Science.gov

Sample records for processes trapping mechanisms

  1. Trapped Atomic Ions and Quantum Information Processing

    SciTech Connect

    Wineland, D. J.; Leibfried, D.; Bergquist, J. C.; Blakestad, R. B.; Bollinger, J. J.; Britton, J.; Chiaverini, J.; Epstein, R. J.; Hume, D. B.; Itano, W. M.; Jost, J. D.; Koelemeij, J. C. J.; Langer, C.; Ozeri, R.; Reichle, R.; Rosenband, T.; Schaetz, T.; Schmidt, P. O.; Seidelin, S.; Shiga, N.

    2006-11-07

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

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

    SciTech Connect

    Liu, Yanhong; Gao, Ping; Li, La; Peng, Wei; 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.

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

    NASA Astrophysics Data System (ADS)

    Kim, Yeong E.; Zubarev, Alexander L.

    2006-02-01

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

  4. 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

  5. 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

  6. Molten Hydroxide Trapping Process for Radioiodine

    SciTech Connect

    Trowbridge, L.D.

    2003-01-28

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

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

    PubMed

    Gulde, S; Häffner, 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

  8. Quantum information processing with trapped Ca+ ions

    NASA Astrophysics Data System (ADS)

    Gulde, S.; Häffner, 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.

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

    SciTech Connect

    Abe, K.; Hasegawa, T.

    2010-03-15

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

  10. Quantum information processing with trapped ions

    E-print Network

    Hensinger, Winfried

    /magnetic fields Wolfgang Paul Paul trap 1956 AC/DC electric fields #12;Pseudopotential approximation assume field and laser cooled 9Be+ ions in a Paul-trap at NIST 1980/1981 single trapped and laser cooled atomic ions surface electrode trap x y #12;time dependent potential (Mathieu equation) The linear Paul trap radial

  11. TRANSIENT QUANTUM MECHANICAL PROCESSES

    SciTech Connect

    L. COLLINS; J. KRESS; R. WALKER

    1999-07-01

    Our principal objective has centered on the development of sophisticated computational techniques to solve the time-dependent Schroedinger equation that governs the evolution of quantum mechanical systems. We have perfected two complementary methods, discrete variable representation and real space product formula, that show great promise in solving these complicated temporal problems. We have applied these methods to the interaction of laser light with molecules with the intent of not only investigating the basic mechanisms but also devising schemes for actually controlling the outcome of microscopic processes. Lasers now exist that produce pulses of such short duration as to probe a molecular process many times within its characteristic period--allowing the actual observation of an evolving quantum mechanical system. We have studied the potassium dimer as an example and found agreement with experimental changes in the intermediate state populations as a function of laser frequency--a simple control prescription. We have also employed elaborate quantum chemistry programs to improve the accuracy of basic input such as bound-bound and bound-free coupling moments. These techniques have far-ranging applicability; for example, to trapped quantum systems at very low temperatures such as Bose-Einstein condensates.

  12. 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

  13. 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.

  14. The catalytic mechanism of diarylamine radical-trapping antioxidants.

    PubMed

    Haidasz, Evan A; Shah, Ron; Pratt, Derek A

    2014-11-26

    Diarylamine radical-trapping antioxidants are important industrial additives, finding widespread use in petroleum-derived products. They are uniquely effective at elevated temperatures due to their ability to trap multiple radicals per molecule of diarylamine. Herein we report the results of computational and experimental studies designed to elucidate the mechanism of this remarkable activity. We find that the key step in the proposed catalytic cycle-decomposition of the alkoxyamine derived from capture of a substrate-derived alkyl radical with a diarylamine-derived nitroxide-proceeds by different mechanisms depending on the structure of both the substrate and the diarylamine. N,N-Diarylalkoxyamines derived from saturated substrates and diphenylamines decompose by N-O homolysis followed by disproportionation. Alternatively, those derived from unsaturated substrates and diphenylamines, or saturated substrates and N-phenyl-?-naphthylamine, decompose by an unprecedented concerted retro-carbonyl-ene reaction. The alkoxyamines that decompose by the concerted process inhibit hexadecane autoxidations at 160 °C to the same extent as the corresponding diarylamine, whereas those alkoxyamines that decompose by the N-O homolysis/disproportionation pathway are much less effective. This suggests that the competing cage escape of the alkoxyl radicals following N-O homolysis leads to significantly less effective regeneration of diarylamines and implies that the catalytic efficiency of diarylamine antioxidants is substrate-dependent. The results presented here have significant implications in the future design of antioxidant additives: diarylamines designed to yield intermediate alkoxyamines that undergo the retro-carbonyl-ene reaction are likely to be much more effective than existing compounds and will display catalytic radical-trapping activities at lower temperatures due to lower barriers to regeneration. PMID:25354493

  15. 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

  16. Ion-trap quantum information processing: experimental status

    E-print Network

    D. Kielpinski

    2008-05-19

    Atomic ions trapped in ultra-high vacuum form an especially well-understood and useful physical system for quantum information processing. They provide excellent shielding of quantum information from environmental noise, while strong, well-controlled laser interactions readily provide quantum logic gates. A number of basic quantum information protocols have been demonstrated with trapped ions. Much current work aims at the construction of large-scale ion-trap quantum computers using complex microfabricated trap arrays. Several groups are also actively pursuing quantum interfacing of trapped ions with photons.

  17. 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.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

    Çelik-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.

  20. Process-dependent residual trapping of CO2 in sandstone

    NASA Astrophysics Data System (ADS)

    Zuo, Lin; Benson, Sally M.

    2014-04-01

    This paper demonstrates that the nature and extent of residual CO2 trapping depend on the process by which the CO2 phase is introduced into the rock. We compare residual trapping of CO2 in Berea Sandstone by imbibing water into a core containing either exsolved CO2 or CO2 introduced by drainage. X-ray computed tomography measurements are used to map the spatial distribution of CO2 preimbibition and postimbibition. Unlike during drainage where the CO2 distribution is strongly influenced by the heterogeneity of the rock, the distribution of exsolved CO2 is comparatively uniform. Postimbibition, the CO2 distribution retained the essential features for both the exsolved and drainage cases, but twice as much residual trapping is observed for exsolved CO2 even with similar preimbibition gas saturations. Residually trapped exsolved gas also disproportionately reduced water relative permeability. Development of process-dependent parameterization will help better manage subsurface flow processes and unlock benefits from gas exsolution.

  1. 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.

  2. Demonstration of a Scalable, Multiplexed Ion Trap for Quantum Information Processing

    E-print Network

    Leibrandt, David R.

    A scalable, multiplexed ion trap for quantum information processing is fabricated and tested. The trap design and fabrication process are optimized for scalability to small trap size and large numbers of interconnected ...

  3. Quantum information processing with trapped electrons and superconducting electronics

    E-print Network

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

    2013-04-17

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

  4. Monolithic Microfabricated Symmetric Ion Trap for Quantum Information Processing

    E-print Network

    Fayaz Shaikh; Arkadas Ozakin; Jason M. Amini; Harley Hayden; C. -S. Pai; Curtis Volin; Douglas R. Denison; Daniel Faircloth; Alexa W. Harter; Richart E. Slusher

    2011-05-24

    We describe a novel monolithic ion trap that combines the flexibility and scalability of silicon microfabrication technologies with the superior trapping characteristics of traditional four-rod Paul traps. The performace of the proposed microfabricated trap approaches that of the macroscopic structures. The fabrication process creates an angled through-chip slot which allows backside ion loading and through-laser access while avoiding surface light scattering and dielectric charging. The trap geometry and dimensions are optimized for confining long ion chains with equal ion spacing [G.-D. Lin, et al., Europhys. Lett. 86, 60004 (2009)]. Control potentials have been derived to produce linear, equally spaced ion chains of up to 50 ions spaced at 10 um. With the deep trapping depths achievable in this design, we expect that these chains will be sufficiently long-lived to be used in quantum simulations of magnetic systems [E.E. Edwards, et al., Phys. Rev. B 82, 060412(R) (2010)]. The trap is currently being fabricated at Georgia Tech using VLSI techniques.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  6. Grover-like search via Frenkel exciton trapping mechanism

    E-print Network

    A. Thilagam

    2010-02-22

    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 which 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 analysis of quantum search to a fluctuating long-range interacting cycle (LRIC) graph lattice system.

  7. Grover-like search via Frenkel exciton trapping mechanism

    E-print Network

    Thilagam, A

    2010-01-01

    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 which 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 analysis of quantum search to a fluctuating long-range interacting cycle (LRIC) graph lattice system.

  8. Ultrahigh-Q mechanical oscillators through optical trapping

    NASA Astrophysics Data System (ADS)

    Chang, D. E.; Ni, K.-K.; Painter, O.; Kimble, H. J.

    2012-04-01

    Rapid advances are being made toward optically cooling a single mode of a micro-mechanical system to its quantum ground state and observing the 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, Qmfm ? kBTbath/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 one to obtain unprecedented Q-frequency products. The technique is based on the use of optical forces to ‘trap’ and stiffen the motion of a tethered mechanical structure, thereby freeing the resulting mechanical frequencies and decoherence rates from the underlying material properties.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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].

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

    E-print Network

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

    2006-07-07

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

  15. 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.

  16. 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).

  17. Experimental methods by optical trapping for investigation of leukocyte cell rolling mechanics

    E-print Network

    Navarro, Sergio Michael

    2008-01-01

    This thesis focuses on the design and implementation of a range of experimental methods by optical trapping in order to investigate the mechanical behavior of the leukocyte cell membrane as it undergoes cell rolling. ...

  18. Adiabatic Processes Realized with a Trapped Brownian Particle

    NASA Astrophysics Data System (ADS)

    Martínez, Ignacio A.; Roldán, Édgar; Dinis, Luis; Petrov, Dmitri; Rica, Raúl 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.

  19. 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

  20. 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

  1. 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

  2. Nonvolatile multilevel data storage memory device from controlled ambipolar charge trapping mechanism

    PubMed Central

    Zhou, Ye; Han, Su-Ting; Sonar, Prashant; Roy, V. A. L.

    2013-01-01

    The capability of storing multi-bit information is one of the most important challenges in memory technologies. An ambipolar polymer which intrinsically has the ability to transport electrons and holes as a semiconducting layer provides an opportunity for the charge trapping layer to trap both electrons and holes efficiently. Here, we achieved large memory window and distinct multilevel data storage by utilizing the phenomena of ambipolar charge trapping mechanism. As fabricated flexible memory devices display five well-defined data levels with good endurance and retention properties showing potential application in printed electronics. PMID:23900459

  3. Optoelectronic neural dendritic tree processing with electron-trapping materials

    NASA Astrophysics Data System (ADS)

    Wen, Z.; Baek, A.; Farhat, N. H.

    1995-03-01

    We show that under simultaneous illumination of pulsed blue light and constant IR light the dynamic responses of electron-trapping materials could be employed to implement optically controlled neural dendritic responses. The importance of neurocomputing with biology-oriented spiking neurons and the role played by dendritic trees are discussed. Computer simulations of dendritic responses in biological neuron and experimental results of electron-trapping material dynamics are presented. These results show that electron-trapping materials are well suited for implementing optically controlled dendritic responses for use in large-scale biology-oriented optoelectronic spiking neural networks.

  4. 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.

  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 maneuvers—involving what is thought, how it is thought, and how it is organized—may generate defensive states. The theories are not contradictory, but they are focused on different levels of observation; it is useful to compare how these classifications are applied to specific case material. PMID:22700114

  6. Dynamical traps in Wang-Landau sampling of continuous systems: Mechanism and solution

    NASA Astrophysics Data System (ADS)

    Koh, Yang Wei; Sim, Adelene Y. L.; Lee, Hwee Kuan

    2015-08-01

    We study the mechanism behind dynamical trappings experienced during Wang-Landau sampling of continuous systems reported by several authors. Trapping is caused by the random walker coming close to a local energy extremum, although the mechanism is different from that of the critical slowing-down encountered in conventional molecular dynamics or Monte Carlo simulations. When trapped, the random walker misses the entire or even several stages of Wang-Landau modification factor reduction, leading to inadequate sampling of the configuration space and a rough density of states, even though the modification factor has been reduced to very small values. Trapping is dependent on specific systems, the choice of energy bins, and the Monte Carlo step size, making it highly unpredictable. A general, simple, and effective solution is proposed where the configurations of multiple parallel Wang-Landau trajectories are interswapped to prevent trapping. We also explain why swapping frees the random walker from such traps. The efficacy of the proposed algorithm is demonstrated.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  8. 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.

  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 coherence and population trapping in three-photon processes

    E-print Network

    Caroline Champenois; Giovanna Morigi; Juergen Eschner

    2006-09-22

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

  11. Breathing-trap mechanism for encapsulation of atomic hydrogen in C60

    E-print Network

    Allen, Roland E.

    temperature and high pressure treatments [7], atomic collisions in beams [8], and ion implantation [9]. HereBreathing-trap mechanism for encapsulation of atomic hydrogen in C60 Zhongqu Longa , Xiang Zhoua vaporization [2, 3]. A wide variety of atoms and molecules have now been successfully encapsulated in the C60

  12. Actin filament mechanics in the laser trap D. E. DUPUIS1 , 2

    E-print Network

    Guilford, William

    Actin filament mechanics in the laser trap D. E. DUPUIS1 , 2 , W. H. GUILFORD1 , J. WU3 and D. M properties of actin filaments. One such property is resistance to bending (flexural rigidity, EI). To estimate EI, we attached the ends of fluorescently labelled actin filaments to two microsphere `handles

  13. 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...

  14. Nonlinearity from quantum mechanics: Dynamically unstable Bose-Einstein condensate in a double-well trap

    E-print Network

    Javanainen, Juha

    2010-01-01

    We study theoretically an atomic Bose-Einstein condensate in a double-well trap both quantum mechanically and classically under conditions such that in the classical model an unstable equilibrium dissolves into large-scale oscillations of the atoms between the potential wells. Quantum mechanics alone does not exhibit such nonlinear dynamics, but measurements of the atom numbers in the potential wells may nevertheless cause the condensate to behave essentially classically.

  15. 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.

  16. Chemically assisted mechanical refrigeration process

    DOEpatents

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

    1987-01-01

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

  17. 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.

  18. 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.

  19. Chemically assisted mechanical refrigeration process

    DOEpatents

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

    1987-01-01

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

  20. 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.

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

    NASA Astrophysics Data System (ADS)

    Gulde, S.; Häffner, 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.

  2. 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.

  3. 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.

  4. 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

  5. Department of Mechanical and Process Engineering

    E-print Network

    Daraio, Chiara

    Department of Mechanical and Process Engineering Master in Mechanical Engineering Qualification large international firms in manufacturing, automotive, aerospace, aircraft, and energy industries Profile of MSc ETH in Mechanical Engineering D-MAVT furthers the development of many emerging areas

  6. 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...

  7. 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 4.2±1.5% was observed. The depth of focus for the imaging system was 19.4±2.4?m and the field of view was 140±20?m. Our approach also provides an integrated solution for high-efficiency optical coupling in neutral atom and solid-state QIP architectures.

  8. Supporting Kibble-Zurek Mechanism in Quantum Ising Model through a Trapped Ion

    E-print Network

    Jin-Ming Cui; Yun-Feng Huang; Zhao Wang; Dong-Yang Cao; Jian Wang; Wei-Min Lv; Yong Lu; Le Luo; Adolfo del Campo; Yong-Jian Han; Chuan-Feng Li; Guang-Can Guo

    2015-06-22

    The Kibble-Zurek mechanism is the paradigm to account for the non adiabatic dynamics of a system across a phase transition. Its study in the quantum regime is hindered by the requisite of ground state cooling. We report the experimental quantum simulation of critical dynamics in the transverse-field Ising model by a set of Landau-Zener crossings in pseudo-momentum space, that can be probed with high accuracy using a single trapped ion. Our results support the Kibble-Zurek mechanism in the quantum regime and advance the quantum simulation of critical systems far-away from equilibrium.

  9. 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.

  10. 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

  11. 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

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

    E-print Network

    Poppinga, Simon

    2011-01-01

    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 the first 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 deforma...

  13. Mechanical effects of optical resonators on driven trapped atoms: Ground state cooling in a high finesse cavity

    E-print Network

    Stefano Zippilli; Giovanna Morigi

    2007-03-21

    We investigate theoretically the mechanical effects of light on atoms trapped by an external potential, whose dipole transition couples to the mode of an optical resonator and is driven by a laser. We derive an analytical expression for the quantum center-of-mass dynamics, which is valid in presence of a tight external potential. This equation has broad validity and allows for a transparent interpretation of the individual scattering processes leading to cooling. We show that the dynamics are a competition of the mechanical effects of the cavity and of the laser photons, which may mutually interfere. We focus onto the good-cavity limit and identify novel cooling schemes, which are based on quantum interference effects and lead to efficient ground state cooling in experimentally accessible parameter regimes.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Thilagam, A.

    2010-03-01

    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.

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

    PubMed

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

    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

  17. 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 ?m), 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.

  18. 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

  19. 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.

  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. 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.

  2. 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

  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. 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.

  5. Energy storage and dispersion of surface acoustic waves trapped in a periodic array of mechanical resonators

    NASA Astrophysics Data System (ADS)

    Dühring, Maria B.; Laude, Vincent; Khelif, Abdelkrim

    2009-05-01

    It has been shown previously that surface acoustic waves can be efficiently trapped and slowed by steep ridges on a piezoelectric substrate, giving rise to two families of shear-horizontal and vertically polarized surface waves. The mechanisms of energy storage and dispersion are explored by using the finite element method to model surface acoustic waves generated by high aspect ratio electrodes. A periodic model is proposed including a perfectly matched layer to simulate radiation conditions away from the sources, from which the modal distributions are found. The ratio of the mechanical energy confined to the electrode as compared to the total mechanical energy is calculated and is found to be increasing for increasing aspect ratio and to tend to a definite limit for the two families of surface waves. This observation is in support of the interpretation that high aspect ratio electrodes act as resonators storing mechanical energy. These resonators are evanescently coupled by the surface. The dispersion diagram is presented and shows very low group velocities as the wave vector approaches the limit of the first Brillouin zone.

  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. Quantum control, quantum information processing, and quantum-limited metrology with trapped ions

    E-print Network

    D. J. Wineland; D. Leibfried; M. D. Barrett; A. Ben-Kish; J. C. Bergquist; R. B. Blakestad; J. J. Bollinger; J. Britton; J. Chiaverini; B. Demarco; D. Hume; W. M. Itano; M. Jensen; J. D. Jost; E. Knill; J. Koelemeij; C. Langer; W. Oskay; R. Ozeri; R. Reichle; T. Rosenband; T. Schaetz; P. O. Schmidt; S. Seidelin

    2005-08-02

    We briefly discuss recent experiments on quantum information processing using trapped ions at NIST. A central theme of this work has been to increase our capabilities in terms of quantum computing protocols, but we have also applied the same concepts to improved metrology, particularly in the area of frequency standards and atomic clocks. Such work may eventually shed light on more fundamental issues, such as the quantum measurement problem.

  8. 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.

  9. 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

  10. Lysosomal trapping of a radiolabeled substrate of P-glycoprotein as a mechanism for signal

    E-print Network

    Pike, Victor W.

    -gp is inhibited, [11 C]dLop, a potent opiate agonist, enters and becomes trapped in the brain. This trapping- dioactivity over time. As we previously demonstrated that this trap- ping was not caused by binding to opiate not wash out from the brain, despite declining plasma concentrations (4, 6). Although dLop is an opiate

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

    E-print Network

    Noh, Kyungyoon

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

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

    E-print Network

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

    2012-01-01

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

  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. 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

  15. Investigation of the Trapping Mechanism for Transient Current-Voltage Behavior In CIGSS-Based Solar Cells

    E-print Network

    Sites, James R.

    exposure, and applied bias in cells fabricated by Siemens Solar Industries (SSI). When a constant biasInvestigation of the Trapping Mechanism for Transient Current-Voltage Behavior In CIGSS-Based Solar Cells Pamela K. Johnson1 , James R. Sites1 and Dale E. Tarrant2 1 Colorado State University, Fort

  16. 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.

  17. 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

  18. Integrated chips and optical cavities for trapped ion quantum information processing

    E-print Network

    Leibrandt, David R

    2009-01-01

    Quantum information processing is a new and exciting field which uses quantum mechanical systems to perform information processing. At the heart of the excitement are quantum computation - which promises efficient algorithms ...

  19. UV laser beam switching system for Yb trapped ion quantum information processing

    NASA Astrophysics Data System (ADS)

    Scherer, David R.; Hensley, Joel M.; Parameswaran, Krishnan R.; Bamford, Douglas J.; Mount, Emily; Crain, Stephen; Kim, Jungsang

    2012-02-01

    Qubits based on trapped ions are being investigated as a promising platform for scalable quantum information processing. One challenge associated with the scalability of such a multi-qubit trapped ion system is the need for an ultraviolet (UV) laser beam switching and control system to independently modulate and address large qubit arrays. In this work, we propose and experimentally demonstrate a novel architecture for a laser beam control system for trapped ion quantum computing based on fast electro-optic amplitude switching and high-fidelity electromechanical beam shuttering using a microelectromechanical systems (MEMS) deflector coupled into a single-mode optical fiber. We achieve a rise/fall time of 5 ns, power extinction of -31 dB, and pulse width repeatability of > 99.95% using an electrooptic switch based on a ?-BaB2O4 (BBO) Pockels cell. A tilting MEMS mirror fabricated using a commercial foundry was used to steer UV light into a single-mode optical fiber, resulting in an electromechanical beam shutter that demonstrated a power extinction of -52 dB and a switching time of 2 ?s. The combination of these two technologies allows for high-fidelity power extinction using a platform that does not suffer from temperature-induced beam steering due to changes in modulation duty cycle. The overall system is capable of UV laser beam switching to create the resolved sideband Raman cooling pulses, algorithm pulses, and read-out pulses required for quantum computing applications.

  20. 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 (Hübner) 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

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  3. Charge trapping and luminance mechanisms of organic light-emitting devices with a 5,6,11,12-tetraphenylnaphthacene emission layer.

    PubMed

    Park, Su Hyeong; Lee, Dae Uk; Kim, Tae Whan

    2011-08-01

    The electrical and the optical properties of the organic light-emitting devices fabricated utilizing a 5,6,11,12-tetraphenylnaphthacene (rubrene) emission layer (EML) were investigated to clarify their charge trapping and luminance mechanisms. The increase in the thickness of the rubrene EML extended the width of the recombination zone, resulting in the enhancement of the efficiency and in the variation of the shoulder peak intensity of the electroluminescence spectra. The charge trapping and luminance mechanisms were affected by the total thickness of the rubrene layer, regardless of the existence of the barrier layers. The charge trapping and luminance mechanisms are described on the basis of the experimental results. PMID:22103164

  4. 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.

  5. 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.

  6. 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.

  7. Quantum Information Processing, Vol. 3, Nos. 15, October 2004 ( 2004) Quantum Information Processing with Trapped Neutral

    E-print Network

    Deutsch, Ivan H.

    and metrology. This article reviews some of the most important protocols for universal quantum logicQuantum Information Processing, Vol. 3, Nos. 1­5, October 2004 (© 2004) Quantum Information, 2004; accepted March 31, 2004 Quantum information can be processed using large ensembles of ultracold

  8. 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.

  9. Unfaulting mechanism of trapped self-interstitial atom clusters in bcc Fe: A kinetic study based on the potential energy landscape

    E-print Network

    Yildiz, Bilge

    We report on the complete unfaulting mechanism of a trapped self-interstitial atom cluster in the form of a nonparallel configuration (NPC), investigated using the autonomous basin climbing (ABC) method. A detailed set of ...

  10. 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.

  11. Lab on a Chip b718153a Numerical design of electrical-mechanical traps

    E-print Network

    Peraire, Jaime

    applied to the final version. We will publish articles on the web as soon as possible after receiving your published as an Advance Article on the web ?????? DOI: 10.1039/b718153a We present a coupled immersed the electrical techniques used to manipulate biolog- ical material, dielectrophoretic (DEP) traps show great

  12. PHYSICAL REVIEW E 83, 021911 (2011) Mechanical model of the ultrafast underwater trap of Utricularia

    E-print Network

    2011-01-01

    (Received 19 October 2010; published 18 February 2011) The underwater traps of the carnivorous plants of carnivorous plants, which are the result of adaptation to poor environments in terms of nutriments and not involve any motion of the plant itself. Plants of the genus Nepenthes are typical examples of carnivorous

  13. 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.

  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 st...

  15. 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.

  16. 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.

  17. 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

  18. 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

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

    E-print Network

    Faculty Position in Mechanical Engineering Water Conservation in Industrial Processes University of Kansas The Department of Mechanical Engineering at the University of Kansas is seeking applications in industrial processes. Exceptional candidates with outstanding qualifications could be considered

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

    E-print Network

    Waikato, University of

    , and making products to improve the quality of human life and shape the economy. Mechanical engineers apply on converting raw and commodity materials into valuable products required by manufacturers or the end consumer the principles of physics, mathematics, computing and practical skills to design mechanical systems and artefacts

  1. 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, Michael P.; Weitz, David A.

    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

  2. Diffusion with traps as the mechanism behind the retentivity relaxation of the resistive state on bipolar RRAM devices

    NASA Astrophysics Data System (ADS)

    Schulman, Alejandro; Rozenberg, Marcelo; Acha, Carlos

    2013-03-01

    The relaxation of the remnant resistance state obtained immediately after the electric-pulse switching process on metal/complex oxide interfaces [(Au, Pt) / (YBCO, LSMO)] has been studied. We have found that resistance relaxes following a stretched exponential law, with a temperature and applied switching power independent exponent. More interesting and unlike ordinary thermal diffusion processes, we observe that the characteristic relaxation time increases with increasing temperature and applied power. This anomalous dependence of the characteristic time gave us the opportunity to find an interesting physic process related to the oxygen diffusion on complex oxides, like superconducting cuprates or colossal magnetoresistant manganites: We argue that the observed behavior, common for both complex oxide interfaces, points to a generic phenomenon that can be understood as due to the diffusion of oxygen ions (or oxygen vacancies) moving on a 2D surface (grain boundaries) with a temperature dependent density of trapping centers.

  3. 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.

