These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

2

Actin filament mechanics in the laser trap  

Microsoft Academic Search

Summary Numerous biological processes, including muscular contraction, depend upon the mechanical 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' captured in independent laser traps. The positions of the traps were manipulated to apply a range of tensions (0-8

D. E. D UPUIS; D. M. W ARSHAW

1997-01-01

3

Actin filament mechanics in the laser trap  

Microsoft Academic Search

Numerous biological processes, including muscular contraction, depend upon the mechanical properties of actin filaments. One\\u000a such property is resistance to bending (flexural rigidity, EI). To estimate EI, we attached the ends of fluorescently labelled\\u000a actin filaments to two microsphere‘handles’ captured in independent laser traps. The positions of the traps were manipulated\\u000a to apply a range of tensions (0--8 pN)to the

D. E. DUPUIS; W. H. GUILFORD; J. WU; D. M. WARSHAW

1997-01-01

4

Trapped Atomic Ions and Quantum Information Processing  

NASA Astrophysics Data System (ADS)

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, Schrödinger'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.

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.; Knill, M.; Koelemeij, J. C. J.; Langer, C.; Ozeri, R.; Reichle, R.; Rosenband, T.; Schaetz, T.; Schmidt, P. O.; Seidelin, S.; Shiga, N.; Wesenberg, J. H.

2006-11-01

5

Molten Hydroxide Trapping Process for Radioiodine  

SciTech Connect

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.

Trowbridge, L.D.

2003-01-28

6

CO2 Capillary-Trapping Processes in Deep Saline Aquifers  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

7

Process Tomography of Ion Trap Quantum Gates  

Microsoft Academic Search

A crucial building block for quantum information processing with trapped ions is a controlled-NOT quantum gate. In this Letter, two different sequences of laser pulses implementing such a gate operation are analyzed using quantum process tomography. Fidelities of up to 92.6(6)% are achieved for single-gate operations and up to 83.4(8)% for two concatenated gate operations. By process tomography we assess

M. Riebe; K. Kim; P. Schindler; T. Monz; P. O. Schmidt; T. K. Körber; W. Hänsel; H. Häffner; C. F. Roos; R. Blatt

2006-01-01

8

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

SciTech Connect

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.

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

2010-03-15

9

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

NASA Astrophysics Data System (ADS)

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.

Abe, K.; Hasegawa, T.

2010-03-01

10

Quantum Information Processing with Trapped Ions*  

NASA Astrophysics Data System (ADS)

Trapped strings of cold ions provide an ideal system for quantum information processing. The quantum information can be stored in individual ions and these qubits can be individually prepared, the corresponding quantum states can be manipulated and measured with nearly 100% detection efficiency. With a small ion-trap quantum computer based on two and three trapped Ca^+ ions as qubits we have generated in a pre-programmed way genuine quantum states. In particular, entangled states of two particles, i.e. Bell states [1], and of three particles, i.e. GHZ and W states [2], were generated using an algorithmic procedure and their decoherence was investigated. These states are of particular interest for the implementation of a three-ion quantum register: we have demonstrated selective read-out of single qubits (while protecting the other qubits) and manipulation of single qubits of the register conditioned on the read-out results. The generated states have been measured experimentally using a technique known as state tomography allowing the population and phase of the quantum system to be mapped. Moreover, quantum teleportation with trapped ions was implemented [3] and can be used as resource for the transfer of quantum information as well as for quantum information processing. *Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria, and Institut für Quantenoptik und Quanteninformation, "Osterreichische Akademie der Wissenschaften, Technikerstraße 25, A-6020 Innsbruck, Austria. *C. F. Roos et al., Phys. Rev. Lett. 92, 220402 (2004). *C. F. Roos et al., Science 304, 1478 (2004). *M. Riebe et al., Nature 429, 734 (2004).

Koerber, Timo

2005-05-01

11

New Trapping Mechanism in Carbon Sequestration  

Microsoft Academic Search

The modes of geologic storage of CO2 are usually categorized as structural, dissolution, residual, and mineral trapping. Here we argue that the heterogeneity\\u000a intrinsic to sedimentary rocks gives rise to a fifth category of storage, which we call local capillary trapping. Local capillary\\u000a trapping occurs during buoyancy-driven migration of bulk phase CO2 within a saline aquifer. When the rising CO2

Ehsan Saadatpoor; Steven L. Bryant; Kamy Sepehrnoori

2010-01-01

12

TRANSIENT QUANTUM MECHANICAL PROCESSES  

SciTech Connect

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.

L. COLLINS; J. KRESS; R. WALKER

1999-07-01

13

Trapped rubber processing for advanced composites  

NASA Technical Reports Server (NTRS)

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.

Marra, P. J.

1976-01-01

14

Trapping mechanism in overdamped ratchets with quenched noise.  

PubMed

A trapping mechanism is observed and proposed as the origin of the anomalous behavior recently discovered in transport properties of overdamped ratchets subject to an external oscillatory drive in the presence of quenched noise. In particular, this mechanism is shown to appear whenever the quenched disorder strength is greater than a threshold value. The minimum disorder strength required for the existence of traps is determined by studying the trap structure in a disorder configuration space. An approximation to the trapping probability density function in a disordered region of finite length included in an otherwise perfect ratchet lattice is obtained. The mean velocity of the particles and the diffusion coefficient are found to have a nonmonotonic dependence on the quenched noise strength due to the presence of the traps. PMID:17677016

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

2007-05-01

15

Quantum information processing with trapped ion chains  

NASA Astrophysics Data System (ADS)

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

Manning, Timothy Andrew

16

Ion-trap quantum information processing: experimental status  

E-print Network

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.

D. Kielpinski

2008-05-16

17

Chapter 9: Quantum Information Processing with Trapped Ions  

NASA Astrophysics Data System (ADS)

Trapped ions constitute a well-isolated small quantum system that offers low decoherence rates and excellent opportunities for quantum control and measurement by laser-induced manipulation of the ions. These properties make trapped ions an attractive system for experimental investigations of quantum information processing. In this chapter, the basics of storing, manipulating and measuring quantum information encoded in a string of trapped ions will be discussed.

Roos, Christian F.

2014-01-01

18

Ion funnel ion trap and process  

DOEpatents

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.

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

19

Mechanisms of kinetic trapping in self-assembly and phase transformation  

PubMed Central

In self-assembly processes, kinetic trapping effects often hinder the formation of thermodynamically stable ordered states. In a model of viral capsid assembly and in the phase transformation of a lattice gas, we show how simulations in a self-assembling steady state can be used to identify two distinct mechanisms of kinetic trapping. We argue that one of these mechanisms can be adequately captured by kinetic rate equations, while the other involves a breakdown of theories that rely on cluster size as a reaction coordinate. We discuss how these observations might be useful in designing and optimising self-assembly reactions. PMID:21932884

Hagan, Michael F.; Elrad, Oren M.; Jack, Robert L.

2011-01-01

20

Process-dependent residual trapping of CO2 in sandstone  

NASA Astrophysics Data System (ADS)

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.

Zuo, Lin; Benson, Sally M.

2014-04-01

21

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

E-print Network

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 ...

Leibrandt, David R.

22

Efficiency of trapping processes in regular and disordered networks  

NASA Astrophysics Data System (ADS)

We use a Markov method to study the efficiency of trapping processes involving both a random walker and a deep trap in regular and disordered networks. The efficiency is gauged by the mean absorption time (average of the mean number of steps performed by the random walker before being absorbed by the trap). We compute this quantity in terms of different control parameters, namely, the length of the walker jumps, the mobility of the trap, and the degree of spatial disorder of the network. For a proper choice of the system size, we find in all cases a nonmonotonic behavior of the efficiency in terms of the corresponding control parameter. We thus arrive at the conclusion that, despite the decrease of the effective system size underlying the increase of the control parameter, the efficiency is reduced as a result of an increase of the escape probability of the walker once it finds itself in the interaction zone of the trap. This somewhat anti-intuitive effect is very robust in the sense that it is observed regardless of the specific choice of the control parameter. For the case of a ring lattice, results for the mean absorption time in systems of arbitrary size are given in terms of a two-parameter scaling function. For the case of a mobile trap, we deal with both trapping via a single channel (walker-trap overlap) and via two channels (walker-trap overlap and walker-trap crossing), thereby generalizing previous work. As for the disordered case, our analysis concerns small world networks, for which we see several crossovers of the absorption time as a function of the control parameter and the system size. The methodology used may be well suited to exploring characteristic time scales of encounter-controlled phenomena in networks with a few interacting elements and the effect of geometric constraints in nanoscale systems with a very small number of particles.

García Cantú, A.; Abad, E.

2008-03-01

23

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

E-print Network

Actin filament mechanics in the laser trap D. E. DUPUIS1 , 2 , W. H. GUILFORD1 , J. WU3 and D. M' captured in independent laser traps. The positions of the traps were manipulated to apply a range laser traps, measurements of unitary molecular events (e.g. myosin displacement) may be significantly

Guilford, William

24

Theory and Simulation of Neoclassical Transport Processes, with Local Trapping  

E-print Network

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

California at San Diego, University of

25

Solution-processed polymer photodetectors with trap-assisted photomultiplication  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

26

Photocarrier transport and trapping processes in doped polyethylene terephthalate films  

SciTech Connect

The radiation-induced conductivity of polyethylene terephthalate film is modified by doping this polymer with electron acceptor molecules. Detailed results of x-ray induced thermally stimulated current and photoconductivity experiments are reported for one dopant, 2, 4, 7-trinitro-9-fluorenone. At dopant concentrations< or approx. =10/sup 19/ molecules/cm/sup 3/, this impurity acts as a deep trap for photocarriers, radically decreasing the radiation-induced conductivity of the doped film. The kinetics of photocarrier trapping in a host material exhibiting dispersive transport is discussed. At dopant concentrations > or approx. =10/sup 20/ molecules/cm/sup 3/, the radiation-induced conductivity increases due to the onset of photocarrier transport among the electron acceptor molecules. Utilizing the physical processes discussed in this work, it is possible to develop dielectric materials displaying selected levels of radiation-induced conductivity.

Kurtz, S.R.; Arnold, C. Jr.

1985-04-01

27

Photoionization of strontium for trapped-ion quantum information processing  

E-print Network

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.

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

2006-07-07

28

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

E-print Network

are carnivorous plants living in environments poor in nutrients. Their trapping mechanism has fascinated scattered firing times. Some ``bursting'' traps even combine both aspects, with groups of fast regular.marmottant@ujf-grenoble.fr Introduction Aquatic species from the genus Utricularia are widespread carnivorous plants, catching their preys

Paris-Sud XI, Université de

29

Mechanical Systems Signal Processing  

E-print Network

­171 Multivariate statistics process control for dimensionality reduction in structural assessment L.E. Mujicaa,�, J) for reducing dimensionality in damage identification problem, in particular, detecting and locating impacts in a part of a commercial aircraft wing flap. It is shown that applying MPCA and MPLS is convenient

Verleysen, Michel

30

A mechanism study of sound wave-trapping barriers.  

PubMed

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

Yang, Cheng; Pan, Jie; Cheng, Li

2013-09-01

31

Hydrodynamic mechanisms of cell and particle trapping in microfluidics  

PubMed Central

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

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

2013-01-01

32

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

PubMed Central

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

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

2013-01-01

33

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

PubMed

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

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

2013-01-01

34

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

PubMed Central

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

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

2013-01-01

35

Studies of lipid vesicle mechanics using an optical fiber dual-beam trap  

NASA Astrophysics Data System (ADS)

Fiber-based optical traps can be used for manipulating micron-sized dielectric particles such as microspheres and biological cells. Here we study the mechanics of giant unilamellar vesicles (GUVs) which are held and stretched by light forces in a fiber-based dual-beam optical trap. Our GUVs are suspended in a buffer solution and encapsulate various concentrations and molecular weights of poly(ethylene glycol) (PEG) polymer yielding a range of refractive index contrasts and trapping conditions. We find that we can trap GUVs in solution with index contrasts of less than 0.01. We explore the mechanical response of the GUV membrane to a range of forces which are proportional to laser power and refractive index contrast. Our trapping system is a compact and inexpensive platform and trapping is viewed in real time under a microscope. We hypothesize that forces within the high-tension regime will induce a linear response in vesicle surface area. This project sets the stage for membrane mechanics and lipid phase change studies.

Pinon, Tessa M.; Hirst, Linda S.; Sharping, Jay E.

2011-03-01

36

Mechanism of DNA trapping in nanoporous structures during asymmetric pulsed-field electrophoresis.  

PubMed

We investigate the trapping mechanism of individual DNA molecules in ordered nanoporous structures generated by crystalline particle arrays. Two requisites for trapping are revealed by the dynamics of single trapped DNA, fully-stretched U/J shapes and hernia formation. The experimental results show there is a stronger possibility for hernias to lead the reorientation upon switching directions of the voltage at high field strengths, where trapping occurs. Fully stretched DNA has longer unhooking times than expected by a classic rope-on-pulley model. We propose a dielectrophoretic (DEP) force reduces the mobility of segments at the apex of the U or J, where field gradients are highest, based on simulations and observations of the trapping force dependence on field strength. A modified model for unhooking time is obtained after the DEP force is introduced. The new model explains the unhooking time data by predicting an infinite trapping time when the ratio of arm length differences (of the U or J) to molecule length ?x/L < ?, where ? is a DEP parameter that is found to strongly increase with electric field. The DNA polarizability calculated with the DEP model and experimental value of ? is of the same magnitude of reported value. The results indicate the tension at the apex of U/J shape DNA is the primary reason for DNA trapping during pulsed field separation, instead of hernias. PMID:25271806

Zhou, Ya; Sheng, Huiying; Harrison, D Jed

2014-11-21

37

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

PubMed

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

Proulx, G; Barrett, M W

1993-04-01

38

Study of hepatocyte plasma membrane mechanical properties using optical trapping  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

39

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...

40

Bacillus subtilis TRAP binds to its RNA target by a 5' to 3' directional mechanism.  

PubMed

TRAP is an 11 subunit RNA-binding protein that regulates expression of the Bacillus subtilis trpEDCFBA operon by transcription attenuation and translation control mechanisms. Tryptophan-activated TRAP acts by binding to a site in the 5'-untranslated leader region of trp mRNA consisting of 11 (G/U)AG repeats. We used mung bean nuclease footprinting to analyze the interaction of TRAP with several artificial binding sites composed of 11 GAG repeats in nucleic acids that lack secondary structure. Affinities for individual repeats within a binding site did not vary significantly. In contrast, the association rate constants were highest for repeats at the 5' end and lowest for those at the 3' end of all binding sites tested. These results indicate that TRAP binds to its RNA targets by first associating with one or more repeat at the 5' end of its binding site followed by wrapping the remainder of binding site around the protein in a 5' to 3' direction. This directional binding is novel among RNA-binding proteins. We suggest that this mechanism of binding is important for TRAP-mediated transcription attenuation control of the trp operon. PMID:15588817

Barbolina, Maria V; Li, Xiufeng; Gollnick, Paul

2005-01-28

41

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

E-print Network

(Received 19 October 2010; published 18 February 2011) The underwater traps of the carnivorous plants fast suction" sequence. In this paper, we propose a mechanical model that describes both phases of carnivorous plants, which are the result of adaptation to poor environments in terms of nutriments and

Paris-Sud XI, Université de

42

Multifunctionality and mechanical origins: Ballistic jaw propulsion in trap-jaw ants  

E-print Network

Multifunctionality and mechanical origins: Ballistic jaw propulsion in trap-jaw ants S. N. Patek mandible movements serve two distinct functions: predation and propulsion. During predatory strikes, O mandible strike directed against the substrate produces sufficient propulsive power to launch the ant

Suarez, Andrew V.

43

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

Microsoft Academic Search

The rapid trap closure of Dionaea muscinula Ellis has been explained by either a loss of turgor pressure of the upper epidermis, which should thus become flexible, or by a sudden acid-induced wall loosening of the motor cells. According to our experiments both explanations are doubtful. Objections against the turgor mechanism come from the determination by extracellular measurements from the

Dieter Hodick; Andreas Sievers

1989-01-01

44

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

PubMed Central

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

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

2009-01-01

45

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

SciTech Connect

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.

Jia, Dongdong [Department of Materials Science and Engineering, Tsinghua University, Beijing, (China)] [Department of Materials Science and Engineering, Tsinghua University, Beijing, (China); Jia, Weiyi [Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681 (Puerto Rico)] [Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681 (Puerto Rico); Evans, D. R. [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States)] [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States); Dennis, W. M. [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States)] [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States); Liu, Huimin [Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681 (Puerto Rico)] [Department of Physics, University of Puerto Rico, Mayaguez, Puerto Rico 00681 (Puerto Rico); Zhu, Jing [Department of Materials Science and Engineering, Tsinghua University, Beijing, (China)] [Department of Materials Science and Engineering, Tsinghua University, Beijing, (China); Yen, W. M. [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States)] [Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602 (United States)

2000-09-15

46

The mechanics of manufacturing processes  

SciTech Connect

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

Wright, P.; Stori, J. [California Univ., Berkeley, CA (United States). Dept. of Mechanical Engineering; King, C. [Sandia National Labs., Albuquerque, NM (United States)

1996-10-01

47

Chemically assisted mechanical refrigeration process  

DOEpatents

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.

Vobach, A.R.

1987-11-24

48

Chemically assisted mechanical refrigeration process  

DOEpatents

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.

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

1987-01-01

49

Chemically assisted mechanical refrigeration process  

DOEpatents

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.

Vobach, A.R.

1987-06-23

50

Chemically assisted mechanical refrigeration process  

DOEpatents

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.

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

1987-01-01

51

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

SciTech Connect

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.

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

2006-01-01

52

Towards understanding the carbon trapping mechanism in copper by investigating the carbon—vacancy interaction  

NASA Astrophysics Data System (ADS)

We propose a vacancy trapping mechanism for carbon—vacancy (C—V) complex formation in copper (Cu) according to the first-principles calculations of the energetics and kinetics of C—V interaction. Vacancy reduces charge density in its vicinity to induce C nucleation. A monovacancy is capable of trapping as many as four C atoms to form CnV (n = 1, 2, 3, 4) complexes. A single C atom prefers to interact with neighboring Cu at a vacancy with a trapping energy of -0.21 eV With multiple C atoms added, they are preferred to bind with each other to form covalent-like bonds despite of the metallic Cu environment. For the CnV complexes, C2V is the major one due to its lowest average trapping energy (1.31 eV). Kinetically the formation of the CnV complexes can be ascribed to the vacancy mechanism due to the lower activation energy barrier and the larger diffusion coefficient of vacancy than those of the interstitial C.

Zhou, Hong-Bo; Jin, Shuo

2013-07-01

53

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

PubMed

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

Singer, Rodrigo B

2002-02-01

54

Monitoring Stored-Product Pests in Food Processing Plants with Pheromone Trapping, Contour Mapping, and Mark-Recapture  

Microsoft Academic Search

Distribution and movement patterns of severalspecies of stored-product pests in a food processing plant were investigated. The objectives of this study were to determine the temporal and spatialvariation 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

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

2002-01-01

55

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

PubMed Central

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

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

2012-01-01

56

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

57

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

PubMed

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

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

2008-10-01

58

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

SciTech Connect

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.

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

2008-06-10

59

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...

60

Aging process of I-cathode with magnetic ion trap  

Microsoft Academic Search

In this paper, the authors describe an aging process to solve the unbalanced emission slump, which does not need any change in the electron gun design. The principle is to apply a high frequency (HF) magnetic field on the electron gun during the aging process. The effect is that the scanning electron beam and the HF magnetic field heat up

Xiaobing Zhang; Wei Lei; Linsu Tong; Niangen Feng; J. Havekes; D. den Engelsen

2004-01-01

61

On the light trapping mechanism in silicon solar cells with backside diffraction gratings  

NASA Astrophysics Data System (ADS)

In this numerical study, we investigate the light trapping mechanism in silicon solar cells with backside diffraction gratings. In order to obtain a clearer view on the physical mechanisms underlying the light trapping we employ a simulation scheme that combines ray tracing with rigorous coupled wave analysis (RCWA). This combined simulation approach treats the light propagation inside the silicon absorber layer incoherently and averages out Fabry-Perot resonances, which otherwise would obscure characteristic humps in the absorption spectra that are directly related to light trapping effect of the diffraction gratings. We provide an in-depth explanation for the origin of these characteristic humps and their interrelationship with the silicon absorber thickness. A major benefit of this combined RCWA/ray tracing approach compared to the fully electromagnetic simulation methods RCWA and finite difference time domain (FDTD) is the more efficient use of computational power accompanied by a gain in simulation precision, in particular for cells with an absorber thicker than 10 ?m.

Wellenzohn, Markus; Hainberger, Rainer

2014-03-01

62

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

E-print Network

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...

Poppinga, Simon

2011-01-01

63

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

SciTech Connect

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

Mohamed, T.; Imao, H.; Mohri, A. [Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Oshima, N. [National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 2, Tsukuba, Ibaraki 305-8568 (Japan); Yamazaki, Y. [Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Institute of Physics, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902 (Japan)

2011-03-15

64

Grover-like search via a Frenkel-exciton trapping mechanism  

NASA Astrophysics Data System (ADS)

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.

Thilagam, A.

2010-03-01

65

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

NASA Technical Reports Server (NTRS)

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.

Ritchie, Stephen M. C.

2003-01-01

66

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

NASA Astrophysics Data System (ADS)

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

Allersma, Miriam W.

67

Dynamical Traps Caused by Fussy Rationality as a New Emergence Mechanism  

E-print Network

A new emergence mechanism related to the human fuzzy rationality is considered. It assumes that individuals (operators) governing the dynamics of a certain system try to follow an optimal strategy in controlling its motion but fail to do this perfectly because similar strategies are indistinguishable for them. The main attention is focused on the systems where the optimal dynamics implies the stability of a certain equilibrium point in the corresponding phase space. In such systems the fuzzy rationality gives rise to some neighborhood of the equilibrium point, the region of dynamical traps, wherein each point is regarded as an equilibrium one by the operators. So when the system enters this region and while it is located in it, maybe for a long time, the operator control is suspended. To elucidate a question as to whether the dynamical traps on their own can cause emergent phenomena the stochastic factors are eliminated from consideration. In this case the system can leave the dynamical trap region only becau...

Lubashevsky, Ihor

2011-01-01

68

Quantum many-body theory and mechanisms for low energy nuclear reaction processes in matter  

Microsoft Academic Search

Recently, a theoretical model of Bose-Einstein Condensation (BEC) mechanism has been developed to describe low-energy nuclear reaction in a quantum many-body system confined in a micro\\/nano scale trap. The BEC mechanism is applied to explain various anomalous results observed recently in experiments involved with low-energy nuclear reaction processes in matter and in acoustic cavitation. Experimental tests of the BEC mechanism

Yeong E. Kim

2004-01-01

69

Quantum Many-Body Theory and Mechanisms for Low Energy Nuclear Reaction Processes in Matter  

Microsoft Academic Search

Recently, a theoretical model of Bose-Einstein Condensation (BEC) mechanism has been developed to describe low-energy nuclear reaction in a quantum many-body system confined in a micro\\/nano scale trap. The BEC mechanism is applied to explain various anomalous results observed recently in experiments involved with low-energy nuclear reaction processes in matter and in acoustic cavitation. Experimental tests of the BEC mechanism

Y. E. Kim

2004-01-01

70

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

PubMed Central

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

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

2014-01-01

71

Kinetics and mechanisms of electrode processes  

Microsoft Academic Search

This book examines the kinetics and mechanisms of processes at electrodes and investigates the behavior of double layers at charged interfaces, the state of reacting ions in solution, and the state of solid and liquid surfaces of metals and metal oxide films with regard to their catalytic activity in various processes. Different ways of treating (at a quantum-mechanical level) the

B. E. Conway; J. O. M. Bockris; S. U. M. Khan; R. E. White; E. Yeager

1983-01-01

72

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

PubMed

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

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

2011-05-01

73

Efficient scheme for multipartite entanglement and quantum information processing with trapped ions  

NASA Astrophysics Data System (ADS)

In this paper, based on the recent experiment by Roos et al. [Science 304, 1478 (2004)], a theoretical scheme is proposed to create the multipartite entanglement of many trapped ions and implement a two-qubit quantum phase gate between two ions in ion trap. In the scheme, the ion is illuminated by a single laser tuned to the first lower vibrational sideband. We also show that the scheme can be used to directly transfer information between two ions. The scheme has the advantage that it does not use the vibrational mode as the data bus and only requires a single resonant interaction. Thus the scheme is very simple and the quantum dynamics operation can be realized at a high speed. In view of the decoherence mechanism, the simplification for the entangled state preparation and experimental implementation of quantum logic operation may become crucial.

