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1

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

SciTech Connect

The ultimate fate of CO{sub 2} injected into saline aquifers for environmental isolation is governed by three interdependent yet conceptually distinct processes: CO{sub 2} 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 to a corresponding trapping mechanism: immiscible plume migration to hydrodynamic trapping, plume-water interaction to solubility trapping, and plume-mineral interaction to mineral trapping. In this study, reactive transport modeling of CO{sub 2} storage in a shale-capped sandstone aquifer at Sleipner has elucidated and established key parametric dependencies of these fundamental processes, the associated trapping mechanisms, and sequestration partitioning among them during consecutive 10-year prograde (active-injection) and retrograde (post-injection) regimes. Intra-aquifer permeability structure controls the path of immiscible CO{sub 2} migration, thereby establishing the spatial framework of plume-aquifer interaction and the potential effectiveness of solubility and mineral trapping. Inter-bedded thin shales--which occur at Sleipner--retard vertical and promote lateral plume migration, thereby significantly expanding this framework and enhancing this potential. Actual efficacy of these trapping mechanisms is determined by compositional characteristics of the aquifer and cap rock: the degree of solubility trapping decreases with increasing formation-water salinity, while that of mineral trapping is proportional to the bulk concentration of carbonate-forming elements--principally Fe, Mg, Ca, Na, and Al. In the near-field environment of Sleipner-like settings, 80-85% by mass of injected CO{sub 2} remains and migrates as an immiscible fluid phase, 15-20% dissolves into formation waters, and less than 1% precipitates as carbonate minerals. This partitioning defines the relative effectiveness of hydrodynamic, solubility, and mineral trapping on a mass basis. Seemingly inconsequential, mineral trapping has enormous strategic significance: it maintains injectivity, delineates the storage volume, and improves cap-rock integrity. We have identified four distinct mechanisms: dawsonite [NaAlCO{sub 3}(OH){sub 2}] cementation occurs throughout the intra-aquifer plume, while calcite-group carbonates [principally, (Fe,Mg,Ca)CO{sub 3}] precipitate via disparate processes along lateral and upper plume margins, and by yet another process within inter-bedded and cap-rock shales. The coupled mineral dissolution/precipitation reaction associated with each mechanism reduces local porosity and permeability. For Sleipner-like settings, the magnitude of such reduction for dawsonite cementation is near negligible; hence, this process effectively maintains initial CO{sub 2} injectivity. Of similarly small magnitude is the reduction associated with formation of carbonate rind along upper and lateral plume boundaries; these processes effectively delineate the CO{sub 2} storage volume, and for saline aquifers anomalously rich in Fe-Mg-Ca may partially self-seal the plume. Porosity and permeability reduction is most extreme within shales, because their clay-rich mineralogy defines bulk Fe-Mg concentrations much greater than those of saline aquifers. In the basal cap-rock shale of our models, these reductions amount to 4.5 and 13%, respectively, after the prograde regime. During the retrograde phase, residual saturation of immiscible CO{sub 2} maintains the prograde extent of solubility trapping while continuously enhancing that of mineral trapping. At the close of our 20-year simulations, initial porosity and permeability of the basal cap-rock shale have been reduced by 8 and 22%, respectively. Extrapolating to hypothetical complete consumption of Fe-Mg-bearing shale minerals (here, 10 vol.% Mg-chlorite) yields an ultimate reduction of about 52 and 90%, respectively, after 130 years. Hence, the most crucial strategic impa

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

2004-07-26

2

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

3

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

4

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

5

Microfabrication techniques for trapped ion quantum information processing  

NASA Astrophysics Data System (ADS)

Quantum-mechanical principles can be used to process information. In one approach, linear arrays of trapped, laser cooled ion qubits (two-level quantum systems) are confined in segmented multi-zone electrode structures. Strong Coulomb coupling between ions is the basis for quantum gates mediated by phonon exchange. Applications of Quantum Information Processing (QIP) include solution of problems believed to be intractable on classical computers. The ion trap approach to QIP requires trapping and control of numerous ions in electrode structures with many trapping zones. In support of trapped ion QIP, I investigated microfabrication of structures to trap, transport and couple large numbers of ions. Using 24Mg + I demonstrated loading and transport between zones in microtraps made of boron doped silicon. This thesis describes the fundamentals of ion trapping, the characteristics of silicon-based traps amenable to QIP work and apparatus to trap ions and characterize traps. Microfabrication instructions appropriate for nonexperts are included. A key characteristic of ion traps is the rate at which ion motional modes heat. In my traps upper bounds on heating were determined; however, heating due to externally injected noise could not be completely ruled out. Noise on the RF potential responsible for providing confinement was identified as one source of injected noise. Using the microfabrication technology developed for ion traps, I made a cantilevered micromechanical oscillator and with coworkers demonstrated a method to reduce the kinetic energy of its lowest order mechanical mode via its capacitive coupling to a driven RF resonant circuit. Cooling results from a RF capacitive force, which is phase shifted relative to the cantilever motion. The technique was demonstrated by cooling a 7 kHz fundamental mode from room temperature to 45 K. Ground state cooling of the mechanical modes of motion of harmonically trapped ions is routine; equivalent cooling of a macroscopic harmonic oscillator has not yet been demonstrated. Extension of this method to devices with higher motional frequencies in a cryogenic system, could enable ground state cooling and may prove simpler than related optical experiments. I also discuss an implementation of the semiclassical quantum Fourier transform (QFT) using three beryllium ion qubits. The QFT is a crucial step in a number of quantum algorithms including Shor's algorithm, a quantum approach to integer factorization which is exponentially faster than the fastest known classical factoring algorithm. This demonstration incorporated the key elements of a scalable ion-trap architecture for QIP.

Britton, Joe

6

CO2 Capillary-Trapping Processes in Deep Saline Aquifers  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

7

Hydrogen-Trapping Mechanisms in Nanostructured Steels  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

8

Influence of small scale heterogeneity on CO2 trapping processes in deep saline aquifers  

E-print Network

The physical mechanism of CO2 trapping in porous media by capillary trapping (pore scale) incorporates a number of related processes, i.e. residual trapping, trapping due to hysteresis of the relative permeability, and trapping due to hysteresis of the capillary pressure. Additionally CO2 may be trapped in heterogeneous media due to difference in capillary pressure entry points for different materials (facies scale). The amount of CO2 trapped by these processes depends upon a complex system of non-linear and hysteretic relationships including how relative permeability and capillary pressure vary with brine and CO2 saturation, and upon the spatial variation in these relationships as caused by geologic heterogeneity. Geological heterogeneities affect the dynamics of CO2 plumes in subsurface environments. Recent studies have led to new conceptual and quantitative models for sedimentary architecture in fluvial deposits over a range of scales that are relevant to the performance of some deep saline reservoirs. We ...

Gershenzon, Naum I; Ritzi, Robert W; Dominic, David F

2014-01-01

9

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

SciTech Connect

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

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

1983-02-01

10

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

11

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

12

Quantum information processing with trapped electrons and superconducting electronics  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

13

Trapped Atomic Ions and Quantum Information Processing  

Microsoft Academic Search

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

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

2006-01-01

14

Materials processing routes to trap-free halide perovskites.  

PubMed

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

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

2014-11-12

15

Optimization geological sequestration of CO2 by capillary trapping mechanisms  

NASA Astrophysics Data System (ADS)

Geological carbon sequestration, as a method of atmospheric greenhouse gas reduction, is at the technological forefront of the climate change movement. Sequestration is achieved by capturing carbon dioxide (CO2) gas effluent from coal fired power plants and injecting it into saline aquifers. In an effort to fully understand and optimize CO2 trapping efficiency, the capillary trapping mechanisms that immobilize subsurface CO2 were analyzed at the pore scale. Pairs of analogous fluids representing the range of in situ supercritical CO2 and brine conditions were used during experimentation. The two fluids (identified as wetting and non wetting) were imbibed and drained from a flow cell apparatus containing a sintered glass bead column. Experimental and fluid parameters, such as interfacial tension, non-wetting fluid viscosity, and flow rate, were altered to characterize their impact on capillary trapping. Through the use of computed x-ray microtomography (CMT), we were able to quantify distinct differences between initial (post NW phase imbibition) and residual (post wetting fluid flood) non-wetting phase saturations. Alterations to the viscosity of the non-wetting and wetting fluid phases were made during experimentation; results indicate that the viscosity of the non-wetting fluid is the parameter of interest as residual saturations increased with increasing viscosity. These observed trends will be used to identify optimal conditions for trapping CO2 during subsurface sequestration.

Wildenschild, D.; Harper, E.; Herring, A. L.; Armstrong, R. T.

2012-12-01

16

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.

17

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

18

Theory and Simulation of Neoclassical Transport Processes, with Local Trapping  

E-print Network

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

California at San Diego, University of

19

Post Processing Strategies in EPR Spin-Trapping Studies  

Microsoft Academic Search

Collection of EPR spectra in digital format permits post processing that can be more meaningful than multiple-scan averaging, especially for spectra that are overlapping and changing with time, as is characteristic of spectra acquired in spin-trapping studies. It is demonstrated that multiple linear regression analysis of multiple spectra acquired in time-sequence can provide kinetic information even when the signal-to-noise of

Agnes Keszler; Neil Hogg

20

Absorption spectroscopy of single red blood cells in the presence of mechanical deformations induced by optical traps  

NASA Astrophysics Data System (ADS)

The electronic properties of single human red blood cells under mechanical deformations were investigated using a combination of dual beam optical tweezers and UV-vis absorption spectroscopy. The mechanical deformations were induced by two near-infrared optical traps with different trapping powers and trap configurations. The deformations were applied in two ways: locally, due to the mechanical forces around the traps, and by stretching the cell by moving the traps in opposite directions. In the presence of local deformations, the single cell undergoes a transition from an oxygenated state to a partially deoxygenated state. This process was found to be reversible and strongly power-dependent. Stretching the cell caused an opposite effect, indicating that the electronic response of the whole cell is dominated by the local interaction with the trapping beams. Results are discussed considering light-induced local heating, the Stark effect, and biochemical alterations due to mechanical forces, and are compared with reports of previous Raman spectroscopy studies. The information gained by the analysis of a single red blood cell's electronic response facilitates the understanding of fundamental physiological processes and sheds further light on the cell's mechanochemistry. This information may offer new opportunities for the diagnosis and treatment of blood diseases.

Wojdyla, Michal; Raj, Saurabh; Petrov, Dmitri

2012-09-01

21

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

22

A family of synthetic riboswitches adopts a kinetic trapping mechanism.  

PubMed

Riboswitches are sequences of RNA that control gene expression via RNA-ligand 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 (? 10(13) 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

23

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

24

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

PubMed Central

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

Vincent, Olivier; Roditchev, Ivan; Marmottant, Philippe

2011-01-01

25

Spontaneous firings of carnivorous aquatic Utricularia traps: temporal patterns and mechanical oscillations.  

PubMed

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

Vincent, Olivier; Roditchev, Ivan; Marmottant, Philippe

2011-01-01

26

Escape mechanism of a self-trapped topological soliton Yongwoo Shin, Minghai Li, Andr L. Botelho, and Xi Lin*  

E-print Network

Escape mechanism of a self-trapped topological soliton Yongwoo Shin, Minghai Li, André L. Botelho a universal escape mechanism for the self-trapped domain walls. They escape by continuously adjusting

Lin, Xi

27

Mechanism for hot-carrier-induced interface trap generation in MOS transistors  

Microsoft Academic Search

New experiments for the deuterium isotope effect for hot hole and electron injection have been performed to probe the mechanism for the interface trap generation in n-MOS transistors. The results from these new experiments suggest that electrons in the channel, but not those electrons or holes injected into the oxide, are primarily responsible for the interface trap generation. The bond

Zhi Cheda; K. Hess; Jinju Lee; Joseph W. Lyding; E. Rosenbaum; I. Kizilyalli; S. Chetlur

1999-01-01

28

On the mechanism for interface trap generation in MOS transistors due to channel hot carrier stressing  

Microsoft Academic Search

The classical concept and theory suggest that the degradation of MOS transistors is caused by interface trap generation resulting from hot carrier injection. We report three new experiments that use the deuterium isotope effect to probe the mechanism for interface trap generation in n-MOS transistors in the presence of hot hole and electron injection. These experiments show clearly that hot

Zhi Chen; Karl Hess; Jinju Lee; Joseph W. Lyding; Elyze Rosenbaum; Isik Kizilyalli; Sundar Chetlur; Robert Huang

2000-01-01

29

The impact of local-scale processes on solubility and capillary trapping of injected CO2  

NASA Astrophysics Data System (ADS)

Storage security of injected carbon dioxide (CO2) is an essential component of risk management for geological carbon sequestration operations. In the post-injection phase, the mobile CO2 plume migrates in large part due to buoyancy forces, following the natural topography of the geological formation, and may travel over very large distances before eventually being trapped by different physical and chemical processes. The primary trapping mechanisms are capillary and solubility trapping, which evolve over hundreds to thousands of years and can immobilize a significant portion of the mobile, free-phase CO2 plume. However, both the migration and trapping processes are inherently complex, involving a combination of small and large spatial scales and acting over a range of time scales. Solubility trapping is a good example of this complexity, where small-scale density instabilities in the dissolved CO2 region leads to convective mixing that has that has a significant effect on the large-scale dissolution process over very long time scales. Another example is the effect of capillary forces on the evolution of mobile CO2, where local capillary effects acting at the CO2-brine interface lead to a transition zone that may have a significant impact on large-scale plume migration dynamics. Appropriate modeling tools need to be developed that can capture both large and small-scale trapping effects in a practical way. We present a modeling approach that combines vertically-averaged governing equations with upscaled representations of the dissolution-convective mixing process and the local capillary transition zone or fringe. In this model, large-scale CO2 migration is captured numerically, while the small-scale dissolution-convection and capillary fringe effects are included using sub-grid corrections. In this way, we can eliminate the need for expensive grid refinement to capture the subscale instabilities associated with convective mixing or the details of the capillary transition zone. With this modeling approach, we examine the effect of different modeling choices associated with dissolution and capillary processes for typical large-scale systems that are naturally heterogeneous and geologically complex. We demonstrate that practical models such as this are essential for understanding the role of these processes on the long-term storage security of CO2 sequestration operations.