  4. Materials Processing Routes to Trap-Free Halide Perovskites Andrei Buin, Patrick Pietsch, Jixian Xu, Oleksandr Voznyy, Alexander H. Ip, Riccardo Comin,

    E-print Network

    Sargent, Edward H. "Ted"

    ABSTRACT: Photovoltaic devices based on lead iodide perovskite films have seen rapid advancements, recently, defect, electronic traps, diffusion length, growth, precursor Solar cells based on a methylammonium leadMaterials Processing Routes to Trap-Free Halide Perovskites Andrei Buin, Patrick Pietsch, Jixian Xu

  5. Ion traps fabricated in a CMOS foundry

    E-print Network

    Mehta, Karan Kartik

    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 ...

  6. Percolation with trapping mechanism drives active gels to the critically connected state

    E-print Network

    Chiu Fan Lee; Gunnar Pruessner

    2015-08-27

    Cell motility and tissue morphogenesis depend crucially on the dynamic remodelling of actomyosin networks. An actomyosin network consists of an actin polymer network connected by crosslinker proteins and motor protein myosins that generate internal stresses on the network. A recent discovery shows that for a range of experimental parameters, actomyosin networks contract to clusters with a power-law size distribution [Alvarado J. et al. (2013) Nature Physics 9 591]. Here, we argue that actomyosin networks can exhibit robust critical signature without fine-tuning because the dynamics of the system can be mapped onto a modified version of percolation with trapping (PT), which is known to show critical behaviour belonging to the static percolation universality class without the need of fine-tuning of a control parameter. We further employ our PT model to generate experimentally testable predictions.

  7. Percolation with trapping mechanism drives active gels to the critically connected state

    E-print Network

    Lee, Chiu Fan

    2015-01-01

    Cell motility and tissue morphogenesis depend crucially on the dynamic remodelling of actomyosin networks. An actomyosin network consists of an actin polymer network connected by crosslinker proteins and motor protein myosins that generate internal stresses on the network. A recent discovery shows that for a range of experimental parameters, actomyosin networks contract to clusters with a power-law size distribution [Alvarado J. et al. (2013) Nature Physics 9 591]. Here, we argue that actomyosin networks can exhibit robust critical signature without fine-tuning because the dynamics of the system can be mapped onto a modified version of percolation with trapping (PT), which is known to show critical behaviour belonging to the static percolation universality class without the need of fine-tuning of a control parameter. We further employ our PT model to generate experimentally testable predictions.

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

    SciTech Connect

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

    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.

  9. Role of Krev Interaction Trapped-1 in Prostacyclin-Induced Protection against Lung Vascular Permeability Induced by Excessive Mechanical Forces and Thrombin Receptor Activating Peptide 6.

    PubMed

    Meliton, Angelo; Meng, Fanyong; Tian, Yufeng; Shah, Alok A; Birukova, Anna A; Birukov, Konstantin G

    2015-12-01

    Mechanisms of vascular endothelial cell (EC) barrier regulation during acute lung injury (ALI) or other pathologies associated with increased vascular leakiness are an active area of research. Adaptor protein krev interaction trapped-1 (KRIT1) participates in angiogenesis, lumen formation, and stabilization of EC adherens junctions (AJs) in mature vasculature. We tested a role of KRIT1 in the regulation of Rho-GTPase signaling induced by mechanical stimulation and barrier dysfunction relevant to ventilator-induced lung injury and investigated KRIT1 involvement in EC barrier protection by prostacyclin (PC). PC stimulated Ras-related protein 1 (Rap1)-dependent association of KRIT1 with vascular endothelial cadherin at AJs, with KRIT1-dependent cortical cytoskeletal remodeling leading to EC barrier enhancement. KRIT1 knockdown exacerbated Rho-GTPase activation and EC barrier disruption induced by pathologic 18% cyclic stretch and thrombin receptor activating peptide (TRAP) 6 and attenuated the protective effects of PC. In the two-hit model of ALI caused by high tidal volume (HTV) mechanical ventilation and TRAP6 injection, KRIT1 functional deficiency in KRIT1(+/-) mice increased basal lung vascular leak and augmented vascular leak and lung injury caused by exposure to HTV and TRAP6. Down-regulation of KRIT1 also diminished the protective effects of PC against TRAP6/HTV-induced lung injury. These results demonstrate a KRIT1-dependent mechanism of vascular EC barrier control in basal conditions and in the two-hit model of ALI caused by excessive mechanical forces and TRAP6 via negative regulation of Rho activity and enhancement of cell junctions. We also conclude that the stimulation of the Rap1-KRIT1 signaling module is a major mechanism of vascular endothelial barrier protection by PC in the injured lung. PMID:25923142

  10. 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.

  11. 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.

  12. Process for predicting structural performance of mechanical systems

    DOEpatents

    Gardner, David R. (Albuquerque, NM); Hendrickson, Bruce A. (Albuquerque, NM); Plimpton, Steven J. (Albuquerque, NM); Attaway, Stephen W. (Cedar Crest, NM); Heinstein, Martin W. (Albuquerque, NM); Vaughan, Courtenay T. (Albuquerque, NM)

    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.

  13. 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.

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

    PubMed Central

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

    2013-01-01

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

  15. 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...

  16. 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...

  17. 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.

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

    PubMed Central

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

    2014-01-01

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

  19. 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.

  20. BSc in Mechanical Engineering Process Engineering spec.

    E-print Network

    Levente, Buttyán

    water. Wastewater sludge treatment techniques, sludge disposal. Part III. Treatment of gaseous knowledge in air pollution control, wastewater treatment and solid wastes management for mechanical problems in topics of air pollution control, wastewater and solid wastes management. Based

  1. Convergence of clock processes on infinite graphs and aging in Bouchaud's asymmetric trap model on ${\\Bbb Z}^d$

    E-print Network

    Véronique Gayrard; Adela Svejda

    2015-01-13

    Using a method developed by Durrett and Resnick [22] we establish general criteria for the convergence of properly rescaled clock processes of random dynamics in random environments on infinite graphs. This complements the results of [26], [19], and [20]: put together these results provide a unified framework for proving convergence of clock processes. As a first application we prove that Bouchaud's asymmetric trap model on ${\\Bbb Z}^d$ exhibits a normal aging behavior for all $d\\geq 2$. Namely, we show that certain two-time correlation functions, among which the classical probability to find the process at the same site at two time points, converge, as the age of the process diverges, to the distribution function of the arcsine law. As a byproduct we prove that the fractional kinetics process ages.

  2. 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)?(+)(u)(v = 0, J = 0) ground state using a resonant three-photon excitation sequence via the B (1)?(+)(u)(v = 3, J = 1) and I (1)?(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

  3. Trapping of phenylacetaldehyde as a key mechanism responsible for naringenin's inhibitory activity in mutagenic 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine formation.

    PubMed

    Cheng, Ka-Wing; Wong, Chi Chun; Cho, Chi Kong; Chu, Ivan K; Sze, Kong Hung; Lo, Clive; Chen, Feng; Wang, Mingfu

    2008-10-01

    Chemical model reactions were carried out to investigate the mechanism of inhibition by a citrus flavonoid, naringenin, on the formation of 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP), the most abundant mutagenic heterocyclic amine found in foods. GC-MS showed that naringenin dose dependently reduced the level of phenylacetaldehyde, a key intermediate on the pathway to the formation of PhIP. Subsequent LC-MS analyses of samples from a wide range of model systems consisting of PhIP precursors, including phenylalanine, glucose, and creatinine, suggested that naringenin scavenged phenylacetaldehyde via adduct formation. An isotope-labeling study showed that the postulated adducts contain fragment(s) of phenylalanine origin. Direct reaction employing phenylacetaldehyde and naringenin further confirmed the capability of naringenin to form adducts with phenylacetaldehyde, thus reducing its availability for PhIP formation. Two of the adducts were subsequently isolated and purified. Their structure was elucidated by one- and two-dimensional NMR spectroscopy as 8- C-( E-phenylethenyl)naringenin (1) and 6- C-( E-phenylethenyl)naringenin (2), respectively, suggesting that C-6 and C-8 are two of the active sites of naringenin in adduct formation. These two adducts were also identified from thermally processed beef models, highlighting phenylacetaldehyde trapping as a key mechanism of naringenin to inhibit PhIP formation. PMID:18702534

  4. 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)

  5. Realization of unbiased photoresponse in amorphous InGaZnO ultraviolet detector via a hole-trapping process

    NASA Astrophysics Data System (ADS)

    Jiang, D. L.; Li, L.; Chen, H. Y.; Gao, H.; Qiao, Q.; Xu, Z. K.; Jiao, S. J.

    2015-04-01

    A metal-semiconductor-metal (MSM) structure ultraviolet photodetector has been fabricated from amorphous InGaZnO (a-IGZO) film at room temperature. The photodetector can work without consuming external power and show a responsivity of 4 mA/W. The unbiased photoresponse characteristic is attributed to the hole-trapping process occurred in the electrode/a-IGZO interface, and a physical model based on band energy theory is proposed to explain the origin of the photoresponse at zero bias in our device. Our findings may provide a way to realize unbiased photoresponse in the simple MSM structure.

  6. 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.

  7. 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.

  8. Material removal processes: Engineering mechanics consideration

    SciTech Connect

    Anderson, C.A.

    1993-04-01

    In the material removal process called machining, a layer of material of constant thickness is removed from the workpiece by a wedge-shaped tool that travels parallel to the workpiece at a preselected depth. Even though the speed of relative movement between workpiece and tool is low (typical 1--10 M/S), the strain-rates in the workpiece near the tool can be high, on the order of 10{sup 4}-10{sup 5} s{sup {minus}1}. When machining brittle materials or unlubricated ductile materials at low speed, the removed metal (or chip) will be discontinuous and made up of small fractured segments. On the other hand, when machining ductile material under lubricated conditions, the removed material forms a continuous coil. In this case, we can represent the material removal process as a steady-state process. In this presentation, we will restrict ourselves to orthogonal machining where the cutting edge is perpendicular to the relative motion-a situation also approximated by other material removal processes such as planing and broaching, and turning on a lathe.

  9. Material removal processes: Engineering mechanics consideration

    SciTech Connect

    Anderson, C.A.

    1993-01-01

    In the material removal process called machining, a layer of material of constant thickness is removed from the workpiece by a wedge-shaped tool that travels parallel to the workpiece at a preselected depth. Even though the speed of relative movement between workpiece and tool is low (typical 1--10 M/S), the strain-rates in the workpiece near the tool can be high, on the order of 10[sup 4]-10[sup 5] s[sup [minus]1]. When machining brittle materials or unlubricated ductile materials at low speed, the removed metal (or chip) will be discontinuous and made up of small fractured segments. On the other hand, when machining ductile material under lubricated conditions, the removed material forms a continuous coil. In this case, we can represent the material removal process as a steady-state process. In this presentation, we will restrict ourselves to orthogonal machining where the cutting edge is perpendicular to the relative motion-a situation also approximated by other material removal processes such as planing and broaching, and turning on a lathe.

  10. 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…

  11. Tailored Coupled Spin Systems with Microwave-Driven Trapped Ions for Quantum Information Processing

    E-print Network

    Ch. Piltz; Th. Sriarunothai; S. Ivanov; S. Wölk; Ch. Wunderlich

    2015-09-04

    A quantum simulator allows for investigating static and dynamic properties of a complex quantum system, difficult to access directly, by means of another physical system that is well understood and controlled. A universal quantum computer would be suitable for that purpose. However, other, more specialized physical systems -- already in close experimental reach -- promise groundbreaking new insight in quantum phenomena when used as quantum simulators. Here, we show how a tailored and versatile effective spin-system suitable for quantum simulations and universal quantum computation is realized using trapped atomic ions. Each single spin can be addressed individually, and, simply by the application of microwave pulses, selected spins can be decoupled from the remaining system. Furthermore, the sign of the couplings can be changed, as well as the effective strength of spin-spin coupling determined. Thus, all operations for a versatile quantum simulator are implemented. In addition, taking advantage of simultaneous coupling between three spins a coherent quantum Fourier transform -- an essential building block for many quantum algorithms -- is efficiently realized. This approach based on microwave-driven trapped ions, complementary to laser-based methods, opens a new route to overcome technical and physics challenges in the quest for a quantum simulator and quantum computer.

  12. Volcanic ash layer depth: Processes and mechanisms

    NASA Astrophysics Data System (ADS)

    Dacre, Helen

    2015-04-01

    The long duration of the 2010 Eyjafjallajokull eruption provided a unique opportunity to measure a widely dispersed volcanic ash cloud. Layers of volcanic ash were observed by the European Aerosol Research LIdar NETwork (EARLINET) with a mean depth of 1.2 km and standard deviation of 0.9 km. In this presentation we evaluate the ability of the UK Met Office's Numerical Atmospheric-dispersion Modelling Environment (NAME) to simulate the observed ash layers and examine the processes controlling their depth. NAME simulates distal ash layer depths exceptionally well with a mean depth of 1.2 km and standard deviation of 0.7 km. The dominant process determining the depth of ash layers over Europe is the balance between the vertical wind shear (which acts to reduce the depth of the ash layers) and vertical turbulent mixing (which acts to deepen the layers). Interestingly, differential sedimentation of ash particles and the volcano vertical emission profile play relatively minor roles.

  13. Volcanic ash layer depth: Processes and mechanisms

    NASA Astrophysics Data System (ADS)

    Dacre, H. F.; Grant, A. L. M.; Harvey, N. J.; Thomson, D. J.; Webster, H. N.; Marenco, F.

    2015-01-01

    The long duration of the 2010 Eyjafjallajökull eruption provided a unique opportunity to measure a widely dispersed volcanic ash cloud. Layers of volcanic ash were observed by the European Aerosol Research Lidar Network with a mean depth of 1.2 km and standard deviation of 0.9 km. In this paper we evaluate the ability of the Met Office's Numerical Atmospheric-dispersion Modelling Environment (NAME) to simulate the observed ash layers and examine the processes controlling their depth. NAME simulates distal ash layer depths exceptionally well with a mean depth of 1.2 km and standard deviation of 0.7 km. The dominant process determining the depth of ash layers over Europe is the balance between the vertical wind shear (which acts to reduce the depth of the ash layers) and vertical turbulent mixing (which acts to deepen the layers). Interestingly, differential sedimentation of ash particles and the volcano vertical emission profile play relatively minor roles.

  14. Blandford-Znajek mechanism versus Penrose process

    E-print Network

    S. S. Komissarov

    2008-04-11

    During the three decades since its theoretical discovery the Blandford-Znajek process of extracting the rotational energy of black holes has become one of the foundation stones in the building of modern relativistic astrophysics. However, it is also true that for a long time its physics was not well understood, as evidenced by the controversy that surrounded it since 1990s. Thanks to the efforts of many theorists during the last decade the state of affairs is gradually improving. In this lecture I attempt to explain the key ingredients of this process in more or less systematic, rigorous, and at the same time relatively simple fashion. A particular attention is paid to the similarities and differences between the Blandford-Znajek and Penrose processes. To this purpose I formulate the notion of energy counter flow. The concept of horizon membrane is replaced with the concept of vacuum as an electromagnetically active medium. The effect of negative phase velocity of electromagnetic waves in the black hole ergosphere is also discussed.

  15. Ultra-fast underwater suction traps

    PubMed Central

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

    2011-01-01

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

  16. Formation process and mechanical property of slickenside

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  17. 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.

  18. Statistical mechanics of non-Markovian exclusion processes 

    E-print Network

    Concannon, Robert James

    2014-06-28

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

  19. 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

  20. 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.

  1. 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.

  2. J. Neurophysiol. 1999, in press. Neural mechanisms for processing binocular

    E-print Network

    Freeman, Ralph D.

    J. Neurophysiol. 1999, in press. Neural mechanisms for processing binocular information I. Simple, University of California, Berkeley, CA 94720-2020 Short title: Processing of binocular information by simple-sequences,wehavedeterminedtherulesofbinocularinteractionsexhibitedbysimplecells in the cat's striate cortex in relation to the structure of their monocular RFs. We find that binocular

  3. J. Neurophysiol. 1999, in press. Neural mechanisms for processing binocular

    E-print Network

    Freeman, Ralph D.

    J. Neurophysiol. 1999, in press. Neural mechanisms for processing binocular information II. Complex, University of California, Berkeley, CA 94720-2020 Short title: Processing of binocular information by complex, and binocular disparity, examination of the RF properties of subunits is important

  4. J. Neurophysiol. 1999, in press. Neural mechanisms for processing binocular

    E-print Network

    Freeman, Ralph D.

    J. Neurophysiol. 1999, in press. Neural mechanisms for processing binocular information II. Complex, University of California, Berkeley, CA 94720­2020 Short title: Processing of binocular information by complex, and binocular disparity, examination of the RF properties of subunits is important for understanding functional

  5. J. Neurophysiol. 1999, in press. Neural mechanisms for processing binocular

    E-print Network

    Freeman, Ralph D.

    J. Neurophysiol. 1999, in press. Neural mechanisms for processing binocular information I. Simple, University of California, Berkeley, CA 94720­2020 Short title: Processing of binocular information by simple­sequences, wehavedetermined the rules of binocular interactions exhibited by simple cells in the cat's striate cortex

  6. RIVER WIDTH ADJUSTMENT. I: PROCESSES AND MECHANISMS By the ASCE Task Committee on Hydraulics, Bank Mechanics,

    E-print Network

    Julien, Pierre Y.

    RIVER WIDTH ADJUSTMENT. I: PROCESSES AND MECHANISMS By the ASCE Task Committee on Hydraulics, Bank Mechanics, and Modeling of River Width Adjustmentl ABSTRACT: In 1993 a Task Committee (TC) of the ASCE either due to natural instability or in response to changes in watershed land use, river regulation

  7. Adiabatic shear mechanisms for the hard cutting process

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  8. 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

  9. 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.

  10. Application of PLM processes to respond to mechanical SMEs needs

    E-print Network

    Duigou, Julien Le; Perry, Nicolas; Delplace, Jean-Charles

    2010-01-01

    PLM is today a reality for mechanical SMEs. Some companies implement PLM systems very well but others have more difficulties. This paper aims to explain why some SMEs do not success to integrated PLM systems analyzing the needs of mechanical SMEs, the processes to implement to respond to those needs and the actual PLM software functionalities. The proposition of a typology of those companies and the responses of those needs by PLM processes will be explain through the applications of a demonstrator applying appropriate generic data model and modelling framework.

  11. Application of PLM processes to respond to mechanical SMEs needs

    E-print Network

    Julien Le Duigou; Alain Bernard; Nicolas Perry; Jean-Charles Delplace

    2010-11-26

    PLM is today a reality for mechanical SMEs. Some companies implement PLM systems very well but others have more difficulties. This paper aims to explain why some SMEs do not success to integrated PLM systems analyzing the needs of mechanical SMEs, the processes to implement to respond to those needs and the actual PLM software functionalities. The proposition of a typology of those companies and the responses of those needs by PLM processes will be explain through the applications of a demonstrator applying appropriate generic data model and modelling framework.

  12. 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

  13. 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.

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

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

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

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

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

  18. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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

  19. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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

  20. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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

  1. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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

  2. 40 CFR 408.190 - Applicability; description of the West Coast mechanized salmon processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  3. 40 CFR 408.170 - Applicability; description of the Alaskan mechanized salmon processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  4. 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…

  5. 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.

  6. 45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Mechanized claims processing and information retrieval systems; definitions. 205...Mechanized claims processing and information retrieval systems; definitions. Section...automated statewide management information system, conditions for FFP...

  7. 45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Mechanized claims processing and information retrieval systems; definitions. 205...Mechanized claims processing and information retrieval systems; definitions. Section...automated statewide management information system, conditions for FFP...

  8. 45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Mechanized claims processing and information retrieval systems; definitions. 205...Mechanized claims processing and information retrieval systems; definitions. Section...automated statewide management information system, conditions for FFP...

  9. 45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Mechanized claims processing and information retrieval systems; definitions. 205...Mechanized claims processing and information retrieval systems; definitions. Section...automated statewide management information system, conditions for FFP...

  10. 45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Mechanized claims processing and information retrieval systems; definitions. 205...Mechanized claims processing and information retrieval systems; definitions. Section...automated statewide management information system, conditions for FFP...

  11. 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.

  12. 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.

  13. 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.

  14. The role of epigenetic mechanisms and processes in autoimmune disorders

    PubMed Central

    Greer, Judith M; McCombe, Pamela A

    2012-01-01

    The lack of complete concordance of autoimmune disease in identical twins suggests that nongenetic factors play a major role in determining disease susceptibility. In this review, we consider how epigenetic mechanisms could affect the immune system and effector mechanisms in autoimmunity and/or the target organ of autoimmunity and thus affect the development of autoimmune diseases. We also consider the types of stimuli that lead to epigenetic modifications and how these relate to the epidemiology of autoimmune diseases and the biological pathways operative in different autoimmune diseases. Increasing our knowledge of these epigenetic mechanisms and processes will increase the prospects for controlling or preventing autoimmune diseases in the future through the use of drugs that target the epigenetic pathways. PMID:23055689

  15. Coupled mechanical-oxidation modeling during silicon thermal oxidation process

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Zhang, Xian-Cheng; Tu, Shan-Tung

    2015-09-01

    This work provided an analytical model to solve the coupled mechanical-oxidation problem during the silicon thermal oxidation process. The silicon thermal oxidation behavior under two different mechanical load conditions, i.e., constant strain and uniaxial stress, were considered. The variations of oxide stress and scale thickness along with oxidation time were predicted. During modeling, all the effects of stress accumulation due to growth strain, stress relaxation due to viscous flow and the external load on the scale growth rate were taken into consideration. Results showed that the existence of external loads had an obvious influence on the oxide stress and scale thickness. Generally, tensile stress or strain accelerated the oxidant diffusion process. However, the reaction rate at the Si/SiO2 interface was retarded under uniaxial stress, which was not found in the case of constant strain load.

  16. 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.

  17. 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.

  18. Magnetic Penrose Process and Blanford-Zanejk mechanism: A clarification

    E-print Network

    Dadhich, Naresh

    2012-01-01

    The Penrose process (PP) is an ingenious mechanism of extracting rotational energy from a rotating black hole, however it was soon realized that it was not very efficient for its astrophysical applications for powering the central engine of quasars and AGNs. The situation however changed dramatically in the presence of magnetic field produced by the accretion disk surrounding the hole in the equatorial plane. In 1985, Wagh, Dhurandhar and Dadhich had for the first time considered the magnetic Penrose process (MPP) in which the magnetic field could now provide the energy required for a fragment to ride on negative energy orbit thereby overcoming the stringent velocity constraint of the original PP. Thus MPP turned very efficient and so much so that efficiency could now even exceed 100 percent. They had in principle established revival of PP for astrophysical applications in powering the high energy sources. MPP is however similar to the earlier discovered and well known Blandford-Znajeck (BZ) mechanism in whic...

  19. 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

  20. 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.

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

    PubMed

    Segura-Aguilar, Juan; Kostrzewa, Richard M

    2015-04-01

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

  2. 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.

  3. Fast accumulation of ions in a dual trap

    NASA Astrophysics Data System (ADS)

    Kamsap, M. R.; Champenois, C.; Pedregosa-Gutierrez, J.; Houssin, M.; Knoop, M.

    2015-06-01

    Transporting charged particles between different traps has become an important feature in high-precision spectroscopy experiments of different types. In many experiments in atomic and molecular physics, the optical probing of the ions is not carried out at the same location as the creation or state preparation. In our double linear radio-frequency trap, we have implemented a fast protocol allowing to shuttle large ion clouds very efficiently between traps, in times shorter than a millisecond. Moreover, our shuttling protocol is a one-way process, allowing to add ions to an existing cloud without loss of the already trapped sample. This feature makes accumulation possible, resulting in the creation of large ion clouds. Experimental results show that ion clouds of large size are reached with laser cooling; however, the described mechanism does not rely on any cooling process.

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

    PubMed Central

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

    2014-01-01

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

  5. 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.

  6. Plant uprooting by flow as a fatigue mechanical process

    NASA Astrophysics Data System (ADS)

    Perona, Paolo; Edmaier, Katharina; Crouzy, Benoît

    2015-04-01

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

  7. 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.

  8. 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

  9. Folding of the apolipoprotein A1 driven by the salt concentration as a possible mechanism to improve cholesterol trapping

    E-print Network

    M. A. Balderas Altamirano; A. Gama Goicochea; E. Pérez

    2014-06-11

    The folding of the cholesterol trapping apolipoprotein A1 in aqueous solution at increasing ionic strength is studied using atomically detailed molecular dynamics simulations. We calculate various structural properties to characterize the conformation of the protein, such as the radius of gyration, the radial distribution function and the end to end distance. Additionally we report information using tools specifically tailored for the characterization of proteins, such as the mean smallest distance matrix and the Ramachandran plot. We find that two qualitatively different configurations of this protein are preferred, one where the protein is extended, and one where it forms loops or closed structures. It is argued that the latter promote the association of the protein with cholesterol and other fatty acids.

  10. 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

  11. Diffusion Processes in Phase Spaces and Quantum Mechanics

    E-print Network

    E. M. Beniaminov

    2008-03-18

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

  12. 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.

  13. 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.

  14. 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.

  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. Processing mechanics of alternate twist ply (ATP) yarn technology

    NASA Astrophysics Data System (ADS)

    Elkhamy, Donia Said

    Ply yarns are important in many textile manufacturing processes and various applications. The primary process used for producing ply yarns is cabling. The speed of cabling is limited to about 35m/min. With the world's increasing demands of ply yarn supply, cabling is incompatible with today's demand activated manufacturing strategies. The Alternate Twist Ply (ATP) yarn technology is a relatively new process for producing ply yarns with improved productivity and flexibility. This technology involves self plying of twisted singles yarn to produce ply yarn. The ATP process can run more than ten times faster than cabling. To implement the ATP process to produce ply yarns there are major quality issues; uniform Twist Profile and yarn Twist Efficiency. The goal of this thesis is to improve these issues through process modeling based on understanding the physics and processing mechanics of the ATP yarn system. In our study we determine the main parameters that control the yarn twist profile. Process modeling of the yarn twist across different process zones was done. A computational model was designed to predict the process parameters required to achieve a square wave twist profile. Twist efficiency, a measure of yarn torsional stability and bulk, is determined by the ratio of ply yarn twist to singles yarn twist. Response Surface Methodology was used to develop the processing window that can reproduce ATP yarns with high twist efficiency. Equilibrium conditions of tensions and torques acting on the yarns at the self ply point were analyzed and determined the pathway for achieving higher twist efficiency. Mechanistic modeling relating equilibrium conditions to the twist efficiency was developed. A static tester was designed to zoom into the self ply zone of the ATP yarn. A computer controlled, prototypic ATP machine was constructed and confirmed the mechanistic model results. Optimum parameters achieving maximum twist efficiency were determined in this study. The successful results of this work have led to the filing of a US patent disclosing the method for producing ATP yarns with high yarn twist efficiency using a high convergence angle at the self ply point together with applying ply torque.