Yang, Wen-Xing; Zhan, Zhi-Ming; Li, Jia-Hua

2005-12-01

74

Vacancy trapping mechanism for multiple hydrogen and helium in beryllium: a first-principles study  

NASA Astrophysics Data System (ADS)

The microscopic mechanism for H and He trapping by vacancy defects and bubble formation in a Be host lattice is investigated using first-principles calculations. A single He atom prefers to occupy a vacancy centre while H does not. He can segregate towards the vacancy from the interstitial site much more easily than H. Both H and He exhibit lower diffusion barriers from a remote interstitial to a vacancy with regard to their diffusion barriers inside a perfect Be solid. Up to five H or 12 He atoms can be accommodated into the monovacancy space, and the Be-He interaction is much weaker than Be-H. The physical origin for aggregation of multiple H or He atoms in a vacancy is further discussed. The strong tendency of H and He trapping at vacancies provides an explanation for why H and He bubbles were experimentally observed at vacancy defects in materials. We therefore argue that vacancies provide a primary nucleation site for bubbles of H and He gases inside Be materials.

Zhang, Pengbo; Zhao, Jijun; Wen, Bin

2012-03-01

75

Raman process under condition of radiation trapping in a disordered atomic medium  

NASA Astrophysics Data System (ADS)

We consider the Raman process developing in a disordered medium of alkali-metal atoms when the scattered modes are trapped on a closed transition. Our theoretical analysis, based on numerical simulations of the Bethe-Salpeter equation for the light correlation function, which includes all Zeeman states and light polarization, lets us track the stimulated amplification as well as the losses associated with the inverse anti-Stokes scattering channel. We discuss possible conditions when this process could approach the instability point and enter the regime of random lasing.

Gerasimov, L. V.; Ezhova, V. M.; Kupriyanov, D. V.; Baudouin, Q.; Guerin, W.; Kaiser, R.

2014-07-01

76

Effect of capillary heterogeneity on buoyant plumes: A new local trapping mechanism  

Microsoft Academic Search

CO2 can be immobilized in an aquifer as a residual phase trapped by capillary forces. The “inject low and let rise” strategy of storing CO2 in d eep saline aquifers is one method to maximize residual trapping. The more uniform the saturation front during upward movement of CO2, the greater the amount of CO2 trapped in this form. Previous studies

Ehsan Saadatpoor; Steven L. Bryant; Kamy Sepehrnoori

2009-01-01

77

Mechanics,Mechanisms and Modeling of the Chemical Mechanical Polishing Process  

E-print Network

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 ...

Noh, Kyungyoon

78

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

79

Integrated chips and optical cavities for trapped ion quantum information processing  

E-print Network

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 ...

Leibrandt, David R

2009-01-01

80

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

PubMed

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

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

2014-07-16

81

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

NASA Astrophysics Data System (ADS)

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.

Poppinga, Simon; Joyeux, Marc

2011-10-01

82

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

PubMed

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

Poppinga, Simon; Joyeux, Marc

2011-10-01

83

Kinetics and mechanisms of electrode processes  

SciTech Connect

This book examines the kinetics and mechanisms of processes at electrodes and investigates the behavior of double layers at charged interfaces, the state of reacting ions in solution, and the state of solid and liquid surfaces of metals and metal oxide films with regard to their catalytic activity in various processes. Different ways of treating (at a quantum-mechanical level) the reaction mechanics of electron and particle transfer across barriers of atomic dimensions in the double layer at electrode interfaces are discussed. Electron, proton and molecular processes from the point of activation through solvent mode fluctuations coupled with quantum-mechanical aspects of OH vibrations and hydrogen transfer; the kinetics of electrode processes that involve multistep routes; electrocatalysis; cathodic hydrogen evolution; oxygen electrode reactions to a variety of materials; electrolytic metal deposition; the semiconductor-solution interface; molten salt electrochemistry; and the application of electrode process kinetics to mechanisms of the main types of electroorganic reactions are explored. This book is recommended for those working in electrochemistry, materials science, and solid state chemistry.

Conway, B.E.; Bockris, J.O'M.; Khan, S.U.M.; White, R.E.; Yeager, E.

1983-01-01

84

Reservoir geometry and trapping mechanisms, Lindsey Slough Gas field, southern Sacramento basin  

SciTech Connect

Multiple reservoir units, numerous unconformities and stratigraphic pinch-outs, and extensive faulting make the Lindsey Slough field area (T5N, R2E, MDBM) geologically intriguing and economically attractive. The petroleum geology class of California State University, Northridge, undertook a group mapping project in November 1985, to delineate producing pools, determine reservoir geometries and trapping mechanisms, and identify potential exploration and development locations. More than 12 separate pools, producing from at least one of the 13 reservoir zones, are present. Reservoirs are of two main types: (1) extensive sheet sandstones deposited in delta-front and shelf(.) environments, and (2) lenticular channel sandstones deposited in submarine canyon, slope, and submarine fan environments. Among the sheet sandstones, the upper and lower Petersen members of the Upper Cretaceous Starkey formation are especially productive, with pay zones exceeding 100 ft. Both members pinch out to the southwest, along the paleoshelf edge. Of the lenticular sandstones, reservoir quality and thickness appear to be greatest in delta-mouth slope channels that fed sand basinward to submarine fans. Net pay in the K-1 and related upper Cretaceous channels exceeds 200 ft in some wells. Middle-fan channels of the Upper Cretaceous channels exceeds 200 ft in some wells. Middle-fan channels of the Upper Cretaceous Winters Fan are locally productive, and a small amount of gas has been produced from thin, poorly sorted sandstones within the Paleocene Martinez Submarine Canyon.

Cherven, V.; Fischer, P.; Frick, E.; Grunberg, A.; Ipswitch, S.; Menzie, R.; Pierotti, R.; Russell, P.; Schwartzbart, D.

1986-04-01

85

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

PubMed Central

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

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

2013-01-01

86

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

PubMed

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

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

2013-04-15

87

A Process Algebra Approach to Quantum Mechanics  

E-print Network

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

William H. Sulis

2014-09-07

88

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

89

Fluid mechanics mechanisms in the stall process of helicopters  

NASA Technical Reports Server (NTRS)

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.

Young, W. H., Jr.

1981-01-01

90

A Signal Processing Model of Quantum Mechanics  

E-print Network

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

Chris Thron; Johnny Watts

2012-05-08

91

Ionic motion in polypyrrole-cellulose composites: trap release mechanism during potentiostatic reduction.  

PubMed

This work investigates the movement of anions during potentiostatic controlled reduction of novel composite materials consisting of high surface area cellulose substrates, extracted from the Cladophora sp. algae, coated with thin ( approximately 50 nm) layers of the intrinsically conducting polymer (ICP) polypyrrole. The coating was achieved by chemical polymerization of pyrrole on the cellulose fibers with iron(III) chloride and phosphomolybdic acid, respectively. The composites are in the form of paper sheets and can be directly immersed into an electrolyte solution for ion absorption/desorption. The motion of glutamate and aspartate anions during cathodic polarization was investigated as a function of preceding anodic polarization at various potentials. The composite was found to exhibit memory effect as the response to a cathodic polarization of constant magnitude produced different responses depending on the magnitude of the preceding anodic potential. After the application of a cathodic potential to the composite, the reduction current curvesgenerated by anions leaving the compositewere found to initially increase in magnitude followed by a monotonic decay. A similar response has not been described and analyzed for electrochemical reduction of anion containing ICP materials earlier. A theoretical model was developed to aid the analysis of the experimental data. The model accounts for both freely mobile anions and anions that may be temporarily trapped in a contracting PPy network during cathodic polarization. By fitting the recorded reduction current curves to this model, detailed information about the ionic movement in the composite could be obtained, which may be used to further optimize the materials properties of conducting polymer systems aimed for specific electrochemical ion exchange processes. PMID:19338363

Strømme, Maria; Frenning, Göran; Razaq, Aamir; Gelin, Kristina; Nyholm, Leif; Mihranyan, Albert

2009-04-01

92

Helium induced swelling and tritium trapping mechanisms in irradiated beryllium: A comprehensive approach  

SciTech Connect

Since beryllium is considered as one of the best neutron multipliers for the blanket of a fusion reactor, several studies have been initiated to evaluate this material behavior under irradiation both for typical operating and accidental conditions. The most important effects of radiation damage in beryllium are swelling, embrittlement and tritium retention. The helium produced mainly by the reaction {sup 9}Be(n,2n)2 {sup 4}He is the dominant cause of beryllium swelling which represents the major lifetime limiting factor for the material. Furthermore, the tritium inventory in beryllium, produced by simultaneous transmutation reactions, constitutes a safety hazard in case of accidental temperature excursions in the reactor. The helium bubbles and the oxygen impurities present in the material appear to be the main causes of tritium retention in irradiated beryllium. In order to predict the performance of beryllium in the blanket up to high neutron fluences, due to the strong relation between helium bubbles distribution and tritium release, it is necessary to evaluate helium and tritium transport processes by using a comprehensive model. The kinetics and dynamics of helium and tritium in beryllium and the dynamics of the material expansion have been described by a system of coupled reaction-rate differential equations. The relevant effects occurring in irradiated beryllium under steady or transient temperature conditions have been considered from a microscopic (lattice and subgranular volume elements), structural (metallographic features of the material) and geometrical (specimen design parameters) point of view. A new model describing the trapping effects on tritium due to chemical reactions with beryllium oxide and capture in helium bubbles has been included in the code.

Scaffidi-Argentina, F.; Dalle Donne, M. [Institut fur Neutronenphysik und Reaktortechnik, Karlsruhe (Germany); Ferrero, C. [European Synchrotron Radiation Facility, Grenoble (France)] [and others

1994-12-31

93

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

SciTech Connect

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.

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

2011-05-15

94

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

Microsoft Academic Search

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

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

2008-01-01

95

A model for the trap-assisted tunneling mechanism in diffused n-p and implanted n(+)-p HgCdTe photodiodes  

NASA Technical Reports Server (NTRS)

This paper presents a theoretical model for the trap-assisted tunneling process in diffused n-on-p and implanted n(+)-on-p HgCdTe photodiodes. The model describes the connection between the leakage current associated with the traps and the trap characteristics: concentration, energy level, and capture cross sections. It is observed that the above two types of diodes differ the voltage dependence of the trap-assisted tunneling current and dynamic resistance. The model takes this difference into account and offers an explanation of the phenomenon. The good fit between measured and calculated dc characteristics of the photodiodes supports the validity of the model.

Rosenfeld, David; Bahir, Gad

1992-01-01

96

Multiple scale physical and numerical modeling for improved understanding of mechanisms of trapping and leakage of CO2 in deep geologic formations  

NASA Astrophysics Data System (ADS)

The fundamental processes associated with trapping and leakage of CO2 in deep geologic formations are complex. Formation heterogeneity manifested at all scales is expected to affect capillary and dissolution trapping and leakage of gaseous CO2 to the shallow subsurface. Research is underway to improve our fundamental understanding of trapping and leakage. This research involves experimentation in multiple scales and modeling focusing on effects of formation heterogeneity. The primary hypothesis that drives this research is that when the effects of heterogeneity on entrapment and leakage are understood, it will be possible to design more effective and safe storage schemes. Even though field investigations have some value in understanding issues related to large scale behavior and performance assessment, a fundamental understanding of how the heterogeneity affects trapping is difficult or impossible to obtain in field settings. Factors that contribute to these difficulties are the inability to fully characterize the formation heterogeneity at all scales of interest and lack of experimental control at very high depths. Intermediate scale physical model testing provides an attractive alternative to investigate these processes in the laboratory. Heterogeneities can be designed using soils with known properties in test tanks and the experiments can be conducted under controlled conditions to obtain accurate data. Conducting laboratory experiments under ambient pressure and temperature conditions to understand the processes that occur in deep formations poses many challenges. This research attempts to address such challenges and demonstrates how this testing approach could be used to generate useful data. The experiments involve the use of test systems of hierarchy of scales from small to intermediate scale tanks (~ 5 m) and long columns (~ 4.5 m). These experiments use surrogate fluids to investigate both capillary and solubility trapping in homogeneous and heterogeneous systems. A traversing x-ray scanning system is used to monitor the advancement of the plume during and after injection and to measure the residual (trapped) CO2 saturation. Dissolution of a surrogate non-wetting fluid in a surrogate wetting fluid is analyzed in small and large tanks. We test the numerical models that are capable of simulating two-phase flow and density driven flow as a result of dissolution by using the experimental data. Verified models are used to further evaluate the effect of capillary and solubility trapping in complex heterogeneous environments. During leakage, under different pressure and temperature conditions, dissolved CO2 may come back out of solution (exsolve), but the fundamental triggering mechanisms of this process in porous media are not yet well understood. An extensive series of column experiments has been conducted to investigate the factors that control the rates of CO2 gas bubble nucleation, growth, and migration. Results indicate that the saturation pressure (i.e. the amount of CO2 dissolved into the injected water) and heterogeneity both significantly affect the gas formation and migration, whereas the injection rate has less of an effect. These column experiments will soon be upscaled to an intermediate-scale two-dimensional tank to investigate the behaviour of the CO2 gas-water-soil system in more complex geological environments.

Illangasekare, T.; Plampin, M.; Trevisan, L.; Agartan, E.; Mori, H.; Sakaki, T.; Cihan, A.; Birkholzer, J.; Zhou, Q.; Pawar, R.; Zyvoloski, G.

2012-04-01

97

A Manufacturing Processes Course for Mechanical Engineers  

NSDL National Science Digital Library

Engineers need to have a working, hands-on knowledge of manufacturing processes. At California Polytechnic State University, San Luis Obispo, with few exceptions, all engineering students take freshman-level manufacturing processes courses. Mechanical Engineering students generally take three lab-oriented courses dealing with machining, foundry, and welding processes. The machining processes course, which has ten three-hour labs, introduces typical machining equipment, such as lathes, mills, and drill presses. Both hand-operated and computer controlled machines are used. Labs are limited to 20 students per section in a lab setting that contains 10 engine lathes, 5 manual/CNC vertical mills, 1 horizontal mill, 4 drill presses, 1 turretdrill press, 1 CNC lathe, and 1 CNC bed mill. Starting with measurements, students are given lab exercises that illustrate the techniques needed to manufacture a machined part. Following measuring, there is a two-week introduction to the machines, which requires individuals to operate the lathes and teams of two to operate the mills. Next, the students are given a two-week project where they individually make a screwdriver using the available equipment. The final project consists of making an air motor in teams of five, where each team is responsible for producing one-half of the parts of the air motor. During the two projects the students develop and use routing and operation sheets for each machined part.

Hoadley, Rod; Rainey, Paul

2009-07-14

98

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...

99

A Survey of Process Migration Mechanisms Jonathan M. Smith  

E-print Network

A Survey of Process Migration Mechanisms Jonathan M. Smith Computer Science Department Columbia Migration Mechanisms Jonathan M. Smith Computer Science Department Columbia University New York, NY 10027

Smith, Jonathan M.

100

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

SciTech Connect

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.

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

2007-04-15

101

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

SciTech Connect

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

Garcia, H.; Duenas, S.; Castan, H.; Gomez, A.; Bailon, L. [Departamento de Electricidad y Electronica, E.T.S.I. Telecomunicacion, Universidad de Valladolid, Campus 'Miguel Delibes', 47011 Valladolid (Spain); Toledano-Luque, M.; Prado, A. del; Martil, I.; Gonzalez-Diaz, G. [Departamento de Fisica Aplicada III (Electricidad y Electronica), Facultad de Ciencias Fisicas, Universidad Complutense, 28040 Madrid (Spain)

2008-11-01

102

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

NASA Technical Reports Server (NTRS)

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.

Rickman, D.; Gertsch, L.

2014-01-01

103

Increased biogas production at wastewater treatment plants through co-digestion of sewage sludge with grease trap sludge from a meat processing plant  

Microsoft Academic Search

The feasibility of co-digesting grease trap sludge from a meat-processing plant and sewage sludge was studied in batch and reactor experiments at 35°C. Grease trap sludge had high methane production potential (918m3\\/tVSadded), but methane production started slowly. When mixed with sewage sludge, methane production started immediately and the potential increased with increasing grease trap sludge content. Semi-continuous co-digestion of the

S. Luostarinen; S. Luste; M. Sillanpää

2009-01-01

104

Brain mechanisms for processing affective touch.  

PubMed

Despite the crucial role of touch in social development, there is very little functional magnetic resonance imaging (fMRI) research on brain mechanisms underlying social touch processing. The "skin as a social organ" hypothesis is supported by the discovery of C-tactile (CT) nerves that are present in hairy skin and project to the insular cortex. CT-fibers respond specifically well to slow, gentle touch such as that which occurs during close social interactions. Given the social significance of such touch researchers have proposed that the CT-system represents an evolutionarily conserved mechanism important for normative social development. However, it is currently unknown whether brain regions other than the insula are involved in processing CT-targeted touch. In the current fMRI study, we sought to characterize the brain regions involved in the perception of CT-supported affective touch. Twenty-two healthy adults received manual brush strokes to either the arm or palm. A direct contrast of the blood-oxygenation-level-dependent (BOLD) response to gentle brushing of the arm and palm revealed the involvement of a network of brain regions, in addition to the posterior insula, during CT-targeted affective touch to the arm. This network included areas known to be involved in social perception and social cognition, including the right posterior superior temporal sulcus and the medial prefrontal cortex (mPFC)/dorso anterior cingulate cortex (dACC). Connectivity analyses with an mPFC/dACC seed revealed coactivation with the left insula and amygdala during arm touch. These findings characterize a network of brain regions beyond the insula involved in coding CT-targeted affective touch. PMID:22125232

Gordon, Ilanit; Voos, Avery C; Bennett, Randi H; Bolling, Danielle Z; Pelphrey, Kevin A; Kaiser, Martha D

2013-04-01

105

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

106

Trapped antihydrogen  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

107

Trapped antihydrogen  

NASA Astrophysics Data System (ADS)

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

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

108

Neural mechanisms of spatiotemporal signal processing  

NASA Astrophysics Data System (ADS)

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

Khanbabaie Shoub, Shaban (Reza)

109

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

110

Thermodynamics of trapped gases: Generalized mechanical variables, equation of state, and heat capacity  

NASA Astrophysics Data System (ADS)

We present the full thermodynamics of an interacting fluid confined by an arbitrary external potential. We show that for each confining potential, there emerge “generalized” volume and pressure variables V and P , that replace the usual volume and hydrostatic pressure of a uniform system. This scheme is validated with the derivation of the virial expansion of the grand potential. We discuss how this approach yields experimentally amenable procedures to find the equation of state of the fluid, P=P(V/N,T) with N the number of atoms, as well as its heat capacity at constant generalized volume CV=CV(V,N,T) . With these two functions, all the thermodynamics properties of the system may be found. As specific examples we study weakly interacting Bose gases trapped by harmonic and by linear quadrupolar potentials within the Hartree-Fock approximation. We claim that this route provides an additional and useful tool to analyze both the thermodynamic variables of an ultracold trapped gas as well as its elementary excitations.

Sandoval-Figueroa, Nadia; Romero-Rochín, Víctor

2008-12-01

111

Thermodynamics of trapped gases: generalized mechanical variables, equation of state, and heat capacity.  

PubMed

We present the full thermodynamics of an interacting fluid confined by an arbitrary external potential. We show that for each confining potential, there emerge "generalized" volume and pressure variables V and P , that replace the usual volume and hydrostatic pressure of a uniform system. This scheme is validated with the derivation of the virial expansion of the grand potential. We discuss how this approach yields experimentally amenable procedures to find the equation of state of the fluid, P=P(VN,T) with N the number of atoms, as well as its heat capacity at constant generalized volume C_{V}=C_{V}(V,N,T) . With these two functions, all the thermodynamics properties of the system may be found. As specific examples we study weakly interacting Bose gases trapped by harmonic and by linear quadrupolar potentials within the Hartree-Fock approximation. We claim that this route provides an additional and useful tool to analyze both the thermodynamic variables of an ultracold trapped gas as well as its elementary excitations. PMID:19256824

Sandoval-Figueroa, Nadia; Romero-Rochín, Víctor

2008-12-01

112

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

E-print Network

, 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 ABSTRACT: Photovoltaic devices based on lead iodide perovskite films have seen rapid advancements, recently

Sargent, Edward H. "Ted"

113

Uncovering the mechanism of trapping and cell orientation during Neisseria gonorrhoeae twitching motility.  

PubMed

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

Zaburdaev, Vasily; Biais, Nicolas; Schmiedeberg, Michael; Eriksson, Jens; Jonsson, Ann-Beth; Sheetz, Michael P; Weitz, David A

2014-10-01

114

NREL's breakthrough process creates nanoholes that trap sunlight so that more photons can be converted into  

E-print Network

high transmission in the silver films. Any sunlight that reflects off of a solar cell is wasted a simple, low-cost way to pattern nano-sized holes in thin silver films in order to trap light waves and boost the transmission of photons into usable energy. Using a colloidal nanolithography method

115

Quantum information processing and cavity QED experiments with trapped Ca ions  

Microsoft Academic Search

Abstract Single trapped Ca, ions we realize the quantum,bit (qubit) by operating on a narrow optical S?D (quadrupole) transition. The S $ P $ D dipole transitions are driven for optical cooling, state preparation, and state detection. S1\\/2

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

2003-01-01

116

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

Microsoft Academic Search

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

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

2005-01-01

117

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

118

Mechanical-mathematical modeling for landslide process  

NASA Astrophysics Data System (ADS)

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.

Svalova, V.

2009-04-01

119

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

PubMed

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

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

2014-02-25

120

Process for predicting structural performance of mechanical systems  

DOEpatents

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.

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

1998-05-19

121

Einstein Condensation Mechanism for Low Energy Nuclear Reactions and Transmutation Processes in Condensed Matter  

E-print Network

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 6 result indicates that (d ? Li) reactions may dominate over (d+d) reactions in LENR experiments. 1.

Yeong E. Kim; Er L. Zubarev

122

On the Mechanism of Energetic Electron Losses from the Magnetic Mirror Trap at the ECR Discharge Startup  

NASA Astrophysics Data System (ADS)

In this work, we discuss experimental evidence for the existence of an effective mechanism of energetic-electron losses at the initial stage of the discharge during electron cyclotron resonance (of the ECR discharge) when the electron scattering to the loss cone is caused by the development of the electron cyclotron instabilities of a strongly nonequilibrium plasma. The spectral composition of the transient pulses of electromagnetic radiation is studied in a wide frequency range at the initial stage of the ECR discharge, when the hot-particle density exceeds that of cold particles. The observed electromagnetic-radiation bursts and synchronous energetic-electron precipitation from the trap can be related to the development of a cyclotron instability of the fast extraordinary wave in the rarefied plasma.

Viktorov, M. E.; Golubev, S. V.; Gospodchikov, E. D.; Izotov, I. V.; Mansfeld, D. A.; Shalashov, A. G.

2013-09-01

123

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...

124

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

E-print Network

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.

Véronique Gayrard; Adela Svejda

2015-01-13

125

Effect of Annealing Process on Trap Properties in High-k/Metal Gate n-Channel Metal-Oxide-Semiconductor Field-Effect Transistors through Low-Frequency Noise and Random Telegraph Noise Characterization  

NASA Astrophysics Data System (ADS)

In this research, trap properties in n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) with different annealing sequences have been studied on the basis of low-frequency (1/f) noise and random telegraph noise (RTN) analyses. The 1/f noise results indicate that the source of the drain current fluctuation is electron trapping. The higher trap density in the devices annealed before the TaN layer causes serious noise and lower trap energy in RTN results. The substitution mechanism explains that the increment of defects is due to the additional nitrogen atoms in HfO2. On the contrary, fewer defects in the devices annealed after the TaN layer are due to the effect of passivation in the TiN layer. The defect in HfO2 is the source of trapping/detrapping; thus, fewer defects cause the decrement of the fluctuation and the increment of the drain current. We believe that this process has a potential to remove defects in advanced MOSFETs.

