence of broken bonds. The trapping is shown to be affected by the relaxation response of the silica network, and by comparing results of quartz and amorphous silica systems the effects of the inherent disordered structures on exciton self-trapping are revealed. A key result is that during the process of the exciton trapping, point defects are formed as a result of a non-activated damage mechanism where the triplet energy surface and the corresponding ground state singlet surface come into close proximity. This work was supported by the Office of Basic Energy Sciences of the Department of Energy, in part by the Chemical Sciences program and in part by the Engineering and Geosciences Division. The Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy under contract DE-AC05-76RL01830.

  20. Computational Mechanics of Input-Output Processes: Structured Transformations and the ɛ -Transducer

    NASA Astrophysics Data System (ADS)

    Barnett, Nix; Crutchfield, James P.

    2015-10-01

    Computational mechanics quantifies structure in a stochastic process via its causal states, leading to the process's minimal, optimal predictor—the ɛ {{-}}machine. We extend computational mechanics to communication channels coupling two processes, obtaining an analogous optimal model—the ɛ {{-}}transducer—of the stochastic mapping between them. Here, we lay the foundation of a structural analysis of communication channels, treating joint processes and processes with input. The result is a principled structural analysis of mechanisms that support information flow between processes. It is the first in a series on the structural information theory of memoryful channels, channel composition, and allied conditional information measures.

  1. 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.

  2. 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, Grard; 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.

  3. Thalamic Circuit Mechanisms Link Sensory Processing in Sleep and Attention

    PubMed Central

    Chen, Zhe; Wimmer, Ralf D.; Wilson, Matthew A.; Halassa, Michael M.

    2016-01-01

    The correlation between sleep integrity and attentional performance is normally interpreted as poor sleep causing impaired attention. Here, we provide an alternative explanation for this correlation: common thalamic circuits regulate sensory processing across sleep and attention, and their disruption may lead to correlated dysfunction. Using multi-electrode recordings in mice, we find that rate and rhythmicity of thalamic reticular nucleus (TRN) neurons are predictive of their functional organization in sleep and suggestive of their participation in sensory processing across states. Surprisingly, TRN neurons associated with spindles in sleep are also associated with alpha oscillations during attention. As such, we propose that common thalamic circuit principles regulate sensory processing in a state-invariant manner and that in certain disorders, targeting these circuits may be a more viable therapeutic strategy than considering individual states in isolation. PMID:26778969

  4. Processing and mechanical properties of lightweight structural composites

    SciTech Connect

    Lewandowski, J.J.

    1989-01-01

    The properties of discontinuous metal-matrix composites depend sensitively on a variety of processing parameters, including choice of reinforcement and type (e.g. plate, particulate, whisker), volume percent reinforcement, size and size distribution of reinforcement, as well as matrix of characteristics and properties. Techniques available to incorporate reinforcement into potential matrices include casting, powder metallurgy, as well as spray-deposition, techniques. In addition, post-processing treatments such as thermomechanical treatment and heat treatment may be particularly important in producing optimum properties. This paper reviews recent work that has focused on structure-property relationships in aluminum alloy metal-matrix systems. 33 references, 6 figures.

  5. 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

  6. Volatile Release From The Siberian Traps Inferred From Melt Inclusions

    NASA Astrophysics Data System (ADS)

    Black, Benjamin A.; Elkins-Tanton, Linda T.; Rowe, Michael C.; Ukstins Peate, Ingrid

    2010-05-01

    The Siberian Traps Large Igneous Province is one of the largest known continental flood volcanic provinces in the Phanerozoic. The quantification of volatile degassing is particularly important because the Siberian Traps have often been invoked as a possible trigger for the end-Permian mass extinction (e.g. Campbell et al., 1992; Wignall, 2001). Volatile degassing provides a crucial mechanism to link mafic volcanic eruption with global environmental change. Mafic flood basalt magmas are expected to have low volatile contents (similar to mid-ocean ridge basalts). However, Siberian Traps magmas were chambered in and erupted through a thick sedimentary basin and may have interacted with, and obtained volatiles from, sedimentary lithologies such as limestone, coal, and evaporite. Melt inclusions from the Siberian Traps provide insight into the potential total volatile budget throughout the evolution of the large igneous province. These droplets of trapped melt may preserve volatile species that would otherwise have degassed at the time of eruption. We present data from the analysis of more than 100 melt inclusions, including both homogenized inclusions and rare glassy inclusions with low crystallinity. Many melt inclusions from tuffs and flows near the base of the Siberian Traps sequence are substantially enriched in chlorine and fluorine compared to Deccan Traps and Laki melt inclusions (Self et al., 2008; Thordarson et al., 1996). These inclusions record chlorine concentrations up to ~1400 ppm, and fluorine concentrations up to ~5000 ppm. Olivines from the Maymechinsky suite, recognized as the last extrusive products of Siberian Traps volcanism, contain melt inclusions with maximum sulfur concentrations in the range of ~5000 ppm and substantial concentrations of chlorine. Intrusive igneous rocks from the province also display significant volatile contents. A sill from the Ust-Ilimsk region yielded plagioclase-hosted melt inclusions which contain chlorine and fluorine concentrations in the range of one weight percent. Visscher et al. (2004) proposed that chlorofluorocarbon compounds (CFCs) may have played a major role in the terrestrial end-Permian extinction. These CFCs are powerful catalysts for the breakdown of ozone, a process which can expose the biosphere to increased ultraviolet radiation. Measurements of elevated chlorine and fluorine from the Siberian Traps may thus provide a concrete source for CFCs that could have triggered this kill mechanism.

  7. 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.

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

    PubMed

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

    2014-06-01

    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

  9. Orientation processing mechanisms revealed by the plaid tilt illusion

    NASA Technical Reports Server (NTRS)

    Smith, S.; Wenderoth, P.; van der Zwan, R.

    2001-01-01

    The tilt after-effect (TAE) and tilt illusion (TI) have revealed a great deal about the nature of orientation coding of 1-dimensional (1D) lines and gratings. Comparatively little research however has addressed the mechanisms responsible for encoding the orientation of 2-dimensional (2D) plaid stimuli. A multi-stage model of edge detection has recently been proposed [Georgeson, M. A. (1998) Image & Vision Computing, 16(6-7), 389-405] to account for the perceived structure of a plaid stimulus that incorporates extraction of the zero-crossings (ZCs) of the plaid. Data is presented showing that the ZCs of a plaid inducing stimulus can interact with vertical grating test stimulus to induce a standard tilt illusion. However, by considering the second-order structure of a plaid rather than ZCs, it was shown that the perceived orientation of the vertical test grating results from the combination of orientation illusions due to the first- and second-order components of an inducing plaid. The data suggest that the mechanisms encoding the orientation of second-order contours are similar to, and interact directly with, those that encode first-order contours.

  10. Excitation of Transverse Dipole and Quadrupole Modes in a Pure Ion Plasma in a Linear Paul Trap to Study Collective Processes in Intense Beams

    NASA Astrophysics Data System (ADS)

    Gilson, Erik

    2012-10-01

    Transverse dipole and quadrupole modes have been excited in a one-component cesium ion plasma trapped in the Paul Trap Simulator Experiment (PTSX) in order to characterize their properties, and understand the effect of their excitation on equivalent long-distance beam propagation. The PTSX device is a compact laboratory Paul trap that simulates the transverse dynamics of a long, intense charge bunch propagating through an alternating-gradient transport system by putting the physicist in the beam's frame of reference. A pair of arbitrary function generators was used to apply trapping voltage waveform perturbations with a range of frequencies and, by changing which electrodes were driven with the perturbation, with either a dipole or quadrupole spatial structure. The results presented in this paper explore the dependence of the perturbation voltage's effect on the amount of trapped charge, the perturbation duration and amplitude. Perturbations were also applied that simulate the effect of random lattice errors that exist in an accelerator with quadrupole magnets that are misaligned or have variance in their field strength. The experimental results quantify the growth in the equivalent transverse beam emittance that occurs due to the applied noise and demonstrate that the random lattice errors interact with the trapped plasma through the plasma's internal collective modes. Coherent periodic perturbations were applied to simulate the effects of magnet errors in circular machines such as storage rings. The trapped one component plasma is strongly affected when the perturbation frequency is commensurate with a plasma mode frequency. The experimental results, which help to understand the physics of quiescent intense beam propagation over large distances, are compared with analytic models and particle-in-cell simulations.

  11. Personal Computer (PC) based image processing applied to fluid mechanics

    NASA Technical Reports Server (NTRS)

    Cho, Y.-C.; Mclachlan, B. G.

    1987-01-01

    A PC based image processing system was employed to determine the instantaneous velocity field of a two-dimensional unsteady flow. The flow was visualized using a suspension of seeding particles in water, and a laser sheet for illumination. With a finite time exposure, the particle motion was captured on a photograph as a pattern of streaks. The streak pattern was digitized and processed using various imaging operations, including contrast manipulation, noise cleaning, filtering, statistical differencing, and thresholding. Information concerning the velocity was extracted from the enhanced image by measuring the length and orientation of the individual streaks. The fluid velocities deduced from the randomly distributed particle streaks were interpolated to obtain velocities at uniform grid points. For the interpolation a simple convolution technique with an adaptive Gaussian window was used. The results are compared with a numerical prediction by a Navier-Stokes computation.

  12. Reconstruction of mechanically recorded sound by image processing

    SciTech Connect

    Fadeyev, Vitaliy; Haber, Carl

    2003-03-26

    Audio information stored in the undulations of grooves in a medium such as a phonograph record may be reconstructed, with no or minimal contact, by measuring the groove shape using precision metrology methods and digital image processing. The effects of damage, wear, and contamination may be compensated, in many cases, through image processing and analysis methods. The speed and data handling capacity of available computing hardware make this approach practical. Various aspects of this approach are discussed. A feasibility test is reported which used a general purpose optical metrology system to study a 50 year old 78 r.p.m. phonograph record. Comparisons are presented with stylus playback of the record and with a digitally re-mastered version of the original magnetic recording. A more extensive implementation of this approach, with dedicated hardware and software, is considered.

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

    DOEpatents

    Coronado, Paul R.; Poco, John F.

    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.