  17. 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)

  18. 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."

  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. Methodology to reduce chronic defect mechanisms in semiconductor processing

    NASA Astrophysics Data System (ADS)

    Ecton, Timothy W.; Frazee, Kenneth G.

    1990-06-01

    This paper docuitents a structur approach to defect elimination in seiiiccructor processing. Classical problem solving techniques were used to logically guide the defect rIuction effort. tfect infontation was gatherei using an automated wafer inspection systeaii ar defects were classifi&1 by production workers on a rete review station. This approach distiruishe actual causes from several probable causes. A process change has reduc the defect mechanism. This methodology was applied to ruce !IEFWN' perfluoroalkoxy (PFA) particles in a one micron semiccructor process. Electrical test structures identified a critical layer where yield loss was occurring. An audit procedure was establishi at this layer arx defects were c1assifi into broad cateories. Further breakout of defect t'pes by appearance was necessaxy to construct a meaningful Pareto chart ard identify the xist fr&ijiently occurring fatal defect. The critical process zone was segmented using autaat wafer inspection to isolate the step causing the defect. An IshiJcawa or cause-effect diagram was construct with input from process engineers to outline all possible causes of the defect. A nest probable branch was selected for investigation arxi pursued until it became clear that this branch was not related to the cause. At this point, new ideas were sought from a sister production facility. ring the visit a breakthrough irxicat& a different path ar ultiltiately lead to identifying the source of the defect. A process change was implemented. An evaluation of the change she1 a substantial decrease in defect evel. rther efforts to eliminate the defect srce are in rogres.

  1. 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.

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  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. Trapped Particles in $PT$ Symmetric Theories

    E-print Network

    C. Yuce; A. Kurt; A. Kucukaslan

    2006-02-13

    $PT$ symmetric quantum mechanics for a particle trapped by the generalized non-Hermitian harmonic oscillator potential is studied. It is shown that energy and the expectation value of the position operator $x$ can not be real simultaneously, if the particle is trapped. Non-vanishing boundary conditions for the trapped particle in $PT$ symmetric theory are also discussed.

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

    PubMed

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

    2015-07-16

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

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. Formation of trapped-ion population in the process of charging of an absorbing sphere in a collisionless plasma

    NASA Astrophysics Data System (ADS)

    Kiselyov, A. A.; Dolgonosov, M. S.; Krasovsky, V. L.

    2015-07-01

    Dynamics of charging of an absorbing spherical body is studied by means of a numerical simulation. Upon saturation of the charge of the body and relaxation of transient oscillatory phenomena accompanying the charging, the disturbed plasma passes into a stable steady state. Along with the determination of space-time dependences of electrostatic quantities, the numerical experiment allows to observe the time evolution of electron and ion distributions in phase space. A dense cloud of trapped ions is formed near the spherical body, provided that the ion Debye length is of the order of the radius of the body, and the electron Debye length exceeds appreciably the radius. The trapped ions contribute substantially to the screening of the charged sphere, thereby affecting the structure of the disturbed plasma in the asymptotic steady state at long times.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  1. 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.

  2. Neutrophil extracellular trap-derived enzymes oxidize high-density lipoprotein: an additional proatherogenic mechanism in systemic lupus erythematosus

    PubMed Central

    Tang, Chongren; Knight, Jason S.; Mathew, Anna; Padilla, Robin L.; Gillespie, Brenda W; Carmona-Rivera, Carmelo; Liu, Xiaodan; Subramanian, Venkataraman; Hasni, Sarfaraz; Thompson, Paul R.; Heinecke, Jay W.; Saran, Rajiv; Pennathur, Subramaniam; Kaplan, Mariana J.

    2014-01-01

    Objective Oxidative stress and oxidized high-density lipoprotein (oxHDL) are implicated as risk factors for cardiovascular disease (CVD) in systemic lupus erythematosus (SLE). Yet, how HDL is oxidized and rendered dysfunctional in SLE remains unclear. Neutrophil extracellular traps (NETs), which are elevated in lupus, possess oxidant-generating enzymes including myeloperoxidase (MPO), NADPH oxidase (NOX) and nitric oxide synthase (NOS). We hypothesized that NETs mediate HDL oxidation, impairing cholesterol efflux capacity (CEC). Methods Control and lupus plasma MPO levels and CEC activity were examined; 3-chlorotyrosine (MPO-specific) and 3-nitrotyrosine (derived from reactive nitrogen species) were quantified in human HDL. Multivariable linear models estimated and tested differences between groups. HDL was exposed to NETs from control and lupus neutrophils in the presence or absence of MPO, NOX, NOS inhibitors and chloroquine. Murine HDL oxidation was quantified after NET inhibition in vivo. Results SLE subjects displayed higher MPO levels and diminished CEC. SLE HDL had higher 3-nitrotyrosine and 3-chlorotyrosine content, with site-specific oxidation signatures on apoA1. Experiments with human and murine NETs confirmed that chlorination is mediated by MPO and NOX, and nitration by NOS and NOX. Lupus mice treated with the NET-inhibitor Cl-amidine displayed significantly decreased oxHDL. Chloroquine inhibited NET formation in vitro. Conclusion Active NOS, NOX and MPO within NETs significantly modify HDL, rendering the lipoprotein proatherogenic. As NET formation is enhanced in SLE, these findings support a novel role for NET-derived lipoprotein oxidation in SLE-associated CVD and identify additional proatherogenic roles of neutrophils and putative protective roles of antimalarials in autoimmunity. PMID:24838349

  3. 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.

  4. 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.

  5. Mechanism of Processive Movement of Monomeric and Dimeric Kinesin Molecules

    PubMed Central

    Xie, Ping

    2010-01-01

    Kinesin molecules are motor proteins capable of moving along microtubule by hydrolyzing ATP. They generally have several forms of construct. This review focuses on two of the most studied forms: monomers such as KIF1A (kinesin-3 family) and dimers such as conventional kinesin (kinesin-1 family), both of which can move processively towards the microtubule plus end. There now exist numerous models that try to explain how the kinesin molecules convert the chemical energy of ATP hydrolysis into the mechanical energy to “power” their proceesive movement along microtubule. Here, we attempt to present a comprehensive review of these models. We further propose a new hybrid model for the dimeric kinesin by combining the existing models and provide a framework for future studies in this subject. PMID:21060728

  6. Association between central auditory processing mechanism and cardiac autonomic regulation

    PubMed Central

    2014-01-01

    Background This study was conducted to describe the association between central auditory processing mechanism and the cardiac autonomic regulation. Methods It was researched papers on the topic addressed in this study considering the following data bases: Medline, Pubmed, Lilacs, Scopus and Cochrane. The key words were: “auditory stimulation, heart rate, autonomic nervous system and P300”. Results The findings in the literature demonstrated that auditory stimulation influences the autonomic nervous system and has been used in conjunction with other methods. It is considered a promising step in the investigation of therapeutic procedures for rehabilitation and quality of life of several pathologies. Conclusion The association between auditory stimulation and the level of the cardiac autonomic nervous system has received significant contributions in relation to musical stimuli. PMID:24834128

  7. 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.

  8. Neural Mechanisms and Information Processing in Recognition Systems.

    PubMed

    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

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  11. PHYSICAL REVIEW E 84, 041928 (2011) Different mechanics of snap-trapping in the two closely related carnivorous plants

    E-print Network

    2011-01-01

    carnivorous plants Dionaea muscipula and Aldrovanda vesiculosa Simon Poppinga1 and Marc Joyeux2,* 1 Plant aquatic waterwheel plant (Aldrovanda vesiculosa L.) and the closely related terrestrial venus flytrap curvature. In this paper, we present detailed mechanical models for these plants, which are based

  12. 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.

  13. Principles of an enhanced MBR-process with mechanical cleaning.

    PubMed

    Rosenberger, S; Helmus, F P; Krause, S; Bareth, A; Meyer-Blumenroth, U

    2011-01-01

    Up to date, different physical and chemical cleaning protocols are necessary to limit membrane fouling in membrane bioreactors. This paper deals with a mechanical cleaning process, which aims at the avoidance of hypochlorite and other critical chemicals in MBR with submerged flat sheet modules. The process basically consists of the addition of plastic particles into the loop circulation within submerged membrane modules. Investigations of two pilot plants are presented: Pilot plant 1 is equipped with a 10 m(2) membrane module and operated with a translucent model suspension; pilot plant 2 is equipped with four 50 m(2) membrane modules and operated with pretreated sewage. Results of pilot plant 1 show that the establishment of a fluidised bed with regular particle distribution is possible for a variety of particles. Particles with maximum densities of 1.05 g/cm(3) and between 3 and 5 mm diameter form a stable fluidised bed almost regardless of activated sludge concentration, viscosity and reactor geometry. Particles with densities between 1.05 g/cm(3) and 1.2 g/cm(3) form a stable fluidised bed, if the velocity at the reactor bottom is sufficiently high. Activities within pilot plant 2 focused on plant optimisation and the development of an adequate particle retention system. PMID:22105114

  14. 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 300-400°C 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.

  15. 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.

  16. Ion traps fabricated in a CMOS foundry

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  17. Ion traps fabricated in a CMOS foundry

    E-print Network

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

    2014-01-01

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

  18. Ion traps fabricated in a CMOS foundry

    E-print Network

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

    2014-06-13

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

  19. 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.

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

    NASA Astrophysics Data System (ADS)

    Kim, Yeong E.; Passell, Thomas O.

    2006-02-01

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

  1. Trapping Coyotes 

    E-print Network

    Texas Wildlife Services

    2008-04-15

    foot hind foot front foot hind foot Coyote Tracks Dog Tracks 2 1 ? 2 i n c h e s Inches certain trail, or have become wary of scent sets. The trap is set on the trail with small pebbles or sticksplacedoneachsideofthetraptoguidethe animalintoit...

  2. ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS Preparation of Squeezed State and Entanglement State Between Vibrational Motion of Trapped Ion and Light

    NASA Astrophysics Data System (ADS)

    Wang, Zhong-Jie

    2010-12-01

    Several schemes have been proposed to prepare two-mode squeezed state and entanglement state between motional states of a single trapped ion and light. Preparation of two-mode squeezed state is based on interaction of a trapped ion located in light cavity with cavity field. Preparation of entanglement state is based on interaction of a trapped ion located in light cavity with cavity field and a traveling wave light field.

  3. Thermoelectrically cooled water trap

    DOEpatents

    Micheels, Ronald H. (Concord, MA)

    2006-02-21

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

  4. 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.

  5. 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 55°C and that the antioxidants are formed subsequently by thermal reaction at 75 °C. The heating assay of saccharide solutions revealed glucose and isomaltose as HMF and GMF precursors, respectively, and thus the novel finding of GMF formation from isomaltose. Finally, HMF and GMF were effectively formed by two-step heating from glucose and isomaltose present in koji. PMID:25977038

  6. 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.

  7. Exploring Frontiers in Kinetics and Mechanisms of Geochemical Processes at the Mineral/Water Interface

    E-print Network

    Sparks, Donald L.

    Exploring Frontiers in Kinetics and Mechanisms of Geochemical Processes at the Mineral geochemical processes including surface complexation, mineral transformations, and oxidation in the Earth's Critical Zone is the kinetics. The timescales for geochemical processes range from milliseconds

  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. Addition of mechanically processed cellulosic fibers to ionomer cement: mechanical properties.

    PubMed

    Silva, Rafael Menezes; Carvalho, Vinícius Xavier Mattar de; Dumont, Vitor César; Santos, Maria Helena; Carvalho, Ana Márcia Macedo Ladeira

    2015-01-01

    In this study, conventional restorative glass ionomer cement (GIC) was modified by embedding it with mechanically processed cellulose fibers. Two concentrations of fibers were weighed and agglutinated into the GIC during manipulation, yielding Experimental Groups 2 (G2; 3.62 wt% of fibers) and 3 (G3; 7.24 wt% of fibers), which were compared against a control group containing no fibers (G1). The compressive strengths and elastic modulus of the three groups, and their diametral tensile strengths and stiffness, were evaluated on a universal test machine. The compressive and diametral tensile strengths were significantly higher in G3 than in G1. Statistically significant differences in elastic modulus were also found between G2 and G1 and between G2 and G3, whereas the stiffness significantly differed between G1 and G2. The materials were then characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Heterogeneously shaped particles were found on the G2 and G3 surfaces, and the cement matrices were randomly interspersed with long intermingled fibers. The EDS spectra of the composites revealed the elemental compositions of the precursor materials. The physically processed cellulosic fibers (especially at the higher concentration) increased the compressive and diametral tensile strengths of the GIC, and demonstrated acceptable elastic modulus and stiffness. PMID:25627882

  10. On the similarity of macromolecular responses to high-energy processes: mechanical milling vs. irradiation

    E-print Network

    On the similarity of macromolecular responses to high-energy processes: mechanical milling vs. In this work, we explore a variety of similarities between mechanically-milled and irradiated polymers in terms-state processing. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Mechanical milling; Solid

  11. Mechanism of FGF23 processing in fibrous dysplasia.

    PubMed

    Bhattacharyya, Nisan; Wiench, Malgorzata; Dumitrescu, Claudia; Connolly, Brian M; Bugge, Thomas H; Patel, Himatkumar V; Gafni, Rachel I; Cherman, Natasha; Cho, Monique; Hager, Gordon L; Collins, Michael T

    2012-05-01

    Fibroblast growth factor-23 (FGF23) is a phosphate- and vitamin D-regulating hormone derived from osteoblasts/osteocytes that circulates in both active (intact, iFGF23) and inactive (C-terminal, cFGF23) forms. O-glycosylation by O-glycosyl transferase N-acetylgalactosaminyltransferase 3 (ppGalNAcT3) and differential cleavage by furin have been shown to be involved in regulating the ratio of active to inactive FGF23. Elevated iFGF23 levels are observed in a number of hypophosphatemic disorders, such as X-linked, autosomal recessive, and autosomal dominant hypophosphatemic rickets, whereas low iFGF23 levels are found in the hyperphosphatemic disorder familial tumoral calcinosis/hyperphosphatemic hyperostosis syndrome. Fibrous dysplasia of bone (FD) is associated with increased total FGF23 levels (cFGF23?+?iFGF23); however, classic hypophosphatemic rickets is uncommon. Our results suggest that it can be explained by increased FGF23 cleavage leading to an increase in inactive cFGF23 relative to active iFGF23. Given the fact that FD is caused by activating mutations in the small G-protein G(s) ? that results in increased cyclic adenosine monophosphate (cAMP) levels, we postulated that there may be altered FGF23 cleavage in FD and that the mechanism may involve alterations in cAMP levels and ppGalNacT3 and furin activities. Analysis of blood specimens from patients with FD confirmed that the elevated total FGF23 levels are the result of proportionally increased cFGF23 levels, consistent with less glycosylation and enhanced cleavage by furin. Analysis of primary cell lines of normal and mutation-harboring bone marrow stromal cells (BMSCs) from patients with FD demonstrated that BMSCs harboring the causative G(s) ? mutation had higher cAMP levels, lower ppGalNAcT3, and higher furin activity. These data support the model wherein glycosylation by ppGalNAcT3 inhibits FGF23 cleavage by furin and suggest that FGF23 processing is a regulated process that controls overall FGF23 activity in FD patients. PMID:22247037

  12. 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

  13. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...description of the non-Alaskan mechanized bottom fish processing subcategory. 408.220 ...CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 ...description of the non-Alaskan mechanized bottom fish processing subcategory. The...

  14. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...description of the non-Alaskan mechanized bottom fish processing subcategory. 408.220 ...CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 ...description of the non-Alaskan mechanized bottom fish processing subcategory. The...

  15. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...description of the non-Alaskan mechanized bottom fish processing subcategory. 408.220 ...CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 ...description of the non-Alaskan mechanized bottom fish processing subcategory. The...

  16. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...description of the non-Alaskan mechanized bottom fish processing subcategory. 408.220 ...CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 ...description of the non-Alaskan mechanized bottom fish processing subcategory. The...

  17. 40 CFR 408.220 - Applicability; description of the non-Alaskan mechanized bottom fish processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...description of the non-Alaskan mechanized bottom fish processing subcategory. 408.220 ...CATEGORY Non-Alaskan Mechanized Bottom Fish Processing Subcategory § 408.220 ...description of the non-Alaskan mechanized bottom fish processing subcategory. The...

  18. Interaction of trapped ions with trapped atoms

    E-print Network

    Grier, Andrew T. (Andrew Todd)

    2011-01-01

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

  19. Computational Mechanics of Input-Output Processes: Structured Transformations and the ? -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 ? {{-}}machine. We extend computational mechanics to communication channels coupling two processes, obtaining an analogous optimal model—the ? {{-}}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.

  20. Trapped antihydrogen.

    PubMed

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

    2010-12-01

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

  1. 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.

  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. Identification of deep trap energies and influences of oxygen plasma ashing on semiconductor carrier lifetime

    NASA Astrophysics Data System (ADS)

    Koprowski, A.; Humbel, O.; Plappert, M.; Krenn, H.

    2015-03-01

    We have performed an analytical study of the effects of oxygen plasma ashing processes in semiconductor device fabrication and its impact on minority carrier lifetime in high voltage semiconductor devices. Our work includes a critical background study of life time killing mechanisms by deep traps imparted into the semiconductor by barrel plasma ashing. The Elymat technique provides the opportunity to measure lifetime and diffusion length of minority carriers and surface photo voltage (SPV) measurement was used to analyse influences of process parameters such as photoresist, time budget and positioning in the process chamber. It was shown that in microwave plasma processes the diffusion length changes severely with tempering at 200 °C, whereas RF-plasma processes show a significant process time-dependence. Batch tools in general suffer from a strong first wafer effect which could be correlated with the static electrical parameters of the semiconductor devices. The trap identities were detected by using deep level transient spectroscopy and the chemical species of the traps has been proven by inductive coupled plasma mass spectrometry. The deep-bandgap trap energies are reliable fingerprints of the chosen process parameters such as process time and of resist-influences. By microwave plasma processes intrinsic Fe and FeB-complex levels were identified and a good agreement with the SPV-measurement and electrical device characteristic was shown. RF-plasma processes impart levels attributed to Pt levels and an additional level, which could be identified as a trap level probably forming a complex of Pt and H.

  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. 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.

  6. 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

  7. 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.

  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. 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

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

    PubMed Central

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

    2012-01-01

    Bovine CD38/NAD+glycohydrolase (bCD38) catalyses the hydrolysis of NAD+ into nicotinamide and ADP-ribose and the formation of cyclic ADP-ribose (cADPR). We solved the crystal structures of the mono N-glycosylated forms of the ecto-domain of bCD38 or the catalytic residue mutant Glu218Gln in their apo state or bound to aFNAD or rFNAD, two 2?-fluorinated analogs of NAD+. Both compounds behave as mechanism-based inhibitors, allowing the trapping of a reaction intermediate covalently linked to Glu218. Compared to the non-covalent (Michaelis) complex, the ligands adopt a more folded conformation in the covalent complexes. Altogether these crystallographic snapshots along the reaction pathway reveal the drastic conformational rearrangements undergone by the ligand during catalysis with the repositioning of its adenine ring from a solvent-exposed position stacked against Trp168 to a more buried position stacked against Trp181. This adenine flipping between conserved tryptophans is a prerequisite for the proper positioning of the N1 of the adenine ring to perform the nucleophilic attack on the C1? of the ribofuranoside ring ultimately yielding cADPR. In all structures, however, the adenine ring adopts the most thermodynamically favorable anti conformation, explaining why cyclization, which requires a syn conformation, remains a rare alternate event in the reactions catalyzed by bCD38 (cADPR represents only 1% of the reaction products). In the Michaelis complex, the substrate is bound in a constrained conformation; the enzyme uses this ground-state destabilization, in addition to a hydrophobic environment and desolvation of the nicotinamide-ribosyl bond, to destabilize the scissile bond leading to the formation of a ribooxocarbenium ion intermediate. The Glu218 side chain stabilizes this reaction intermediate and plays another important role during catalysis by polarizing the 2?-OH of the substrate NAD+. Based on our structural analysis and data on active site mutants, we propose a detailed analysis of the catalytic mechanism. PMID:22529956

  12. 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)

  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. 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

  15. Stratigraphy, depositional history, and trapping mechanisms of Lone Tree Creek and Lodgepole Creek oil fields, Lower Cretaceous Fall River formation, Powder River Basin, Wyoming

    SciTech Connect

    Gustason, E.R.; Ryer, T.A.

    1985-05-01

    Stratigraphically trapped accumulations of oil in the Lone Tree Creek and Lodgepole Creek fields occur within and just updip from a fluvial meander belt within the Fall River Formation. The meander belt can be mapped north-to-south over a distance of at least 100 mi (161 km) in the eastern part of the Powder River basin. The northern part of the meander belt contains the oil fields of the Coyote Creek-Miller Creek trend; the southern part contains only the relatively small Lone Tree Creek and Lodgepole Creek fields. These small fields are of considerable interest, as they display a style of stratigraphic trapping of hydrocarbons not observed in the prolific Coyote Creek-Miller Creek trend. The stratigraphic traps of the Coyote Creek-Miller Creek trend occur at updip facing convexities along the eastern edge of the meander belt, with abandonment clay plugs serving as lateral permeability barriers to hydrocarbon migration. Oil has been produced in part of the Lone Tree Creek field from a similar trap. The remaining part of Lone Tree Creek field and Lodgepole creek field produce from stratigraphic traps formed by lateral pinch-outs of delta-front sandstone bodies. These traps are situated updip from and apparently in continuity with the meander-belt deposits, indicating that they may have been charged with hydrocarbons that found their way through the clay-plug barriers along the margin of the meander belt. Similar, undiscovered traps may exist updip from Fall River meander belts elsewhere in the basin.

  16. 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.

  17. TRAP1-dependent regulation of p70S6K is involved in the attenuation of protein synthesis and cell migration: relevance in human colorectal tumors.

    PubMed

    Matassa, Danilo Swann; Agliarulo, Ilenia; Amoroso, Maria Rosaria; Maddalena, Francesca; Sepe, Leandra; Ferrari, Maria Carla; Sagar, Vinay; D'Amico, Silvia; Loreni, Fabrizio; Paolella, Giovanni; Landriscina, Matteo; Esposito, Franca

    2014-12-01

    TNF receptor-associated protein 1 (TRAP1) is an HSP90 chaperone involved in stress protection and apoptosis in mitochondrial and extramitochondrial compartments. Remarkably, aberrant deregulation of TRAP1 function has been observed in several cancer types with potential new opportunities for therapeutic intervention in humans. Although previous studies by our group identified novel roles of TRAP1 in quality control of mitochondria-destined proteins through the attenuation of protein synthesis, molecular mechanisms are still largely unknown. To shed further light on the signaling pathways regulated by TRAP1 in the attenuation of protein synthesis, this study demonstrates that the entire pathway of cap-mediated translation is activated in cells following TRAP1 interference: consistently, expression and consequent phosphorylation of p70S6K and RSK1, two translation activating kinases, are increased upon TRAP1 silencing. Furthermore, we show that these regulatory functions affect the response to translational stress and cell migration in wound healing assays, processes involving both kinases. Notably, the regulatory mechanisms controlled by TRAP1 are conserved in colorectal cancer tissues, since an inverse correlation between TRAP1 and p70S6K expression is found in tumor tissues, thereby supporting the relevant role of TRAP1 translational regulation in vivo. Taken as a whole, these new findings candidate TRAP1 network for new anti-cancer strategies aimed at targeting the translational/quality control machinery of tumor cells. PMID:24962791

  18. Depositional environments, sequence stratigraphy, and trapping mechanisms of Fall River Formation in Donkey Creek and Coyote Creek oil fields, Powder River basin, Wyoming

    SciTech Connect

    Knox, P.R. )

    1989-09-01

    Donkey Creek and Coyote Creek fields contain combined reserves of approximately 35 million bbl of oil and are within a trend of fields on the eastern flank of the Powder River basin that totals over 100 million bbl of reserves. The principal producing formation is the Lower Cretaceous Fall River Sandstone. A study of 45 cores and 248 logs from the three pools in the Donkey Creek and Coyote fields has shown that the Fall River is composed of three progradational deltaic units deposited during a period of rising relative sea level. These are locally eroded and are filled by a fluvial point-bar complex deposited following a lowering of relative sea level. Four important depositional facies have been recognized: the delta-front and distributary-channel sandstone of the highstand deltaic sequence and the point-bar sandstone and channel-abandonment of the lowstand fluvial sequence. Stratigraphic traps in Coyote Creek and south Donkey Creek pools are the result of permeable (250 md) point-bar sandstone (250 bbl oil/day ip) bounded updip by impermeable (0.1 md) channel abandonment mudstone. Most of the oil in the central Donkey Creek pool is produced from permeable (76 md) distributary-channel sandstone (150 bbl oil/day ip), which is restricted to the western flank of a structural nose. Lesser production, on the crest and upper western flank of the structure, is obtained from the less permeable (2.8 md) delta-front sandstone (50 bbl oil/day ip). Production is possibly limited to the crest and western flank by hydrodynamic processes.

  19. 42 CFR 433.116 - FFP for operation of mechanized claims processing and information retrieval systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... and information retrieval systems. 433.116 Section 433.116 Public Health CENTERS FOR MEDICARE... FISCAL ADMINISTRATION Mechanized Claims Processing and Information Retrieval Systems § 433.116 FFP for operation of mechanized claims processing and information retrieval systems. (a) Subject to paragraph (j)...

  20. 42 CFR 433.116 - FFP for operation of mechanized claims processing and information retrieval systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... and information retrieval systems. 433.116 Section 433.116 Public Health CENTERS FOR MEDICARE... FISCAL ADMINISTRATION Mechanized Claims Processing and Information Retrieval Systems § 433.116 FFP for operation of mechanized claims processing and information retrieval systems. (a) Subject to paragraph (j)...

  1. 42 CFR 433.116 - FFP for operation of mechanized claims processing and information retrieval systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... and information retrieval systems. 433.116 Section 433.116 Public Health CENTERS FOR MEDICARE... FISCAL ADMINISTRATION Mechanized Claims Processing and Information Retrieval Systems § 433.116 FFP for operation of mechanized claims processing and information retrieval systems. (a) Subject to paragraph (j)...