Gasda, S. E.; Nordbotten, J. M.; Celia, M. A.

2010-12-01

30

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; Ahren, Dag

2013-01-01

31

Optoelectronic neural dendritic tree processing with electron-trapping materials  

NASA Astrophysics Data System (ADS)

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

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

1995-03-01

32

Arbitrary waveform generator for quantum information processing with trapped ions  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

33

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

PubMed

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

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

2014-10-15

34

Evaluation of the Forrester-Hepburn Mechanism as an Artifact Source in ESR Spin-Trapping  

PubMed Central

Nitrone spin traps such as 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) are commonly used for free radical detection. Though proven examples are rare, artifact formation must be considered. For example, the Forrester-Hepburn mechanism yields the same radical adduct as formed by genuine radical trapping. A hydroxylamine is formed by nucleophilic attack of the substrate to DMPO and subsequently oxidized to the respective nitroxide radical. One potential candidate for this artifact is the sulfur trioxide radical adduct (DMPO/SO3?), as detected in spin-trapping experiments with horseradish peroxidase and sulfite. It has previously been shown by NMR experiments that the hydroxylamine intermediate does indeed form, but no direct proof for the ESR artifact has been provided. Here we used isotopically labeled DMPO with horseradish peroxidase and ferricyanide to test for the Forrester-Hepburn artifact directly in a spin-trapping experiment. Besides sulfite, we investigated other nucleophiles such as cyanide, cysteine and glutathione. Neither sulfite nor biological thiols produced detectable spin-trapping artifacts, but with cyanide the relatively weak signal originated almost entirely from the nucleophilic reaction. The hydroxylamine intermediate, which is more abundant with cyanide than with sulfite, was identified as cyano-hydroxylamine by means of 2D NMR experiments. Although our study found that spin trapping provided authentic free radical signals with most of the substrates, the occurrence of the Forrester Hepburn mechanism artifact with cyanide emphasizes the importance of isotope measurements with nucleophile substrates. PMID:22004308

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

2012-01-01

35

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

36

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...

37

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

PubMed

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

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

2013-12-01

38

On an excitation mechanism for trapped inertial waves in discs around black holes  

E-print Network

According to one model, high-frequency quasi-periodic oscillations (QPOs) can be identified with inertial waves, trapped in the inner regions of accretion discs around black holes due to relativistic effects. In order to be detected, their amplitudes need to reach large enough values via some excitation mechanism. We work out in detail a non-linear coupling mechanism suggested by Kato, in which a global warping or eccentricity of the disc has a fundamental role. These large-scale deformations combine with trapped modes to generate `intermediate' waves of negative energy that are damped as they approach either their corotation resonance or the inner edge of the disc, resulting in amplification of the trapped waves. We determine the growth rates of the inertial modes, as well as their dependence on the spin of the black hole and the properties of the disc. Our results indicate that this coupling mechanism can provide an efficient excitation of trapped inertial waves, provided the global deformations reach the inner part of the disc with non-negligible amplitude.

Barbara T. Ferreira; Gordon I. Ogilvie

2008-03-11

39

Structural Mechanisms of Dilatometric Processes  

NASA Astrophysics Data System (ADS)

Temperature actions on metals and alloys usually stimulate the development of irreversible processes of structural evolution. Dilatometric hysteresis can be considered as the total effect of such processes. The elementary mechanisms affecting the sample size upon heating are known to be the thermal expansion of materials, the phase and structural transformations, the ductile flow under its own weight, and the creep stimulated by internal stresses. Each of these mechanisms has specific features, which are unavoidably reflected by the shape of the dilatometric curves in the corresponding temperature ranges. The thermal activation parameters of the mechanisms controlling the kinetics of the change in structural parameters and the development of the corresponding size effects have been determined by photometric analysis of structural images and directly from the dilatometric curves, and the results are discussed in this paper.

Minina, N. A.; Yermishkin, V. A.; Novikov, I. I.

2013-11-01

40

Solar Energetic Particle Trapping in the Magnetosphere: What Spectral Differences Tell Us About Mechanisms  

NASA Astrophysics Data System (ADS)

Solar energetic particles (SEPs) are protons, electrons, and heavy ions emitted from the Sun with energies spanning tens of keV to GeV. These events are of extreme importance to all space-based systems be they scientific, commercial, or security based on possible service interruptions or premature system aging due to increased radiation exposure. Importantly, solar protons can become trapped in the inner magnetosphere increasing the exposure for systems in the region. Understanding the conditions under which solar protons become trapped and untrapped in the magnetosphere and how trapping depends on the energy distribution of the SEP are the main focuses of this work. Focusing on what spectral differences between high and low latitude measurements tell us about the trapping mechanisms through comparison to geomagnetic cutoff predicted differences. Using data from NOAA POES and GPS BDD2R/CXD energetic proton instruments we explore the dynamics and particle signatures hinting at the configuration of the magnetic field allowing the protons access to regions where they are normally excluded and any rapid changes causing the protons to become trapped.

Larsen, B. A.; Engel, M. A.; Munson, C. D.; Cayton, T. E.; Morley, S.

2011-12-01

41

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

42

Theory and Simulation of Neoclassical Transport Processes, with Local Trapping  

SciTech Connect

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

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

2009-03-30

43

The Pollination Mechanism in Trigonidium obtusum Lindl (Orchidaceae: Maxillariinae): Sexual Mimicry and Trap?flowers  

PubMed Central

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

SINGER, RODRIGO B.

2002-01-01

44

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

45

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

PubMed Central

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

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

2012-01-01

46

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

47

Chemically assisted mechanical refrigeration process  

DOEpatents

There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer (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

48

Chemically assisted mechanical refrigeration process  

DOEpatents

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

49

Chemically assisted mechanical refrigeration process  

DOEpatents

There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer to form a refrigerant-solvent solution while concurrently placing the solution in heat exchange relation with a working medium to transfer energy to the working medium, said refrigerant-solvent solution exhibiting a negative deviation from Raoult's Law; reducing the pressure over the refrigerant-solvent solution in an evaporator to allow the refrigerant to vaporize and substantially separate from the solvent while concurrently placing the evolving refrigerant-solvent solution in heat exchange relation with a working medium to remove energy from the working medium to thereby form a refrigerant stream and a solvent stream; and passing the solvent and refrigerant stream from the evaporator. 5 figs.

Vobach, A.R.

1987-11-24

50

Chemically assisted mechanical refrigeration process  

DOEpatents

There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer 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

51

The mechanics of manufacturing processes  

SciTech Connect

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

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

1996-10-01

52

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

SciTech Connect

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

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

2011-03-15

53

Electrolytic trapping of iodine from process gas streams  

Microsoft Academic Search

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

D. E. Horner; J. C. Mailen; F. A. Posey

1977-01-01

54

Non-Equilibrium Cell Mechanics Studied with a Dual Optical Trap  

NASA Astrophysics Data System (ADS)

Cells communicate with their surroundings biochemically, but at the same time also sense the active and passive mechanical properties of their micro-environment. Cells can ``feel'' mechanical stress and they generate contractile forces through their acto-myosin network to actively probe the mechanical response of the material they adhere to or are embedded in. These mechanosensory interactions result in cellular responses. We have used a dual optical trap to perform force measurements on cells suspended between two fibronectin-coated beads. We analyzed the correlated fluctuations of the beads with high spatial and temporal resolution. Using a combination of active and passive microrheology, we can simultaneously determine the (non-thermal) forces generated by the cells and actively probe their visco-elastic response properties. Here, we present data on contractile forces and elastic response of 3T3 fibroblasts, demonstrating that the transmitted force depends on the trap stiffness (i.e. rigidity of the environment). Using biochemical perturbations, we have studied the contributions of different cytoskeletal elements to the active and passive mechanical properties of the cell.

Schlosser, Florian; Rehfeldt, Florian; Schmidt, Christoph F.

2012-02-01

55

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

NASA Astrophysics Data System (ADS)

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

Allersma, Miriam W.

56

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

E-print Network

Regimes of particle trapping in inductively coupled plasma processing reactors Helen H. Hwanga in a high plasma density inductively coupled plasma ICP reactor. When operating with an unbiased substrate and ther- mophoretic forces.5 High plasma density tools ( e 1011 ­1012 cm 3 ), such as inductively coupled

Kushner, Mark

57

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

PubMed

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

Lee, Meng Chuan; Wong, Hirt Yong

2014-07-01

58

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...

59

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

E-print Network

Mechanical engineering Mechanical engineering is about solving problems, designing processes, and making products to improve the quality of human life and shape the economy. Mechanical engineers apply the principles of physics, mathematics, computing and practical skills to design mechanical systems and artefacts

Waikato, University of

60

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

61

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

2012-03-20

62

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

63

A survey of process migration mechanisms  

Microsoft Academic Search

We define process migration as the transfer of a sufficient amount of a process's state from one machine to another for the process to execute on the target machine.This paper surveys proposed and implemented mechanisms for process migration. We pay particular attention to the designer's goals, such as performance, load-balancing, and reliability. The effect of operating system design upon the

Jonathan M. Smith

1988-01-01

64

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

65

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

SciTech Connect

Geologic reevaluation of the giant Kern River field, a 4 billion bbl oil accumulation, suggests a nontrapping oil emplacement mechanism not previously described in the literature. The field produces 12-14{degree} API oil from a shallow, thick sequence of stacked fluvial sands situated across a homocline that dips 4-5{degree} southwest. Migration of hydrocarbons generated in deeply buried Miocene shales ended in the Kern River field when the oil reached the top of the regional groundwater table, a surface that truncates the dipping beds in the subsurface. The oil floats on top of the groundwater and is confined by an updip seal consisting of simply gravity, or barometric pressure. Significant vertical changes in the groundwater support system in the geologic and historic past have probably been caused by climatic fluctuations or changes in the volume or location of the nearby Kern River. A recharged groundwater support system would have hydraulically lifted the floating oil into shallower sands; a depleted support system would have allowed the oil to flow downdip, leaving behind undersaturated dry oil sands. Lateral propagation of this floating oil pool is limited by the inability of the unpressured oil to overcome capillary resistances and opposing groundwater movements. Stratigraphic complexities and faulting occasionally influence oil distribution, but the upper limits of producible oil are determined by the configuration of the regional groundwater table. Other shallow, heavy San Joaquin Valley oil fields that lack definitive conventional trapping mechanisms probably can also be reclassified as floating oil pools.

Kodl, E.J. (PT Caltex Pacific Indonesia, Sumatra (Indonesia)); Eacman, J.C. (Texaco Producing, Inc., Bakersfield, CA (USA))

1990-05-01

66

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

PubMed

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

Poppinga, Simon; Joyeux, Marc

2011-10-01

67

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

68

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

69

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

2014-04-13

70

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

71

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 measure ion trapping lifetime, charging effects due to laser light incident on the trap electrodes, and the 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

72

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

73

[Probing the mechanism and Ca-DPA concentration of individual Bacillus spores using trapping and Raman spectroscopy].  

