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1

Physical mechanisms in double-carrier trap-charge limited transport processes in organic electroluminescent devices: A numerical study  

NASA Astrophysics Data System (ADS)

We have developed a numerical model to simulate the double-carrier injection trap-charge limited (TCL) transport processes in organic electroluminescent devices (OEDs). Current-voltage characteristics, energy and charge profiles are obtained and analyzed to understand the mechanisms governing the OED performance under TCL conditions. Good agreement with general experimental trends and previous analytical predictions are achieved. Dependencies on several important parameters (carrier injection level, device thickness, recombination constant, temperature, etc.) are also studied.

Shen, Jun; Yang, Jie

1998-06-01

2

Trapped Atomic Ions and Quantum Information Processing  

SciTech Connect

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

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

2006-11-07

3

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

SciTech Connect

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

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

2014-08-14

4

Physical process Mechanical mechanisms  

E-print Network

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

Berlin,Technische Universität

5

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

NASA Astrophysics Data System (ADS)

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

Kim, Yeong E.; Zubarev, Alexander L.

2006-02-01

6

Kinetics and mechanism of Dionaea muscipula trap closing.  

PubMed

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

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

2008-02-01

7

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

PubMed Central

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

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

2012-01-01

8

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

9

Reactive Transport Modelling of CO2 Storage in Saline Aquifers to Elucidate Fundamental Processes, Trapping Mechanisms, and Sequestration Partitioning  

Microsoft Academic Search

The ultimate fate of CO injected into saline aquifers for environmental isolation is governed by three interdependent yet conceptually distinct processes: CO migration as a buoyant immiscible fluid phase, direct chemical interaction of this rising plume with ambient saline waters, and its indirect chemical interaction with aquifer and cap-rock minerals through the aqueous wetting phase. Each process is directly linked

J. W. Johnson; J. J. Nitao; K. G. Knauss

2004-01-01

10

Continuous regeneration of an electrically heated diesel particulate trap: Mechanism of particulate matter trapping and improvement of trapping efficiency  

Microsoft Academic Search

The mechanisms of trapping and continuous regeneration of soot particles in a newly developed diesel particulate trap based on static-electric trapping (electrical diesel particulate trap, E-DPT) are investigated. It is found from a visualization experiment that soot particles trapped on the electro-plates form soot bridges over the 1.5 mm narrow space between the electro-plates and burn out by Joule's heating,

M Saito; H Hoshino; T Furuhata; M Arai

2010-01-01

11

Relativistic quantum mechanics with trapped ions  

NASA Astrophysics Data System (ADS)

We consider the quantum simulation of relativistic quantum mechanics, as described by the Dirac equation and classical potentials, in trapped-ion systems. We concentrate on three problems of growing complexity. Firstly, we study the bidimensional relativistic scattering of single Dirac particles by a linear potential. Secondly, we explore the case of a Dirac particle in a magnetic field and its topological properties. Finally, we analyze the problem of two Dirac particles that are coupled by a controllable and confining potential. The latter interaction may be useful to study important phenomena such as the confinement and asymptotic freedom of quarks.

Lamata, L.; Casanova, J.; Gerritsma, R.; Roos, C. F.; Garca-Ripoll, J. J.; Solano, E.

2011-09-01

12

Quantum information processing with trapped ions  

E-print Network

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

Hensinger, Winfried

13

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

14

Mechanisms for mechanical trapping of geologically sequestered carbon dioxide  

PubMed Central

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

Cohen, Yossi; Rothman, Daniel H.

2015-01-01

15

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

E-print Network

Spontaneous Firings of Carnivorous Aquatic Utricularia Traps: Temporal Patterns and Mechanical are carnivorous plants living in environments poor in nutrients. Their trapping mechanism has fascinated) Spontaneous Firings of Carnivorous Aquatic Utricularia Traps: Temporal Patterns and Mechanical Oscillations

Paris-Sud XI, Université de

16

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

17

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

2008-05-19

18

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

Microsoft Academic Search

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

Yeong E. Kim; Alexander L. Zubarev

2006-01-01

19

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

Microsoft Academic Search

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

Yeong E. Kim; Alexander L. Zubarev

20

Statistical Mechanics of a Trapped Bose-Einstein Condensate  

E-print Network

Bose-Einstein condensation (BEC) in a gas has now been achieved. Alkali atoms ($^{87}Rb$, $^{23}Na$ and $^{7}Li$) have been cooled to the point of condensation (temperature of 100 nK) using laser cooling and trapping, followed by magnetic trapping and evaporative cooling. This important experimental result has also renewed the interest on theoretical studies of BEC. In this contribution we discuss the statistical mechanics of the trapped BEC at zero temperature. In particular, we study the stability of the condensate by using a variational method with local and non-local interaction between the particles.

Luca Salasnich

1998-03-26

21

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

22

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

23

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.

24

Quantum information processing with trapped electrons and superconducting electronics  

E-print Network

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

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

2013-04-17

25

Microchannels with adhesive posts trap cells with specific mechanical properties  

NASA Astrophysics Data System (ADS)

In order to perform various biological assays and tissue engineering studies, there is a critical need for microfluidic devices that can be used to trap cells with specific mechanical properties. Here, we model cells as fluid filled elastic shells, which also represent polymeric microcapsules. Using a combined approach based on lattice Boltzmann and lattice spring models, we study the motion of cells within a channel with two adhesive posts on the opposite walls. The distance between the posts is comparable to the diameter of the cell. The cells are driven to move through the channel by an imposed pressure gradient. We probe the effect of post compliance and the adhesion strength on the dynamics of the cells. We isolate the conditions at which all cells with shell stiffness lying within a specified range can be trapped in between the posts. Thus, our study can facilitate the design of simple and robust devices for analyzing mechanical properties of biological cells and synthetic microcapsules.

Zhu, Guangdong; Alexeev, Alexander; Balazs, Anna

2007-03-01

26

Monolithic Microfabricated Symmetric Ion Trap for Quantum Information Processing  

E-print Network

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

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

2011-05-24

27

Analysis of dephasing mechanisms in a standing wave dipole trap  

E-print Network

We study in detail the mechanisms causing dephasing of hyperfine coherences of cesium atoms confined by a far off-resonant standing wave optical dipole trap [S. Kuhr et al., Phys. Rev. Lett. 91, 213002 (2003)]. Using Ramsey spectroscopy and spin echo techniques, we measure the reversible and irreversible dephasing times of the ground state coherences. We present an analytical model to interpret the experimental data and identify the homogeneous and inhomogeneous dephasing mechanisms. Our scheme to prepare and detect the atomic hyperfine state is applied at the level of a single atom as well as for ensembles of up to 50 atoms.

S. Kuhr; W. Alt; D. Schrader; I. Dotsenko; Y. Miroshnychenko; A. Rauschenbeutel; D. Meschede

2005-05-02

28

Ultrahigh-Q mechanical oscillators through optical trapping  

NASA Astrophysics Data System (ADS)

Rapid advances are being made toward optically cooling a single mode of a micro-mechanical system to its quantum ground state and observing the quantum behavior at macroscopic scales. Reaching this regime in room-temperature environments requires a stringent condition on the mechanical quality factor Qm and frequency fm, Qmfm ? kBTbath/h, which so far has been marginally satisfied only in a small number of systems. Here we propose and analyze a new class of systems that should enable one to obtain unprecedented Q-frequency products. The technique is based on the use of optical forces to trap and stiffen the motion of a tethered mechanical structure, thereby freeing the resulting mechanical frequencies and decoherence rates from the underlying material properties.

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

2012-04-01

29

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

SciTech Connect

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

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

2011-11-01

30

Precision alignment of integrated optics in surface electrode ion traps for quantum information processing  

NASA Astrophysics Data System (ADS)

The integration of optics for efficient light delivery and the collection of fluorescence from trapped ions in surface electrode ion traps is a key component to achieving scalability for quantum information processing. Diffractive optical elements (DOEs) present a promising approach as compared to bulk optics because of their small physical profile and their flexibility in tailoring the optical wavefront. The precise alignment of the optics for coupling fluorescence to and from the ions, however, poses a particular challenge. Excitation and manipulation of the ions requires a high degree of optical access, significantly restricting the area available for mounting components. The ion traps, DOEs, and other components are compact, constraining the manipulation of various elements. For efficient fluorescence collection from the ions the DOE must be have a large numerical aperture (NA), which results in greater sensitivity to misalignment. The ion traps are sensitive devices, a mechanical approach to alignment such as contacting the trap and using precision motors to back-off a set distance not only cannot achieve the desired alignment precision, but risks damage to the ion trap. We have developed a non-contact precision optical alignment technique. We use line foci produced by off-axis linear Fresnel zone plates (FZPs) projected on alignment targets etched in the top metal layer of the ion trap and demonstrate micron-level alignment accuracy.

Young, Amber L.; Hunker, Jeffrey D.; Ellis, A. Robert; Samora, Sally; Wendt, Joel R.; Stick, Daniel L.

2014-03-01

31

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

32

Mechanics of single kinesin molecules measured by optical trapping nanometry.  

PubMed Central

We have analyzed the mechanics of individual kinesin molecules by optical trapping nanometry. A kinesin molecule was adsorbed onto a latex bead, which was captured by an optical trap and brought into contact with an axoneme that was bound to a glass surface. The displacement of kinesin during force generation was determined by measuring the position of the beads with nanometer accuracy. As the displacement of kinesin was attenuated because of the compliance of the kinesin-to-bead and kinesin-to-microtubule linkages, the compliance was monitored during force generation and was used to correct the displacement of kinesin. Thus the velocity and the unitary steps could be obtained accurately over a wide force range. The force-velocity curves were linear from 0 to a maximum force at 10 microM and 1 mM ATP, and the maximum force was approximately 7 pN, which is larger by approximately 30% than values previously reported. Kinesin exhibited forward and occasionally backward stepwise displacements with a size of approximately 8 nm. The histograms of step dwell time show a monotonic decrease with time. Model calculations indicate that each kinesin head steps by 16-nm, whereas kinesin molecule steps by 8-nm. Images FIGURE 4 FIGURE 8 PMID:9336196

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

1997-01-01

33

Soot Removal Mechanism in an Electric Diesel Particulate Trap  

Microsoft Academic Search

In order to improve the performance of electric diesel particulate trap (E-DPT) that has been proposed by the authors, behavior of trapping and re-burning of diesel soot was investigated using an electric diesel particulate trap with a pair of electro-plates (1-channel E-DPT). The E-DPT was capable to trap soot by applying DC electric field between electro-plates. Experimental results showed that

Hiroyuki Hoshino; Youhei Mitsuyama; Masahiro Saito; Tomohiko Furuhata; Masataka Arai

34

Modeling trapping mechanism for PCB adsorption on activated carbon  

NASA Astrophysics Data System (ADS)

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

Jensen, Bjrnar; Kvamme, Bjrn; Kuznetsova, Tatyana; Oterhals, A.?ge

2012-12-01

35

A mechanism to automatically bait electric grid insect traps with sex pheromone  

Microsoft Academic Search

A mechanism to automatically bait electric grid traps with prospective sex pheromone samples was developed and used during bioassays of chemical components isolated from the extracts of female tobacco budworms,Heliothis virescens (F.). By baiting traps at specified times during the night, this mechanism contributed to the final identification of the sex pheromone.

D. E. Hendricks; C. T. Perez; R. J. Guerra

1975-01-01

36

Breathing-trap mechanism for encapsulation of atomic hydrogen in C60  

E-print Network

Breathing-trap mechanism for encapsulation of atomic hydrogen in C60 Zhongqu Longa , Xiang Zhoua- capsulated in C60 via collisions of either H or H2 with a C60 molecule whose breathing mode has been properly excited by an optimized femtosecond-scale laser pulse. The basic mechanism is a "breathing trap

Allen, Roland E.

37

Cavity QED and quantum information processing with "hot" trapped atoms  

E-print Network

We propose a method to implement cavity QED and quantum information processing in high-Q cavities with a single trapped but non-localized atom. The system is beyond the Lamb-Dick limit due to the atomic thermal motion. Our method is based on adiabatic passages, which make the relevant dynamics insensitive to the randomness of the atom position with an appropriate interaction configuration. The validity of this method is demonstrated from both approximate analytical calculations and exact numerical simulations. We also discuss various applications of this method based on the current experimental technology.

L. -M. Duan; A. Kuzmich; H. J. Kimble

2002-08-08

38

A family of synthetic riboswitches adopts a kinetic trapping mechanism  

PubMed Central

Riboswitches are sequences of RNA that control gene expression via RNAligand interactions, without the need for accessory proteins. Riboswitches consist of an aptamer that recognizes the ligand and an expression platform that couples ligand binding to a change in gene expression. Using in vitro selection, it is possible to screen large (?1013 members) libraries of RNA sequences to discover new aptamers. However, limitations in bacterial transformation efficiency make screening such large libraries for riboswitch function in intact cells impractical. Here we show that synthetic riboswitches function in an E. coli S30 extract in a manner similar to how they function in intact E. coli cells. We discovered that, although this family of riboswitches regulates the initiation of protein translation, the fate of whether an RNA message is translated is determined during transcription. Thus, ligand binding does not bias a population of rapidly equilibrating RNA structures, but rather, co-transcriptional ligand binding kinetically traps the RNA in a conformation that supports efficient translation. In addition to providing new insights into the mechanisms of action of a family of synthetic riboswitches, our experiments suggest that it may be possible to perform selections for novel synthetic riboswitches in an in vitro system. PMID:24782524

Mishler, Dennis M.; Gallivan, Justin P.

2014-01-01

39

Investigation of Aging Mechanisms in Lean NOx Traps  

SciTech Connect

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

Mark Crocker

2010-03-31

40

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

Microsoft Academic Search

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

Yun Mook Lim; Victor C. Li

1997-01-01

41

Magnetic trapping of neutral particles: Classical and quantum-mechanical study of a Ioffe-Pritchard type trap  

NASA Astrophysics Data System (ADS)

Recently, we developed a method for calculating the lifetime of a particle inside a magnetic trap with respect to spin flips, as a first step in our efforts to understand the quantum mechanics of magnetic traps. The one-dimensional toy model that was used in this study was physically unrealistic because the magnetic field was not curl free. Here, we study, both classically and quantum mechanically, the problem of a neutral particle with spin S, mass m, and magnetic moment ?, moving in three dimensions in an inhomogeneous magnetic field corresponding to traps of the Ioffe-Pritchard "clover-leaf" and "baseball" type. Defining by ?p, ?z, and ?r the precessional, the axial, and the lateral vibrational frequencies, respectively, of the particle in the adiabatic potential Veff=?|B|, we find classically the region in the (?r/?p)-(?z/?p) plane where the particle is trapped. Quantum mechanically, we study the problem of a spin-one particle in the same field. Treating ?r/?p and ?z/?p as small parameters for the perturbation from the adiabatic Hamiltonian, we derive a closed-form expression for the transition rate 1/Tesc of the particle from its trapped ground state. In the extreme cases, the expression for 1/Tesc reduces to 4??rexp(-2?p/?r) for ?p??r??z, to 8?2? ??p?i exp(-2?p/?i) for ?p??r=?z??i and to ??/2 ?r(?z/?p)3/2exp(-2?p/?z) for ?p??z??r.

Gov, S.; Shtrikman, S.; Thomas, H.

2000-04-01

42

Kibble-Zurek mechanism in a trapped ferromagnetic Bose-Einstein condensate  

NASA Astrophysics Data System (ADS)

Spontaneous spin vortex formation in a magnetic phase transition of a trapped spin-1 Bose-Einstein condensate is investigated based on mean-field theory. In a harmonic trapping potential, an inhomogeneous atomic density leads to spatial variations of the critical point, magnetization time, and spin correlation length. The Kibble-Zurek phenomena are shown to emerge even in such inhomogeneous spinor condensates, when the quench of the quadratic Zeeman energy is fast enough. For slow quench, the magnetized region gradually expands from the center of the trap, pushing out spin vortices, which hinders the Kibble-Zurek mechanism from occurring. The case of a toroidal trapping potential is also discussed.

Saito, Hiroki; Kawaguchi, Yuki; Ueda, Masahito

2013-10-01

43

Adiabatic processes realized with a trapped brownian particle.  

PubMed

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

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

2015-03-27

44

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

E-print Network

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

Navarro, Sergio Michael

2008-01-01

45

Mechanical design of process systems  

Microsoft Academic Search

This text shows how to design equipment\\/components using techniques available in heat transfer, hydraulics, and static and dynamic analyses. Chemical, mechanical, civil, and nuclear engineers in the petrochemical, food processing, pharmaceutical, power generation, and ship-building industries will find insights into solving process system design problems. All the techniques and data are ''field tested,'' and some are published here for the

Escoe

1986-01-01

46

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

47

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; Ahrn, Dag

2013-01-01

48

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

49

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

50

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

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

51

Excitation-assisted inelastic processes in trapped Bose-Einstein condensates  

E-print Network

We find that inelastic collisional processes in Bose-Einstein condensates induce local variations of the mean-field interparticle interaction and are accompanied by the creation/annihilation of elementary excitation. The physical picture is demonstrated for the case of three body recombination in a trapped condensate. For a high trap barrier the production of high energy trapped single particle excitations results in a strong increase of the loss rate of atoms from the condensate.

D. Guery-Odelin; G. V. Shlyapnikov

1999-05-28

52

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

53

Microfabricated Surface-Electrode Ion Trap for Scalable Quantum Information Processing  

SciTech Connect

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

Seidelin, S.; Chiaverini, J.; Reichle, R.; Bollinger, J.J.; Leibfried, D.; Britton, J.; Wesenberg, J.H.; Blakestad, R.B.; Epstein, R.J.; Hume, D.B.; Itano, W.M.; Jost, J.D.; Langer, C.; Ozeri, R.; Shiga, N.; Wineland, D.J. [Time and Frequency Division, NIST, Boulder, Colorado 80305 (United States)

2006-06-30

54

Process Waste Assessment, Mechanics Shop  

SciTech Connect

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

Phillips, N.M.