  2. 42 CFR 433.116 - FFP for operation of mechanized claims processing and information retrieval systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... and information retrieval systems. 433.116 Section 433.116 Public Health CENTERS FOR MEDICARE... FISCAL ADMINISTRATION Mechanized Claims Processing and Information Retrieval Systems § 433.116 FFP for operation of mechanized claims processing and information retrieval systems. (a) Subject to paragraph (j)...

  3. 42 CFR 433.116 - FFP for operation of mechanized claims processing and information retrieval systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... FISCAL ADMINISTRATION Mechanized Claims Processing and Information Retrieval Systems § 433.116 FFP for operation of mechanized claims processing and information retrieval systems. (a) Subject to 42 CFR 433.113(c... and information retrieval systems. 433.116 Section 433.116 Public Health CENTERS FOR...

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

    E-print Network

    Wei, Qiuming

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

  5. 9 CFR 318.18 - Handling of certain material for mechanical processing.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 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...

  6. 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...

  7. On biodiversity conservation and poverty traps.

    PubMed

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

    2011-08-23

    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

  8. 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

  9. 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.

  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. 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.

  12. 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.

  13. 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.

  14. 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

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

    DOEpatents

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

    1999-01-01

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

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

    DOEpatents

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

    2000-01-01

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

  17. 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.

  18. 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.

  19. 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

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

    PubMed

    Cenis, José L; Madurga, Rodrigo; Aznar-Cervantes, Salvador D; Lozano-Pérez, A Abel; Marí-Buyé, Núria; Meseguer-Olmo, Luis; Plaza, Gustavo R; Guinea, Gustavo V; Elices, Manuel; Del Pozo, Francisco; Pérez-Rigueiro, José

    2015-11-17

    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. ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS: Generation of Arbitrary Pure States for Three-dimensional Motion of a Trapped Ion

    NASA Astrophysics Data System (ADS)

    Li, Da-Chuang; Wang, Xian-Ping; Dong, Ping; Yang, Ming; Cao, Zhuo-Liang

    2010-04-01

    In this paper, we propose a scheme for generating an arbitrary three-dimensional pure state of vibrational motion of a trapped ion. Our scheme is based on a sequence of laser pulses, which are tuned to the appropriate vibrational sidebands with respect to the appropriate electronic transition.

  2. 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.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Ghirardi, GianCarlo

    2015-07-01

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

  5. 45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... claims processing and information retrieval systems; definitions. Section 205.35 through 205.38 contain...: (a) A mechanized claims processing and information retrieval system, hereafter referred to as an automated application processing and information retrieval system (APIRS), or the system, means a system...

  6. 45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... claims processing and information retrieval systems; definitions. Section 205.35 through 205.38 contain...: (a) A mechanized claims processing and information retrieval system, hereafter referred to as an automated application processing and information retrieval system (APIRS), or the system, means a system...

  7. 45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... claims processing and information retrieval systems; definitions. Section 205.35 through 205.38 contain...: (a) A mechanized claims processing and information retrieval system, hereafter referred to as an automated application processing and information retrieval system (APIRS), or the system, means a system...

  8. 45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... claims processing and information retrieval systems; definitions. Section 205.35 through 205.38 contain...: (a) A mechanized claims processing and information retrieval system, hereafter referred to as an automated application processing and information retrieval system (APIRS), or the system, means a system...

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  11. Processed wastewater sludge for improvement of mechanical properties of concretes.

    PubMed

    Barrera-Díaz, Carlos; Martínez-Barrera, Gonzalo; Gencel, Osman; Bernal-Martínez, 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

  12. Atomic mechanism of vitrification process in simple monatomic nanoparticles *

    NASA Astrophysics Data System (ADS)

    Hoang, V. V.

    2011-02-01

    Glass formation in simple monatomic nanoparticles has been studied by molecular dynamics simulations in spherical model with a free surface. Models have been obtained by cooling from the melt toward glassy state. Atomic mechanism of glass formation was monitored via spatio-temporal arrangement of solid-like and liquid-like atoms in nanoparticles. We use Lindemann freezing-like criterion for identification of solid-like atoms which occur randomly in supercooled region. Their number grows intensively with decreasing temperature and they form clusters. Subsequently, single percolation solid-like cluster occurs at temperature above the glass transition. Glass transition occurs when atoms aggregated into this single percolation cluster are in majority in the system to form relatively rigid glassy state. Solid-like domain is forming in the center of nanoparticles and grows outward to the surface. We found temperature dependence of potential energy, mean-squared displacement (MSD) of atoms, diffusion constant, incoherent intermediate scattering function, radial distribution function (RDF), local bond-pair orders detected by Honeycutt-Andersen analysis, radial density profile and radial atomic displacement distributions in nanoparticles. We found that liquid-like atoms in models obtained below glass transition have a tendency to concentrate in the surface layer of nanoparticles. However, they do not form a purely liquid-like surface layer coated nanoparticles.

  13. Cassini observations of seasonal exospheres at Saturn's icy satellites: Source and loss processes, and role of surface cold trapping.

    NASA Astrophysics Data System (ADS)

    Teolis, B. D.; Waite, J. H.

    2012-12-01

    Cassini's Ion Neutral Mass Spectrometer (INMS) has revealed dayside sputtered exospheres of radiolytic O2 and CO2 at Rhea and Dione, seasonally modulated by polar winter adsorption and equinox desorption likely to/from the porous icy regolith surfaces of seasonally shadowed polar terrains. In this talk we review current models and understanding of the global exospheric physics: including source and loss processes, spatial structure and time evolution, and discuss topographical thermal / adsorption and diffusion modeling to estimate the amounts of locally adsorbed O2 and CO2, the regolith diffusion depth of these species, and the local spatial and time variation of adsorption. We will discuss complimentary Cassini Plasma Spectrometer (CAPS) observations also indicating a seasonal pickup ion source consistent with the exospheric neutral densities measured by INMS. The global exospheric loss through pickup ionization inferred from CAPS is consistent with known cross sections and estimated rates for the different ionization processes, i.e., charge exchange, dissociative ionization, and photo and electron impact ionization. The implied CO2 source rate is much less than that of O2 (e.g. ~0.1 and 1 ×10^22 CO2 and O2 / sec, respectively, at Rhea), but CO2 is on average more effectively retained by Rhea and Dione due to its lower volatility and greater surface stickiness, resulting in the similar measured exospheric densities of these species (INMS detections are of order 10^10 per m3 at roughly 100 km altitude). The O2 source rate is two orders of magnitude less than the ~2×10^24 / sec predicted on the basis of the estimated magnetospheric ion and electrons surface irradiation fluxes and measured O2 formation yields from irradiated laboratory water ice. We will discuss possible explanations, and implications for exospheric oxygen generation at other solar system icy satellites.

  14. Dissociating neural mechanisms of temporal sequencing and processing phonemes.

    PubMed

    Gelfand, Jenna R; Bookheimer, Susan Y

    2003-06-01

    Using fMRI, we sought to determine whether the posterior, superior portion of Broca's area performs operations on phoneme segments specifically or implements processes general to sequencing discrete units. Twelve healthy volunteers performed two sequence manipulation tasks and one matching task, using strings of syllables and hummed notes. The posterior portion of Broca's area responded specifically to the sequence manipulation tasks, independent of whether the stimuli were composed of phonemes or hummed notes. In contrast, the left supramarginal gyrus was somewhat more specific to sequencing phoneme segments. These results suggest a functional dissociation of the canonical left hemisphere language regions encompassing the "phonological loop," with the left posterior inferior frontal gyrus responding not to the sound structure of language but rather to sequential operations that may underlie the ability to form words out of dissociable elements. PMID:12797966

  15. 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.

  16. Streamer-induced transport in the presence of trapped ion modes in tokamak plasmas

    SciTech Connect

    Ghizzo, A.; Del Sarto, D.; Garbet, X.; Sarazin, Y.

    2010-09-15

    Global gyrokinetic Vlasov simulations for trapped ion modes are performed by solving a Vlasov equation averaged over the cyclotron and bounce motions of trapped ions. The distribution function, for trapped ions, is then calculated in a two-dimensional phase space, parametrized by the longitudinal action (energy) and the magnetic moment in presence of magnetic shear. The physical mechanism of the saturation processes between streamerlike structures and zonal flows in relation to the suppression of turbulent transport is discussed. The magnetic shear is identified to play a key role in the dominant streamer-induced transport regime, which exhibits a Bohm-like scaling. The interaction of streamerlike structures with plasma turbulence is shown to produce the inverse cascade that condenses onto long-wavelength trapped ion structures, on the basis on wave triad interactions.

  17. Effective Steam Trap Selection/Maintenance - Its Payback 

    E-print Network

    Garcia, E.

    1984-01-01

    In oil refineries and petrochemical plants large number of steam traps are used to discharge condensate from steam mains, tracers and process equipment. Early efforts on steam traps focused almost exclusively on their selection and sizing...

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. Additive Manufacturing of Inconel 718 using Electron Beam Melting: Processing, Post-Processing, & Mechanical Properties 

    E-print Network

    Sames, William

    2015-05-01

    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, ...

  4. A two species trap for chromium and rubidium atoms

    E-print Network

    Sven Hensler; Axel Griesmaier; Jörg Werner; Axel Görlitz; Tilman Pfau

    2004-01-20

    We realize a combined trap for bosonic chromium 52Cr and rubidium 87Rb atoms. First experiments focus on exploring a suitable loading scheme for the combined trap and on studies of new trap loss mechanisms originating from simultaneous trapping of two species. By comparing the trap loss from the 87Rb magneto-optical trap (MOT) in absence and presence of magnetically trapped ground state 52Cr atoms we determine the scattering cross section of sigma_{inelRbCr}=(5.0+-4.0)*10^{-18}m^2 for light induced inelastic collisions between the two species. Studying the trap loss from the Rb magneto-optical trap induced by the Cr cooling-laser light, the photoionization cross section of the excited 5P_{3/2} state at an ionizing wavelength of 426nm is measured to be sigma_{p}=(1.1+-0.3)*10^{-21}m^2.

  5. 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.

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

    E-print Network

    Vaina, Lucia M.

    Two mechanisms for optic flow and scale change processing of looming Brain and Vision Research Laboratory, Department of Biomedical Engineering, Boston University, Boston, MA, USAFinnegan J. Calabro Brain and Vision Research Laboratory, Department of Biomedical Engineering, Boston University, Boston, MA

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

    E-print Network

    Manga, Michael

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

  8. 40 CFR 408.30 - Applicability; description of the mechanized blue crab processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...The provisions of this subpart are applicable to discharges resulting from the processing of blue crab in which mechanical picking or separation of crab meat from the shell is utilized. [40 FR 55780, Dec. 1,...

  9. Processing and mechanical behavior of aluminium oxide microstructure composites

    NASA Astrophysics Data System (ADS)

    Pavlacka, Robert J.

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

  10. Dissociable Brain Mechanisms for Processing Social Exclusion and Rule Violation

    PubMed Central

    Bolling, Danielle Z.; Pitskel, Naomi B.; Deen, Ben; Crowley, Michael J.; McPartland, James C.; Mayes, Linda C.; Pelphrey, Kevin A.

    2010-01-01

    Social exclusion inherently involves an element of expectancy violation, in that we expect other people to follow the unwritten rule to include us in social interactions. In this functional magnetic resonance imaging (fMRI) study, we employed a unique modification of an interactive virtual ball-tossing game called “Cyberball” (Williams et al., 2000) and a novel paradigm called “Cybershape”, in which rules are broken in the absence of social exclusion, to dissociate brain regions that process social exclusion from rule violations more generally. Our Cyberball game employed an alternating block design and removed evoked responses to events when the participant was throwing the ball in inclusion to make this condition comparable to exclusion, where participants did not throw. With these modifications, we replicated prior findings of ventral anterior cingulate cortex (vACC), insula, and posterior cingulate cortex activity evoked by social exclusion relative to inclusion. We also identified exclusion-evoked activity in the hippocampi, left ventrolateral prefrontal cortex, and left middle temporal gyrus. Comparing social exclusion and rule violation revealed a functional dissociation in the active neural systems as well as differential functional connectivity with vACC. Some overlap was observed in regions differentially modulated by social exclusion and rule violation, including the vACC and lateral parietal cortex. These overlapping brain regions showed different activation during social exclusion compared to rule violation, each relative to fair play. Comparing activation patterns to social exclusion and rule violation allowed for the dissociation of brain regions involved in the experience of exclusion versus expectancy violation. PMID:20974272

  11. 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

  12. 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…

  13. Microstructure and mechanical behavior of ultrafine-grained Ni processed by different powder metallurgy methods

    E-print Network

    Gubicza, Jenõ

    and mechanical behavior of bulk UFG samples produced by different powder metal- lurgy procedures is of greatMicrostructure and mechanical behavior of ultrafine-grained Ni processed by different powder- particles.5­7 Most bottom-up methods first produce nano- powders, which need to be consolidated in a second

  14. 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 (˜1200°C, 4 min). Raman spectroscopy revealed that single-walled carbon nanotubes (SWCNTs) begin to break down at sintering temperatures above 1150°C. 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 MPa·m 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 MPa·m1/2 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.

  15. Microfabricated Ion Traps

    E-print Network

    Marcus D. Hughes; Bjoern Lekitsch; Jiddu A. Broersma; Winfried K. Hensinger

    2011-06-28

    Ion traps offer the opportunity to study fundamental quantum systems with high level of accuracy highly decoupled from the environment. Individual atomic ions can be controlled and manipulated with electric fields, cooled to the ground state of motion with laser cooling and coherently manipulated using optical and microwave radiation. Microfabricated ion traps hold the advantage of allowing for smaller trap dimensions and better scalability towards large ion trap arrays also making them a vital ingredient for next generation quantum technologies. Here we provide an introduction into the principles and operation of microfabricated ion traps. We show an overview of material and electrical considerations which are vital for the design of such trap structures. We provide guidance in how to choose the appropriate fabrication design, consider different methods for the fabrication of microfabricated ion traps and discuss previously realized structures. We also discuss the phenomenon of anomalous heating of ions within ion traps, which becomes an important factor in the miniaturization of ion traps.

  16. Trapping polar molecules in an ac trap

    SciTech Connect

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

    2006-12-15

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

  17. Seismic fault zone trapped noise

    NASA Astrophysics Data System (ADS)

    Hillers, G.; Campillo, M.; Ben-Zion, Y.; Roux, P.

    2014-07-01

    Systematic velocity contrasts across and within fault zones can lead to head and trapped waves that provide direct information on structural units that are important for many aspects of earthquake and fault mechanics. Here we construct trapped waves from the scattered seismic wavefield recorded by a fault zone array. The frequency-dependent interaction between the ambient wavefield and the fault zone environment is studied using properties of the noise correlation field. A critical frequency fc ? 0.5 Hz defines a threshold above which the in-fault scattered wavefield has increased isotropy and coherency compared to the ambient noise. The increased randomization of in-fault propagation directions produces a wavefield that is trapped in a waveguide/cavity-like structure associated with the low-velocity damage zone. Dense spatial sampling allows the resolution of a near-field focal spot, which emerges from the superposition of a collapsing, time reversed wavefront. The shape of the focal spot depends on local medium properties, and a focal spot-based fault normal distribution of wave speeds indicates a ˜50% velocity reduction consistent with estimates from a far-field travel time inversion. The arrival time pattern of a synthetic correlation field can be tuned to match properties of an observed pattern, providing a noise-based imaging tool that can complement analyses of trapped ballistic waves. The results can have wide applicability for investigating the internal properties of fault damage zones, because mechanisms controlling the emergence of trapped noise have less limitations compared to trapped ballistic waves.

  18. 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.

  19. 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.

  20. The mechanism of thermally transferred optically stimulated luminescence in quartz

    NASA Astrophysics Data System (ADS)

    Adamiec, G.; Bailey, R. M.; Wang, X. L.; Wintle, A. G.

    2008-07-01

    In this paper we assess two mechanisms for the production of the thermally transferred optically stimulated luminescence (TT-OSL) signal in quartz when all stimulation is carried out at 125 °C. One mechanism is based on the double transfer process previously put forward for OSL recuperation following storage at room temperature. In this mechanism, electrons from the trap giving rise to the fast OSL component are released by optical stimulation and some are transferred into a refuge trap via the conduction band; these electrons are then released from the refuge trap by a thermal treatment and some are retrapped in the trap responsible for the fast OSL component. The other mechanism is based on a single transfer process in which electrons are transferred by thermal treatment from a light-sensitive trap via the conduction band to the trap that gives rise to the fast component of the OSL signal, this trap having been emptied by the initial optical stimulation. The analysis of the measured OSL and TT-OSL decay curves suggest that the two signals are derived from the same traps and are dominated by the fast OSL component. The experimental data presented support the hypothesis that the original source of the electrons that are thermally transferred is a trap that is less light sensitive than that giving rise to the fast OSL, but one that has similar thermal stability. Thus, a single transfer mechanism explains the production of the TT-OSL signal observed for stimulation above 120 °C when the 110 °C TL trap is kept empty.

  1. 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…

  2. Vortex creation during magnetic trap manipulations of spinor Bose-Einstein condensates

    SciTech Connect

    Itin, A. P.; Morishita, T.; Satoh, M.; Watanabe, S.; Tolstikhin, O. I.

    2006-06-15

    We investigate several mechanisms of vortex creation during splitting of a spinor Bose-Einstein condensate (BEC) in a magnetic double-well trap controlled by a pair of current carrying wires and bias magnetic fields. Our study is motivated by a recent MIT experiment on splitting BECs with a similar trap [Y. Shin et al., Phys. Rev. A 72, 021604 (2005)], where an unexpected fork-like structure appeared in the interference fringes indicating the presence of a singly quantized vortex in one of the interfering condensates. It is well known that in a spin-1 BEC in a quadrupole trap, a doubly quantized vortex is topologically produced by a 'slow' reversal of bias magnetic field B{sub z}. Since in the experiment a doubly quantized vortex had never been seen, Shin et al. ruled out the topological mechanism and concentrated on the nonadiabatic mechanical mechanism for explanation of the vortex creation. We find, however, that in the magnetic trap considered both mechanisms are possible: singly quantized vortices can be formed in a spin-1 BEC topologically (for example, during the magnetic field switching-off process). We therefore provide a possible alternative explanation for the interference patterns observed in the experiment. We also present a numerical example of creation of singly quantized vortices due to 'fast' splitting; i.e., by a dynamical (nonadiabatic) mechanism.

  3. Superconducting microfabricated ion traps

    E-print Network

    Wang, Shannon Xuanyue

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

  4. Evaluating Steam Trap Performance 

    E-print Network

    Fuller, N. Y.

    1986-01-01

    TRAP PERFORMANCE Noel Y Fuller, P.E. Holston Defense Corporation Kingsport, Tennessee ABSTRACT Laboratory tests were conducted on several types of steam traps at Holston Defense Corporation in Kingsport, Tennessee. Data from these tests...

  5. 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

  6. A trapped field of 17.6 T in melt-processed, bulk Gd-Ba-Cu-O reinforced with shrink-fit steel

    NASA Astrophysics Data System (ADS)

    Durrell, J. H.; Dennis, A. R.; Jaroszynski, J.; Ainslie, M. D.; Palmer, K. G. B.; Shi, Y.-H.; Campbell, A. M.; Hull, J.; Strasik, M.; Hellstrom, E. E.; Cardwell, D. A.

    2014-08-01

    The ability of large-grain (RE)Ba2Cu3O7-? ((RE)BCO; RE = rare earth) bulk superconductors to trap magnetic fields is determined by their critical current. With high trapped fields, however, bulk samples are subject to a relatively large Lorentz force, and their performance is limited primarily by their tensile strength. Consequently, sample reinforcement is the key to performance improvement in these technologically important materials. In this work, we report a trapped field of 17.6 T, the largest reported to date, in a stack of two silver-doped GdBCO superconducting bulk samples, each 25 mm in diameter, fabricated by top-seeded melt growth and reinforced with shrink-fit stainless steel. This sample preparation technique has the advantage of being relatively straightforward and inexpensive to implement, and offers the prospect of easy access to portable, high magnetic fields without any requirement for a sustaining current source.

  7. 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.

  8. Development of monolithic 3D ion traps microfabricated

    E-print Network

    Hensinger, Winfried

    Development of monolithic 3D ion traps microfabricated using SiO -on-Si2 Guido Wilpers, Patrick See surface traps [1,2], 2) 3D Au coated alumina [3-5],3) 3D degenerate Silicon [6], 4) monolithic 3D Ga. The design offers * manufacture based on planar processing to create a 3D trap, * a monolithic design

  9. 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...

  10. 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.

  11. Coherent Manipulation of Holes in Dipole Trap Arrays

    E-print Network

    Benseny, Albert; Bagudà, Joan; Corbalán, Ramón; Picón, Antonio; Roso, Luis; Birkl, Gerhard; Mompart, Jordi

    2009-01-01

    We investigate single-occupancy dipole trap arrays loaded with a gas of either fermions or bosons presenting some isolated defects consisting in empty sites, i.e., holes. The tunneling interaction between neighboring sites is used to prepare multi-site dark states for the holes allowing for the coherent manipulation of their external degrees of freedom. By means of an ab initio integration of the Schr\\"odinger equation, we investigate the adiabatic transport of holes between the two extreme traps of a triple-well potential as well as the preparation of a defect-free trap domain. Furthermore, a quantum-trajectory approach based on the de Broglie--Bohm formulation of quantum mechanics is used to get detailed physical insight into the transport process. We extend the previous results to a single hole in a dipole trap array of arbitrary length by means of the Hubbard model, where hole creation and annihilation operators are introduced. Finally, we discuss the use of the hole for the construction of a coherent sin...

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

    PubMed Central

    Hampson, Sarah E.

    2011-01-01

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

  13. 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.

  14. A Small Molecule That Switches a Ubiquitin Ligase From a Processive to a Distributive Enzymatic Mechanism.

    PubMed

    Kathman, Stefan G; Span, Ingrid; Smith, Aaron T; Xu, Ziyang; Zhan, Jennifer; Rosenzweig, Amy C; Statsyuk, Alexander V

    2015-10-01

    E3 ligases are genetically implicated in many human diseases, yet E3 enzyme mechanisms are not fully understood, and there is a strong need for pharmacological probes of E3s. We report the discovery that the HECT E3 Nedd4-1 is a processive enzyme and that disruption of its processivity by biochemical mutations or small molecules switches Nedd4-1 from a processive to a distributive mechanism of polyubiquitin chain synthesis. Furthermore, we discovered and structurally characterized the first covalent inhibitor of Nedd4-1, which switches Nedd4-1 from a processive to a distributive mechanism. To visualize the binding mode of the Nedd4-1 inhibitor, we used X-ray crystallography and solved the first structure of a Nedd4-1 family ligase bound to an inhibitor. Importantly, our study shows that processive Nedd4-1, but not the distributive Nedd4-1:inhibitor complex, is able to synthesize polyubiquitin chains on the substrate in the presence of the deubiquitinating enzyme USP8. Therefore, inhibition of E3 ligase processivity is a viable strategy to design E3 inhibitors. Our study provides fundamental insights into the HECT E3 mechanism and uncovers a novel class of HECT E3 inhibitors. PMID:26371805

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

    PubMed

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

    2015-09-01

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

  16. A Small Molecule That Switches a Ubiquitin Ligase From a Processive to a Distributive Enzymatic Mechanism

    PubMed Central

    Kathman, Stefan G.; Span, Ingrid; Smith, Aaron T.; Xu, Ziyang; Zhan, Jennifer; Rosenzweig, Amy C.; Statsyuk, Alexander V.

    2015-01-01

    E3 ligases are genetically implicated in many human diseases, yet E3 enzyme mechanisms are not fully understood, and there is a strong need for pharmacological probes of E3s. We report the discovery that the HECT E3 Nedd4-1 is a processive enzyme and that disruption of its processivity by biochemical mutations or small molecules switches Nedd4-1 from a processive to a distributive mechanism of polyubiquitin chain synthesis. Furthermore, we discovered and structurally characterized the first covalent inhibitor of Nedd4-1, which switches Nedd4-1 from a processive to a distributive mechanism. To visualize the binding mode of the Nedd4-1 inhibitor, we used X-ray crystallography and solved the first structure of a Nedd4-1 family ligase bound to an inhibitor. Importantly, our study shows that processive Nedd4-1, but not the distributive Nedd4-1:inhibitor complex, is able to synthesize polyubiquitin chains on the substrate in the presence of the deubiquitinating enzyme USP8. Therefore, inhibition of E3 ligase processivity is a viable strategy to design E3 inhibitors. Our study provides fundamental insights into the HECT E3 mechanism and uncovers a novel class of HECT E3 inhibitors. PMID:26371805

  17. 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.

  18. 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.

  19. pH-Based Regulation of Hydrogel Mechanical Properties Through Mussel-Inspired Chemistry and Processing.

    PubMed

    Barrett, Devin G; Fullenkamp, Dominic E; He, Lihong; Holten-Andersen, Niels; Lee, Ka Yee C; Messersmith, Phillip B

    2013-03-01

    The mechanical holdfast of the mussel, the byssus, is processed at acidic pH yet functions at alkaline pH. Byssi are enriched in Fe(3+) and catechol-containing proteins, species with chemical interactions that vary widely over the pH range of byssal processing. Currently, the link between pH, Fe(3+)-catechol reactions, and mechanical function are poorly understood. Herein, we describe how pH influences the mechanical performance of materials formed by reacting synthetic catechol polymers with Fe(3+). Processing Fe(3+)-catechol polymer materials through a mussel-mimetic acidic-to-alkaline pH change leads to mechanically tough materials based on a covalent network fortified by sacrificial Fe(3+)-catechol coordination bonds. Our findings offer the first direct evidence of Fe(3+)-induced covalent cross-linking of catechol polymers, reveal additional insight into the pH dependence and mechanical role of Fe(3+)- catechol interactions in mussel byssi, and illustrate the wide range of physical properties accessible in synthetic materials through mimicry of mussel protein chemistry and processing. PMID:23483665

  20. pH-Based Regulation of Hydrogel Mechanical Properties Through Mussel-Inspired Chemistry and Processing

    PubMed Central

    Barrett, Devin G.; Fullenkamp, Dominic E.; He, Lihong; Holten-Andersen, Niels; Lee, Ka Yee C.; Messersmith, Phillip B.