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

    DOEpatents

    Coronado, Paul R.; Poco, John F.

    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.

  15. 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.

  16. Neurobehavioral Mechanisms of Temporal Processing Deficits in Parkinson's Disease

    PubMed Central

    Harrington, Deborah L.; Castillo, Gabriel N.; Greenberg, Paul A.; Song, David D.; Lessig, Stephanie; Lee, Roland R.; Rao, Stephen M.

    2011-01-01

    Background Parkinson's disease (PD) disrupts temporal processing, but the neuronal sources of deficits and their response to dopamine (DA) therapy are not understood. Though the striatum and DA transmission are thought to be essential for timekeeping, potential working memory (WM) and executive problems could also disrupt timing. Methodology/Findings The present study addressed these issues by testing controls and PD volunteers ‘on’ and ‘off’ DA therapy as they underwent fMRI while performing a time-perception task. To distinguish systems associated with abnormalities in temporal and non-temporal processes, we separated brain activity during encoding and decision-making phases of a trial. Whereas both phases involved timekeeping, the encoding and decision phases emphasized WM and executive processes, respectively. The methods enabled exploration of both the amplitude and temporal dynamics of neural activity. First, we found that time-perception deficits were associated with striatal, cortical, and cerebellar dysfunction. Unlike studies of timed movement, our results could not be attributed to traditional roles of the striatum and cerebellum in movement. Second, for the first time we identified temporal and non-temporal sources of impaired time perception. Striatal dysfunction was found during both phases consistent with its role in timekeeping. Activation was also abnormal in a WM network (middle-frontal and parietal cortex, lateral cerebellum) during encoding and a network that modulates executive and memory functions (parahippocampus, posterior cingulate) during decision making. Third, hypoactivation typified neuronal dysfunction in PD, but was sometimes characterized by abnormal temporal dynamics (e.g., lagged, prolonged) that were not due to longer response times. Finally, DA therapy did not alleviate timing deficits. Conclusions/Significance Our findings indicate that impaired timing in PD arises from nigrostriatal and mesocortical dysfunction in systems that mediate temporal and non-temporal control-processes. However, time perception impairments were not improved by DA treatment, likely due to inadequate restoration of neuronal activity and perhaps corticostriatal effective-connectivity. PMID:21364772

  17. Investigation of the Quenching Mechanism of a Fluorescence Process

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Egolf, Debra; Kuhl, Dennis

    2010-04-01

    The properties and behavior of an electronic excited state were investigated experimentally. The goal was to determine whether, upon interaction with a series of molecules Q, (i.e., 1,2,4-trimethoxybenzene, 1,4-dimethoxybenzene, naphthalene), the fluorescent states of 9,10-dicyanoanthracene and 9-cyanoanthracene are quenched via an electron transfer process. A Stern-Volmer investigation enables evaluation of the rate constant, kq, for quenching of the cyanoanthracene excited state. Then a Rehm-Weller plot of kq vs. Gibbs energy of electron transfer, ?Get, allows determination of the Gibbs energy of activation, ?Get^., and the rate constant, ket, for the electron transfer process. UV-visible and fluorescence spectroscopy, cyclic voltammetry, laser-based kinetic analyses, and computer modeling were used in this investigation. Now that the electron transfer process previously reported for these chemical systems has been validated using our methods, future investigations will involve manipulation of various experimental parameters (i.e., anthracene sustituents, solvent polarity, etc.).

  18. 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.

  19. Mechanism of silk processing in insects and spiders.

    PubMed

    Jin, Hyoung-Joon; Kaplan, David L

    2003-08-28

    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 (100-200 nm 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. PMID:12944968

  20. Mechanical behaviour and formation process of silkworm silk gut.

    PubMed

    Cenis, Jos L; Madurga, Rodrigo; Aznar-Cervantes, Salvador D; Lozano-Prez, A Abel; Mar-Buy, Nria; Meseguer-Olmo, Luis; Plaza, Gustavo R; Guinea, Gustavo V; Elices, Manuel; Del Pozo, Francisco; Prez-Rigueiro, Jos

    2015-12-14

    High performance silk fibers were produced directly from the silk glands of silkworms (Bombyx mori) following an alternative route to natural spinning. This route is based on a traditional procedure that consists of soaking the silk glands in a vinegar solution and stretching them by hand leading to the so called silkworm guts. Here we present, to the authors' best knowledge, the first comprehensive study on the formation, properties and microstructure of silkworm gut fibers. Comparison of the tensile properties and microstructural organization of the silkworm guts with those of naturally spun fibers allows gain of a deeper insight into the mechanisms that lead to the formation of the fiber, as well as the relationship between the microstructure and properties of these materials. In this regard, it is proved that an acidic environment and subsequent application of tensile stress in the range of 1000 kPa are sufficient conditions for the formation of a silk fiber. PMID:26403149

  1. Modality-independent neural mechanisms for novel phonetic processing.

    PubMed

    Williams, Joshua T; Darcy, Isabelle; Newman, Sharlene D

    2015-09-16

    The present study investigates whether the inferior frontal gyrus is activated for phonetic segmentation of both speech and sign. Early adult second language learners of Spanish and American Sign Language at the very beginning of instruction were tested on their ability to classify lexical items in each language based on their phonetic categories (i.e., initial segments or location parameter, respectively). Conjunction analyses indicated that left-lateralized inferior frontal gyrus (IFG), superior parietal lobule (SPL), and precuneus were activated for both languages. Common activation in the left IFG suggests a modality-independent mechanism for phonetic segmentation. Additionally, common activation in parietal regions suggests spatial preprocessing of audiovisual and manuovisual information for subsequent frontal recoding and mapping. Taken together, we propose that this frontoparietal network is involved in domain-general segmentation of either acoustic or visual signal that is important to novel phonetic segmentation. PMID:25988835

  2. Sorption vacuum trap

    NASA Technical Reports Server (NTRS)

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

    1970-01-01

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

  3. Stratigraphic traps 1

    SciTech Connect

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

    1990-01-01

    A spectrum of trap types exists. On one end of this spectrum are traps that exist only because of stratigraphic elements. On the other end of the spectrum are traps that exist only because of structural elements. Pure structural traps are not as common as one might suppose. In a pure structural trap the hydrocarbon/water contact parallels the structure contours completely around the trap. A majority of traps have an element of lateral stratigraphic control: they exist due to a combination of structure and stratigraphy. In these traps the hydrocarbon/water contact does not parallel the structure contours. This book contains studies of fields that have traps that are either purely stratigraphic or that combine stratigraphic and structural elements. In this volume, traps that are nearly pure stratigraphic traps include those of Albion-Scipio (Michigan basin), Kasim and Walio (Salawati basin), Jameson (Permian basin), Frigg (North Sea basin), Berlin (Anadarko basin), and Hoadley (Alberta basin). The trap of albion-Scipio field resulted from development of porosity due to dolomitization of a limestone along a preexisting strike-slip fault system.

  4. Ion trap simulation tools.

    SciTech Connect

    Hamlet, Benjamin Roger

    2009-02-01

    Ion traps present a potential architecture for future quantum computers. These computers are of interest due to their increased power over classical computers stemming from the superposition of states and the resulting capability to simultaneously perform many computations. This paper describes a software application used to prepare and visualize simulations of trapping and maneuvering ions in ion traps.

  5. Feshbach resonance cooling of trapped atom pairs

    SciTech Connect

    Dunn, Josh W.; Borca, Bogdan; Greene, Chris H.; Blume, D.; Granger, B.E.

    2005-03-01

    Spectroscopic studies of few-body systems at ultracold temperatures provide valuable information that often cannot be extracted in a hot environment. Considering a pair of atoms, we propose a cooling mechanism that makes use of a scattering Feshbach resonance. Application of a series of time-dependent magnetic field ramps results in either zero, one, or two atoms remaining trapped. If two atoms remain in the trap after the field ramps are completed, then they have been cooled. Application of the proposed cooling mechanism to optical traps or lattices is considered.

  6. 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.

  7. Neutron Trapping using a Magneto-Gravitational Trap

    NASA Astrophysics Data System (ADS)

    Liu, Chen-Yu

    2014-03-01

    Eighty years after Chadwick discovered the neutron, physicists today still cannot agree on how long the neutron lives. Measurements of the neutron lifetime have achieved the 0.1% level of precision (~ 1 s). However, results from several recent experiments are up to 7 s lower than the (pre-2010) particle data group (PDG) value. Experiments using the trap technique yield lifetime results lower than those using the beam technique. The PDG urges the community to resolve this discrepancy, now 6.5 sigma. Measuring the absolute neutron lifetime is difficult because of several limitations: the low energy of the neutron decay products, the inability to track slow neutrons, and the fact that the neutron lifetime is long (880.1 +/- 1.1 s). Slow neutrons are susceptible to many loss mechanisms other than beta-decay, such as upscattering and absorption on material surfaces. Often, these interactions act on time scales comparable to the neutron beta-decay, making the extraction of the beta-decay lifetime particularly challenging. We will revisit this measurement by trapping ultracold neutrons (UCN) in a hybrid magnetic-gravitational trap. The trap consists of a Halbach array of permanent magnets, which can levitate UCN up to 50 neV. These neutrons are also confined vertically up to 0.5 m by gravity. Such a trap minimizes the chance of neutron interactions with material walls. In addition, the open-top geometry allows room to implement novel schemes to detect neutrons and decay particles in-situ. The UCN ? experiment aims to reduce the uncertainty of the neutron lifetime measurement to below 1 second. In this talk, I will report results of our first attempt to trap UCN in 2013 and discuss plans to quantify systematic effects. The work is supported by NSF grant PHY-1306942.

  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 Mller [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. Processed wastewater sludge for improvement of mechanical properties of concretes.