1993-05-01

55

Kibble-Zurek mechanism in a trapped ferromagnetic Bose-Einstein condensate.  

PubMed

Spontaneous spin vortex formation in a magnetic phase transition of a trapped spin-1 Bose-Einstein condensate is investigated based on mean-field theory. In a harmonic trapping potential, an inhomogeneous atomic density leads to spatial variations of the critical point, magnetization time, and spin correlation length. The Kibble-Zurek phenomena are shown to emerge even in such inhomogeneous spinor condensates, when the quench of the quadratic Zeeman energy is fast enough. For slow quench, the magnetized region gradually expands from the center of the trap, pushing out spin vortices, which hinders the Kibble-Zurek mechanism from occurring. The case of a toroidal trapping potential is also discussed. PMID:24025530

Saito, Hiroki; Kawaguchi, Yuki; Ueda, Masahito

2013-10-01

56

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

57

Charge trapping\\/detrapping induced lattice polarization\\/relaxation processes  

Microsoft Academic Search

The consequence of the coupling of a charged particle with a polarization field is the formation of a quasi particle called polaron. The degree of localization of the charge depends on the nature of this coupling. In this way, trapping at an atomic scale is described as resulting from the evolution of a coupling involving successively the electronic polarization field,

G. Blaise

1995-01-01

58

Emplacement mechanisms and trapping potential of gravity-driven allochthons  

SciTech Connect

Gravity-slide blocks of Paleozoic carbonate detached from the Snake River Range show evidence of episodic emplacement into the Salt Lake group (Mio-Pliocene) in the Palisades reservoir area near Alpine, Wyoming. The allochthons lie in a large graben system created by the Grand Valley listric normal fault, a reactivated thrust that soles into a ramp in the underlying Absaroka thrust. In the Alpine 7 1/2-min quadrangle, one of the detached blocks is 2 1/2 mi (4 km) by 1 mi (1.6 km) in map view and contains the Ferry Peak thrust as well as other Laramide structures. Structures and formations of the Alpine allochthon may be matched to those in the range to restore approximate predetachment position. Very low-angle westward translation at or near the surface moved the blocks across the Grand Valley fault into the graben. The current location and attitude of these allochthons are due to subsequent movement and rotation on the Grand Valley fault. The allochthons occur at different stratigraphic levels in the Salt Lake group, each level corresponding to the time of a specific emplacement event. Catastrophic emplacement of a fractured allochthon, a potential reservoir, into a lacustrine or other source rock depocenter creates a unique and potentially predictable type of petroleum occurrence. Paleogeographic reconstruction may explain anomalous occurrence of discrete allochthons in structurally low areas where it can be shown that a gravitational potential existed for detachment and sliding. The resulting trap would consist of allochthons encased in autochthonous source rock.

Pinney, R.B.

1985-02-01

59

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...

60

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.

61

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

E-print Network

Lysosomal trapping of a radiolabeled substrate of P-glycoprotein as a mechanism for signal, 2010) The radiotracer [11 C]N-desmethyl-loperamide (dLop) images the in vivo function of P-glycoprotein | efflux The efflux transporter P-glycoprotein (P-gp; encoded by ABCB1) blocks the entry of various

Shen, Jun

62

Mechanism of AMPA receptor activation by partial agonists: disulfide trapping of closed lobe conformations.  

PubMed

The mechanism by which agonist binding to an ionotropic glutamate receptor leads to channel opening is a central issue in molecular neurobiology. Partial agonists are useful tools for studying the activation mechanism because they produce full channel activation with lower probability than full agonists. Structural transitions that determine the efficacy of partial agonists can provide information on the trigger that begins the channel-opening process. The ligand-binding domain of AMPA receptors is a bilobed structure, and the closure of the lobes is associated with channel activation. One possibility is that partial agonists sterically block full lobe closure but that partial degrees of closure trigger the channel with a lower probability. Alternatively, full lobe closure may be required for activation, and the stability of the fully closed state could determine efficacy with the fully closed state having a lower stability when bound to partial relative to full agonists. Disulfide-trapping experiments demonstrated that even extremely low efficacy ligands such as 6-cyano-7-nitroquinoxaline-2,3-dione can produce a full lobe closure, presumably with low probability. The results are consistent the hypothesis that the efficacy is determined at least in part by the stability of the state in which the lobes are fully closed. PMID:21846932

Ahmed, Ahmed H; Wang, Shu; Chuang, Huai-Hu; Oswald, Robert E

2011-10-01

63

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

64

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

65

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

66

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

67

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

SciTech Connect

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

Javanainen, Juha [Department of Physics, University of Connecticut, Storrs, Connecticut 06269-3046 (United States)

2010-05-15

68

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

PubMed Central

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

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

2013-01-01

69

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

PubMed

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

2009-11-24

70

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

PubMed Central

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

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

2009-01-01

71

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

72

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

73

On the mechanism of mountain cold-trapping of organic chemicals.  

PubMed

The preferential accumulation of selected organic pollutants at higher altitude has been observed in a number of mountain regions. It is proposed that this phenomenon is due to differences in the efficiency of precipitation scavenging at various elevations, which, in turn, is due to the temperature dependence of organic vapor partitioning into rain, snow, and aerosols. The occurrence and extent of enrichment with elevation depends on whether the scavenging efficiency of a chemical is sensitive to temperature within the range encountered along a mountain slope. A multicompartment fate and transport model parameterized for mountain systems suggeststhat substances with equilibrium partitioning coefficients at 25 degrees C between water and air from 10(3.5) to 10(5.5) and between atmospheric particles and air from 10(9) to 10(11) are most likely to be subject to mountain cold-trapping. Such substances remain in the atmospheric vapor phase at higher valley temperatures, but are scavenged efficiently at the lower temperatures prevailing at higher altitudes. This implies that substances subject to mountain cold-trapping are approximately 2 orders of magnitude less volatile than substances that experience global cold-trapping. For example, while lighter PCBs get preferentially trapped at higher latitudes, the heavier PCBs are predicted to experience the strongest mountain cold-trapping. These model results agree with the results of field studies, with the exception of those studies that rely on sample media such as plant foliage for which precipitation is not the dominant deposition pathway. It appears that very fast deposition processes are required to trap contaminants along mountain slopes, whereas such processes reduce contaminant transport to remote polar regions. PMID:19174876

Wania, Frank; Westgate, John N

2008-12-15

74

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

75

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...

76

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

77

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

78

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

79

Photorefractive phase-conjugate optics for image processing, trapping, and manipulation of microscopic objects  

Microsoft Academic Search

Optical phase conjugation using photorefractive materials can be readily integrated with laser microscopy and interferometry for image processing, trapping, and manipulation of microscopic objects. This paper briefly reviews the basic principles associated with each individual component and describes some recent developments and potential biological applications of their integration

ARTHUR E. CHIOU

1999-01-01

80

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

E-print Network

and ther- mophoretic forces.5 High plasma density tools ( e 1011 ­1012 cm 3 ), such as inductively coupledRegimes of particle trapping in inductively coupled plasma processing reactors Helen H. Hwanga) and Mark J. Kushnerb) University of Illinois, Department of Electrical and Computer Engineering, 1406 W

Kushner, Mark

81

Oxidation processes of chromium dimer and trimer cations in an ion trap  

NASA Astrophysics Data System (ADS)

Oxidation processes of chromium cluster cations, Cr2+ and Cr3+, are investigated by kinetics measurements under multiple-collision conditions by using a temperature-controlled ion trap. Both of the reactants commonly generate Cr+ and CrO+ as final products. However, the major reaction pathway to CrO+ presents a sharp contrast; Cr2+ produces it directly by a single O2 collision, whereas Cr3+ does via an intermediate Cr2O+. Comparison of the kinetics of the intermediate with that of cold Cr2O+ generated in the cluster source reveals that the intermediate Cr2O+ is thermalized promptly with the buffer gas filling the trap.

Ito, Tomonori; Egashira, Kazuhiro; Tsukiyama, Koichi; Terasaki, Akira

2012-06-01

82

Diffusion and bulk flow in phloem loading - a theoretical analysis of the polymer trap mechanism  

E-print Network

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 analyse 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 heav...

Dlger, Julia; Liesche, Johannes; Schulz, Alexander; Bohr, Tomas

2014-01-01

83

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

PubMed

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

84

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

85

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

86

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

NASA Technical Reports Server (NTRS)

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

Palmadesso, Peter J.

1990-01-01

87

Double-structure potential due to multiphoton processes in a magneto-optical trap  

Microsoft Academic Search

We have derived ab initioanalytical results for the shape of the double-structure potential well for a (3+5)-level atoms in the magneto-optical trap (MOT). We show that for a case of a (3+5)-level atom and a one-dimensional sigma+-sigma- laser field, the sharp bottom part of the MOT potential well results from the two-photon processes between the atomic ground-state magnetic sublevels. These

Jin Woo Jun; Soo Chang; Ho Seong Lee; Vladimir Minogin; Wonho Jhe

1999-01-01

88

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

E-print Network

, such as magnetic bearings [6, 7], and high power density rotating machines [8-12] because it can trap a high valueInfluence of the inductor shape, and the magnetization processes on a trapped magnetic flux.gony@univ-lorraine.fr Abstract. In this paper, we study the form of the inductor for producing a magnetic field

Boyer, Edmond

89

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

90

A Process Model of Quantum Mechanics  

E-print Network

A process model of quantum mechanics utilizes a combinatorial game to generate a discrete and finite causal space upon which can be defined a self-consistent quantum mechanics. An emergent space-time M and continuous wave function arise through a non-uniform interpolation process. Standard non-relativistic quantum mechanics emerges under the limit of infinite information (the causal space grows to infinity) and infinitesimal scale (the separation between points goes to zero). The model has the potential to address several paradoxes in quantum mechanics while remaining computationally powerful.

William Sulis

2014-04-21

91

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

NASA Astrophysics Data System (ADS)

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

Ortel, Marlis; Pittner, Steve; Wagner, Veit

2013-04-01

92

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

93

Unpacking Cognitive Search Mechanisms and Processes  

E-print Network

issues relevant across all types of search are distinguished: (a) the initiation of search, (b15 Unpacking Cognitive Search Mechanisms and Processes Thorsten Pachur, Jeroen G. W. Raaijmakers commonalities and differences in the cognitive mechanisms un- derlying different search tasks, such as spatial

94

Collective mechanisms for atomic processes in plasmas  

Microsoft Academic Search

New mechanisms for atomic processes in plasmas induced by the collective behavior of the system are proposed, the collective behavior being a consequence of the long range of the Coulomb forces between the (charged) particles. These new mechanisms are hydrogen recombination with plasmon emission, ionization by plasmon absorption, and bound-bound and free-free atomic transitions with emission or absorption of plasmons.

Gutierrez Rivera

1988-01-01

95

Collective Mechanisms for Atomic Processes in Plasmas  

Microsoft Academic Search

New mechanisms for atomic processes in plasmas induced by the collective behavior of the system are proposed, the collective behavior being a consequence of the long range of the Coulomb forces between the (charged) particles. These new mechanisms are hydrogen recombination with plasmon emission, ionization by plasmon absorption, and bound-bound and free-free atomic transitions with emission or absorption of plasmons.

Fernando Alfonso Gutierrez Rivera

1988-01-01

96

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

E-print Network

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

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

2012-04-09

97

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

98

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

E-print Network

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.

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

2014-06-24

99

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

NASA Astrophysics Data System (ADS)

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 are also discussed. In addition to the BEC mechanism, plasma impact fusion (PIF) and particle cavitation fusion (PCF) mechanisms are also described.

Kim, Y. E.

100

Process Modeling of Chemical Mechanical Polishing (CMP)  

Microsoft Academic Search

In this report, the modeling process of CMP process based on prediction of material removal rate (MRR) and pressure and velocity distribution over wafer -pad interface is discussed. Software to predict MRR and with-in wafer non-uniformity (WIWNU) is being developed. 1. CMP and CMP Model The chemical mechanical polishing (CMP) has been widely accepted in the semic onductor industry for

Jianfeng Luo

101

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

102

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

103

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

104

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

105

Interface mechanics of adhesiveless microtransfer printing processes  

NASA Astrophysics Data System (ADS)

Microtransfer printing is a versatile process for retrieving, transferring, and placing nanomembranes of various materials on a diverse set of substrates. The process relies on the ability to preferentially propagate a crack along specific interfaces at different stages in the process. Here, we report a mechanics-based model that examines the factors that determine which interface a crack will propagate along in microtransfer printing with a soft elastomer stamp. The model is described and validated through comparison to experimental measurements. The effects of various factors, including interface toughness, stamp geometry, flaw sizes at the interfaces, and nanomembrane thickness, on the effectiveness of transfer printing are investigated using a fracture-mechanics framework and finite element modeling. The modeling results agree with experimental measurements in which the effects of interface toughness and nanomembranes thickness on the transfer printing yield were examined. The models presented can be used to guide the design of transfer printing processes.

Kim-Lee, H.-J.; Carlson, A.; Grierson, D. S.; Rogers, J. A.; Turner, K. T.

2014-04-01

106

The Electron Trap Mechanism of Luminescence in Sulphide and Silicate Phosphors  

Microsoft Academic Search

Phosphorescence and thermoluminescence emission from photoconducting impurity activated phosphors have been satisfactorily explained by the storage of electrons, freed from luminescence centres or other atoms of the solid, in metastable energy levels known as electron traps. Electrons escaping from these traps give rise to emission when they recombine with luminescence centres but there is a probability that they may be

G F J Garlick; A F Gibson

1948-01-01

107

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

PubMed

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

Nitayapat, Nuttakan; Chitprasert, Pakamon

2014-06-01

108

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

109

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

110

From organic single crystals to solution processed thin-films: Charge transport and trapping with varying degree of order  

NASA Astrophysics Data System (ADS)

We have fabricated single crystal, thermally evaporated, and spin-coated thin-film transistors (TFTs) from the same organic semiconductor N,N'-1H,1H-perfluorobutyl dicyanoperylene carboxydiimide (PDIF-CN2) using various combinations of deposition methods and gate dielectrics to investigate how the charge transport properties vary with the degree of crystalline order. Never before has a semiconductor been studied in such a wide variety of processing methods, allowing cross-comparison of the microscopic factors influencing the charge transport, and in particular the trap density of states (DOS). Excellent transistor performance was achieved for PDIF-CN2 single crystals in combination with Cytop as a dielectric layer resulting in a mobility of up to 6 cm2/Vs, an on/off-ratio exceeding 108, and a subthreshold swing of 0.45 V/dec. Furthermore, gate-bias-stress effects are not present in these transistors and we observed low stress effects in the evaporated TFTs with Cytop as the gate dielectric. These findings are reflected in the trap DOS. The single crystal field-effect transistor with Cytop has a low trap DOS, whereas in evaporated TFTs, the trap DOS is higher by 2-3 orders of magnitude. Surprisingly, the trap DOS of the spin-coated TFT is similar to that in evaporated TFTs, except for additional discrete trap states centered around 0.24 eV below the conduction band.

Willa, K.; Husermann, R.; Mathis, T.; Facchetti, A.; Chen, Z.; Batlogg, B.

2013-04-01

111

Underlying mechanisms for commuting and migration processes  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

112

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

113

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

Microsoft Academic Search

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

Yeong E. Kim; Thomas O. Passell

2006-01-01

114

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

Microsoft Academic Search

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

Yeong E. Kim; Thomas O. Passell

115

Collective Mechanisms for Atomic Processes in Plasmas.  

NASA Astrophysics Data System (ADS)

New mechanisms for atomic processes in plasmas induced by the collective behavior of the system are proposed, the collective behavior being a consequence of the long range of the Coulomb forces between the (charged) particles. These new mechanisms are hydrogen recombination with plasmon emission, ionization by plasmon absorption, and bound-bound and free-free atomic transitions with emission or absorption of plasmons. The Bohm-Pines Fock-Tani Hamiltonian for a proton at rest immersed in a finite temperature plasma (in the electron gas model), is obtained from first principles by a sequence of canonical transformations. This Hamiltonian shows explicitly the new proposed reaction and scattering mechanisms, in which, the emission or absorption of plasmons allow the process to occur. An effective potential for the hydrogen atom in a plasma is obtained which is very similar to the Ecker-Weizel potential used to interpret the plasma shifts of the discrete and continuous spectra of hydrogen. We interpret the negative shift of the proton as arising from emission and absorption of virtual plasmons. Expressions for plasmonic recombination matrix elements in the orthogonalized Born approximation (OBA) and the distorted wave Born approximation (DWBA) are given in terms of 6- or 12-dimensional integrals which are reduced analytically to 2-dimensional integrals. The generalization to the case of a slowly moving proton introduces an extra momentum conservation Kronecker delta factor in the matrix elements. Explicit evaluations of the cross section for the plasmonic and radiative recombination in the (OBA) are obtained for n = 10^{18} cm^{-3} and kT = 0.5 eV and for the states n = 8,9, ~l = 0,1, and m = 0. The results indicate that the radiative mechanism is negligible compared to the plasmonic mode for the value of the parameters and quantum numbers indicated above. This result points to the fact that the plasmonic mode should be compared to the mechanism usually assumed to be dominant for the regime under consideration, namely three-body recombination. Finally by using a generalized Schroedinger equation for composite particles in a medium we recalculate the energy shift of a hydrogen atom produced by the exchange between a free electron and the bound atomic electron. The result shows that the shifts are important for the highly excited states of atoms in plasmas.

Gutierrez Rivera, Fernando Alfonso

116

MECHANISMS UNDERLYING THE EFFECTIVENESS OF FOOD PROCESSING IPM PROGRAMS  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

117

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...

118

Electron Trapping by the Electric Field Inversion Mechanism in a dc Glow Discharge  

Microsoft Academic Search

We investigate the existence of the electric field reversal in the negative glow of a dc discharge, its location, the width of the well trapping the electrons, the slow electrons scattering time as well the fraction of ions build up in the glow and returning to cathode. A simple analytical model is presented which includes a Boltzmann transport equations for

Mario J. Pinheiro

2000-01-01

119

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

120

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.