    2013-01-01

    The mechanical holdfast of the mussel, the byssus, is processed at acidic pH yet functions at alkaline pH. Byssi are enriched in Fe3+ and catechol-containing proteins, species with chemical interactions that vary widely over the pH range of byssal processing. Currently, the link between pH, Fe3+-catechol reactions, and mechanical function are poorly understood. Herein, we describe how pH influences the mechanical performance of materials formed by reacting synthetic catechol polymers with Fe3+. Processing Fe3+-catechol polymer materials through a mussel-mimetic acidic-to-alkaline pH change leads to mechanically tough materials based on a covalent network fortified by sacrificial Fe3+-catechol coordination bonds. Our findings offer the first direct evidence of Fe3+-induced covalent cross-linking of catechol polymers, reveal additional insight into the pH dependence and mechanical role of Fe3+- catechol interactions in mussel byssi, and illustrate the wide range of physical properties accessible in synthetic materials through mimicry of mussel protein chemistry and processing. PMID:23483665

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

    SciTech Connect

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

    1996-07-01

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

  2. Mechanical Properties of Mg2Si/Mg Composites via Powder Metallurgy Process

    NASA Astrophysics Data System (ADS)

    Muramatsu, Hiroshi; Kondoh, Katsuyoshi; Yuasa, Eiji; Aizawa, Tatsuhiko

    The mechanical properties of the Mg2Si/Mg composites solid-state synthesized from the mixed Mg-Si powders have been investigated. The macro-hardness (HRE) and the tensile strength of the composites increase with increasing the Si content and decreasing the Si size. The particle size of the synthesized Mg2Si depends on the initial Si size; the mechanical properties of the Mg2Si/Mg composite are remarkably improved by using fine Si particles or by decreasing the grain size of Mg matrix grains when the powder mixture was prepared via bulk mechanical alloying process.

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

    PubMed Central

    2014-01-01

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

  4. 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

  5. ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS: Preparation of Macroscopic Quantum-Interference States for a Collection of Trapped Ions Via a Single Geometric Operation

    NASA Astrophysics Data System (ADS)

    Lin, Li-Hua

    2010-05-01

    We describe a scheme for the generation of macroscopic quantum-interference states for a collection of trapped ions by a single geometric phase operation. In the scheme the vibrational mode is displaced along a circle with the radius proportional to the number of ions in a certain ground electronic state. For a given interaction time, the vibrational mode returns to the original state, and the ionic system acquires a geometric phase proportional to the area of the circle, evolving from a coherent state to a superposition of two coherent states. The ions undergo no electronic transitions during the operation. Taking advantage of the inherent fault-tolerant feature of the geometric operation, our scheme is robust against decoherence.

  6. Poly-Electrophilic Sesquiterpene Lactones from Vernonia amygdalina: New Members and Differences in Their Mechanism of Thiol Trapping and in Bioactivity.

    PubMed

    Sinisi, Annamaria; Millán, Estrella; Abay, Solomon M; Habluetzel, Annette; Appendino, Giovanni; Muñoz, Eduardo; Taglialatela-Scafati, Orazio

    2015-07-24

    In addition to known compounds, the leaves of Vernonia amygdalina afforded the new sesquiterpene lactones 14-O-methylvernolide (2), 3'-deoxyvernodalol (6), and vernomygdalin (8). These and related compounds were evaluated for modulation of a series of thiol trapping-sensitive transcription factors (NF-?B, STAT3, and Nrf2), involved in the maintenance of the chronic inflammatory condition typical of human degenerative diseases. Vernolide (1) emerged as a potent inhibitor of STAT3 and NF-?B and showed cytostatic activity toward the prostate cancer cell line DU45, arresting the cell cycle at the S phase. The exomethylene lactones are characterized by multiple Michael acceptor sites, as exemplified by vernolide (1) and vernodalol (5). By using the nuclear magnetic resonance-based cysteamine assay, the most reactive thiophilic site could be identified in both compounds, and competitive experiments qualified vernolide (1) as being more thiophilic than vernodalol (5), in agreement with the results of the pharmacological assays. PMID:26115003

  7. 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.

  8. The role of trapped neutrino in dense stelllar matter and kaon condensation

    E-print Network

    R. Dutta

    1998-12-21

    We investigate the effect of neutrino trapping on kaon condensation process and Equation of State (EOS) in a newly formed neutron star which is less than several seconds old. Using nonlinear relativistic mean field model, we find that the presence of neutrino shifts the threshold for kaon condensation and muon production to much higher density. We also studied the energy density and pressure of the syst under trapped neutrino condition and found that it stiffens the EOS of the system which may be responsible for the delayed exploision mechanism of supernovae.

  9. Coherent generation of EPR-entangled light pulses mediated by a single trapped atom

    E-print Network

    Giovanna Morigi; Jürgen Eschner; Stefano Mancini; David Vitali

    2005-12-23

    We show that a single, trapped, laser-driven atom in a high-finesse optical cavity allows for the quantum-coherent generation of entangled light pulses on demand. Schemes for generating simultaneous and temporally separated pulse pairs are proposed. The mechanical effect of the laser excitation on the quantum motion of the cold trapped atom mediates the entangling interaction between two cavity modes and between the two subsequent pulses, respectively. The entanglement is of EPR-type, and its degree can be controlled through external parameters. At the end of the generation process the atom is decorrelated from the light field. Possible experimental implementations of the proposals are discussed.

  10. 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.

  11. 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.

  12. Microstructure and mechanical properties of 7075 aluminum alloy nanostructured composites processed by mechanical milling and indirect hot extrusion

    SciTech Connect

    Flores-Campos, R.; Estrada-Guel, I.; Miki-Yoshida, M.; Martinez-Sanchez, R.; Herrera-Ramirez, J.M.

    2012-01-15

    Nanostructured composites of 7075 aluminum alloy and carbon coated silver nanoparticles were produced by mechanical milling and indirect hot extrusion. The milling products were obtained in a high energy SPEX ball mill, and then were compacted by uniaxial load and pressure-less sintered under argon atmosphere. Finally, the sintered product was hot extruded. Carbon coated silver nanoparticles were well distributed in the matrix of the extruded material. Tensile tests were carried out to corroborate the hypothesis that second phase particles, well dispersed in the matrix, improve the strength of the material. High resolution transmission electron microscopy was employed to locate and make sure that the silver nanoparticles were homogeneously and finely dispersed. Highlights: Black-Right-Pointing-Pointer 7075 Al nanostructured composites can be produced by mechanical milling. Black-Right-Pointing-Pointer Carbon coated silver nanoparticles are well dispersed into aluminum matrix. Black-Right-Pointing-Pointer Ductile Ag-C NP's improve the mechanical properties of the 7075 Al-alloy. Black-Right-Pointing-Pointer Ag-C NP's content has an important effect in the particle and crystallite size. Black-Right-Pointing-Pointer Ag-C NP's keep their morphology after milling and conformation processes.

  13. Single trap dynamics in electrolyte-gated Si-nanowire field effect transistors

    SciTech Connect

    Pud, S.; Li, J.; Offenhäusser, 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.

  14. Influence of vibronic coupling on band structure and exciton self-trapping in ?-perylene.

    PubMed

    West, Brantley A; Womick, Jordan M; McNeil, L E; Tan, Ke Jie; Moran, Andrew M

    2011-05-12

    Exciton sizes influence transport processes and spectroscopic phenomena in molecular aggregates and crystals. Thermally driven nuclear motion generally localizes electronic states in equilibrium systems. Exciton sizes also undergo dynamic changes caused by nonequilibrium relaxation in the lattice structure local to the photoexcitations (i.e., self-trapping). The ?-phase of crystalline perylene is particularly well-suited for fundamental studies of exciton self-trapping mechanisms. It is generally agreed that a subpicosecond self-trapping process in ?-perylene localizes photoexcited excitons onto pairs of closely spaced molecules (i.e., dimers), which then relax through excimer emission. Here, electronic relaxation dynamics in ?-perylene single crystals are investigated using a variety of nonlinear optical spectroscopies in conjunction with a Frenkel exciton model. Linear absorption and photon echo spectroscopies suggest that excitons are delocalized over less than four unit cells (16 molecules) at 78 K prior to self-trapping. Stimulated Raman spectroscopies conducted on and off electronic resonance reveal significant vibronic coupling in a mode at 104 cm(-1), which corresponds to the displacement between perylene molecules comprising a dimer. Strong vibronic coupling in this mode suggests that motion along the interdimer axis is instrumental in driving the self-trapping process. The results are discussed in the context of our recent study of tetracene and rubrene single crystals in which similar experiments and models were employed. PMID:20806944

  15. 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, 5523–5527 (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.

  16. Modeling of the effect of intentionally introduced traps on hole transport in single-crystal rubrene

    NASA Astrophysics Data System (ADS)

    Dacuña, 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.

  17. 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

  18. 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

  19. 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

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

    SciTech Connect

    Edincliler, Ayse; Baykal, Goekhan; Saygili, Altug

    2010-06-15

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

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

    SciTech Connect

    Meloni, Paola; Laboratorio per lo studio dei Materiali 'Colle di Bonaria', Universita degli Studi di Cagliari, via Ravenna, I-09100 Cagliari ; Carcangiu, Gianfranco; Istituto di Geologia Ambientale e Geoingegneria , CNR, piazza d'Armi, I-09123 Cagliari ; Delogu, Francesco

    2012-01-15

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

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  6. Molecular and neural mechanisms of sex pheromone reception and processing in the silkmoth Bombyx mori

    PubMed Central

    Sakurai, Takeshi; Namiki, Shigehiro; Kanzaki, Ryohei

    2014-01-01

    Male moths locate their mates using species-specific sex pheromones emitted by conspecific females. One striking feature of sex pheromone recognition in males is the high degree of specificity and sensitivity at all levels, from the primary sensory processes to behavior. The silkmoth Bombyx mori is an excellent model insect in which to decipher the underlying mechanisms of sex pheromone recognition due to its simple sex pheromone communication system, where a single pheromone component, bombykol, elicits the full sexual behavior of male moths. Various technical advancements that cover all levels of analysis from molecular to behavioral also allow the systematic analysis of pheromone recognition mechanisms. Sex pheromone signals are detected by pheromone receptors expressed in olfactory receptor neurons in the pheromone-sensitive sensilla trichodea on male antennae. The signals are transmitted to the first olfactory processing center, the antennal lobe (AL), and then are processed further in the higher centers (mushroom body and lateral protocerebrum) to elicit orientation behavior toward females. In recent years, significant progress has been made elucidating the molecular mechanisms underlying the detection of sex pheromones. In addition, extensive studies of the AL and higher centers have provided insights into the neural basis of pheromone processing in the silkmoth brain. This review describes these latest advances, and discusses what these advances have revealed about the mechanisms underlying the specific and sensitive recognition of sex pheromones in the silkmoth. PMID:24744736

  7. The role of thermal and mechanical processes in the formation of the Ross Sea summer polynya

    E-print Network

    Holland, David

    The role of thermal and mechanical processes in the formation of the Ross Sea summer polynya Tasha the model control run agree favorably with satellite microwave imagery of sea ice. Model sensitivity studies polynya. Citation: Reddy, T. E., K. R. Arrigo, and D. M. Holland (2007), The role of thermal

  8. Rheological and mechanical properties of polyamide 6 modified by electron-beam initiated mediation process

    NASA Astrophysics Data System (ADS)

    Shin, Boo Young; Kim, Jae Hong

    2015-07-01

    Polyamide (PA6) has been modified by electron-beam initiated mediator process to improve drawbacks of PA6. Glycidyl methacrylate (GMA) was chosen as a reactive mediator for modification process of PA6. The mixture of the PA6 and GMA was prepared by using a twin-screw extruder, and then the mixture was exposed to electron-beam irradiation at various doses at room temperature. The modified PA6 were characterized by observing rheological and mechanical properties and compared virgin PA6. Thermal properties, water absorption, and gel fraction were also investigated. Tight gel was not found even when PA6 was irradiated at 200 kGy. Complex viscosity and storage modulus of PA6 were remarkably increased by electron-beam irradiation with medium of GMA. Maximum increase in complex viscosity was 75 times higher than virgin PA6 at 0.1 rad/s when it was irradiated at 200 kGy with the GMA. Mechanical properties were also improved without scarifying of processability. The reaction mechanisms for the mediation process with the reactive mediator of GMA were estimated to elucidate the cause of significantly enhanced rheological and mechanical properties without loss of thermoplasticity.

  9. Effect of processing conditions on microstructure and mechanical behaviour of metals sintered from nanopowders

    E-print Network

    Gubicza, Jenõ

    that also decreased the ductility. The reduced time and temperature in Spark Plasma Sintering compared was consolidated by Hot Isostatic Pressing (HIP) or Spark Plasma Sintering (SPS) method. Before HIPEffect of processing conditions on microstructure and mechanical behaviour of metals sintered from

  10. 45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... State plan requirements for an automated statewide management information system, conditions for FFP and... produce utilization and management information about such aid and services as required by the single State... 45 Public Welfare 2 2010-10-01 2010-10-01 false Mechanized claims processing and...

  11. Mechanical Behaviour of Conventional Materials at Experimental Conditions of Deep Drawing Technological Process

    NASA Astrophysics Data System (ADS)

    Nikolov, N.; Pashkouleva, D.; Kavardzhikov, V.

    2012-09-01

    The paper deals with experimental investigations on the mechanical behaviour of body-centred-cubic (BCC) and face-centred-cubic (FCC)-conventionally structured sheet metalic-metalic materials under stress-strain conditions of a deep drawing process determined by a coefficient close to the limiting one for Steel 08 and punch diameter of 50 mm. The mechanical characteristics of the investigated materials are identified by one-dimensional tension tests. The materials' responses, as results of identical loading conditions, are described by the change of blank sizes and characteristics of the forming processes. The chosen deformation path ensures obtaining a qualitative steel piece and leads to failures of aluminium and brass blanks. The reported results could be useful for investigations and predictions of the mechanical responses of such type metallic structures applying microscopic instrumented observations and numerical simulations.

  12. 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.

  13. Microstructural evolution and mechanical properties of a copper-zirconium alloy processed by severe plastic deformation

    NASA Astrophysics Data System (ADS)

    Wongsa-Ngam, Jittraporn

    A copper alloy, Cu-0.1% Zr, has been processed at room temperature by different techniques of severe plastic deformation (SPD), namely equal-channel angular pressing (ECAP), high-pressure torsion (HPT) and a combination of both processing (ECAP + HPT). The experiments were conducted to evaluate the microstructural evolution and mechanical properties for each of the processed and their combination. A transmission electron microscopy (TEM) and an electron backscatter diffraction (EBSD) techniques were employed to measure the microstructural features, grain size distributions and the distribution of the misorientation angles. The mechanical properties of the processed samples were examined and compared both at a room temperature using microhardness measurements and at an elevated temperature using tensile testing. Using TEM and EBSD techniques, it is demonstrated that these three SPD procedures have a potential for producing an ultrafine-grain structure containing reasonably equiaxed grains with high-angle boundary misorientations. However, microstructures are refined in different level depending on the processing operation. The grain refinement mechanisms are primarily governed by dislocation activities. Microhardness distribution of the strained samples shows that there is a non-uniform of this distribution in the early stages of deformation where the lower hardness values were measured near the bottom of samples for ECAP and at the central region for HPT. This inhomogeneity is gradual decreased with increasing imposed strain and ultimately the microhardness distribution is reasonably homogeneous when the sufficient strain is subjected to the sample. The tensile results demonstrate that the samples after SPD processing exhibit superior mechanical properties with the combination of high strength and ductility compared to the as-received materials where the maximum elongation to failure of ˜240% at 723 K using a strain rate of 1.0 x 10 -4 s-1 is achieved in a sample processed by HPT. This elongation however does not fulfilled the requirements for true superplastic flow where the measured elongation in tension should be at least 400%.

  14. Modeling the coupled mechanics, transport, and growth processes in collagen tissues.

    SciTech Connect

    Holdych, David J.; Nguyen, Thao D.; Klein, Patrick A.; in't Veld, Pieter J.; Stevens, Mark Jackson

    2006-11-01

    The purpose of this project is to develop tools to model and simulate the processes of self-assembly and growth in biological systems from the molecular to the continuum length scales. The model biological system chosen for the study is the tendon fiber which is composed mainly of Type I collagen fibrils. The macroscopic processes of self-assembly and growth at the fiber scale arise from microscopic processes at the fibrillar and molecular length scales. At these nano-scopic length scales, we employed molecular modeling and simulation method to characterize the mechanical behavior and stability of the collagen triple helix and the collagen fibril. To obtain the physical parameters governing mass transport in the tendon fiber we performed direct numerical simulations of fluid flow and solute transport through an idealized fibrillar microstructure. At the continuum scale, we developed a mixture theory approach for modeling the coupled processes of mechanical deformation, transport, and species inter-conversion involved in growth. In the mixture theory approach, the microstructure of the tissue is represented by the species concentration and transport and material parameters, obtained from fibril and molecular scale calculations, while the mechanical deformation, transport, and growth processes are governed by balance laws and constitutive relations developed within a thermodynamically consistent framework.

  15. 42 CFR 433.112 - FFP for design, development, installation or enhancement of mechanized claims processing and...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... enhancement of mechanized claims processing and information retrieval systems. 433.112 Section 433.112 Public... processing and information retrieval systems. (a) Subject to paragraph (c) of this section, FFP is available... enhancement of a mechanized claims processing and information retrieval system only if the APD is approved...

  16. Petrochemical industry standards activity aimed at improving the mechanical integrity of process piping

    SciTech Connect

    Reynolds, J.T.

    1996-07-01

    This paper will cover numerous changes being made to existing standards and several new standards being created, all focusing on increasing mechanical integrity of petrochemical industry process piping. Those new standards include ones for (1) Risk-Based Inspection (2) Fitness for Service Analysis, (3) Positive Material Identification, and (4) In-service Inspection and Maintenance for Process Piping. A progress report is included for the Process Industry Practices (PIP) being created to consolidate individual company piping standards into one consistent industry set. And finally, recent initiatives toward standards cooperation/coordination between the American Petroleum Institute(API), American Society of Mechanical Engineers (ASME), International Standards Organization (ISO) and National Board are highlighted.

  17. The Effect of Process Parameters on the Microstructure and Mechanical Properties of Semisolid Cast Al6061

    NASA Astrophysics Data System (ADS)

    Hajihashemi, Mahdi; Niroumand, Behzad; Shamanian, Morteza

    2015-04-01

    An examination of the microstructure and mechanical properties of aluminum 6061 alloy samples produced by a miniature cooling slope is presented. The effects of several process parameters including pouring rate, cooling slope angle, superheat and cooling slope length on the microstructure and mechanical characteristics of the samples were investigated. An attempt was made to use the two-level factorial design method to determine the relationships between the process parameters and the properties of the semisolid aluminum 6061 alloy manufactured by the miniature cooling slope. Finally, an optimum processing region was identified. The interaction between the cooling slope length and the pouring rate ( BC); the interaction among the superheat, the pouring rate, and the cooling slope length ( ABC); and the cooling slope length (C), in the order mentioned, were identified as the most important effects.

  18. Microstructure and mechanical properties of ARB processed Mg-3% Gd alloy

    NASA Astrophysics Data System (ADS)

    Wu, J. Q.; Huang, S.; Wang, Y. H.; Wu, G. L.; Hansen, N.; Huang, X.

    2015-08-01

    Mg alloys have various advantages. However, the low formability due to the poor ductility of Mg alloys limits their engineering applications. In this study, an Mg-3% Gd alloys was chosen to explore processing approaches for improving its strength and ductility combination. The alloy was processed by accumulative roll-bonding (ARB) at 400 °C to 4 cycles followed by annealing at various temperatures. The microstructures after annealing were characterized by the electron backscatter diffraction technique and the mechanical properties were measured by a tensile test. It was found that the alloy has a good combination of strength and ductility after 2 cycle ARB processing followed by annealing at 290°C for 1h. The strength is 2.3 times higher than that of the fully annealed coarse grained alloy, and the elongation is comparable with that of fully annealed coarse grained counterpart. The good mechanical properties were related to the fine-sized heterogeneous microstructures and weakened texture.

  19. 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.

  20. 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.

  1. 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.

  2. Advanced numerical models for the thermo-mechanical-metallurgical analysis in hot forging processes

    NASA Astrophysics Data System (ADS)

    Ducato, Antonino; Fratini, Livan; Micari, Fabrizio

    2013-05-01

    In the paper a literature review of the numerical modeling of thermo-mechanical-metallurgical evolutions of a metal in hot forging operations is presented. In particular models of multiaxial loading tests are considered for carbon steels. The collected examples from literature regard phases transformations, also martensitic transformations, morphologies evolutions and transformation plasticity phenomena. The purpose of the tests is to show the correlation between the mechanical and the metallurgical behavior of a carbon steel during a combination of several types of loads. In particular a few mechanical tests with heat treatment are analyzed. Furthermore, Ti-6Al-4V titanium alloy is considered. Such material is a multi-phasic alloy, at room temperature made of two main different phases, namely Alpha and Beta, which evolve during both cooling and heating stages. Several numerical applications, conducted using a commercial implicit lagrangian FEM code are presented too. This code can conduct tri-coupled thermo-mechanical-metallurgical simulations of forming processes. The numerical model has been used to carry out a 3D simulation of a forging process of a complex shape part. The model is able to take into account the effects of all the phenomena resulting from the coupling of thermal, mechanical and metallurgical events. As simulation results strongly depend on the accuracy of input data, physical simulation experiments on real-material samples are carried out to characterize material behavior during phase transformation.

  3. 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.

  4. Processing Conditions Affecting Grain Size and Mechanical Properties in Nanocomposites Produced via Cold Spray

    NASA Astrophysics Data System (ADS)

    Cavaliere, P.; Perrone, A.; Silvello, A.

    2014-10-01

    Cold spray is a coating technology based on aerodynamics and high-speed impact dynamics. In this process, spray particles (usually 1-50 ?m in diameter) are accelerated to a high velocity (typically 300-1200 m/s) by a high-speed gas (pre-heated air, nitrogen, or helium) flow that is generated through a convergent-divergent de Laval-type nozzle. A coating is formed through the intensive plastic deformation of particles impacting on a substrate at a temperature below the melting point of the spray material. In the present paper the main processing parameters affecting the microstructural and mechanical behavior of metal-metal cold spray deposits are described. The effect of process parameters on grain refinement and mechanical properties were analyzed for composite particles of Al-Al2O3, Ni-BN, Cu-Al2O3, and Co-SiC. The properties of the formed nanocomposites were compared with those of the parent materials sprayed under the same conditions. The process conditions, leading to a strong grain refinement with an acceptable level of the deposit mechanical properties such as porosity and adhesion strength, are discussed.

  5. Spike-coding mechanisms of cerebellar temporal processing in classical conditioning and voluntary movements.

    PubMed

    Yamaguchi, Kenji; Sakurai, Yoshio

    2014-10-01

    Time is a fundamental and critical factor in daily life. Millisecond timing, which is the underlying temporal processing for speaking, dancing, and other activities, is reported to rely on the cerebellum. In this review, we discuss the cerebellar spike-coding mechanisms for temporal processing. Although the contribution of the cerebellum to both classical conditioning and voluntary movements is well known, the difference of the mechanisms for temporal processing between classical conditioning and voluntary movements is not clear. Therefore, we review the evidence of cerebellar temporal processing in studies of classical conditioning and voluntary movements and report the similarities and differences between them. From some studies, which used tasks that can change some of the temporal properties (e.g., the duration of interstimulus intervals) with keeping identical movements, we concluded that classical conditioning and voluntary movements may share a common spike-coding mechanism because simple spikes in Purkinje cells decrease at predicted times for responses regardless of the intervals between responses or stimulation. PMID:24985239

  6. Implementation of Statistical Process Control: Evaluating the Mechanical Performance of a Candidate Silicone Elastomer Docking Seal

    NASA Technical Reports Server (NTRS)

    Oravec, Heather Ann; Daniels, Christopher C.

    2014-01-01

    The National Aeronautics and Space Administration has been developing a novel docking system to meet the requirements of future exploration missions to low-Earth orbit and beyond. A dynamic gas pressure seal is located at the main interface between the active and passive mating components of the new docking system. This seal is designed to operate in the harsh space environment, but is also to perform within strict loading requirements while maintaining an acceptable level of leak rate. In this study, a candidate silicone elastomer seal was designed, and multiple subscale test articles were manufactured for evaluation purposes. The force required to fully compress each test article at room temperature was quantified and found to be below the maximum allowable load for the docking system. However, a significant amount of scatter was observed in the test results. Due to the stochastic nature of the mechanical performance of this candidate docking seal, a statistical process control technique was implemented to isolate unusual compression behavior from typical mechanical performance. The results of this statistical analysis indicated a lack of process control, suggesting a variation in the manufacturing phase of the process. Further investigation revealed that changes in the manufacturing molding process had occurred which may have influenced the mechanical performance of the seal. This knowledge improves the chance of this and future space seals to satisfy or exceed design specifications.

  7. A new perspective on the functioning of the brain and the mechanisms behind conscious processes

    PubMed Central

    Keppler, Joachim

    2013-01-01

    An essential prerequisite for the development of a theory of consciousness is the clarification of the fundamental mechanisms underlying conscious processes. In this article I present an approach that sheds new light on these mechanisms. This approach builds on stochastic electrodynamics (SED), a promising theoretical framework that provides a deeper understanding of quantum systems and reveals the origin of quantum phenomena. I outline the most important concepts and findings of SED and interpret the neurophysiological body of evidence in the context of these findings, indicating that the functioning of the brain rests upon exactly the same principles that are characteristic for quantum systems. On this basis, I construct a new hypothesis on the mechanisms behind conscious processes and discuss the new perspectives this hypothesis opens up for consciousness research. In particular, it offers the possibility of elucidating the relationship between brain and consciousness, of specifying the connection between consciousness and information, and of answering the question of what distinguishes conscious processes from unconscious processes. PMID:23641229

  8. In situ observation of penetration process in silica aerogel: Deceleration mechanism of hard spherical projectiles

    NASA Astrophysics Data System (ADS)

    Niimi, Rei; Kadono, Toshihiko; Arakawa, Masahiko; Yasui, Minami; Dohi, Koji; Nakamura, Akiko M.; Iida, Yosuke; Tsuchiyama, Akira

    2011-02-01

    A large number of cometary dust particles were captured with low-density silica aerogels by NASA's Stardust Mission. Knowledge of the details of the capture mechanism of hypervelocity particles in silica aerogel is needed in order to correctly derive the original particle features from impact tracks. However, the mechanism has not been fully understood yet. We shot hard spherical projectiles of several different materials into silica aerogel of density 60 mg cm -3 and observed their penetration processes using an image converter or a high-speed video camera. In order to observe the deceleration of projectiles clearly, we carried out impact experiments at two velocity ranges; ˜4 km s -1 and ˜200 m s -1. From the movies we took, it was indicated that the projectiles were decelerated by hydrodynamic force which was proportional to v2 ( v: projectile velocity) during the faster penetration process (˜4 km s -1) and they were merely overcoming the aerogel crushing strength during the slower penetration process (˜200 m s -1). We applied these deceleration mechanisms for whole capture process to calculate the track length. Our model well explains the track length in the experimental data set by Burchell et al. (Burchell, M.J., Creighton, J.A., Cole, M.J., Mann, J., Kearsley, A.T. [2001]. Meteorit. Planet. Sci. 36, 209-221).