    PubMed

    Barrera-Daz, Carlos; Martnez-Barrera, Gonzalo; Gencel, Osman; Bernal-Martnez, Lina A; Brostow, Witold

    2011-08-15

    Two problems are addressed simultaneously. One is the utilisation of sludge from the treatment of wastewater. The other is the modification of the mechanical properties of concrete. The sludge was subjected to two series of treatments. In one series, coagulants were used, including ferrous sulphate, aluminium sulphate or aluminium polyhydroxychloride. In the other series, an electrochemical treatment was applied with several starting values of pH. Then, concretes consisting of a cement matrix, silica sand, marble and one of the sludges were developed. Specimens without sludge were prepared for comparison. Curing times and aggregate concentrations were varied. The compressive strength, compressive strain at yield point, and static and dynamic elastic moduli were determined. Diagrams of the compressive strength and compressive strain at the yield point as a function of time passed through the minima as a function of time for concretes containing sludge; therefore, the presence of sludge has beneficial effects on the long term properties. Some morphological changes caused by the presence of sludge are seen in scanning electron microscopy. A way of utilising sludge is thus provided together with a way to improve the compressive strain at yield point of concrete. PMID:21616593

  11. Excitation of transverse dipole and quadrupole modes in a pure ion plasma in a linear Paul trap to study collective processes in intense beams

    SciTech Connect

    Gilson, Erik P.; Davidson, Ronald C.; Efthimion, Philip C.; Majeski, Richard; Startsev, Edward A.; Wang, Hua; Koppell, Stewart; Talley, Matthew

    2013-05-15

    Transverse dipole and quadrupole modes have been excited in a one-component cesium ion plasma trapped in the Paul Trap Simulator Experiment (PTSX) in order to characterize their properties and understand the effect of their excitation on equivalent long-distance beam propagation. The PTSX device is a compact laboratory Paul trap that simulates the transverse dynamics of a long, intense charge bunch propagating through an alternating-gradient transport system by putting the physicist in the beam's frame of reference. A pair of arbitrary function generators was used to apply trapping voltage waveform perturbations with a range of frequencies and, by changing which electrodes were driven with the perturbation, with either a dipole or quadrupole spatial structure. The results presented in this paper explore the dependence of the perturbation voltage's effect on the perturbation duration and amplitude. Perturbations were also applied that simulate the effect of random lattice errors that exist in an accelerator with quadrupole magnets that are misaligned or have variance in their field strength. The experimental results quantify the growth in the equivalent transverse beam emittance that occurs due to the applied noise and demonstrate that the random lattice errors interact with the trapped plasma through the plasma's internal collective modes. Coherent periodic perturbations were applied to simulate the effects of magnet errors in circular machines such as storage rings. The trapped one component plasma is strongly affected when the perturbation frequency is commensurate with a plasma mode frequency. The experimental results, which help to understand the physics of quiescent intense beam propagation over large distances, are compared with analytic models.

  12. Excitation of transverse dipole and quadrupole modes in a pure ion plasma in a linear Paul trap to study collective processes in intense beamsa)

    NASA Astrophysics Data System (ADS)

    Gilson, Erik P.; Davidson, Ronald C.; Efthimion, Philip C.; Majeski, Richard; Startsev, Edward A.; Wang, Hua; Koppell, Stewart; Talley, Matthew

    2013-05-01

    Transverse dipole and quadrupole modes have been excited in a one-component cesium ion plasma trapped in the Paul Trap Simulator Experiment (PTSX) in order to characterize their properties and understand the effect of their excitation on equivalent long-distance beam propagation. The PTSX device is a compact laboratory Paul trap that simulates the transverse dynamics of a long, intense charge bunch propagating through an alternating-gradient transport system by putting the physicist in the beam's frame of reference. A pair of arbitrary function generators was used to apply trapping voltage waveform perturbations with a range of frequencies and, by changing which electrodes were driven with the perturbation, with either a dipole or quadrupole spatial structure. The results presented in this paper explore the dependence of the perturbation voltage's effect on the perturbation duration and amplitude. Perturbations were also applied that simulate the effect of random lattice errors that exist in an accelerator with quadrupole magnets that are misaligned or have variance in their field strength. The experimental results quantify the growth in the equivalent transverse beam emittance that occurs due to the applied noise and demonstrate that the random lattice errors interact with the trapped plasma through the plasma's internal collective modes. Coherent periodic perturbations were applied to simulate the effects of magnet errors in circular machines such as storage rings. The trapped one component plasma is strongly affected when the perturbation frequency is commensurate with a plasma mode frequency. The experimental results, which help to understand the physics of quiescent intense beam propagation over large distances, are compared with analytic models.

  13. Enterobacter cloacae as biosurfactant producing bacterium: differentiating its effects on interfacial tension and wettability alteration Mechanisms for oil recovery during MEOR process.

    PubMed

    Sarafzadeh, Pegah; Hezave, Ali Zeinolabedini; Ravanbakhsh, Moosa; Niazi, Ali; Ayatollahi, Shahab

    2013-05-01

    Microbial enhanced oil recovery (MEOR) process utilizes microorganisms or their metabolites to mobilize the trapped oil in the oil formation after primary and secondary oil recovery stages. MEOR technique is considered as more environmentally friendly and low cost process. There are several identified mechanisms for more oil recovery using MEOR processes however; wettability alteration and interfacial tension (IFT) reduction are the important ones. Enterobacter Cloacae, a facultative bio-surfactant producer bacterium, was selected as a bacterial formulation due to its known performance on IFT reduction and wettability alteration. To quantify the effects of these two mechanisms, different tests including oil spreading, in situ and ex situ core flooding, wettability measurement (Amott), IFT, viscosity and pH measurements were performed. The obtained results revealed that the experimental procedure used in this study was able to quantitatively identify the individual effects of both mechanisms on the ultimate microbial oil recovery. The results demonstrated considerable effects of both mechanisms on the tertiary oil recovery; however after a proper shut in time period, more tertiary oil was recovered because of wettability alteration mechanism. Finally, SEM images taken from the treated cores showed biofilm formation on the rock pore surfaces, which is responsible for rock surface wettability alteration. PMID:23376749

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

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... mechanical processing. 318.18 Section 318.18 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... PREPARATION OF PRODUCTS General § 318.18 Handling of certain material for mechanical processing. Material to... food product except that it may be held prior to such use for no more than 72 hours at 40 °F. (4...

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

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Handling of certain material for mechanical processing. 318.18 Section 318.18 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... PREPARATION OF PRODUCTS General 318.18 Handling of certain material for mechanical processing. Material...

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

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Handling of certain material for mechanical processing. 318.18 Section 318.18 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... PREPARATION OF PRODUCTS General 318.18 Handling of certain material for mechanical processing. Material...

  17. 9 CFR 318.18 - Handling of certain material for mechanical processing.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Handling of certain material for mechanical processing. 318.18 Section 318.18 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... PREPARATION OF PRODUCTS General 318.18 Handling of certain material for mechanical processing. Material...

  18. 9 CFR 318.18 - Handling of certain material for mechanical processing.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Handling of certain material for mechanical processing. 318.18 Section 318.18 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... PREPARATION OF PRODUCTS General 318.18 Handling of certain material for mechanical processing. Material...

  19. Hydrogen trapping in graphite materials in various conditions

    NASA Astrophysics Data System (ADS)

    Begrambekov, L. B.; Ayrapetov, A. A.; Sadovskiy, Ya A.; Shigin, P. A.

    2016-01-01

    The paper presents a short revue of the study of not been investigated specific features of hydrogen trapping in graphite occurring as the results of inelastic interaction of impinging ions with carbon materials (potential trapping). The influence of potential mechanism on different regularities of hydrogen trapping are considered. Among them there is trapping dependence on irradiating ion current density, ion energy, irradiation fluence, temperature of the investigated samples and oxygen addition in the plasma.

  20. 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)

  1. New evidence for geomagnetically trapped anomalous cosmic rays

    NASA Technical Reports Server (NTRS)

    Cummings, J. R.; Cummings, A. C.; Mewaldt, R. A.; Selesnick, R. S.; Stone, E. C.; Von Rosenvinge, T. T.

    1993-01-01

    We report new observations of 15 MeV/nuc or greater trapped heavy ions with Z equal to or greater than 2, made on the polar-orbiting SAMPEX spacecraft in late 1992 and early 1993. A trapped population that includes He, N, O, and Ne is found to be located at L = 2. We conclude that the observed N, O, and Ne ions are 'anomalous' cosmic rays, trapped by the mechanism proposed by Blake and Friesen (1977). While it is not expected that this mechanism would also trap anomalous He, the characteristics of the trapped He population are generally consistent with those of N, O, and Ne.

  2. Dynamical mechanisms of odor processing in olfactory bulb mitral cells.

    PubMed

    Rubin, Daniel B; Cleland, Thomas A

    2006-08-01

    In the olfactory system, the contribution of dynamical properties such as neuronal oscillations and spike synchronization to the representation of odor stimuli is a matter of substantial debate. While relatively simple computational models have sufficed to guide current research in large-scale network dynamics, less attention has been paid to modeling the membrane dynamics in bulbar neurons that may be equally essential to sensory processing. We here present a reduced, conductance-based compartmental model of olfactory bulb mitral cells that exhibits the complex dynamical properties observed in these neurons. Specifically, model neurons exhibit intrinsic subthreshold oscillations with voltage-dependent frequencies that shape the timing of stimulus-evoked action potentials. These oscillations rely on a persistent sodium conductance, an inactivating potassium conductance, and a calcium-dependent potassium conductance and are reset via inhibitory input such as that delivered by periglomerular cell shunt inhibition. Mitral cells fire bursts, or clusters, of spikes when continuously stimulated. Burst properties depend critically on multiple currents, but a progressive deinactivation of I(A) over the course of a burst is an important regulator of burst termination. Each of these complex properties exhibits appropriate dynamics and pharmacology as determined by electrophysiological studies. Additionally, we propose that a second, inconsistently observed form of infrathreshold bistability in mitral cells may derive from the activation of ATP-activated potassium currents responding to hypoxic conditions. We discuss the integration of these cellular properties in the larger context of olfactory bulb network operations. PMID:16707721

  3. 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 1450C. Texture is highly developed in samples with no dopant and 0.14 wt% dopant by 1550C and in samples with 2 wt% dopant by 1350C. 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 included in the non templated tapes, which are subsequently stacked, laminated, and co-sintered. Appropriate dopant concentrations and sintering conditions that enable the production of well-textured layers and fine-grained equiaxed layers seperated by a sharp interface were identified. It was found that densification and microstructure development within textured and equiaxed layers is affected by changes in both differential sintering stress and dopant diffusion distance associated with layer thickess and the volume percent of textured layers within the composite. Significant crack deflection was observed during bend testing of composites with porous textured layers (2-5 vol% porosity), resulting in highly non-catastrophic failure (with W.O.F. up to 1 kJ/m2). Crack deflection, often millimeters in length, occurred along the basal faces of templated grains within the textured. Textured layers that deflect cracks (i.e. those with porosity) had significantly lower interfacial fracture energies than textured layers that do not deflect cracks (i.e. those without porosity). It was determined that crack deflection is a composite effect and the result of the combination of the anisotropic fracture energy of textured Al2O3 and the residual compressive stresses developed from thermal expansion mismatch. Other observed fracture phenomena include multiple cracking/crack arrest and preliminary evidence of flaw tolerance. Textured-equiaxed Al2O3 microstructure composites of additional connectivities, (including 1-3, 0-3, and 3-3) were produced by screen printing and co-casting processes. Template alignment during the screen printing process was demonstrated, allowing the capability to print complex textured features. Co-casting was used to produce single tapes with templated and non-templated segments. A variety of stacking strategies were employed to generate various 1-3 and 3-3 composites (including cross-ply composites). Observations during fracture testing of complex composites included non-catastrophic failure without crack deflection and improved delamination resistance.