PubMed

Measuring the levels of 2,6-pyridine dicarboxylic acid (DPA) in bacteria spores could provide the information about the DPA function, resistance mechanism and the mechanism of spore germination. The authors have measured levels of Ca-DPA of individual spores of different 19 kinds of Bacillus which from different sources, species, and strains by using laser tweezers Raman spectroscopy (LTRS). Also we have verified the reproducibility of the system simultaneously. To investigate the biochemical components and structure in single spore, a Raman tweezers setup was used to record the Raman spectrum of single spore. A NIR laser beam (30 mW, 785 nm) was introduced into an inverted microscope to form a tweezers for trapping the spore suspended in water, and the Raman scatter was excited by the same beam. Raman spectra of 30 spores of 19 bacillus strains which collected from different area in China were recorded, and 100 spores of B. subtilis ACCC10243 were measured. A spore of the same strain was probed 100 times for verifying the reproducibility of the LTRS system. A Matlab 7.0 edited program and Origin 8.0 were used to process the spectral data. Because Ca-DPA is the chelate of DPA and the calcium ion, and the strongest Raman bands at 1 017 cm(-1) was from Ca-DPA component of the spore, its intensity was linearly with the Ca-DPA concentration. Therefore, the 1017 cm(-1) bands of Ca-DPA could be used as the quantitative standard peak, and then calculated the concentration of Ca-DPA could be calculated according the intensity of 1017 cm(-1) peak. The results showed that Raman spectra of single spore can reflect the characteristics information of it. The diversity of Ca-DPA levels not only happened between different species and strains of bacillus, but also happened between different individual spores in the same strains of bacillus. Conclusion from these measurements is that there is heterogeneity in different individual spores. It is convenient to trapping and collecting its Raman spectrum in water directly, and then get the information of the level of DPA, without the complex preparation of separating, purifying spores and abstracting DPA, so we predict LTRS as a high sensitivity, high accuracy, rapid and effective method in the research of individual spores. PMID:20939327

Huang, Xi; Huang, Rong-shao; Lai, Jun-zhuo; Xu, Lan-lan; Li, Yong-qing; Li, Zhen-chong; Huang, Shu-shi

2010-08-01

74

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

E-print Network

Magnetic domain walls in ferromagnetic tracks can be used to trap and transport superparamagnetic beads for lab-on-a-chip applications. Here it is shown that the magnetostatic binding between a domain wall and a superparamagnetic ...

Rapoport, Elizabeth Ashera

75

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

76

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

NASA Astrophysics Data System (ADS)

We report on the complete unfaulting mechanism of a trapped self-interstitial atom cluster in the form of a nonparallel configuration (NPC), investigated using the autonomous basin climbing (ABC) method. A detailed set of transition state atomic trajectories in the unfaulting process from the trapped to the mobile glide ?111? configuration and the corresponding potential energy landscape were identified. The breaking of the initial ring structure of the three trimers on (111) planes followed by the rotation of the ?111? crowdion in the NPC are the main rate limiting processes of the unfaulting mechanism. The effective activation barrier in the transition from the NPC to the glide ?111? configuration was calculated by combining the ABC and kinetic Monte Carlo methods and was further benchmarked against molecular dynamics (MD) simulations. The effective activation barrier was found as 0.82 eV; smaller than its previously reported value of 1.68 eV. The ABC method was confirmed to be more efficient than MD, especially for the defect structure evolution processes associated with high barriers and at low temperatures.

Fan, Yue; Kushima, Akihiro; Yildiz, Bilge

2010-03-01

77

Ion stochastic trapping and drift turbulence evolution.  

PubMed

Test modes on turbulent magnetized plasmas are studied taking into account the stochastic ion trapping or eddying that characterizes the EB drift in the background turbulence. It is shown that ion trapping provides an important physical mechanism for the complex nonlinear processes in drift turbulence evolution: generation of large-scale correlations and of zonal flow modes. PMID:23767641

Vlad, Madalina

2013-05-01

78

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

NASA Astrophysics Data System (ADS)

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

Farhat, Nabil H.; Wen, Zhimin

1995-08-01

79

Early Olfactory Processing in Drosophila: Mechanisms  

E-print Network

: the peripheral ol- factory receptor neurons and their postsynaptic targets in the antennal lobe. We now to the study of ol- factory processing in other insects--chiefly lo- custs, moths, and bees (Martin et al. 2011 in these neurons. Together, these mechanisms imply that interesting neural adaptations to environ- mental

Wilson, Rachel

80

Two size-selective mechanisms specifically trap bacteria-sized food particles  

E-print Network

the flow of dense bacterial suspensions and exclude excessively large particles from entering the pharynx before passage into the terminal bulb and intestine. Filtering occurs at each trap as bacteria- muscular tube connecting the stoma and intestine (Fig. 1A). In the anterior procorpus and anterior isthmus

Fang-Yen, Christopher

81

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

E-print Network

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

Yildiz, Bilge

82

Physics and mechanisms of dielectric trap profiling by Multi-frequency Charge Pumping (MFCP) method  

Microsoft Academic Search

Multi-frequency Charge Pumping (MFCP) is a widely used technique to characterize bulk trap distribution, NT(x, E), within the SiOx\\/high-kappa dielectric. Thus far, the theoretical interpretation of MFCP has either been based on uncritical generalization of the classical CP theory of electron-hole recombination or has been interpreted as a dasiaquasi-geometricalpsila component of CP current. Moreover, the recent literature contains variants of

M. Masuduzzaman; A. E. Islam; M. A. Alam

2009-01-01

83

Blood vessel endothelial VEGFR-2 delays lymphangiogenesis: an endogenous trapping mechanism links lymph- and angiogenesis  

PubMed Central

Angio- and lymphangiogenesis are inherently related processes. However, how blood and lymphatic vessels regulate each other is unknown. This work introduces a novel mechanism explaining the temporal and spatial relation of blood and lymphatic vessels. Vascular endothelial growth factor-A (VEGF-A) surprisingly reduced VEGF-C in the supernatant of blood vessel endothelial cells, suggesting growth factor (GF) clearance by the growing endothelium. The orientation of lymphatic sprouting toward angiogenic vessels and away from exogenous GFs was VEGF-C dependent. In vivo molecular imaging revealed higher VEGF receptor (R)-2 in angiogenic tips compared with normal vessels. Consistently, lymphatic growth was impeded in the angiogenic front. VEGF-C/R-2 complex in the cytoplasm of VEGF-Atreated endothelium indicated that receptor-mediated internalization causes GF clearance from the extracellular matrix. GF clearance by receptor-mediated internalization is a new paradigm explaining various characteristics of lymphatics. PMID:20705758

Nakao, Shintaro; Zandi, Souska; Hata, Yasuaki; Kawahara, Shuhei; Arita, Ryoichi; Schering, Alexander; Sun, Dawei; Melhorn, Mark I.; Ito, Yasuhiro; Lara-Castillo, Nuria; Ishibashi, Tatsuro

2011-01-01

84

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

85

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

86

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

87

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

PubMed

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

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

2014-10-01

88

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

89

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

90

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

91

Thermo-mechanical processing of BSCCO conductors  

SciTech Connect

The ORNL BSCCO conductor development program involves collaborations with four companies and one university. The objectives of the industrial collaborations are to: (a) to determine fabrication routes for powder-in-tube (PIT) conductor which optimize the dimensional stability of the core, the Ag/superconductor interface and texture, (b) to determine mechanical properties of individual phases present during PIT fabrication, and (c) to contribute to the ASC initiative to develop processes for use of very fine and homogeneous powders in multifilament conductors; develop chemical barrier layers for strong metal substrates for Bi-2212 conductors; develop chemically compatible strengthened substrates for use in Bi-2212 conductors fabricated by dip-coating, and to aid in determining sources of J{sub c} variability in wires prepared by Oxford; and develop thermal and mechanical processes for a continuous tubular wire fabrication method as an alternative to PIT. ORNL provides partial support for a student at the University of Wisconsin to evaluate the effects of dopants on aerosol powders for wires.

Kroeger, D.M.; Sikka, V.K. [Oak Ridge National Lab., TN (United States)

1994-07-29

92

Processing and Mechanical Properties of Baroplastics  

NASA Astrophysics Data System (ADS)

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

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

2004-03-01

93

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

E-print Network

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

94

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

95

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.

96

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

97

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

PubMed Central

Recently we showed that peroxynitrite (ONOO?) reacts directly and rapidly with aromatic and aliphatic boronic acids (k ? 106 M?1s?1). Product analyses and substrate consumption data indicated that ONOO? reacts stoichiometrically with boronates, yielding the corresponding phenols as the major product (~8590%), and the remaining products (1015%) were proposed to originate from free radical intermediates (phenyl and phenoxyl radicals). Here we investigated in detail the minor, free radical pathway of boronate reaction with ONOO?. The electron paramagnetic resonance (EPR) spin-trapping technique was used to characterize the free radical intermediates formed from the reaction between boronates and ONOO?. Using 2-methyl-2-nitrosopropane (MNP) and 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) spin traps, phenyl radicals were trapped and detected. Although phenoxyl radicals were not detected, the positive effects of molecular oxygen, and inhibitory effects of hydrogen atom donors (acetonitrile, and 2-propanol) and general radical scavengers (GSH, NADH, ascorbic acid and tyrosine) on the formation of phenoxyl radical-derived nitrated product, suggest that phenoxyl radical was formed as the secondary species. We propose that the initial step of the reaction involves the addition of ONOO? to the boron atom in boronates. The anionic intermediate undergoes both heterolytic (major pathway) and homolytic (minor pathway) cleavage of the peroxy (O-O) bond to form phenol and nitrite as a major product (via a non-radical mechanism), or a radical pair PhB(OH)2O?NO2 as a minor product. It is conceivable that phenyl radicals are formed by the fragmentation of PhB(OH)2O? radical anion. According to the DFT quantum mechanical calculations, the energy barrier for the dissociation of PhB(OH)2O? radical anion to form phenyl radicals is only a few kcal/mol, suggesting rapid and spontaneous fragmentation of PhB(OH)2O? radical anion in aqueous media. Biological implications of the minor free radical pathway are discussed in the context of ONOO? detection, using the boronate probes. PMID:21434648

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

2013-01-01

98

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

NASA Technical Reports Server (NTRS)

A theoretical model for the trap-assisted tunneling process in diffused n-on-p and implanted n(+)-on-p HgCdTe photodiodes is presented. The model describes the traps and the trap characteristics: concentration, energy level, and capture cross sections. We have observed that the above two types of diodes differ in the voltage dependence of the trap-assisted tunneling current and dynamic resistance. Our model takes this difference into account and offers an explanation of the phenomenon. The good fit between measured and calculated DC characteristics of the photodiodes (for medium and high reverse bias and for temperatures from 65 to 140 K) supports the validity of the model.

Rosenfeld, David; Bahir, Gad

1992-01-01

99

Trapping cold molecular hydrogen.  

PubMed

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

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

2011-11-14

100

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

101

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

102

A Survey of Process Migration Mechanisms Ramon Lawrence  

E-print Network

A Survey of Process Migration Mechanisms Ramon Lawrence Department of Computer Science University more resources. Load balancing and process migration allocate processes to interconnected migration mechanisms. There have been other such survey papers on process migration[13, 17], but this paper

Lawrence, Ramon

103

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

104

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

105

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

106

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

107

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

108

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

PubMed

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 k(TTF) = (5.4 0.4) 10(-10) cm(3) 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. PMID:24050320

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

2013-09-14

109

Structural changes in isometrically contracting insect flight muscle trapped following a mechanical perturbation.  

PubMed

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

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

2012-01-01

110

Charge trapping and current-conduction mechanisms of metal-oxide-semiconductor capacitors with La xTa y dual-doped HfON dielectrics  

NASA Astrophysics Data System (ADS)

Charge trapping and related current-conduction mechanisms in metal-oxide-semiconductor (MOS) capacitors with La xTa y dual-doped HfON dielectrics have been investigated under various post-deposition annealing (PDA). The results indicate that by La xTa y incorporation into HfON dielectric enhances electrical and reliability characteristics, including equivalent-oxide-thickness (EOT), stress-induced leakage current (SILC), and trap energy level. The mechanisms related to larger positive charge generation in the gate dielectric bulk can be attributed to La xTa y dual-doped HfON dielectric. The results of C- V measurement indicate that more negative charges are induced with increasing PDA temperature for the La xTa y dual-doped HfON dielectric. The charge current transport mechanisms through various dielectrics have been analyzed with current-voltage ( I- V) measurements under various temperatures. The current-conduction mechanisms of HfLaTaON dielectric at the low-, medium-, and high-electrical fields were dominated by Schottky emission (SE), Frenkel-Poole emission (F-P), and Fowler-Nordheim (F-N), respectively. A low trap energy level ( ? trap) involved in Frenkel-Pool conduction in an HfLaTaON dielectric was estimated to be around 0.142 eV. Although a larger amount of positive charges generated in the HfLaTaON dielectric was obtained, the ? trap of these positive charges in the HfLaTaON dielectric are shallow compared with HfON dielectric.

Cheng, Chin-Lung; Horng, Jeng-Haur; Chang-Liao, Kuei-Shu; Jeng, Jin-Tsong; Tsai, Hung-Yang

2010-10-01

111

Free Radical Mechanisms in Autoxidation Processes.  

ERIC Educational Resources Information Center

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

Simic, Michael G.

1981-01-01

112

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

113

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

114

Ecological and evolutionary traps  

USGS Publications Warehouse

Organisms often rely on environmental cues to make behavioral and life-history decisions. However, in environments that have been altered suddenly by humans, formerly reliable cues might no longer be associated with adaptive outcomes. In such cases, organisms can become 'trapped' by their evolutionary responses to the cues and experience reduced survival or reproduction. Ecological traps occur when organisms make poor habitat choices based on cues that correlated formerly with habitat quality. Ecological traps are part of a broader phenomenon, evolutionary traps, involving a dissociation between cues that organisms use to make any behavioral or life-history decision and outcomes normally associated with that decision. A trap can lead to extinction if a population falls below a critical size threshold before adaptation to the novel environment occurs. Conservation and management protocols must be designed in light of, rather than in spite of, the behavioral mechanisms and evolutionary history of populations and species to avoid 'trapping' them.