  9. Laser trapping chemistry: from polymer assembly to amino acid crystallization.

    PubMed

    Sugiyama, Teruki; Yuyama, Ken-ichi; Masuhara, Hiroshi

    2012-11-20

    Laser trapping has served as a useful tool in physics and biology, but, before our work, chemists had not paid much attention to this technique because molecules are too small to be trapped in solution at room temperature. In late 1980s, we demonstrated laser trapping of micrometer-sized particles, developed various methodologies for their manipulation, ablation, and patterning in solution, and elucidated their dynamics and mechanism. In the 1990s, we started laser trapping studies on polymers, micelles, dendrimers, and gold, as well as polymer nanoparticles. Many groups also reported laser trapping studies of nanoclusters, DNA, colloidal suspensions, etc. Following these research streams, we have explored new molecular phenomena induced by laser trapping. Gradient force leading to trapping, mass transfer by local heating, and molecular reorientation following laser polarization are intimately coupled with molecular cluster and aggregate formation due to their intermolecular interactions, which depend on whether the trapping position is at the interface/surface or in solution. In this Account, we summarize our systematic studies on laser trapping chemistry and present some new advances and our future perspectives. We describe the laser trapping of nanoparticles, polymers, and amino acid clusters in solution by focusing a continuous wave 1064 nm laser beam on the molecules of interest and consider their dynamics and mechanism. In dilute solution, nanoparticles with weak mutual interactions are individually trapped at the focal point, while laser trapping of nanoparticles in concentrated solution assembles and confines numerous particles at the focal spot. The assembly of polymers during their laser trapping extends out from the focal point because of the interpolymer interactions, heat transfer, and solvent flow. When the trapping laser is focused at an interface between a thin heavy water solution film of glycine and a glass substrate, the assembled molecules nucleate and evolve to a liquid-liquid phase separation, or they will crystallize if the trapping laser is focused on the solution surface. Laser trapping can induce spatiotemporally the liquid and solid nucleation of glycine, and the dense liquid droplet or crystal formed can grow to a bulk scale. We can control the polymorph of the formed glycine crystal selectively by tuning trapping laser polarization and power. These results provide a new approach to elucidate dynamics and mechanism of crystallization and are the fundamental basis for studying not only enantioselective crystallization but also confined polymerization, trapping dynamics by ultrashort laser pulses, and resonance effect in laser trapping. PMID:23094993

  10. Focused plasmonic trapping of metallic particles.

    PubMed

    Min, Changjun; Shen, Zhe; Shen, Junfeng; Zhang, Yuquan; Fang, Hui; Yuan, Guanghui; Du, Luping; Zhu, Siwei; Lei, Ting; Yuan, Xiaocong

    2013-01-01

    Scattering forces in focused light beams push away metallic particles. Thus, trapping metallic particles with conventional optical tweezers, especially those of Mie particle size, is difficult. Here we investigate a mechanism by which metallic particles are attracted and trapped by plasmonic tweezers when surface plasmons are excited and focused by a radially polarized beam in a high-numerical-aperture microscopic configuration. This contrasts the repulsion exerted in optical tweezers with the same configuration. We believe that different types of forces exerted on particles are responsible for this contrary trapping behaviour. Further, trapping with plasmonic tweezers is found not to be due to a gradient force balancing an opposing scattering force but results from the sum of both gradient and scattering forces acting in the same direction established by the strong coupling between the metallic particle and the highly focused plasmonic field. Theoretical analysis and simulations yield good agreement with experimental results. PMID:24305554

  11. Unraveling the optomechanical nature of plasmonic trapping

    E-print Network

    Mestres, Pau; Quidant, Romain

    2015-01-01

    Non-invasive and ultra accurate optical manipulation of nanometer objects has recently gained a growing interest as a powerful enabling tool in nanotechnology and biophysics. In this context, Self-Induced Back-Action (SIBA) trapping in nano-optical cavities has shown a unique potential for trapping and manipulating nanometer-sized objects under low optical intensities. Yet, the existence of the SIBA effect has that far only been evidenced indirectly through its enhanced trapping performances. By enhancing the optomechanical interaction between the nano-cavity and the trapped object, we show for the first time direct evidence of the self-reconfiguration of the optical potential. Our observations enable us gaining further understanding of the SIBA mechanism and determine the optimum conditions to boost the performances of SIBA-based nano-optical tweezers.

  12. 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.

  13. Time dependence of switching oxide traps

    SciTech Connect

    Lelis, A.J.; Oldham, T.R. )

    1994-12-01

    Metal-oxide semiconductor field-effect transistors (MOSFETs) were irradiated and then annealed under alternating positive and negative bias. The magnitude of the reversible trapped-oxide charge component decayed over the course of several cycles (of 3 [times] 10[sup 3] s each) in one of two processes studied. The HDL hole trap model is shown to explain these and other recent results.

  14. Attention as a Process of Selection, Perception as a Process of Representation, and Phenomenal Experience as the Resulting Process of Perception Being Modulated by a Dedicated Consciousness Mechanism

    PubMed Central

    Bachmann, Talis

    2011-01-01

    Equivalence of attention and consciousness is disputed and necessity of attentional effects for conscious experience has become questioned. However, the conceptual landscape and interpretations of empirical evidence as related to this issue have remained controversial. Here I present some conceptual distinctions and research strategies potentially useful for moving forward when tackling this issue. Specifically, it is argued that we should carefully differentiate between pre-conscious processes and the processes resulting in phenomenal experience, move the emphasis from studying the effects of attention on the modality-specific and feature-specific perception to studying attentional effects on panmodal universal attributes of whatever conscious experience may be the case, and acknowledge that there is a specialized mechanism for leading to conscious experience of the pre-consciously represented contents autonomous from the mechanisms of perception, attention, memory, and cognitive control. PMID:22232612

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

    SciTech Connect

    Kolarik, Robert V.

    2005-11-11

    The Alloy Steel Business of The Timken Company won an award for the controlled thermo-mechanical processing (CTMP) project and assembled a strong international public/private partnership to execute the project. The premise of the CTMP work was to combine Timken's product understanding with its process expertise and knowledge of metallurgical and deformation fundamentals developed during the project to build a predictive process design capability. The CTMP effort succeeded in delivering a pc-based capability in the tube optimization model, with a virtual pilot plant (VPP) feature to represent the desired tube making process to predict the resultant microstructure tailored for the desired application. Additional tasks included a system for direct, online measurement of grain size and demonstration of application of CTMP via robotically enhanced manufacturing.

  16. Keep Your Eyes on Development: The Behavioral and Neurophysiological Development of Visual Mechanisms Underlying Form Processing

    PubMed Central

    van den Boomen, C.; van der Smagt, M. J.; Kemner, C.

    2012-01-01

    Visual form perception is essential for correct interpretation of, and interaction with, our environment. Form perception depends on visual acuity and processing of specific form characteristics, such as luminance contrast, spatial frequency, color, orientation, depth, and even motion information. As other cognitive processes, form perception matures with age. This paper aims at providing a concise overview of our current understanding of the typical development, from birth to adulthood, of form-characteristic processing, as measured both behaviorally and neurophysiologically. Two main conclusions can be drawn. First, the current literature conveys that for most reviewed characteristics a developmental pattern is apparent. These trajectories are discussed in relation to the organization of the visual system. The second conclusion is that significant gaps in the literature exist for several age-ranges. To complete our understanding of the typical and, by consequence, atypical development of visual mechanisms underlying form processing, future research should uncover these missing segments. PMID:22416236

  17. Panel report on coupled thermo-mechanical-hydro-chemical processes associated with a nuclear waste repository

    SciTech Connect

    Tsang, C.F.; Mangold, D.C.

    1984-07-01

    Four basic physical processes, thermal, hydrological, mechanical and chemical, are likely to occur in 11 different types of coupling during the service life of an underground nuclear waste repository. A great number of coupled processes with various degrees of importance for geological repositories were identified and arranged into these 11 types. A qualitative description of these processes and a tentative evaluation of their significance and the degree of uncertainty in prediction is given. Suggestions for methods of investigation generally include, besides theoretical work, laboratory and large scale field testing. Great efforts of a multidisciplinary nature are needed to elucidate details of several coupled processes under different temperature conditions in different geological formations. It was suggested that by limiting the maximum temperature to 100{sup 0}C in the backfill and in the host rock during the whole service life of the repository the uncertainties in prediction of long-term repository behavior might be considerably reduced.

  18. Realizing micro-opto-electro-mechanical devices through a commercial surface-micromachining process

    NASA Astrophysics Data System (ADS)

    Bright, Victor M.; Comtois, John H.; Sene, Darren E.; Reid, J. Robert; Gustafson, Steven C.; Watson, Edward A.

    1996-03-01

    The growing availability of commercial foundry processes allows easy implementation of micro-opto-electro-mechanical systems (MOEMS) for a variety of applications. Such applications go beyond single devices to include whole optical systems on a chip, comprising mirrors, gratings, Fresnel lenses, shutters, and actuators. Hinged and rotating structures, combined with powerful and compact thermal actuators, provide the means for positioning and operating these components. This paper presents examples of such systems built in a commercial polycrystalline silicon surface-micromachining process, the ARPA-sponsored multi-user MEMS process. Examples range from optical subcomponents to large mirror arrays and micro-interferometers. Also presented are linear arrays for combining the output of laser diode sources and for holographic data storage systems. Using the examples discussed in this paper, a designer can take advantage of commercially available surface-micromachining processes to design and develop MOEMS without the need for extensive in-house micromachining capabilities.

  19. Biosorption of malachite green by eggshells: mechanism identification and process optimization.

    PubMed

    Podstawczyk, Daria; Witek-Krowiak, Anna; Chojnacka, Katarzyna; Sadowski, Zygmunt

    2014-05-01

    In the present work, eggshells were used to remove a dye (malachite green) from wastewater. The study was focused on identification and describing the binding mechanism of the dye by eggshells in a biosorption process optimized by Response Surface Methodology based on the Box-Behnken Design. The mechanism of biosorption was determined by characterization of the biosorbent before and after biosorption using scanning electron microscopy, X-ray diffraction analysis, the Brunauer-Emmett-Teller isotherm method, Fourier transform infrared spectroscopy. The second-order polynomial equation and 3D response surface plots were used to quantitatively determine the relationships between dependent and independent variables. The obtained results suggested the mechanism of wastewater treatment that included physical adsorption, alkaline fading phenomenon and microprecipitation. The results of the present study showed that waste eggshells have the potential to be used as an inexpensive but effective biosorbent useful in wastewater treatment. PMID:24507580

  20. Structural and magnetic properties of nanocrystalline Fe-Co-Ni alloy processed by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Raanaei, Hossein; Eskandari, Hossein; Mohammad-Hosseini, Vahid

    2016-01-01

    In this present work, a nanostructured iron-cobalt-nickel alloy with Fe50Co30Ni20 composition has been processed by mechanical alloying. The structural and magnetic properties have been investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometer. It is shown that the crystallize size reaches to about 18.7 nm after 32 h milling time. A remarkable decrease in coercivity after 16 h milling time and also a continuous increase in remanent magnetization during the mechanical alloying process are observed. Heat treatment of the samples milled at 32 and 48 h demonstrates the crystalline constituent elements and also Fe3O4 crystalline phase.

  1. Diverse mechanisms for spliceosome-mediated 3? end processing of telomerase RNA

    PubMed Central

    Kannan, Ram; Helston, Rachel M.; Dannebaum, Richard O.; Baumann, Peter

    2015-01-01

    The 3? end of Schizosaccharomyces pombe telomerase RNA (SpTER1) is generated by spliceosomal cleavage, a reaction that corresponds to the first step of splicing. The observation that the spliceosome functions in 3? end processing raised questions about the evolutionary origin and conservation of this mechanism. We now present data in support of spliceosomes generating 3? ends of telomerase RNAs in other fungi. Strikingly, the mechanistic basis for restricting spliceosomal splicing to the first transesterification reaction differs substantially among species. Unlike S. pombe, two other fission yeasts rely on hyperstabilization of the U6 snRNA—5? splice site interaction to impede the 2nd step of splicing. In contrast, a non-canonical 5? splice site blocks the second transesterification reaction in Aspergillus species. These results demonstrate a conserved role for spliceosomes functioning in 3? end processing. Divergent mechanisms of uncoupling the two steps of splicing argue for multiple origins of this pathway. PMID:25598145

  2. Thermo-hydro-mechanical processes in fractured rock formations during a glacial advance

    NASA Astrophysics Data System (ADS)

    Selvadurai, A. P. S.; Suvorov, A. P.; Selvadurai, P. A.

    2015-07-01

    The paper examines the coupled thermo-hydro-mechanical (THM) processes that develop in a fractured rock region within a fluid-saturated rock mass due to loads imposed by an advancing glacier. This scenario needs to be examined in order to assess the suitability of potential sites for the location of deep geologic repositories for the storage of high-level nuclear waste. The THM processes are examined using a computational multiphysics approach that takes into account thermo-poroelasticity of the intact geological formation and the presence of a system of sessile but hydraulically interacting fractures (fracture zones). The modelling considers coupled thermo-hydro-mechanical effects in both the intact rock and the fracture zones due to contact normal stresses and fluid pressure at the base of the advancing glacier. Computational modelling provides an assessment of the role of fractures in modifying the pore pressure generation within the entire rock mass.

  3. Study on formation mechanism of periodic ripple on finished KDP crystal in cutting process

    NASA Astrophysics Data System (ADS)

    Tie, Guipeng; Guan, Chaoliang

    2015-07-01

    A kind of formation mechanism of periodic ripple on finished KDP (potassium dihydrogen phosphate) crystal in cutting process is studied by analyzing the change of equivalent axial stiffness of aerostatic spindle and consequent motion of spindle shaft caused by fluctuation of supply air pressure. The analysis shows that fluctuation of supply air pressure is one of the reasons to cause surface ripple. Correlative experiments are taken and validate the analysis. By strictly controlling air pressure fluctuation, the Peak-to-Valley (PV) value of surface ripple generated by both spiral turning and face flycutting processes are reduced to less than 5nm.

  4. Steam Trap Management 

    E-print Network

    Murphy, J. J.; Hirtner, H. H.

    1985-01-01

    A medium-sized plant of a high technology company is reaping the benefits of a Pro-active Steam Trap Program provided by Yarway's TECH/SERV Division. Initial work began March '84 and the most recent steam trap feasibility study conducted in March...

  5. Thermodynamic and fracture mechanical processes in the context of frost wedging in ice shelves

    NASA Astrophysics Data System (ADS)

    Plate, Carolin; Müller, Ralf; Humbert, Angelika; Gross, Dietmar

    2015-04-01

    Ice shelves, the link between ice shields or glaciers and the ocean are sensitive elements of the polar environment. The ongoing break up and disintegration of huge ice shelf parts or entire ice shelf demands for an explication of the underlying processes. The first analyses of crack growth and break up events in ice shelves date back to more than half a century. Nevertheless, the mechanisms that trigger and influence the collapse of whole ice shelf parts are not yet fully understood. Popular presumptions link ice shelf disintegration to surface meltwater and hydro fracturing, explaining break up events in warm polar seasons. Fracture events during colder seasons are possibly triggered by more complex mechanisms. A well-documented break up event at the Wilkins Ice Shelf bridge inspires the possibility of frost wedging as disintegration cause. The present study shows a two-dimensional thermo-dynamical model simulating the growth of an ice lid in a water-filled crevasse for measured surface temperatures. The influence of the crevasse geometry and the ice shelf temperature are shown. The resulting lid thickness is then used for the linear elastic fracture mechanical analysis. The maximum crack depth is estimated by comparing the computed stress intensity factors to critical values KIc obtained from literature. The thermodynamic as well as the fracture mechanical simulation are performed using the commercial finite element code COMSOL. The computation of KI follows in post processing routines in MATLAB exploiting the benefits of the concept of configurational forces.

  6. Investigation of Tc Migration Mechanism During Bulk Vitrification Process Using Re Surrogate

    SciTech Connect

    Kim, Dong-Sang; Bagaasen, Larry M.; Crum, Jarrod V.; Fluegel, Alex; Gallegos, Autumn B.; Martinez, Baudelio; Matyas, Josef; Meyer, Perry A.; Paulsen, Dan; Riley, Brian J.; Schweiger, Michael J.; Stewart, Charles W.; Swoboda, Robert G.; Yeager, John D.

    2006-12-04

    As a part of Bulk vitrification (BV) performance enhancement tasks, Laboratory scoping tests were performed in FY 2004-2005 to explore possible ways to reduce the amount of soluble Tc in the BV waste package. Theses scoping tests helped identify which mechanisms play an important role in the migration of Tc in the BV process (Hrma et al. 2005 and Kim et al. 2005). Based on the results from these scoping tests, additional tests were identified that will improve the understanding of Tc migration and to clearly identify the dominant mechanisms. The additional activities identified from previous studies were evaluated and prioritized for planning for Tasks 29 and 30 conducted in FY2006. Task 29 focused on the improved understanding of Tc migration mechanisms, and Task 30 focused on identifying the potential process changes that might reduce Tc/Re migration into the castable refractory block (CRB). This report summarizes the results from the laboratory- and crucible-scale tests in the lab for improved Tc migration mechanism understanding utilizing Re as a surrogate performed in Task 29.

  7. 3D Modeling of Coupled Rock Deformation and Thermo-Poro-Mechanical Processes in Fractures 

    E-print Network

    Rawal, Chakra

    2012-07-16

    for the degree of DOCTOR OF PHILOSOPHY Approved by: Chair of Committee, Ahmad Ghassemi Committee Members, Stephen A. Holditch Peter P. Valk? Theofanis Strouboulis Head of Department, A. Daniel Hill May 2012 Major Subject: Petroleum... Engineering iii ABSTRACT 3D Modeling of Coupled Rock Deformation and Thermo-Poro-Mechanical Processes in Fractures. (May 2012) Chakra Rawal, B.E.; M.Sc., Tribhuvan University Chair of Advisory Committee: Dr. Ahmad Ghassemi Problems...

  8. Recent advances in endpoint and in-line monitoring techniques for chemical-mechanical polishing processes

    NASA Astrophysics Data System (ADS)

    Stein, David J.; Hetherington, Dale L.

    2001-04-01

    We present a summary of the recent advances in endpoint and in-line monitoring techniques for chemical-mechanical polishing (CMP) processes. We discuss the technical challenges and review some of the approaches that have been published and/or patented. These methods include optical, thermal (pad temperature), friction (torque motor current), electrochemical, chemical, electrical, and acoustic (vibration). We also present experimental data obtained in our laboratory using selected endpoint methods for metal and oxide CMP.

  9. Process for improving mechanical properties of epoxy resins by addition of cobalt ions

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St.clair, A. K. (inventors)

    1984-01-01

    A resin product useful as an adhesive, composite or casting resin is described as well as the process used in its preparation to improve its flexural strength mechanical property characteristics. Improved flexural strength is attained with little or no change in density, thermal stability or moisture resistance by chemically incorporating 1.2% to 10.6% by weight Co(3) ions in an epoxidized resin system.

  10. Kinetics and mechanism of the oxidation process of two-component Fe-Al alloys

    NASA Technical Reports Server (NTRS)

    Przewlocka, H.; Siedlecka, J.

    1982-01-01

    The oxidation process of two-component Fe-Al alloys containing up to 7.2% Al and from 18 to 30% Al was studied. Kinetic measurements were conducted using the isothermal gravimetric method in the range of 1073-1223 K and 1073-1373 K for 50 hours. The methods used in studies of the mechanism of oxidation included: X-ray microanalysis, X-ray structural analysis, metallographic analysis and marker tests.

  11. Medicaid Program; Mechanized Claims Processing and Information Retrieval Systems (90/10). Final rule.

    PubMed

    2015-12-01

    This final rule will extend enhanced funding for Medicaid eligibility systems as part of a state's mechanized claims processing system, and will update conditions and standards for such systems, including adding to and updating current Medicaid Management Information Systems (MMIS) conditions and standards. These changes will allow states to improve customer service and support the dynamic nature of Medicaid eligibility, enrollment, and delivery systems. PMID:26638224

  12. Multiscale Simulation of Thermo-mechanical Processes in Irradiated Fission-reactor Materials

    SciTech Connect

    El-Azab, Anter

    2012-05-28

    This report contains a summary of progress made on the subtask area on phase field model development for microstructure evolution in irradiated materials, which was a part of the Computational Materials Science Network (CMSN) project entitled: Multiscale Simulation of Thermo-mechanical Processes in Irradiated Fission-reactor Materials. The model problem chosen has been that of void nucleation and growth under irradiation conditions in single component systems.

  13. 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

  14. Antihydrogen trapping assisted by sympathetically cooled positrons

    NASA Astrophysics Data System (ADS)

    Madsen, N.; Robicheaux, F.; Jonsell, S.

    2014-06-01

    Antihydrogen, the bound state of an antiproton and a positron, is of interest for use in precision tests of nature's fundamental symmetries. Antihydrogen formed by carefully merging cold plasmas of positrons and antiprotons has recently been trapped in magnetic traps. The efficiency of trapping is strongly dependent on the temperature of the nascent antihydrogen, which, to be trapped, must have a kinetic energy less than the trap depth of \\sim 0.5\\;{{K}}\\;{{k}_{B}}. In the conditions in the ALPHA experiment, the antihydrogen temperature seems dominated by the temperature of the positron plasma used for the synthesis. Cold positrons are therefore of paramount interest in that experiment. In this paper, we propose an alternative route to make ultra-cold positrons for enhanced antihydrogen trapping. We investigate theoretically how to extend previously successful sympathetic cooling of positrons by laser-cooled positive ions to be used for antihydrogen trapping. Using simulations, we investigate the effectiveness of such cooling in conditions similar to those in ALPHA, and discuss how the formation process and the nascent antihydrogen may be influenced by the presence of positive ions. We argue that this technique is a viable alternative to methods such as evaporative and adiabatic cooling, and may overcome limitations faced by these. Ultra-cold positrons, once available, may also be of interest for a range of other applications.

  15. Subsurface damage mechanism of high speed grinding process in single crystal silicon revealed by atomistic simulations

    NASA Astrophysics Data System (ADS)

    Li, Jia; Fang, Qihong; Zhang, Liangchi; Liu, Youwen

    2015-01-01

    Three-dimensional molecular dynamics (MD) simulations are performed to investigate the nanoscale grinding process of single crystal silicon using diamond tool. The effect of grinding speed on subsurface damage and grinding surface integrity by analyzing the chip, dislocation movement, and phase transformation are studied. We also establish an analytical model to calculate several important stress fields including hydrostatic stress and von Mises stress for studying subsurface damage mechanism, and obtain the dislocation density on the grinding subsurface. The results show that a higher grinding velocity in machining brittle material silicon causes a larger chip and a higher temperature, and reduces subsurface damage. However, when grinding velocity is above 180 m s-1, subsurface damage thickness slightly increases because a higher grinding speed leads to the increase in grinding force and temperature, which accelerate dislocation nucleation and motion. Subsurface damage is studied by the evolution of surface area at first time for more obvious observation on transition from ductile to brittle, that provides valuable reference for machining nanometer devices. The von Mises stress and the hydrostatic stress play an important role in the grinding process, and explain the subsurface damage though dislocation mechanism under high stress status. The dislocation nucleation and motion induced plastic deformation during grinding process can better reveal subsurface damage mechanism considering to stress and temperature acting on the dislocations.

  16. Influence of pore morphology and topology on capillary trapping in geological carbon dioxide sequestration

    NASA Astrophysics Data System (ADS)

    Andersson, L.; Harper, E.; Herring, A. L.; Wildenschild, D.

    2012-12-01

    Current carbon capture and storage (CCS) techniques could reduce the release of anthropogenic CO2 into the atmosphere by subsurface sequestration of CO2 in saline aquifers. In geological storage CO2 is injected into deep underground porous formations where CO2 is in the supercritical state. Deep saline aquifers are particularly attractive because of their abundance and potentially large storage volumes. Despite very broad research efforts there are still substantial uncertainties related to the effectiveness of the trapping, dissolution, and precipitation processes controlling the permanent storage of CO2. After injection of CO2 the saline water (brine) will imbibe back and reoccupy the pore space as the CO2 moves upwards, trapping a large part of the CO2. This trapping mechanism is known as capillary trapping and occurs as isolated CO2 bubbles are locked in the brine inside the pores of the porous rock. The large-scale movement of CO2 within the brine is thereby prevented. This mechanism thus constitutes an important storage mechanism after the CO2 injection until the subsequent dissolution trapping and precipitation of carbonate mineral. The capillary trapping of CO2 depends largely on the shape and interconnectivity of the pore space and it is therefore important to study the influence of pore scale morphology and topology to understand and optimize large scale capillary trapping. We use a high pressure set-up, designed for supercritical CO2 conditions, with a flow cell compatible with synchrotron-based X-ray computed micro-tomography (CMT) to generate high-resolution images to study capillary trapping. We use sintered glass bead columns as an approximation for unconsolidated reservoir systems. The smooth surface glass bead data allow us to separate the chemistry and surface roughness effects of the porous medium from the effect of the morphology and topology on the capillary trapping. We will relate these aspects of the pore space to the distribution of the fluids (wetting and non-wetting) and initial and residual non-wetting phase saturations. Potential wettability alteration due to exposure of the beads to supercritical CO2 is also explored by comparing high-pressure and low-pressure experimental results.

  17. Receptor Response in Venus's Fly-Trap

    PubMed Central

    Jacobson, Stuart L.