Chiu, Hsu Feng; Lein Wu, San; Shyi Chang, Yee; Jinn Chang, Shoou; Huang, Po Chin; Chen, Jone Fang; Tsai, Shih Chang; Lai, Chien Ming; Hsu, Chia Wei; Cheng, Osbert

2013-04-01

126

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

SciTech Connect

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.

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

2010-05-15

127

Mechanism of coliphage M13 contraction: intermediate structures trapped at low temperatures.  

PubMed Central

The filamentous coliphage M13 can be transformed into a spherical particle (termed spheroid) by exposure to an interface of water and slightly polar but hydrophobic solvent such as chloroform-water at 24 degrees C. We report here that exposure of M13 filaments to a chloroform-water interface at 2 degrees C trapped the phage particles in forms morphologically intermediate to filaments and spheroids. These structures were rods 250 nm long and 15 nm wide, and each had a closed, slightly pointed end, an open flaired end, and a hollow central channel. The final contraction of these intermediates (termed I-forms) into spheroids was dependent upon both temperature and the presence of the solvent-water interface but was apparently independent of both the minor phage coat proteins and the virion DNA. Although stable in an aqueous environment, I-forms, in contrast to filaments, were readily disrupted by detergents, suggesting that the phage structure had been altered to a form more easily solubilized by membrane lipids. These solvent-induced changes might be related to the initial steps of phage penetration in vivo. Images PMID:7321105

Manning, M; Chrysogelos, S; Griffith, J

1981-01-01

128

New vanadium trap proven in commercial trials  

SciTech Connect

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.

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

1994-09-26

129

Quantitative image processing in fluid mechanics  

NASA Technical Reports Server (NTRS)

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.

Hesselink, Lambertus; Helman, James; Ning, Paul

1992-01-01

130

Efficient Collection of Single Photons Emitted from a Trapped Ion into a Single Mode Fiber for Scalable Quantum Information Processing  

NASA Astrophysics Data System (ADS)

Interference and coincidence detection of two photons emitted by two remote ions can lead to an entangled state between the ions, which is a critical resource for scalable quantum information processing [1]. The success probability of entanglement generation in current experimental realizations is mainly limited by the low coupling efficiency of a photon emitted by an ion into a single mode fiber. Here we consider two strategies to enhance the collection probability and entanglement generation rate of photons emitted from trapped Yb^+ ions. The first method uses high numerical aperture optics to enhance light collection, where a practical collection probability of over 10% is possible with proper control of aberration. The second method uses a hemispherical optical cavity created between a flat mirror containing a surface trap and a spherical mirror to enhance the spontaneous emission into the cavity mode. We show that fiber coupling efficiency of over 30% is possible using this approach, leading to an improvement in the entanglement generation rate of over four orders of magnitude. We also report on experimental progress towards realizing these two light collection schemes using surface trapped Yb^+ ions. [4pt] [1] P. Maunz et al. Phys. Rev. Lett. 102, 250502-4 (2009).

van Rynbach, Andre; Noek, Rachel; Kim, Taehyun; Maunz, Peter; Kim, Jungsang

2012-06-01

131

Mechanical-mathematical modeling for landslide process  

Microsoft Academic Search

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

V. Svalova

2009-01-01

132

Trap centers in molybdates  

NASA Astrophysics Data System (ADS)

Charge carrier trapping centers have been studied in molybdates CaMoO4, SrMoO4 and PbMoO4 with the scheelite crystal structure as well as in ZnMoO4, which crystallize in a-ZnMoO4 structural type. The trap parameters such as activation energies and frequency factors have been determined. It is shown for the first time that both electrons and holes are trapped by the elements of regular crystal structure in ZnMoO4. The effect of the charge carrier trapping on luminescence properties is demonstrated. Potential influence of the traps on the scintillation process is discussed.

Spassky, D. A.; Nagirnyi, V.; Mikhailin, V. V.; Savon, A. E.; Belsky, A. N.; Laguta, V. V.; Buryi, M.; Galashov, E. N.; Shlegel, V. N.; Voronina, I. S.; Zadneprovski, B. I.

2013-10-01

133

The floating oil pool - A unique trapping mechanism at Kern River field  

Microsoft Academic Search

Geologic reevaluation of the giant Kern River field, a 4 billion bbl oil accumulation, suggests a nontrapping oil emplacement mechanism not previously described in the literature. The field produces 12-14° API oil from a shallow, thick sequence of stacked fluvial sands situated across a homocline that dips 4-5° southwest. Migration of hydrocarbons generated in deeply buried Miocene shales ended in

E. J. Kodl; J. C. Eacman

1990-01-01

134

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

Code of Federal Regulations, 2013 CFR

...Mechanized claims processing and information retrieval systems; definitions...Mechanized claims processing and information retrieval systems; definitions...mechanized claims processing and information retrieval system, hereafter...

2013-10-01

135

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

...Mechanized claims processing and information retrieval systems; definitions...Mechanized claims processing and information retrieval systems; definitions...mechanized claims processing and information retrieval system, hereafter...

2014-10-01

136

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

Code of Federal Regulations, 2012 CFR

...Mechanized claims processing and information retrieval systems; definitions...Mechanized claims processing and information retrieval systems; definitions...mechanized claims processing and information retrieval system, hereafter...

2012-10-01

137

Molecular basis of TRAP-5'SL RNA interaction in the Bacillus subtilis trp operon transcription attenuation mechanism.  

PubMed

Expression of the Bacillus subtilis trpEDCFBA operon is regulated by the interaction of tryptophan-activated TRAP with 11 (G/U)AG trinucleotide repeats that lie in the leader region of the nascent trp transcript. Bound TRAP prevents folding of an antiterminator structure and favors formation of an overlapping intrinsic terminator hairpin upstream of the trp operon structural genes. A 5'-stem-loop (5'SL) structure that forms just upstream of the triplet repeat region increases the affinity of TRAP-trp RNA interaction, thereby increasing the efficiency of transcription termination. Single-stranded nucleotides in the internal loop and in the hairpin loop of the 5'SL are important for TRAP binding. We show here that altering the distance between these two loops suggests that G7, A8, and A9 from the internal loop and A19 and G20 from the hairpin loop constitute two structurally discrete TRAP-binding regions. Photochemical cross-linking experiments also show that the hairpin loop of the 5'SL is in close proximity to the flexible loop region of TRAP during TRAP-5'SL interaction. The dimensions of B. subtilis TRAP and of a three-dimensional model of the 5'SL generated using the MC-Sym and MC-Fold pipeline imply that the 5'SL binds the protein in an orientation where the helical axis of the 5'SL is perpendicular to the plane of TRAP. This interaction not only increases the affinity of TRAP-trp leader RNA interaction, but also orients the downstream triplet repeats for interaction with the 11 KKR motifs that lie on TRAP's perimeter, increasing the likelihood that TRAP will bind in time to promote termination. PMID:19033375

McGraw, Adam P; Mokdad, Ali; Major, François; Bevilacqua, Philip C; Babitzke, Paul

2009-01-01

138

Reactive atomization and deposition process: Fundamental mechanisms  

NASA Astrophysics Data System (ADS)

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

Lin, Yaojun

139

Interfacial fluid mechanics and transport processes  

SciTech Connect

Macroscale interfacial conservation and constitutive equations, as well as expressions for the phenomenological functions appearing in the report, are derived for transport processes occurring in immiscible fluid-fluid systems possessing moving and deforming interfaces via a rigorous matched asymptotic expansion scheme from the more exact, continuous ('diffuse') microscale equations underlying them. 10 refs., 2 figs.

Mavrovouniotis, G.M.; Brenner, H.; Ting, L.; Wasan, D.T.

1989-01-01

140

Mechanics Review ME 6222: Manufacturing Processes and  

E-print Network

)Linear elastic (simplest) ­ Young's modulus, E = /e E Thomas Young 1773-1829 1 1773 1829 e Robert Hooke ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009 7 Robert Hooke 1635-1703 #12;Actual Material

Colton, Jonathan S.

141

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)

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.

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

2014-10-01

142

Integrating Thermal Tools Into the Mechanical Design Process  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

143

Blandford-Znajek mechanism versus Penrose process  

E-print Network

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.

S. S. Komissarov

2008-04-11

144

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

NASA Astrophysics Data System (ADS)

The stable operation of transistors under a positive bias stress (PBS) is achieved using Hf incorporated into InOx-based thin films processed at relatively low temperatures (150 to 250 °C). The mobilities of the Hf-InOx thin-film transistors (TFTs) are higher than 8 cm2/Vs. The TFTs not only have negligible degradation in the mobility and a small shift in the threshold voltage under PBS for 60 h, but they are also thermally stable at 85 °C in air, without the need for a passivation layer. The Hf-InOx TFT can be stable even annealed at 150 °C for positive bias temperature stability (PBTS). A higher stability is achieved by annealing the TFTs at 250 °C, originating from a reduction in the trap density at the Hf-InOx/gate insulator interface. The knowledge obtained here will aid in the realization of stable TFTs processed at low temperatures.

Lin, Meng-Fang; Gao, Xu; Mitoma, Nobuhiko; Kizu, Takio; Ou-Yang, Wei; Aikawa, Shinya; Nabatame, Toshihide; Tsukagoshi, Kazuhito

2015-01-01

145

Respiratory fluid mechanics and transport processes.  

PubMed

The field of respiratory flow and transport has experienced significant research activity over the past several years. Important contributions to the knowledge base come from pulmonary and critical care medicine, surgery, physiology, environmental health sciences, biophysics, and engineering. Several disciplines within engineering have strong and historical ties to respiration including mechanical, chemical, civil/environmental, aerospace and, of course, biomedical engineering. This review draws from a wide variety of scientific literature that reflects the diverse constituency and audience that respiratory science has developed. The subject areas covered include nasal flow and transport, airway gas flow, alternative modes of ventilation, nonrespiratory gas transport, aerosol transport, airway stability, mucus transport, pulmonary acoustics, surfactant dynamics and delivery, and pleural liquid flow. Within each area are a number of subtopics whose exploration can provide the opportunity of both depth and breadth for the interested reader. PMID:11447070

Grotberg, J B

2001-01-01

146

A fly trap mechanism provides sequence-specific RNA recognition by CPEB proteins  

PubMed Central

Cytoplasmic changes in polyA tail length is a key mechanism of translational control and is implicated in germline development, synaptic plasticity, cellular proliferation, senescence, and cancer progression. The presence of a U-rich cytoplasmic polyadenylation element (CPE) in the 3? untranslated regions (UTRs) of the responding mRNAs gives them the selectivity to be regulated by the CPE-binding (CPEB) family of proteins, which recognizes RNA via the tandem RNA recognition motifs (RRMs). Here we report the solution structures of the tandem RRMs of two human paralogs (CPEB1 and CPEB4) in their free and RNA-bound states. The structures reveal an unprecedented arrangement of RRMs in the free state that undergo an original closure motion upon RNA binding that ensures high fidelity. Structural and functional characterization of the ZZ domain (zinc-binding domain) of CPEB1 suggests a role in both protein–protein and protein–RNA interactions. Together with functional studies, the structures reveal how RNA binding by CPEB proteins leads to an optimal positioning of the N-terminal and ZZ domains at the 3? UTR, which favors the nucleation of the functional ribonucleoprotein complexes for translation regulation. PMID:24990967

Afroz, Tariq; Skrisovska, Lenka; Belloc, Eulàlia; Guillén-Boixet, Jordina; Méndez, Raúl; Allain, Frédéric H.-T.

2014-01-01

147

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

NASA Astrophysics Data System (ADS)

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

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

2007-09-01

148

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

E-print Network

with a discharge time of about 100 s. These mechanisms are exceedingly fast, but take place only once because plant tissues are torn during the process. On the other hand, fast and repetitive movements in plants are often carnivorous plants Dionaea muscipula and Aldrovanda vesiculosa Simon Poppinga1 and Marc Joyeux2,* 1 Plant

149

Formation process and mechanical property of slickenside  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

150

Ultra-fast underwater suction traps  

PubMed Central

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

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

2011-01-01

151

Structural Changes in Isometrically Contracting Insect Flight Muscle Trapped following a Mechanical Perturbation  

PubMed Central

The application of rapidly applied length steps to actively contracting muscle is a classic method for synchronizing the response of myosin cross-bridges so that the average response of the ensemble can be measured. Alternatively, electron tomography (ET) is a technique that can report the structure of the individual members of the ensemble. We probed the structure of active myosin motors (cross-bridges) by applying 0.5% changes in length (either a stretch or a release) within 2 ms to isometrically contracting insect flight muscle (IFM) fibers followed after 5–6 ms by rapid freezing against a liquid helium cooled copper mirror. ET of freeze-substituted fibers, embedded and thin-sectioned, provides 3-D cross-bridge images, sorted by multivariate data analysis into ?40 classes, distinct in average structure, population size and lattice distribution. Individual actin subunits are resolved facilitating quasi-atomic modeling of each class average to determine its binding strength (weak or strong) to actin. ?98% of strong-binding acto-myosin attachments present after a length perturbation are confined to “target zones” of only two actin subunits located exactly midway between successive troponin complexes along each long-pitch helical repeat of actin. Significant changes in the types, distribution and structure of actin-myosin attachments occurred in a manner consistent with the mechanical transients. Most dramatic is near disappearance, after either length perturbation, of a class of weak-binding cross-bridges, attached within the target zone, that are highly likely to be precursors of strong-binding cross-bridges. These weak-binding cross-bridges were originally observed in isometrically contracting IFM. Their disappearance following a quick stretch or release can be explained by a recent kinetic model for muscle contraction, as behaviour consistent with their identification as precursors of strong-binding cross-bridges. The results provide a detailed model for contraction in IFM that may be applicable to contraction in other types of muscle. PMID:22761792

Wu, Shenping; Liu, Jun; Perz-Edwards, Robert J.; Tregear, Richard T.; Winkler, Hanspeter; Franzini-Armstrong, Clara; Sasaki, Hiroyuki; Goldman, Yale E.; Reedy, Michael K.; Taylor, Kenneth A.

2012-01-01

152

IntroductiontoProcessEngineering(PTG) 6. Fluid mechanics  

E-print Network

#6/6 IntroductiontoProcessEngineering(PTG) VST rz13 1/96 6. Fluid mechanics: fluid statics; fluid") Introduction to Process Engineering v.2013 #6/6 IntroductiontoProcessEngineering(PTG) VST rz13 2/96 6.1 Fluid statics #12;#6/6 IntroductiontoProcessEngineering(PTG) VST rz13 3/96 Fluid statics, static pressure /1

Zevenhoven, Ron

153

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

NASA Astrophysics Data System (ADS)

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.

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

2003-11-01

154

Mechanisms That Interchange Axial and Equatorial Atoms in Fluxional Processes  

NSDL National Science Digital Library

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

155

Two-qubit decoherence mechanisms revealed via quantum process tomography  

SciTech Connect

We analyze the quantum process tomography (QPT) in the presence of decoherence, focusing on distinguishing local and nonlocal decoherence mechanisms for a two-partite system from experimental QPT data. In particular, we consider the {radical}(iSWAP) gate realized with superconducting phase qubits and calculate the QPT matrix {chi} in the presence of several local and nonlocal decoherence processes. We determine specific patterns of these decoherence processes, which can be used for a fast identification of the main decoherence mechanisms from an experimental {chi} matrix.

Kofman, A. G.; Korotkov, A. N. [Department of Electrical Engineering, University of California, Riverside, California 92521 (United States)

2009-10-15

156

Lysosomal trapping of a radiolabeled substrate of P-glycoprotein as a mechanism for signal amplification in PET  

PubMed Central

The radiotracer [11C]N-desmethyl-loperamide (dLop) images the in vivo function of P-glycoprotein (P-gp), a transporter that blocks the entry of drugs that are substrates into brain. When P-gp is inhibited, [11C]dLop, a potent opiate agonist, enters and becomes trapped in the brain. This trapping is beneficial from an imaging perspective, because it amplifies the PET signal, essentially by accumulating radioactivity over time. As we previously demonstrated that this trapping was not caused by binding to opiate receptors, we examined whether [11C]dLop, a weak base, is ionically trapped in acidic lysosomes. To test this hypothesis, we measured [3H]dLop accumulation in human cells by using lysosomotropics. Because the in vivo trapping of dLop was seen after P-gp inhibition, we also measured [3H]dLop uptake in P-gp–expressing cells treated with the P-gp inhibitor tariquidar. All lysosomotropics decreased [3H]dLop accumulation by at least 50%. In P-gp–expressing cells, tariquidar (and another P-gp inhibitor) surprisingly decreased [3H]dLop uptake. Consequently, we measured [11C]dLop uptake before and after tariquidar preadministration in lysosome-rich organs of P-gp KO mice and humans. After tariquidar pretreatment in both species, radioactivity uptake in these organs decreased by 35% to 40%. Our results indicate that dLop is trapped in lysosomes and that tariquidar competes with dLop for lysosomal accumulation in vitro and in vivo. Although tariquidar and dLop compete for lysosomal trapping in the periphery, such competition does not occur in brain because tariquidar has negligible entry into brain. In summary, tariquidar and [11C]dLop can be used in combination to selectively measure the function of P-gp at the blood–brain barrier. PMID:21262843

Kannan, Pavitra; Brimacombe, Kyle R.; Kreisl, William C.; Liow, Jeih-San; Zoghbi, Sami S.; Telu, Sanjay; Zhang, Yi; Pike, Victor W.; Halldin, Christer; Gottesman, Michael M.; Innis, Robert B.; Hall, Matthew D.

2011-01-01

157

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

158

Mechanical pre-treatment (MPT) - revitalised by MBR process.  

PubMed

Since the mid-nineties membrane bioreactor (MBR) technology has been introduced to municipal wastewater treatment in Europe. The first MBR plants went into operation performing a conventional mechanical pre-treatment (MPT) without any advanced treatment units. After a short operation period, clogging caused by fibrous substances and hence module sludging was observed. Thus, MPT was upgraded introducing sieves. Several investigations had been carried out to determine the removal efficiency of different sieve units and entire MPT systems. Meanwhile experiences from long-term operation at different MBR sites indicate dependencies between different MPT units, especially between the aerated grit chamber/grease trap and the subsequent sieve unit. Usually the sieve is the final MPT unit and its performance depends on the performance of the upstream MPT units. This report describes and discusses results from a research project at MBR Kaarst-Nordkanal in Germany conducted in 2008 to 2010 by the Water Board of River Erft and the Department of Sanitary and Environmental Engineering. Main focus is addressed for the parameters SS (settable solids) and grease. One major experience is the confirmation of relevant interactions between the grit chamber and the downstream sieve unit. Stable operation of the grit chamber and grease trap is essential to achieve a constantly high removal performance of the sieve unit and therefore the entire MPT stage. In turn, negative impacts on the grit chamber performance from the return flow concept have to be avoided. Finally, it is shown that the appropriate two-dimensional sieve gap size should not go beyond 1 mm when operating hollow fibre membranes. PMID:23109566

Schier, W; Drensla, K; Janot, A; Exler, H; Engelhardt, N; Frechen, F-B

2012-01-01

159

Magnetic Trapping - Trapped Radiation  

NSDL National Science Digital Library

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

Stern, David

2005-04-27

160

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

Code of Federal Regulations, 2013 CFR

...Applicability; description of the mechanized clam processing subcategory. 408.240 ...PROCESSING POINT SOURCE CATEGORY Mechanized Clam Processing Subcategory § 408.240 Applicability; description of the mechanized clam processing subcategory. The...

2013-07-01

161

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

Code of Federal Regulations, 2010 CFR

...Applicability; description of the mechanized clam processing subcategory. 408.240 ...PROCESSING POINT SOURCE CATEGORY Mechanized Clam Processing Subcategory § 408.240 Applicability; description of the mechanized clam processing subcategory. The...

2010-07-01

162

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

Code of Federal Regulations, 2011 CFR

...Applicability; description of the mechanized clam processing subcategory. 408.240 ...PROCESSING POINT SOURCE CATEGORY Mechanized Clam Processing Subcategory § 408.240 Applicability; description of the mechanized clam processing subcategory. The...

2011-07-01

163

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

...Applicability; description of the mechanized clam processing subcategory. 408.240 ...PROCESSING POINT SOURCE CATEGORY Mechanized Clam Processing Subcategory § 408.240 Applicability; description of the mechanized clam processing subcategory. The...

2014-07-01

164

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

Code of Federal Regulations, 2012 CFR

...Applicability; description of the mechanized clam processing subcategory. 408.240 ...PROCESSING POINT SOURCE CATEGORY Mechanized Clam Processing Subcategory § 408.240 Applicability; description of the mechanized clam processing subcategory. The...

2012-07-01

165

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

166

CONTINUOUS vs DISCRETE PROCESSES: THE PROBABILISTIC EVOLUTION OF SINGLE TRAPPED IONS.  

E-print Network

, as a Markov process. The latter models the atom as making instantaneous transitions from one energy eigenstate discussion between Bohr, Heisenberg and Schrödinger. 2. Rate equations for atomic change of state. The three and dark periods. 2. Rate equations for atomic change of state. 3. Discrete, non-continuous atomic

George, Glyn

167

Process-induced trapping of charge in PECVD dielectrics for RF MEMS capacitive switches  

Microsoft Academic Search

Charge-induced failure is recognized as the primary reliability issue in RF MEMS capacitive switches. In this paper, we present a simplified method for quantifying the effects of process-induced charging of plasma-enhanced, chemical vapor deposition (PECVD) dielectrics commonly used in the fabrication of these devices. Using this method, based on capacitance-voltage (C-V) measurements of MIS (metal-insulator-semiconductor) devices, we examined the charge

J. R. Webster; C. W. Dyck; C. D. Nordquist; J. A. Felix; M. R. Shaneyfeft; J. R. Schwank; J. C. Banks

2005-01-01

168

Protein-based bioplastics: effect of thermo-mechanical processing  

Microsoft Academic Search

Bioplastics based on glycerol and different proteins (wheat gluten, albumen, rice and albumen\\/gluten blends) have been manufactured\\u000a to determine the effect that processing and further thermal treatments exert on different thermo-mechanical properties of\\u000a the bioplastics obtained. Oscillatory shear, modulated differential scanning calorimetry, dynamic mechanical thermal analysis,\\u000a thermo-gravimetric analysis and water absorption tests were carried out to study the effect of

Abel Jerez; Pedro Partal; Inmaculada Martínez; Críspulo Gallegos; Antonio Guerrero

2007-01-01

169

Venus fly trap  

NSDL National Science Digital Library

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

Paul Lenz (None;)

2006-01-26

170

Mechanics of aeolian processes: Soil erosion and dust production  

NASA Technical Reports Server (NTRS)

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.

Mehrabadi, M. M.

1989-01-01

171

Social Information Processing Mechanisms and Victimization: A Literature Review.  

PubMed

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

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

2014-11-10

172

Mechanical integrity implementation and related process safety management elements  

SciTech Connect

The OSHA Process Safety Management (PSM) rule requires covered facilities to establish a mechanical integrity (MI) program. The MI program must address an ongoing effort to maintain the integrity of process equipment and safety systems by providing written procedures, training, inspection and testing, and quality assurance. Development of an MI program requires information from other PSM elements such as equipment process safety information and employee participation as building blocks for the program. Information obtained from other elements of PSM can be used as the basis for inspection and testing, frequency of testing, written maintenance procedures, training of maintenance personnel, and quality assurance of spare parts and newly installed equipment. This paper presents highlights in the implementation of a mechanical integrity program. A description of the use of process safety information and baseline inspections is detailed with appropriate examples. The MI program stems from an initial documentation review, and culminates in a completely functional MI program in compliance with the regulation.

Hudson, K.M. [General Physics Corp., San Diego, CA (United States)

1995-12-31

173

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

NASA Astrophysics Data System (ADS)

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.

Stein, David

174

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

PubMed

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

Brownlee, Colin

2013-09-01

175

Production of thermoelectric materials by mechanical alloying extrusion process  

Microsoft Academic Search

The extrusion process offers one of the greatest prospects for the industrial production of Bi2Te3-based thermoelectric alloys. When coupled with mechanical alloying, this process promises substantial cost savings because of its ability to deliver net shape components, leading to a reduction in the so-called kerf losses and higher material yields. It is also well known that materials produced using one

J.-M. Simard; D. Vasilevskiy; F. Belanger; J. L'Ecuyer; S. Turenne

2001-01-01

176

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

Code of Federal Regulations, 2010 CFR

...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...