Schlaepfer, M.A.; Runge, M.C.; Sherman, P.W.

2002-01-01

115

Migration Processes and Mechanisms of Youth Socialization.  

ERIC Educational Resources Information Center

The dramatic changes in Bulgaria's agriculture, labor structure, and demography caused by the establishment of socialism in the country in the mid-1940s have resulted in changing mechanisms of youth socialization. Industrialization and agricultural consolidation precipitated a rural-urban migration boom and a resulting higher education level,

Mitev, Peter-Emil

116

Magnetic Trapping - Trapped Radiation  

NSDL National Science Digital Library

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

Stern, David

2005-04-27

117

Ultra-fast underwater suction traps  

PubMed Central

Carnivorous aquatic Utricularia species catch small prey animals using millimetre-sized underwater suction traps, which have fascinated scientists since Darwin's early work on carnivorous plants. Suction takes place after mechanical triggering and is owing to a release of stored elastic energy in the trap body accompanied by a very fast opening and closing of a trapdoor, which otherwise closes the trap entrance watertight. The exceptional trapping speedfar above human visual perceptionimpeded profound investigations until now. Using high-speed video imaging and special microscopy techniques, we obtained fully time-resolved recordings of the door movement. We found that this unique trapping mechanism conducts suction in less than a millisecond and therefore ranks among the fastest plant movements known. Fluid acceleration reaches very high values, leaving little chance for prey animals to escape. We discovered that the door deformation is morphologically predetermined, and actually performs a buckling/unbuckling process, including a complete trapdoor curvature inversion. This process, which we predict using dynamical simulations and simple theoretical models, is highly reproducible: the traps are autonomously repetitive as they fire spontaneously after 520 h and reset actively to their ready-to-catch condition. PMID:21325323

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

2011-01-01

118

Troubleshooting in Mechanics: A Heuristic Matching Process  

Microsoft Academic Search

This paper deals with expert operators' reasoning processes in trouble-shooting. We want to know more about the information that experienced operators use. In a previous study (Besnard & Bastien-Toniazzo, 1999; Besnard, 2000), we studied electronics trouble- shooting. We found that experts used surface cues in order to implement heuristic rules even if the latter are not relevant to the current

Denis Besnard; Lucile Cacitti

2001-01-01

119

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

120

Particle trapping with an rf cavity  

SciTech Connect

It is in principle possible to trap charged particles in an rf cavity. In this note the authors calculate the trapping mechanism of the field pattern given by (1). The trapping occurs for either sign of the charge of the particles. The mode pattern (1) traps particles around the node point (0,0,0). Such a trapping mechanism is of course considered favorable for a particle trap. On the other hand, it may also happen that undesirable stray particles are trapped at nodes of an rf device, which then perturbs the normal operation of an accelerator. Such trappings are then undesirable and are to be avoided.

Chao, A.

1995-11-01

121

Representing SN1 Reaction Mechanism Using the Qualitative Process Theory  

E-print Network

Representing SN1 Reaction Mechanism Using the Qualitative Process Theory Alicia Tang Y. This paper presents an account for the design of qualitative models for the SN1 reaction mechanism using QPT students stumbled on the understanding of organic reaction mechanisms such the SN1 (unimolecular

Bailey-Kellogg, Chris

122

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

123

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

124

Respiratory fluid mechanics and transport processes.  

PubMed

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

Grotberg, J B

2001-01-01

125

Laser hardening process simulation for mechanical parts  

NASA Astrophysics Data System (ADS)

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

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

2007-02-01

126

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

NASA Astrophysics Data System (ADS)

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

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

2007-09-01

127

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

128

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

129

Trapping Coyotes  

E-print Network

, small bushes, animal carcasses, skeletons or other objects. Often there are scratch marks near a scent post which help identify it. Natural scent posts or ones created by a trapper are good loca- tions for trap sets. Trap Sets There are several types... covered with dirt or grass. Any remaining dirt can be scattered away from the holetomakeitappearthatananimalhasdugthe hole. Guided by the coyote sign present, the trap- per should carefully examine the area for good trapsites...

Texas Wildlife Services

2008-04-15

130

Optical trapping  

PubMed Central

Since their invention just over 20 years ago, optical traps have emerged as a powerful tool with broad-reaching applications in biology and physics. Capabilities have evolved from simple manipulation to the application of calibrated forces onand the measurement of nanometer-level displacements ofoptically trapped objects. We review progress in the development of optical trapping apparatus, including instrument design considerations, position detection schemes and calibration techniques, with an emphasis on recent advances. We conclude with a brief summary of innovative optical trapping configurations and applications. PMID:16878180

Neuman, Keir C.; Block, Steven M.

2006-01-01

131

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

132

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

133

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

134

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; Hulskamp, Martin

2008-01-01

135

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

136

ThermoMechanical Processing and Properties of a Ductile Iron  

Microsoft Academic Search

Thermo-mechanical processing of ductile irons is a potential method for enhancing their mechanical properties. A ductile cast iron containing 3.6% C, 2.6% Si and 0.045% Mg was continuously hot-and-warm rolled or one-step press-forged from a temperature in the austenite range (900°C-1100°C) to a temperature below the A, temperature. Various amounts of reduction were used (from 60% to more than 90%)

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

1997-01-01

137

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

...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...

2014-07-01

138

Improving Software Development Process through Economic Mechanism Design  

NASA Astrophysics Data System (ADS)

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

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

139

Investigating of electrons bunching in a Penning trap and accelerating process for CO2 gas mixture active medium  

E-print Network

In the presence of an active medium incorporated in a Penning trap, the moving electrons can become bunched, as they get enough energy, they escape the trap forming an optical injector. These bunched electrons can enter next PASER section filled with the same active medium to be accelerated. In this paper, electron dynamics in the presence of gas mixture active medium incorporated in a penning trap is analyzed by developing an idealized 1D model. We further evaluate the energy exchange occurring as the train of electrons traversing the next PASER section. The results show that the oscillating electrons can be bunched at the resonant frequency of the active medium. The influence of the trapped time and the population inversion are analyzed, which shows that the longer the electrons are trapped, the more energy from the medium the accelerated electrons get, and with the increase of the population inversion, the decelerated electrons virtually unchanged but the accelerated electrons more than double their peak e...

Tian, Xiu-fang; Jia, Qika

2014-01-01

140

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

PubMed

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

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

2014-01-23

141

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

PubMed Central

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

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

2014-01-01

142

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

143

Kinetics of charge trapping in dielectrics  

NASA Astrophysics Data System (ADS)

Transient electronic conduction in thermally grown SiO2 has been shown to be limited by space-charge evolution. The space charge originates from trapping of the injected species. It induces a field which affects the emission of charges at the injecting electrode. The trapping of charge has been analyzed on the basis of three, essentially different, mechanisms: (1) first order trapping, (2) first order trapping which takes into account that trapped charges repel injected charges, and (3) trapping which increases during injection due to the generation of states. It is shown that implementation of the three trapping mechanisms yields a current versus injected charge plot which is given in the asymptotes by simple logarithmic functions. Intersection of the asymptotes directly yields the value of the capture cross section. From the slopes of the asymptotes the surface density(ies) of the trap(s) can be calculated. The method can be used without, a priori, assuming either the injection mechanism or the trapping mechanism. From the relative position of the intersection points the applicable mechanism can be derived, however. For thermal SiO2 on Si we determined, by this method, values of trap densities and capture cross sections which are typical for water-related traps. Furthermore, we derived that trapping mechanism (2) fits our data best.

Wolters, D. R.; van der Schoot, J. J.

1985-07-01

144

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

145

Thermoplastics as engineering materials: The mechanics, materials, design, processing link  

Microsoft Academic Search

While the use of plastics has been growing at a significant pace because of weight reduction, ease of fabrication of complex shapes, and cost reduction resulting from function integration, the engineering applications of plastics have only become important in the past fifteen years. An inadequate understanding of the mechanics issues underlying the close coupling among the design, the processing (fabrication),

Vijay K. Stokes

1995-01-01

146

Treating process wastewater employing vacuum distillation using mechanical vapor recompression  

Microsoft Academic Search

Process wastewater has been successfully treated using an enhanced variable vacuum distillation system (VVDS). The removal of contaminants is achieved initially by degassing the liquid under an intense vacuum which removes the volatile organic compounds. The resulting liquid is then distilled under a vacuum using mechanical vapor recompression. The system was invented by Derald McCabe. This innovative treatment system removes

Derald L. McCabe

1999-01-01

147

Passivation mechanisms in cryogenic SF6\\/O2 etching process  

Microsoft Academic Search

Passivation mechanisms of Si trenches involved in SF6\\/O2 cryogenic plasma etching were investigated in order to better control the process and avoid defects. Trench sidewalls and profiles were ex situ characterized geometrically by SEM and chemically by spatially resolved XPS experiments. These measurements reveal that the passivating layer is removed during the increase of the wafer chuck temperature leading to

R. Dussart; M. Boufnichel; G. Marcos; P. Lefaucheux; A. Basillais; R. Benoit; T. Tillocher; X. Mellhaoui; H. Estrade-Szwarckopf; P. Ranson

2004-01-01

148

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

149

Magneto-optical Trapping of Cadmium  

E-print Network

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

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

2007-01-01

150

Interface trap generation and recovery mechanisms during and after positive bias stress in metal-oxide-semiconductor structures  

NASA Astrophysics Data System (ADS)

Interface trap (Nit) generation and their partial recovery during and after cessation of the positive bias-temperature stress (PBTS) in n-type metal-oxide-semiconductor capacitors have been investigated. The analysis of experimental results indicates that Nit creation is caused by the depassivation of Si3?Si -H bonds at the Si/SiO2 interface by the atomic neutral hydrogen (H0) cracked via electron impact at or near gate/oxide interface during electron injection from the substrate. Nit recovery after interruption of the stress is due to back diffusion of H2 species toward the Si/SiO2 interface and repassivation of Si3?Si dangling bonds. We propose that in absence of holes, a modified one dimensional reaction-diffusion (R-D) model following three step degradation sequences can qualitatively explain the generation and the recovery of Nit during and after PBTS.

Samanta, Piyas; Huang, Heng-Sheng; Chen, Shuang-Yuan; Tzeng, Tsung-Jian; Wang, Mu-Chun

2012-05-01

151

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

152

Hemispheric differences in the recruitment of semantic processing mechanisms  

PubMed Central

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 (LPC), linked to controlled aspects of processing, showed that previously documented left hemisphere (LH) processing benefits for word pairs with a weak forward but strong backward association stem from the ability to appreciate meaning relations in an order-independent fashion and/or strategically reorder them. Whereas there is a LH benefit for such strategic processing during comprehension in passive tasks, the present study further showed that the RH is also able to make use of these mechanisms when explicit semantic judgments are required. In both hemispheres, N400 responses, linked to initial semantic activation, were largely graded by association strength, with more amplitude reduction for forward associates and strong, symmetrically associated pairs compared to backward associates and matched weak, symmetrically associated pairs. However, responses to moderately associated pairs were more facilitated after initial presentation to the LH than to the RH. This pattern converges with sentence processing findings that point to LH advantages for using context information to predict features of likely upcoming words. Together, the results suggest that an important basis for hemispheric asymmetries in language comprehension arises from when and how each uses top-down semantic mechanisms to shape initial semantic activation over time. PMID:20638397

Kandhadai, Padmapriya; Federmeier, Kara D.

2010-01-01

153

An improved numerical process for solution of solid mechanics problems  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

154

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

Code of Federal Regulations, 2013 CFR

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

2013-10-01

155

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

156

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

157

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

Code of Federal Regulations, 2012 CFR

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

2012-10-01

158

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

159

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

160

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

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

2014-07-01

161

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

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

2014-07-01

162

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

SciTech Connect

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

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

2003-08-01

163

Quantum processes as a mechanism in olfaction for smell recognition?  

NASA Astrophysics Data System (ADS)

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

Brookes, Jennifer

2011-03-01

164

Kinetic process of mechanical alloying in Fe50Cu50  

NASA Astrophysics Data System (ADS)

It is shown that mechanical alloying in the immiscible Fe-Cu system is governed by the atomic shear event and shear-induced diffusion process. We found that an ?-to-? phase transformation, as evidenced by the Nishiyama-Wasserman orientation relationship, occurs by simultaneous shearing process when the grain size reduces to about 20 nm and Cu content reaches 20 at. % in bcc-FerichCu grains in the intermediate stage of milling of Fe50Cu50. Further milling promotes the interdiffusion between fcc-FerichCu and fcc-FeCurich, which is favored because of the similarity of the lattice structures, until a complete fcc Fe-Cu solid solution is formed. The results provide significant insight into the understanding of recent experiments showing that chemical mixing of immiscible elements can be induced by mechanical alloying.

Huang, J. Y.; Jiang, J. Z.; Yasuda, H.; Mori, H.