    1965-01-01

    The insect-trapping movement of the plant Dionaea muscipula (Venus's fly-trap) is mediated by the stimulation of mechanosensory hairs located on the surface of the trap. It is known that stimulation of the hairs is followed by action potentials which are propagated over the surface of the trap. It has been reported that action potentials always precede trap closure. The occurrence of non-propagated receptor potentials is reported here. Receptor potentials always precede the action potentials. The receptor potential appears to couple the mechanical stimulation step to the action potential step of the preying sequence. Receptor potentials elicited by mechanical stimulation of a sensory hair were measured by using the hair as an integral part of the current-measuring path. The tip of the hair was cut off exposing the medullary tissue; this provided a natural extension of the measuring electrode into the receptor region at the base of the hair. A measuring pipette electrode was slipped over the cut tip of the hair. Positive and negative receptor potentials were measured. Evidence is presented which supports the hypothesis that the positive and negative receptor potentials originate from independent sources. An analysis is made of (a) the relation of the parameters of mechanical stimuli to the magnitude of the receptor potential, and (b) the relation of the receptor potentials to the action potential. The hypothesis that the positive receptor potential is the generator of the action potential is consistent with these data. PMID:5862498

  18. Using vacuum pyrolysis and mechanical processing for recycling waste printed circuit boards.

    PubMed

    Long, Laishou; Sun, Shuiyu; Zhong, Sheng; Dai, Wencan; Liu, Jingyong; Song, Weifeng

    2010-05-15

    The constant growth in generation of waste printed circuit boards (WPCB) poses a huge disposal problem because they consist of a heterogeneous mixture of organic and metallic chemicals as well as glass fiber. Also the presence of heavy metals, such as Pb and Cd turns this scrap into hazardous waste. Therefore, recycling of WPCB is an important subject not only from the recovery of valuable materials but also from the treatment of waste. The aim of this study was to present a recycling process without negative impact to the environment as an alternative for recycling WPCB. In this work, a process technology containing vacuum pyrolysis and mechanical processing was employed to recycle WPCB. At the first stage of this work, the WPCB was pyrolyzed under vacuum in a self-made batch pilot-scale fixed bed reactor to recycle organic resins contained in the WPCB. By vacuum pyrolysis the organic matter was decomposed to gases and liquids which could be used as fuels or chemical material resources, however, the inorganic WPCB matter was left unaltered as solid residues. At the second stage, the residues obtained at the first stage were investigated to separate and recover the copper through mechanical processing such as crushing, screening, and gravity separation. The copper grade of 99.50% with recovery of 99.86% based on the whole WPCB was obtained. And the glass fiber could be obtained by calcinations in a muffle furnace at 600 degrees C for 10 min. This study had demonstrated the feasibility of vacuum pyrolysis and mechanical processing for recycling WPCB. PMID:20060640

  19. Disentangling cognitive processes from neural activation and psychic mechanisms: the example of empathy.

    PubMed

    Guilé, Jean-Marc

    2010-12-01

    Empathy processes can be explored within a three-level model distinguishing neuronal, cognitive and intra-psychic operating levels. Cognitive and intra-psychic processes need not to be collapsed. Neural systems involved in empathy are described through neuroimaging and event-related potential (ERP) studies. On the cognitive level, empathy is threefold: procedural, semantic and biographical. Automatically activated since birth, procedural empathy processes are deeply enrooted in visuo-motor response capacities and responsible for automatic mimicry. These processes might rely on a prior sensori-motor contagion system. Semantic empathy parallels language development and expresses connexion between words, meaning and emotion. Biographical emerges later in life and corresponds to the interweaving of personal experience with feelings and words, together with a capacity to bridge with the others' experiences. On the intra-psychic level, defence mechanisms as well as identification processes, depicted from a subjective and interpersonal standpoint, are corresponding, without being similar, to empathetic processes described in cognitive neuroscience studies. Studies on semantic empathy need to control for the participants biographical information and concomitant memory activation. The interface between cognitive and intra-psychic processes needs to be further investigated. PMID:20888907

  20. Process modeling of fine-blanking using thermo-mechanical coupling method

    NASA Astrophysics Data System (ADS)

    Chen, Zhang-Hua

    The primary objectives of the research project are to investigate into the failure mechanism of fine-blanking process and to develop a methodology that can be used to predict failure in fine-blanking. The scope of this research work is to study the forming mechanism and failure characteristics occurring during fine-blanking based on theoretical modelling, numerical simulation, and experimental investigation. In the numerical aspect, a step-wise and staggered decoupling strategy was adopted to handle coupling between mechanical deformation and temperature variation. Based on this strategy, an updated Lagrangian thermo-mechanical finite element programme together with a special designed local remeshing procedure has been successfully developed to solve large deformation problems. Using the programme, the fine-blanking process has been simulated. In order to ensure the accuracy of simulation, the major process attributes such as vee-ring, ejector and the edge radii of the tools have been incorporated into the finite element model. From the numerical results, it has been realized that drastic variation of stress triaxiality during fine-blanking processes can cause material damage in the form of microcrack initiation, growth, and coalescence. By applying the concept of damage mechanics, the evolution of damage at different stages of fine-blanking has been estimated. The predicted value of damage energy density agrees with which has been published in related literature. In order to measure the strain distribution for validating the numerical findings, the effective strain has been measured experimentally on the meridian plane of fine-blanked specimens. By using the photochemical etching method, a chessboard pattern mesh has been pre-etched on the cross-section of the specimens. After fine-blanking, the coordinates of specific points on the meridian plane of the fine-blanked specimen were recorded digitally and thus the deformation gradient at the points could be estimated. Furthermore, the effective strain was calculated in terms of the deformation gradient tensor. To make clear the evolution of microstructure in the shear zone, examinations of metallurgical microstructure by means of optical microscopy and SEM have been carried out. It has been observed that the grains were highly rotated and elongated in the plastic zone, whilst in the other regions equiaxed fine-grained microstructures remained approximately unchanged. The presence of voids and micro-cracks proved that material damage developed at the final stage of fine-blanking. Moreover, the existence of local recrystallized microstructure may imply that the severe plastic strain and temperature rise could cause recrystallization in fine-blanking processes. (Abstract shortened by UMI.)

  1. Nano-photonic Light Trapping In Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Callahan, Dennis M., Jr.

    Over the last several decades there have been significant advances in the study and understanding of light behavior in nanoscale geometries. Entire fields such as those based on photonic crystals, plasmonics and metamaterials have been developed, accelerating the growth of knowledge related to nanoscale light manipulation. Coupled with recent interest in cheap, reliable renewable energy, a new field has blossomed, that of nanophotonic solar cells. In this thesis, we examine important properties of thin-film solar cells from a nanophotonics perspective. We identify key differences between nanophotonic devices and traditional, thick solar cells. We propose a new way of understanding and describing limits to light trapping and show that certain nanophotonic solar cell designs can have light trapping limits above the so called ray-optic or ergodic limit. We propose that a necessary requisite to exceed the traditional light trapping limit is that the active region of the solar cell must possess a local density of optical states (LDOS) higher than that of the corresponding, bulk material. Additionally, we show that in addition to having an increased density of states, the absorber must have an appropriate incoupling mechanism to transfer light from free space into the optical modes of the device. We outline a portfolio of new solar cell designs that have potential to exceed the traditional light trapping limit and numerically validate our predictions for select cases. We emphasize the importance of thinking about light trapping in terms of maximizing the optical modes of the device and efficiently coupling light into them from free space. To further explore these two concepts, we optimize patterns of superlattices of air holes in thin slabs of Si and show that by adding a roughened incoupling layer the total absorbed current can be increased synergistically. We suggest that the addition of a random scattering surface to a periodic patterning can increase incoupling by lifting the constraint of selective mode occupation associated with periodic systems. Lastly, through experiment and simulation, we investigate a potential high efficiency solar cell architecture that can be improved with the nanophotonic light trapping concepts described in this thesis. Optically thin GaAs solar cells are prepared by the epitaxial liftoff process by removal from their growth substrate and addition of a metallic back reflector. A process of depositing large area nano patterns on the surface of the cells is developed using nano imprint lithography and implemented on the thin GaAs cells.

  2. Steps towards High-Efficiency Trapping of Radioactive Isotopes in a Magneto-Optical Trap.*

    NASA Astrophysics Data System (ADS)

    Guckert, R.; Sandberg, V.; Tupa, D.; Vieira, D. J.

    1996-05-01

    As part of an effort to measure parity nonconserving atomic transition rates in a series of Cs radioisotopes(D. J. Vieira, C. E. Wieman et al., LAMPF Proposal 1303 (1992)), we are working on the efficient coupling of an magneto-optical trap (MOT) to a mass separator. We have established a test stand for optical trapping which is used for the off-line development of a high-efficiency MOT. Our trap features a dry-film coated(M. Stephens and C.E. Wieman, Phys. Rev. Let. 72), 24 (1994) cell with large (5 cm) windows to permit the use of large diameter, high power laser beams to increase the efficiency of the trapping process. Studies of the effect of detuning, magnetic field gradient, laser beam intensity and different beam sizes on the number of trapped atoms are presented. *This work is supported by the Department of Energy

  3. Deciphering the photochemical mechanisms describing the UV-induced processes occurring in solvated guanine monophosphate

    PubMed Central

    Altavilla, Salvatore F.; Segarra-Martí, Javier; Nenov, Artur; Conti, Irene; Rivalta, Ivan; Garavelli, Marco

    2015-01-01

    The photophysics and photochemistry of water-solvated guanine monophosphate (GMP) are here characterized by means of a multireference quantum-chemical/molecular mechanics theoretical approach (CASPT2//CASSCF/AMBER) in order to elucidate the main photo-processes occurring upon UV-light irradiation. The effect of the solvent and of the phosphate group on the energetics and structural features of this system are evaluated for the first time employing high-level ab initio methods and thoroughly compared to those in vacuo previously reported in the literature and to the experimental evidence to assess to which extent they influence the photoinduced mechanisms. Solvated electronic excitation energies of solvated GMP at the Franck-Condon (FC) region show a red shift for the ??* La and Lb states, whereas the energy of the oxygen lone-pair n?* state is blue-shifted. The main photoinduced decay route is promoted through a ring-puckering motion along the bright lowest-lying La state toward a conical intersection (CI) with the ground state, involving a very shallow stationary point along the minimum energy pathway in contrast to the barrierless profile found in gas-phase, the point being placed at the end of the minimum energy path (MEP) thus endorsing its ultrafast deactivation in accordance with time-resolved transient and photoelectron spectroscopy experiments. The role of the n?* state in the solvated system is severely diminished as the crossings with the initially populated La state and also with the Lb state are placed too high energetically to partake prominently in the deactivation photo-process. The proposed mechanism present in solvated and in vacuo DNA/RNA chromophores validates the intrinsic photostability mechanism through CI-mediated non-radiative processes accompanying the bright excited-state population toward the ground state and subsequent relaxation back to the FC region. PMID:25941671

  4. Deciphering the photochemical mechanisms describing the UV-induced processes occurring in solvated guanine monophosphate

    NASA Astrophysics Data System (ADS)

    Altavilla, Salvatore; Segarra-Martí, Javier; Nenov, Artur; Conti, Irene; Rivalta, Ivan; Garavelli, Marco

    2015-04-01

    The photophysics and photochemistry of water-solvated guanine monophosphate (GMP) are here characterized by means of a multireference quantum-chemical/molecular mechanics theoretical approach (CASPT2//CASSCF/AMBER) in order to elucidate the main photo-processes occurring upon UV-light irradiation. The effect of the solvent and of the phosphate group on the energetics and structural features of this system are evaluated for the first time employing high-level ab initio methods and thoroughly compared to those in vacuo previously reported in the literature and to the experimental evidence to assess to which extent they influence the photoinduced mechanisms. Solvated electronic excitation energies of solvated GMP at the Franck-Condon (FC) region show a red shift for the ??* La and Lb states, whereas the energy of the oxygen lone-pair n?* state is blue-shifted. The main photoinduced decay route is promoted through a ring-puckering motion along the bright lowest-lying La state towards a conical intersection (CI) with the ground state, involving a very shallow stationary point along the minimum energy pathway in contrast to the barrierless profile found in gas-phase, the point being placed at the end of the minimum energy path (MEP) thus endorsing its ultrafast deactivation in accordance with time-resolved transient and photoelectron spectroscopy experiments. The role of the n?* state in the solvated system is severely diminished as the crossings with the initially populated La state and also with the Lb state are placed too high energetically to partake prominently in the deactivation photo-process. The proposed mechanism present in solvated and in vacuo DNA/RNA chromophores validates the intrinsic photostability mechanism through CI-mediated non-radiative processes accompanying the bright excited-state population towards the ground state and subsequent relaxation back to the FC region.

  5. ECCENTRICITY TRAP: TRAPPING OF RESONANTLY INTERACTING PLANETS NEAR THE DISK INNER EDGE

    SciTech Connect

    Ogihara, Masahiro; Ida, Shigeru; Duncan, Martin J. E-mail: ida@geo.titech.ac.j

    2010-10-01

    Using orbital integration and analytical arguments, we have found a new mechanism (an 'eccentricity trap') to halt type I migration of planets near the inner edge of a protoplanetary disk. Because asymmetric eccentricity damping due to disk-planet interaction on the innermost planet at the disk edge plays a crucial role in the trap, this mechanism requires continuous eccentricity excitation and hence works for a resonantly interacting convoy of planets. This trap is so strong that the edge torque exerted on the innermost planet can completely halt type I migrations of many outer planets through mutual resonant perturbations. Consequently, the convoy stays outside the disk edge, as a whole. We have derived a semi-analytical formula for the condition for the eccentricity trap and predict how many planets are likely to be trapped. We found that several planets or more should be trapped by this mechanism in protoplanetary disks that have cavities. It can be responsible for the formation of non-resonant, multiple, close-in super-Earth systems extending beyond 0.1 AU. Such systems are being revealed by radial velocity observations to be quite common around solar-type stars.

  6. Investigation of trench and contact hole shrink mechanism in the negative tone develop process

    NASA Astrophysics Data System (ADS)

    Mehta, Sohan Singh; Higgins, Craig; Chauhan, Vikrant; Pal, Shyam; Koh, Hui Peng; Fakhoury, Jean Raymond; Gao, Shaowen; Subramany, Lokesh; Iqbal, Salman; Jeon, Bumhwan; Morrison, Pedro; Karanikas, Chris; Wei, Yayi; Cho, David R.

    2013-03-01

    The objective of this work was to study the trench and contact hole shrink mechanism in negative tone develop resist processes and its manufacturability challenges associated for 20nm technology nodes and beyond. Process delay from post-exposure to develop, or "queue time", is studied in detail. The impact of time link delay on resolved critical dimension (CD) is fully characterized for patterned resist and etched geometries as a function of various process changes. In this study, we assembled a detailed, theoretical model and performed experimental work to correlated time link delay to acid diffusion within the resist polymer matrix. Acid diffusion is determined using both a modulation transfer function for diffusion and simple approximation based on Fick's law of diffusion.

  7. Mechanical property changes in porous low-k dielectric thin films during processing

    SciTech Connect

    Stan, G. Gates, R. S.; Kavuri, P.; Torres, J.; Michalak, D.; Ege, C.; Bielefeld, J.; King, S. W.

    2014-10-13

    The design of future generations of Cu-low-k dielectric interconnects with reduced electronic crosstalk often requires engineering materials with an optimal trade off between their dielectric constant and elastic modulus. This is because the benefits associated with the reduction of the dielectric constant by increasing the porosity of materials, for example, can adversely affect their mechanical integrity during processing. By using load-dependent contact-resonance atomic force microscopy, the changes in the elastic modulus of low-k dielectric materials due to processing were accurately measured. These changes were linked to alterations sustained by the structure of low-k dielectric films during processing. A two-phase model was used for quantitative assessments of the elastic modulus changes undergone by the organosilicate skeleton of the structure of porous and pore-filled dielectrics.

  8. Dynamic mechanical properties of hydroxyapatite/polyethylene oxide nanocomposites: characterizing isotropic and post-processing microstructures

    NASA Astrophysics Data System (ADS)

    Shofner, Meisha; Lee, Ji Hoon

    2012-02-01

    Compatible component interfaces in polymer nanocomposites can be used to facilitate a dispersed morphology and improved physical properties as has been shown extensively in experimental results concerning amorphous matrix nanocomposites. In this research, a block copolymer compatibilized interface is employed in a semi-crystalline matrix to prevent large scale nanoparticle clustering and enable microstructure construction with post-processing drawing. The specific materials used are hydroxyapatite nanoparticles coated with a polyethylene oxide-b-polymethacrylic acid block copolymer and a polyethylene oxide matrix. Two particle shapes are used: spherical and needle-shaped. Characterization of the dynamic mechanical properties indicated that the two nanoparticle systems provided similar levels of reinforcement to the matrix. For the needle-shaped nanoparticles, the post-processing step increased matrix crystallinity and changed the thermomechanical reinforcement trends. These results will be used to further refine the post-processing parameters to achieve a nanocomposite microstructure with triangulated arrays of nanoparticles.

  9. Mechanical property of tubular composites manufactured from braided-pultrusion process

    SciTech Connect

    Byun, J.H.; Lee, S.K.

    1994-12-31

    In order to realize the potential of composite materials, it is imperative to develop a manufacturing process, to understand the microstructures, and to assess the structural performance of the composite. The braided-pultrusion process, which combines the pultrusion process with the braiding technology, has been developed by utilizing a novel resin impregnation device. The goal of the development is to achieve both cost-effectiveness and performance of the composite. The tubular composites of diameter 5.3 mm have been produced using Kevlar 49 fiber and polyester resin. In order to assess the mechanical performance of the composites, an analytical method for predicting the elastic constants has been developed. The analysis includes the geometric model of a unit cell, coordinate transformation, and averaging of stiffness and compliance constants of the constituent materials. The analytic predictions were compared favorably with experimental results.

  10. Charged nanodiamonds in a Paul trap

    NASA Astrophysics Data System (ADS)

    Streed, Erik

    2015-05-01

    Colloidal nanodiamonds were ionized with atmospheric electrospray and loaded into a Paul trap. Fluorescence from atom-like NV0 and NV- colour centres has been observed. The very low intrinsic absorption of bulk diamond is favourable for reducing the heating of cooled, trapped, nanodiamond ions from the surrounding blackbody radiation of the trapping apparatus. The isolated environment of the ion trap is also favourable for in-situ modification of nanodiamond to reduce absorption inducing defects through either physical or chemical processes. The presence or intentional introduction of high luminescence atom-like colour centre defects such as NV or SiV offer the prospect of direct laser cooling in nanodiamonds with low emissivity. Such laser cooled nano-ions are of interest for sympathetically cooling ions of similar charge/mass ratios that lack closed optical transitions, such as large biomolecules. ARC Future Fellow.

  11. Recovery of copper from printed circuit boards scraps by mechanical processing and electrometallurgy.

    PubMed

    Veit, Hugo Marcelo; Bernardes, Andréa Moura; Ferreira, Jane Zoppas; Tenório, Jorge Alberto Soares; de Fraga Malfatti, Célia

    2006-10-11

    The constant growth in generation of solid wastes stimulates studies of recycling processes. The electronic scrap is part of this universe of obsolete and/or defective materials that need to be disposed of more appropriately, or then recycled. In this work, printed circuit boards, that are part of electronic scrap and are found in almost all electro-electronic equipments, were studied. Printed circuit boards were collected in obsolete or defective personal computers that are the largest source of this kind of waste. Printed circuit boards are composed of different materials such as polymers, ceramics and metals, which makes the process more difficult. However, the presence of metals, such as copper and precious metals encourage recycling studies. Also the presence of heavy metals, as Pb and Cd turns this scrap into dangerous residues. This demonstrates the need to search for solutions of this kind of residue, in order to have it disposed in a proper way, without harming the environment. At the first stage of this work, mechanical processing was used, as comminution followed by size, magnetic and electrostatic separation. By this process it was possible to obtain a concentrated fraction in metals (mainly Cu, Pb and Sn) and another fraction containing polymers and ceramics. The copper content reached more than 50% in mass in most of the conductive fractions and significant content of Pb and Sn. At the second stage, the fraction concentrated in metals was dissolved with acids and treated in an electrochemical process in order to recover the metals separately, especially copper. The results demonstrate the technical viability of recovering copper using mechanical processing followed by an electrometallurgical technique. The copper content in solution decayed quickly in all the experiments and the copper obtained by electrowinning is above 98% in most of the tests. PMID:16757116

  12. A quantum mechanics-based framework for image processing and its application to image segmentation

    NASA Astrophysics Data System (ADS)

    Youssry, Akram; El-Rafei, Ahmed; Elramly, Salwa

    2015-10-01

    Quantum mechanics provides the physical laws governing microscopic systems. A novel and generic framework based on quantum mechanics for image processing is proposed in this paper. The basic idea is to map each image element to a quantum system. This enables the utilization of the quantum mechanics powerful theory in solving image processing problems. The initial states of the image elements are evolved to the final states, controlled by an external force derived from the image features. The final states can be designed to correspond to the class of the element providing solutions to image segmentation, object recognition, and image classification problems. In this work, the formulation of the framework for a single-object segmentation problem is developed. The proposed algorithm based on this framework consists of four major steps. The first step is designing and estimating the operator that controls the evolution process from image features. The states associated with the pixels of the image are initialized in the second step. In the third step, the system is evolved. Finally, a measurement is performed to determine the output. The presented algorithm is tested on noiseless and noisy synthetic images as well as natural images. The average of the obtained results is 98.5 % for sensitivity and 99.7 % for specificity. A comparison with other segmentation algorithms is performed showing the superior performance of the proposed method. The application of the introduced quantum-based framework to image segmentation demonstrates high efficiency in handling different types of images. Moreover, it can be extended to multi-object segmentation and utilized in other applications in the fields of signal and image processing.

  13. Disentangling mechanisms that mediate the balance between stochastic and deterministic processes in microbial succession

    PubMed Central

    Dini-Andreote, Francisco; Stegen, James C.; van Elsas, Jan Dirk; Salles, Joana Falcão

    2015-01-01

    Ecological succession and the balance between stochastic and deterministic processes are two major themes within microbial ecology, but these conceptual domains have mostly developed independent of each other. Here we provide a framework that integrates shifts in community assembly processes with microbial primary succession to better understand mechanisms governing the stochastic/deterministic balance. Synthesizing previous work, we devised a conceptual model that links ecosystem development to alternative hypotheses related to shifts in ecological assembly processes. Conceptual model hypotheses were tested by coupling spatiotemporal data on soil bacterial communities with environmental conditions in a salt marsh chronosequence spanning 105 years of succession. Analyses within successional stages showed community composition to be initially governed by stochasticity, but as succession proceeded, there was a progressive increase in deterministic selection correlated with increasing sodium concentration. Analyses of community turnover among successional stages—which provide a larger spatiotemporal scale relative to within stage analyses—revealed that changes in the concentration of soil organic matter were the main predictor of the type and relative influence of determinism. Taken together, these results suggest scale-dependency in the mechanisms underlying selection. To better understand mechanisms governing these patterns, we developed an ecological simulation model that revealed how changes in selective environments cause shifts in the stochastic/deterministic balance. Finally, we propose an extended—and experimentally testable—conceptual model integrating ecological assembly processes with primary and secondary succession. This framework provides a priori hypotheses for future experiments, thereby facilitating a systematic approach to understand assembly and succession in microbial communities across ecosystems. PMID:25733885

  14. The consequence of biologic graft processing on blood interface biocompatibility and mechanics.

    PubMed

    Van de Walle, Aurore B; Uzarski, Joseph S; McFetridge, Peter S

    2015-09-01

    Processing ex vivo derived tissues to reduce immunogenicity is an effective approach to create biologically complex materials for vascular reconstruction. Due to the sensitivity of small diameter vascular grafts to occlusive events, the effect of graft processing on critical parameters for graft patency, such as peripheral cell adhesion and wall mechanics, requires detailed analysis. Isolated human umbilical vein sections were used as model allogenic vascular scaffolds that were processed with either: 1. sodium dodecyl sulfate (SDS), 2. ethanol/acetone (EtAc), or 3. glutaraldehyde (Glu). Changes in material mechanics were assessed via uniaxial tensile testing. Peripheral cell adhesion to the opaque grafting material was evaluated using an innovative flow chamber that allows direct observation of the blood-graft interface under physiological shear conditions. All treatments modified the grafts tensile strain and stiffness properties, with physiological modulus values decreasing from Glu 240±12 kPa to SDS 210±6 kPa and EtAc 140±3 kPa, P<.001. Relative to glutaraldehyde treatments, neutrophil adhesion to the decellularized grafts increased, with no statistical difference observed between SDS or EtAc treatments. Early platelet adhesion (% surface coverage) showed no statistical difference between the three treatments; however, quantification of platelet aggregates was significantly higher on SDS scaffolds compared to EtAc or Glu. Tissue processing strategies applied to the umbilical vein scaffold were shown to modify structural mechanics and cell adhesion properties, with the EtAc treatment reducing thrombotic events relative to SDS treated samples. This approach allows time and cost effective prescreening of clinically relevant grafting materials to assess initial cell reactivity. PMID:26322140

  15. Processing, mechanical behavior and biocompatibility of ultrafine grained zirconium fabricated by accumulative roll bonding

    NASA Astrophysics Data System (ADS)

    Jiang, Ling

    The aim of this study is to produce large quantities of bulk zirconium with an ultrafine grained microstructure and with enhanced properties. Accumulative roll bonding (ARB), a severe plastic deformation technique based on rolling, is chosen due to its availability in industrial environment. The texture, microstructure and mechanical behavior of bulk ultrafine grained (ufg) Zr fabricated by accumulative roll bonding is investigated by electron backscatter diffraction, transmission electron microscopy and mechanical testing. A reasonably homogeneous and equiaxed ufg structure, with a large fraction of high angle boundaries (HABs, ˜70%), can be obtained in Zr after only two ARB cycles. The average grain size, counting only HABs (theta>15°), is 400 nm. (Sub)grain size is equal to 320 nm. The yield stress and ultimate tensile stress (UTS) values are nearly double those from conventionally processed Zr with only a slight loss of ductility. Optimum processing conditions include large thickness reductions per pass (˜75%), which enhance grain refinement, and a rolling temperature (T ˜ 0.3Tm) at which a sufficient number of slip modes are activated, with an absence of significant grain growth. Grain refinement takes place by geometrical thinning and grain subdivision by the formation of geometrically necessary boundaries. The formation of equiaxed grains by geometric dynamic recrystallization is facilitated by enhanced diffusion due to adabatic heating. Optical microscopy examination and shear testing suggest accepted bonding quality compared to that achieved in materials processed by diffusion bonding and that obtained in other ARB studies. Biocompatibility of ultrafine grained Zr processed by large strain rolling is studied by evaluating the behavior of human osteoblast cells. It is suggested that ultrafine grained Zr has a similar good biocompatibility as Ti6Al4V alloy and conventional Zr with a large grain size have. The improved mechanical properties together with an excellent biocompatibility make ultrafine grained Zr a promising biomaterial for surgical implants.