2010-07-01

177

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

...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...

2014-07-01

178

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

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

179

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

...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...

2014-07-01

180

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

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

181

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

Code of Federal Regulations, 2011 CFR

...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...

2011-07-01

182

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

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

183

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

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

184

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

Code of Federal Regulations, 2011 CFR

...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...

2011-07-01

185

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

...mechanized claims processing and information retrieval systems. 433.116 Section...Mechanized Claims Processing and Information Retrieval Systems § 433.116 ...mechanized claims processing and information retrieval systems. (a)...

2014-10-01

186

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

Code of Federal Regulations, 2012 CFR

...mechanized claims processing and information retrieval systems. 433.116 Section...Mechanized Claims Processing and Information Retrieval Systems § 433.116 ...mechanized claims processing and information retrieval systems. (a)...

2012-10-01

187

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

Code of Federal Regulations, 2013 CFR

...mechanized claims processing and information retrieval systems. 433.116 Section...Mechanized Claims Processing and Information Retrieval Systems § 433.116 ...mechanized claims processing and information retrieval systems. (a)...

2013-10-01

188

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

Code of Federal Regulations, 2011 CFR

...mechanized claims processing and information retrieval systems. 433.116 Section...Mechanized Claims Processing and Information Retrieval Systems § 433.116 ...mechanized claims processing and information retrieval systems. (a)...

2011-10-01

189

Charge trapping and detrapping in polymeric materials: Trapping parameters  

NASA Astrophysics Data System (ADS)

Space charge formation in polymeric materials can cause some serious concern for design engineers as the electric field may severely be distorted, leading to part of the material being overstressed. This may result in material degradation and possibly premature failure at the worst. It is therefore important to understand charge generation, trapping, and detrapping processes in the material. Trap depths and density of trapping states in materials are important as they are potentially related to microstructure of the material. Changes in these parameters may reflect the aging taken place in the material. In the present paper, characteristics of charge trapping and detrapping in low density polyethylene (LDPE) under dc electric field have been investigated using the pulsed electroacoustic (PEA) technique. A simple trapping and detrapping model based on two trapping levels has been used to qualitatively explain the observation. Numerical simulation based on the above model has been carried out to extract parameters related to trapping characteristics in the material. It has been found that the space charge decaying during the first few hundred seconds corresponding to the fast changing part of the slope was trapped with the shallow trap depth 0.88 eV, with trap density 1.47 × 1020 m-3 in the sample volume measured. At the same time, the space charge that decays at longer time corresponding to the slower part of the slope was trapped with the deep trap depth 1.01 eV, with its trap density 3.54 × 1018 m-3. The results also indicate that trap depths and density of both shallow and deep traps may be used as aging markers as changes in the material will certainly affect trapping characteristics in terms of trap depth and density.

Zhou, Tian-chun; Chen, George; Liao, Rui-jin; Xu, Zhiqiang

2011-08-01

190

Characterization of Random Telegraph Noise Generated by Process- and Cycling-Stress-Induced Traps in 26 nm NAND Flash Memory  

NASA Astrophysics Data System (ADS)

We characterized normalized noise power density (SI/IBL2) and bit-line (BL) current fluctuation (?IBL) using traps generated applying cycling stress in 26 nm NAND flash memory. The ?IBL, SI/IBL2, and capture (?c) and emission times (?e) of random telegraph noise (RTN) were measured before and after cycling stress, respectively. With cycling stress, traps were generated, and SI/IBL2 and ?IBL were increased significantly. The ?c and ?e of RTN after cycling stress are similar with to those before cycling stress. RTN was characterized in terms of the trap position in the three-dimensional space (xT, yT, and zT) of the tunneling oxide and trap energy (ET). three-dimensional technology computer-aided design (TCAD) simulation was used to determine the position of zT through the effect of adjacent BL cells.

Jo, Bong-Su; Kang, Ho-Jung; Joe, Sung-Min; Jeong, Min-Kyu; Han, Kyung-Rok; Park, Sung-Kye; Park, Byung-Gook; Lee, Jong-Ho

2013-04-01

191

Early Olfactory Processing in Drosophila: Mechanisms and Principles  

PubMed Central

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

Wilson, Rachel I.

2014-01-01

192

An improved numerical process for solution of solid mechanics problems  

NASA Technical Reports Server (NTRS)

This paper gives an overview of the development and status of an improved numerical process for the solution of solid mechanics problems. The proposed process uses a mixed formulation with the fundamental unknowns consisting of both stress and displacement parameters. The problem is formulated either by means of first-order partial differential equations or in a variational form by using a Hellinger-Reissner-type mixed variational principle. For presentation purposes, the components of a numerical process are characterized and the criteria for an ideal process are outlined. Commonly used finite-difference and finite-element procedures are examined in the light of these criteria and it is shown that they fall short in a number of ways. The proposed numerical process, on the other hand, satisfies most of the optimality criteria and appears to be particularly suited for use with the forthcoming generation computers.

Noor, A. K.; Stephens, W. B.; Fulton, R. E.

1973-01-01

193

Trapping Coyotes  

E-print Network

establish regular travel routes along livestock trails, ranch roads, canyons, ridges or any path that offers easy travel and good visibili- ty.Atrappercanfindthesetravelroutesbylook- ing for coyote sign, tracks and droppings. Coyote tracks are similar to dog... trapping non- target animals such as opossums, raccoons, skunks, badgers, etc., under-pan springs can be usedtoincreasetheamountofpressurerequired to throw the trap. The under-pan spring fits on the base of the trap and provides tension...

Texas Wildlife Services

2008-04-15

194

Optical trapping  

SciTech Connect

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

Neuman, Keir C.; Block, Steven M. [Department of Biological Sciences, and Department of Applied Physics, Stanford University, Stanford, California 94305 (United States)

2004-09-01

195

Hybrid Mechanical Systems  

E-print Network

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

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

2015-01-06

196

Magnetic Penrose Process and Blanford-Zanejk mechanism: A clarification  

E-print Network

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...

Dadhich, Naresh

2012-01-01

197

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

NASA Technical Reports Server (NTRS)

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.

Iskenderian, Ted

2004-01-01

198

A proposal for mitochondrial processing peptidase catalytic mechanism.  

PubMed

The reaction mechanism of the Mitochondrial Processing Peptidase enzyme (MPP) was investigated by using hybrid density functional theory. This enzyme removes the NH(2)-terminal targeting signals of nuclear-encoded mitochondrial protein precursors in the mitochondrial matrix. The catalytic process was studied using a model for the active site consisting of 161 atoms locating all the stationary points on the potential energy curve and determining the main energetic, structural, and electronic features that drive the catalysis. Despite the differences between the B3LYP and MPWB1K descriptions, it is possible hypothesize that the rate-limiting step of the reaction is most likely the nucleophilic attack of zinc-bound hydroxide to a carbonyl carbon of the substrate. The results allowed assignment of the proper roles to some active site residues in this mechanism. PMID:21988451

Amata, Orazio; Marino, Tiziana; Russo, Nino; Toscano, Marirosa

2011-11-01

199

Active Cellular Mechanics and Information Processing in the Living Cell  

NASA Astrophysics Data System (ADS)

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.

Rao, M.

2014-07-01

200

The interplay between cell signaling and mechanics in developmental processes  

PubMed Central

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

Miller, Callie Johnson; Davidson, Lance

2014-01-01

201

Quantum mechanical model for two-state jump Markovian process  

Microsoft Academic Search

A quantum mechanical model is given which is equivalent to the stochastic dephasing subject to the two-state jump Markovian process. The stochastic variable corresponds to a Hermitian operator of a spin-1\\/2 system which is embedded in a thermal reservoir, where the time-evolution of the spin-1\\/2 system is described by the quantum master equation of the Lindblad form.

Masashi Ban; Sachiko Kitajima; Kishiko Maruyama; Fumiaki Shibata

2008-01-01

202

Magneto-optical Trapping of Cadmium  

E-print Network

We report the laser-cooling and confinement of Cd atoms in a magneto-optical trap, and characterize the loading process from the background Cd vapor. The trapping laser drives the 1S0-1P1 transition at 229 nm in this two-electron atom and also photoionizes atoms directly from the 1P1 state. This photoionization overwhelms the other loss mechanisms and allows a direct measurement of the photoionization cross section, which we measure to be 2(1)x10^(-16)cm^(2) from the 1P1 state. When combined with nearby laser-cooled and trapped Cd^(+) ions, this apparatus could facilitate studies in ultracold interactions between atoms and ions.

Brickman, K -A; Acton, M; Chew, A; Matsukevich, D; Haljan, P C; Bagnato, V S; Monroe, C

2007-01-01

203

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

NASA Astrophysics Data System (ADS)

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.

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

2011-05-01

204

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

NASA Astrophysics Data System (ADS)

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

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

2004-10-01

205

Transport mechanism and trap distribution in ITO/azo-calix[4]arene derivative/Al diode structure  

NASA Astrophysics Data System (ADS)

Electrical measurements have been performed on spin-coated azo-calix[4]arene derivative on pre-cleaned indium thin oxide (ITO) substrates using current versus voltage, capacitance versus voltage and impedance spectroscopy measurements. The nature of trap states in single layer ITO/azo-calix[4]arene derivative/Al organic diodes has also been investigated. The energy band gap of the thin film containing calixarene derivative has been measured by UV-Vis absorption spectroscopy and is about 2.77 eV. The current-voltage characteristics have shown ohmic behavior at low voltages. At high applied bias the I-V characteristics can be successfully modeled by space-charge limited current (SCLC) theory. The impedance dependence of bias and frequency is discussed in terms of the presence of a depletion layer in the bulk. The device is accurately modeled, in a range of frequency between 100 Hz and 1 MHz, as a single parallel resistor and capacitor network placed in series with a resistance. Their values deduced from fitting experimental data to the model have given a dielectric relaxation time in the ms range and an exponential trap distribution.

Rouis, A.; Dridi, C.; Dumazet-Bonnamour, I.; Davenas, J.; Ben Ouada, H.

2007-11-01

206

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

PubMed Central

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

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

2014-01-01

207

Mechanical and tribological properties of ion beam-processed surfaces  

SciTech Connect

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.

Kodali, P.

1998-01-01

208

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

Microsoft Academic Search

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

Joseph Weiss

1960-01-01

209

Rb\\/Sr-Sr\\/Sr Variations in Bombay Trachytes and Rhyolites (Deccan Traps): Rb-Sr Isochron, or AFC Process?  

Microsoft Academic Search

A petrologically diverse suite of Deccan Trap rocks, comprising basalts, trachytes, rhyolites, and various alkaline rocks, was studied in the Bombay area along the western Indian rifted continental margin. A previous petrogenetic study of these trachytes and rhyolites suggested derivation through fractional crystallization of basaltic magmas, or partial melting of basaltic material at depth, without involvement of continental crust. A

Hetu C. Sheth; Jyotiranjan S. Ray

2002-01-01

210

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

E-print Network

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.

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

2014-06-11

211

Mechanisms of Carbon Nanotube Production by Laser Ablation Process  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

212

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

SciTech Connect

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

Zeng Xiancheng; Hu Hao; Hu Xiangqian; Cohen, Aron J.; Yang Weitao [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States)

2008-03-28

213

Entanglement of Trapped Ions  

Microsoft Academic Search

Entanglement, its generation, manipulation, measurement and fundamental understanding is at the very heart of quantum mechanics. We here report on the creation and characterization of entangled states of up to 8 trapped ions, the investigation of long-lived two-ion Bell-states and on experiments towards entangling ions and photons.

C. Becher; J. Benhelm; D. Chek-Al-Kar; M. Chwalla; W. Dür; O. Gühne; H. Häffner; W. Hänsel; T. Körber; A. Kreuter; G. P. T. Lancaster; T. Monz; E. S. Phillips; U. D. Rapol; M. Riebe; C. F. Roos; C. Russo; F. Schmidt-Kaler; R. Blatt

2005-01-01

214

Magnetic Penrose Process and Blanford-Zanejk mechanism: A clarification  

E-print Network

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 which the rotational energy of the hole is extracted out through a purely electromagnetic process. Though both the processes use magnetic field as a device to extract rotational energy from the hole, yet their kernel is quite different in spirit. For the former magnetic field provides the threshold energy for particle to get onto negative energy orbit so that the other fragment goes out with enhanced energy while for the latter it generates an electric potential difference between the equatorial plane and the polar region, and it is the discharge of which that drives the energy flux out of the hole. In other words, MPP is still rooted in the spacetime geometry while BZ is essentially driven by electromagnetic interaction.

Naresh Dadhich

2012-10-03

215

Discrimination of crude and processed rhubarb products using a chemometric approach based on ultra fast liquid chromatography with ion trap/time-of-flight mass spectrometry.  

PubMed

Crude rhubarb subjected to different processing procedures will produce different therapeutic effects that are possibly due to processing-induced variation in chemical composition. In this study, a chemometric approach based on ultra fast liquid chromatography with ion trap/time-of-flight mass spectrometry was established to systematically investigate the chemical variations of rhubarb induced by different processing methods. The approach was validated based on pooled quality-control samples from two perspectives: the individual properties of variables and the bulk properties of samples. Orthogonal partial least squares discriminant analysis was introduced to compare the differences between crude and processed rhubarb products. A total of 20 significantly different markers were screened out and unambiguously/tentatively characterized. This research proved that a chemometric method based on ultra fast liquid chromatography with ion trap/time-of-flight mass spectrometry can comprehensively analyze the chemical variation of herbal medicine and provide evidence for a deeper understanding of the pharmacological activities of processed rhubarb products. PMID:25421806

Wang, Min; Fu, Jinfeng; Guo, Huimin; Tian, Yuan; Xu, Fengguo; Song, Rui; Zhang, Zunjian

2015-02-01

216

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

217

Evolution of attention mechanisms for early visual processing  

NASA Astrophysics Data System (ADS)

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.

Müller, Thomas; Knoll, Alois

2011-03-01

218

Development of brain mechanisms for processing affective touch  

PubMed Central

Affective tactile stimulation plays a key role in the maturation of neural circuits, but the development of brain mechanisms processing touch is poorly understood. We therefore used functional magnetic resonance imaging (fMRI) to study brain responses to soft brush stroking of both glabrous (palm) and hairy (forearm) skin in healthy children (5–13 years), adolescents (14–17 years), and adults (25–35 years). Adult-defined regions-of-interests in the primary somatosensory cortex (SI), secondary somatosensory cortex (SII), insular cortex and right posterior superior temporal sulcus (pSTS) were significantly and similarly activated in all age groups. Whole-brain analyses revealed that responses in the ipsilateral SII were positively correlated with age in both genders, and that responses in bilateral regions near the pSTS correlated significantly and strongly with age in females but not in males. These results suggest that brain mechanisms associated with both sensory-discriminative and affective-motivational aspects of touch are largely established in school-aged children, and that there is a general continuing maturation of SII and a female-specific increase in pSTS sensitivity with age. Our work establishes a groundwork for future comparative studies of tactile processing in developmental disorders characterized by disrupted social perception such as autism. PMID:24550800

Björnsdotter, Malin; Gordon, Ilanit; Pelphrey, Kevin A.; Olausson, Håkan; Kaiser, Martha D.

2014-01-01

219

Nonlinear fracture mechanics formability criterion for plastic deformation processes  

SciTech Connect

This work presents a model and an experimental procedure for building up the formability maps for metal forming based on nonlinear fracture mechanics. Formability is the limiting condition from which superficial or internal fractures propagate inside the plastic region in metal forming by compressive manufacturing process. The formability criterion developed in this paper through the Noether`s generalized invariant integral theorem is the best way to deal with near ductile metal in the, manufacturing processes. Model analysis will lead to the construction of the formability maps. It will show the limitation of plasticity theory for the analysis of the compressive type metal forming operations near a fracture region. It may put an upper boundary on the construction of an easy applicable formability criterion on practical problems from a day to day basis. This work establishes an experimental method based on the Noether`s invariant theorem, the HRR model for stress distribution near the crack tip in the deformed region, and Hill`s plasticity theorem. It results in an experimental method of low cost, and easy implementation for any single industrial laboratory. The mentioned procedure is applied to the analysis of a flat open die cold forging of a precipitation hardened UNS A92024 Al-Cu alloy. This will allow the construction of a formability model based on experimental results. The model to be discussed would lead to the generalization of a formability criterion in metal forming studies that would relate to on many practical problems. The authors carry out a review of the literature on nonlinear fracture mechanics, the conservation laws in finite elasticity and plasticity, and energy-release rates due to fracture propagation. Here the show the applied mechanics models that will collapse in a variational model for formability map construction.

Gomes, E. [Universidade de Sao Paulo (Brazil); Filho, E.B. [Universidade Estadual de Campinas (Brazil)

1995-12-31

220

Processing and nanostructure influences on mechanical properties of thermoelectric materials  

NASA Astrophysics Data System (ADS)

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.

Schmidt, Robert David

221

Ion Trap Quantum Computing with Ca + Ions  

Microsoft Academic Search

The scheme of an ion trap quantum computer is described and the implementation of quantum gate operations with trapped Ca+ ions is discussed. Quantum information processing with Ca+ ions is exemplified with several recent experiments investigating entanglement of ions.

R. Blatt; H. Häffner; C. F. Roos; C. Becher; F. Schmidt-Kaler

2004-01-01

222

Ion Trap Quantum Computing with Ca + Ions  

Microsoft Academic Search

The scheme of an ion trap quantum computer is described and the implementation of quantum gate operations with trapped Ca+ ions is discussed. Quantum information processing with Ca+ ions is exemplified with several recent experiments investigating entanglement of ions.

R. Blatt; H. Häffner; C. F. Roos; C. Becher; F. Schmidt-Kaler

223

Conscious processing of sexual information: mechanisms of appraisal.  

PubMed

To elucidate some of the activational mechanisms of sexual response, this study investigated the effects of conscious appraisal of sexual and neutral stimuli on a categorization task and on ratings of sexual arousal. Conscious appraisal is dependent on memory, regulatory, and attentional processes, interacting with one another. It is proposed that regulation is activated by attention, furnished by representations from implicit and explicit memory. Participants (26 men and 25 women) were asked to respond to "target" stimuli that were preceded by supraliminal "prime" stimuli. Primes and targets were operationalized by slides with sexual (i.e., romantic vs. explicit) and neutral content. In a cognitive task, participants had to group randomly presented targets as quickly as possible into sexual and nonsexual categories. Categorization of sexual targets was delayed when they were preceded by sexual primes compared to neutral primes. This was interpreted as an inhibitory process and compared with the Sexual Content-Induced Delay phenomenon (J. H. Geer & H. S. Bellard, 1996; J. H. Geer & J. S. Melton, 1997). No gender difference was found. In a subsequent affective task, participants provided an assessment of sexual arousal, followed by an evaluation of the target. This task was hypothesized to result in differential access to memory, where assessments of sexual arousal are influenced mainly by implicit memory, and where evaluations are influenced mainly by explicit memory. Gender differences were most prominent in the evaluation aspect of this task. It was concluded that cognitive processing of sexual information is similar for both genders, but that gender differences are present in affective processing of sexual information. PMID:15162083

Spiering, Mark; Everaerd, Walter; Laan, Ellen

2004-08-01

224

Association between central auditory processing mechanism and cardiac autonomic regulation  

PubMed Central

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

2014-01-01

225

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

PubMed

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

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

1987-01-01

226

Medial Efferent Mechanisms in Children with Auditory Processing Disorders  

PubMed Central

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

Mishra, Srikanta K.

2014-01-01

227

A method for trapping breeding adult American Oystercatchers  

USGS Publications Warehouse

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.

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

2005-01-01

228

Continuous stopping and trapping of neutral atoms  

Microsoft Academic Search

Neutral-sodium atoms have been continuously loaded into a 0.1-K deep superconducting magnetic trap with laser light used to slow and stop them. At least 10⁹ atoms were trapped with a decay time of 2 1\\/2 min. The fluorescence of the trapped atoms was studied as a function of time; possible loss mechanisms from the trap are discussed.

V. S. Bagnato; G. P. Lafyatis; A. G. Martin; E. L. Raab; R. N. Ahmad-Bitar; D. Pritchard

1987-01-01

229

Continuous stopping and trapping of neutral atoms  

SciTech Connect

Neutral-sodium atoms have been continuously loaded into a 0.1-K deep superconducting magnetic trap with laser light used to slow and stop them. At least 10/sup 9/ atoms were trapped with a decay time of 2 1/2 min. The fluorescence of the trapped atoms was studied as a function of time; possible loss mechanisms from the trap are discussed.

Bagnato, V.S.; Lafyatis, G.P.; Martin, A.G.; Raab, E.L.; Ahmad-Bitar, R.N.

1987-05-25

230

Effect of chemical mechanical planarization processing conditions on polyurethane pad properties  

E-print Network

Chemical Mechanical Planarization (CMP) is a vital process used in the semiconductor industry to isolate and connect individual transistors on a chip. However, many of the fundamental mechanisms of the process are yet to ...

Ng, Grace Siu-Yee, 1980-

2003-01-01

231

Principles of an enhanced MBR-process with mechanical cleaning.  

PubMed

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

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

2011-01-01

232

Antibiotic Trapping by Plasmid-Encoded CMY-2 ?-Lactamase Combined with Reduced Outer Membrane Permeability as a Mechanism of Carbapenem Resistance in Escherichia coli  

PubMed Central

A liver transplant patient was admitted with cholangitis, for which meropenem therapy was started. Initial cultures showed a carbapenem-susceptible (CS) Escherichia coli strain, but during admission, a carbapenem-resistant (CR) E. coli strain was isolated. Analysis of the outer membrane protein profiles showed that both CS and CR E. coli lacked the porins OmpF and OmpC. Furthermore, PCR and sequence analysis revealed that both CS and CR E. coli possessed blaCTX-M-15 and blaOXA-1. The CR E. coli strain additionally harbored blaCMY-2 and demonstrated a >15-fold increase in ?-lactamase activity against nitrocefin, but no hydrolysis of meropenem was detected. However, nitrocefin hydrolysis appeared strongly inhibited by meropenem. Furthermore, the CMY-2 enzyme demonstrated lower electrophoretic mobility after its incubation either in vitro or in vivo with meropenem, indicative of its covalent modification with meropenem. The presence of the acyl-enzyme complex was confirmed by mass spectrometry. By transformation of the CMY-2-encoding plasmid into various E. coli strains, it was established that both porin deficiency and high-level expression of the enzyme were needed to confer meropenem resistance. In conclusion, carbapenem resistance emerged by a combination of elevated ?-lactamase production and lack of porin expression. Due to the reduced outer membrane permeability, only small amounts of meropenem can enter the periplasm, where they are trapped but not degraded by the large amount of the ?-lactamase. This study, therefore, provides evidence that the mechanism of “trapping” by CMY-2 ?-lactamase plays a role in carbapenem resistance. PMID:23733461

van der Bij, Akke K.; van Boxtel, Ria; Pitout, Johann D. D.; van Ulsen, Peter; Melles, Damian C.; Tommassen, Jan

2013-01-01

233

Ion traps fabricated in a CMOS foundry  

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

234

Ion traps fabricated in a CMOS foundry  

E-print Network

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.

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

2014-06-13

235

Thermoelectrically cooled water trap  

DOEpatents

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.

Micheels, Ronald H. (Concord, MA)

2006-02-21

236

Alternative interpretations of low-energy nuclear reaction processes with deuterated metals based on the Bose-Einstein condensation mechanism  

E-print Network

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.

Yeong E. Kim; Thomas O. Passell

237

Trapping and cooling of 174Yb+ ions in a microfabricated surface trap  

NASA Astrophysics Data System (ADS)

Trapped atomic ions are the leading candidate to act as individual quantum bits in a large quantum information processing system. Ion traps can be conformed to a two-dimensional surface, which provides a way to increase the number of ions while maintaining the ability to move individual ions in a two-dimensional grid. However, surface traps tend to suffer from shallow trap depths and higher motional heating rates. In this work, we report the design, fabrication, and testing of a simple gold-on-fused-silica ion trap optimized for a deep trapping potential and stable motional modes. The desirable trap characteristics include long lifetime, fully-compensated micromotion, and high secular trap frequencies that were measured using a trapped and cooled 174Yb+ ion. This trap design can be integrated with an optical cavity to enhance the ion-photon coupling.

Noek, Rachel; Kim, Taehyun; Mount, Emily; Baek, So-Young; Maunz, Peter; Kim, Jungsang

2013-08-01

238

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

SciTech Connect

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.