121

Hydrogeochemical numerical simulation of impacts of mineralogical compositions and convective fluid flow on trapping mechanisms and efficiency of carbon dioxide injected into deep saline sandstone aquifers  

NASA Astrophysics Data System (ADS)

A series of numerical simulations, which consider density-dependent (convective) groundwater and carbon dioxide (CO2) flow, is performed using a multiphase hydrogeochemical reactive transport numerical model to evaluate impacts of mineralogical compositions on the trapping mechanisms and efficiency of CO2 injected into a deep saline sandstone aquifer (reservoir rock). The results of the numerical simulations show that the mineralogical compositions of the sandstone aquifer have significant impacts on hydrogeochemical behavior of injected CO2 and thus its trapping mechanisms and efficiency. Injected CO2 is accumulated as a free fluid phase beneath the caprock (i.e., hydrodynamic trapping), then dissolved as aqueous phases such as bicarbonate and carbonate anions into groundwater (i.e., solubility trapping), and finally precipitated as carbonate minerals (i.e., mineral trapping). Mineral trapping of injected CO2 takes places as precipitation of a primary carbonate mineral such as calcite and secondary carbonate minerals such as dawsonite, siderite, ankerite, and magnesite. The patterns of hydrogeochemical reactions depend significantly on the initial presence and absence of chlorite in the sandstone aquifer. For mineral trapping of injected CO2, ankerite is the most dominant mineral when chlorite is initially present, whereas dawsonite is the most dominant mineral when chlorite is initially absent in the sandstone aquifer. Mg2+ and Fe2+, which are essential chemical components of such secondary carbonate minerals (i.e., siderite, ankerite, and magnesite) for mineral trapping of injected CO2, are mainly supplied by dissolution of chlorite. As a result, the precipitation amounts of the secondary carbonate minerals and thus the efficiency of mineral trapping of injected CO2 increase significantly as the volume fraction of chlorite increases in the sandstone aquifer. A series of additional numerical simulations, which consider density-independent (non-convective) multiphase fluid flow, is also performed using the same numerical model, and then its results are compared with those of the above-mentioned numerical simulations, which consider density-dependent (convective) multiphase fluid flow, to evaluate impacts of convective fluid flow on the trapping mechanisms and efficiency of injected CO2. The comparison of the results of both numerical simulations shows that convective fluid flow also has significant impacts on hydrogeochemical behavior of injected CO2 and thus its trapping mechanisms and efficiency. Convective fluid flow reduces the free fluid phase of CO2 (i.e., hydrodynamic trapping) and thus enhances the aqueous and solid phases of CO2 (i.e., initially solubility trapping and then mineral trapping).

Kihm, Jung-Hwi; Kim, Jun-Mo; Wang, Sookyun; Xu, Tianfu

2012-06-01

122

Aqueous Electrochemical Mechanisms in Actinide Residue Processing  

SciTech Connect

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 Energy's (DOE) legacy waste from fifty years of nuclear weapons production activities. Much of this material is presently in storage at sites throughout the DOE weapons production complex (most notably Rocky Flats, Savannah River and Hanford) awaiting further processing and/or final disposition. The chemical and physical stability of much of this material has been called into question recently by the Defense Nuclear Facility Safety Board (DNFSB) and resulted in the issuance of a mandate by the DNFSB to undertake a program to stabilize these materials [1]. The ultimate disposition for much of these materials is anticipated to be geologic repositories such as the proposed Waste Isolation Pilot Plant in New Mexico. However, in light of the mandate to stabilize existing residues and the probable concomitant increase in the volume of material to be disposed as a result of stabilization (e.g., from repackaging at lower residue densities), the projected storage volume for these wastes within anticipated geologic repositories will likely be exceeded simply to handle existing wastes. Additional processing of some of these residue waste streams to reduce radionuclide activity levels, matrix volume, or both is a potentially important strategy to achieve both stabilization and volume reduction so that the anticipated geologic repositories will provide adequate storage volume. In general, the plutonium and uranium that remains in solid residue materials exists in a very stable chemical form (e.g., as binary oxides), and the options available to remove the actinides are limited. However, there have been some demonstrated successes in this vain using aqueous phase electrochemical methods such as the Catalyzed Electrochemical Plutonium Oxide Dissolution (CEPOD) process pioneered by workers at Pacific Northwest National Laboratory in the mid-1970s [2]. The basis for most of these mediated electrochemical oxidation/reduction (MEO/R) processes is the generation of a dissolved electrochemical catalyst, such as Ag2+, which is capable of oxidizing or reducing solid-phase actinide species or actinide sorbates via 7 heterogeneous electron transfer to oxidation states that have significantly greater solubilities (e.g., PuO2(s) to PuO2 2+ (dissolved)). The solubilized actinide can then be recovered by ion exchange or other mechanisms. These aqueous electrochemical methods for residue treatment have been considered in many of the ''trade studies'' to evaluate options for stabilization of the various categories of residue materials. While some concerns generally arise (e.g., large secondary waste volumes could results since the process stream normally goes th rough anion exchange or precipitation steps to remove the actinide), the real utility and versatility of these methods should not be overlooked. They are low temperature, ambient pressure processes that operate in a non-corrosive environment. In principle, they can be designed to be highly selective for the actinides (i.e., no substrate degradation occurs), they can be utilized for many categories of residue materials with little or no modification in hardware or operating conditions, and they can conceivably be engineered to minimize secondary waste stream volume. However, some fundamental questions remain concerning the mechanisms through which these processes act, and how the processes might be optimized to maximize efficiency while minimizing secondary waste. In addition, given the success achieved to date on the limited set of residues, further research is merited to extend the range of applicability of these electrochemical methods to other residue and waste streams. The principal goal of the work described here is to develop a fundamental understanding of the heterogeneous electron transfer thermodynamics a

Morris, David E.; Burns, Carol J.; Smith, Wayne H.; Blanchard

2000-12-31

123

Separable Mechanisms in Face Processing: Evidence from Hemispheric Specialization  

Microsoft Academic Search

This article addresses three issues in face processing: First, is face processing primarily accomplished by the right hemisphere, or do both left- and right-hemisphere mechanisms play important roles? Second, are the mechanisms the same as those involved in general visual processing, or are they dedicated to face processing? Third, how can the mechanisms be characterized more precisely in terms of

Lynn A. Hillger; Olivier Koenig

1991-01-01

124

Chemical Mechanical Planarization of Cu: Nanoscale Processes  

NASA Astrophysics Data System (ADS)

Interconnect lines in state of the art integrated circuits are made of copper in a process that requires the repeated planarization of the copper layer. During this process the material is subjected to an aqueous slurry containing active chemicals, corrosion inhibitors and abrasive particles. A model slurry buffered to pH2, pH4 and pH6, contained nitric acid, silica particles and benzotriazole (BTA) as a corrosion inhibitor. The degree of copper planarization was investigated as a function of slurry composition and pH using atomic force microscopy. Chemical surface changes can be explained by the effect of slurry composition on the charge at the material surface. This surface charge controls the amount of friction between the abrasive and the surface which, in turn, effects the global planarization of the material. Experiments using a macroscopic polishing system with AFM characterization along with the microscopic interaction of the AFM tip and sample provide insights into the fundamental mechanisms of a planarization process.

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

2002-10-01

125

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

126

Redox potential determines the reaction mechanism of HNO donors with Mn and Fe porphyrins: defining the better traps.  

PubMed

Azanone ((1)HNO, nitroxyl) is a highly reactive molecule with interesting chemical and biological properties. Like nitric oxide (NO), its main biologically related targets are oxygen, thiols, and metalloproteins, particularly heme proteins. As HNO dimerizes with a rate constant between 10(6) and 10(7) M(-1) s(-1), reactive studies are performed using donors, which are compounds that spontaneously release HNO in solution. In the present work, we studied the reaction mechanism and kinetics of two azanone donors Angels Salt and toluene sulfohydroxamic acid (TSHA) with eight different Mn porphyrins as trapping agents. These porphyrins differ in their total peripheral charge (positively or negatively charged) and in their Mn(III)/Mn(II) reduction potential, showing for each case positive (oxidizing) and negative (reducing) values. Our results show that the reduction potential determines the azanone donor reaction mechanism. While oxidizing porphyrins accelerate decomposition of the donor, reducing porphyrins react with free HNO. Our results also shed light into the donor decomposition mechanism using ab initio methods and provide a thorough analysis of which MnP are the best candidates for azanone trapping and quantification experiments. PMID:25001488

Alvarez, Luca; Suarez, Sebastin A; Bikiel, Damian E; Reboucas, Julio S; Batini?-Haberle, Ines; Mart, Marcelo A; Doctorovich, Fabio

2014-07-21

127

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

128

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

129

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 35C. 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. Sillanp

2009-01-01

130

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)

131

Heating rate and electrode charging measurements in a scalable, microfabricated, surface-electrode ion trap  

E-print Network

We characterise the performance of a surface-electrode ion "chip" trap fabricated using established semiconductor integrated circuit and micro-electro-mechanical-system (MEMS) microfabrication processes which are in principle scalable to much larger ion trap arrays, as proposed for implementing ion trap quantum information processing. We measure rf ion micromotion parallel and perpendicular to the plane of the trap electrodes, and find that on-package capacitors reduce this to heating rate for a single trapped ion. The performance of this trap is found to be comparable with others of the same size scale.

D. T. C. Allcock; T. P. Harty; H. A. Janacek; N. M. Linke; C. J. Ballance; A. M. Steane; D. M. Lucas; R. L. Jarecki Jr.; S. D. Habermehl; M. G. Blain; D. Stick; D. L. Moehring

2011-05-24

132

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

Microsoft Academic Search

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

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

2003-01-01

133

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

134

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

135

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.

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

1998-01-01

136

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

137

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

SciTech Connect

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, E-mail: bodensiek@physik3.gwdg.de; Li, Weixing [III. Physikalisches Institut, Georg-August-Universitt, Gttingen (Germany)] [III. Physikalisches Institut, Georg-August-Universitt, Gttingen (Germany); Snchez, Paula; Nawaz, Schanila; Schaap, Iwan A. T. [III. Physikalisches Institut, Georg-August-Universitt, Gttingen (Germany) [III. Physikalisches Institut, Georg-August-Universitt, Gttingen (Germany); Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Gttingen (Germany)

2013-11-15

138

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

139

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...

140

KINETICS AND MECHANISMS OF SOIL BIOGEOCHEMICAL PROCESSES  

EPA Science Inventory

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

141

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

E-print Network

such as security technology, transport and logistics, agriculture and forestry services,internet applications, and making products to improve the quality of human life and shape the economy. Mechanical engineers apply such as aerospace, automotive, dairy, energy, product and plant design, pulp and paper, as well as shipping

Waikato, University of

142

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

143

Surface reaction mechanisms in plasma etching processes  

Microsoft Academic Search

Plasma etching is an essential process in the fabrication of submicron features in the semiconductor industry. Plasma-surface interactions in plasma etching processes are capable of influencing bulk plasma properties as well as determining etch rates and feature profiles. To address the coupling of plasma and surface processes, the Surface Kinetics Model (SKM) was developed and was linked to the Hybrid

Da Zhang

2000-01-01

144

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.

Vronique Gayrard; Adela Svejda

2015-01-13

145

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

146

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

147

Formation of radicals by mechanical processes.  

PubMed

The application of e.s.r. spectroscopy to the study of radicals formed by mechanical means (grinding, shearing, bending, cutting, etc.) is discussed. Two mechanisms are considered, one being the homolytic breaking of main-chain bonds in polymers, and the other being charge-transfer (tribo-electric effect). The former is thought to occur for high polymers whilst the latter may be important for certain inorganic materials especially ionic solids. Specific examples are given for the generation of radicals by cutting finger nails and by grinding bone. In both cases, well-defined e.s.r. spectra were obtained for which identifications are offered. Possible implications of the mechanical formation of radicals in bone are considered. PMID:2853116

Symons, M C

1988-01-01

148

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

149

Aqueous Electrochemical Mechanisms in Actinide Residue Processing  

Microsoft Academic Search

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 Energy's (DOE) legacy waste from fifty years of nuclear weapons production activities. Much of this material is presently in storage at sites

David E. Morris; Carol J. Burns; Wayne H. Smith; Blanchard

2000-01-01

150

Chemical Mechanical Planarization of Cu: Nanoscale Processes  

Microsoft Academic Search

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

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

2002-01-01

151

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

PubMed Central

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

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

2009-01-01

152

Scheme for Quantum Cloning and Quantum Information Processing with Trapped Ions  

NASA Astrophysics Data System (ADS)

In this paper, a scheme is presented to implement the 1?2 universal quantum cloning machine (UQCM) with trapped ions. In this way, we also show that quantum information can be directly transferred from one ion to another. The distinct advantage of the scheme lies in the fact that it does not use the vibrational mode as the data bus. The vibrational mode is only virtually excited, which makes our scheme insensitive to heating, provided the system remains in the Lamb-Dicke regime.

Zhan, Zhi-Ming

153

Benchmarking Peer Production Mechanisms, Processes & Practices  

ERIC Educational Resources Information Center

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

Fischer, Thomas; Kretschmer, Thomas

2008-01-01

154

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.

155

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

156

Charge-trapping effect of doped fluorescent dye on the electroluminescent processes and its performance in polymer light-emitting diodes  

Microsoft Academic Search

We have measured the temperature dependence of the steady-state current-voltage (IV) characteristics and the transient electroluminescent (EL) characteristics in 4-(dicyanomethylene)-2-t-propyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped polyfluorene devices to study the charge-trapping effect of DCJTB fluorescent dye on luminescence processes and on device performance. Physical and chemical analyses prove that DCJTB molecules serve both as electron and hole traps, and the charge-trapping effect is

Tengling Ye; Zhenyu Chen; Jiangshan Chen; Dongge Ma

2010-01-01

157

Volcanic ash layer depth: Processes and mechanisms  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

158

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

159

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.

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

2014-10-01

160

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

PubMed

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

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

2014-10-01

161

Multiple Mechanisms of Top-Down Processing in Vision  

E-print Network

21 2 Multiple Mechanisms of Top-Down Processing in Vision Giorgio Ganis1,2,3 and Stephen M. Kosslyn be usefully supplemented by using stored information, engaging in processing that is "top down"--driven by stored knowledge, goals, or expecta- tions. In this chapter we explore the nature of top-down processing

Ganis, Giorgio

162

Penning trap mass measurements on (99-109)$Cd with ISOLTRAP and implications on the rp process  

E-print Network

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

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

2009-08-18

163

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

E-print Network

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

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

2009-01-01

164

Penning trap mass measurements of Cd99-109 with the ISOLTRAP mass spectrometer, and implications for the rp process  

NASA Astrophysics Data System (ADS)

Penning trap mass measurements of neutron-deficient Cd isotopes Cd99-109 have been performed with the ISOLTRAP mass spectrometer at ISOLDE/CERN, all with relative mass uncertainties below 310-8. A new mass evaluation has been performed. The mass of Cd99 has been determined for the first time, which extends the region of accurately known mass values toward the doubly magic nucleus Sn100. The implication of the results on the reaction path of the rp process in stellar x-ray bursts is discussed. In particular, the uncertainty of the abundance and the overproduction created by the rp-process for the mass A=99 are demonstrated by reducing the uncertainty of the proton-separation energy of In100Sp(In100) by a factor of 2.5.

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

2009-09-01

165

Communication: Trapping upconverted energy in neat platinum porphyrin films via an unexpected fusion mechanism  

NASA Astrophysics Data System (ADS)

Direct observation of an unexpected product from excited state fusion of two excited triplet states in platinum octaethylporphyrin is reported. Transient spectroscopy was used to identify the product as a metal centered (d, d) state that decays slowly compared with the rate of fusion. The reaction was demonstrated to be second order with a rate coefficient of kTTF = (5.4 0.4) 10-10 cm3 . s-1. The results contrast with the common assumption that fusion proceeds directly to annihilation via rapid non-radiative deactivation of the products. Following visible photo-excitation, the fusion process results in energetic upconversion of the incident photons stored in the higher energy (d, d) state at irradiances below the threshold for multi-photon absorption.

Hinke, Jonathan A.; Pundsack, Tom J.; Luhman, Wade A.; Holmes, Russell J.; Blank, David A.

2013-09-01

166

Adhesion to the yeast cell surface as a mechanism for trapping pathogenic bacteria by Saccharomyces probiotics.  

PubMed

Recently, much attention has been given to the use of probiotics as an adjuvant for the prevention or treatment of gastrointestinal pathology. The great advantage of therapy with probiotics is that they have few side effects such as selection of resistant bacteria or disturbance of the intestinal microbiota, which occur when antibiotics are used. Adhesion of pathogenic bacteria onto the surface of probiotics instead of onto intestinal receptors could explain part of the probiotic effect. Thus, this study evaluated the adhesion of pathogenic bacteria onto the cell wall of Saccharomyces boulardii and Saccharomyces cerevisiae strains UFMG 905, W303 and BY4741. To understand the mechanism of adhesion of pathogens to yeast, cell-wall mutants of the parental strain of Saccharomyces cerevisiae BY4741 were used because of the difficulty of mutating polyploid yeast, as is the case for Saccharomyces cerevisiae and Saccharomyces boulardii. The tests of adhesion showed that, among 11 enteropathogenic bacteria tested, only Escherichia coli, Salmonella Typhimurium and Salmonella Typhi adhered to the surface of Saccharomyces boulardii, Saccharomyces cerevisiae UFMG 905 and Saccharomyces cerevisiae BY4741. The presence of mannose, and to some extent bile salts, inhibited this adhesion, which was not dependent on yeast viability. Among 44 cell-wall mutants of Saccharomyces cerevisiae BY4741, five lost the ability to fix the bacteria. Electron microscopy showed that the phenomenon of yeast-bacteria adhesion occurred both in vitro and in vivo (in the digestive tract of dixenic mice). In conclusion, some pathogenic bacteria were captured on the surface of Saccharomyces boulardii, Saccharomyces cerevisiae UFMG 905 and Saccharomyces cerevisiae BY4741, thus preventing their adhesion to specific receptors on the intestinal epithelium and their subsequent invasion of the host. PMID:22580913

Tiago, F C P; Martins, F S; Souza, E L S; Pimenta, P F P; Araujo, H R C; Castro, I M; Brando, R L; Nicoli, Jacques R

2012-09-01

167

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

168

Statistical mechanics of non-Markovian exclusion processes  

E-print Network

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

Concannon, Robert James

2014-06-28

169

Faculty Position in Mechanical Engineering Water Conservation in Industrial Processes  

E-print Network

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

170

Transprocessing: A Proposed Neurobiological Mechanism of Psychotherapeutic Processing  

PubMed Central

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

Bota, Robert G.