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

    E-print Network

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

    2012-07-09

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

  17. Inactivation mechanisms of pathogenic bacteria in several matrixes during the composting process in a composting toilet.

    PubMed

    Sossou, S K; Hijikata, N; Sou, M; Tezuka, R; Maiga, A H; Funamizu, N

    2014-01-01

    This study aimed to compare the inactivation rate and the mechanisms of pathogenic bacteria in three matrixes (sawdust, rice husk and charcoal) during the composting process. The inactivation rate was evaluated with Escherichia coli strain and the damaged parts and/or functions were evaluated with three different media. Normalized inactivation rate constant in three media and from three matrixes had no significant difference in each process (pure, 1 month and 2 months). The value in rice husk was relatively increased during 2 months but there was no significant difference. The inactivation rate constants of Tryptic Soy Agar (TSA) and Compact Dry E. coli/Coliform in pure sawdust and rice husk were relatively lower than that of Desoxycholate Agar, but increased in 2 months. This indicated that damaging part was changed from outer membrane to enzymes and metabolisms during the 2-month composting process. In the case of charcoal, only the TSA value in apure matrix was relatively lower than that of others, but it increased in 2 months. This indicated that damaging part was changed from outer membrane and enzyme to metabolisms during the composting process. Composting matrix and composting process did not significantly affect inactivation rate of pathogenic bacteria during the process but affected the damaging part of the bacteria. PMID:24645447

  18. Optical Trap Kits: Issues to Be Aware of

    ERIC Educational Resources Information Center

    Alexeev, I.; Quentin, U.; Leitz, K. -H.; Schmidt, M.

    2012-01-01

    An inexpensive and robust optical trap system can be built from off-the-shelf optical and opto-mechanical components or acquired as a kit to be assembled in a laboratory. The primary advantages of such a trap, besides being significantly more affordable, are its flexibility, and ease of modification and upgrade. In this paper, we consider several…

  19. Do capture data from mosquito traps represent reality?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Collectively, the effects of mechanical trap style, the method of trap placement in the field, mosquito activity phase, and other biological phenomena are manifest as sample bias that leads to vector detection failure(s) and/or erroneous predictions of mosquito activity. The goal of this research i...

  20. The physics of hearing: fluid mechanics and the active process of the inner ear

    NASA Astrophysics Data System (ADS)

    Reichenbach, Tobias; Hudspeth, A. J.

    2014-07-01

    Most sounds of interest consist of complex, time-dependent admixtures of tones of diverse frequencies and variable amplitudes. To detect and process these signals, the ear employs a highly nonlinear, adaptive, real-time spectral analyzer: the cochlea. Sound excites vibration of the eardrum and the three miniscule bones of the middle ear, the last of which acts as a piston to initiate oscillatory pressure changes within the liquid-filled chambers of the cochlea. The basilar membrane, an elastic band spiraling along the cochlea between two of these chambers, responds to these pressures by conducting a largely independent traveling wave for each frequency component of the input. Because the basilar membrane is graded in mass and stiffness along its length, however, each traveling wave grows in magnitude and decreases in wavelength until it peaks at a specific, frequency-dependent position: low frequencies propagate to the cochlear apex, whereas high frequencies culminate at the base. The oscillations of the basilar membrane deflect hair bundles, the mechanically sensitive organelles of the ear's sensory receptors, the hair cells. As mechanically sensitive ion channels open and close, each hair cell responds with an electrical signal that is chemically transmitted to an afferent nerve fiber and thence into the brain. In addition to transducing mechanical inputs, hair cells amplify them by two means. Channel gating endows a hair bundle with negative stiffness, an instability that interacts with the motor protein myosin-1c to produce a mechanical amplifier and oscillator. Acting through the piezoelectric membrane protein prestin, electrical responses also cause outer hair cells to elongate and shorten, thus pumping energy into the basilar membrane's movements. The two forms of motility constitute an active process that amplifies mechanical inputs, sharpens frequency discrimination, and confers a compressive nonlinearity on responsiveness. These features arise because the active process operates near a Hopf bifurcation, the generic properties of which explain several key features of hearing. Moreover, when the gain of the active process rises sufficiently in ultraquiet circumstances, the system traverses the bifurcation and even a normal ear actually emits sound. The remarkable properties of hearing thus stem from the propagation of traveling waves on a nonlinear and excitable medium.

  1. Origin of green emission and charge trapping dynamics in ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Li, Mingjie; Xing, Guichuan; Xing, Guozhong; Wu, Bo; Wu, Tom; Zhang, Xinhai; Sum, Tze Chien

    2013-03-01

    The origins of the commonly observed green emission (GE) from ZnO nanostructures remain highly controversial despite extensive studies over the past few decades. Herein, through a comprehensive ultrafast optical spectroscopy study, new insights into its origin and the charge trapping dynamics at the GE centers in ZnO nanowires prepared by the vapor transport method are gained. Transient absorption spectroscopy (TAS) revealed a sub-band-gap absorption bleaching band arising from the state filling of the electrons in the conduction band and holes trapped in the GE centers. The GE originates from the recombination between the electrons in the conduction band and/or shallow donor levels and the holes trapped at the GE centers (which are located at ˜0.88 eV above the valence band). Importantly, an ultrafast excitonic Auger-type hole trapping process to the GE centers occurring in a subpicosecond time scale was also uncovered by TAS—shedding new light on the mechanism behind the fast and efficient charge trapping of photoexcited carriers. The knowledge gained is crucial for the development of ZnO-based optoelectronic devices.

  2. Physiological evidence for a temporal processing mechanism underlying voice-onset time (VOT) encoding

    NASA Astrophysics Data System (ADS)

    Steinschneider, Mitchell; Fishman, Yonatan I.; Volkov, Igor O.; Howard, Matthew A.

    2001-05-01

    Despite decades of psychoacoustical research, the detailed neural mechanisms underlying VOT encoding remain obscure. Evidence collected from direct recordings in auditory cortex of human subjects undergoing surgical evaluation for medically intractable epilepsy, and from primary auditory cortex in monkeys, supports a temporal processing mechanism as a principal means by which VOT is encoded by the brain. This mechanism, as proposed by Pisoni [J. Acoust. Soc. Am. 77, 1352-1361 (1977)], argues that the perceptual discrimination of voiced from unvoiced stop consonants is based, in part, on whether consonant release and voicing onset are perceived as occurring simultaneously or sequentially. Neural activity in auditory cortex offers physiologically plausible parallels to this perceptual scheme that can help account for the distribution of typical VOT values used by the majority of the world's languages, categorical perception of VOT, and perceptual boundary shifts that occur with changes in stop-consonant place of articulation and when nonspeech analogs of VOT are used. These responses in primary auditory cortex are poised to provide powerful inputs to later processing areas, where they can be integrated with other acoustical, visual, and language-related inputs known to modulate VOT perception. [Work supported by DC00657 and DC00120.

  3. Graphics processing units as tools to predict mechanisms of biological signaling pathway regulation

    NASA Astrophysics Data System (ADS)

    McCarter, Patrick; Elston, Timothy; Nagiek, Michal; Dohlman, Henrik

    2013-04-01

    Biochemical and genomic studies have revealed protein components of S. cerevisiae (yeast) signal transduction networks. These networks allow the transmission of extracellular signals to the cell nucleus through coordinated biochemical interactions, resulting in direct responses to specific external stimuli. The coordination and regulation mechanisms of proteins in these networks have not been fully characterized. Thus, in this work we develop systems of ordinary differential equations to characterize processes that regulate signaling pathways. We employ graphics processing units (GPUs) in high performance computing environments to search in parallel through substantially more comprehensive parameter sets than allowed by personal computers. As a result, we are able to parameterize larger models with experimental data, leading to an increase in our model prediction capabilities. Thus far these models have helped to identify specific mechanisms such as positive and negative feedback loops that control network protein activity. We ultimately believe that the use of GPUs in biochemical signal transduction pathway modeling will help to discern how regulation mechanisms allow cells to respond to multiple external stimuli.

  4. Influence of Process Parameters on the Mechanical Behavior of an Ultrafine-Grained Al Alloy

    NASA Astrophysics Data System (ADS)

    Topping, Troy D.; Ahn, Byungmin; Li, Ying; Nutt, Steven R.; Lavernia, Enrique J.

    2012-02-01

    Aluminum alloys with nanocrystalline (NC) and ultrafine grain (UFG) size are of interest because of their strengths that are typically 30 pct greater than conventionally processed alloys of the same composition. In this study, UFG AA 5083 plate was prepared by quasi-isostatic (QI) forging of cryomilled powder, and the microstructure and mechanical behavior was investigated and compared with the behavior of coarse-grained AA 5083. Forging parameters were adjusted in an effort to strengthen the UFG material while retaining some tensile ductility. Different forging parameters were employed on three plates, with approximate dimensions of 254 mm diameter and 19 mm thickness. The overarching goal of the current effort was to increase strength through minimized grain growth during processing while maintaining ductility by breaking up prior particle boundaries (PPBs) with high forging pressures. Mechanical tests revealed that strength increased inversely with grain size, whereas ductility for some of the experimental materials was preserved at the level of the conventional alloy. The application of the Hall-Petch relationship to the materials was studied and is discussed in detail with consideration given to strengthening mechanisms other than grain size, including dispersion (Orowan), solid solution, and dislocation strengthening.

  5. 50 CFR 697.19 - Trap limits and trap tag requirements for vessels fishing with lobster traps.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...limits and trap tag requirements for vessels fishing with lobster traps. 697.19 Section...limits and trap tag requirements for vessels fishing with lobster traps. (a) Trap limits for vessels fishing or authorized to fish in any...

  6. 50 CFR 697.19 - Trap limits and trap tag requirements for vessels fishing with lobster traps.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...limits and trap tag requirements for vessels fishing with lobster traps. 697.19 Section...limits and trap tag requirements for vessels fishing with lobster traps. (a) Trap limits for vessels fishing or authorized to fish in any...

  7. Nanostructured tapered optical fibers for paticle trapping

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    Optical micro- and nanofibers have recently gained popularity as tools in quantum engineering using laser-cooled, neutral atoms. In particular, atoms can be trapped around such optical fibers, and photons coupled into the fibers from the surrounding atoms could be used to transfer quantum state information within the system. It has also been demonstrated that such fibers can be used to manipulate and trap silica and polystyrene particles in the 1-3 ?m range. We recently proposed using a focused ion beam nanostructured tapered optical fiber for improved atom trapping geometries1. Here, we present details on the design and fabrication of these nanostructured optical fibers and their integration into particle trapping platforms for the demonstration of submicron particle trapping. The optical fibers are tapered to approximately 1-2 ?m waist diameters, using a custom-built, heat-and-pull fiber rig, prior to processing using a focused ion beam. Slots of about 300 nm in width and 10-20 ?m in length are milled right though the waist regions of the tapered optical fibers. Details on the fabrication steeps necessary to ensure high optical transmission though the fiber post processing are included. Fiber transmissions of over 80% over a broad range of wavelengths, in the 700-11100 nm range, are attainable. We also present simulation results on the impact of varying the slot parameters on the trap depths achievable and milling multiple traps within a single tapered fiber. This work demonstrates even further the functionality of optical micro- and nanofibers as trapping devices across a range of regimes.

  8. Immune function across generations: integrating mechanism and evolutionary process in maternal antibody transmission.

    PubMed Central

    Grindstaff, Jennifer L; Brodie, Edmund D; Ketterson, Ellen D

    2003-01-01

    The past 30 years of immunological research have revealed much about the proximate mechanisms of maternal antibody transmission and utilization, but have not adequately addressed how these issues are related to evolutionary and ecological theory. Much remains to be learned about individual differences within a species in maternal antibody transmission as well as differences among species in transmission or utilization of antibodies. Similarly, maternal-effects theory has generally neglected the mechanisms by which mothers influence offspring phenotype. Although the environmental cues that generate maternal effects and the consequent effects for offspring phenotype are often well characterized, the intermediary physiological and developmental steps through which the maternal effect is transmitted are generally unknown. Integration of the proximate mechanisms of maternal antibody transmission with evolutionary theory on maternal effects affords an important opportunity to unite mechanism and process by focusing on the links between genetics, environment and physiology, with the ultimate goal of explaining differences among individuals and species in the transfer of immune function from one generation to the next. PMID:14667346

  9. Sub-Doppler laser cooling and magnetic trapping of erbium

    E-print Network

    Andrew J. Berglund; Siu Au Lee; Jabez J. McClelland

    2008-02-06

    We investigate cooling mechanisms in magneto-optically and magnetically trapped erbium. We find efficient sub-Doppler cooling in our trap, which can persist even in large magnetic fields due to the near degeneracy of two Lande g factors. Furthermore, a continuously loaded magnetic trap is demonstrated where we observe temperatures below 25 microkelvin. These favorable cooling and trapping properties suggest a number of scientific possibilities for rare-earth atomic physics, including narrow linewidth laser cooling and spectroscopy, unique collision studies, and degenerate bosonic and fermionic gases with long-range magnetic dipole coupling.

  10. Heating of trapped ultracold atoms by collapse dynamics

    NASA Astrophysics Data System (ADS)

    Laloë, Franck; Mullin, William J.; Pearle, Philip

    2014-11-01

    The continuous spontaneous localization (CSL) theory alters the Schrödinger equation. It describes wave-function collapse as a dynamical process instead of an ill-defined postulate, thereby providing macroscopic uniqueness and solving the so-called measurement problem of standard quantum theory. CSL contains a parameter ? giving the collapse rate of an isolated nucleon in a superposition of two spatially separated states and, more generally, characterizing the collapse time for any physical situation. CSL is experimentally testable, since it predicts some behavior different from that predicted by standard quantum theory. One example is the narrowing of wave functions, which results in energy imparted to particles. Here we consider energy given to trapped ultracold atoms. Since these are the coldest samples under experimental investigation, it is worth inquiring how they are affected by the CSL heating mechanism. We examine the CSL heating of a Bose-Einstein condensate (BEC) in contact with its thermal cloud. Of course, other mechanisms also provide heat and also particle loss. From varied data on optically trapped cesium BECs, we present an energy audit for known heating and loss mechanisms. The result provides an upper limit on CSL heating and thereby an upper limit on the parameter ? . We obtain ? ?1 (±1 ) ×10-7 s-1.

  11. Error awareness and salience processing in the oddball task: shared neural mechanisms.

    PubMed

    Harsay, Helga A; Spaan, Marcus; Wijnen, Jasper G; Ridderinkhof, K Richard

    2012-01-01

    A body of work suggests similarities in the way we become aware of an error and process motivationally salient events. Yet, evidence for a shared neural mechanism has not been provided. A within subject investigation of the brain regions involved in error awareness and salience processing has not been reported. While the neural response to motivationally salient events is classically studied during target detection after longer target-to-target intervals in an oddball task and engages a widespread insula-thalamo-cortical brain network, error awareness has recently been linked to, most prominently, anterior insula cortex. Here we explore whether the anterior insula activation for error awareness is related to salience processing, by testing for activation overlap in subjects undergoing two different task settings. Using a within subjects design, we show activation overlap in six major brain areas during aware errors in an antisaccade task and during target detection after longer target-to-target intervals in an oddball task: anterior insula, anterior cingulate, supplementary motor area, thalamus, brainstem, and parietal lobe. Within subject analyses shows that the insula is engaged in both error awareness and the processing of salience, and that the anterior insula is more involved in both processes than the posterior insula. The results of a fine-grained spatial pattern overlap analysis between active clusters in the same subjects indicates that even if the anterior insula is activated for both error awareness and salience processing, the two types of processes might tend to activate non-identical neural ensembles on a finer-grained spatial level. Together, these outcomes suggest a similar functional phenomenon in the two different task settings. Error awareness and salience processing share a functional anatomy, with a tendency toward subregional dorsal and ventral specialization within the anterior insula. PMID:22969714

  12. Distinct cognitive mechanisms involved in the processing of single objects and object ensembles

    PubMed Central

    Cant, Jonathan S.; Sun, Sol Z.; Xu, Yaoda

    2015-01-01

    Behavioral research has demonstrated that the shape and texture of single objects can be processed independently. Similarly, neuroimaging results have shown that an object's shape and texture are processed in distinct brain regions with shape in the lateral occipital area and texture in parahippocampal cortex. Meanwhile, objects are not always seen in isolation and are often grouped together as an ensemble. We recently showed that the processing of ensembles also involves parahippocampal cortex and that the shape and texture of ensemble elements are processed together within this region. These neural data suggest that the independence seen between shape and texture in single-object perception would not be observed in object-ensemble perception. Here we tested this prediction by examining whether observers could attend to the shape of ensemble elements while ignoring changes in an unattended texture feature and vice versa. Across six behavioral experiments, we replicated previous findings of independence between shape and texture in single-object perception. In contrast, we observed that changes in an unattended ensemble feature negatively impacted the processing of an attended ensemble feature only when ensemble features were attended globally. When they were attended locally, thereby making ensemble processing similar to single-object processing, interference was abolished. Overall, these findings confirm previous neuroimaging results and suggest that distinct cognitive mechanisms may be involved in single-object and object-ensemble perception. Additionally, they show that the scope of visual attention plays a critical role in determining which type of object processing (ensemble or single object) is engaged by the visual system. PMID:26360156

  13. Improvement of mechanical properties and life extension of high reliability structural components by laser shock processing

    NASA Astrophysics Data System (ADS)

    Ocaña, J. L.; Morales, M.; Porro, J. A.; Iordachescu, D.; Díaz, M.; Ruiz de Lara, L.; Correa, C.

    2011-05-01

    Profiting by the increasing availability of laser sources delivering intensities above 109 W/cm2 with pulse energies in the range of several Joules and pulse widths in the range of nanoseconds, laser shock processing (LSP) is being consolidating as an effective technology for the improvement of surface mechanical and corrosion resistance properties of metals and is being developed as a practical process amenable to production engineering. The main acknowledged advantage of the laser shock processing technique consists on its capability of inducing a relatively deep compression residual stresses field into metallic alloy pieces allowing an improved mechanical behaviour, explicitly, the life improvement of the treated specimens against wear, crack growth and stress corrosion cracking. Following a short description of the theoretical/computational and experimental methods developed by the authors for the predictive assessment and experimental implementation of LSP treatments, experimental results on the residual stress profiles and associated surface properties modification successfully reached in typical materials (specifically Al and Ti alloys) under different LSP irradiation conditions are presented. In particular, the analysis of the residual stress profiles obtained under different irradiation parameters and the evaluation of the corresponding induced surface properties as roughness and wear resistance are presented.

  14. The Role of Mitochondria in Cellular Iron–Sulfur Protein Biogenesis: Mechanisms, Connected Processes, and Diseases

    PubMed Central

    Stehling, Oliver; Lill, Roland

    2013-01-01

    Iron–sulfur (Fe/S) clusters belong to the most ancient protein cofactors in life, and fulfill functions in electron transport, enzyme catalysis, homeostatic regulation, and sulfur activation. The synthesis of Fe/S clusters and their insertion into apoproteins requires almost 30 proteins in the mitochondria and cytosol of eukaryotic cells. This review summarizes our current biochemical knowledge of mitochondrial Fe/S protein maturation. Because this pathway is essential for various extramitochondrial processes, we then explain how mitochondria contribute to the mechanism of cytosolic and nuclear Fe/S protein biogenesis, and to other connected processes including nuclear DNA replication and repair, telomere maintenance, and transcription. We next describe how the efficiency of mitochondria to assemble Fe/S proteins is used to regulate cellular iron homeostasis. Finally, we briefly summarize a number of mitochondrial “Fe/S diseases” in which various biogenesis components are functionally impaired owing to genetic mutations. The thorough understanding of the diverse biochemical disease phenotypes helps with testing the current working model for the molecular mechanism of Fe/S protein biogenesis and its connected processes. PMID:23906713

  15. Variation of thermal and mechanical properties of KMPR due to processing parameters

    NASA Astrophysics Data System (ADS)

    Reynolds, Matthew; Elias, Anastasia; Elliott, Duncan G.; Backhouse, Christopher; Sameoto, Dan

    2012-12-01

    We present a study of the thermal and mechanical properties of the negative photoresist KMPR and the influence of processing conditions on those properties. The process parameters chosen all relate to the cross-linking level of the photoresist: the UV exposure dose, the baking temperature and the bake length. The stability of KMPR at high temperatures was also examined. The glass transition temperature was measured using dynamic mechanical analysis, with a maximum measured value of 128 °C achieved in our tests. Relating the glass transition temperature to the cross-linking level of the material, exposure doses higher than 2 J cm-2 were shown to have a negligible effect on the cross-linking (for 80 ?m thick films). Using thermogravitmetric analysis, KMPR has been shown to lose significant mass when heated above 200 °C. Young's modulus of KMPR was measured to be between 2.0 GPa for samples hard-baked at 100 °C and 2.7 GPa for samples baked at 150 and 200 °C. Creep behavior for KMPR held under strain was studied for samples prepared under a range of processing temperatures. Finally the thermally-induced cross-linking of unexposed KMPR was studied, with samples post-exposure baked at 150 °C, or 120 °C for at least an hour, cross-linking sufficiently to prevent development.

  16. High temperature mechanical properties of a multilayer Y-TZP processed by superplastic flow

    SciTech Connect

    Dominguez-Rodriguez, A.; Jimenez-Pique, E.; Jimenez-Melendo, M.

    1998-06-05

    In a previous paper the authors have described a novel technique to join fine grained ceramics, which takes advantage of the grain boundary sliding as the microscopic mechanism of the superplasticity and of the fact that the creep resistance increases with the grain size. Superplasticity is grain-size dependent, {dot {epsilon}} {approx} (1/d{sup p}), with p between 1 and 3 depending on the rate controlling process. The authors have used these two concepts as a new technique to join layers of 3% mol Y-TZP with four different grain sizes, in order to have the same thermal expansion coefficient avoiding deformation of cavities and microcracks in the interface and so to obtain a functional gradient material (FGM) with anisotropic high temperature mechanical properties.

  17. Glomerular protein separation as a mechanism for powering renal concentrating processes.

    PubMed

    Letts, Robyn F R; Rubin, David M; Louw, Robert H; Hildebrandt, Diane

    2015-08-01

    Various models have been proposed to explain the urine concentrating mechanism in mammals, however uncertainty remains regarding the origin of the energy required for the production of concentrated urine. We propose a novel mechanism for concentrating urine. We postulate that the energy for the concentrating process is derived from the osmotic potentials generated by the separation of afferent blood into protein-rich efferent blood and protein-deplete filtrate. These two streams run in mutual juxtaposition along the length of the nephron and are thus suitably arranged to provide the osmotic potential to concentrate the urine. The proposed model is able to qualitatively explain the production of various urine concentrations under different clinical conditions. An approach to testing the feasibility of the hypothesis is proposed. PMID:25935399

  18. Mechanical, thermal and optical properties of the SPS-processed polycrystalline Nd:YAG

    NASA Astrophysics Data System (ADS)

    Sokol, M.; Kalabukhov, S.; Kasiyan, V.; Rothman, A.; Dariel, M. P.; Frage, N.

    2014-12-01

    The present study deals with a comprehensive comparison of the mechanical and functional properties of Nd:YAG single crystals with those of the polycrystalline ceramics (PCs), undoped and LiF-doped, processed by Spark Plasma Sintering (SPS). The polycrystalline ceramics have higher mechanical properties (hardness, bending strength and thermal shock resistance) than the single crystals. The optical transmittance of the LiF-doped PC Nd:YAG is significantly higher than that of the undoped one and is close to that of the single crystal. With respect to other optical and thermal properties, i.e. refraction index, absorption coefficient, extinction ratio, thermo-optic coefficient, fluorescence and thermal conductivity, no significant differences were observed between the single crystals and the polycrystalline ceramic.

  19. Synthesis mechanism of heterovalent Sn2O3 nanosheets in oxidation annealing process

    NASA Astrophysics Data System (ADS)

    Zhao, Jun-Hua; Tan, Rui-Qin; Yang, Ye; Xu, Wei; Li, Jia; Shen, Wen-Feng; Wu, Guo-Qiang; Yang, Xu-Feng; Song, Wei-Jie

    2015-07-01

    Heterovalent Sn2O3 nanosheets were fabricated via an oxidation annealing process and the formation mechanism was investigated. The temperature required to complete the phase transformation from Sn3O4 to Sn2O3 was considered. Two contrasting experiments showed that both oxygen and heating were not necessary conditions for the phase transition. Sn2O3 was formed under an argon protective atmosphere by annealing and could also be obtained at room temperature by exposing Sn3O4 in atmosphere or dispersing in ethanol. The synthesis mechanism was proposed and discussed. This fundamental research is important for the technological applications of intermediate tin oxide materials. Project supported by the National Natural Science Foundation of China (Grant Nos. 21377063, 51102250, 21203226, and 21205127) and the Personnel Training Foundation of Quzhou University, China (Grant No. BSYJ201412).

  20. [Removal characteristics and mechanism of Cryptosporidium and Giardia from secondary effluent in flocculation process].

    PubMed

    Zhang, Tong; Hu, Hong-ying; Xie, Xing; Zong, Zu-sheng

    2008-08-01

    Removal of Cryptosporidium and Giardia under different reaction conditions, such as flocculent dosage, pH, temperature, were investigated to study the removal characteristic and mechanism of pathogenic protozoan in a flocculation process. The experimental results showed that after flocculation, there were not good linear relationships between average t potential of colloid in water samples and removal efficiency of the two kinds of microspheres, the surrogates of the pathogenic protozoan, or the residual turbidity (R = 0.49, 0.48, 0.65). But the linear relationship between the removal of the two kinds of microspheres was obvious (R = 0.99), and there were also good exponential relationships between the removal of microspheres and residual turbidity (R = 0.92,0.95). Sweep flocculation appeared to be an important mechanism for protozoan removal under the conditions in this study. The removal efficiency of Giardia was higher than that of Cryptosporidium under same reaction conditions. PMID:18839587