1998-11-01

165

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

NASA Technical Reports Server (NTRS)

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

Iskenderian, Ted

2004-01-01

166

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

167

Network Modeling of EOR Processes: A Combined Invasion Percolation and Dynamic Model for Mobilization of Trapped Oil  

Microsoft Academic Search

A novel concept for modeling pore-scale phenomena included in several enhanced oil recovery (EOR) methods is presented. The\\u000a approach combines a quasi-static invasion percolation model with a single-phase dynamic transport model in order to integrate\\u000a mechanistic chemical oil mobilization methods. A framework is proposed that incorporates mobilization of capillary trapped\\u000a oil. We show how double displacement of reservoir fluids can

S. F. Bolandtaba; A. Skauge

168

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

169

Experimental analysis of the magnetic field shielding and trapping properties of bulk, melt-processed YBa2Cu3O7-?  

NASA Astrophysics Data System (ADS)

A scanning Hall probe has been used to map the distribution of magnetic field in melt-processed YBa2Cu3O7-? (YBCO) discs prepared by seeded and controlled molten-zone techniques. Both shielded and trapped fields were studied as a function of applied magnetic field for each specimen. A clear four-fold symmetry has been observed in the field distribution of the seeded melt-processed sample, suggesting that there are two planes in the disc which exhibit a weak response to an applied field. Similar magnetic properties were observed for the molten-zone processed sample and attributed to the presence of cracks in the specimen. It was found that the applied field required to saturate each sample was much higher than the maximum observed trapped field, in contradiction to the Bean model for a slab geometry. This effect, which is probably due to the plate geometry of the specimens and the variation of critical current density with magnetic field, has implications for practical applications of bulk melt-processed YBCO.

Cardwell, D. A.; Jiang, X. H.; Astill, D. M.; Lo, W.; Coombs, T. A.; Campbell, A. M.; Larsen, J. G.

1995-02-01

170

Experimental analysis of the magnetic field shielding and trapping properties of bulk melt-processed YBa 2Cu 3O 7-?  

NASA Astrophysics Data System (ADS)

A scanning Hall probe has been used to map the distributions of magnetic field in melt-processed YBa 2Cu 3O 7-? (YBCO) discs prepared by seeded and controlled molten-zone techniques. Both shielded and trapped fields were studied as a function of applied magnetic field for each speciment. A clear four-fold symmetry has been observed in the field distribution of the seeded melt-processed sample, suggesting that there are two planes in the disc which exhibit a weak response to an applied field. Similar magnetic properties were observed for the molten-zone processed sample and attributed to the presence of cracks in the specimen. It was found that the applied field required to saturate each sample was much higher than the maximum observed trapped field, in contradiction to the Bean model for a slab geometry. This effect, which is probably due to the plate geometry of the specimens and the variation of critical current density with magnetic field, has implications for practical applications of bulk melt-processed YBCO.

Jiang, X. H.; Astill, D. M.; Lo, W.; Cardwell, D. A.; Coombs, T. A.; Campbell, A. M.; Larsen, J. G.

171

Mechanisms of folate losses during processing: diffusion vs. heat degradation.  

PubMed

Though folates are sensitive to heat treatments, leaching appears to be a major mechanism involved in folate losses in vegetables during processing. The aim of our study was to study folate diffusivity and degradation from spinach and green beans, in order to determine the proportion of each mechanism involved in folate losses. Folate diffusivity constant, calculated according to Fick's second law (Crank, 1975), was 7.410(-12) m(2)/s for spinach and 5.810(-10) m(2)/s for green beans, which is the same order of magnitude as for sugars and acids for each vegetable considered. Folate thermal degradation kinetics was not monotonous in spinach and green beans especially at 45 C and did not follow a first order reaction. The proportion of vitamers changed markedly after thermal treatment, with a better retention of formyl derivatives. For spinach, folate losses were mainly due to diffusion while for green beans thermal degradation seemed to be preponderant. PMID:24679802

Delchier, Nicolas; Ringling, Christiane; Maingonnat, Jean-Franois; Rychlik, Michael; Renard, Catherine M G C

2014-08-15

172

Cotranslational processing mechanisms: towards a dynamic 3D model.  

PubMed

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

Giglione, Carmela; Fieulaine, Sonia; Meinnel, Thierry

2009-08-01

173

Random telegraph signal noise mechanisms in reverse base current of hot carrier-degraded submicron bipolar transistors: Effect of carrier trapping during stress on noise characteristics  

NASA Astrophysics Data System (ADS)

We investigate physical mechanisms of random telegraph signal (RTS) noise in reverse base current of hot carrier-degraded polysilicon emitter bipolar junction transistors. RTS noise, analyzed in the time domain, is studied as a function of reverse base-emitter bias, temperature, and additional reverse-bias stress. Two-level RTS with a relative amplitude as high as 100% is observed at room temperature. The RTS amplitude varies exponentially with the applied reverse base-emitter voltage and depends weakly on temperature. The additional hot carrier stress is observed to induce changes in RTS amplitude and mean pulse widths (independent or correlated), and a disappearance/reappearance of the RTS fluctuations. The results are interpreted by a model where the RTS noise is caused by fluctuations of generation-recombination (g-r) parameters (i.e., capture cross sections and energy position in the gap) of a stress-induced complex bistable defect (CBD) at the Si/SiO2 interface. The complex defect is assumed to be either a two-state fast interface state or an interacting pair of a fast interface state with a slow neighboring border trap. The RTS amplitude is well explained by fluctuations in a single-defect electric-field-enhanced g-r rate between a finite value and naught. The RTS amplitude-bias characteristics and their temperature dependence are satisfactorily accounted for by an expression for a phonon-assisted tunneling current via a single deep-level state. The model parameters are the g-r parameters of the defect and its spatial position in the base-emitter p-n junction. The stress-induced changes in the RTS noise are attributed to the influence of log-time trapping of hot carriers on border states laying in the vicinity of a CBD center. The charged border traps interact with a CBD, changing both its g-r parameters and the RTS switching behavior. The variations in RTS parameters are related to the microscopic nature of the interaction and are discussed for the two types of the CBDs.

Pogany, D.; Chroboczek, J. A.; Ghibaudo, G.

2001-04-01

174

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

175

Modeling morphology evolution and mechanical behavior during thermo-mechanical processing of semi-crystalline polymers  

NASA Astrophysics Data System (ADS)

A new model is proposed that combines statistical mechanics and thermodynamic aspects to characterize orientation development, nucleation and growth of crystallites, and chain entanglement slippage with interdependent relationships necessary to accurately correlate and in some cases predict the morphology and mechanical behavior of semi-crystalline polymers during various thermo-mechanical processes in the rubbery state, close to the glass transition temperature. Internal state variables (ISVs) that directly represent the underlying microstructure state are used to characterize polymer morphology and the resulting properties throughout deformation. The model uses fundamental thermodynamic coefficients for polyethylene terephthalate (PET) and is correlated to experimental data at various strain rates and temperatures just above the glass transition temperature. Experimental data are used that measure the stress, amorphous orientation, and crystallinity during uniaxial deformation of PET. The model is found to correlate well to these experimental data.

Shepherd, James E.; McDowell, David L.; Jacob, Karl I.

2006-03-01

176

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

177

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

178

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

179

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

180

A method for trapping breeding adult American Oystercatchers  

USGS Publications Warehouse

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

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

2005-01-01

181

Covalent Intermediate in the Catalytic Mechanism of the Radical SAM Methyl Synthase RlmN Trapped by Mutagenesis  

PubMed Central

The posttranscriptional modification of ribosomal RNA (rRNA) modulates ribosomal function and confers resistance to antibiotics targeted to the ribosome. The radical SAM (S-adenosyl-L-methionine) methyl synthases, RlmN and Cfr, both methylate A2503 within the peptidyl transferase center (PTC) of prokaryotic ribosomes, yielding 2-methyl- and 8-methyl-adenosine, respectively. The C2 and C8 positions of adenosine are unusual methylation substrates due to their electrophilicity. To accomplish this reaction, RlmN and Cfr proceed by a shared radical-mediated mechanism. However, in addition to the radical SAM CX3CX2C motif, both RlmN and Cfr contain two conserved cysteine residues required for in vivo function. These conserved cysteine residues are putatively involved in a covalent intermediate employed by RlmN and Cfr in order to achieve this challenging transformation. Currently, there is no direct evidence for this proposed covalent intermediate. We have further investigated the roles of these conserved cysteines in the mechanism of RlmN. Cysteine 118 mutants of RlmN are unable to resolve the covalent intermediate, either in vivo or in vitro, enabling us to isolate and characterize this intermediate. Additionally, tandem mass spectrometric analyses of mutant RlmN reveal a methylene-linked adenosine modification at cysteine 355. Employing deuterium-labeled SAM and RNA substrates in vitro has allowed us to further elucidate the mechanism of formation of this intermediate. Together, these experiments provide compelling evidence for the formation of a covalent intermediate species formed between RlmN and its rRNA substrate and the roles of the conserved cysteine residues in catalysis. PMID:23088750

McCusker, Kevin P.; Medzihradszky, Katalin F.; Shiver, Anthony L.; Nichols, Robert J.; Yan, Feng; Maltby, David A.; Gross, Carol A.; Fujimori, Danica Galonic

2012-01-01

182

Dissociation of neural mechanisms underlying orientation processing in humans  

PubMed Central

Summary Orientation selectivity is a fundamental, emergent property of neurons in early visual cortex, and discovery of that property [1, 2] dramatically shaped how we conceptualize visual processing [36]. However, much remains unknown about the neural substrates of these basic building blocks of perception, and what is known primarily stems from animal physiology studies. To probe the neural concomitants of orientation processing in humans, we employed repetitive transcranial magnetic stimulation (rTMS) to attenuate neural responses evoked by stimuli presented within a local region of the visual field. Previous physiological studies have shown that rTMS can significantly suppress the neuronal spiking activity, hemodynamic responses, and local field potentials within a focused cortical region [7, 8]. By suppressing neural activity with rTMS, we were able to dissociate components of the neural circuitry underlying two distinct aspects of orientation processing: selectivity and contextual effects. Orientation selectivity gauged by masking was unchanged by rTMS, whereas an otherwise robust orientation repulsion illusion was weakened following rTMS. This dissociation implies that orientation processing relies on distinct mechanisms, only one of which was impacted by rTMS. These results are consistent with models positing that orientation selectivity is largely governed by the patterns of convergence of thalamic afferents onto cortical neurons, with intracortical activity then shaping population responses contained within those orientation-selective cortical neurons. PMID:19682905

Ling, Sam; Pearson, Joel; Blake, Randolph

2009-01-01

183

Microdamage: a cell transducing mechanism based on ruptured osteocyte processes.  

PubMed

As a result of underlying pathological diseases, such as osteoporosis, osteopenia, or due to altered loading after joint replacements, bones become more susceptible to microdamage accumulation than those of normal human beings, as are those of athletes who undertake strenuous exercise [Stromsoe, 2004. Fracture fixation problems in osteoporosis. Injury 35, 107-113]. Experimental evidence has linked bone adaptation to microdamage, and to increased cell activity. In this work, we investigated whether microcrack detection is related to rupturing of the cellular material itself due to crack face displacements. Using specific cell staining techniques, it was confirmed that relative crack displacements are capable of tearing cell processes between neighbouring osteocytes. No ruptured cell processes were found near the crack tip where the displacements are less. Rupturing of cell processes due to crack opening and shear displacement is a feasible new mechanism by which bone can detect and estimate the size of a microcrack. Ruptured cell processes may directly secrete passive and active components in the extracellular matrix, triggering a repair response. PMID:16112124

Hazenberg, Jan G; Freeley, Michael; Foran, Eilis; Lee, Thomas C; Taylor, David

2006-01-01

184

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

185

Treating process wastewater employing vacuum distillation using mechanical vapor recompression  

SciTech Connect

Process wastewater has been successfully treated using an enhanced variable vacuum distillation system (VVDS). The removal of contaminants is achieved initially by degassing the liquid under an intense vacuum which removes the volatile organic compounds. The resulting liquid is then distilled under a vacuum using mechanical vapor recompression. The system was invented by Derald McCabe. This innovative treatment system removes virtually all of the contaminants, such as TSS, TDS, BOD{sub 5}, COD, heavy metals and mineral compounds. The resultant aqueous portion normally returns to a neutral pH. Due to the unique system operation, scaling problems (often encountered in conventional distillation) have not been detected in this system. The VVDS is extremely energy efficiency because the heat for distillation is generated and recycled mechanically. Using electricity as the energy source, the approximate operating cost, based on $0.05 KWH, may vary from $0.005 to $0.01 per gallon depending on the size and capacity of the equipment. Based on applications in waste streams performed to-date, the VVDS process has yielded a distilled water stream and the concentrated solids have been used as a byproduct or as a concentrated non-dischargeable waste for disposal.

McCabe, D.L. [Brandt, Houston, TX (United States)] [Brandt, Houston, TX (United States); Vivona, M.A. [ICF Kaiser Engineers, Inc., Houston, TX (United States). Water and Wastewater Dept.] [ICF Kaiser Engineers, Inc., Houston, TX (United States). Water and Wastewater Dept.