2014-01-01

171

WASTE PROCESSING: THE STATUS OF MECHANICAL AND BIOLOGICAL TREATMENT  

Microsoft Academic Search

The term 'Mechanical and Biological' (MBT) is commonly used to describe a hybrid process which combines Mechanical techniques used to sort municipal solid waste (MSW) and Biological techniques used to stabilise the organic fraction of it. Recently, these concepts have attracted considerable attention and have received support from public officials and environmental organisations. MBT is a step within the whole

Monique Kallassy; Boris Efremenko; Martin Champel

172

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.

173

Mechanization and automation of production processes in turbine building  

NASA Astrophysics Data System (ADS)

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

Slobodyanyuk, V. P.

1984-02-01

174

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

SciTech Connect

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

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

1997-03-01

175

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

176

Thermo-Mechanical Processing Parameters for the INCONEL ALLOY 740  

SciTech Connect

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

Ludtka, G.M.; Smith, G.

2007-11-19

177

A Process Management Tool Supporting Component-Based Process Development and Hierarchical Management Mechanism  

Microsoft Academic Search

How to develop the software process models that satisfy the organization's standards and the characteristics of software projects, and improve it continuously, is difficulty for software organizations. A process management tool named JBPM (Jade Bird Process Management) proposes a good solution for this issue. JBPM supports component based process development and hierarchical management mechanism which is illuminated by CMM. In

Yasha Wang; Dongni Li; Xiaoyang He

2005-01-01

178

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

179

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

180

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

181

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

182

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

183

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

184

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

Code of Federal Regulations, 2014 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...

2014-07-01

185

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

186

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

187

Mechanisms of genome instability induced by RNA-processing defects.  

PubMed

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

Chan, Yujia A; Hieter, Philip; Stirling, Peter C

2014-06-01

188

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

189

Processing dependence of mechanical properties of metallic glass nanowires  

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

190

A Contact-Mechanics-Based Model for General Rough Pads in Chemical Mechanical Polishing Processes  

E-print Network

, a general rough-pad model is proposed for the chemical mechanical polishing CMP process. The proposed rough-pad also be used as a CMP pad design tool for improving dishing and erosion. © 2009 The Electrochemical be used to assist in optimizing the CMP process to improve dishing and erosion. As the polishing pads play

Cai, Wei

191

Processing, reliability and integration issues in chemical mechanical planarization  

NASA Astrophysics Data System (ADS)

Global planarization is one of the major demands of the semiconductor industry. Chemical mechanical polishing (CMP) is the planarization method of choice use to achieve the required stringent tolerances essential for successful fabrication of next generation Integrated Circuits (IC). The predominant reason for CMP defects is the shear and normal stresses during polishing to which the material is subjected. Understanding the process of CMP and factor that contribute to overall stress addition during polishing requires an approach that encompasses all the four major categories of variables, namely: (a) machine parameters, (b) material properties, (c) polishing pad characteristics, and (d) polishing slurry performance. In this research, we studied the utilized in-situ technique involving acoustic emission (AE) signal monitoring and coefficient of friction (COF) monitoring using a CETR(TM) Bench Top CMP Tester to evaluate the impact of variation in machine parameters on the CMP process. The mechanical and tribological properties of different candidate materials have been evaluated bring potential challenges in their integration to the fore. The study also involves destructive and non destructive testing of polishing pads performed for characterization and optimization of polishing pad architecture. Finally, the investigation concludes proposing novel nanoparticle CMP slurry which has a predominant chemical component in its polishing mechanism. It was found that the decrease in the mechanical shear and normal loading by: (a) operating the process in the low stress regime, (b) using potential materials that are mechanically stronger, (c) using polishing pads with lesser variation in specific gravity and with a surface that is has its mechanical properties fine tuned to those of the wafer, and (d) deploying polishing slurry with a significant chemical component mechanical removal, are some of the approaches that can be employed to meet the future challenges of the CMP process and reduce the defect associated with it.

Zantye, Parshuram B.

192

Functional characterization of TRAP1-like protein involved in modulating fibrotic processes mediated by TGF-?/Smad signaling in hypertrophic scar fibroblasts.  

PubMed

The transforming growth factor-?1 (TGF-?)-mediated signaling pathway is believed to be closely associated with wound healing and scar formation, in which TRAP1-like protein (TLP) plays a role in regulating the balance of Smad2 vs. Smad3 signaling. Our previous study revealed the relation between TLP and collagen synthesis in normal human skin fibroblasts. Here, we present a detailed analysis of the effects of TLP on the process of hypertrophic scar formation and contraction. To explore and verify a contribution of TLP to the pathological mechanism of hypertrophic scar fibroblasts (HSFb), we constructed lentiviral vectors that either overexpressed TLP or encoded small hairpin RNAs (shRNAs) targeting TLP, then we transfected them into HSFb. TLP knockdown in HSFb resulted in reduced levels of cell contraction, type I and type III collagen mRNA transcripts and protein expression, and higher levels of fibronectin (FN) compared to control groups. In addition, knockdown of TLP promoted the phosphorylation of Smad3 but repressed Smad2 and Erk-1/2 phosphorylation in human hypertrophic scar fibroblasts compared to control groups. The reduction of TLP did not interfere with HSF proliferative ability, but exogenous TLP cooperated with TGF-?1 to increase cell viability. Together, our findings demonstrate evidence for a contribution of TLP expression in hypertrophic scar formation and contraction. PMID:25655281

Wang, X; Chu, J; Wen, C J; Fu, S B; Qian, Y L; Wo, Y; Wang, C; Wang, D R

2015-03-15

193

Hemispheric Differences in the Recruitment of Semantic Processing Mechanisms  

ERIC Educational Resources Information Center

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

Kandhadai, Padmapriya; Federmeier, Kara D.

2010-01-01

194

Internet Auction Processes and Mechanisms Timothy L. Y. Leung  

E-print Network

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

Knottenbelt, William J.

195

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

196

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

Code of Federal Regulations, 2010 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...

2010-07-01

197

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

198

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

199

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

200

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

201

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

202

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

203

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

204

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

Code of Federal Regulations, 2014 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...

2014-07-01

205

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

Code of Federal Regulations, 2014 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...

2014-07-01

206

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

E-print Network

carnivorous plants Dionaea muscipula and Aldrovanda vesiculosa Simon Poppinga1 and Marc Joyeux2,* 1 Plant July 2011; revised manuscript received 9 September 2011; published 24 October 2011) The carnivorous. For example, the millimeter-sized underwater suction traps of carnivorous Utricularia species (bladderworts

207

Evaluation of Electrical Characteristics and Trap-State Density in Bottom-Gate Polycrystalline Thin Film Transistors Processed with High-Pressure Water Vapor Annealing  

Microsoft Academic Search

This paper discusses electrical characteristics and trap-state density in polycrystalline silicon (poly-Si) used in bottom-gate poly-Si thin film transistors (TFTs) processed with high-pressure water vapor annealing (HWA). The threshold voltage uniformity of the HWA-processed TFTs is improved by 42% for N-channel and 38% for P-channel TFTs in terms of standard deviation, and carrier mobility is enhanced by 10% or greater

Masafumi Kunii

2006-01-01

208

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

209

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

210

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

211

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

212

Two-Dimensional Patterning by a Trapping/Depletion Mechanism: The Role of TTG1 and GL3 in Arabidopsis Trichome Formation  

PubMed Central

Trichome patterning in Arabidopsis serves as a model system to study how single cells are selected within a field of initially equivalent cells. Current models explain this pattern by an activatorinhibitor feedback loop. Here, we report that also a newly discovered mechanism is involved by which patterning is governed by the removal of the trichome-promoting factor TRANSPARENT TESTA GLABRA1 (TTG1) from non-trichome cells. We demonstrate by clonal analysis and misexpression studies that Arabidopsis TTG1 can act non-cell-autonomously and by microinjection experiments that TTG1 protein moves between cells. While TTG1 is expressed ubiquitously, TTG1YFP protein accumulates in trichomes and is depleted in the surrounding cells. TTG1YFP depletion depends on GLABRA3 (GL3), suggesting that the depletion is governed by a trapping mechanism. To study the potential of the observed trapping/depletion mechanism, we formulated a mathematical model enabling us to evaluate the relevance of each parameter and to identify parameters explaining the paradoxical genetic finding that strong ttg1 alleles are glabrous, while weak alleles exhibit trichome clusters. PMID:18547143

Bouyer, Daniel; Schnittger, Arp; Pesch, Martina; Wester, Katja; Balkunde, Rachappa; Timmer, Jens; Fleck, Christian; Hlskamp, Martin

2008-01-01

213

Process Mechanics of Low Plasticity Burnishing of Nitinol Alloy  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

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 whic...

Dadhich, Naresh

2012-01-01

215

Mass measurements in the vicinity of the r p-process and the {nu} p-process paths with the Penning trap facilities JYFLTRAP and SHIPTRAP  

SciTech Connect

The masses of very neutron-deficient nuclides close to the astrophysical r p- and {nu} p-process paths have been determined with the Penning trap facilities JYFLTRAP at JYFL/Jyvaeskylae and SHIPTRAP at GSI/Darmstadt. Isotopes from yttrium (Z=39) to palladium (Z=46) have been produced in heavy-ion fusion-evaporation reactions. In total, 21 nuclides were studied, and almost half of the mass values were experimentally determined for the first time: {sup 88}Tc, {sup 90-92}Ru, {sup 92-94}Rh, and {sup 94,95}Pd. For the {sup 95}Pd{sup m}, (21/2{sup +}) high-spin state, a first direct mass determination was performed. Relative mass uncertainties of typically {delta}m/m=5x10{sup -8} were obtained. The impact of the new mass values has been studied in {nu} p-process nucleosynthesis calculations. The resulting reaction flow and the final abundances are compared with those obtained with the data of the Atomic Mass Evaluation 2003.

Weber, C.; Elomaa, V.-V.; Aeystoe, J.; Eronen, T.; Hager, U.; Hakala, J.; Jokinen, A.; Kankainen, A.; Moore, I. D.; Penttilae, H.; Rahaman, S.; Rissanen, J.; Saastamoinen, A.; Sonoda, T. [Department of Physics, University of Jyvaeskylae, FI-40014 Jyvaeskylae (Finland); Ferrer, R. [Institut fuer Physik, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany); Froehlich, C. [Enrico Fermi Institute, Department of Astronomy and Astrophysics, University of Chicago, Chicago, Illinois 60637 (United States); Ackermann, D.; Block, M.; Dworschak, M.; Herfurth, F. [GSI-Darmstadt mbH, D-64291 Darmstadt (Germany)] (and others)

2008-11-15

216

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

217

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

218

Description of the deformation process under thermo-mechanical fatigue  

Microsoft Academic Search

Purpose: The main problem addressed in the paper is the description of a deformation process under the conditions of mechanical and thermal interactions. Design\\/methodology\\/approach: The mathematical modelling has been used to describe the stress-strain behaviour of materials. The method of fatigue testing has been adopted to determine experimentally stress-strain characteristics. The method based on the long term own experience in

J. Okrajni; A. Marek; G. Junak

2007-01-01

219

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

PubMed

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

Segura-Aguilar, Juan; Kostrzewa, Richard M

2015-04-01

220

Mechanical and tribological properties of ion beam-processed surfaces  

NASA Astrophysics Data System (ADS)

A variety of surface modification and surface coating techniques are currently used in industry to modify the near-surface mechanical properties that influence the friction and wear behavior of metals, metallic alloys, ceramics, and polymers. Near-surface mechanical properties such as hardness and fracture toughness of a coating-substrate system can be tailored economically without changing the bulk properties of the system. 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. (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. Wear mechanisms that occurred in implanted and unimplanted surfaces tested against AIS152100 steel were determined to be adhesive, abrasive, and third body wear. 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. The wear morphology of the coatings that were tested against a ruby slider suggested that abrasive wear, brittle fracture, and third body wear are the mechanisms by which loss of material can occur.

Kodali, Padma

221

Examining sediment transport processes within two submarine canyons off coastal southern California using sediment trap arrays and naturally-occurring radionuclides  

NASA Astrophysics Data System (ADS)

The transport of sediment was examined in two submarine canyons (Mugu and Hueneme) located in southern California, just south of Ventura. Two vertically-separated sediment traps were deployed in each canyon for approximately 6 months. The mooring in Mugu Canyon, which presumably receives most of its sediment load from the Calleguas Creek, was deployed in 180m of water and the two sediment traps were positioned 30m and 60m above the sea floor. Huemene Canyon lies just south of the Santa Clara River and in this system the sediment traps were also located at 30m and 60m above the sea floor on a mooring deployed in 190m of water. As has been shown previously, the offshore transport of sediment from land in this region occurs mostly during episodic winter storm events that can deliver sediment as distinct pulses that are usually correlated to heightened precipitation events. Naturally-occurring radionuclides were measured in discrete time-stamped intervals of the four extruded sediment trap columns to obtain time-series flux estimates that can provide insight into particle scavenging and removal processes. In general, 226Ra fluxes (1-31 dpm g-1 d-1) are highly correlated (R2 up to 95) to total mass fluxes (1-13 g m-2 d-1), while excess xs210Pb:total mass fluxes reveal substantial additional input/removal processes. An xs234Th-based geochronology (0.4cm d-1) of the Mugu Canyon upper sediment trap is consistent with the observed (80cm in 190 d) sedimentation rate. Our results suggest that in these two submarine canyon systems, the supply of sediment consists of two components (allochthonous and reworked/resuspended) that can be tracked using naturally-occurring radionuclides.

Swarzenski, P. W.; Xu, J.

2008-12-01

222

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

223

Nano trap for polar molecules  

NASA Astrophysics Data System (ADS)

A new ac/dc monopole trap for neutral polar particles, introduced and explored by Blmel (2011 Phys. Rev. A 83 045402 and 2011 Eur. Phys. J. D 64 85-101), is significantly advanced in several directions. (1) Previously shown to work only for polar classical particles and polar macro-molecules, the trap is shown to work for polar diatomic molecules. (2) A homogeneous electric field, optionally switched on for improved stability in the angular direction, leads to stable trapping in higher order stability regions of the Mathieu equation. (3) Based on the Floquet formalism, analytical and numerical calculations are presented that show that the trap is quantum mechanically stable. (4) Definition and derivation of a quantum pseudo-potential allow a qualitative understanding of the quantum trapping mechanism. (5) It is shown that the proposed ac/dc trap may be realized experimentally using currently available scanning tunnelling microscopy technology.

Blmel, R.

2012-07-01

224

Trapping Coyotes  

E-print Network

Coyotes cause millions of dollars of damage yearly to livestock and crops in Texas. The leaflet explains coyote habits and the types of trap set, such as scent posts, dirt holes, and trail and carcass sets. The variety of traps available and how...

Texas Wildlife Services

2008-04-15

225

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

NASA Astrophysics Data System (ADS)

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

Ciurea, Magdalena Lidia; Lazanu, Sorina

2014-10-01

226

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

SciTech Connect

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

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

2014-10-06

227

Antihydrogen Trapped  

NASA Astrophysics Data System (ADS)

In 2010 the ALPHA collaboration succeeded in trapping antihydrogen atoms for the first time.ootnotetext``Trapped antihydrogen,'' G.B. Andresen et al., Nature 468, 673 (2010) Stored antihydrogen promises to be a unique tool for making high precision measurements of the structure of this first anti-atom. Achieving this milestone presented several substantial experimental challenges and this talk will describe how they were overcome. The unique design features of the ALPHA apparatus will be explained.ootnotetext``A Magnetic Trap for Antihydrogen Confinement,'' W. Bertsche et al., Nucl. Instr. Meth. Phys. Res. A 566, 746 (2006) These allow a high intensity positron source and an antiproton imaging detector similar to the one used in the ATHENAootnotetext``Production and detection of cold antihydrogen atoms,'' M.Amoretti et al., Nature 419, 456 (2002). experiment to be combined with an innovative magnet design of the anti-atom trap. This seeks to minimise the perturbations to trapped charged particles which may cause particle loss and heating.ootnotetext``Antihydrogen formation dynamics in a multipolar neutral anti-atom trap.'' G.B. Andresen et al., Phys. Lett. B 685, 141 (2010) The diagnostic techniques used to measure the diameter, number, density, and temperatures of both plasmas will be presented as will the methods developed to actively compress and cool of both plasma species to sizes and temperaturesootnotetext``Evaporative Cooling of Antiprotons to Cryogenic Temperatures,'' G.B. Andresen et al. Phys. Rev. Lett 105, 013003 (2010)^,ootnotetext``Compression of Antiproton Clouds for Antihydrogen Trapping,'' G. B. Andresen et al. Phys. Rev. Lett 100, 203401 (2008)^,ootnotetext``Autoresonant Excitation of Antiproton Plasmas,'' G.B. Andresen et al., Phys. Rev. Lett. 106, 025002 (2011) where trapping attempts with a reasonable chance of success can be tried. The results of the successful trapping experiments will be outlined as well as some subsequent experiments to improve the trapping rate and storage time.

Bowe, Paul D.