  4. Toolkit for the Automated Characterization of Optical Trapping Forces on Microscopic Particles

    NASA Astrophysics Data System (ADS)

    Glaser, Joseph; Hoeprich, David; Resnick, Andrew

    2014-03-01

    Optical traps have been in use in microbiological studies for the past 40 years to obtain noninvasive control of microscopic particles. However, the magnitude of the applied forces is often unknown. Therefore, we have developed an automated data acquisition and processing system which characterizes trap properties for known particle geometries. Extensive experiments and measurements utilizing well-characterized objects were performed and compared to literature to confirm the system's performance. This system will enable the future analysis of a trapped primary cilium, a slender rod-shaped organelle with aspect ratio L/R >30, where `L' is the cilium length and `R' the cilium diameter. The trapping of cilia is of primary importance, as it will lead to the precise measurements of mechanical properties of the organelle and its significance to the epithelial cell. Support from the National Institutes of Health, 1R15DK092716 is gratefully acknowledged.

  5. Reduction of trapped-ion anomalous heating by in situ surface plasma cleaning

    NASA Astrophysics Data System (ADS)

    McConnell, Robert; Bruzewicz, Colin; Chiaverini, John; Sage, Jeremy

    2015-08-01

    Anomalous motional heating is a major obstacle to scalable quantum information processing with trapped ions. Although the source of this heating is not yet understood, several previous studies suggest that noise due to surface contaminants is the limiting heating mechanism in some instances. We demonstrate an improvement by a factor of 4 in the room-temperature heating rate of a niobium surface electrode trap by in situ plasma cleaning of the trap surface. This surface treatment was performed with a simple homebuilt coil assembly and commercially available matching network and is considerably gentler than other treatments, such as ion milling or laser cleaning, that have previously been shown to improve ion heating rates. We do not see an improvement in the heating rate when the trap is operated at cryogenic temperatures, pointing to a role of thermally activated surface contaminants in motional heating whose activity may freeze out at low temperatures.

  6. Processing, characterization and mechanical properties of alumina-based nanocomposites

    NASA Astrophysics Data System (ADS)

    Thomson, Katherine E.

    2007-12-01

    The present study focuses on improving the fracture toughness of nanocrystalline alumina by incorporating second phases---specifically niobium and carbon nanotubes. Ceramics have many properties that lend themselves well to load bearing and armor applications. Chemical inertness, high hardness and strength, low wear rates and low densities are examples of these properties that warrant potential substitution of metals and their alloys. In this study, nanocrystalline alumina was investigated based on its impressive elevated temperature properties and high hardness. Despite these promising structural properties, pure nanocrystalline alumina has low fracture toughness (2.5 MPa*m1/2) and is thus limited to non-structural applications. Alumina-based nanocomposites reinforced with niobium and/or carbon nanotubes (CNT) were fabricated by advanced powder processing techniques and consolidated by spark plasma sintering (1200C, 4 min). Raman spectroscopy revealed that single-walled carbon nanotubes (SWCNTs) begin to break down at sintering temperatures above 1150C. Nuclear magnetic resonance (NMR) showed that, although thermodynamically unlikely, no Al4C3 was formed in the CNT-alumina nanocomposites. Thus, the nanocomposite is purely a physical mixture and no chemical bond was formed between the nanotubes and matrix. In addition, in-situ 3-pt and standard 4-pt bend tests were conducted on niobium and/or carbon nanotube-reinforced alumina nanocomposites in order to assess their toughness. Although stable crack growth was not achieved in the 3-pt bend testing, average fracture toughness vales of 6.1 and 3.3 MPam 1/2 were measured for 10 vol%Nb and 10 vol%Nb-5 vol%SWCNT-alumina, respectively. The 4-pt bend testing measured average intrinsic fracture toughness of 2.95, 2.76, 3.33 and 3.95 MPam1/2 for alumina nanocomposites containing 5 vol%SWCNT, 10 vol%SWCNT, 5 vol%DWCNT and 10 vol% Nb, respectively. Although nanocrystalline alumina will never be able to compete with its microcrystalline counter part in terms of fracture toughness, its nanocomposite form does have a niche in small components and devices requiring high hardness and conductivity---perhaps in the IC industry. Adding SWCNTs to nanocrystalline alumina increases the electrical conductivity 13 orders of magnitude without degradation of intrinsic fracture toughness and with a very small decrease in hardness.

  7. Microstructure and Mechanical Properties of Ultra-Fine Grain Al-Zr Alloy Fabricated by Mechanical Alloying Process.

    PubMed

    Kim, Chung Seok; Kim, Il-Ho

    2015-08-01

    The ultra-fine grain Al-4Zr alloy has been successfully fabricated by a mechanical alloying process. The intermetallic Al3Zr phases strongly enhance the mechanical properties of Al-based alloy and prevent grain growth of alloy. The phase stability and transformation during mechanical alloying process have been investigated. The ultra-fine grain alloy has been successfully obtained. The thin film of Al-4Zr alloy has been observed by a transmission electron microscope. The equivalent grain size of as-milling specimen is 55 nm. After milling process, the specimens were heat treated at 350 C to 650 C. The equivalent grain size of heat treated specimens were 80 nm at 350 C and 130 nm at 650 C. Some of Zr atoms were dissolved into the Al matrix and most of them reacted with hydrogen produced by decomposition of PCA to form ZrH2 during mechanical alloying process. These ZrH2 hydrides decomposed gradually after the heat treatment. Stable A13Zr with a D023 structure was formed by heat treatment at temperature of 550 C. PMID:26369209

  8. Experimental investigation of supercritical CO2 trapping mechanisms at the Intermediate Laboratory Scale in well-defined heterogeneous porous media

    SciTech Connect

    Trevisan, Luca; Pini, Ronny; Cihan, Abdullah; Birkholzer, Jens T.; Zhou, Quanlin; Illangasekare, Tissa H.

    2014-12-31

    The heterogeneous nature of typical sedimentary formations can play a major role in the propagation of the CO2 plume, eventually dampening the accumulation of mobile phase underneath the caprock. From core flooding experiments, it is also known that contrasts in capillary threshold pressure due to different pore size can affect the flow paths of the invading and displaced fluids and consequently influence the build- up of non-wetting phase (NWP) at interfaces between geological facies. The full characterization of the geologic variability at all relevant scales and the ability to make observations on the spatial and temporal distribution of the migration and trapping of supercritical CO2 is not feasible from a practical perspective. To provide insight into the impact of well-defined heterogeneous systems on the flow dynamics and trapping efficiency of supercritical CO2 under drainage and imbibition conditions, we present an experimental investigation at the meter scale conducted in synthetic sand reservoirs packed in a quasi-two-dimensional flow-cell. Two immiscible displacement experiments have been performed to observe the preferential entrapment of NWP in simple heterogeneous porous media. The experiments consisted of an injection, a fluid redistribution, and a forced imbibition stages conducted in an uncorrelated permeability field and a homogeneous base case scenario. We adopted x-ray attenuation analysis as a non-destructive technique that allows a precise measurement of phase saturations throughout the entire flow domain. By comparing a homogeneous and a heterogeneous scenario we have identified some important effects that can be attributed to capillary barriers, such as dampened plume advancement, higher non-wetting phase saturations, larger contact area between the injected and displaced phases, and a larger range of non-wetting phase saturations.

  9. 3-D Modelling of Electromagnetic, Thermal, Mechanical and Metallurgical Couplings in Metal Forming Processes

    SciTech Connect

    Chenot, Jean-Loup; Bay, Francois

    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.

  10. Volatile Release from the Siberian Traps Inferred from Melt Inclusions

    NASA Astrophysics Data System (ADS)

    Black, B. A.; Elkins-Tanton, L. T.; Rowe, M. C.; Ukstins Peate, I.

    2009-12-01

    The Siberian Traps Large Igneous Province is one of the largest known continental flood volcanic provinces in the Phanerozoic. The quantification of volatile degassing is particularly important because the Siberian Traps have often been invoked as a possible trigger for the end-Permian mass extinction (e.g. Campbell et al., 1992; Wignall, 2001). Volatile degassing provides a crucial mechanism to link mafic volcanic eruption to global environmental change. Mafic flood basalt magmas are expected to have low volatile contents (similar to mid-ocean ridge basalts). However, Siberian Traps magmas were chambered in and erupted through a thick sedimentary basin and may have interacted with, and obtained volatiles from, sedimentary lithologies such as limestone, coal, and evaporite. Melt inclusions from the Siberian Traps provide insight into the potential total volatile budget throughout the evolution of the large igneous province. These droplets of trapped melt may preserve volatile species that would otherwise have degassed at the time of eruption (Thordarson et al., 1996). Mafic pyroclastic deposits from the lowermost Arydzhangsky suite (basal Siberian Traps) contain clinopyroxene phenocrysts hosting melt inclusions. Electron microprobe analysis of clinopyroxene-hosted re-homogenized melt inclusions indicates maximum measured concentrations of up to 1500 - 2000 ppm sulfur, 500 - 760 ppm chlorine, and 1900 - 2400 ppm fluorine. Olivines from the Maymechinsky suite, recognized as the last extrusive products of Siberian Traps volcanism, contain melt inclusions with maximum sulfur concentrations in the range of 5000 ppm, and less substantial concentrations of chlorine and fluorine. Intrusive igneous rocks from the province also display significant volatile contents. A sill from the Ust-Ilimsk region yielded plagioclase-hosted melt inclusions which contain chlorine and fluorine concentrations nearing one weight percent. Visscher et al. (2004) proposed that chlorofluorocarbon compounds (CFCs) may have played a major role in the terrestrial end-Permian extinction. These CFCs are powerful catalysts for the breakdown of ozone, a process which can expose the biosphere to increased ultraviolet radiation. Measurements of elevated chlorine and fluorine from the Siberian Traps may thus provide a concrete source for CFCs that could have triggered this kill mechanism.