French, Jarrod B.; Cen, Yana; Sauve, Anthony A.; Ealick, Steven E. (Cornell); (Weill-Med)

2010-11-11

239

Research and Application on Typical Process Knowledge Discovery in Mechanical Manufacturing Enterprise  

Microsoft Academic Search

The source and composing of process planning knowledge is analyzed based on the state of art in discrete mechanical manufacturing enterprise. On the basis of the widely application of computer aided process planning system (CAPP) in mechanical manufacturing enterprise, the concept of process planning knowledge discovery (PPKD) is proposed for product process planning database. CAPPFramework (a CAPP development platform that

Xiaoliang Jia; Zhenming Zhang; Xitian Tian

2008-01-01

240

Ripple Trap  

NASA Technical Reports Server (NTRS)

3 April 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the margin of a lava flow on a cratered plain in the Athabasca Vallis region of Mars. Remarkably, the cratered plain in this scene is essentially free of bright, windblown ripples. Conversely, the lava flow apparently acted as a trap for windblown materials, illustrated by the presence of the light-toned, wave-like texture over much of the flow. That the lava flow surface trapped windblown sand and granules better than the cratered plain indicates that the flow surface has a rougher texture at a scale too small to resolve in this image.

Location near: 10.7oN, 204.5oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Winter

2006-01-01

241

CO2-ECBM related coupled physical and mechanical transport processes  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

242

Interaction of trapped ions with trapped atoms  

E-print Network

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 ...

Grier, Andrew T. (Andrew Todd)

2011-01-01

243

Positron trapping at vacancies in electron-irradiated Si at low temperatures  

SciTech Connect

Experimental results on positron trapping at vacancies in electron-irradiated silicon are presented. The positron lifetimes 273 +- 3 and 248 +- 2 ps in pure Si and heavily-phosphorus-doped Si ((P) = 10/sup 20/ cm/sup -3/) are assigned to a negative monovacancy V/sup -/ and a negative vacancy-phosphorus pair (V-P)/sup -/, respectively. In pure Si, positron trapping displays a strong negative temperature dependence, and the specific trapping rate reaches very large values (10/sup 17//sup --/10/sup 18/ s/sup -1/) at low temperatures. In Si:P the trapping rate is independent of temperature. These different temperature behaviors are attributed to different positron-trapping mechanisms, a cascade of one-phonon transitions in pure Si, and an Auger process in Si:P.

Maekinen, J.; Corbel, C.; Hautojaervi, P.; Moser, P.; Pierre, F.

1989-05-15

244

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

...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...

2014-07-01

245

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

Code of Federal Regulations, 2011 CFR

...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...

2011-07-01

246

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

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

247

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

Code of Federal Regulations, 2010 CFR

...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...

2010-07-01

248

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

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

249

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

NASA Astrophysics Data System (ADS)

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

Kim, Taehyun; Maunz, Peter; Kim, Jungsang

2011-12-01

250

Low-Temperature Polycrystalline Silicon Thin Film Transistor Nonvolatile Memory Using Ni Nanocrystals as Charge-Trapping Centers Fabricated by Hydrogen Plasma Process  

NASA Astrophysics Data System (ADS)

Processes for fabricating a Ni nanocrystal (NC)-assisted low-temperature polycrystalline silicon thin film transistor (LTPS-TFT) nonvolatile memory device of noble stack below 600 °C were successfully developed. The NCs were fabricated in H-plasma atmosphere by heating a nanosized Ni film to realize an appropriate nanoparticle distribution. Results show that NCs with a number density of ?5×1011 cm-2 and a particle diameter of 4 to 12 nm can successfully be fabricated as charge-trapping centers for enhancing the device performance. The results also indicate that the data retentions at the initial time and after 104 s for a SiO2/Ni-NCs/Si3N4/SiO2 gate under the present stack of devices are about 2.2 and ?1.1 V, respectively.

Tai-Jui Wang, Terry; Gao, Pei-Ling; Cheng-Yu Ma, William; Kuo, Cheng-Tzu

2010-06-01

251

CO2-ECBM related coupled physical and mechanical transport processes  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

252

CO2-ECBM related coupled physical and mechanical transport processes  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

253

zTrap: zebrafish gene trap and enhancer trap database  

Microsoft Academic Search

BACKGROUND: We have developed genetic methods in zebrafish by using the Tol2 transposable element; namely, transgenesis, gene trapping, enhancer trapping and the Gal4FF-UAS system. Gene trap constructs contain a splice acceptor and the GFP or Gal4FF (a modified version of the yeast Gal4 transcription activator) gene, and enhancer trap constructs contain the zebrafish hsp70l promoter and the GFP or Gal4FF

Koichi Kawakami; Gembu Abe; Tokuko Asada; Kazuhide Asakawa; Ryuichi Fukuda; Aki Ito; Pradeep Lal; Naoko Mouri; Akira Muto; Maximilliano L Suster; Hitomi Takakubo; Akihiro Urasaki; Hironori Wada; Mikio Yoshida

2010-01-01

254

Processing effects on the mechanical properties of tungsten heavy alloys  

NASA Technical Reports Server (NTRS)

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

Kishi, Toshihito; German, R. M.

1990-01-01

255

Thermo-Mechanical Processing in Friction Stir Welds  

NASA Technical Reports Server (NTRS)

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.

Schneider, Judy

2003-01-01

256

Mouse Trap Racing in the Computer Age!  

NSDL National Science Digital Library

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

AMPS GK-12 Program,

257

Ion-trapping properties of SCRIT  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

258

Temperature-dependent carrier trapping processes in short period quantum wire superlattices grown by flow rate modulation epitaxy  

Microsoft Academic Search

We report the first systematic investigation of the temperature-dependent carrier transferring processes of very short period V-grooved GaAs\\/AlGaAs quantum wire superlattice structures grown by flow rate-modulated metal-organic vapor phase epitaxy. The one monolayer (1 ML) fluctuation causes carrier confinement in sidewall (111) facet superlattice structures, and is shown to play an important role in the carrier transferring process. At low

X. Q. Liu; A. Sasaki; N. Ohno; Xue-Lun Wang; Mutsuo Ogura

2000-01-01

259

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 ...

260

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

NASA Astrophysics Data System (ADS)

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.

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

2015-03-01

261

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...

262

A tethering mechanism for length control in a processive carbohydrate polymerization  

E-print Network

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

Gleeson, Joseph G.

263

Cognitive procedural learning in early Alzheimer's disease: impaired processes and compensatory mechanisms  

E-print Network

Cognitive procedural learning in early Alzheimer's disease: impaired processes and compensatory-order cognitive processes (i.e., compensatory mechanisms) to perform the procedural task. Keywords: procedural neurologie, Caen, France Short title: Cognitive procedural learning in Alzheimer's disease. Corresponding

Paris-Sud XI, Université de

264

Testing for Dark Matter Trapped in the Solar System  

NASA Technical Reports Server (NTRS)

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.

Krisher, Timothy P.

1996-01-01

265

Copper ion-exchanged channel waveguides optimization for optical trapping.  

PubMed

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

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

2013-08-01

266

Fluid mechanics mechanisms in the stall process of airfoils for helicopters  

NASA Technical Reports Server (NTRS)

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.

Young, W. H., Jr.

1981-01-01

267

On the Physical Mechanism of NBTI in Silicon Oxynitride p-MOSFETs: Can Differences in Insulator Processing Conditions Resolve the Interface  

E-print Network

On the Physical Mechanism of NBTI in Silicon Oxynitride p-MOSFETs: Can Differences in Insulator TNO devices show different NBTI behavior, and can be attributed to additional contribution from hole results. [Keywords: NBTI, plasma and thermal nitridation, interface traps, hole trapping, reaction

Alam, Muhammad A.

268

Evaluating the Learning Process of Mechanical CAD Students  

ERIC Educational Resources Information Center

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…

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

2007-01-01

269

METAL FORMING PROCESSES IMPROVEMENT BY CONTINUUM DAMAGE MECHANICS  

Microsoft Academic Search

In this work, a fully coupled constitutive equations accounting for both combined isotropic and kinematic hardening as well as the ductile damage is implemented into the general purpose Finite Element code for metal forming simulation. First, the fully coupled anisotropic constitutive equations in the framework of Continuum Damage Mechanics are presented. Attention is paid to the strong coupling between the

K. SAANOUNI

270

Elementary Quantum Mechanics in a High-Energy Process  

ERIC Educational Resources Information Center

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)

Denville, A.; And Others

1978-01-01

271

Psychophysical evidence for a functional hierarchy of motion processing mechanisms  

E-print Network

. INTRODUCTION Contemporary modelers of motion perception typically postulate local mechanisms that are selective adaptation to the motion of the edges of square patterns. Out-of-phase oscillation of op- posite edges- lation of the square, with no change in size. Out-of- phase adaptation raised thresholds for detecting

Makous, Walter

272

Reduce Steam Trap Failures at Chambers Works  

E-print Network

Reduce Steam Trap Failures at Chambers Works GB/BB Name: Cyndi Kouba Mentor/MBB: Andrew Degraff Team Members Michael Crowley(Site Energy Lead), (Charlie) Flanigan (Aramids-maintenance), Ben Snyder (Aramids-ATO), Michael Scruggs (Central... Maintenance Mechanic), Rick Ragsdale (Fluor), Joyce Finkle (PC), Denis P Humphreys (Fluoroproducts), Jack Hemmert, Charlie Brown 10/20/2010 2 Steam trap failures are nothing new Steam trap programs are nothing new WHAT makes this program have such a huge...

Kouba, C.

273

Trapping ions in a segmented ring trap  

NASA Astrophysics Data System (ADS)

We demonstrate robust trapping in an ion trap which has a ring shaped RF node. Ions are back-side loaded through a small 10 ?m diameter loading hole and we have demonstrated thousands of complete circuits around the trap. Each circuit passes through 44 trapping zones; the trap has 89 independent DC control electrodes. Measurements of the tangential secular frequency indicate a weak dependence on the RF and the loading hole. The ion trap is fabricated using four metal layers, allowing for the inner islanded electrodes to be electrically routed underneath the trap with negligible effects on the trapped ions. [4pt] 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.

Tabakov, B. P.; Sterk, J. D.; Benito, F.; Haltli, R.; Tigges, C. P.; Stick, D.; Blain, M. G.; Moehring, D. L.

2012-06-01

274

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

PubMed

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

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

2014-12-19

275

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

276

Processing and mechanical properties of autogenous titanium implant materials  

Microsoft Academic Search

Pure titanium and some of its alloys are currently considered as the most attractive metallic materials for biomedical applications due to their excellent mechanical properties, corrosion resistance, and biocompatibility. It has been demonstrated that titanium and titanium alloys are well accepted by human tissues as compared to other metals such as SUS316L stainless steel and Co–Cr–Mo type alloy. In the

C. E. Wen; Y. Yamada; K. Shimojima; Y. Chino; T. Asahina; M. Mabuchi

2002-01-01

277

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

Microsoft Academic Search

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

B. Samimy; G. Rizzoni

1996-01-01

278

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

E-print Network

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

Wei, Qiuming

279

Memory-Based Processing as a Mechanism of Automaticity in Text Comprehension  

Microsoft Academic Search

A widespread theoretical assumption is that many processes involved in text comprehension are automatic, with automaticity typically defined in terms of properties (e.g., speed, effort). In contrast, the authors advocate for conceptualization of automaticity in terms of underlying cognitive mechanisms and evaluate one prominent account, the memory-based processing account, which states that one mechanism underlying automatization involves a shift from

Katherine A. Rawson; Erica L. Middleton

2009-01-01

280

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

PubMed

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

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

281

On biodiversity conservation and poverty traps  

PubMed Central

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

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

2011-01-01

282

Mini ion trap mass spectrometer  

DOEpatents

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.

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

1995-01-01

283

Mini ion trap mass spectrometer  

DOEpatents

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.

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

1995-09-19

284

A mechanized process algebra for verification of device synchronization protocols  

NASA Technical Reports Server (NTRS)

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.

Schubert, E. Thomas

1992-01-01

285

Mechanism of silk processing in insects and spiders  

Microsoft Academic Search

Silk spinning by insects and spiders leads to the formation of fibres that exhibit high strength and toughness. The lack of understanding of the protein processing in silk glands has prevented the recapitulation of these properties in vitro from reconstituted or genetically engineered silks. Here we report the identification of emulsion formation and micellar structures from aqueous solutions of reconstituted

Hyoung-Joon Jin; David L. Kaplan

2003-01-01

286

Unusual corrosion process of gold nanoplates and the mechanism study.  

PubMed

Herein we describe an unusual localized corrosion that initiates on large {111} surfaces and ends with the complete fragmentation of the gold nanoplates, which is expected to develop into a specific method for processing large metal nanomaterials into smaller ones with desired shapes. PMID:20648310

Cheng, Yingwen; Qiu, Cuicui; Ma, Houyi; Zhang, Xiaokai; Gu, Xiaohu

2010-05-01

287

Collective memory, a fusion of cognitive mechanisms and cultural processes.  

PubMed

The paper assumes a theoretical-empirical interface exists between top-down (structural concepts) and bottom-up (cognitive mechanisms and socio-cultural interactions) approaches to collective memory. Both deal with collaborative group accounts, material culture such as artefacts and representational re-descriptive technologies. Anthropology has shown how communal life was based on story telling, rituals, artefacts, routine practices constitutive of daily life representational re-descriptions and the reproduction of implicit and explicit emotional normative belief systems embedded in kinship and social network relations. PMID:25078868

Cicourel, Aaron V

2014-07-31

288

Nanocrystalline NiA1 - processing, characterization and mechanical properties.  

SciTech Connect

Nanocrystalline ordered NiAl (n-NiAl) was successfully synthesized by an electron beam gas condensation and compacted in-situ at various temperatures. As-compacted material exhibits grain sizes between 2 and 4 nm and densities between 78 and 94% of the theoretical density, increasing with increasing compaction temperature above all as a result of reduced porosity. The nanocrystalline structure of NiAl is stable up to about 1000 C. Microhardness of as compacted n-NiAl increases with increasing density, above all as a result of reduced porosity. For the reasons not fully understood yet, microhardness of n-NiAl increases also with increasing grain size following annealing, a response different from that in the conventional, coarse-grained NiAl, The present material is significantly stronger than its conventional counterpart but not as strong as predicted by Hall-Petch-type modeling. Also, in the nanocrystalline form, NiAl exhibits room temperature ductility, unlike its coarse-grained counterpart. The present study provides probably the first unequivocal experimental evidence of the room temperature ductility of a nanocrystalline intermetallic material. The mechanical behavior of n-NiAl can be rationalized assuming that diffusional, rather than dislocation, mechanisms control strength and ductility of n-materials.

Choudry, M. S.; Dollar, M.; Eastman, J. A.; Materials Science Division; Westinghouse Electric Corp.; Illinois Inst. of Tech.

1998-11-15

289

Orientation processing mechanisms revealed by the plaid tilt illusion  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

290

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)

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.

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

2012-12-01

291

Reconstruction of mechanically recorded sound by image processing  

SciTech Connect

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.

Fadeyev, Vitaliy; Haber, Carl

2003-03-26

292

Flexible aerogel composite for mechanical stability and process of fabrication  

DOEpatents

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.

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

2000-01-01

293

Flexible aerogel composite for mechanical stability and process of fabrication  

DOEpatents

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.

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

1999-01-01

294

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

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

295

A comparison of monkey and human motion processing mechanisms  

Microsoft Academic Search

Single-cell recording studies have provided vision scientists with a detailed understanding of motion processing at the neuronal level in non-human primates. However, despite the development of brain imaging techniques, it is not known to what extent the response characteristics of motion-sensitive neurons in monkey brain mirror those of human motion-sensitive neurons. Using a motion adaptation paradigm, the direction aftereffect, we

Catherine Lynn; William Curran

2010-01-01

296

Neutrophil extracellular traps sequester circulating tumor cells and promote metastasis  

PubMed Central

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

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

2013-01-01

297

Towards a complete multiple-mechanism account of predictive language processing.  

PubMed

Although we agree with Pickering & Garrod (P&G) that prediction-by-simulation and prediction-by-association are important mechanisms of anticipatory language processing, this commentary suggests that they: (1) overlook other potential mechanisms that might underlie prediction in language processing, (2) overestimate the importance of prediction-by-association in early childhood, and (3) underestimate the complexity and significance of several factors that might mediate prediction during language processing. PMID:23790143

Mani, Nivedita; Huettig, Falk

2013-08-01

298

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

SciTech Connect

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.

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

2007-04-07

299

Mechanism of silk processing in insects and spiders  

NASA Astrophysics Data System (ADS)

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

Jin, Hyoung-Joon; Kaplan, David L.

2003-08-01

300

Quantum Mechanics and Perceptive Processes: A Reply to Elio Conte  

NASA Astrophysics Data System (ADS)

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.

Ghirardi, GianCarlo

2014-11-01

301

A quantum mechanical model of Rabi oscillations between two interacting harmonic oscillator modes and the interconversion of modes in a Penning trap  

Microsoft Academic Search

When a Penning trap is operated with an additional quadrupole driving field with a frequency that equals a suitable combination (sum or difference) of the frequencies of the fundamental modes of motion (modified cyclotron, magnetron and axial frequency), then a periodic conversion of the participating modes into each other is observed, strongly resembling the Rabi oscillations in a 2-level atom

Martin Kretzschmar

1999-01-01

302

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

SciTech Connect

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.

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

1996-07-01

303

Mechanisms of shark skin suppression by novel polymer processing aids  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

304

Processing and mechanical behavior of hypereutectoid steel wires  

SciTech Connect

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.

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

1996-06-25

305

Improved Linear-Ion-Trap Frequency Standard  

NASA Technical Reports Server (NTRS)

Improved design concept for linear-ion-trap (LIT) frequency-standard apparatus proposed. Apparatus contains lengthened linear ion trap, and ions processed alternately in two regions: ions prepared in upper region of trap, then transported to lower region for exposure to microwave radiation, then returned to upper region for optical interrogation. Improved design intended to increase long-term frequency stability of apparatus while reducing size, mass, and cost.

Prestage, John D.

1995-01-01

306

Volatile Release From The Siberian Traps Inferred From Melt Inclusions  

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

307

BRAIN AND COGNITION 4, 171-196 (1985) Cognitive Mechanisms in Number Processing and  

E-print Network

BRAIN AND COGNITION 4, 171-196 (1985) Cognitive Mechanisms in Number Processing and Calculation for the cognitive analysis of number processing and calculation. Within this framework the primary objective and classifying cognitive deficits necessarily involves as- sumptions about normal cognitive processing

Caramazza, Alfonso

308

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

SciTech Connect

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

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

2012-01-01

309

Development and validation of a liquid chromatography/linear ion trap mass spectrometry method for the quantitative determination of deoxynivalenol-3-glucoside in processed cereal-derived products.  

PubMed

Cereal-based food can be frequently contaminated by the presence of mycotoxins derived from Fusarium fungus, and, in particular, by deoxynivalenol (DON). Nowadays, analytical strategies for the detection of DON are well developed, but there are gaps for what concerns a correct identification, quantification and toxicological evaluation of the respective metabolites, mainly related to detoxifying actions via plant metabolism or to processing technologies and also referred to as "masked" mycotoxins. Here, we report the development of a liquid chromatography/linear ion trap mass spectrometry method capable of determining deoxynivalenol-3-glucoside (DON-3G), which is the main known DON metabolite, in different processed cereal-derived products. Samples were extracted with a mixture of methanol/water (80:20; v/v) and cleaned up using immunoaffinity columns. Chromatographic separation was performed using a core-shell C(18) column with an aqueous acetic acid/methanol mixture as the mobile phase under gradient conditions. The method was in-house validated on a bread matrix as follows: matrix-matched linearity (r(2)>0.99) was established in the range of 10-200 ?g kg(-1); trueness expressed as recovery was close to 90%; good intermediate precision (overall RSD<9%) and adequate detection quantitation limits (4 and 11 ?g kg(-1), respectively) were achieved. Furthermore, applying a metrology approach based on intralaboratory data, the estimated measurement expanded uncertainty was determined to be equal to 29%. The reliability of the method was finally demonstrated in bread, cracker, biscuit and minicake commodities, resulting in relatively low levels of DON-3G, which were not higher than 30 ?g kg(-1). PMID:23194564

Suman, M; Bergamini, E; Catellani, D; Manzitti, A

2013-02-15

310

Autophagic Processes in Yeast: Mechanism, Machinery and Regulation  

PubMed Central

Autophagy refers to a group of processes that involve degradation of cytoplasmic components including cytosol, macromolecular complexes, and organelles, within the vacuole or the lysosome of higher eukaryotes. The various types of autophagy have attracted increasing attention for at least two reasons. First, autophagy provides a compelling example of dynamic rearrangements of subcellular membranes involving issues of protein trafficking and organelle identity, and thus it is fascinating for researchers interested in questions pertinent to basic cell biology. Second, autophagy plays a central role in normal development and cell homeostasis, and, as a result, autophagic dysfunctions are associated with a range of illnesses including cancer, diabetes, myopathies, some types of neurodegeneration, and liver and heart diseases. That said, this review focuses on autophagy in yeast. Many aspects of autophagy are conserved from yeast to human; in particular, this applies to the gene products mediating these pathways as well as some of the signaling cascades regulating it, so that the information we relate is relevant to higher eukaryotes. Indeed, as with many cellular pathways, the initial molecular insights were made possible due to genetic studies in Saccharomyces cerevisiae and other fungi. PMID:23733851

Reggiori, Fulvio; Klionsky, Daniel J.

2013-01-01

311

A comparison of monkey and human motion processing mechanisms.  

PubMed

Single-cell recording studies have provided vision scientists with a detailed understanding of motion processing at the neuronal level in non-human primates. However, despite the development of brain imaging techniques, it is not known to what extent the response characteristics of motion-sensitive neurons in monkey brain mirror those of human motion-sensitive neurons. Using a motion adaptation paradigm, the direction aftereffect, we recently provided evidence of a strong resemblance in the response functions of motion-sensitive neurons in monkey and human to moving dot patterns differing in dot density. Here we describe a series of experiments in which measurements of the direction aftereffect are used to infer the response characteristics of human motion-sensitive neurons when viewing transparent motion and moving patterns that differ in their signal-to-noise ratio (motion coherence). In the case of transparent motion stimuli, our data suggest suppressed activity of motion-sensitive neurons similar to that reported for macaque monkey. In the case of motion coherence, our results are indicative of a linear relationship between signal intensity (coherence) and neural activity; a pattern of activity which also bears a striking similarity to macaque neural activity. These findings strongly suggest that monkey and human motion-sensitive neurons exhibit similar response and inhibitory characteristics. PMID:20705083

Lynn, Catherine; Curran, William

2010-10-12

312

PVP Protective mechanism of palladium nanoparticles obtained by sonochemical process  

NASA Astrophysics Data System (ADS)

The protective effect of polyvinylpyrrolidone (PVP) on the palladium nanoparticles has been investigated using Fourier Transform Infrared Spectroscopy (FT-IR). Palladium nanoparticles have been obtained by ultrasonic irradiation of Pd(NO3)2 solution in presence of ethylene glycol (EG) and PVP. The sonochemical reduction process of palladium ions (Pd(II)) to palladium atoms (Pd(0)) can be explained by considering the intense ultrasonic waves that are strong enough to produce cavitation: formation, growth and collapse of bubbles. The UV-Visible absorption spectroscopy revealed that the reduction of Pd (II) to metallic Pd has been successfully achieved. The FT-IR spectroscopy spectra analysis show that, in presence of ethylene glycol, the stabilization of the nanoparticles results from the adsorption of the PVP chain on the palladium particle surface via the coordination of the PVP carbonyl group to the palladium atoms. The transmission electron microscopy (HRTEM) and electrondispersive X-ray (EDX) results confirm the dispersion, the nanometric size and the composition of the obtained palladium particles.

Nemamcha, A.; Moumeni, H.; Rehspringer, J. L.

2009-11-01

313

Mechanical Properties, Thermal Stability and Radiation Damage of Ferritic Steels Processed by Thermal Mechanical Treatments  

E-print Network

AISI American Iron and Steel Institute ASTM American Society of Mechanical Engineers ASME American Society for Testing Materials bcc or BCC Body Centered Cubic CG Coarse Grain CNB Chromium-Nickel Balance DBTT Ductile to Brittle... Loss Spectroscopy FIM Field Ion Microscopy fcc or FCC Face Centered Cubic viii FFTF Fast Flux Test Facility FIB Focused Ion Beam F/M Ferritic/Martensitic GB Grain Boundary GFR Gas Fast Reactors GNB Geometry Necessary...