2011-06-01

228

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

229

Quantum measurements and new concepts for experiments with trapped ions  

E-print Network

Experiments with individual trapped ions are ideally suited to investigate fundamental issues of quantum mechanics such as the measurement process. At the same time electrodynamically trapped ions have been used with great success to demonstrate quantum logic operations and are a candidate for scalable quantum computing. In this article a brief introduction is given to the basic steps that constitute a quantum measurement; in particular, measurements on single quantum systems are considered. Then experiments with single Yb+ are reviewed demonstrating the quantum Zeno paradox, as well as an experiment where an adaptive algorithm for quantum state estimation of qubits was implemented. In the last section of this article -- devoted to experiments and new ideas related to quantum information processing (QIP) with trapped ions -- the realization of various quantum channels using a hyperfine qubit of Yb+ is briefly discussed. Then a concept for QIP with trapped ions is reviewed where rf or microwave radiation is us...

Wunderlich, C; Balzer, Christoph

2003-01-01

230

Diffusion Processes in Phase Spaces and Quantum Mechanics  

E-print Network

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

E. M. Beniaminov

2008-03-18

231

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

232

Processing mechanics of alternate twist ply (ATP) yarn technology  

NASA Astrophysics Data System (ADS)

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

Elkhamy, Donia Said

233

Quantum Mechanical Insights into Biological Processes at the Electronic Level  

NASA Astrophysics Data System (ADS)

The realm of biology is always governed by underlying electronic effects. These effects are often treated implicitly and may go nearly unnoticed in classical biomolecular simulations, such as Monte Carlo or molecular dynamics. It is important to remember, however, that these classical methods always operate on the single, ground electronic potential energy surface (PES). Furthermore, classical methods assume the classical behavior of the atomic nuclei, and thus rely on the so-called Born-Oppenheimer approximation (BAO) heavily used in quantum mechanics, as discussed in detail below. Due to the BAO, the ground PES can be obtained by finding the optimal electronic solution for every position of stationary classical nuclei. The combined electronic and nuclear energy as a function of nuclear coordinates in the PES. The Born-Oppenheimer PES is usually very close to the chemical reality. Parameters of classical force fields are optimized to reproduce this ground PES, either calculated quantum mechanically or derived from the experiment. Thus, electronic structure is always an active player in classical simulations through the parameters of the force field in use. However, when it comes to the assessment of the mechanism of a biochemical reaction that involves breaking and forming of covalent bonds, quantum mechanics is an almost exclusive reliable approach, with a prominent classical exception being the empirical valence bond method. Furthermore, there is a large class of biological processes that simply cannot be assessed without explicit quantum mechanical treatment. An obvious example is electron transfer in enzymes or DNA that plays a pivotal role in every oxidation or reduction event in living cells.

Alexandrova, Anastassia N.

234

Steam trap monitor  

DOEpatents

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

Ryan, M.J.

1987-05-04

235

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

236

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. Prez

2014-06-11

237

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

238

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.

Mller, Thomas; Knoll, Alois

2011-03-01

239

Processing, mechanical properties and microfractography of polymer concrete composite material  

SciTech Connect

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

Kim, K.

1986-01-01

240

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

PubMed

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

Green, Jonathan

2015-01-01

241

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

242

Rotating Saddle Paul Trap.  

ERIC Educational Resources Information Center

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

Rueckner, Wolfgang; And Others

1995-01-01

243

Determinants and mechanisms of attentional modulation of neural processing.  

PubMed

This review contrasts the most-studied variety of attention, visuospatial attention, with several types of nonspatial visual attention. We: 1) discuss the manner in which spatial and nonspatial varieties of attention are experimentally defined, and the ecological validity of the paradigms in which they are studied, 2) review and compare differing effects of spatial and nonspatial attention on neural processing, 3) discuss the manner in which attention operates within the framework of an anatomical visual hierarchy, as well as 4) how attention relates to the temporal dynamics of visual processing, 5) describe cellular circuits and physiological processes that appear to be involved in attention effects, 6) discuss the relationship of attentional physiology to the perceptual and cognitive effects of attention, and 7) consider the strengths and limitations of several current models of selective attention. Throughout, we attempt to integrate the findings of monkey and human studies whenever possible. We have three main conclusions. First, two models, the Neural Specificity Model of Harter and colleagues and the Feature Similarity Gain Model of Treue and colleagues best incorporate findings in relation to both spatial and nonspatial varieties of attention. Significantly, these models explicitly note that the specific neuronal components used in attentional modulation of processing are flexible and determined by task demands. Second, current evidence also provides strong bases for deriving testable hypotheses about the specific brain mechanisms utilized by attention. Cellular processes, brain circuits and neurotransmitter components can and should be incorporated into our models of attention. Finally, it is increasingly evident that we can and should analyze temporal patterns of attentional modulation, both within and across brain areas. These patterns provide critical information on the dynamics of attention. PMID:11333209

Schroeder, C E; Mehta, A D; Foxe, J J

2001-05-01

244

Charge motion and trapping in insulators: surface and bulk effects  

Microsoft Academic Search

The electrical currents that flow in and on insulators are small, but they may be important in applications and they may indicate the mechanism of carrier motion. The processes which come into play include mobility and ionization, trapping and detrapping, and injection and blocking. Some of these phenomena are intrinsic to the material, while others depend on the amount and

H. J. Wintle

1999-01-01

245

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

246

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

247

Formal mechanization of device interactions with a process algebra  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

248

Processing and mechanical properties of HA/UHMWPE nanocomposites.  

PubMed

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

Fang, Liming; Leng, Yang; Gao, Ping

2006-07-01

249

Medial Efferent Mechanisms in Children with Auditory Processing Disorders  

PubMed Central

Auditory processing disorder (APD) affects about 25% of children. However, the nature of this disorder is poorly understood. Children with APD typically have difficulties in complex listening situations. One mechanism thought to aid in listening-in-noise is the medial olivocochlear (MOC) inhibition. The purpose of this review was to critically analyze the published data on MOC inhibition in children with APD to determine whether the MOC efferents are involved in these individuals. The otoacoustic emission (OAE) methods used to assay MOC reflex were examined in the context of the current understanding of OAE generation mechanisms. Relevant literature suggests critical differences in the study population and OAE methods. Variables currently known to influence MOC reflex measurements, for example, middle-ear muscle reflexes or OAE signal-to-noise ratio, were not controlled in most studies. The use of potentially weaker OAE methods and the remarkable heterogeneity across studies does not allow for a definite conclusion whether or not the MOC reflex is altered in children with APD. Further carefully designed studies are needed to confirm the involvement of MOC efferents in APD. Knowledge of efferent functioning in children with APD would be mechanistically and clinically beneficial. PMID:25386132

Mishra, Srikanta K.

2014-01-01

250

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

251

Hydrocarbon traps along Louisiana offshore  

SciTech Connect

A compilation of potential hydrocarbon trap types has been assembled for the Louisiana offshore, from coastal plain to abyssal plain. These potential traps are listed according to paleophysiographic provinces: coastal plain, shelf, shelf break, upper slope, middle slope, lower slope, and abyssal plain. Characteristics of each trap type are tabulated. The characteristics include tectonics, regional and local sedimentation rates and types, position within an evolving sequence as determined by sequence stratigraphy, duration of reservoir and/or trap creation, and sea level position. Regional geologic processes, such as salt tectonics, and approximate rates at which they operate are also listed.

Lowrie, A.; Sullivan, N.

1989-03-01

252

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

253

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

NASA Astrophysics Data System (ADS)

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.

Kim, Yeong E.; Passell, Thomas O.

2006-02-01

254

Novel designs for Penning ion traps  

E-print Network

We present a number of alternative designs for Penning ion traps suitable for quantum information processing (QIP) applications with atomic ions. The first trap design is a simple array of long straight wires which allows easy optical access. A prototype of this trap has been built to trap Ca+ and a simple electronic detection scheme has been employed to demonstrate the operation of the trap. Another trap design consists of a conducting plate with a hole in it situated above a continuous conducting plane. The final trap design is based on an array of pad electrodes. Although this trap design lacks the open geometry of the traps described above, the pad design may prove useful in a hybrid scheme in which information processing and qubit storage take place in different types of trap. The behaviour of the pad traps is simulated numerically and techniques for moving ions rapidly between traps are discussed. Future experiments with these various designs are discussed. All of the designs lend themselves to the construction of multiple trap arrays, as required for scalable ion trap QIP.

Authors J. R. Castrejon-Pita; H. Ohadi; D. R. Crick; D. F. A. Winters; D. M. Segal; R. C. Thompson

2006-03-22

255

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

NASA Astrophysics Data System (ADS)

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

Park, Mi-Ran

256

Deep hole trapping effects in the degradation mechanisms of 6.52 nm thick gate-oxide PMOSFETs  

Microsoft Academic Search

Hot-carrier (HC) degradation in PMOSFETs with thin (Tox=2 nm) and thick (6.5 nm) gate-oxides are investigated as they show very different damage mechanisms when electrons or holes are involved. It is shown for the first time that hot-hole currents are now directly measured through a thermionic gate-current in Tox=6.5 nm devices which is limited to hole tunneling currents in high

A Bravaix; D Goguenheim; N Revil; E Vincent

2004-01-01

257

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.

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

2014-01-01

258

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

259

Ion traps fabricated in a CMOS foundry  

SciTech Connect

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.; Ram, R. J. [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Eltony, A. M.; Chuang, I. L. [Center for Ultracold Atoms, Research Laboratory of Electronics and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Bruzewicz, C. D.; Sage, J. M., E-mail: jsage@ll.mit.edu; Chiaverini, J., E-mail: john.chiaverini@ll.mit.edu [Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02420 (United States)

2014-07-28

260

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

261

INSECT TRAP  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

262

On the elementary processes of protein crystallization: Bond selection mechanism  

NASA Astrophysics Data System (ADS)

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

Nanev, Christo N.

2014-09-01

263

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

264

Coherence in Microchip Traps  

E-print Network

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

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

2004-04-22

265

Switching Oxide Traps  

NASA Technical Reports Server (NTRS)

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

Oldham, Timothy R.

2003-01-01

266

Laser cooling of trapped ions Jurgen Eschner  

E-print Network

Laser cooling of trapped ions Jurgen Eschner Institut fu r Experimentalphysik, Universita Received November 12, 2002; revised manuscript received December 4, 2002 Trapped and laser-cooled ions, and for quantum information processing. Therefore laser cooling of trapped ions is reviewed, the current state

Blatt, Rainer

267

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

268

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

PubMed

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

Silva, Rafael Menezes; Carvalho, Vincius Xavier Mattar de; Dumont, Vitor Csar; Santos, Maria Helena; Carvalho, Ana Mrcia Macedo Ladeira

2015-01-01

269

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

270

Isolating Quantum Mechanical Processes in Billiard Ball Collisions  

NASA Astrophysics Data System (ADS)

The few-body problem remains an important unsolved Physics problem. In atomic collisions, while the interactions are well understood, the problem is still not solvable. However, at intermediate or high energies, the contributions to ionization from binary collisions may be isolated and studied directly. Final-state interactions between the charged projectile and the ejected electron following ionization have been calculated to give cusp-like structures in the differential ionization cross section when the projectile and ejected electron emerge in the same direction with the same speed.(See for example, M.W. Lucas, K.F. Man and W. Steckelmacher, in Lecture Notes in Physics vol. 213, ed K.O. Groeneveld, W. Meckbach and I. Sellin (Berlin: Springer), p1 (1984).) These processes are known as ``capture to the continuum" for a positive projectile and "anticapture to the continuum" for a negative projectile.(L.H. Thomas, Proc. Roy. Soc. A114 561 (1927).)^,(See J.S. Briggs, Comments At. Mol. Phys. 23, 175 (1989), for more recent work.) The projectile can transfer significant momentum in these collisions and two or more outgoing particles can significant velocity after the collision which cannot be accounted for theoretically. Therefor experimental measurements can provide guidance for further theoretical development. We have reported the first experimental evidence of electron anticapture to the continuum at about 45^circ in e^- - Ar scattering at 1000 eV. This double-binary collision mechanism (the electron scattering analogue of the Thomas forward peak in ion-atom scattering) has been isolated by studying correlated projectile and ejected electrons traveling in the same direction following e^--Ar collisions. The cross section for this process rises as 45^circ is approached, but drops precipitously at about 45^circ. This dip is the signature of anticapture to the continuum for negative projectiles and corresponds to a zero Coulomb density of states factor at 45^circ. In addition, a significant departure from the Rutherford formula have been found for the one-electron differential cross section at large scattering angles.

Golden, D. E.

1997-10-01

271

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

NASA Astrophysics Data System (ADS)

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

Mudhivarthi, Subrahmanya R.

272

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

273

An Analysis of the ChemicalMechanical Polishing Process \\Lambda  

E-print Network

Mises stress on the wafer surface is considered in [7]; mechanical properties of the slurry particles, 1998 Abstract We examine the non­uniform wear of the wafer and the pad in the Chemical Mechanical Polishing of wafers in the semiconductor industry. We model the pad as a set of springs in order to get

274

An Optimal Dynamic Mechanism for Multi-Armed Bandit Processes  

Microsoft Academic Search

We consider the problem of revenue-optimal dynamic mechanism design in settings where agents' types evolve over time as a function of their (both public and private) experience with items that are auctioned repeatedly over an infinite horizon. A central question here is under- standing what natural restrictions on the environment permit the design of optimal mechanisms (note that even in

Sham M. Kakade; Ilan Lobel; Hamid Nazerzadeh

2010-01-01

275

Extrinsic and intrinsic charge trapping at the graphene/ferroelectric interface.  

PubMed

The interface between graphene and the ferroelectric superlattice PbTiO3/SrTiO3 (PTO/STO) is studied. Tuning the transition temperature through the PTO/STO volume fraction minimizes the adorbates at the graphene/ferroelectric interface, allowing robust ferroelectric hysteresis to be demonstrated. "Intrinsic" charge traps from the ferroelectric surface defects can adversely affect the graphene channel hysteresis and can be controlled by careful sample processing, enabling systematic study of the charge trapping mechanism. PMID:25134063

Yusuf, M Humed; Nielsen, Bent; Dawber, M; Du, X

2014-09-10

276

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

277

MODEL PREDICTIVE CONTROL OF A MECHANICAL PULP BLEACHING PROCESS  

E-print Network

of controlling a real- world delay-time system application, the pulp bleaching process at Irving Paper Ltd of controlling the pulp bleaching process at the Irving Paper mill. This would improve the pulp quality the consumption of the bleaching chemicals. In section 2 of this paper the bleaching process and its dynamics

Taylor, James H.

278

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; Kroo, Bernhard

2013-04-01

279

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

280

EFFECT OF TEMPERATURE ON PAD CONDITIONING PROCESS DURING CHEMICAL-MECHANICAL PLANARIZATION  

Microsoft Academic Search

Pad conditioning process is one of the crucial process steps during chemical-mechanical planarization (CMP). Pad needs to be conditioned at regular time intervals to regenerate a rough surface in order to maintain consistent and optimum polishing process. Inconsistent pad conditioning directly affects the repeatability of the process outcome. Thus, it is essential to study the factors influencing the conditioning process.

S. Raghu Mudhivarthi; Norm Gitis; Suresh Kuiry; Michael Vinogradov; Ashok Kumar

281

Dual-Pitch Processing Mechanisms in Primate Auditory Cortex  

E-print Network

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

Bendor, Daniel

282

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

283

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

SciTech Connect

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

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

2011-12-15

284

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

285

Steam trap monitor  

DOEpatents

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

Ryan, Michael J. (Plainfield, IL)

1988-01-01

286

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...

287

Mechanisms of Verbal Morphology Processing in Heritage Speakers of Russian  

ERIC Educational Resources Information Center

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

Romanova, Natalia

2008-01-01

288

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.

289

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

290

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

291

Processing and mechanical characterization of lightweight polyurethane composites  

Microsoft Academic Search

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

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

2003-01-01

292

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

293

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,

294

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

PubMed

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

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

2015-03-01

295

Quantum measurements and new concepts for experiments with trapped ions  

E-print Network

Experiments with individual trapped ions are ideally suited to investigate fundamental issues of quantum mechanics such as the measurement process. At the same time electrodynamically trapped ions have been used with great success to demonstrate quantum logic operations and are a candidate for scalable quantum computing. In this article a brief introduction is given to the basic steps that constitute a quantum measurement; in particular, measurements on single quantum systems are considered. Then experiments with single Yb+ are reviewed demonstrating the quantum Zeno paradox, as well as an experiment where an adaptive algorithm for quantum state estimation of qubits was implemented. In the last section of this article -- devoted to experiments and new ideas related to quantum information processing (QIP) with trapped ions -- the realization of various quantum channels using a hyperfine qubit of Yb+ is briefly discussed. Then a concept for QIP with trapped ions is reviewed where rf or microwave radiation is used instead of laser light for coherent manipulation of a collection of ions. In a suitably modified trap the ions form an artificial ion "molecule" to which the techniques developed in nuclear magnetic resonance and electron spin resonance experiments can be directly applied. Finally, coherent excitation of optical electric quadrupole transitions in Yb+ and Ba+ is reported. In addition, robust Raman cooling of a pair of Ba+ ions is reviewed.

Christof Wunderlich; Christoph Balzer

2004-06-11

296

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

297

A new observation of strain-induced slow traps in advanced CMOS technology with process-induced strain using random telegraph noise measurement  

Microsoft Academic Search

In this paper, the hot-carrier induced oxide trap and its correlation with enhanced degradation in strained CMOS devices have been reported for the first time. First, the ID-RTN (drain current random telegraph noise) has been employed to study the HC stress induced slow oxide traps in strained nMOSFETs and pMOSFETs. Secondly, different behavior of the slow traps in nMOSFET and

M. H. Lin; E. R. Hsieh; S. S. Chung; C. H. Tsai; P. W. Liu; Y. H. Lin; G. H. Ma

2009-01-01

298

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 ...