  11. Generic equilibration dynamics of planar defects in trapped atomic superfluids

    NASA Astrophysics Data System (ADS)

    Scherpelz, Peter; Padavi?, Karmela; Murray, Andy; Glatz, Andreas; Aranson, Igor S.; Levin, K.

    2015-03-01

    We investigate equilibration processes shortly after sudden perturbations are applied to ultracold trapped superfluids. We show the similarity of phase imprinting and localized density depletion perturbations, both of which initially are found to produce "phase walls." These planar defects are associated with a sharp gradient in the phase. Importantly they relax following a quite general sequence. Our studies, based on simulations of the complex time-dependent Ginzburg-Landau equation, address the challenge posed by these experiments: how a superfluid eventually eliminates a spatially extended planar defect. The processes involved are necessarily more complex than equilibration involving simpler line vortices. An essential mechanism for relaxation involves repeated formation and loss of vortex rings near the trap edge.

  12. 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.

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

    SciTech Connect

    Casada, M.L.; Remson, A.C.; Yerger, C.M.

    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.

  14. Fastest predators in the plant kingdom: functional morphology and biomechanics of suction traps found in the largest genus of carnivorous plants

    PubMed Central

    Poppinga, Simon; Weisskopf, Carmen; Westermeier, Anna Sophia; Masselter, Tom; Speck, Thomas

    2016-01-01

    Understanding the physics of plant movements, which describe the interplay between plant architecture, movement speed and actuation principles, is essential for the comprehension of important processes like plant morphogenesis. Recent investigations especially on rapid plant movements at the interface of biology, physics and engineering sciences highlight how such fast motions can be achieved without the presence of muscles, nerves and technical hinge analogies. The suction traps (bladders) of carnivorous bladderworts (Utricularia spp., Lentibulariaceae, Lamiales) are considered as some of the most elaborate moving structures in the plant kingdom. A complex interplay of morphological and physiological adaptations allows the traps to pump water out of their body and to store elastic energy in the deformed bladder walls. Mechanical stimulation by prey entails opening of the otherwise watertight trapdoor, followed by trap wall relaxation, sucking in of water and prey, and consecutive trapdoor closure. Suction can also occur spontaneously in non-stimulated traps. We review the current state of knowledge about the suction trap mechanism with a focus on architectonically homogeneous traps of aquatic bladderwort species from section Utricularia (the so-called ‘Utricularia vulgaris trap type’). The functional morphology and biomechanics of the traps are described in detail. We discuss open questions and propose promising aspects for future studies on these sophisticated ultra-fast trapping devices. PMID:26602984

  15. Fastest predators in the plant kingdom: functional morphology and biomechanics of suction traps found in the largest genus of carnivorous plants.

    PubMed

    Poppinga, Simon; Weisskopf, Carmen; Westermeier, Anna Sophia; Masselter, Tom; Speck, Thomas

    2015-01-01

    Understanding the physics of plant movements, which describe the interplay between plant architecture, movement speed and actuation principles, is essential for the comprehension of important processes like plant morphogenesis. Recent investigations especially on rapid plant movements at the interface of biology, physics and engineering sciences highlight how such fast motions can be achieved without the presence of muscles, nerves and technical hinge analogies. The suction traps (bladders) of carnivorous bladderworts (Utricularia spp., Lentibulariaceae, Lamiales) are considered as some of the most elaborate moving structures in the plant kingdom. A complex interplay of morphological and physiological adaptations allows the traps to pump water out of their body and to store elastic energy in the deformed bladder walls. Mechanical stimulation by prey entails opening of the otherwise watertight trapdoor, followed by trap wall relaxation, sucking in of water and prey, and consecutive trapdoor closure. Suction can also occur spontaneously in non-stimulated traps. We review the current state of knowledge about the suction trap mechanism with a focus on architectonically homogeneous traps of aquatic bladderwort species from section Utricularia (the so-called 'Utricularia vulgaris trap type'). The functional morphology and biomechanics of the traps are described in detail. We discuss open questions and propose promising aspects for future studies on these sophisticated ultra-fast trapping devices. PMID:26602984

  16. Acoustic trapping of active matter

    PubMed Central

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

    2016-01-01

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

  17. Microfabricated ion trap array

    DOEpatents

    Blain, Matthew G. (Albuquerque, NM); Fleming, James G. (Albuquerque, NM)

    2006-12-26

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

  18. Attraction of walking Tribolium castaneum adults to traps

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The red flour beetle, Tribolium castaneum (Herbst), is a major pest of food processing facilities and can be monitored using pitfall type traps. To determine how beetles interact with these traps under field situations, the behavior of individual beetles released in the vicinity of traps was observe...

  19. 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.

  20. Trap-induced photoconductivity in singlet fission pentacene diodes

    SciTech Connect

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

    2014-07-21

    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.

  1. 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.

  2. Applications of microelectromagnetic traps.

    PubMed

    Basore, Joseph R; Baker, Lane A

    2012-06-01

    Microelectromagnetic traps (METs) have been used for almost two decades to manipulate magnetic fields. Different trap geometries have been shown to produce distinct magnetic fields and field gradients. Initially, microelectromagnetic traps were used mainly to separate and concentrate magnetic material at small scales. Recently such traps have been implemented for unique applications, for example filterless bioseparations, inductive heat generation, and biological detection. In this review, we describe recent reports in which MET geometry, current density, or external fields have been used. Descriptions of recent applications in which METs have been used to develop sensors, manipulate DNA, or block ion current are also provided. PMID:22562543

  3. Microparticle trapping in an ultrasonic Bessel beam

    PubMed Central

    Choe, Youngki; Kim, Jonathan W.; Shung, K. Kirk; Kim, Eun Sok

    2011-01-01

    This paper describes an acoustic trap consisting of a multi-foci Fresnel lens on 127??m thick lead zirconate titanate sheet. The multi-foci Fresnel lens was designed to have similar working mechanism to an Axicon lens and generates an acoustic Bessel beam, and has negative axial radiation force capable of trapping one or more microparticle(s). The fabricated acoustic tweezers trapped lipid particles ranging in diameter from 50 to 200??m and microspheres ranging in diameter from 70 to 90??m at a distance of 2 to 5?mm from the tweezers without any contact between the transducer and microparticles. PMID:22247566

  4. Microparticle trapping in an ultrasonic Bessel beam.

    PubMed

    Choe, Youngki; Kim, Jonathan W; Shung, K Kirk; Kim, Eun Sok

    2011-12-01

    This paper describes an acoustic trap consisting of a multi-foci Fresnel lens on 127??m thick lead zirconate titanate sheet. The multi-foci Fresnel lens was designed to have similar working mechanism to an Axicon lens and generates an acoustic Bessel beam, and has negative axial radiation force capable of trapping one or more microparticle(s). The fabricated acoustic tweezers trapped lipid particles ranging in diameter from 50 to 200??m and microspheres ranging in diameter from 70 to 90??m at a distance of 2 to 5?mm from the tweezers without any contact between the transducer and microparticles. PMID:22247566

  5. Microparticle trapping in an ultrasonic Bessel beam

    NASA Astrophysics Data System (ADS)

    Choe, Youngki; Kim, Jonathan W.; Shung, K. Kirk; Kim, Eun Sok

    2011-12-01

    This paper describes an acoustic trap consisting of a multi-foci Fresnel lens on 127 ?m thick lead zirconate titanate sheet. The multi-foci Fresnel lens was designed to have similar working mechanism to an Axicon lens and generates an acoustic Bessel beam, and has negative axial radiation force capable of trapping one or more microparticle(s). The fabricated acoustic tweezers trapped lipid particles ranging in diameter from 50 to 200 ?m and microspheres ranging in diameter from 70 to 90 ?m at a distance of 2 to 5 mm from the tweezers without any contact between the transducer and microparticles.

  6. Trapping effects in irradiated and avalanche-injected MOS capacitors

    NASA Technical Reports Server (NTRS)

    Bakowski, M.; Cockrum, R. H.; Zamani, N.; Maserjian, J.; Viswanathan, C. R.

    1978-01-01

    The trapping parameters for holes, and for electrons in the presence of trapped holes, have been measured from a set of wafers with different oxide thickness processed under controlled conditions. The trap cross-sections and densities indicate at least three trap species, including an interfacial species, a dominant bulk species which is determined to tail off from the silicon interface, and a third, lower density bulk species that is distributed throughout the oxide.

  7. Inexpensive, floating, insect-emergence trap

    SciTech Connect

    Cushman, R.M.

    1983-11-01

    The Environmental Sciences Division of Oak Ridge National Laboratory has been investigating the usefulness of aquarium microcosms and ponds for the quantification and predictions of toxicant effects on freshwater systems. Ideally, concepts and methods applicable to both 150-L microcosms and 15,000-L ponds would bridge the gap between the two. The effort of processing the benthic samples, as well as the destructiveness of the sampling in small ponds, limited the number of samples that could be taken. Therefore, the author developed an inexpensive emergence trap appropriate for use in small outdoor ponds, as one method of increasing sampling efficiency and economy. To prevent the possibility of trapping adults from adjacent ponds, which would confound the results, the traps had to be designed such that they could only trap insects from the ponds upon which they were floating. The design of this trap is described.