Song, Miao

2014-08-04

314

Manufacturing a thin wire electrostatic trap for ultracold polar molecules  

SciTech Connect

We present a detailed description on how to build a thin wire electrostatic trap (TWIST) for ultracold polar molecules. It is the first design of an electrostatic trap that can be superimposed directly onto a magneto-optical trap (MOT). We can thus continuously produce ultracold polar molecules via photoassociation from a two species MOT and instantaneously trap them in the TWIST without the need for complex transfer schemes. Despite the spatial overlap of the TWIST and the MOT, the two traps can be operated and optimized completely independently due to the complementary nature of the utilized trapping mechanisms.

Kleinert, J.; Haimberger, C.; Zabawa, P. J.; Bigelow, N. P. [Department of Physics and Astronomy and Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14627 (United States)

2007-11-15

315

Processing and mechanical behavior of aluminium oxide microstructure composites  

NASA Astrophysics Data System (ADS)

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

Pavlacka, Robert J.

316

Dissociable Brain Mechanisms for Processing Social Exclusion and Rule Violation  

PubMed Central

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

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

2010-01-01

317

A two species trap for chromium and rubidium atoms  

E-print Network

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.

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

2004-01-20

318

Chip-scale modeling of pattern dependencies in copper chemical mechanical polishing processes  

E-print Network

Chemical mechanical polishing (CMP) has become a necessary processing step in the fabrication of copper interconnects. Copper CMP is recognized to suffer from pattern dependent problems such as dishing and erosion, which ...

Gbondo-Tugbawa, Tamba Edward

2002-01-01

319

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

E-print Network

on combining Displacement Discontinuity (DD) Boundary Element Method (BEM) and Finite Element Method (FEM) to solve the governing equations of thermo-poro-mechanical processes involving fracture/reservoir matrix. The integration of BEM and FEM is accomplished...

Rawal, Chakra

2012-07-16

320

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

E-print Network

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

Manga, Michael

321

Microfabricated Ion Traps  

E-print Network

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.

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

2011-01-17

322

Differences in the microstructure of iron mechanically processed powder alloyed with interstitial and substitutional elements  

Microsoft Academic Search

Mechanically processing iron powder with interstitial and substitutional elements resulted in different microstructures (grain size, rms-strains, and phases) depending upon the alloying composition. Alloying iron powder with substitutional elements (approximately 4 at% Al, Cr, Nb, and Ti) resulted in a microstructure similar to mechanically processed iron powder: grain size ?7nm, local, rms strain ?0.5%, and bcc-Fe nanograins. Small reductions in

D. C. Cook; T. H. Kim

1997-01-01

323

Nitronyl nitroxides as probes to study the mechanism of vasodilatory action of nitrovasodilators, nitrone spin traps, and nitroxides: role of nitric oxide.  

PubMed

Nitronyl nitroxides have been used to trap nitric oxide (.NO) produced during visible irradiation of nitrovasodilators such as sodium nitroprusside (Joseph et al., Biochem. Biophys. Res. Commun. 192:926-934; 1993). We have also shown that nitrone and nitroso spin traps exert a potent vasodilatory effect in the isolated perfused rat heart (Konorev et al., Free Radic. Biol. Med. 14:127-137, 1993). The objective of this study was to investigate the effect of nitronyl nitroxides on the vasodilatory action of sodium nitroprusside (SNP), S-nitroso-N-acetylpenicillamine (SNAP), alpha-(4-pyridyl-1-oxide)-N-tert-butyl nitrone (POBN) and 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy free radical (TEMPOL) in the isolated perfused rat heart model. In this study, we have used the following nitronyl nitroxides as nitric oxide traps: 2-(p-carboxyphenyl)-4,4,5,5-tetramethyl imidazoline-3-oxide 1-oxyl (SLI) and 2(1',1'-dimethyl-2'-hydroxyethyl)-4,4,5,5-tetramethyl imidazoline-3-oxide 1-oxyl (SLII). Under in vitro conditions, both SLI and SLII trapped .NO released from SNP/light treatment and from spontaneous decomposition of SNAP, forming the corresponding imino nitroxides, which were characterized by electron spin resonance (ESR) technique. In isolated hearts, SNP (2 mumol/l) and SNAP (20 mumol/l) increased coronary flow rate to a maximum of 185% and 190%, respectively. SNP-induced vasodilation was inhibited by SLI (0.05-3 mmol/l) from 162% to 131% of baseline, and SNAP-induced vasodilation was inhibited by SLII (0.05-1.2 mmol/l) from 190% to 136% of baseline. In contrast, neither SLI nor SLII inhibited the vasodilatory action elicited by POBN or TEMPOL.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7744299

Konorev, E A; Tarpey, M M; Joseph, J; Baker, J E; Kalyanaraman, B

1995-02-01

324

Static and dynamic mechanical properties of boron carbide processed by spark plasma sintering  

Microsoft Academic Search

Spark plasma sintering (SPS) has become a popular technique for the densification of covalent ceramics. The present investigation is focused on the static mechanical properties and dynamic compressive behavior of SPS consolidated boron carbide powder without any sintering additives. Fully dense boron carbide bodies were obtained by a short high temperature SPS treatment. The mechanical properties of the SPS-processed material,

S. Hayun; M. P. Dariel; N. Frage; E. Zaretzky

2009-01-01

325

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

326

Trapped Inflation  

SciTech Connect

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.

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

2009-06-19

327

Age and sex selectivity in trapping mule deer  

SciTech Connect

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

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

1982-01-01

328

Steam Traps-The Oft Forgotten Energy Conservation Treasure  

E-print Network

. Tbe thermostatic element in this trap typically has a large orifice and is especia ly prone to failure. This failure is masked by the continuous discharge of condensate exiting t rough the float mechanism into a common discharge ort at the bottom... traps frequently corroded resulting in a major steam loss due to the typically oversized trap orifice. Particularly horrifying were the several instances involving low pressure comfort heat application where "cheap" bellows traps were used...

Pychewicz, F. S.

329

Atomic Mechanism of Dynamic Electrochemical Lithiation Processes of MoS2 Nanosheets  

E-print Network

Atomic Mechanism of Dynamic Electrochemical Lithiation Processes of MoS2 Nanosheets Lifen Wang, Zhi has a good cycling behavior at 2 V of discharging voltage, even at low temperature.9 Research, realizing a real-time imaging characterization of the electrochemical process at the atomic level

Wang, Wei Hua

330

Particle design Part B: batch quasi-emulsion process and mechanism of grain formation of ketoprofen  

Microsoft Academic Search

This study deals with the spherical crystallization process by the quasi-emulsion mechanism, applied to a pharmaceutical. The objective is to produce spherical agglomerates made of a number of small crystals of the drug, having properties adequate for direct compression when manufacturing tablets. The aim of this work is to make the link between the process and these properties. The different

F. Espitalier; B. Biscans; C. Laguérie

1997-01-01

331

Relict olivine grains, chondrule recycling, and implications for the chemical, thermal, and mechanical processing  

E-print Network

Relict olivine grains, chondrule recycling, and implications for the chemical, thermal other incompatible ele- ments in olivine. Terrestrial weathering in a hot desert environment may have repeated thermal, chemical, and mechanical process- ing during a ``recycling" process over an extended time

332

Mechanism and design of intermittent aeration activated sludge process for nitrogen removal  

Microsoft Academic Search

The paper provided a comprehensive evaluation of the mechanism and design of intermittent aeration activated sludge process for nitrogen removal. Based on the specific character of the process the total cycle time, (TC), the aerated fraction, (AF), and the cycle time ratio, (CTR) were defined as major design parameters, aside from the sludge age of the system. Their impact on

Oytun Hanhan; Güçlü Insel; Nevin Ozgur Yagci; Nazik Artan; Derin Orhon

2011-01-01

333

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

Microsoft Academic Search

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

Kolarik; Robert V

2005-01-01

334

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

ERIC Educational Resources Information Center

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…

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

2011-01-01

335

Volatile Release from the Siberian Traps Inferred from Melt Inclusions  

NASA Astrophysics Data System (ADS)

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.

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

2009-12-01

336

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)

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.

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

337

Optimized Bose-Einstein-condensate production in a dipole trap based on a 1070-nm multifrequency laser: Influence of enhanced two-body loss on the evaporation process  

NASA Astrophysics Data System (ADS)

We present an optimized strategy for the production of tightly confined Bose-Einstein condensates (BEC) of 87Rb in a crossed dipole trap with direct loading from a magneto-optical trap. The dipole trap is created with light of a multifrequency fiber laser with a center wavelength of 1070 nm. Evaporative cooling is performed by ramping down the laser power only. A comparison of the resulting atom number in an almost pure BEC to the initial atom number and the value for the gain in phase space density per atom lost confirm that this straightforward strategy is very efficient. We observe that the temporal characteristics of evaporation sequence are strongly influenced by power-dependent two-body losses resulting from enhanced optical pumping to the higher-energy hyperfine state. We characterize these losses and compare them to results obtained with a single-frequency laser at 1030 nm.

Lauber, T.; Küber, J.; Wille, O.; Birkl, G.

2011-10-01

338

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

SciTech Connect

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

Gilson, Erik P.; Davidson, Ronald C.; Efthimion, Philip C.; Majeski, Richard; Startsev, Edward A.; Wang, Hua [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)] [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Koppell, Stewart [University of Texas at Austin, Austin, Texas 78712 (United States)] [University of Texas at Austin, Austin, Texas 78712 (United States); Talley, Matthew [Brigham Young University, Provo, Utah 84602 (United States)] [Brigham Young University, Provo, Utah 84602 (United States)

2013-05-15

339

Superconducting microfabricated ion traps  

E-print Network

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 ...

Wang, Shannon Xuanyue

340

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

341

Anisotropy in mechanical properties of high-purity copper processed by equal channel angular extrusion  

Microsoft Academic Search

High-purity oxygen-free electronic copper has been processed by equal channel angular extrusion for up to four passes at room temperature, using 90° tooling, by either route Bc or C. Small tensile specimens and compression cubes were sectioned by electro-discharge machining and tested in the as-processed condition. The equal channel angular extrusion (ECAE)-processed material was mechanically anisotropic, with the strength in

David J. Alexander; Irene J. Beyerlein

2005-01-01

342

Formation mechanisms of laboratory double layers  

NASA Technical Reports Server (NTRS)

The evolution processes of double layers were studied in a series of laboratory experiments. It was found that the existence of virtual cathode-type potential wells at the electron injection boundary was the dominant triggering mechanism. The rapid growth of the potential wells led to collisionless ion trapping and the establishment of the necessary trapped ion population. For double layers with small potential drops, collisionless ion trapping actually induced ion-ion streaming instabilities and the formation of ion phase-space vortices. In this regime, the system often exhibited relaxation-type oscillations which correspond to the disruption and the recovery of the double layers.

Chan, Chung

1987-01-01

343

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

NASA Astrophysics Data System (ADS)

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

Mansoor, Bilal

344

A Better Fly Trap  

NSDL National Science Digital Library

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

2013-02-25

345

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...

346

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

E-print Network

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

Lin, Liwei

347

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

PubMed Central

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

Hampson, Sarah E.

2011-01-01

348

Persistent Cellular Motion Control and Trapping Using Mechanotactic Signaling  

PubMed Central

Chemotactic signaling and the associated directed cell migration have been extensively studied owing to their importance in emergent processes of cellular aggregation. In contrast, mechanotactic signaling has been relatively overlooked despite its potential for unique ways to artificially signal cells with the aim to effectively gain control over their motile behavior. The possibility of mimicking cellular mechanotactic signals offers a fascinating novel strategy to achieve targeted cell delivery for in vitro tissue growth if proven to be effective with mammalian cells. Using (i) optimal level of extracellular calcium ([Ca2+?]ext mM) we found, (ii) controllable fluid shear stress of low magnitude (), and (iii) the ability to swiftly reverse flow direction (within one second), we are able to successfully signal Dictyostelium discoideum amoebae and trigger migratory responses with heretofore unreported control and precision. Specifically, we are able to systematically determine the mechanical input signal required to achieve any predetermined sequences of steps including straightforward motion, reversal and trapping. The mechanotactic cellular trapping is achieved for the first time and is associated with a stalling frequency of Hz for a reversing direction mechanostimulus, above which the cells are effectively trapped while maintaining a high level of directional sensing. The value of this frequency is very close to the stalling frequency recently reported for chemotactic cell trapping [Meier B, et al. (2011) Proc Natl Acad Sci USA 108:11417–11422], suggesting that the limiting factor may be the slowness of the internal chemically-based motility apparatus. PMID:25207940

Zhu, Xiaoying; Bouffanais, Roland; Yue, Dick K. P.

2014-01-01

349

Environmental trace analysis by ion trap mass spectrometry  

SciTech Connect

The ion trap mass spectrometer has many qualities that make it especially attractive for field environmental trace analysis. The most obvious is its demonstrated high sensitivity. The ion trap is also tolerant of high pressures; is adaptable to a variety of inlet and sampling systems; has mechanical and electrical simplicity; and can operate in an AC-only mode. We have applied the ion trap to a variety of problems in environmental analysis, which will be mentioned briefly. However, this presentation will focus on selective sampling methods for laser desorption ion trap mass spectrometry. Selective sampling methods have many advantages including the reduction of chemical noise; improved sensitivity; and, perhaps most importantly, circumvention of some of the well-known problems caused by space-charge effects. These methods include selective sorbents that both collect sample and serve as the platform for desorption ionization and resonant laser ablation to selectively ionize ablated materials for elemental analysis. Selective sorbents include zeolites and modified silica fibers. These materials provide a fast, simple, and inexpensive means to sample contaminants directly from the environmental matrix, through simple chemical modification of their surfaces, collection efficiencies can be enhanced. Resonant laser ablation is a multistep process to evaporate and subsequently ionize elemental species in a solid sample. The leading edge of a tunable laser pulse vaporizes near-surface material, while the trailing edge of the pulse resonantly excites, and subsequently ionizes, the component of interest. Preliminary data suggest that attogram detectabilities can be achieved in this fashion.

Cisper, M.E.; Garrett, A.W.; Gill, C.G.; Nogar, N.S.; Hemberger, P.H. [Los Alamos National Lab., NM (United States)

1995-12-31

350

Wear Resistant Carbide-based Thermal Sprayed Coatings: Process, Properties, Mechanical Degradation and Wear  

NASA Astrophysics Data System (ADS)

Thermally sprayed ceramic-metallic composite (CerMet) materials consist of ceramic particles mainly in form of carbides reinforced by metallic binder exhibit unique microstructural and mechanical characteristics. Such structure brings in a novel combination of hardness and toughness enabling application of this class of material in wear resistant surfaces. Final deposit microstructure that defines the mechanical properties and wear performance of material depends on process parameters and starting material characteristics. Complex interaction of in-flight particles with supersonic flame, formation of complex defective deposit structure comprising of pores, cracks and splat boundaries make comprehending of interrelation of process, microstructure, properties and performance a difficult task. Additional challenge is development of systematic understanding on mechanical degradation, damage and wear mechanisms of cermet coatings due to their complex structure. This dissertation attempts to address these issues first by taking a systematic step by step approach, process map, to establish a correlation between process, particle state, microstructure and properties. Different strategies were proposed and examined to control the high velocity thermal spray process. This strategy assessment enabled a better control over in-flight particles state in high velocity thermal spray process and provided better understanding on interaction of in-flight particles with the flame. Further, possible advantages of reducing the carbide particle size from micron to nano in terms of mechanical properties and different wear performance were explored. It was suggested that poor wear performance of nano-structured coating is due to presence of brittle phases and less available binder promotes the excessive stress detrimental to load carrying capability of material. Material damage and wear mechanisms of coating under different tribological conditions were examined. The results suggest a correlation between relative abrasive particle size/carbide particle size and observed wear mechanism. Additionally effect of surface open porosities was highlighted. A surface damage mechanisms map was developed for coatings under increasing tangential force. This work has significant implications in improved material and process design of composite wear resistant structures and systems as it provides comprehensive qualitative insight to the wear mechanism of complex composite thermally sprayed structures under different tribological contact conditions. Additionally, this work provides an establishment between process, microstructure, properties and performance for this class of materials.

Ghabchi, Arash

351

Trap-induced photoconductivity in singlet fission pentacene diodes  

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

352

Gene regulation by substoichiometric heterocomplex formation of undecameric TRAP and trimeric anti-TRAP  

PubMed Central

The control of tryptophan production in Bacillus is a paradigmatic example of gene regulation involving the interplay of multiple protein and nucleic acid components. Central to this combinatorial mechanism are the homo-oligomeric proteins TRAP (trp RNA-binding attenuation protein) and anti-TRAP (AT). TRAP forms undecameric rings, and AT assembles into triskelion-shaped trimers. Upon activation by tryptophan, the outer circumference of the TRAP ring binds specifically to a series of tandem sequences present in the 5? UTR of RNA transcripts encoding several tryptophan metabolism genes, leading to their silencing. AT, whose expression is up-regulated upon tryptophan depletion to concentrations not exceeding a ratio of one AT trimer per TRAP 11-mer, restores tryptophan production by binding activated TRAP and preventing RNA binding. How the smaller AT inhibitor prevents RNA binding at such low stoichiometries has remained a puzzle, in part because of the large RNA-binding surface on the tryptophan-activated TRAP ring and its high affinity for RNA. Using X-ray scattering, hydrodynamic, and mass spectrometric data, we show that the polydentate action of AT trimers can condense multiple intact TRAP rings into large heterocomplexes, effectively reducing the available contiguous RNA-binding surfaces. This finding reveals an unprecedented mechanism for substoichiometric inhibition of a gene-regulatory protein, which may be a widespread but underappreciated regulatory mechanism in pathways that involve homo-oligomeric or polyvalent components. PMID:24550461

Ihms, Elihu C.; Zhou, Mowei; Zhang, Yun; Kleckner, Ian R.; McElroy, Craig A.; Wysocki, Vicki H.; Gollnick, Paul; Foster, Mark P.

2014-01-01

353

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

SciTech Connect

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.

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

1996-07-01

354

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

SciTech Connect

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.

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

1996-10-01

355

Thermomechanical processing and mechanical properties of hypereutectoid steels and cast irons  

SciTech Connect

Recent advances in metallurgy of hypereutectoid steels and cast irons show that unique properties, such ultrahigh hardness and strength, and superplasticity, are achievable. This book focuses on the mechanical properties of hypereutectoid steels and cast irons as influenced by thermomechanical processing and microstructure. Some topics covered are: (1) Hot workability of hypereutectoid tool steels; (2) Thermomechanical processing of austempered ductile iron: An overview; (3) Mechanical behavior of ultrahigh strength, ultrahigh carbon steel wire and rod; and (4) Tensile elongation behavior of fine-grained Fe-C alloys at elevated temperatures.

Lesuer, D.R.; Syn, C.K.; Sherby, O.D. (eds.)

1998-01-01

356

Microparticle trapping in an ultrasonic Bessel beam  

PubMed Central

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

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

2011-01-01

357

Development of a Plastic Injection Molding Processing Laboratory for Freshman Mechanical Engineering Technology Students  

NSDL National Science Digital Library

As is the case with many educational institutions that offer a MET degree, an introductory course in manufacturing materials and processes is required. At Penn State Erie, The Behrend College, we offer first-year Mechanical Engineering Technology (MET) students the introductory manufacturing materials and processes course. The course has both a lecture and laboratory segment. During the lab segment of the course, students have the opportunity to experience: material testing, plant tours, manufacturing processes, statistical process control, and inspection/measurement techniques. With 10 PIM machines, 3 extrusion lines, 2 thermoforming machines, and 2 blow molding machines, Penn State Behrend has the largest educational plastic injection molding (PIM) laboratory in the country. Collaborative efforts were initiated between the Mechanical Engineering Technology and Plastics Engineering Technology departments to enhance the learning experience. Resulting from the collaboration a decision was made to add a PIM laboratory to emphasize the lecture on plastic materials and processes. The PIM laboratory was developed to give the student an introduction to the PIM process, machine, mold and the effects of processing variables on the parts. Also, students would gain knowledge regarding the effects of part design on the process. Prior to the implementation of this lab, the students went on plant tours or were shown videos of the PIM process.

Meckley, Jonathan A.; Nitterright, Fredrick A.

2009-07-27

358

End Uses Mechanical Properties Settled By The Modified Sintering Conditions Of The Metal Injection Molding Process  

NASA Astrophysics Data System (ADS)

Most common mechanical applications require parts with specific properties as hard faced features. It is well known that treating parts under suitable atmospheres may improve hardness and strength yield of steels. Heat treatment process and more particularly thermo-chemical diffusion processes (such as carburizing or its variation: carbonitriding) can be performed to reach the industrial hardness profile requirements. In this work, a low-alloyed steel feedstock based on water soluble binder system is submitted to the MIM process steps (including injection molding, debinding and sintering). As-sintered parts are then treated under a low pressure carbonitriding treatment. This contribution focuses on preliminary results such as microstructural analyses and mechanical properties which are established at each stage of the process to determine and monitor changes.

Marray, Tarek; Jaccquet, Philippe; Moinard-Checot, Delphine; Fabre, Agnès; Barrallier, Laurent

2011-01-01

359

The observation of trapping and detrapping effects in high-k gate dielectric MOSFETs by a new gate current Random Telegraph Noise (IG-RTN) approach  

Microsoft Academic Search

A new method, called gate current random telegraph noise (IG RTN), was developed to analyze the oxide quality and reliability of high-k gate dielectric MOSFETs. First, a single electron trapping\\/detrapping from process induced trap in nMOSFET was observed and the associated physical mechanism was proposed. Secondly, IG RTN has also been successfully applied to differentiate the difference in electron tunneling

C. M. Chang; S. S. Chung; Y. S. Hsieh; L. W. Cheng; C. T. Tsai; G. H. Ma; S. C. Chien; S. W. Sun

2008-01-01

360

Radio Frequency Generation of an Electron Plasma in a Malmberg-Penning Trap  

SciTech Connect

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.

Paroli, B. [INFN Sezione di Milano and Dipartimento di Fisica, Universita degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Dipartimento di Energia, Politecnico di Milano, P.za Leonardo da Vinci 32, 20133 Milano (Italy); De Luca, F.; Pozzoli, R.; Rome, M. [INFN Sezione di Milano and Dipartimento di Fisica, Universita degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Maero, G. [Dipartimento di Fisica, Universita degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy)

2010-06-16

361

Deadly Glue — Adhesive Traps of Carnivorous Plants  

Microsoft Academic Search

\\u000a Carnivorous plants trap and utilize animals in order to improve their supply with mineral nutrients. One strategy for prey\\u000a capture is the use of adhesive traps, i.e., leaves that produce sticky substances. Sticky shoots are widespread in the plant\\u000a kingdom and serve to protect the plant, especially flowers and seeds. In some taxa, mechanisms have been developed to absorb\\u000a nutrients

Wolfram Adlassnig; Thomas Lendl; Marianne Peroutka; Ingeborg Lang

362

Shaking-induced dynamics of cold atoms in magnetic traps  

E-print Network

We describe an experiment in which cold rubidium atoms, confined in an elongated magnetic trap, are excited by transverse oscillation of the trap centre. The temperature after excitation exhibits resonance as a function of the driving frequency. We measure these resonances at several different trap frequencies. In order to interpret the experiments, we develop a simple model that incorporates both collisions between atoms and the anharmonicity of the real three-dimensional trapping potential. As well as providing a precise connection between the transverse harmonic oscillation frequency and the temperature resonance frequency, this model gives insight into the heating and loss mechanisms, and into the dynamics of driven clouds of cold trapped atoms.

García, I Llorente; Sinclair, C D J; Curtis, E A; Tachikawa, M; Hudson, J J; Hinds, E A

2013-01-01

363

Quantum-enhanced deliberation of learning agents using trapped ions  

NASA Astrophysics Data System (ADS)

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.

Dunjko, V.; Friis, N.; Briegel, H. J.

2015-02-01

364

Trap style influences wild pig behavior and trapping success  

USGS Publications Warehouse

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.