299

A study on the degradation mechanism of InGaZnO thin-film transistors under simultaneous gate and drain bias stresses based on the electronic trap characterization  

NASA Astrophysics Data System (ADS)

We discuss the device degradation mechanism of amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) under simultaneous gate and drain bias stresses based on the electronic trap characterization results. The transfer curve exhibits an apparent negative shift as the stress time increases, and a formation of hump is observed in the transfer curve after stresses. A notable increase of the frequency dispersion is observed after stresses in both gate-to-drain capacitance-voltage (CGD-VG) and gate-to-source capacitance-voltage (CGS-VG) curves, which implies that the subgap states are generated by simultaneous gate and drain bias stresses, and the damaged location is not limited to the drain side of TFTs. The larger frequency dispersion is observed in CGD-VG curves after stresses in a wider channel device, which implies that the heat is an important factor in the generation of the subgap states under simultaneous gate and drain bias stresses in a-IGZO TFTs. Based on the electronic trap characterization results, we conclude that the impact ionization near the drain side of the device is not a dominant mechanism causing the generation of subgap states and device degradation in a-IGZO TFTs under simultaneous gate and drain bias stresses. The generation of oxygen vacancy-related donor-like traps near the conduction band edge is considered as a possible mechanism causing the device degradation under simultaneous gate and drain bias stresses in a-IGZO TFTs.

Jeong, Chan-Yong; Lee, Daeun; Song, Sang-Hun; In Kim, Jong; Lee, Jong-Ho; Kwon, Hyuck-In

2014-04-01

300

Continuous-Time Quantum Walks and Trapping  

E-print Network

Recent findings suggest that processes such as the electronic energy transfer through the photosynthetic antenna display quantal features, aspects known from the dynamics of charge carriers along polymer backbones. Hence, in modeling energy transfer one has to leave the classical, master-equation-type formalism and advance towards an increasingly quantum-mechanical picture, while still retaining a local description of the complex network of molecules involved in the transport, say through a tight-binding approach. Interestingly, the continuous time random walk (CTRW) picture, widely employed in describing transport in random environments, can be mathematically reformulated to yield a quantum-mechanical Hamiltonian of tight-binding type; the procedure uses the mathematical analogies between time-evolution operators in statistical and in quantum mechanics: The result are continuous-time quantum walks (CTQWs). However, beyond these formal analogies, CTRWs and CTQWs display vastly different physical properties. In particular, here we focus on trapping processes on a ring and show, both analytically and numerically, that distinct configurations of traps (ranging from periodical to random) yield strongly different behaviours for the quantal mean survival probability, while classically (under ordered conditions) we always find an exponential decay at long times.

Elena Agliari; Oliver Muelken; Alexander Blumen

2009-03-19

301

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

PubMed

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

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

2013-05-01

302

ThermoMechanical Model of Solidification Processes with Abaqus  

Microsoft Academic Search

A computational thermo-mechanical model has been developed to simulate the continuous casting of shaped sections, such as used for steel thin slabs. A general form of the transient heat equation including latent-heat from phase transformations such as solidification and other temperature-dependent properties is solved numerically for the temperature field history. The resulting thermal stresses are solved by integrating the highly

Seid Koric; Brian G. Thomas

303

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

304

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

305

Thermo-mechanical phenomena in high speed continuous casting processes  

NASA Astrophysics Data System (ADS)

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

Park, Joong Kil

306

Energy Conservation Thru Steam Trap Surveys and Preventive Maintenance Programs  

E-print Network

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

Boynton, T.; Dewhirst, B.

1980-01-01

307

Anisotropy Mechanism in HDDR Processed NdFeB  

Microsoft Academic Search

\\u000a The Hydrogenation Disproportionation Desorption Recombination (HDDR) process can yield anisotropic and highly coercive NdFeB-type\\u000a powders with energy densities in excess of (BH)max=340 kJ\\/m3. The elucidation of the very unusual phenomenon of texture inducement is of great scientific and technological interest.\\u000a Here, Nd12.5Feba1B6.3 and Nd12.5Feba1Ga0.3Nb0.3B6.3 alloys have been HDDR processed and hydrogen partial pressures and dwell times during disproportionation and recombination

O. Gutfleisch; G. Drazic; C. Mishima; Y. Honkura

308

Study on HydroMechanical Differential Dynamic Turning Process of Tracked Vehicle  

Microsoft Academic Search

The dynamic turning process of tracked vehicle is the transition turning process. The hydro-mechanical differential turning system is the new turning system of tracked vehicle using hydro-mechanical stepless transmission theory and being made up of hydraulic transmission and gear transmission. The hydro-mechanical differential turning theory is analyzed. Basing on turning dynamics and kinematics of tracked vehicle, the simulated model of

Fuyi Cao; Zhili Zhou; Liyou Xu; Mingzhu Zhang

2009-01-01

309

Brain Mechanisms Associated with Top-Down Processes in Perception  

Microsoft Academic Search

Perception arises through an interaction between sensory input and prior knowledge. We propose that at least two brain areas are required for such an interaction: the 'site' where analysis of afferent signals occurs and the 'source' which applies the relevant prior knowledge. In the human brain, functional imaging studies have demonstrated that selective attention modifies activity in early visual processing

Chris Frith; Raymond J. Dolan

1997-01-01

310

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

311

Mechanisms of placement and stability of dry process shotcrete  

Microsoft Academic Search

The knowledge available today in shotcrete technology usually permits the production of strong and durable shotcretes. Unfortunately, very few research projects have focused on the development of the shotcrete process itself. Consequently, the fundamental knowledge on the properties and behaviour of fresh dry-mix shotcrete is very limited. The objective of this research project is thus to develop methods to evaluate

Marc Jolin

1999-01-01

312

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

313

Replisome mechanics: lagging strand events that influence speed and processivity  

PubMed Central

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

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

2014-01-01

314

Electrical, chemical and mechanical processes in water treeing  

Microsoft Academic Search

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

Jean-Pierre Crine

1998-01-01

315

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

316

Micromachined Dust Traps  

NASA Technical Reports Server (NTRS)

Micromachined traps devised to capture dust particles for analysis without contaminating them. Based on micromachined structures retaining particles, rather than adhesives or greases interfering with scanning-electron-microscope analysis or x-ray imaging. Unlike maze traps and traps enmeshing particles in steel wool or similar materials, micromachined traps do not obscure trapped particles. Internal geometries of traps range from simple cones to U-shapes, all formed by etching silicon.

Bearman, Gregory H.; Bradley, James G.

1993-01-01

317

Coherence in Microchip Traps  

E-print Network

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

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

2003-01-01

318

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

319

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

320

Flexible aerogel composite for mechanical stability and process of fabrication  

SciTech Connect

A flexible aerogel and process of fabrication are disclosed. 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, P.R.; Poco, J.F.

1999-10-26

321

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

322

Investigation of the Quenching Mechanism of a Fluorescence Process  

Microsoft Academic Search

The properties and behavior of an electronic excited state were investigated experimentally. The goal was to determine whether, upon interaction with a series of molecules Q, (i.e., 1,2,4-trimethoxybenzene, 1,4-dimethoxybenzene, naphthalene), the fluorescent states of 9,10-dicyanoanthracene and 9-cyanoanthracene are quenched via an electron transfer process. A Stern-Volmer investigation enables evaluation of the rate constant, kq, for quenching of the cyanoanthracene excited

Yi Wang; Debra Egolf; Dennis Kuhl

2010-01-01

323

Efficient thermo-mechanical model for solidification processes  

Microsoft Academic Search

SUMMARY A new, computationally-efficient algorithm has been implemented to solve for thermal stresses, strains, and displacements in realistic solidification processes which involve highly nonlinear consitutitve relations. A general form of the transient heat equation including latent-heat from phase transformations such as solidification and other temperature-dependent properties is solved numerically for the temperature field history. The resulting thermal stresses are solved

Seid Koric; Brian G. Thomas

2006-01-01

324

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

325

Investigation of the Quenching Mechanism of a Fluorescence Process  

NASA Astrophysics Data System (ADS)

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

Wang, Yi; Egolf, Debra; Kuhl, Dennis

2010-04-01

326

On biodiversity conservation and poverty traps.  

PubMed

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

2011-08-23

327

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

328

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

329

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

330

Psychotherapy: Process, mechanisms, and science-practice integration.  

PubMed

I received the Early Career Award from Division 29 and the American Psychological Foundation in 2013. In this article, I briefly review some of my research areas, relevant issues, and future directions. Specifically, I focus on 3 core research areas: psychotherapy process-outcome, psychotherapy integration, and science-practice integration. Within each of these core areas, I also touch on important methodological issues. In addition, I argue that progress in the field will require the application of diverse research methods, spanning basic and applied areas, as well as interdisciplinary and interinstitutional collaboration. (PsycINFO Database Record (c) 2015 APA, all rights reserved). PMID:25602180

Boswell, James F

2015-03-01

331

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

332

Effect on Two-Step Polishing Process of Electrochemical Mechanical Planarization and Chemical-Mechanical Planarization on Planarization  

NASA Astrophysics Data System (ADS)

Chemical-mechanical planarization (CMP) is a technique used for planarizing an overburden film in the fabrication of semiconductor devices by chemical treatment and mechanical abrasion. However, a variety of defects such as dishing of metal interconnects, erosion, delamination, and metal layer peeling are generated by a high down force in CMP. A high down force is required to generate a high material removal rate (MRR), which results in greater defects. To minimize these defects, a new planarization process is used, known as electrochemical mechanical planarization (ECMP), which requires electrochemical and mechanical energies. ECMP first involves using an electrochemical reaction to change the surface on the target material into a passivation film. Then, the passivation film is worn down using a polishing pad or abrasives on the contacted areas of the metal film with the polishing pad under a low down force. The electrochemical energy dissolves the copper solid into copper ions in an aqueous electrolyte on the contacted areas of the metal film and the polishing pad. Therefore, the low-down-force ECMP reduces the defects such as dishing, erosion, delamination and metal layer peeling to a greater degree than a conventional high-down-force CMP. Also, the MRR of the ECMP process is higher than that of the low-down-force CMP process because the MRR of the ECMP process is proportional to current density. However, some residual metal between the dielectric material was generated through the use of a nonconductive polishing pad in the ECMP process. Therefore, the CMP process is required for the final process to remove residual metals. In this research, we investigated a two-step polishing method that consists of ECMP with a nonconductive polishing pad and a conventional CMP process to planarize a micro-patterned wafer for microelectromechanical systems (MEMS). First, the ECMP process using a nonconductive polishing pad removed several tens of micrometers (m) of bulk copper on the patterned wafer over a shorter process time than the copper CMP process only. Then, the residual copper was completely removed through the low-down-force copper CMP process. The total process time and the amount of dishing defects were reduced by applying the two-step polishing method.

Jeong, Sukhoon; Joo, Sukbae; Kim, Hyoungjae; Kim, Sungryul; Jeong, Haedo

2009-06-01

333

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 Mller [3] showed the suitability of some TPEs as polymer processing aids. We investigated the slip velocity of several TPEs against steel, and the slip velocity in a polymeric interface between polyethylene (PE) and TPE by rotational plate-plate rheometry in the Newtonian flow regime. TPEs with lower viscosities showed higher slip velocities against steel. However, the interfacial slip velocities between PE and TPE were found to be viscosity independent. In both cases, the slip velocity was found to be proportional to the applied shear stress.

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

2014-05-01

334

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

335

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 ~210^24 / 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

336

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

337

Implementing a Flexible Compensation Mechanism for Business Processes in Web Service Environment  

E-print Network

of information interaction to a middleware of business process integrations. Nowadays, enterprises are willing to outsource their internal business process as services and make them accessible via the web. In additionImplementing a Flexible Compensation Mechanism for Business Processes in Web Service Environment

Liu, Chengfei

338

MODELING OF PATTERN DEPENDENCIES IN ABRASIVE-FREE COPPER CHEMICAL MECHANICAL POLISHING PROCESSES  

E-print Network

. Introduction In conventional copper CMP processes, polymeric polishing pads, and slurries containing silica]. Abrasive-free copper CMP processes use the same polishing pads and polishing machines used in conventional dependent model for abrasive-free copper chemical mechanical polishing (CMP) processes, and show comparisons

Boning, Duane S.

339

Reduce Steam Trap Failures at Chambers Works  

E-print Network

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.

340

Charge trapping and intermodulation in HEMTs  

Microsoft Academic Search

Charge trapping effects in high electron mobility transistors (HEMTs) are linked to anomalous intermodulation behavior, known as memory effects. This behavior can be observed clearly as changes in intermodulation levels with tone-spacing, and two-tone asymmetry. A Volterra-series analysis of an HEMT with trapping predicts the distortion accurately, and allows an understanding of the mechanisms involved.

James Brinkhoff; Anthony E. Parker

2004-01-01

341

A simple automatic insect light trap  

Microsoft Academic Search

An automatic light trap is described which separates daily catches from a conventional trap into separate containers by means of an electronically controlled rotating delivery funnel. The simple mechanism involved has few moving parts, and can be readily adapted to many service intervals.

N. R. Wrenn

1980-01-01

342

Coupled quantized mechanical oscillators  

E-print Network

The harmonic oscillator is one of the simplest physical systems but also one of the most fundamental. It is ubiquitous in nature, often serving as an approximation for a more complicated system or as a building block in larger models. Realizations of harmonic oscillators in the quantum regime include electromagnetic fields in a cavity [1-3] and the mechanical modes of a trapped atom [4] or macroscopic solid [5]. Quantized interaction between two motional modes of an individual trapped ion has been achieved by coupling through optical fields [6], and entangled motion of two ions in separate locations has been accomplished indirectly through their internal states [7]. However, direct controllable coupling between quantized mechanical oscillators held in separate locations has not been realized previously. Here we implement such coupling through the mutual Coulomb interaction of two ions held in trapping potentials separated by 40 um (similar work is reported in a related paper [8]). By tuning the confining wells into resonance, energy is exchanged between the ions at the quantum level, establishing that direct coherent motional coupling is possible for separately trapped ions. The system demonstrates a building block for quantum information processing and quantum simulation. More broadly, this work is a natural precursor to experiments in hybrid quantum systems, such as coupling a trapped ion to a quantized macroscopic mechanical or electrical oscillator [9-13].

K. R. Brown; C. Ospelkaus; Y. Colombe; A. C. Wilson; D. Leibfried; D. J. Wineland

2011-11-14

343

Survey of trihalomethanes and other volatile chemical contaminants in processed foods by purge-and-trap capillary gas chromatography with mass selective detection.  

PubMed

A limited number of soft drinks, juices, beers, and waters from processed vegetables were analyzed for trihalomethanes (THMs), benzene, and toluene by a modified Environmental Protection Agency (EPA) Method 524.2. The THMs, which include chloroform, bromodichloromethane, dibromochloromethane, and bromoform, are reaction by-products of water disinfection by chlorination. EPA Method 524.2 is a purge-and-trap capillary gas chromatographic method based on mass spectrometric detection which identifies and simultaneously measures purgeable volatile organic compounds in drinking water. Chloroform was present at concentrations ranging from none detected to 94 ng/g in the 44 foods analyzed. Bromoform was not found in any of the products at a detection limit of 0.1 ng/g. Residue levels of the other THMs ranged from none detected to highs of 12 and 2 ng/g for bromodichloromethane and dibromochloromethane, respectively. Benzene residues were typically < 5 ng/g, except for 7 and 9 ng/g in 2 foods. Toluene residues were typically < or = 3 ng/g except for 23, 29, and 75 ng/g in 3 canned foods. PMID:7756854

McNeal, T P; Hollifield, H C; Diachenko, G W

1995-01-01

344

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

345

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

346

Thermoluminescent and dosimetric properties of anion-defective alpha-Al2O3 single crystals with filled deep traps.  

PubMed

Some new experimental results illustrating the effect of deep traps on luminescent and dosimetric properties of anion-defective single crystals of alpha-Al2O3 have been described. It was found that deep traps had an electronic origin. They were filled thanks to the photoionisation of F-centres and their filling was accompanied by the conversion of F-->F+ centres. The experiments revealed an interactive interaction of deep trapping centres. A model taking into account the thermal ionisation of excited states of F-centres was proposed. This model describes the trap filling process and mechanisms of the radio-, photo- and thermoluminescence, TSC and TSEE of the crystals under study. The sensitivity of TLD-500 detectors based on anion-defective alpha-Al2O3 equalised when deep trapping centres were filled. PMID:12382831

Kortov, V S; Milman, I I; Nikiforov, S V

2002-01-01

347

Processing, characterization and mechanical properties of alumina-based nanocomposites  

NASA Astrophysics Data System (ADS)

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

Thomson, Katherine E.

2007-12-01

348

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

349

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

Code of Federal Regulations, 2012 CFR

...205.35 Mechanized claims processing and information retrieval systems; definitions. Section 205.35 through...plan requirements for an automated statewide management information system, conditions for FFP and...

2012-10-01

350

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

Code of Federal Regulations, 2014 CFR

...205.35 Mechanized claims processing and information retrieval systems; definitions. Section 205.35 through...plan requirements for an automated statewide management information system, conditions for FFP and...

2014-10-01

351

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

Code of Federal Regulations, 2013 CFR

...205.35 Mechanized claims processing and information retrieval systems; definitions. Section 205.35 through...plan requirements for an automated statewide management information system, conditions for FFP and...

2013-10-01

352

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

Code of Federal Regulations, 2011 CFR

...205.35 Mechanized claims processing and information retrieval systems; definitions. Section 205.35 through...plan requirements for an automated statewide management information system, conditions for FFP and...

2011-10-01

353

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

354

Evaluating Steam Trap Performance  

E-print Network

EVALUATING STEAM TRAP PERFORMANCE Noel Y Fuller, P.E. Holston Defense Corporation Kingsport, Tennessee ABSTRACT Laboratory tests were conducted on several types of steam traps at Holston Defense Corporation in Kingsport, Tennessee. Data... computer to evaluate overall steam trap economics. This program calculates the EUAC for any steam trap based on 12 input variables including capital, maintenance and steam costs, interest rate and trap life. After determinIng the EUAC, the program...

Fuller, N. Y.

355

Theory of direct scattering, trapping, and desorption in atom-surface collisions Guoqing Fan1  

E-print Network

Theory of direct scattering, trapping, and desorption in atom-surface collisions Guoqing Fan1 and J desorbs in a distribution at equilibrium with the surface temperature. In this paper a scattering theory is developed, using an iterative algorithm and classical mechanics for the collision process, which describes

Manson, Joseph R.