1999-05-01

186

Development of brain mechanisms for processing affective touch  

PubMed Central

Affective tactile stimulation plays a key role in the maturation of neural circuits, but the development of brain mechanisms processing touch is poorly understood. We therefore used functional magnetic resonance imaging (fMRI) to study brain responses to soft brush stroking of both glabrous (palm) and hairy (forearm) skin in healthy children (513 years), adolescents (1417 years), and adults (2535 years). Adult-defined regions-of-interests in the primary somatosensory cortex (SI), secondary somatosensory cortex (SII), insular cortex and right posterior superior temporal sulcus (pSTS) were significantly and similarly activated in all age groups. Whole-brain analyses revealed that responses in the ipsilateral SII were positively correlated with age in both genders, and that responses in bilateral regions near the pSTS correlated significantly and strongly with age in females but not in males. These results suggest that brain mechanisms associated with both sensory-discriminative and affective-motivational aspects of touch are largely established in school-aged children, and that there is a general continuing maturation of SII and a female-specific increase in pSTS sensitivity with age. Our work establishes a groundwork for future comparative studies of tactile processing in developmental disorders characterized by disrupted social perception such as autism. PMID:24550800

Bjornsdotter, Malin; Gordon, Ilanit; Pelphrey, Kevin A.; Olausson, Hakan; Kaiser, Martha D.

2014-01-01

187

Mechanical model of precursory source processes for some large earthquakes  

SciTech Connect

A mechanical model is presented of precursory source processes for some large earthquakes along plate boundaries. It is assumed that the pre-seismic period consists of the upward progression of a zone of slip from lower portions of the lithosphere towards the Earth's surface. The slip front is blocked by local asperities of different size and strength; these asperities may be zones of real alteration of inherent strength, or instead may be zones which are currently stronger due to a local slowdown of a basically rate-dependent frictional response. Such blocking by a single, large asperity, or array of asperities, produces quiescence over a segment of plate boundary, until gradual increase of the stress concentration forces the slip zone through the blocked region at one end of the gap, thus nucleating a seismic rupture that propogates upwards and towards the other end. This model is proposed to explain certain distinctive seismicity patterns that have been observed before large earthquakes, notably quiescence over the gap zone followed by clustering at its end prior to the main event. A discussion of mechanical factors influencing the process is presented and some introductory modelling, performed with the use of a generalized Elsasser model for lithospheric plates and the ''line spring'' model for part-through flaws (slip zones) at plate boundaries, is outlined briefly.

Dmorvska, R.; Li, V.C.

1982-04-01

188

Trapped particle absorption by the ring of Jupiter  

NASA Technical Reports Server (NTRS)

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

Fillius, W.

1985-01-01

189

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

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

2014-01-01

190

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

Code of Federal Regulations, 2013 CFR

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

2013-01-01

191

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

Code of Federal Regulations, 2010 CFR

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

2010-01-01

192

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

Code of Federal Regulations, 2011 CFR

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

2011-01-01

193

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

Code of Federal Regulations, 2012 CFR

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

2012-01-01

194

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

195

Brain mechanisms associated with top-down processes in perception.  

PubMed Central

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

Frith, C; Dolan, R J

1997-01-01

196

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

197

Injection into electron plasma traps  

SciTech Connect

Computational studies and experimental measurements of plasma injection into a Malmberg-Penning trap reveal that the number of trapped particles can be an order of magnitude higher than predicted by a simple estimates based on a ballistic trapping model. Enhanced trapping is associated with a rich nonlinear dynamics generated by the space-charge forces of the evolving trapped electron density. A particle-in-cell simulation is used to identify the physical mechanisms that lead to the increase in trapped electrons. The simulations initially show strong two-stream interactions between the electrons emitted from the cathode and those reflected off the end plug of the trap. This is followed by virtual cathode oscillations near the injection region. As electrons are trapped, the initially hollow longitudinal phase-space is filled, and the transverse radial density profile evolves so that the plasma potential matches that of the cathode. Simple theoretical arguments are given that describe the different dynamical regimes. Good agreement is found between simulation and theory.

Gorgadze, Vladimir; Pasquini, Thomas A.; Fajans, Joel; Wurtele, Jonathan S.

2003-12-02

198

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

199

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

200

Mechanism of Processive Movement of Monomeric and Dimeric Kinesin Molecules  

PubMed Central

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

Xie, Ping

2010-01-01

201

Probabilistic structural mechanics research for parallel processing computers  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

202

Thermo-mechanical process for treatment of welds  

SciTech Connect

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

Malik, R.K.

1980-03-01

203

Simulation aided testing of hydro-mechanical processes on clay  

NASA Astrophysics Data System (ADS)

This paper presents a study focused on the hydro-mechanical behaviour of a plastic clay under partially saturated conditions. Clay remoulded samples were dried using vapour transfer under one-dimensional conditions. Samples underwent an important vertical shrinkage on drying, which progressed along more than one week. To study the time evolution of this phenomenon, simulation aided techniques were used to analyse the progression of suction at local scale and to determine the time required to equilibrate homogeneously the sample. In this case the fully coupled thermo-hydromechanical finite element code Code_Bright [1] was used to analyse this process. The simulation adequately followed the evolution of sample shrinkage measured experimentally. The determination of the suction equalisation time also agreed with the experimental information.

Merchn, V.; Romero, E.; Vaunat, J.

2010-06-01

204

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

205

Mechanism of Action of a Palladium Modifier on Atomization Processes  

NASA Astrophysics Data System (ADS)

We have demonstrated a desorption mechanism for dissipation of palladium from a palladium modifier in a graphite furnace during sample atomization. We have carried out mathematical modeling with the aim of obtaining the most important kinetic parameters of the atomization processes: diffusion rate and energy of formation of free atoms. The energy of formation of free silver atoms in the presence of palladium, calculated from the shape of the signals, increases from 118.5 6.3 to 199.5 8.4 kJ/mol, while the activation energy for diffusion of silver in the graphite of the furnace walls increases from 75.6 1.1 to 135.2 6.0 kJ/mol, which suggests direct chemical reaction between palladium and silver.

Rogulsky, Yu. V.; Illiashenko, V. Yu.; Kulik, A. N.

2014-01-01

206

Qualitative Assessment of Flow and Transport Mechanisms in Bioremediation Processes  

NASA Astrophysics Data System (ADS)

Recent studies suggest that time-lapse crosshole geophysical methods may be effective in monitoring subsurface hydrological and biochemical mechanisms. These methods have potential to provide a minimally invasive, cost-effective, high resolution, field relevant means to gain information previously limited to wellbore data. Our study area is located at a DOE Hanford site, an area heavily polluted with toxic chromate. Time- lapse crosshole seismic and radar data sets have been collected in order to monitor spatio-temporal responses to these processes. Before using these data for parameter estimation and monitoring hydrobiogeochemical processes, we need to 1) identify the critical parameters involved in these processes; 2) determine the sensitivity of seismic/radar responses to these parameters; and 3) choose the most appropriate forward modeling approach for forward and inverse modeling. In this study, we treat critical parameters (e.g., hydraulic conductivity, flow rate, and the dispersion coefficients) as random variables, which can be described by their probabilistic density distributions. Then we adopt stochastic sampling method within the Minimum relative entropy (MRE) framework to generate many realistic models based on the welllog data. From here, the geophysical (crosshole seismic and radar) responses are computed using different forward models to study the sensitivity of the responses to those aforementioned parameters, and the performances of the different forward modeling approaches are compared. Finally, geophysical data are used for hydrobiogeochemical parameter estimation through Bayesian inverse modeling. Our study provides guidance on favorable situations in which borehole geophysical data can be effectively used for monitoring subsurface hydrobiogeochemical processes.

Terry, N.; Hou, Z.

2008-12-01

207

Dual-Pitch Processing Mechanisms in Primate Auditory Cortex  

PubMed Central

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 used by the auditory system to extract pitch are still being debated. Theoretically, pitch can be computed using either spectral or temporal acoustic features of a sound. We have investigated how cues derived from the temporal envelope and spectrum of an acoustic signal are used for pitch extraction in the common marmoset (Callithrix jacchus), a vocal primate species, by measuring pitch discrimination behaviorally and examining pitch-selective neuronal responses in auditory cortex. We find that pitch is extracted by marmosets using temporal envelope cues for lower pitch sounds composed of higher-order harmonics, whereas spectral cues are used for higher pitch sounds with lower-order harmonics. Our data support dual-pitch processing mechanisms, originally proposed by psychophysicists based on human studies, whereby pitch is extracted using a combination of temporal envelope and spectral cues. PMID:23152599

Bendor, Daniel; Osmanski, Michael S.

2012-01-01

208

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

209

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

SciTech Connect

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

Breitenfeldt, M.; Schweikhard, L. [Institut fuer Physik, Ernst-Moritz-Arndt-Universitaet, D-17487 Greifswald (Germany); Audi, G.; Lunney, D.; Naimi, S. [CSNSM-IN2P3-CNRS, F-91405 Orsay-Campus (France); Beck, D.; Herfurth, F. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstrasse 1, D-64291 Darmstadt (Germany); Blaum, K. [Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany); Ruprecht-Karls-Universitaet, Institut fuer Physik, D-69120 Heidelberg (Germany); George, S. [Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany); Institut fuer Physik, Johannes Gutenberg-Universitaet, D-55128 Mainz (Germany); Herlert, A.; Kowalska, M. [CERN, Physics Department, 1211 Geneva 23 (Switzerland); Kellerbauer, A. [Commission of the European Communities, Joint Research Center, European Institute for Transuranium Elements, D-76125 Karlsruhe (Germany); Kluge, H.-J. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstrasse 1, D-64291 Darmstadt (Germany); Ruprecht-Karls-Universitaet, Institut fuer Physik, D-69120 Heidelberg (Germany); Neidherr, D. [Institut fuer Physik, Johannes Gutenberg-Universitaet, D-55128 Mainz (Germany); Schatz, H. [NSCL, Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, Michigan 48824 (United States); Schwarz, S. [NSCL, Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States)

2009-09-15

210

Mechanisms of placement and stability of dry process shotcrete  

NASA Astrophysics Data System (ADS)

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 the properties of fresh dry-mix shotcrete in order to better understand its behaviour, or its shootability. Shootability is defined by the ease and efficiency with which a shotcrete mix can be placed; the main parameters which characterise shootability are rebound, maximum buildup thickness and reinforcement encasement. To understand and control these characteristics requires an understanding of the mechanisms involved in the placement and the stability of a shotcrete layer. These mechanisms involve both rheological and mechanical concepts: the dynamic placement of the material, without external vibration, implies high shear rates, whereas the in-place stability of the fresh material is more closely related to plasticity in terms of shear resistance. The consistency of fresh dry-mix shotcrete is considerably stiffer than that of conventional concrete, and therefore special apparatus and new testing procedures had to be created or adapted to evaluate the fresh properties of this unique material. The tests included the penetration test, fresh tensile strength test and fresh shear strength test. These tests along with detailed analysis of the in-place proportions of the mixtures helped to provide an understanding of the mechanisms needed to optimise the shootability of dry-mix shotcrete. Apart from the properties related to shootability, fundamental properties such as the yield value, the cohesion and the angle of friction were also determined. Additional information has also been gathered on the fresh dynamic properties of shotcrete, which are especially important in understanding the factors affecting the sound placement of a layer of shotcrete. Finally, a set of clear recommendations is proposed in view of the knowledge and information gathered concerning future avenues of research and development.

Jolin, Marc

211

Principles of an enhanced MBR-process with mechanical cleaning.  

PubMed

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

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

2011-01-01

212

Melt processing and mechanical properties of polyolefin block copolymers  

NASA Astrophysics Data System (ADS)

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

Phatak, Alhad

213

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

214

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

215

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

216

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

NASA Astrophysics Data System (ADS)

Processes for fabricating a Ni nanocrystal (NC)-assisted low-temperature polycrystalline silicon thin film transistor (LTPS-TFT) nonvolatile memory device of noble stack below 600 C were successfully developed. The NCs were fabricated in H-plasma atmosphere by heating a nanosized Ni film to realize an appropriate nanoparticle distribution. Results show that NCs with a number density of ?51011 cm-2 and a particle diameter of 4 to 12 nm can successfully be fabricated as charge-trapping centers for enhancing the device performance. The results also indicate that the data retentions at the initial time and after 104 s for a SiO2/Ni-NCs/Si3N4/SiO2 gate under the present stack of devices are about 2.2 and ?1.1 V, respectively.