  8. 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.

  9. Proceedings of the 30th mechanical working and steel processing conference

    SciTech Connect

    Not Available

    1989-01-01

    This book contains the proceedings of the 30th mechanical working and steel processing conference. Topics covered include: tubular products, bar, rod, and semifinishing products, flat rolled products, heavy forgings, roll technology, and coatings.

  10. Mirror mechanism and dedicated circuits are the scaffold for mirroring processes.

    PubMed

    Fogassi, Leonardo

    2014-04-01

    In the past decade many studies have demonstrated the existence of a mirror mechanism that matches the sensory representation of a biological stimulus with its somatomotor and visceromotor representation. This mechanism, likely phylogenetically very old, explains several types of mirroring behaviours, at different levels of complexity. The presence in primates of dedicated neuroanatomical pathways for specific sensorimotor integrations processes implies, at least in the primate lineage, a hard-wired mirror mechanism for social cognitive functions. PMID:24775155

  11. Mechanisms Underlying Lexical Access in Native and Second Language Processing of Gender and Number Agreement

    ERIC Educational Resources Information Center

    Romanova, Natalia

    2013-01-01

    Despite considerable evidence suggesting that second language (L2) learners experience difficulties when processing morphosyntactic aspects of L2 in online tasks, the mechanisms underlying these difficulties remain unknown. The aim of this dissertation is to explore possible causes for the difficulties by comparing attentional mechanisms engaged

  12. 42 CFR 433.116 - FFP for operation of mechanized claims processing and information retrieval systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 4 2014-10-01 2014-10-01 false FFP for operation of mechanized claims processing and information retrieval systems. 433.116 Section 433.116 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL ASSISTANCE PROGRAMS STATE FISCAL ADMINISTRATION Mechanized Claims...

  13. 42 CFR 433.116 - FFP for operation of mechanized claims processing and information retrieval systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 4 2012-10-01 2012-10-01 false FFP for operation of mechanized claims processing and information retrieval systems. 433.116 Section 433.116 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL ASSISTANCE PROGRAMS STATE FISCAL ADMINISTRATION Mechanized Claims...

  14. Developmental Changes in Speed of Processing: Central Limiting Mechanism or Skill Transfer?

    ERIC Educational Resources Information Center

    Stigler, James W.; And Others

    1988-01-01

    Examines Kail's argument that similarity in developmental speed-of-processing curves for name retrieval and mental rotation indicates that performance on a wide range of cognitive tasks is constrained by growth of a central limiting mechanism. Results suggest that operation of this mechanism is neither sufficient nor necessary to generate the

  15. Trapped ion arrays for quantum simulation

    NASA Astrophysics Data System (ADS)

    Slusher, Richart

    2011-03-01

    Trapped ions have been used to demonstrate a broad range of quantum information processes with high fidelity and are an obvious choice for quantum simulations. Several quantum simulations have already been demonstrated with ions. , The present goal is to simulate quantum systems that cannot be achieved with classical computation using more than 20 ions. It is challenging to assemble more than 20 ions in suitable arrays for quantum simulation of arbitrary model systems. Present ion trap based quantum simulations with up to 20 ions are now in progress. This talk describes ion trap micro-fabrication techniques and designs that have the potential to increase the number of coupled ions to the range between 50 and 100 ions. High precision ion traps are fabricated using silicon VLSI techniques on silicon wafers with aluminum electrodes. At the Georgia Tech Research Institute we are designing, fabricating and testing ion trap arrays that will contain and accurately control at least 50 ions in linear chains of equally spaced ions. Large numbers of equally spaced ions have recently been shown to be stable in anharmonic trap potentials that are easily obtained in the micro-fabricated traps. The limits on quantum simulation accuracy due to errors in the ion trap parameters will be discussed. Supported by IARPA and DARPA.

  16. Optical trapping map of dielectric spheres.

    PubMed

    Muradoglu, Murat; Ng, Tuck Wah

    2013-05-20

    Many applications use a focused Gaussian laser beam to manipulate spherical dielectric particles. The axial trapping efficiency of this process is a function of (i) the particle radius r, (ii) the ratio of the refractive index of particle over the medium, and (iii) the numerical aperture of the delivered light beam. During what we believe is the first comprehensive simulation of its kind, we uncovered optical trapping regions in the three-dimensional (3D) parameter space forming an iso-surface landscape with ridge-like contours. Using specific points in the parameter space, we drew attention to difficulties in using the trapping efficiency and stiffness metrics in defining how well particles are drawn into and held in the trap. We have proposed an alternative calculation based on the maximum forward and restoration values of the trapping efficiency in the axial sense, called the trapping quality. We also discuss the manner in which the ridge regions may be harnessed for effective particle sorting, how the optical trapping blind spots can be used in applications that seek to eschew photothermal damage, and how trapping can proceed when many parameters change, such as when swelling occurs. PMID:23736236

  17. Enhancement of tunability of MAPK cascade due to coexistence of processive and distributive phosphorylation mechanisms.

    PubMed

    Sun, Jianqiang; Yi, Ming; Yang, Lijian; Wei, Wenbin; Ding, Yiming; Jia, Ya

    2014-03-01

    The processive phosphorylation mechanism becomes important when there is macromolecular crowding in the cytoplasm. Integrating the processive phosphorylation mechanism with the traditional distributive one, we propose a mixed dual-site phosphorylation (MDP) mechanism in a single-layer phosphorylation cycle. Further, we build a degree model by applying the MDP mechanism to a three-layer mitogen-activated protein kinase (MAPK) cascade. By bifurcation analysis, our study suggests that the crowded-environment-induced pseudoprocessive mechanism can qualitatively change the response of this biological network. By adjusting the degree of processivity in our model, we find that the MAPK cascade is able to switch between the ultrasensitivity, bistability, and oscillatory dynamical states. Sensitivity analysis shows that the theoretical results remain unchanged within a reasonably chosen variation of parameter perturbation. By scaling the reaction rates and also introducing new connections into the kinetic scheme, we further construct a proportion model of the MAPK cascade to validate our findings. Finally, it is illustrated that the spatial propagation of the activated MAPK signal can be improved (or attenuated) by increasing the degree of processivity of kinase (or phosphatase). Our research implies that the MDP mechanism makes the MAPK cascade become a flexible signal module, and the coexistence of processive and distributive phosphorylation mechanisms enhances the tunability of the MAPK cascade. PMID:24606945

  18. Trapping Poly(ADP-Ribose) Polymerase.

    PubMed

    Shen, Yuqiao; Aoyagi-Scharber, Mika; Wang, Bing

    2015-06-01

    Recent findings indicate that a major mechanism by which poly(ADP-ribose) polymerase (PARP) inhibitors kill cancer cells is by trapping PARP1 and PARP2 to the sites of DNA damage. The PARP enzyme-inhibitor complex "locks" onto damaged DNA and prevents DNA repair, replication, and transcription, leading to cell death. Several clinical-stage PARP inhibitors, including veliparib, rucaparib, olaparib, niraparib, and talazoparib, have been evaluated for their PARP-trapping activity. Although they display similar capacity to inhibit PARP catalytic activity, their relative abilities to trap PARP differ by several orders of magnitude, with the ability to trap PARP closely correlating with each drug's ability to kill cancer cells. In this article, we review the available data on molecular interactions between these clinical-stage PARP inhibitors and PARP proteins, and discuss how their biologic differences might be explained by the trapping mechanism. We also discuss how to use the PARP-trapping mechanism to guide the development of PARP inhibitors as a new class of cancer therapy, both for single-agent and combination treatments. PMID:25758918

  19. Correlation between surface topography and tribological mechanisms of the belt-finishing process using multiscale finishing process signature

    NASA Astrophysics Data System (ADS)

    Mezghani, Sabeur; Mansori, Mohamed El; Massaq, Abdellah; Ghidossi, Patrick

    2008-10-01

    In practice, two surfaces statically equivalent can be issued from two different manufacturing processes (grinding, belt finishing, honing, …) or obtained using different working process variables (abrasives grits size, contact pressure, …). The common tools and different norms used for industrial surface characterization (ISO 4288, ISO 12085, …) have the main limit of discriminating them through their process signatures. This Note introduces a multiscale decomposition method of the surface topography based on continuous wavelets transform. This approach allows the determination of the multi-scale transfer function of the morphological modification on the surface topography after a finishing process. This technique has been successfully applied to discriminate two surfaces obtained by the belt-finishing process. Moreover, it makes it possible to connect the surface topography modification to the physical and tribological mechanisms of the process (ploughing, cutting, …). To cite this article: S. Mezghani et al., C. R. Mecanique 336 (2008).

  20. 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.

  1. Direct relationship between trapped magnetic flux characteristics and percolation transition temperature in a practical sized bulk high-temperature superconductor

    NASA Astrophysics Data System (ADS)

    Ogama, Y.; Nakamura, T.

    2006-07-01

    The trapped magnetic flux characteristics of a Gd-system bulk high-Tc superconductor (HTS) near the so-called percolation transition temperature was investigated experimentally. The percolation transition temperature was directly determined from the temperature dependence of the E-J characteristics with a bar-shaped HTS. Next, the disc-shaped bulk HTS sample was magnetized by means of a field-cooling process, and then the decay of the trapped magnetic flux density was monitored for 30 min after the exciting current of the electromagnet was cut off. It was shown that the decay rate of trapped magnetic flux changed considerably around the percolation transition temperature. Furthermore, the trapped flux showed stepwise decay, and these phenomena could explain the percolation mechanism of the depinning process. From our study, the percolation temperature may be utilized for the limit parameter in order to design application systems with a practical sized bulk HTS.

  2. 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

  3. Optical trapping of nanoparticles.

    PubMed

    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 beam. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles. 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 sec, which has serious implications for biological matter. A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime. 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 enhancement. 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 spheres and 3.4 nm hydrodynamic radius bovine serum albumin proteins. 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

  4. 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.