356

Controlled collisions for multi-particle entanglement of optically trapped atoms  

Microsoft Academic Search

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

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

2003-01-01

357

Development of nano-structure CuZr alloys by the mechanical alloying process  

Microsoft Academic Search

CuZr alloys have many applications in electrical and welding industries for their high strength and high electrical and thermal conductivities. These alloys are among age-hardenable alloys with capability of having nano-structure with high solute contents obtainable by the mechanical alloying process. In the present work, CuZr alloys have been developed by the mechanical alloying process. Pure copper powders with different

M. Azimi; G. H. Akbari

2011-01-01

358

Effect of pore structure on gas trapping in porous media  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

359

Steam Trap Application  

E-print Network

, air dryer, pipe coil, process air heater, unit heater Category 3: Gravity draine~, e.g. , chest- Steam Heats a type ironer, belt press, Solid or Slurry chamber dryer, hot plate,platen Indirectly Syphon drained, e.g. , cylinder ironer, cylinder...) 2-Steam heats a gas indirectly (e.g. Air Heater, Dryer~ 3-Steam heats a solid or slurry indirectly. (e.g. Cylinder dryer,Platen) 4-Steam heats a solid directly (e.g. - Autoclave) Steam Pres Generally variable or fluctuating sures at trap due...

Murphy, J. J.

1982-01-01

360

Effective Steam Trap Selection/Maintenance - Its Payback  

E-print Network

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

Garcia, E.

1984-01-01

361

[Processing mechanism of Epimedium fried with suet oil based on absorption and metabolism of flavonoids].  

PubMed

As beneficial traditional Chinese medicine, Epimedium fried with suet oil can enhance the effect of warming kidney yang. Previous literature studies about processing of Epimedium mainly focused on changes in chemical composition and pharmacological effect. From the angle of flavonoids absorption and metabolism, our group innovatively study the processing mechanism of Epimedium based on active component transformation combined with intestinal absorption barrier. The processing effect of fried Epimedium can be divided into two key aspects of " heat" during processing and processing accessories "suet oil". Through continuous three National Natural Science Foundation items, the research group has clarified the scientific connotation of "heat" during processing with ADME, and explains the synergistic mechanism of processing accessories "suet oil" based on self-assembled micelles formation in vivo for the first time. This paper summarizes the research ideas and results of Epimedium processing mechanism of the project team for many years, and discusses the future research direction and content, in order to provide new ideas and new methods for modern Chinese medicine processing mechanism. PMID:24946535

Sun, E; Wei, Ying-Jie; Zhang, Zhen-Hai; Cui, Li; Xu, Feng-Juan; Jia, Xiao-Bin

2014-02-01

362

Design of experiment (DOE) method considering interaction effect of process parameters for optimization of copper chemical mechanical polishing (CMP) process  

Microsoft Academic Search

Chemical mechanical polishing (CMP) has been widely accepted for the metallization of copper interconnection in ultra-large scale integrated circuits (ULSIs) manufacturing. It is important to understand the effect of the process variables such as turntable speed, head speed, down force and back pressure on copper CMP. They are very important parameters that must be carefully formulated to achieve desired the

Nam-Hoon Kim; Min-Ho Choi; Sang-Yong Kim; Eui-Goo Chang

2006-01-01

363

Simulations on Resistive Cooling of Trapped Highly-Charged Particles  

SciTech Connect

The increasing demand for high accuracies in atomic physics experiments requires intense beams of heavy and highly charged ions (HCI) which must be decelerated and cooled to extremely low energies. In the upcoming HITRAP (Highly charged Ion Trap) facility at GSI, Darmstadt HCI will be trapped and resistively cooled thanks to the electronic dissipation of kinetic energy on an external impedance. The cooling mechanism becomes highly nonlinear when applied to large ensembles of particles and due to the lack of thorough theoretical and experimental investigations the understanding of the process is still very limited. Our Particle-In-Cell simulations show the feasibility of this cooling mechanism and reveal some of its characteristic features.

Maero, G. [Gesellschaft fuer Schwerionenforschung mbH, Planckstrasse 1, 64291 Darmstadt (Germany); Dipartimento di Fisica, Universita degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Herfurth, F.; Kluge, H.-J.; Koszudowski, S.; Quint, W. [Gesellschaft fuer Schwerionenforschung mbH, Planckstrasse 1, 64291 Darmstadt (Germany); Kester, O.; Schwarz, S. [National Superconducting Cyclotron Laboratory, Michigan State University, 1 Cyclotron, East Lansing, MI 48824-1321 (United States)

2010-06-16

364

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

365

Trapping polar molecules in an ac trap  

SciTech Connect

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

Bethlem, Hendrick L. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); Laser Centre Vrije Universiteit, De Boelelaan 1081, NL-1081HV Amsterdam (Netherlands); Veldhoven, Jacqueline van [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); FOM-Institute for Plasmaphysics Rijnhuizen, P.O. Box 1207, NL-3430 BE Nieuwegein (Netherlands); Schnell, Melanie; Meijer, Gerard [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany)

2006-12-15

366

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

2011-06-28

367

Nutritive value of corn silage as affected by maturity and mechanical processing: a contemporary review.  

PubMed

Stage of maturity at harvest and mechanical processing affect the nutritive value of corn silage. The change in nutritive value of corn silage as maturity advances can be measured by animal digestion and macro in situ degradation studies among other methods. Predictive equations using climatic data, vitreousness of corn grain in corn silage, starch reactivity, gelatinization enthalpy, dry matter (DM) of corn grain in corn silage, and DM of corn silage can be used to estimate starch digestibility of corn silage. Whole plant corn silage can be mechanically processed either pre- or postensiling with a kernel processor mounted on a forage harvester, a recutter screen on a forage harvester, or a stationary roller mill. Mechanical processing of corn silage can improve ensiling characteristics, reduce DM losses during ensiling, and improve starch and fiber digestion as a result of fracturing the corn kernels and crushing and shearing the stover and cobs. Improvements in milk production have ranged from 0.2 to 2.0 kg/d when cows were fed mechanically processed corn silage. A consistent improvement in milk protein yield has also been observed when mechanically processed corn silage has been fed. With the advent of mechanical processors, alternative strategies are evident for corn silage management, such as a longer harvest window. PMID:10629831

Johnson, L; Harrison, J H; Hunt, C; Shinners, K; Doggett, C G; Sapienza, D

1999-12-01

368

Mechanics of a process to assemble microspheres on a patterned and Zhigang Suob  

E-print Network

Mechanics of a process to assemble microspheres on a patterned electrode Ting Zhua and Zhigang Suob April 2006 A process has been demonstrated recently to assemble microspheres on a patterned electrode both the conditions under which excess microspheres jump off the electrode when the voltage is applied

Prentiss, Mara

369

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

370

Post-processing of detailed chemical kinetic mechanisms onto CFD simulations  

Microsoft Academic Search

A new general method to combine computational fluid dynamics tools and detailed chemical kinetic mechanisms is presented. The method involves post-processing of data extracted from computational fluid dynamics (CFD) simulations obtained by using a simple reaction model to generate an overall estimate of the temperature and flow field in the computational domain. In post-processing of the data, the individual cells

M. S. Skjth-rasmussen; O. Holm-christensen; M. stberg; T. S. Christensen; T. Johannessen; A. D. Jensen; P. Glarborg; H. Livbjerg

2004-01-01

371

ON THE INFLUENCE OF HUMAN FACTOR ON MECHANICAL PROPERTIES IN ALUMINIUM HOT EXTRUSION PROCESS  

Microsoft Academic Search

A non-parametric model was proposed for modelling the influence of different technological and chemical pa- rameters on the mechanical properties of the 6082 aluminium alloys during the hot extrusion process with a special consideration of human factor. It was shown that human factor (influence of process engineers) was important and that it could be efficiently modelled and taken into account

I. PERU; M. FAZARINC; G. KUGLER; P. FAJFAR

372

Biodrying for mechanicalbiological treatment of wastes: A review of process science and engineering  

Microsoft Academic Search

Biodrying is a variation of aerobic decomposition, used within mechanicalbiological treatment (MBT) plants to dry and partially stabilise residual municipal waste. Biodrying MBT plants can produce a high quality solid recovered fuel (SRF), high in biomass content. Here, process objectives, operating principles, reactor designs, parameters for process monitoring and control, and their effect on biodried output quality are critically examined.

C. A. Velis; P. J. Longhurst; G. H. Drew; R. Smith; S. J. T. Pollard

2009-01-01

373

Traps for the Unwary Financial Aid Officer.  

ERIC Educational Resources Information Center

Describes 11 regulatory traps that can result in fraud and abuse charges. The traps are admissions process, ability to benefit, inability to document attendance, satisfactory academic progress, fictitious students, false eligibility, misstated needs, misuse of funds by students, theft and misuse of funds, lender kickbacks, and loan defaults.

Buchanan, E. T.

1986-01-01

374

An integrative process model of leadership: examining loci, mechanisms, and event cycles.  

PubMed

Utilizing the locus (source) and mechanism (transmission) of leadership framework (Hernandez, Eberly, Avolio, & Johnson, 2011), we propose and examine the application of an integrative process model of leadership to help determine the psychological interactive processes that constitute leadership. In particular, we identify the various dynamics involved in generating leadership processes by modeling how the loci and mechanisms interact through a series of leadership event cycles. We discuss the major implications of this model for advancing an integrative understanding of what constitutes leadership and its current and future impact on the field of psychological theory, research, and practice. PMID:23528243

Eberly, Marion B; Johnson, Michael D; Hernandez, Morela; Avolio, Bruce J

2013-09-01

375

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

376

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

377

Mechanisms of Thermochemical Biomass Conversion Processes. Part 3: Reactions of Liquefaction  

Microsoft Academic Search

This article reviews the liquefaction mechanisms of biomass structural constituents. One pivotal study of such liquefaction processes was done in the 1970s funded by the Bureau of Mines of the United States. Liquefaction is a low-temperature, high-pressure thermochemical process using a catalyst. The process produces a marketable liquid product. In the case of liquefaction, macromolecule compounds in biomass are degraded

M. Balat

2008-01-01

378

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

379

Mechanisms of food processing and storage-related stress tolerance in Clostridium botulinum.  

PubMed

Vegetative cultures of Clostridium botulinum produce the extremely potent botulinum neurotoxin, and may jeopardize the safety of foods unless sufficient measures to prevent growth are applied. Minimal food processing relies on combinations of mild treatments, primarily to avoid deterioration of the sensory qualities of the food. Tolerance of C. botulinum to minimal food processing is well characterized. However, data on effects of successive treatments on robustness towards further processing is lacking. Developments in genetic manipulation tools and the availability of annotated genomes have allowed identification of genetic mechanisms involved in stress tolerance of C. botulinum. Most studies focused on low temperature, and the importance of various regulatory mechanisms in cold tolerance of C. botulinum has been demonstrated. Furthermore, novel roles in cold tolerance were shown for metabolic pathways under the control of these regulators. A role for secondary oxidative stress in tolerance to extreme temperatures has been proposed. Additionally, genetic mechanisms related to tolerance to heat, low pH, and high salinity have been characterized. Data on genetic stress-related mechanisms of psychrotrophic Group II C. botulinum strains are scarce; these mechanisms are of interest for food safety research and should thus be investigated. This minireview encompasses the importance of C. botulinum as a food safety hazard and its central physiological characteristics related to food-processing and storage-related stress. Special attention is given to recent findings considering genetic mechanisms C. botulinum utilizes in detecting and countering these adverse conditions. PMID:25303833

Dahlsten, Elias; Lindstrm, Miia; Korkeala, Hannu

2014-10-01

380

Relationship between Microstructure, Material Distribution, and Mechanical Properties of Sheep Tibia during Fracture Healing Process  

PubMed Central

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

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

2013-01-01

381

A trapped ?eld of 17.6T in melt-processed, bulk Gd-Ba-Cu-O reinforced with shrink-?t steel  

E-print Network

than 77 K, and significantly larger mag- netic fields can be trapped. Notably, Tomita and Murakami reported a trapped field of 17.24 T at 29 K in an arrangement of two YBa2Cu3O7? ? (YBCO) samples of 26 mm diameter impregnated with Woods metal and resin... magnets operate in what is effectively persistent mode, which cannot yet be achieved in solenoids fabricated from YBCO-coated conductors due to the difficulty in making superconducting joints. There are significant challenges, beyond merely produ- cing a...

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.

2014-06-25

382

Observation of Cold Collisions between Trapped Ions and Trapped Atoms  

E-print Network

We study cold collisions between trapped ions and trapped atoms in the semiclassical (Langevin) regime. Using Yb(+) ions confined in a Paul trap and Yb atoms in a magneto-optical trap, we investigate charge-exchange ...

Orucevic, Fedja

383

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

384

HP Steam Trap Monitoring  

E-print Network

Steam Trap Monitoring ? Real-time monitoring for high-pressure critical traps (>15 PSIG) ? Average total system cost $25K - $50K ? Web-Based or Modbus/BMS Integration Basic Installation Wireless Signal Transmitter Receiver Repeater...

Pascone, S.

2011-01-01

385

Cognitive humor processing: different logical mechanisms in nonverbal cartoons--an fMRI study.  

PubMed

Although recent fMRI studies on humor have begun to elucidate cognitive and affective neural correlates, they weren't able to distinguish between different logical mechanisms or steps of humor processing, i.e., the detection of an incongruity and its resolution. This fMRI study aimed to focus in more detail on cognitive humor processing. In order to investigate pure incongruity resolution without preprocessing steps, nonverbal cartoons differing in their logical mechanisms were contrasted with nonhumorous pictures containing an irresolvable incongruity. The logical mechanisms were: (1) visual puns (visual resemblance, PUNs); (2) semantic cartoons (pure semantic relationships, SEMs); and (3) Theory of Mind cartoons (which require additionally mentalizing abilities, TOMs). Thirty cartoons from each condition were presented to 17 healthy subjects while acquiring fMR images. The results reveal a left-sided network involved in pure incongruity resolution: e.g., temporo-parietal junction, inferior frontal gyrus and ventromedian prefrontal cortex. These areas are also involved in processing of SEMs, whereas PUNs show more activation in the extrastriate cortex and TOMs show more activation in so-called mentalizing areas. Processing of pictures containing an irresolvable incongruity evokes activation in the rostral cingulate zone, which might reflect error processing. We conclude that cognitive processing of different logical mechanisms depends on separate neural networks. PMID:18633854

Samson, Andrea C; Zysset, Stefan; Huber, Oswald

2008-01-01

386

The effect of thermal processing on microstructure and mechanical properties in a nickel-iron alloy  

NASA Astrophysics Data System (ADS)

The correlation between processing conditions, resulted microstructure and mechanical properties is of interest in the field of metallurgy for centuries. In this work, we investigated the effect of thermal processing parameters on microstructure, and key mechanical properties to turbine rotor design: tensile yield strength and crack growth resistance, for a nickel-iron based superalloy Inconel 706. The first step of the designing of experiments is to find parameter ranges for thermal processing. Physical metallurgy on superalloys was combined with finite element analysis to estimate variations in thermal histories for a large Alloy 706 forging, and the results were adopted for designing of experiments. Through the systematic study, correlation was found between the processing parameters and the microstructure. Five different types of grain boundaries were identified by optical metallography, fractography, and transmission electron microscopy, and they were found to be associated with eta precipitation at the grain boundaries. Proportions of types of boundaries, eta size, spacing and angle respect to the grain boundary were found to be dependent on processing parameters. Differences in grain interior precipitates were also identified, and correlated with processing conditions. Further, a strong correlation between microstructure and mechanical properties was identified. The grain boundary precipitates affect the time dependent crack propagation resistance, and different types of boundaries have different levels of resistance. Grain interior precipitates were correlated with tensile yield strength. It was also found that there is a strong environmental effect on time dependent crack propagation resistance, and the sensitivity to environmental damage is microstructure dependent. The microstructure with eta decorated on grain boundaries by controlled processing parameters is more resistant to environmental damage through oxygen embrittlement than material without eta phase on grain boundaries. Effort was made to explore the mechanisms of improving the time dependent crack propagation resistance through thermal processing, several mechanisms were identified in both environment dependent and environment independent category, and they were ranked based on their contributions in affecting crack propagation.

Yang, Ling

387

Statistical and Experimental Analysis of Correlated Time-Varying Process Variables for Conditions Diagnosis in ChemicalMechanical Planarization  

Microsoft Academic Search

During chemical-mechanical planarization (CMP) of semiconductor wafers, chemical and mechanical process variables are strongly correlated and jointly affect polishing performance. The correlation among these process variables could potentially be utilized to characterize process conditions for the purpose of diagnosis. However, process variables measured during CMP, such as the temperature distribution and coefficient of friction between wafer and pad, vary with

Xi Zhang; Hui Wang; Qiang Huang; Ashok Kumar; Jingmei Zhai

2009-01-01

388

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.

Lawrence Hall of Science

1979-01-01

389

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

390

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

PubMed Central

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

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

2013-01-01

391

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

PubMed

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

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

2013-03-01

392

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

393

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...

394

Electrical conduction and trapping distributions in tellurium oxide films  

Microsoft Academic Search

The electrical charge transport and trapping distribution was studied in vacuum-deposited tellurium oxide films. The current-voltage characteristics suggested a space-charge-limited conduction process at higher voltage levels. Assuming an exponential type of trapping distribution the density of traps estimated from (log10J)-(1\\/T) curves were (0.5-6.0)1024 m-3.

Amarjit Singh

1988-01-01

395

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

PubMed Central

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

2014-01-01

396

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 108:1141711422], 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

397

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.