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

2011-01-01

365

Enhanced mechanical properties of graphene/copper nanocomposites using a molecular-level mixing process.  

PubMed

RGO flakes are homogeneously dispersed in a Cu matrix through a molecular-level mixing process. This novel fabrication process prevents the agglomeration of the RGO and enhances adhesion between the RGO and the Cu. The yield strength of the 2.5 vol% RGO/Cu nanocomposite is 1.8 times higher than that of pure Cu. The strengthening mechanism of the RGO is investigated by a double cantilever beam test using the graphene/Cu model structure. PMID:23983045

Hwang, Jaewon; Yoon, Taeshik; Jin, Sung Hwan; Lee, Jinsup; Kim, Taek-Soo; Hong, Soon Hyung; Jeon, Seokwoo

2013-12-10

366

Processing and characterization of lead tin telluride-based thermoelectric materials made by mechanical alloying  

Microsoft Academic Search

The research reported in this dissertation investigates the processes required to mechanically alloy Pb1- xSnxTe and AgSbTe2 and a method of combining these two end compounds to result in (y)(AgSbTe 2)--(1 -- y)(Pb1- xSnxTe) thermoelectric materials for power generation applications. In general, traditional melt processing of these alloys has employed high purity materials that are subjected to time and energy

Aaron D. Lalonde

2010-01-01

367

Energetics and forces of the Dionaea muscipula trap closing  

Microsoft Academic Search

The Venus flytrap is the most famous carnivorous plant. The electrical stimulus between a midrib and a lobe closes the Venus flytrap upper leaf in 0.3s without mechanical stimulation of trigger hairs. Here we present results for direct measurements of the closing force of the trap of Dionaea muscipula Ellis after mechanical or electrical stimulation of the trap using the

Alexander G. Volkov; Veronica A. Murphy; Jacqueline I. Clemmons; Michael J. Curley; Vladislav S. Markin

368

Current leakage relaxation and charge trapping in ultra-porous low-k materials  

SciTech Connect

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.

Borja, Juan; Plawsky, Joel L., E-mail: plawsky@rpi.edu; Gill, William N. [Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lu, T.-M. [Department of Physics, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Bakhru, Hassaram [University at Albany's College of Nanoscale Science and Engineering (CNSE), Albany, New York 12203 (United States)

2014-02-28

369

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

NASA Astrophysics Data System (ADS)

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/SiO2 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.

Pud, S.; Gasparyan, F.; Petrychuk, M.; Li, J.; Offenhäusser, A.; Vitusevich, S. A.

2014-06-01

370

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

SciTech Connect

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.

Pud, S.; Li, J.; Offenhäusser, A.; Vitusevich, S. A., E-mail: s.vitusevich@fz-juelich.de [Peter Grünberg Institute (PGI-8), Forschungszentrum Jülich, 52425 Jülich (Germany); Gasparyan, F. [Peter Grünberg Institute (PGI-8), Forschungszentrum Jülich, 52425 Jülich (Germany); Department of Semiconductor Physics and Microelectronics, Yerevan State University, 1 Alex Manoogian St., 0025 Yerevan (Armenia); Petrychuk, M. [Radiophysics Faculty, T. Shevchenko National University of Kyiv, 60 Volodymyrska St., 01601 Kyiv (Ukraine)

2014-06-21

371

Current leakage relaxation and charge trapping in ultra-porous low-k materials  

NASA Astrophysics Data System (ADS)

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 =k0?(t+1)? -1, where 0 < ? < 1. Such dynamics have previously been observed in studies of charge 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.

Borja, Juan; Plawsky, Joel L.; Lu, T.-M.; Bakhru, Hassaram; Gill, William N.

2014-02-01

372

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

PubMed

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. PMID:20060280

Edinçliler, Ay?e; Baykal, Gökhan; Saygili, Altug

2010-06-01

373

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

PubMed

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

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

2012-09-01

374

Do conscious perception and unconscious processing rely on independent mechanisms? A meta-contrast study.  

PubMed

There is currently no consensus regarding what measures are most valid to demonstrate perceptual processing without awareness. Likewise, whether conscious perception and unconscious processing rely on independent mechanisms or lie on a continuum remains a matter of debate. Here, we addressed these issues by comparing the time courses of subjective reports, objective discrimination performance and response priming during meta-contrast masking, under similar attentional demands. We found these to be strikingly similar, suggesting that conscious perception and unconscious processing cannot be dissociated by their time course. Our results also demonstrate that unconscious processing, indexed by response priming, occurs, and that objective discrimination performance indexes the same conscious processes as subjective visibility reports. Finally, our results underscore the role of attention by showing that how much attention the stimulus receives relative to the mask, rather than whether processing is measured by conscious discrimination or by priming, determines the time course of meta-contrast masking. PMID:24398259

Peremen, Ziv; Lamy, Dominique

2014-02-01

375

Trap diversity and evolution in the family Droseraceae.  

PubMed

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

Poppinga, Simon; Hartmeyer, Siegfried R H; Masselter, Tom; Hartmeyer, Irmgard; Speck, Thomas

2013-07-01

376

Trap diversity and evolution in the family Droseraceae  

PubMed Central

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

Poppinga, Simon; Hartmeyer, Siegfried R.H.; Masselter, Tom; Hartmeyer, Irmgard; Speck, Thomas

2013-01-01

377

Effect of semi-solid processing on microstructure and mechanical properties of 5052 aluminum alloy  

Microsoft Academic Search

The microstructure and mechanical properties of rheocasted 5052 aluminum alloy were investigated. The semi-solid slurry of this alloy was prepared by ultrasonic vibration (USV) process and then shaped by gravity casting (GC) and high press diecasting (HPDC). The experimental results indicate that fine and globular primary a(Al) particles are distributed uniformly in the rheocasting samples. The tensile strength and elongation

Shu-lin LÜ; Shu-sen WU; Ze-ming ZHU; Ping AN; You-wu MAO

2010-01-01

378

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

Microsoft Academic Search

A frequency domain approach to fatigue life evaluation is an important task in the design of mechanical components subject to random loads.The greatest advantages of this method are the computational efficiency and the capability to give a synthetic representation of a random process. The importance of this method is clear, especially when it is used in the postprocessing phase of

Claudio Braccesi; Filippo Cianetti; Guido Lori; Dario Pioli

2005-01-01

379

Spectral stochastic processes arising in quantum mechanical models with a non- L 2 ground state  

Microsoft Academic Search

A functional integral representation is given for a large class of quantum mechanical models with a non- L 2 ground state. As a prototype, the particle in a periodic potential is discussed: a unique ground state is shown to exist as a state on the Weyl algebra, and a functional measure ( spectral stochastic process) is constructed on trajectories taking

J. Löffelholz; G. Morchio; F. Strocchi

1995-01-01

380

Spectral stochastic processes arising in quantum mechanical models with a non- L 2 ground state  

Microsoft Academic Search

A functional integral representation is given for a large class of quantum mechanical models with a non-L2 ground state. As a prototype, the particle in a periodic potential is discussed: a unique ground state is shown to exist as a state on the Weyl algebra, and a functional measure (spectral stochastic process) is constructed on trajectories taking values in the

J. Löffelholz; G. Morchio; F. Strocchi

1995-01-01

381

Spectral stochastic processes arising in quantum mechanical models with a non-L2 ground state  

Microsoft Academic Search

A functional integral representation is given for a large class of quantum mechanical models with a non-L2 ground state. As a prototype the particle in a periodic potential is discussed: a unique ground state is shown to exist as a state on the Weyl algebra, and a functional measure (spectral stochastic process) is constructed on trajectories taking values in the

J. Loffelholz; G. Morchio; F. Strocchi

1994-01-01

382

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

PubMed Central

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

Sakurai, Takeshi; Namiki, Shigehiro; Kanzaki, Ryohei

2014-01-01

383

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

E-print Network

1 Hydro-Mechanical Loading and Compressibility of Fibrous Media for Resin Infusion Processes P investigating the compressibility behaviour of composite preform with a view of modelling resin infusion Infusion The need for manufacturing large composite parts in the aeronautic industry is ever increasing

Paris-Sud XI, Université de

384

City of San Diego This page outlines solar PV incentives, financing mechanisms, permitting process, and  

E-print Network

solar energy system for your home or business. o Typically solar installers will: Locate financing to actual energy use and is responsible for system performance, operations and maintenance. #12; www.energycenter.org/index.php/incentive-programs/california-solarCity of San Diego This page outlines solar PV incentives, financing mechanisms, permitting process

385

Precipitation and mechanical properties of supersaturated Al-Zn-Mg alloys processed by severe plastic deformation  

E-print Network

Precipitation and mechanical properties of supersaturated Al-Zn-Mg alloys processed by severe density, precipitation. Abstract. Supersaturated Al-4.8Zn-1.2Mg-0.14Zr and Al-5.7Zn-1.9Mg-0.35Cu (wt distribution and the characteristic parameters of the dislocation structure of both Al matrix and precipitates

Gubicza, Jenõ

386

Modeling of mechanical behaviour of HSLA low carbon bainitic steel thermomechanically processed  

NASA Astrophysics Data System (ADS)

A comparative study of the microstructure characterization and mechanical properties was done in a HSLA low carbon (0.08%) bainitic steel containing boron, developed by industry as a bainitic steel grade APIX80. The steel was submitted to two different thermomechanical processes. In the first one, controlled rolling followed by accelerated cooling was applied in laboratory mill. In the second processing, specimens of the same steel were submitted to hot torsion testing. The influence of cooling conditions like start cooling temperature, cooling rates and finish cooling temperature on the microstructure and mechanical properties were investigated. The final microstructure obtained was a complex mixture of polygonal ferrite, perlite, bainite and martensite/retained austenite constituent. The use of multiple regression analysis allowed the establishment of quantitative relationships between the accelerated cooling variables and mechanical properties of the steel available from Vickers microhardness and tensile tests.

Santos, D. B.; Rodrigues, P. C. M.; Cota, A. B.

2003-10-01

387

Neutral atom traps.  

SciTech Connect

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.

Pack, Michael Vern

2008-12-01

388

Exploring Mouse Trap History  

Microsoft Academic Search

Since intelligent design (ID) advocates claimed the ubiquitous mouse trap as an example of systems that cannot have evolved,\\u000a mouse trap history is doubly relevant to studying material culture. On the one hand, debunking ID claims about mouse traps\\u000a and, by implication, also about other irreducibly complex systems has a high educational value. On the other hand, a case study

Joachim L. Dagg

389

Mechanical and Microstructural Characterization of Aluminum 6061 Processed by Plane Stress Local Torsion  

NASA Astrophysics Data System (ADS)

The process of plane stress local torsion (PSLT) has been recently proposed as localized severe plastic deformation to enhance the mechanical properties of the fastener holes. The PSLT process can create large shear strains and, consequently, substantial grain refinement in the vicinity of the hole with a gradient in the radial direction. It is of great interest and importance to investigate the effect of the PSLT process on a range of materials commonly used in the industry. An introductory investigation of mechanical and microstructural properties of Al6061 samples processed by the PSLT is performed in this work. The PSLT is simulated using the finite-element method, and the torque twist curves obtained from finite-element simulations are compared with experimental measurements. Microstructural changes and the extent of grain refinement are investigated by means of optical microscopy. It is shown that the PSLT is responsible for a considerable improvement in the mechanical properties within the deformation zone. The microhardness tests were used to measure the degree of enhancement in ultimate and yield strengths of the material processed by the PSLT.

Shamdani, Amir Hossein; Khoddam, Shahin

2014-04-01

390

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

SciTech Connect

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.

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

2006-11-01

391

Development of the Process for the Recovery and Conversion of {sup 233}UF{sub 6} Chemisorbed in NaF Traps from the Molten Salt Reactor Remediation Project  

SciTech Connect

The Molten Salt Reactor Experiment (MSRE) site at Oak Ridge National Laboratory is being cleaned up and remediated. The removal of {approx}37 kg of fissile {sup 233}U is the main activity. Of that inventory, {approx}23 kg has already been removed as UF{sub 6} from the piping system and chemisorbed in 25 NaF traps. This material is in temporary storage while it awaits conversion to a stable oxide. The planned recovery of {approx}11 kg of uranium from the fuel salt will generate another 15 to 19 NaF traps. The remaining 2 to 3 kg of uranium are present in activated charcoal beds, which are also scheduled to be removed from the reactor site. Since all of these materials (NaF traps and the uranium-laden charcoal) are not suitable for long-term storage, they will be converted to a uranium oxide (U{sub 3}O{sub 8}), which is suitable for long-term storage.The conversion of the MSRE material into an oxide presents unique problems, such as criticality concerns, a large radiation field caused by the daughters of {sup 232}U (an impurity isotope in the {sup 233}U), and the possible spread of the high-radiation field from the release of {sup 220}Rn gas. To overcome these problems, a novel process was conceived and developed. This process was specially tailored for providing remote operations inside a hot cell while maintaining full containment at all times to avoid the spread of contamination. This process satisfies criticality concerns, maximizes the recovery of uranium, minimizes any radiation exposure to operators, and keeps waste disposal to a minimum.

Cul, Guillermo D. del; Icenhour, Alan S.; Simmons, Darrell W. [Oak Ridge National Laboratory (United States)

2001-10-15

392

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

SciTech Connect

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.

Reynolds, J.T. [Shell Oil Products Co., Houston, TX (United States)

1996-07-01

393

Microstructure and Mechanical Behavior of 17-4 Precipitation Hardenable Steel Processed by Selective Laser Melting  

NASA Astrophysics Data System (ADS)

The mechanical behavior and the microstructural evolution of 17-4 precipitation hardenable (PH) stainless steel processed using selective laser melting have been studied. Test coupons were produced from 17-4 PH stainless steel powder in argon and nitrogen atmospheres. Characterization studies were carried out using mechanical testing, optical microscopy, scanning electron microscopy, and x-ray diffraction. The results show that post-process heat treatment is required to obtain typically desired tensile properties. Columnar grains of smaller diameters (<2 µm) emerged within the melt pool with a mixture of martensite and retained austenite phases. It was found that the phase content of the samples is greatly influenced by the powder chemistry, processing environment, and grain diameter.

Rafi, H. Khalid; Pal, Deepankar; Patil, Nachiket; Starr, Thomas L.; Stucker, Brent E.

2014-12-01

394

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

NASA Astrophysics Data System (ADS)

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.

Hajihashemi, Mahdi; Niroumand, Behzad; Shamanian, Morteza

2014-12-01

395

Thermal Replication Trap  

NASA Astrophysics Data System (ADS)

The hallmark of living matter is the replication of genetic molecules and their active storage against diffusion. We have argued in the past that thermal convection can host the million-fold accumulation even of single nucleotides and at the same time trigger exponential replication [1]. Accumulation is driven by thermophoresis and convection in elongated chambers, replication by the inherent temperature cycling in convection. Optothermal pumping [2,3] allows to implement the thermal trap efficiently in a toroidal [4] or linear [5] geometry. Based on this method, we were in a position to combine accumulation and replication of DNA in the same chamber [5]. As we are missing a solid chemistry of prebiotic replication, we used as a proxy reaction for to replication the polymerase chain reaction. Convective flow both drives the DNA replicating polymerase chain reaction (PCR) while concurrent thermophoresis accumulates the replicated 143 base pair DNA in bulk solution. The time constant for accumulation is 92 s while DNA is doubled every 50 s. The length of the amplified DNA is checked with thermophoresis. Finite element simulations confirm the findings. The experiments explore conditions in pores of hydrothermal rock which can serve as a model environment for the origin of life and has prospects towards the first autonomous evolution, hosting the Darwin process by molecular selection using the thermophoretic trap. On the other side, the implemented continuous evolution will be able to breed well specified DNA or RNA molecules in the future. [4pt] [1] Baaske, Weinert, Duhr, Lemke, Russell and Braun, PNAS 104, 9346 (2007) [0pt] [2] Weinert, Kraus, Franosch and Braun, PRL 100, 164501 (2008) [0pt] [3] Weinert and Braun, Journal of Applied Physics 104, 104701 (2008) [0pt] [4] Weinert and Braun, Nano Letters 9, 4264 (2009) [0pt] [5] Mast and Braun, PRL 104, 188102 (2010)

Braun, Dieter

2011-03-01

396

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

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.

N.N. Gorelenkov; A. Gondhalekar; A.A. Korotkov; S.E. Sharapov; D. Testa; and Contributors to the EFDA-JET Workprogramme

2002-01-18

397

The Canadian Penning Trap mass spectrometer  

NASA Astrophysics Data System (ADS)

The Canadian Penning Trap (CPT) mass spectrometer located at the ATLAS facility of Argonne National Laboratory is an online Penning trap system used for mass measurements of high accuracy on short-lived isotopes. It uses a gas catcher as a novel way to transform radioactive ions efficiently from different sources into cooled beams which are injected into ion traps for further preparation and measurement. The CPT has recently been successfully used to make precise mass measurements on over 40 neutron-rich and neutron-deficient radioactive nuclides related to astrophysical processes.

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

2004-12-01

398

Imaging single-cell signaling dynamics with a deterministic high-density single-cell trap array  

PubMed Central

Stochasticity in gene expression, protein or metabolite levels contributes to cell-cell variations, the analysis of which could lead to a better understanding of cellular processes and drug responses. Current technologies are limited in their throughput, resolution (in space, time, and tracking individual cells instead of population average) and the ability to control cellular environment. A few microfluidic tools have been developed to trap and image cells; however, in most designs available to date, there is a compromise among loading efficiency, speed, the ability to trap single cells, and density or number of trapped cells. To meet the needs of single-cell imaging studies, we developed a microfluidic platform for high-throughput capture and imaging of thousands of single cells. The optimized trapping mechanism enables 95% of the traps to be occupied with single cells, with a trap density of 860 traps / mm2. The dense array allows up to 800 cells to be imaged simultaneously with a 4× objective and a typical camera setup. Capture occurs with low shear and 94% viability after 24h. This platform is compatible with other upstream microfluidic components for complex cell stimulation patterns, and we show here the ability to measure heterogeneity in calcium oscillatory behavior in genetically identical cells and monitor kinetic cellular response to chemical stimuli. PMID:21809821

Chung, Kwanghun; Rivet, Catherine A.; Kemp, Melissa L.; Lu, Hang

2011-01-01

399

Modular cryostat for ion trapping with surface-electrode ion traps  

NASA Astrophysics Data System (ADS)

We present a simple cryostat purpose built for use with surface-electrode ion traps, designed around an affordable, large cooling power commercial pulse tube refrigerator. A modular vacuum enclosure with a single vacuum space facilitates interior access and enables rapid turnaround and flexibility for future modifications. Long rectangular windows provide nearly 360° of optical access in the plane of the ion trap, while a circular bottom window near the trap enables NA 0.4 light collection without the need for in-vacuum optics. We evaluate the system's mechanical and thermal characteristics and we quantify ion trapping performance by trapping 40Ca+, finding small stray electric fields, long ion lifetimes, and low ion heating rates.

Vittorini, Grahame; Wright, Kenneth; Brown, Kenneth R.; Harter, Alexa W.; Doret, S. Charles

2013-04-01

400

Modular cryostat for ion trapping with surface-electrode ion traps.  

PubMed

We present a simple cryostat purpose built for use with surface-electrode ion traps, designed around an affordable, large cooling power commercial pulse tube refrigerator. A modular vacuum enclosure with a single vacuum space facilitates interior access and enables rapid turnaround and flexibility for future modifications. Long rectangular windows provide nearly 360° of optical access in the plane of the ion trap, while a circular bottom window near the trap enables NA 0.4 light collection without the need for in-vacuum optics. We evaluate the system's mechanical and thermal characteristics and we quantify ion trapping performance by trapping (40)Ca(+), finding small stray electric fields, long ion lifetimes, and low ion heating rates. PMID:23635186

Vittorini, Grahame; Wright, Kenneth; Brown, Kenneth R; Harter, Alexa W; Doret, S Charles

2013-04-01

401

Bicoherence analysis of streamer dynamics induced by trapped ion modes  

NASA Astrophysics Data System (ADS)

High order spectral analyses have recently attracted a great deal of attention in the context of experimental studies for magnetic fusion. Among these techniques, bicoherence analysis plays an important role as it allows distinguishing between spontaneously excited waves and waves that arise from a coupling between different modes linked to specific physical mechanisms. Here, we describe and apply bicoherence analysis to kinetic simulations performed with reduced "bounce-averaged gyrokinetic" code, in order to investigate the nonlinear dynamics of trapped ion modes. This analysis shows a nonlinear wave coupling process linked to the formation of convective cells, thus furthers our understanding of the nonlinear energy transfer between turbulence structures in tokamaks.

Palermo, Francesco; Garbet, Xavier; Ghizzo, Alain

2015-01-01

402

Photodynamic action of actinomycin D: an EPR spin trapping study.  

PubMed

Actinomycin D is one of the most widely studied anticancer antibiotic that binds to both double-stranded and single-stranded DNA, and this binding greatly enhances the DNA photosensitization. By use of electron paramagnetic resonance spin trapping techniques, both superoxide radical anion and the radical anion of actinomycin D were identified as important intermediates in the photodynamic process. A mechanism of electron transfer from a DNA base to excited actinomycin D was proposed. These novel findings may shed new light on future application of this drug in photodynamic therapy or cleavage of DNA in unique and controllable ways. PMID:11420136

Pan, J X; Liu, Y; Zhang, S P; Tu, T C; Yao, S D; Lin, N Y

2001-07-01

403

Mechanical Properties and Microstructure of AZ31B Magnesium Alloy Processed by I-ECAP  

NASA Astrophysics Data System (ADS)

Incremental equal channel angular pressing (I-ECAP) is a severe plastic deformation process used to refine grain size of metals, which allows processing very long billets. As described in the current article, an AZ31B magnesium alloy was processed for the first time by three different routes of I-ECAP, namely, A, BC, and C, at 523 K (250 °C). The structure of the material was homogenized and refined to ~5 microns of the average grain size, irrespective of the route used. Mechanical properties of the I-ECAPed samples in tension and compression were investigated. Strong influence of the processing route on yield and fracture behavior of the material was established. It was found that texture controls the mechanical properties of AZ31B magnesium alloy subjected to I-ECAP. SEM and OM techniques were used to obtain microstructural images of the I-ECAPed samples subjected to tension and compression. Increased ductility after I-ECAP was attributed to twinning suppression and facilitation of slip on basal plane. Shear bands were revealed in the samples processed by I-ECAP and subjected to tension. Tension-compression yield stress asymmetry in the samples tested along extrusion direction was suppressed in the material processed by routes BC and C. This effect was attributed to textural development and microstructural homogenization. Twinning activities in fine- and coarse-grained samples have also been studied.

Gzyl, Michal; Rosochowski, Andrzej; Pesci, Raphael; Olejnik, Lech; Yakushina, Evgenia; Wood, Paul

2013-11-01

404

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

NASA Astrophysics Data System (ADS)

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).

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

2011-02-01

405

TRAP1 revisited: novel localizations and functions of a 'next-generation' biomarker (review).  

PubMed

In the last decade, the identification and characterization of novel molecular mechanisms and pathways involving the heat shock protein TRAP1/HSP75 in cancers and other diseases enhanced the scientific interest. Recent reports have shown that TRAP1 stays at the crossroad of multiple crucial processes in the onset of neoplastic transformation. In fact, TRAP1: i) contributes to the tumor's switch to aerobic glycolysis through the inhibition of succinate dehydrogenase, the complex II of the mitochondrial respiratory chain; ii) is part of a pro-survival signaling pathway aimed at evading the toxic effects of oxidants and anticancer drugs and protects mitochondria against damaging stimuli via a decrease of ROS generation; iii) controls protein homeostasis through a direct involvement in the regulation of protein synthesis and protein co-translational degradation. Therefore, TRAP1 seems to be a central regulatory protein with balancing functions at the intersection of different metabolic processes during the neoplastic transformation. For this reason, it can be considered at the same time an attractive target for the development of novel anticancer strategies and a promising study model to understand the biology of tumor cells at a systemic level. This review summarizes the most recent advances in TRAP1 biology and proposes a new comprehensive view of its functions. PMID:24990602

Amoroso, Maria Rosaria; Matassa, Danilo Swann; Sisinni, Lorenza; Lettini, Giacomo; Landriscina, Matteo; Esposito, Franca

2014-09-01

406

Trapped Electron Precession Shear Induced Fluctuation Decorrelation  

SciTech Connect

We consider the effects of trapped electron precession shear on the microturbulence. In a similar way the strong E x B shear reduces the radial correlation length of ambient fluctuations, the radial variation of the trapped electron precession frequency can reduce the radial correlation length of fluctuations associated with trapped electrons. In reversed shear plasmas, with the explicit dependence of the trapped electron precession shearing rate on B(subscript)theta, the sharp radial gradient of T(subscript)e due to local electron heating inside qmin can make the precession shearing mechanism more effective, and reduce the electron thermal transport constructing a positive feedback loop for the T(subscript)e barrier formation.