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

2010-06-01

217

Vortex process for capturing mechanical energy during upward heat-convection in the atmosphere  

Microsoft Academic Search

Mechanical energy is produced when heat is carried upward by convection in the atmosphere. Processes for controlling and concentrating where the mechanical energy is produced could be a method of harnessing solar energy. A process for producing and controlling a tornado-like vortex and thereby concentrating the mechanical energy where it can be captured is proposed. The vortex process is compared

L. M. Michaud

1999-01-01

218

Part III. (4) Mechanical and Thermal Processes of Initiation  

Microsoft Academic Search

The sensitiveness of initiators to mechanical action has been examined in relation to heat, for lead azide, mercury fulminate, and in some cases lead styphnate, in order to see how far mechanical action could be equated with local heating. Previous information on mechanical sensitiveness has been extended by measuring friction sensitiveness with grit of varying hardness, and by varying the

A. R. Ubbelohde

1948-01-01

219

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

PubMed Central

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

Badyaev, Alexander V.; Uller, Tobias

2009-01-01

220

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

PubMed

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

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

2012-08-01

221

Mechanical properties of laser processed diamond-like carbon films  

SciTech Connect

Diamond-like carbon (DLC) films have a unique combination of physical and chemical properties such as high hardness, optical transparency, low coefficient of friction and chemical inertness. A pulsed laser (248 nm) has been used to ablate a pyrolytic graphite target to deposit DLC films on Si (100) and 7059 Corning glass substrates. The deposition was carried out in high vacuum ({le} 10{sup {minus}6} Torr) at different temperatures ranging from room temperature to 400 C. The films were characterized by x-ray diffraction, scanning electron microscope, and Raman spectroscopic techniques. The mechanical properties (hardness and Young`s modulus) of these films were characterized by nanoindentation. The authors have found that the films deposited at room temperature and 100 C show the characteristic features of DLC films and have the better hardness and modulus properties compared to the films fabricated at higher temperatures, which transform into amorphous carbon. Correlations of pulsed laser deposition process parameters with the properties of deposited DLC films will be discussed in this paper.

Kumar, A.; Ekanayake, U.; Shu, N.; Kjendal, D.; Wattuhewa, G. [Univ. of South Alabama, Mobile, AL (United States). Dept. of Electrical Engineering; Barnard, J.A. [Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Metallurgical and Materials Engineering; Vohra, Y. [Univ. of Alabama, Birmingham, AL (United States). Dept. of Physics

1996-12-31

222

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

223

Steam Trap Application  

E-print Network

The effective application of steam traps encompasses three primary areas which are the selection and sizing, the installation, and the monitoring of the steam trapping system. Proper application of steam traps will improve production rates, product...

Murphy, J. J.

1982-01-01

224

Trapping ions in a segmented ring trap  

NASA Astrophysics Data System (ADS)

We demonstrate robust trapping in an ion trap which has a ring shaped RF node. Ions are back-side loaded through a small 10 ?m diameter loading hole and we have demonstrated thousands of complete circuits around the trap. Each circuit passes through 44 trapping zones; the trap has 89 independent DC control electrodes. Measurements of the tangential secular frequency indicate a weak dependence on the RF and the loading hole. The ion trap is fabricated using four metal layers, allowing for the inner islanded electrodes to be electrically routed underneath the trap with negligible effects on the trapped ions. [4pt] This work was supported by the Intelligence Advanced Research Projects Activity (IARPA). Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

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

2012-06-01

225

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

SciTech Connect

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

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

1985-05-01

226

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

PubMed Central

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

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

2012-01-01

227

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

228

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,

229

CARRIER TRANSPORT AND TRAPPING PROCESS IN HIGH-RESISTIVITY CdTe GROWN BY A MODIFIED THM  

E-print Network

and detrapping processes in high-resistivity p-type crystals grown by a travelling heater method whichTe single crystals [5, 6] grown by a travelling heater method using a controlled Cd over- pressure. Injection of carriers in the time-of-flight method is achieved by a short pulse of a N2 laser. It appears

Paris-Sud XI, Université de

230

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

E-print Network

of superconductors which are promising materials for the permanent magnet applications [1-5]. Single domain bulk melt-processed RE­Ba­Cu­O has a large potential for use in permanent-magnet like engineering applications, the maximum value of remnant magnetic induction in a permanent magnet is about 1.5 Tesla for Nd

Boyer, Edmond

231

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

SciTech Connect

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

Knox, P.R. (Unocal, Santa Fe Springs, CA (USA))

1989-09-01

232

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

233

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

234

Copper ion-exchanged channel waveguides optimization for optical trapping.  

PubMed

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

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

2013-08-01

235

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

236

Understanding the mechanism of social network in the knowledge transfer process  

Microsoft Academic Search

Social network as a knowledge transfer mechanism is widely accepted. However, the process of the mechanism is vague. The goal of this study is to clearly expatiate on the functioning mechanism of social network during the process of knowledge transfer. We develop a model of social network which consists of the nodes and ties. The nodes in the knowledge social

Bing Wang; Jiting Yang; Hongpei Liu

2010-01-01

237

A Study of Optimality Theory and the Human Sentence Processing Mechanism  

Microsoft Academic Search

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

Rajvinder Singh

2002-01-01

238

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

239

The trapped region  

E-print Network

I will discuss some recent results on marginally outer trapped surfaces, apparent horizons, and the trapped region. A couple of applications of the results developed for marginally outer trapped surfaces to coalescence of black holes and to the characterization of the trapped region are given.

Lars Andersson

2009-01-17

240

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

SciTech Connect

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

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

1998-05-01

241

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

242

Trap-Assisted Gas Sensing Mechanism in Pd\\/TiO2\\/SiO2\\/SiC Capacitors at High Temperatures  

Microsoft Academic Search

We demonstrate that the gas concentration in a high-temperature environment can be measured using the leakage current through a dielectric stack on silicon carbide, comprising silicon dioxide and titanium dioxide. The variation in the leakage current may be explained by the trap-assisted conduction model, where the barrier height is observed to be dependent on the concentration of gas. The behavior

Ming-Hung Weng; Rajat Mahapatra; Alton B. Horsfall; Nicholas G. Wright

2007-01-01

243

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

244

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

245

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

246

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

247

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

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

2014-07-01

248

Ion Trap Mass Spectrometry  

SciTech Connect

This chapter describes research conducted in a few research groups in the 1990s in which RF quadrupole ion trap mass spectrometers were coupled to a powerful atomic ion source, the inductively coupled plasma used in conventional ICP-MS instruments. Major section titles for this chapter are: RF Quadrupole Ion Traps Features of RF Quadrupole Ion Trap Mass Spectrometers Selective Ion Trapping methods Inductively Coupled Plasma Source Ion Trap Mass Spectrometers

Eiden, Greg C.

2005-09-01

249

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...

250

Processing mechanics of alternate twist ply (ATP) yarn technology  

Microsoft Academic Search

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

Donia Said Elkhamy

2007-01-01

251

Experimental Studies on Mechanism of Material Removal in Abrasive Flow Machining Process  

Microsoft Academic Search

In this article, the mechanism of material removal (MR) in Abrasive Flow Machining (AFM) process has been studied. Representative components of pure Aluminum and Brass were processed by AFM under similar process conditions. The processed surfaces were analyzed with the help of Scanning Electron Microscopy (SEM). SEM photographs reveal noticeable difference between abrasion patterns produced on the processed surfaces of

Sehijpal Singh; H. S. Shan; Pradeep Kumar

2008-01-01

252

OPTIMIZATION OF METAL FORMING PROCESSES FOR IMPROVING FINAL MECHANICAL STRENGTH  

E-print Network

. The practical optimization is carried out by a genetic algorithm technique or by a surface response method. Abstract. The fundamental mechanical assumptions and the basic principles of 3-dimensional FE. Fundamentals and Applications COMPLAS XI E. Oñate, D.R.J. Owen, D. Peric and B. Suárez (Eds) hal-00675507

Paris-Sud XI, Université de

253

Graduate Students Associated with the Materials and Process Mechanics Laboratory  

E-print Network

Mechanics of Blast Cleaning as Applied to Gas-Turbine Rotor Deposits 2000 M.A.Sc. I. Farid Viscoelastic. Cottrell The Influence of Surface Properties on Zebra Mussel Adhesion (co-supervisor D.G. Allen) 2000 M Polytechnic Univ.) 2002 M.A.Sc. D. Ciampini Computer Simulation of Interference Effects in Particle Streams

254

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

255

Collimation processes in quantum mechanics interpreted in quantum real numbers  

Microsoft Academic Search

We reexamine the theory of quantum mechanics using non-standard real numbers, called quantum real numbers (qr-numbers), that are constructed from entities in the standard Hilbert space formulation of the theory. Our motivation is to elucidate certain apparently paradoxical features of the standard theory by enlarging the class of real numbers that physical quantities can take as numerical values. The concept

John Vincent Corbett; Thomas Durt

2009-01-01

256

PROCESS SYSTEMS ENGINEERING Design of Flexible Reduced Kinetic Mechanisms  

E-print Network

and Marianthi G. Ierapetritou Dept. of Chemical and Biochemical Engineering, Rutgers, The State University successful if it matches the predictions of laminar flame speed, adiabatic temperature rise, auto ignition, the reduced mechanism can be directly incorpo- rated into the chemical source terms of a reactor model hav

Androulakis, Ioannis (Yannis)

257

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

258

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

259

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

NASA Astrophysics Data System (ADS)

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

Midya, Kousik; Dhar, Subhabrata; Kottantharayil, Anil

2013-10-01

260

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.

261

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

262

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

263

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

264

Structures, Processes and Relational Mechanisms for IT Governance  

Microsoft Academic Search

In many organisations, Information Technology (IT) has become crucial in the support, the sustainability and the growth of the business. This pervasive use of technology has created a critical dependency on IT that calls for a specific focus on IT Governance. IT Governance consists of the leadership and organisational structures and processes that ensure that the organisation's IT sustains and

Wim Van Grembergen; Steven De Haes

265

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

266

Mechanism of the Primary Photodissociation Processes of Organic Molecules  

Microsoft Academic Search

Two rules have been derived experimentally from investigations of the continuous absorption spectra of inorganic molecules1. First, the action of light may produce the splitting of a single bond, the two products of dissociation, namely, atoms or radicals, possessing free valencies. This process occurs as long as the central atom of the original molecule is in a lower state of

Ernst Bergmann; R. Samuel

1938-01-01

267

Natural mechanisms protecting against cancer  

Microsoft Academic Search

Carcinogenesis is a multistage process. At each step of this process, there are natural mechanisms protecting against development of cancer. The majority of cancers in humans is induced by carcinogenic factors present in our environment including our food. However, some natural substances present in our diet or synthesized in our cells are able to block, trap or decompose reactive oxygen

Marek Jakbisiak; Witold Lasek; Jakub Go?

2003-01-01

268

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

269

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

270

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.

2000-07-11

271

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

272

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

E-print Network

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

Wei, Qiuming

273

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

274

Mechanism of silk processing in insects and spiders  

NASA Astrophysics Data System (ADS)

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

Jin, Hyoung-Joon; Kaplan, David L.

2003-08-01

275

Steam Trap Users' Guide.  

National Technical Information Service (NTIS)

Steam traps are an important element in the efficient operation of a steam system and in energy conservation. The high cost of producing and delivering steam mandates an effective steam trap inspection and maintenance program at all applicable naval activ...

D. M. Sneed, J. C. King

1985-01-01

276

HP Steam Trap Monitoring  

E-print Network

STEAM MONITORING HP Steam Trap Monitoring HP Steam Trap Monitoring ? 12-18 months payback! ? 3-5% permanent reduction in consumption ? LEED Pt.? Innovation in Operations EB O&M ? Saved clients over $1,000,000 Annual consumption... 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

277

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

278

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

279

Sorption vacuum trap  

NASA Technical Reports Server (NTRS)

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

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

1970-01-01

280

Computational mechanisms of mechanosensory processing in the cricket.  

PubMed

Crickets and many other orthopteran insects face the challenge of gathering sensory information from the environment from a set of multi-modal sensory organs and transforming these stimuli into patterns of neural activity that can encode behaviorally relevant stimuli. The cercal mechanosensory system transduces low frequency air movements near the animal's body and is involved in many behaviors including escape from predators, orientation with respect to gravity, flight steering, aggression and mating behaviors. Three populations of neurons are sensitive to both the direction and dynamics of air currents: an array of mechanoreceptor-coupled sensory neurons, identified local interneurons and identified projection interneurons. The sensory neurons form a functional map of air current direction within the central nervous system that represents the direction of air currents as three-dimensional spatio-temporal activity patterns. These dynamic activity patterns provide excitatory input to interneurons whose sensitivity and spiking output depend on the location of the neuronal arbors within the sensory map and the biophysical and electronic properties of the cell structure. Sets of bilaterally symmetric interneurons can encode the direction of an air current stimulus by their ensemble activity patterns, functioning much like a Cartesian coordinate system. These interneurons are capable of responding to specific dynamic stimuli with precise temporal patterns of action potentials that may encode these stimuli using temporal encoding schemes. Thus, a relatively simple mechanosensory system employs a variety of complex computational mechanisms to provide the animal with relevant information about its environment. PMID:18490398

Jacobs, Gwen A; Miller, John P; Aldworth, Zane

2008-06-01

281

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

282

A proposal for continuous loading of an optical dipole trap with magnetically guided ultra cold atoms  

E-print Network

The capture of a moving atom by a non-dissipative trap, such as an optical dipole trap, requires the removal of the excessive kinetic energy of the atom. In this article we develop a mechanism to harvest ultra cold atoms from a guided atom beam into an optical dipole trap by removing their directed kinetic energy. We propose a continuous loading scheme where this is accomplished via deceleration by a magnetic potential barrier followed by optical pumping to the energetically lowest Zeeman sublevel. We theoretically investigate the application of this scheme to the transfer of ultra cold chromium atoms from a magnetically guided atom beam into a deep optical dipole trap. We discuss the realization of a suitable magnetic field configuration. Based on numerical simulations of the loading process we analyze the feasibility and efficiency of our loading scheme.