398

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

399

Trap-induced photoconductivity in singlet fission pentacene diodes  

SciTech Connect

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, E-mail: qiaoxianfeng@hotmail.com; Zhao, Chen; Chen, Bingbing; Luan, Lin [WuHan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wu Han 430074 (China)

2014-07-21

400

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

SciTech Connect

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 [Laboratoire Materiaux, ECAM, 40 montee Saint Barthelemy, 69321, Lyon, Cedex 05 (France); Arts et Metiers ParisTech, MecaSurf Laboratory (EA 4496), 2, Cours des Arts et Metiers, 13617 Aix en Provence (France); Jaccquet, Philippe; Moinard-Checot, Delphine [Laboratoire Materiaux, ECAM, 40 montee Saint Barthelemy, 69321, Lyon, Cedex 05 (France); Arts et Metiers ParisTech, LaBoMaP, Rue Porte de Paris, 71250 CLUNY (France); Fabre, Agnes; Barrallier, Laurent [Arts et Metiers ParisTech, MecaSurf Laboratory (EA 4496), 2, Cours des Arts et Metiers, 13617 Aix en Provence (France)

2011-01-17

401

Superconducting microfabricated ion traps  

E-print Network

We fabricate superconducting ion traps with niobium and niobium nitride and trap single 88Sr ions at cryogenic temperatures. The superconducting transition is verified and characterized by measuring the resistance and critical current using a 4-wire measurement on the trap structure, and observing change in the rf reflection. The lowest observed heating rate is 2.1(3) quanta/sec at 800 kHz at 6 K and shows no significant change across the superconducting transition, suggesting that anomalous heating is primarily caused by noise sources on the surface. This demonstration of superconducting ion traps opens up possibilities for integrating trapped ions and molecular ions with superconducting devices.

Shannon X. Wang; Yufei Ge; Jaroslaw Labaziewicz; Eric Dauler; Karl Berggren; Isaac L. Chuang

2010-12-14

402

Trapping effects in irradiated and avalanche-injected MOS capacitors  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

403

Structures and magnetic properties of ironnitrogen alloy powders prepared by mechanical alloying process  

Microsoft Academic Search

An investigation of forming ironnitrogen solid solution was made by applying a mechanical alloying process to the mixture of Fe and Fe4N powders. Following the collapse of the FCC structure of Fe4N at an early stage of milling process, a single phased structure which could be regarded as BCC-like FeN solid solution was formed. A certain amount of increase in

Toshinao Yamaguchi; Hisakazu Saihata

2003-01-01

404

Coupled thermo-mechanical finite-element modelling of hot ring rolling process  

Microsoft Academic Search

A general purpose, proprietary finite-element software program, Marc\\/Mentat, has been used to develop a coupled thermo-mechanical model of the deformation processes occurring during the hot rolling of IN718 rings. Unique features of the model are: (1) it adopts a transient or unsteady state full ring mesh to model the deformation process and shape development; (2) the mandrel and drive rolls

J. L. Song; A. L. Dowson; M. H. Jacobs; J. Brooks; I. Beden

2002-01-01

405

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

SciTech Connect

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

Flores-Campos, R., E-mail: ruben.flores@itesm.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No. 120, CP 31109, Chihuahua, Chih., Mexico (Mexico); Tecnologico de Monterrey Campus Saltillo, Departamento de Ingenieria, Prol. Juan de la Barrera No. 1241 Ote., Col. Cumbres, CP 25270, Saltillo, Coah., Mexico (Mexico); Estrada-Guel, I., E-mail: ivanovich.estrada@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No. 120, CP 31109, Chihuahua, Chih., Mexico (Mexico); Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No. 120, CP 31109, Chihuahua, Chih., Mexico (Mexico); Martinez-Sanchez, R., E-mail: roberto.martinez@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No. 120, CP 31109, Chihuahua, Chih., Mexico (Mexico); Herrera-Ramirez, J.M., E-mail: martin.herrera@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No. 120, CP 31109, Chihuahua, Chih., Mexico (Mexico)

2012-01-15

406

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

407

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

SciTech Connect

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.

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

2010-06-15

408

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

Edinliler, Ay?e; Baykal, Gkhan; Saygili, Altug

2010-06-01

409

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

SciTech Connect

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

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

2012-01-15

410

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

411

Mechanisms of Thermochemical Biomass Conversion Processes. Part 1: Reactions of Pyrolysis  

Microsoft Academic Search

The present work is a study on the pyrolysis mechanisms of biomass structural constituents. Biomass resources include wood and wood wastes, agricultural crops and their waste byproducts, municipal solid waste, animal wastes, waste from food processing, and aquatic plants and algae. The major organic components of biomass can be classified as cellulose, hemicelluloses, and lignin. The pyrolysis is thermal degradation

M. Balat

2008-01-01

412

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-structured vanadium (V), a bcc metal with a moderately high melting temperature (1910 °C) by high-energy ball milling. Published by Elsevier Ltd. All rights reserved. Keywords: Nano-structured metals; bcc structure; Vanadium

Wei, Qiuming

413

Modifications of mechanical and electrochemical properties of stainless steel surfaces by laser shock processing  

Microsoft Academic Search

Laser Shock Processing (LSP) consists on focusing a high energy pulsed laser beam on metals to create shock waves and thereby, generate compressive stresses. These stress are similar to those of conventional mechanical treatments like short peening. Nevertheless, at LSP the affected depths are greater and the surfaces keep their roughness and hardness. The present study compare the effects of

X. Scherpereel; Patrice Peyre; Remy Fabbro; G. Lederer; N. Celati

1997-01-01

414

Carbon nanotubes based ultrasonic transducer: realization process, morphological and mechanical properties  

E-print Network

Carbon nanotubes based ultrasonic transducer: realization process, morphological and mechanical in cementitous materials, carbon nanotubes based capacitive ultrasonic transducers (cMUT) are promising sensors (1 µm²). In the proposed device, the cMUT membrane is made of aligned single-walled carbon nanotubes

Paris-Sud XI, Université de

415

Thermo-Mechanical Model of Solidification Processes with Seid Koric and Brian G. Thomas  

E-print Network

implemented into Abaqus, (Abaqus Inc., 2005) using a user-defined subroutine (UMAT) to integrateThermo-Mechanical Model of Solidification Processes with Abaqus Seid Koric and Brian G. Thomas Casting, Finite Elements, Abaqus, UMAT, CON2D, Fixed Grid, Solidification, Thin Slab Casting, Funnel Mold

Thomas, Brian G.

416

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

417

66 )6/-786 The Mechanism of Speech Processing in Congenital  

E-print Network

;The Mechanism of Speech Processing in Congenital Amusia: Evidence from Mandarin Speakers Fang Liu1 of Mandarin speakers with congenital amusia. Thirteen Mandarin amusics and thirteen matched controls sample of Mandarin amusics and on amusics of other language backgrounds are needed to consolidate

Miranda, Eduardo Reck

418

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

419

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

E-print Network

and produce novel polymer systems through complex physico-chemical means. High-energy ball milling, originallyOn the similarity of macromolecular responses to high-energy processes: mechanical milling vs and Engineering, North Carolina State University, Raleigh NC 27695, USA b Department of Chemical Engineering

420

Wireless sensor fusion approach for monitoring chemical mechanical planarization (CMP) process  

Microsoft Academic Search

Chemical mechanical planarization (CMP) is used in the microelectronics and optical industries for local as well as global planarity and for producing mirror finished surfaces. Roughness (Ra), within-non-uniformity (WIWNU), and material removal rate (MRR) are the major performance variables in polishing. CMP is a complex process involving some 36 input variables. Analysis of the review of the literatures showed that

Amit Ohri

2010-01-01

421

Tribological, thermal and kinetic characterization of dielectric and metal chemical mechanical planarization processes  

Microsoft Academic Search

This dissertation presents a series of studies that describe the impacts of, among other things, temperature and kinematics on inter-level dielectric (ILD) and metal chemical mechanical planarization (CMP) processes. The performance of CMP is often evaluated in terms of removal rate, uniformity, planarization length, step height, defects and resulting topography such as erosion and dishing. The assessment of these parameters

Jamshid Sorooshian

2005-01-01

422

Combustion synthesis/quasi-isostatic pressing of TiCNiTi cermets: processing and mechanical response  

E-print Network

Combustion synthesis/quasi-isostatic pressing of TiC­NiTi cermets: processing and mechanical and alumina particulate before initiation of the combustion reaction. The sample was ignited within the particulate and subjected to a uniaxial load immediately after passage of the combustion wave

Meyers, Marc A.

423

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

424

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

425

Inexpensive, floating, insect-emergence trap  

SciTech Connect

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

Cushman, R.M.

1983-11-01

426

Micro-fabricated stylus ion trap  

NASA Astrophysics Data System (ADS)

An electroformed, three-dimensional stylus Paul trap was designed to confine a single atomic ion for use as a sensor to probe the electric-field noise of proximate surfaces. The trap was microfabricated with the UV-LIGA technique to reduce the distance of the ion from the surface of interest. We detail the fabrication process used to produce a 150 ?m tall stylus trap with feature sizes of 40 ?m. We confined single, laser-cooled, 25Mg+ ions with lifetimes greater than 2 h above the stylus trap in an ultra-high-vacuum environment. After cooling a motional mode of the ion at 4 MHz close to its ground state (?n? = 0.34 0.07), the heating rate of the trap was measured with Raman sideband spectroscopy to be 387 15 quanta/s at an ion height of 62 ?m above the stylus electrodes.

Arrington, Christian L.; McKay, Kyle S.; Baca, Ehren D.; Coleman, Jonathan J.; Colombe, Yves; Finnegan, Patrick; Hite, Dustin A.; Hollowell, Andrew E.; Jrdens, Robert; Jost, John D.; Leibfried, Dietrich; Rowen, Adam M.; Warring, Ulrich; Weides, Martin; Wilson, Andrew C.; Wineland, David J.; Pappas, David P.

2013-08-01

427

A process for the agile product realization of electro-mechanical devices  

SciTech Connect

This paper describes a product realization process developed and demonstrated at Sandia by the A-PRIMED (Agile Product Realization for Innovative Electro MEchanical Devices) project that integrates many of the key components of ``agile manufacturing`` into a complete, design-to-production process. Evidence indicates that the process has reduced the product realization cycle and assured product quality. Products included discriminators for a robotic quick change adapter and for an electronic defense system. These discriminators, built using A-PRIMED, met random vibration requirements and had life cycles that far surpass the performance obtained from earlier efforts.

Forsythe, C.; Ashby, M.R.; Benavides, G.L.; Diegert, K.V.; Jones, R.E.; Longcope, D.B.; Parratt, S.W.

1995-09-01

428

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

429

Trap-induced losses in hybrid photovoltaics.  

PubMed

We investigate the loss mechanisms in hybrid photovoltaics based on blends of poly(3-hexylthiophene) with CdSe nanocrystals of various sizes. By combining the spectroscopic and electrical measurements on working devices as well as films, we identify that high trap-mediated recombination is responsible for the loss of photogenerated charge carriers in devices with small nanocrystals. In addition, we demonstrate that the reduced open-circuit voltage for devices with small nanocrystals is also caused by the traps. PMID:24606110

Gao, Feng; Li, Zhe; Wang, Jianpu; Rao, Akshay; Howard, Ian A; Abrusci, Agnese; Massip, Sylvain; McNeill, Christopher R; Greenham, Neil C

2014-04-22

430

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, 55235527 (1977). We explain the relaxation process in charge trapping events by introducing a nonlinear charge trapping model. This model provides a description on the manner in which the transport of mobile defects affects the long-tail current relaxation processes in low-k films.

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

431

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.; Offenhusser, A.; Vitusevich, S. A., E-mail: s.vitusevich@fz-juelich.de [Peter Grnberg Institute (PGI-8), Forschungszentrum Jlich, 52425 Jlich (Germany); Gasparyan, F. [Peter Grnberg Institute (PGI-8), Forschungszentrum Jlich, 52425 Jlich (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

432

Trapping of Radioactive Atoms: the Legnaro Francium Magneto-Optical Trap  

Microsoft Academic Search

Experiments aimed at laser cooling and trapping of radioactive atoms are nowadays operational at several laboratories. They open up a bridge between atomic and nuclear physics, allowing new precise spectroscopic measurements and detailed analysis of nuclear decay processes. A magneto-optical trap (MOT) for francium atoms is almost operational at the INFN Legnaro laboratories; its characterization and optimization are under way.

S. N. Atutov; V. Biancalana; A. Burchianti; R. Calabrese; L. Corradi; A. Dainelli; V. Guidi; B. Mali; C. Marinelli; E. Mariotti; L. Moi; E. Scansani; G. Stancari; L. Tomassetti; S. Veronesi

2003-01-01

433

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

434

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

435

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

436

Improvement of Structural and Mechanical Properties of Al-1100 Alloy via Friction Stir Processing  

NASA Astrophysics Data System (ADS)

In the present study, the relationship between structural and mechanical properties of friction stir processed Al-1100 alloy and process parameters (tool rotation rate: ? and traverse speed: ?) was studied to get an better understanding and optimizing the friction stir processing (FSP) condition of this alloy. Microstructural studies revealed that increasing of ? up to 720 rpm resulted in grain refinement in the stirred zone (SZ), but higher increasing of ? caused grain growth in this zone. These variations of SZ grain size illustrated that the prevailing factor that determined the SZ grain size was plastic deformation at first and thereafter, peak temperature in the SZ. Mechanical properties investigations were in accordance with microstructural findings and illustrated that optimized FSP condition for Al-1100 alloy was 720 rpm and 20 mm/min. Optimized FSP condition resulted in a significant improvement of tensile strength and elongation up to 22 and 8% of those of base metal, respectively.

Mosallaee, M.; Dehghan, M.

2014-10-01

437

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 m) 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.

2014-09-01

438

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 m) 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

439

Attentional and emotional mechanisms of pain processing and their related factors: A structural equations approach  

PubMed Central

BACKGROUND/OBJECTIVE: It is known that maladaptive attentional and emotional mechanisms of pain processing as indicated by constructs such as pain hypervigilance, pain-related anxiety and pain catastrophizing play an important role in the development and maintenance of chronic pain conditions. However, little is known to date about the potential risk factors for these forms of maladaptive processing. The aim of the present study was to shed more light on this issue. A very comprehensive set of predictor variables was examined in healthy pain-free subjects. METHOD: Participants were 92 young and healthy subjects (mean [ SD] age 26.996.90 years; 47 men, 45 women). Maladaptive attentional and emotional mechanisms of pain processing were assessed by self-report measures of pain hypervigilance, pain-related anxiety and pain catastrophizing, as well as by a dot-probe task. The comprehensive set of predictor variables included measures of affective and bodily distress (depression, anxiety and somatization), experimental pain sensitivity, and cortisol reactivity. Directed relationships were estimated by using structural equation modelling. RESULTS: Structural equation modelling revealed a significant path from affective and bodily distress to self-reported maladaptive attentional and emotional pain processing. In contrast, the paths from pain sensitivity and cortisol reactivity did not reach the level of significance. CONCLUSION: These results support the position that anxiety and depression, as well as somatization, contribute to the aberrance of attentional and emotional mechanisms of pain processing. Surprisingly, the assumption of a close relationship between these maladaptive mechanisms of pain processing and pain sensitivity could not be confirmed. PMID:20808968

Huber, Claudia; Kunz, Miriam; Artelt, Cordula; Lautenbacher, Stefan

2010-01-01

440

Feedback cooling of a single trapped ion  

E-print Network

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

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

2005-09-19

441

Laser trapping of {sup 21}Na atoms  

SciTech Connect

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

Lu, Zheng-Tian

1994-09-01

442

Interaction of thermal and mechanical processes in steep permafrost rock walls: A conceptual approach  

NASA Astrophysics Data System (ADS)

Degradation of permafrost rock wall decreases stability and can initiate rock slope instability of all magnitudes. Rock instability is controlled by the balance of shear forces and shear resistances. The sensitivity of slope stability to warming results from a complex interplay of shear forces and resistances. Conductive, convective and advective heat transport processes act to warm, degrade and thaw permafrost in rock walls. On a seasonal scale, snow cover changes are a poorly understood key control of the timing and extent of thawing and permafrost degradation. We identified two potential critical time windows where shear forces might exceed shear resistances of the rock. In early summer combined hydrostatic and cryostatic pressure can cause a peak in shear force exceeding high frozen shear resistance and in autumn fast increasing shear forces can exceed slower increasing shear resistance. On a multiannual system scale, shear resistances change from predominantly rock-mechanically to ice-mechanically controlled. Progressive rock bridge failure results in an increase of sensitivity to warming. Climate change alters snow cover and duration and, hereby, thermal and mechanical processes in the rock wall. Amplified thawing of permafrost will result in higher rock slope instability and rock fall activity. We present a holistic conceptual approach connecting thermal and mechanical processes, validate parts of the model with geophysical and kinematic data and develop future scenarios to enhance understanding on system scale.

Draebing, D.; Krautblatter, M.; Dikau, R.

2014-12-01

443

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

NASA Astrophysics Data System (ADS)

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

Ducato, Antonino; Fratini, Livan; Micari, Fabrizio

2013-05-01

444

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

445

Microfabricated ion trap array  

DOEpatents

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

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

2006-12-26

446

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

447

Processing of a Ni-35at% Al alloy by mechanically milling and consolidation  

SciTech Connect

The effect of processing and heat treatment conditions on the microstructure and mechanical behavior of a Ni-35at% Al shape memory alloy has been investigated. Compacts have been produced from as-received (prealloyed) powder and the powder obtained after ball or attritor milling of the prealloyed powder. These compacts have been compared with each other and with conventionally cast material in terms of microstructure, phase transformations and behavior in compression. The results indicate that milled powders, which are nanocrystalline, show better sinterability, mechanical properties and a reversible martensitic transformation that is essential for the shape memory effect.

Wolska, J.A.; Monster, G.B. [Univ. of Twente, Enschede (Netherlands); Chandrasekaran, M. [A.M.T.n.v., Herk-de-Stad (Belgium)

1995-12-31

448

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

NASA Technical Reports Server (NTRS)

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

Oravec, Heather Ann; Daniels, Christopher C.

2014-01-01

449

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

NASA Astrophysics Data System (ADS)

Cold spray is a coating technology based on aerodynamics and high-speed impact dynamics. In this process, spray particles (usually 1-50 ?m in diameter) are accelerated to a high velocity (typically 300-1200 m/s) by a high-speed gas (pre-heated air, nitrogen, or helium) flow that is generated through a convergent-divergent