T.S. Hahm; P.H. Diamond; E.-J. Kim

2002-07-29

407

Steam Trap Management  

E-print Network

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...

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

408

Diesel particulate traps  

Microsoft Academic Search

For use with a diesel engine having at least one exhaust bank, a particulate trap system is described comprising: an exhaust conduit ducting exhaust materials firstly through an exhaust cooler, thence to a diesel particulate trap, thence to the atmosphere, a by-pass conduit connected in parallel with the exhaust cooler between a first location upstream of the cooler and a

Burlington

1987-01-01

409

The magnetism of a glacial aeolianite sequence from Lanzarote (Canary Islands): coupling between luvic calcisol formation and Saharan dust trapping processes during wet deposition events off northwestern Sahara  

NASA Astrophysics Data System (ADS)

In order to better document the climatic origin of pedogenized loess deposits west of Sahara, rock-magnetic measurements were performed on a Last Glacial coastal sand sequence from La Mala (LM) quarry (Lanzarote, Canary Islands) containing six interbedded loess-palaeosol units. Hysteresis and susceptibility data point to a coarse-grained magnetic enhancement in the coastal sand, which contrasts with the superparamagnetic (SP) to pseudo-single domain (PSD) behaviour of the Saharan loess and palaeosol. High- and low-temperature experiments show that oxidized titanomagnetite contributions dominate in the sand, while fine-grained (SP to PSD) iron oxidation products such as maghemite and goethite are evidenced in the Saharan loess/palaeosol units. At room temperature, the detrital PSD-multidomain titanomagnetite contribution of local origin is tentatively estimated from the AC-field dependence of magnetic susceptibility. Surface oxidation of detrital spinel grains and authigenesis of fine-grained iron oxides (including SP goethite) are proposed to explain the magnetic properties of the primarily fine, Saharan-dust-bearing material. The dry, local climate of the present-day and Late Holocene means that loess deposits are not preserved. The six pedogenized loess units, however, point to dust trapping under semi-arid, wetter conditions, probably illustrating periods of reduced latitudinal temperature gradients and climate variability of the North Atlantic climate, respectively. These findings suggest that both the Canary palaeosol and its content of (ultra)fine iron oxide might be constrained by (wet) deposition and trapping of fine Saharan dust.

Williamson, David; Jackson, Mike; Banerjee, Subir K.; Petit-Maire, Nicole

2004-06-01

410

Optical Trapping of Nanoparticles  

PubMed Central

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping and manipulating small biological particles. Ashkin and co-workers first demonstrated optical tweezers using a single focused beam1. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles1. In the perturbative regime, the optical power required for trapping a particle scales as the inverse fourth power of the particle size. High optical powers can damage dielectric particles and cause heating. For instance, trapped latex spheres of 109 nm in diameter were destroyed by a 15 mW beam in 25 sec1, which has serious implications for biological matter2,3. A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime4. In a non-perturbative regime, even a small particle with little permittivity contrast to the background can influence significantly the ambient electromagnetic field and induce a large optical force. As a particle enters an illuminated aperture, light transmission increases dramatically because of dielectric loading. If the particle attempts to leave the aperture, decreased transmission causes a change in momentum outwards from the hole and, by Newton's Third Law, results in a force on the particle inwards into the hole, trapping the particle. The light transmission can be monitored; hence, the trap can become a sensor. The SIBA trapping technique can be further improved by using a double-nanohole structure. The double-nanohole structure has been shown to give a strong local field enhancement5,6. Between the two sharp tips of the double-nanohole, a small particle can cause a large change in optical transmission, thereby inducing a large optical force. As a result, smaller nanoparticles can be trapped, such as 12 nm silicate spheres7 and 3.4 nm hydrodynamic radius bovine serum albumin proteins8. In this work, the experimental configuration used for nanoparticle trapping is outlined. First, we detail the assembly of the trapping setup which is based on a Thorlabs Optical Tweezer Kit. Next, we explain the nanofabrication procedure of the double-nanohole in a metal film, the fabrication of the microfluidic chamber and the sample preparation. Finally, we detail the data acquisition procedure and provide typical results for trapping 20 nm polystyrene nanospheres. PMID:23354173

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

2013-01-01

411

Optical trapping of dielectric nanoparticles in resonant cavities  

SciTech Connect

We theoretically investigate the opto-mechanical interactions between a dielectric nanoparticle and the resonantly enhanced optical field inside a high Q, small-mode-volume optical cavity. We develop an analytical method based on open system analysis to account for the resonant perturbation due to particle introduction and predict trapping potential in good agreement with three-dimensional (3D) finite-difference time-domain (FDTD) numerical simulations. Strong size-dependent trapping dynamics distinctly different from free-space optical tweezers arise as a consequence of the finite cavity perturbation. We illustrate single nanoparticle trapping from an ensemble of monodispersed particles based on size-dependent trapping dynamics. We further discover that the failure of the conventional dipole approximation in the case of resonant cavity trapping originates from a new perturbation interaction mechanism between trapped particles and spatially localized photons.

Hu Juejun [Microphotonics Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716 (United States); Lin Shiyun; Crozier, Kenneth [School of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts 02138 (United States); Kimerling, Lionel C. [Microphotonics Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2010-11-15

412

The use (and misuse) of sediment traps in coral reef environments: theory, observations, and suggested protocols  

NASA Astrophysics Data System (ADS)

Sediment traps are commonly used as standard tools for monitoring "sedimentation" in coral reef environments. In much of the literature where sediment traps were used to measure the effects of "sedimentation" on corals, it is clear from deployment descriptions and interpretations of the resulting data that information derived from sediment traps has frequently been misinterpreted or misapplied. Despite their widespread use in this setting, sediment traps do not provide quantitative information about "sedimentation" on coral surfaces. Traps can provide useful information about the relative magnitude of sediment dynamics if trap deployment standards are used. This conclusion is based first on a brief review of the state of knowledge of sediment trap dynamics, which has primarily focused on traps deployed high above the seabed in relatively deep water, followed by our understanding of near-bed sediment dynamics in shallow-water environments that characterize coral reefs. This overview is followed by the first synthesis of near-bed sediment trap data collected with concurrent hydrodynamic information in coral reef environments. This collective information is utilized to develop nine protocols for using sediment traps in coral reef environments, which focus on trap parameters that researchers can control such as trap height ( H), trap mouth diameter ( D), the height of the trap mouth above the substrate ( z o ), and the spacing between traps. The hydrodynamic behavior of sediment traps and the limitations of data derived from these traps should be forefront when interpreting sediment trap data to infer sediment transport processes in coral reef environments.

Storlazzi, C. D.; Field, M. E.; Bothner, M. H.

2011-03-01

413

Optically programmable excitonic traps.  

PubMed

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

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

2013-01-01

414

Nonlinear integrable ion traps  

SciTech Connect

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

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

2011-10-01

415

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

PubMed Central

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

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

2012-01-01

416

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

SciTech Connect

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.

Tsang, C.F.; Mangold, D.C. (eds.)

1984-07-01

417

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

SciTech Connect

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.

Kolarik, Robert V.

2005-11-11

418

Mechanical properties and production quality of hand-layup and vacuum infusion processed hybrid composite materials for GFRP marine structures  

NASA Astrophysics Data System (ADS)

Glass Fiber Reinforced Plastic (GFRP) structures are primarily manufactured using hand lay-up or vacuum infusion techniques, which are cost-effective for the construction of marine vessels. This paper aims to investigate the mechanical properties and failure mechanisms of the hybrid GFRP composites, formed by applying the hand lay-up processed exterior and the vacuum infusion processed interior layups, providing benefits for structural performance and ease of manufacturing. The hybrid GFRP composites contain one, two, and three vacuum infusion processed layer sets with consistent sets of hand lay-up processed layers. Mechanical properties assessed in this study include tensile, compressive and in-plane shear properties. Hybrid composites with three sets of vacuum infusion layers showed the highest tensile mechanical properties while those with two sets had the highest mechanical properties in compression. The batch homogeneity, for the GFRP fabrication processes, is evaluated using the experimentally obtained mechanical properties

Kim, Sang-Young; Shim, Chun Sik; Sturtevant, Caleb; Kim, Dave (Dae-Wook); Song, Ha Cheol

2014-09-01

419

Vacancy trapping mechanism for hydrogen bubble formation in metal Yue-Lin Liu, Ying Zhang, Hong-Bo Zhou, and Guang-Hong Lu*  

E-print Network

is one of the most important topics in materials physics, having a broad range of technological embrittle- ment in metals.4 Furthermore, in a fusion reactor, metals are used as the plasma facing material for degrading mechanical properties of metals.5 H has been shown to assist vacancy formation in various metals

Liu, Feng

420

Switching mechanisms in flexible solution-processed TiO? memristors.  

PubMed

Memristors are emerging as unique electrical devices with potential applications in memory, reconfigurable logic and biologically inspired computing. Due to the novelty of these devices, the complete details of their switching mechanism is not yet well established. In this work, the switching mechanism of our solution-processed titanium dioxide-based memristor is investigated by studying how variations in the device area and film thickness affect electrical behavior and correlating these behavioral changes to proposed switching mechanisms. The conduction path of the switching is also investigated through electrical characterization of devices both before and after physically cutting the devices in half, as well as through infrared imaging of the devices during operation. The results suggest that the electrical behavior of these devices is dominated by a localized, charge-based phenomenon that exhibits a dependence on device area. PMID:22780990

Tedesco, J L; Stephey, L; Hernández-Mora, M; Richter, C A; Gergel-Hackett, N

2012-08-01

421

DNA repair. Mechanism of DNA interstrand cross-link processing by repair nuclease FAN1.  

PubMed

DNA interstrand cross-links (ICLs) are highly toxic lesions associated with cancer and degenerative diseases. ICLs can be repaired by the Fanconi anemia (FA) pathway and through FA-independent processes involving the FAN1 nuclease. In this work, FAN1-DNA crystal structures and biochemical data reveal that human FAN1 cleaves DNA successively at every third nucleotide. In vitro, this exonuclease mechanism allows FAN1 to excise an ICL from one strand through flanking incisions. DNA access requires a 5'-terminal phosphate anchor at a nick or a 1- or 2-nucleotide flap and is augmented by a 3' flap, suggesting that FAN1 action is coupled to DNA synthesis or recombination. FAN1's mechanism of ICL excision is well suited for processing other localized DNA adducts as well. PMID:25430771

Wang, Renjing; Persky, Nicole S; Yoo, Barney; Ouerfelli, Ouathek; Smogorzewska, Agata; Elledge, Stephen J; Pavletich, Nikola P

2014-11-28

422

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

PubMed

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

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

2015-01-01

423

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

PubMed Central

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

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

2015-01-01

424

The role of cavitation effects in the mechanisms of destruction and explosive processes  

NASA Astrophysics Data System (ADS)

The paper presents a review of the experimental results, mathematical models and numerical investigations of wave processes and the dynamics of liquid media under impulse loading. The presence of micro-inhomogeneities can change substantially the state of the liquid, the structure of the applied wave field and the mechanisms of the physical processes that take place in the liquid. Some crucial research trends received proper attention: the cavitation fracture of liquid under explosive loading, different methods of describing the mechanisms of pressurized-liquid tank explosions, the effects of bubble cavitation and inhomogeneities on the sensitivity of high explosives (HE) to the initiation and propagation of detonation, the problem of focusing the shock waves, and destruction of stones in lithotriptors.

Kredrinskii, V. K.

425

Thermo-hydro-mechanical-chemical processes in fractured-porous media: Benchmarks and examples  

NASA Astrophysics Data System (ADS)

The book comprises an assembly of benchmarks and examples for porous media mechanics collected over the last twenty years. Analysis of thermo-hydro-mechanical-chemical (THMC) processes is essential to many applications in environmental engineering, such as geological waste deposition, geothermal energy utilisation, carbon capture and storage, water resources management, hydrology, even climate change. In order to assess the feasibility as well as the safety of geotechnical applications, process-based modelling is the only tool to put numbers, i.e. to quantify future scenarios. This charges a huge responsibility concerning the reliability of computational tools. Benchmarking is an appropriate methodology to verify the quality of modelling tools based on best practices. Moreover, benchmarking and code comparison foster community efforts. The benchmark book is part of the OpenGeoSys initiative - an open source project to share knowledge and experience in environmental analysis and scientific computation.

Kolditz, O.; Shao, H.; Görke, U.; Kalbacher, T.; Bauer, S.; McDermott, C. I.; Wang, W.

2012-12-01

426

Surface trap for ytterbium ions  

E-print Network

We conducted an experiment to load a shallow planar ion trap from a cold atom source of Ytterbium using photoionization. The surface trap consisted of a three-rod radio frequency Paul trap fabricated using standard printed ...

Campbell, Jonathan A. (Jonathan Alan)

2006-01-01

427

Improvement of mechanical properties of aluminum die casting alloy by multi-pass friction stir processing  

Microsoft Academic Search

An improvement in the mechanical properties was accomplished due to the microstructural modification of an aluminum die casting alloy by multi-pass friction stir processing (MP-FSP), which is a solid-state microstructural modification technique using a frictional heat and stirring action. The hardness of the MP-FSP sample is about 20Hv higher than that of the base metal. The tensile strengths of the

K. Nakata; Y. G. Kim; H. Fujii; T. Tsumura; T. Komazaki

2006-01-01

428

Microstructure and mechanical properties of AZ80 magnesium alloy sheet processed by differential speed rolling  

Microsoft Academic Search

A heat-treatable AZ80 magnesium alloy has been subjected to differential speed rolling (DSR) at a large thickness reduction per pass of 33%, and microstructure, texture, mechanical properties, stretch formability as well as texture evolution during stretch forming have been investigated. The basal pole of the DSR-processed sheet tilts toward the rolling direction at 15°. The as-rolled sheet exhibits a combination

Xinsheng Huang; Kazutaka Suzuki; Naobumi Saito

2009-01-01

429

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

NASA Technical Reports Server (NTRS)

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.

Przewlocka, H.; Siedlecka, J.

1982-01-01

430

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

SciTech Connect

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.

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

431

Prevalent and distinct spliceosomal 3'-end processing mechanisms for fungal telomerase RNA.  

PubMed

Telomerase RNA (TER) is an essential component of the telomerase ribonucleoprotein complex. The mechanism for TER 3'-end processing is highly divergent among different organisms. Here we report a unique spliceosome-mediated TER 3'-end cleavage mechanism in Neurospora crassa that is distinct from that found specifically in the fission yeast Schizosaccharomyces pombe. While the S. pombe TER intron contains the canonical 5'-splice site GUAUGU, the N. crassa TER intron contains a non-canonical 5'-splice site AUAAGU that alone prevents the second step of splicing and promotes spliceosomal cleavage. The unique N. crassa TER 5'-splice site sequence is evolutionarily conserved in TERs from Pezizomycotina and early branching Taphrinomycotina species. This suggests that the widespread and basal N. crassa-type spliceosomal cleavage mechanism is more ancestral than the S. pombe-type. The discovery of a prevalent, yet distinct, spliceosomal cleavage mechanism throughout diverse fungal clades furthers our understanding of TER evolution and non-coding RNA processing. PMID:25598218

Qi, Xiaodong; Rand, Dustin P; Podlevsky, Joshua D; Li, Yang; Mosig, Axel; Stadler, Peter F; Chen, Julian J-L

2015-01-01

432

Inertial measurement with trapped particles: A microdynamical system  

SciTech Connect

We describe an inertial measurement device based on an electrodynamically trapped proof mass. Mechanical constraints are replaced by guiding fields, permitting the trap stiffness to be tuned dynamically. Optical readout of the proof mass motion provides a measurement of acceleration and rotation, resulting in an integrated six degree of freedom inertial measurement device. We demonstrate such a device - constructed without microfabrication - with sensitivity comparable to that of commercial microelectromechanical systems technology and show how trapping parameters may be adjusted to increase dynamic range.

Post, E. Rehmi; Popescu, George A.; Gershenfeld, Neil [Center for Bits and Atoms, Massachusetts Institute of Technology, 20 Ames Street, Cambridge, Massachusetts 02139 (United States)

2010-04-05

433

Kinetics of physico-chemical processes during intensive mechanical processing of ZnO-MnO 2 powder mixture  

NASA Astrophysics Data System (ADS)

Experimental results of electron paramagnetic resonance spectra, X-ray diffraction, scanning electron microscopy and infrared spectroscopy demonstrate that the kinetic of the physical and chemical processes that takes place during prolonged intensive mechanical processing (MP, 03120 min) of powder mixtures of 50%wt ZnO+50%wt MnO 2 can be described as a three stage process. (1) 030 min, particles destruction, formation of superficial defects, fast increment of sample average temperature (from 290 to ˜600 K) and annealing of defects with the lowest energy of activation Eac. (2) 30390 min, further particle destruction, slow increment of sample average temperature (from ˜600 to ˜700 K), formation and growth of a very disordered layer of ?-MnO2 around ZnO particles, dehydration of MnO 2, formation of solid solution of Mn 2+ ions in ZnO, formation of nano-quasiamorphous states in the ZnO-MnO 2 mixture and onset of the formation of the ZnMnO 3 phase. (3) 3903120 min, the sample average temperature remains constant ( ˜700 K), the reaction is completed and the spinel ZnMnO 3 phase with a unit cell a=8.431(1) Å and space group Fd3¯m is the only phase present in the sample. No ferromagnetism at room temperature was detected in this study.

Kakazey, M.; Vlasova, M.; Dominguez-Patiño, M.; Juarez-Arellano, E. A.; Bykov, A.; Leon, I.; Siqueiros-Diaz, A.

2011-10-01

434

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

435

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

PubMed

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

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

2010-05-15

436

The Effects of Processing Methods upon Mechanical and Biologic Properties of Porcine Dermal Extracellular Matrix Scaffolds  

PubMed Central

Biologic materials from various species and tissues are commonly used as surgical meshes or scaffolds for tissue reconstruction. Extracellular matrix (ECM) represents the secreted product of the cells comprising each tissue and organ, and therefore provides a unique biologic material for selected regenerative medicine applications. Minimal disruption of ECM ultrastructure and content during tissue processing is typically desirable. The objective of this study was to systematically evaluate effects of commonly used tissue processing steps upon porcine dermal ECM scaffold composition, mechanical properties, and cytocompatibility. Processing steps evaluated included liming and hot water sanitation, trypsin/SDS/TritonX-100 decellularization, and trypsin/TritonX-100 decellularization. Liming decreased the growth factor and glycosaminoglycan content, the mechanical strength, and the ability of the ECM to support in vitro cell growth (p ? 0.05 for all). Hot water sanitation treatment decreased only the growth factor content of the ECM (p ? 0.05). Trypsin/SDS/TritonX-100 decellularization decreased the growth factor content and the ability of the ECM to support in vitro cell growth (p ? 0.05 for both). Trypsin/TritonX-100 decellularization also decreased the growth factor content of the ECM but increased the ability of the ECM to support in vitro cell growth (p ? 0.05 for both). We conclude that processing steps evaluated in the present study affect content, mechanical strength, and/or cytocompatibility of the resultant porcine dermal ECM, and therefore care must be taken in choosing appropriate processing steps to maintain the beneficial effects of ECM in biologic scaffolds. PMID:20728934

Reing, Janet E.; Brown, Bryan N.; Daly, Kerry A.; Freund, John M.; Gilbert, Thomas W.; Hsiong, Susan; Huber, Alexander; Kullas, Karen E.; Tottey, Stephen; Wolf, Matthew; Badylak, Stephen F.

2010-01-01

437

Kinetic mechanism of Nicotiana tabacum myosin-11 defines a new type of a processive motor.  

PubMed

The 175-kDa myosin-11 from Nicotiana tabacum (Nt(175kDa)myosin-11) is exceptional in its mechanical activity as it is the fastest known processive actin-based motor, moving 10 times faster than the structurally related class 5 myosins. Although this ability might be essential for long-range organelle transport within larger plant cells, the kinetic features underlying the fast processive movement of Nt(175kDa)myosin-11 still remain unexplored. To address this, we generated a single-headed motor domain construct and carried out a detailed kinetic analysis. The data demonstrate that Nt(175kDa)myosin-11 is a highduty ratio motor, which remains associated with actin most of its enzymatic cycle. However, different from other processive myosins that establish a high duty ratio on the basis of a rate-limiting ADP-release step, Nt(175kDa)myosin-11 achieves a high duty ratio by a prolonged duration of the ATP-induced isomerization of the actin-bound states and ADP release kinetics, both of which in terms of the corresponding time constants approach the total ATPase cycle time. Molecular modeling predicts that variations in the charge distribution of the actin binding interface might contribute to the thermodynamic fine-tuning of the kinetics of this myosin. Our study unravels a new type of a high duty ratio motor and provides important insights into the molecular mechanism of processive movement of higher plant myosins.-Diensthuber, R. P., Tominaga, M., Preller, M., Hartmann, F. K., Orii, H., Chizhov, I., Oiwa, K., Tsiavaliaris, G. Kinetic mechanism of Nicotiana tabacum myosin-11 defines a new type of a processive motor. PMID:25326536

Diensthuber, Ralph P; Tominaga, Motoki; Preller, Matthias; Hartmann, Falk K; Orii, Hidefumi; Chizhov, Igor; Oiwa, Kazuhiro; Tsiavaliaris, Georgios

2015-01-01

438

The nature of the TRAP-Anti-TRAP complex.  

PubMed

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

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

2009-02-17

439

Evaluation of a Post-Processing Approach for Multiscale Analysis of Biphasic Mechanics of Chondrocytes  

PubMed Central

Understanding the mechanical behavior of chondrocytes as a result of cartilage tissue mechanics has significant implications for both evaluation of mechanobiological function and to elaborate on damage mechanisms. A common procedure for prediction of chondrocyte mechanics (and of cell mechanics in general) relies on a computational post-processing approach where tissue level deformations drive cell level models. Potential loss of information in this numerical coupling approach may cause erroneous cellular scale results, particularly during multiphysics analysis of cartilage. The goal of this study was to evaluate the capacity of 1st and 2nd order data passing to predict chondrocyte mechanics by analyzing cartilage deformations obtained for varying complexity of loading scenarios. A tissue scale model with a sub-region incorporating representation of chondron size and distribution served as control. The postprocessing approach first required solution of a homogeneous tissue level model, results of which were used to drive a separate cell level model (same characteristics as the subregion of control model). The 1st data passing appeared to be adequate for simplified loading of the cartilage and for a subset of cell deformation metrics, e.g., change in aspect ratio. The 2nd order data passing scheme was more accurate, particularly when asymmetric permeability of the tissue boundaries were considered. Yet, the method exhibited limitations for predictions of instantaneous metrics related to the fluid phase, e.g., mass exchange rate. Nonetheless, employing higher-order data exchange schemes may be necessary to understand the biphasic mechanics of cells under lifelike tissue loading states for the whole time history of the simulation. PMID:23809004

Sibole, Scott C.; Maas, Steve; Halloran, Jason P.; Weiss, Jeffrey A.; Erdemir, Ahmet

2014-01-01

440

The charge-trapping and triplet-triplet annihilation processes in organic light-emitting diodes: A duty cycle dependence study on magneto-electroluminescence  

NASA Astrophysics Data System (ADS)

We studied the magneto-electroluminescence (MEL) in tri-(8-hydroxyquinoline)-aluminum (Alq3)-based organic light-emitting devices through both steady-state and transient methods. As the magnetic field increases, the MEL exhibits a rapid rise, followed by the saturation tendency at all voltages in the steady-state measurement, but in the transient measurement it first increases to a maximum and then decreases to negative values when the driving voltages are higher than 8V. Furthermore, we found that the MEL strongly depends on the duty cycle of the pulse voltage. Finally, by employing the triplet-triplet annihilation model combined with the charge trapping effects, we explained the duty cycle dependence of MELs.

Peng, Qiming; Chen, Ping; Li, Feng

2013-01-01