  5. 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. PMID:26155111

  6. Optically programmable excitonic traps

    PubMed Central

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

    2013-01-01

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

  7. Nonlinear integrable ion traps

    SciTech Connect

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

    2011-10-01

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

  8. 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; Krten, Andreas; Hlzer, Jasper; Mitschke, Stefan; Mhlberger, Fabian; Sklorz, Martin; Wieser, Jochen; Ulrich, Andreas; Ptz, 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

  9. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-Alaskan mechanized bottom fish processing subcategory. 408.220 Section 408.220 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory. The provisions...

  10. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-Alaskan mechanized bottom fish processing subcategory. 408.220 Section 408.220 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory. The provisions...

  11. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-Alaskan mechanized bottom fish processing subcategory. 408.220 Section 408.220 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory. The provisions...

  12. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-Alaskan mechanized bottom fish processing subcategory. 408.220 Section 408.220 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory. The provisions...

  13. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-Alaskan mechanized bottom fish processing subcategory. 408.220 Section 408.220 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory. The provisions...

  14. Capture and identification of the volatile components in crude and processed herbal medicines through on-line purge and trap technique coupled with GC × GC-TOF MS.

    PubMed

    Cao, Gang; Xu, Zhiwei; Wu, Xin; Li, Qingli; Chen, Xiaocheng

    2014-01-01

    This work aimed to investigate the volatile components in crude and processed herbal medicines (HMs). Using Atractylodis Macrocephalae Rhizoma (AMR) as a model HM, the volatile components were captured through on-line purge and trap technique and identified by using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOF MS) system. A total of 224 and 171 volatile compounds were identified in crude and processed AMR samples, respectively. After frying with honey-bran, 52 compounds which were found in crude AMR samples disappeared in processed AMR samples, and 15 compounds were newly generated in processed AMR. The established method can be applied in different research areas such as HM and food processing. PMID:24960332

  15. 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.

  16. Trap diversity and evolution in the family Droseraceae.

    PubMed

    Poppinga, Simon; Hartmeyer, Siegfried R H; Masselter, Tom; Hartmeyer, Irmgard; Speck, Thomas

    2013-07-01

    We review trapping mechanisms in the carnivorous flowering plant family Droseraceae (order Caryophyllales). Its members are generally known to attract, capture, retain and digest prey animals (mainly arthropods) with active snap-traps (Aldrovanda, Dionaea) or with active sticky flypaper traps (Drosera) and to absorb the resulting nutrients. Recent investigations revealed how the snap-traps of Aldrovanda vesiculosa (waterwheel plant) and Dionaea muscipula (Venus' flytrap) work mechanically and how these apparently similar devices differ as to their functional morphology and shutting mechanics. The Sundews (Drosera spp.) are generally known to possess leaves covered with glue-tentacles that both can bend toward and around stuck prey. Recently, it was shown that there exists in this genus a higher diversity of different tentacle types and trap configurations than previously known which presumably reflect adaptations to different prey spectra. Based on these recent findings, we finally comment on possible ways for intrafamiliar trap evolution. PMID:23603942

  17. Trap diversity and evolution in the family Droseraceae

    PubMed Central

    Poppinga, Simon; Hartmeyer, Siegfried R.H.; Masselter, Tom; Hartmeyer, Irmgard; Speck, Thomas

    2013-01-01

    We review trapping mechanisms in the carnivorous flowering plant family Droseraceae (order Caryophyllales). Its members are generally known to attract, capture, retain and digest prey animals (mainly arthropods) with active snap-traps (Aldrovanda, Dionaea) or with active sticky flypaper traps (Drosera) and to absorb the resulting nutrients. Recent investigations revealed how the snap-traps of Aldrovanda vesiculosa (waterwheel plant) and Dionaea muscipula (Venus flytrap) work mechanically and how these apparently similar devices differ as to their functional morphology and shutting mechanics. The Sundews (Drosera spp.) are generally known to possess leaves covered with glue-tentacles that both can bend toward and around stuck prey. Recently, it was shown that there exists in this genus a higher diversity of different tentacle types and trap configurations than previously known which presumably reflect adaptations to different prey spectra. Based on these recent findings, we finally comment on possible ways for intrafamiliar trap evolution. PMID:23603942

  18. 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

  19. 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…

  20. Cooperative optical trapping in asymmetric plasmon nanocavity arrays.

    PubMed

    Guo, Ling; Sun, Zhijun

    2015-11-30

    We propose a scheme using cooperative interaction of antiphase resonance modes to enhance optical trapping in plasmonic nanostructures. This is implemented with a subwavelength array of asymmetric binary nanogrooves (e.g. different depths) in metal. When damping and inter-coupling of antiphase fields in the nanogrooves are mediated satisfying a critical condition, light can be cooperatively trapped in the nanogrooves, demonstrating perfect absorption at nearly the intrinsic resonance frequency of the deeper nanogrooves. A harmonic oscillator model is developed to interpret the cooperative interaction processes. The phenomenon has been also implemented in asymmetric ternary nanogroove arrays. In terms of compositions and intra-coupling mechanisms, the asymmetric binary/ternary plasmonic nanostructure arrays are crystalline molecular-metamaterials, analogous to electronic crystals composed of covalence-bond molecules. PMID:26698759

  1. Quantum-enhanced deliberation of learning agents using trapped ions

    NASA Astrophysics Data System (ADS)

    Dunjko, V.; Friis, N.; Briegel, H. J.

    2015-02-01

    A scheme that successfully employs quantum mechanics in the design of autonomous learning agents has recently been reported in the context of the projective simulation (PS) model for artificial intelligence. In that approach, the key feature of a PS agent, a specific type of memory which is explored via random walks, was shown to be amenable to quantization, allowing for a speed-up. In this work we propose an implementation of such classical and quantum agents in systems of trapped ions. We employ a generic construction by which the classical agents are upgraded to their quantum counterparts by a nested process of adding coherent control, and we outline how this construction can be realized in ion traps. Our results provide a flexible modular architecture for the design of PS agents. Furthermore, we present numerical simulations of simple PS agents which analyze the robustness of our proposal under certain noise models.

  2. Production and Trapping of Ultracold Polar Molecules

    SciTech Connect

    David, DeMille

    2015-04-21

    We report a set of experiments aimed at the production and trapping of ultracold polar molecules. We begin with samples of laser-cooled and trapped Rb and Cs atoms, and bind them together to form polar RbCs molecules. The binding is accomplished via photoassociation, which uses a laser to catalyze the sticking process. We report results from investigation of a new pathway for photoassociation that can produce molecules in their absolute ground state of vibrational and rotational motion. We also report preliminary observations of collisions between these ground-state molecules and co-trapped atoms.

  3. The Effect of Thermo-mechanical Processing on the Mechanical Properties of Molybdenum-2 Volume%Lanthana

    SciTech Connect

    A.J. Mueller; R.W. Buckman,Jr.; A.J. Shields,Jr

    2001-03-14

    Variations in oxide species and consolidation method have been shown to have a significant effect on the mechanical properties of oxide dispersion strengthened (ODS) molybdenum material. The mechanical behavior of molybdenum - 2 Volume % La[sub]2O[sub]3 mill product forms, produced by a wet doping process, were characterized over the temperature range of -150 degrees C to 1800 degrees C. The various mill product forms evaluated ranged from thin sheet stock to bar stock. Tensile properties of the material in the various product forms were not significantly affected by the vast difference in total cold work. Creep properties, however, were sensitive to the total amount of cold work as well as the starting microstructure. Stress-relieved material had superior creep rupture properties to recrystallized material at 1200 degrees C, while at 1500 degrees C and above the opposite was observed. Thus it is necessary to match the appropriate thermo-mechanical processing and microstructure of molybdenum - 2 volume % LA[sub]2O[sub]3 to the demands of the application being considered.

  4. Microkinetic modeling of lean NOx trap chemistry

    SciTech Connect

    Larson, Rich; Chakravathy, Kalyana; Pihl, Josh A; Daw, C Stuart

    2012-01-01

    A microkinetic chemical reaction mechanism capable of describing both the storage and regeneration processes in a fully formulated lean NO{sub x} trap is presented. The mechanism includes steps occurring on the precious metal, NO{sub x} storage, and oxygen storage sites of the catalyst. The complete reaction set is used with a transient plug flow reactor code (including boundary layer mass transfer) to simulate not only storage/regeneration cycles with a CO/H{sub 2} reductant, but also steady flow temperature sweep experiments that were previously analyzed with just a precious metal mechanism and a simpler steady state code. The results imply that NO{sub x} storage was not negligible during some of the temperature ramps, necessitating a re-evaluation of the precious metal kinetic parameters. The parameters for the entire mechanism are inferred by finding the best overall fit to the complete set of experiments. Rigorous thermodynamic consistency is enforced for parallel reaction pathways and with respect to known data for all gas phase species. It is found that nearly all of the basic experimental observations can be reproduced with the transient simulations.

  5. Microstructures and mechanical properties of Ti5553 alloy processed by high-pressure torsion

    NASA Astrophysics Data System (ADS)

    Jiang, B. Z.; Emura, S.; Tsuchiya, K.

    2014-08-01

    In the present research, the effects of high-pressure torsion (HPT) processing on the microstructure and mechanical properties of Ti-5Al-5Mo-5V-3Cr (Ti5553) alloy were studied. HPT processing produced a white etching layer (WEL) in the middle section of the cross-section and numerous shear bands in the surface region of the cross-section. And the thickness of the WEL increased with increasing the HPT revolutions. TEM observation of the WEL revealed an ultrafine-grained structure with high degree of lattice distortions. The mechanical properties measurements showed that the hardness and ultimate tensile strength increased by HPT processing, accompanied with a decrease in the elongation to failure. It is considered that the mechanical properties of HPT processed Ti5553 alloy are mostly dominated by the shear banded region and the WEL where have the finest grain size and high density of dislocations.

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

    SciTech Connect

    Del Cul, G.D.; Toth, L.M.

    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.

  7. 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

  8. Modeling of the effect of intentionally introduced traps on hole transport in single-crystal rubrene

    NASA Astrophysics Data System (ADS)

    Dacua, Javier; Desai, Amit; Xie, Wei; Salleo, Alberto

    2014-06-01

    Defects have been intentionally introduced in a rubrene single crystal by means of two different mechanisms: ultraviolet ozone (UVO) exposure and x-ray irradiation. A complete drift-diffusion model based on the mobility edge (ME) concept, which takes into account asymmetries and nonuniformities in the semiconductor, is used to estimate the energetic and spatial distribution of trap states. The trap distribution for pristine devices can be decomposed into two well defined regions: a shallow region ascribed to structural disorder and a deeper region ascribed to defects. UVO and x ray increase the hole trap concentration in the semiconductor with different energetic and spatial signatures. The former creates traps near the top surface in the 0.3-0.4 eV region, while the latter induces a wider distribution of traps extending from the band edge with a spatial distribution that peaks near the top and bottom interfaces. In addition to inducing hole trap states in the transport gap, both processes are shown to reduce the mobility with respect to a pristine crystal.

  9. 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.

    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.

  10. 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

  11. The magnetism of a glacial aeolianite sequence from Lanzarote (Canary Islands): coupling between luvic calcisol formation and Saharan dust trapping processes during wet deposition events off northwestern Sahara

    NASA Astrophysics Data System (ADS)

    Williamson, David; Jackson, Mike; Banerjee, Subir K.; Petit-Maire, Nicole

    2004-06-01

    In order to better document the climatic origin of pedogenized loess deposits west of Sahara, rock-magnetic measurements were performed on a Last Glacial coastal sand sequence from La Mala (LM) quarry (Lanzarote, Canary Islands) containing six interbedded loess-palaeosol units. Hysteresis and susceptibility data point to a coarse-grained magnetic enhancement in the coastal sand, which contrasts with the superparamagnetic (SP) to pseudo-single domain (PSD) behaviour of the Saharan loess and palaeosol. High- and low-temperature experiments show that oxidized titanomagnetite contributions dominate in the sand, while fine-grained (SP to PSD) iron oxidation products such as maghemite and goethite are evidenced in the Saharan loess/palaeosol units. At room temperature, the detrital PSD-multidomain titanomagnetite contribution of local origin is tentatively estimated from the AC-field dependence of magnetic susceptibility. Surface oxidation of detrital spinel grains and authigenesis of fine-grained iron oxides (including SP goethite) are proposed to explain the magnetic properties of the primarily fine, Saharan-dust-bearing material. The dry, local climate of the present-day and Late Holocene means that loess deposits are not preserved. The six pedogenized loess units, however, point to dust trapping under semi-arid, wetter conditions, probably illustrating periods of reduced latitudinal temperature gradients and climate variability of the North Atlantic climate, respectively. These findings suggest that both the Canary palaeosol and its content of (ultra)fine iron oxide might be constrained by (wet) deposition and trapping of fine Saharan dust.

  12. Mechanisms of food processing and storage-related stress tolerance in Clostridium botulinum.

    PubMed

    Dahlsten, Elias; Lindström, Miia; Korkeala, Hannu

    2015-05-01

    Vegetative cultures of Clostridium botulinum produce the extremely potent botulinum neurotoxin, and may jeopardize the safety of foods unless sufficient measures to prevent growth are applied. Minimal food processing relies on combinations of mild treatments, primarily to avoid deterioration of the sensory qualities of the food. Tolerance of C. botulinum to minimal food processing is well characterized. However, data on effects of successive treatments on robustness towards further processing is lacking. Developments in genetic manipulation tools and the availability of annotated genomes have allowed identification of genetic mechanisms involved in stress tolerance of C. botulinum. Most studies focused on low temperature, and the importance of various regulatory mechanisms in cold tolerance of C. botulinum has been demonstrated. Furthermore, novel roles in cold tolerance were shown for metabolic pathways under the control of these regulators. A role for secondary oxidative stress in tolerance to extreme temperatures has been proposed. Additionally, genetic mechanisms related to tolerance to heat, low pH, and high salinity have been characterized. Data on genetic stress-related mechanisms of psychrotrophic Group II C. botulinum strains are scarce; these mechanisms are of interest for food safety research and should thus be investigated. This minireview encompasses the importance of C. botulinum as a food safety hazard and its central physiological characteristics related to food-processing and storage-related stress. Special attention is given to recent findings considering genetic mechanisms C. botulinum utilizes in detecting and countering these adverse conditions. PMID:25303833

  13. 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.

  14. Atom trap loss, elastic collisions, and technology

    NASA Astrophysics Data System (ADS)

    Booth, James

    2012-10-01

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

  15. Stratigraphic traps 2

    SciTech Connect

    Not Available

    1991-01-01

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

  16. Radio Frequency Generation of an Electron Plasma in a Malmberg-Penning Trap

    SciTech Connect

    Paroli, B.; De Luca, F.; Pozzoli, R.; Rome, M.; Maero, G.

    2010-06-16

    The generation of an electron plasma via low-power Radio Frequency (RF) excitation has been observed in the Malmberg-Penning trap ELTRAP under ultra-high vacuum conditions. The process is sensitive to the RF parameters as well as to the trapping length. The electron heating mechanism necessary to reach the ionization energy of the residual gas has been modeled with the use of a simple one-dimensional iterative map, whose properties show a behavior similar to that of the Fermi acceleration map.

  17. IMaX opto-mechanical integration: the AIV process for a magnetograph

    NASA Astrophysics Data System (ADS)

    Ramos Zapata, Gonzalo; Gonzlez Fernandez, Luis Miguel; Snchez Rodrguez, Antonio; Pastor Santos, Carmen; lvarez-Herrero, Alberto

    2008-07-01

    IMaX current status is reported on. IMaX, the Imaging Magnetograph eXperiment developed for a Spanish consortium for the SUNRISE Mission, is a payload that will work simultaneously as a high sensitivity polarimeter, a high resolving spectral power, and a near diffraction limited imager. Once every mechanical element has been purchased, the assembly, integration, alignment and verification processes (AIV process) has been carried out successfully. After a brief description of the IMaX opto-mechanical elements that have been received, the integration sequence as well as the main results obtained during the AIV process are presented. Basically, AIV process consists on the opto-mechanical components assembly on the Optical Bench (OB), the optical elements assembly on the previously integrated optomechanics, the alignment and orientation of the opto-mechanical components, and the two-channels quality evaluation that allows to leave the opto-mechanical components ready for the cameras integration and IMaX performance tests characterization. Actually, the most relevant results related to the AIV process as well as the IMaX performance firsts tests are presented.

  18. Single trap dynamics in electrolyte-gated Si-nanowire field effect transistors

    SciTech Connect

    Pud, S.; Li, J.; Offenhusser, A.; Vitusevich, S. A.; Gasparyan, F.; Petrychuk, M.

    2014-06-21

    Liquid-gated silicon nanowire (NW) field effect transistors (FETs) are fabricated and their transport and dynamic properties are investigated experimentally and theoretically. Random telegraph signal (RTS) fluctuations were registered in the nanolength channel FETs and used for the experimental and theoretical analysis of transport properties. The drain current and the carrier interaction processes with a single trap are analyzed using a quantum-mechanical evaluation of carrier distribution in the channel and also a classical evaluation. Both approaches are applied to treat the experimental data and to define an appropriate solution for describing the drain current behavior influenced by single trap resulting in RTS fluctuations in the Si NW FETs. It is shown that quantization and tunneling effects explain the behavior of the electron capture time on the single trap. Based on the experimental data, parameters of the single trap were determined. The trap is located at a distance of about 2?nm from the interface Si/SiO{sub 2} and has a repulsive character. The theory of dynamic processes in liquid-gated Si NW FET put forward here is in good agreement with experimental observations of transport in the structures and highlights the importance of quantization in carrier distribution for analyzing dynamic processes in the nanostructures.

  19. Current leakage relaxation and charge trapping in ultra-porous low-k materials

    SciTech Connect

    Borja, Juan; Plawsky, Joel L. Gill, William N.; Lu, T.-M.; Bakhru, Hassaram

    2014-02-28

    Time dependent dielectric failure has become a pivotal aspect of interconnect design as industry pursues integration of sub-22?nm process-technology nodes. Literature has provided key information about the role played by individual species such as electrons, holes, ions, and neutral impurity atoms. However, no mechanism has been shown to describe how such species interact and influence failure. Current leakage relaxation in low-k dielectrics was studied using bipolar field experiments to gain insight into how charge carrier flow becomes impeded by defects within the dielectric matrix. Leakage current decay was correlated to injection and trapping of electrons. We show that current relaxation upon inversion of the applied field can be described by the stretched exponential function. The kinetics of charge trapping events are consistent with a time-dependent reaction rate constant, k=k{sub 0}?(t+1){sup ??1}, where 0?trapping reactions in amorphous solids by W. H. Hamill and K. Funabashi, Phys. Rev. B 16, 55235527 (1977). We explain the relaxation process in charge trapping events by introducing a nonlinear charge trapping model. This model provides a description on the manner in which the transport of mobile defects affects the long-tail current relaxation processes in low-k films.

  20. Particle acceleration in collapsing magnetic traps

    NASA Astrophysics Data System (ADS)

    Bogachev, Sergey

    Collapsing magnetic traps were introduced to the solar physics by B.V.Somov and T.Kosugi in 1997 with the aim to explain an appearance and main properties of the hard X-ray (HXR) loop-top source in solar flares. The plasma density in the place where the coronal HXR emission forms is usually not enough to explain the origin of the emission in the framework of the so-called thick target model. The trapping of the emitting electrons in the corona can partially solve this problem. The negative impact on the emission due to low density of the surrounding plasma can be compensated in this case by the increase of the particle lifetime in the corona. Collapsing traps are formed from the reconnecting magnetic lines during the impulsive phase of a flare and, in general, can be introduced to the standard model of a flare without any specific assumptions. Due to the motion of the reconnecting magnetic lines, a collapsing trap can not only capture but also accelerate the trapped particles by Fermi and betatron acceleration mechanisms. Taking this into account, the collapsing traps are now considered both as a mechanism to produce an intensive HXR emission in the corona and as an effective way for the acceleration of charged particles in flares. In this talk we try to summarize the current knowledge on the physics of the collapsing magnetic traps: their main properties, the influence on the energy of trapped particles and the characteristics of observed HXR emission. We believe that in addition to its theoretical value, this review may be useful in anticipation of new experimental data from the hard X-ray imagers STIX on Solar Orbiter and SORENTO on Interhelioprobe.