Anoush Aghajani-Talesh; Markus Falkenau; Axel Griesmaier; Tilman Pfau

2009-12-11

283

Microstructural banding in thermally and mechanically processed titanium 6242  

NASA Astrophysics Data System (ADS)

Ti-6Al-2Sn-4Zr-2Mo-0.1Si coupons were shaped by repeated cycles of heating (to 954 ) and hammer or press forging followed by a solution anneal that varied from 968 to 998 . The coupons were originally extracted from billets forged below the beta transus (1009 ) and slow cooled to ambient temperatures. Macroscopic and microstructural banding is observed in some forged and solution annealed coupons. The microstructure consists of elongated platelets of primary alpha. More significant banding is observed subsequent to annealing at lower temperatures (968 ), whereas subsequent to higher annealing temperatures (998 ) much less microstructural banding is present. About the same level of banding is observed in hammer forged coupons and press forged coupons. The observation of these bands is significant, because these may lead to inhomogeneous mechanical properties. Specifically, some types of banding are reported to affect the high-temperature creep properties of this alloy. Classically, banding in Ti6242-0.1Si has been regarded as a result of adiabatic shear, chill zone formation, or compositional in homogeneity. High- and low-magnification metallography, electron microprobe analysis, and micro-hardness tests were performed on forged and annealed specimens in this investigation. The bands of this study appear to originate from the microstructure that consists of the forged billet of elongated primary alpha. The deformation of the extracted coupon is neither fully homogeneous nor sufficiently substantial, and the coupon is only partly statically restored after a solution anneal. Areas not fully restored appear as bands with elongated primary alpha that are remnant of the starting billet microstructure. Therefore, a source of banding in Ti- 6242- O.1Si alloy additional to the classic sources is evident. This type of banding is likely removed by relatively high solution treatment temperatures and perhaps greater plastic deformation during forging.

Kansal, U.; Kassner, M. E.; Hiatt, D. R.; Bristow, B. M.

1992-06-01

284

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

285

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

286

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

SciTech Connect

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

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

2013-05-15

287

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

2010-10-28

288

Dissociable Brain Mechanisms for Processing Social Exclusion and Rule Violation  

PubMed Central

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

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

2010-01-01

289

Comparison of energy consumptions between ultrasonic, mechanical, and combined soil washing processes.  

PubMed

Vigorous physical effects including micro-jet and micro-streaming can be induced in heterogeneous systems by acoustic cavitation. This can be useful for the removal of pollutants from contaminated soil particles. In this study, the diesel removal efficiencies in ultrasonic, mechanical, and combined soil washing processes have been compared considering the electrical energy consumptions for these processes. The combined process showed synergistic effects for both removal efficiency and effective volume also has the advantage of a short operation time compared to the sequential processes. Thus the ultrasonic soil washing process with mechanical mixing is considered a promising technology for industrial use. PMID:22153227

Son, Younggyu; Nam, Sanggeon; Ashokkumar, Muthupandian; Khim, Jeehyeong

2012-05-01

290

A Laplace pressure based microfluidic trap for passive droplet trapping and controlled release  

PubMed Central

Here, we present a microfluidic droplet trap that takes advantage of the net Laplace pressure force generated when a droplet is differentially constricted. Mathematical simulations were first used to understand the working range of the component; followed by finite element modeling using the CFD software package to further characterize the behavior of the system. Controlled release of the trapped droplets is also demonstrated through both a mechanical method and a chemical method that manipulates the total pressure exerted on the trapped droplet. The unique design of this trapping device also provides the capability for selection of a single droplet from a train, as well as droplet fusion. PMID:22662095

Simon, Melinda G.; Lin, Robert; Fisher, Jeffrey S.; Lee, Abraham P.

2012-01-01

291

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.

292

Changing the branching mechanism of a continuous state branching process using immigration  

Microsoft Academic Search

We consider an initial population whose size evolves according to a continu- ous state branching process. Then we add to this process an immigration (with the same branching mechanism as the initial population), in such a way that the immigration rate is proportional to the whole population size. We prove this continuous state branching process with immigration proportional to its

Romain Abraham; JEAN-FRANCOIS DELMAS

2006-01-01

293

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

E-print Network

, and their performance is limited primarily by their tensile strength. Consequently, sample reinforcement is the key to performance improvement in these technologically important materials. In this work, we report a trapped ?eld of 17.6 T, the largest reported to date...

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

294

The photonic light trapImproved light trapping in solar cells by angularly selective filters  

Microsoft Academic Search

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

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

2009-01-01

295

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

296

Comparison of Continuous SPD Processes for Improving the Mechanical Properties of Aluminum Alloy 6111.  

National Technical Information Service (NTIS)

Microstructure evolution, mechanical properties, formability, and texture development were determined for AA6111 samples processed by asymmetric rolling (ASR) with different roll friction, velocity, or diameters, conventional rolling (CR), and equal-chann...

L. S. Toth, M. Winkler, R. Lapovok, S. L. Semiatin

2008-01-01

297

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

E-print Network

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

Gbondo-Tugbawa, Tamba Edward

2002-01-01

298

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 the chemical content of the reactant mixture to include addi- tional titanium. These cermets combine the high

Meyers, Marc A.

299

Thermoeconomic design of a multi-effect evaporation mechanical vapor compression (MEEMVC) desalination process  

Microsoft Academic Search

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

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

2008-01-01

300

Analysis of mechanical error in a fused deposition process using a stochastic approach  

Microsoft Academic Search

A stochastic model has been developed for studying the mechanical error in different rapid prototyping (RP) processes. Tolerances and clearances, which cause mechanical error, have been assumed to be random variables. The coordinates of a point on the work surface traced by the laser beam or the tip of the extruder head is expressed as a function of the random

Sanat Agrawal; S. G. Dhande

2007-01-01

301

Mechanical, thermal and physical coupling methods in FE analysis of metal forming processes  

Microsoft Academic Search

The thermal and mechanical equations for large deformations occuring in metal forming processes are recalled. The finite element approaches for viscoplastic or for elastic viscoplastic materials are presented briefly. The coupling of the previous equations with those describing the evolution of physical internal parameters is analysed. A compact form of the physical and mechanical equation is used to consider any

J.-L. Chenot; Y. Chastel

1996-01-01

302

Cohesive and frictional strengthening of fault zones by chemical and mechanical processes  

Microsoft Academic Search

Fault-zones in saw-cut experiments may display significant strengthening when subjected to long periods of holding. Two groups of mechanisms control the strengthening: (1) chemical processes (pressure solution, Ostwald's ripening, grain growth, crack and void filling) that are more effective under long-term, hot and water-saturated conditions, and (2) mechanical processes (grain crushing, compaction, plastic flow) that are more effective under short-term,

Z. Reches; T. A. Dewers

2002-01-01

303

Thermalhydrologicmechanicalchemical processes in the evolution of engineered geothermal reservoirs  

Microsoft Academic Search

In a companion paper [Taron J, Elsworth D, Min K-B. Numerical simulation of thermalhydrologicmechanicalchemical processes in deformable, fractured porous media. Int J Rock Mech Min Sci 2009; doi:10.1016\\/j.ijrmms.2009.01.008] we introduced a new methodology and numerical simulator for the modeling of thermalhydrologicmechanicalchemical processes in dual-porosity media. In this paper we utilize the model to examine some of the dominant behaviors and

Joshua Taron; Derek Elsworth

2009-01-01

304

The effect of process conditions on mechanical properties of laser-sintered nylon  

Microsoft Academic Search

Purpose The purpose of this paper is to measure the effect of process conditions on mechanical properties of laser-sintered nylon 12 (Duraform) and to determine the range of conditions that provide consistent mechanical performance for additive manufacturing. Design\\/methodology\\/approach Tensile test specimens were fabricated over a range of well-characterized process conditions including laser power, laser speed, scan spacing, layer

Thomas L. Starr; Timothy J. Gornet; John S. Usher

2011-01-01

305

Microparticle trapping in an ultrasonic Bessel beam  

PubMed Central

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

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

2011-01-01

306

Environmental trace analysis by ion trap mass spectrometry  

SciTech Connect

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

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

1995-12-31

307

Coherent Manipulation of Holes in Dipole Trap Arrays  

E-print Network

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

Benseny, Albert; Bagud, Joan; Corbaln, Ramn; Picn, Antonio; Roso, Luis; Birkl, Gerhard; Mompart, Jordi

2009-01-01

308

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

309

Neutral atom traps.  

SciTech Connect

This report describes progress in designing a neutral atom trap capable of trapping sub millikelvin atom in a magnetic trap and shuttling the atoms across the atom chip from a collection area to an optical cavity. The numerical simulation and atom chip design are discussed. Also, discussed are preliminary calculations of quantum noise sources in Kerr nonlinear optics measurements based on electromagnetically induced transparency. These types of measurements may be important for quantum nondemolition measurements at the few photon limit.

Pack, Michael Vern

2008-12-01

310

Micro-fabricated stylus ion trap.  

PubMed

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, (25)Mg(+) 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 ( = 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. PMID:24007096

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

311

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

312

Evaluating Steam Trap Performance  

E-print Network

The variables are listed below, algebraic symools. used along in the economic with their unit an~lysis and Variable No. Symbol Description 1 2 3 P T P RK HI price of trap, dollars price of repair kit, doll time required to install rs trap... The variables are listed below, algebraic symools. used along in the economic with their unit an~lysis and Variable No. Symbol Description 1 2 3 P T P RK HI price of trap, dollars price of repair kit, doll time required to install rs trap...

Fuller, N. Y.

313

Trapped Electron Lifetimes in the Inner Magnetosphere  

NASA Astrophysics Data System (ADS)

Some geomagnetic storms increase the trapped electron intensity in the slot and inner radiation belt. Man- made events such as the high-altitude nuclear tests of the late 1960's also were found to inject new and intense populations of electrons in the inner magnetosphere. In both cases, spacecraft measurements of the change in the trapped electron intensity observed in low-Earth orbit or at higher altitudes have been clues to the loss processes at work. The nuclear tests provided a known injection time and showed that the typical lifetime for ~0.5 MeV electrons was peaked at about 1 year inside an L-shell of ~1.6 and dropped to only a few days outside L~2. Pitch-angle scattering by VLF transmitter waves is sufficiently strong to be the dominant source for the change in the lifetime at the outer edge of the inner radiation belt. In this paper we revisit the determination of the L-shell dependence of electron lifetime using recent measurements from low-Earth orbit and higher altitudes. In particular, long-baseline measurements from missions such as NASA/SAMPEX and NOAA/POES allow for the determination of decay rates versus L in many intense electron injections. We will compare these recent measurements with those made in the past and with models that include multiple scattering mechanisms. This work was supported under The Aerospace Corporation's Independent Research and Development Program.

Mazur, J. E.

2006-05-01

314

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

E-print Network

Precipitation and mechanical properties of supersaturated Al-Zn-Mg alloys processed by severe the precipitation process and consequently has a strong influence on the strength of these alloys. Introduction density, precipitation. Abstract. Supersaturated Al-4.8Zn-1.2Mg-0.14Zr and Al-5.7Zn-1.9Mg-0.35Cu (wt

Gubicza, Jenõ

315

Microstructure and mechanical properties of SiC particle reinforced magnesium composites processed by injection molding  

Microsoft Academic Search

The microstructure and the mechanical properties of AZ91 and AJ62 reinforced with SiC particles processed by magnesium injection molding were investigated. As a starting point, melt stirring experiments were carried out on a small laboratory scale. In both processes, injection molding and melt stirring, the particles were found to be distributed homogeneously within in the matrix. Reactions between matrix and

C. Rauber; A. Lohmller; S. Opel; R. F. Singer

2011-01-01

316

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

Microsoft Academic Search

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 possibility, we assessed decrease in differential activation during the second presentation of

Motoaki Sugiura; Yoko Mano; Akihiro Sasaki; Norihiro Sadato

2011-01-01

317

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

318

Microstructures and mechanical properties of Ti5553 alloy processed by high-pressure torsion  

NASA Astrophysics Data System (ADS)

In the present research, the effects of high-pressure torsion (HPT) processing on the microstructure and mechanical properties of Ti-5Al-5Mo-5V-3Cr (Ti5553) alloy were studied. HPT processing produced a white etching layer (WEL) in the middle section of the cross-section and numerous shear bands in the surface region of the cross-section. And the thickness of the WEL increased with increasing the HPT revolutions. TEM observation of the WEL revealed an ultrafine-grained structure with high degree of lattice distortions. The mechanical properties measurements showed that the hardness and ultimate tensile strength increased by HPT processing, accompanied with a decrease in the elongation to failure. It is considered that the mechanical properties of HPT processed Ti5553 alloy are mostly dominated by the shear banded region and the WEL where have the finest grain size and high density of dislocations.

Jiang, B. Z.; Emura, S.; Tsuchiya, K.

2014-08-01

319

Formation mechanisms of laboratory double layers  

NASA Technical Reports Server (NTRS)

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

Chan, Chung

1987-01-01

320

Vertically averaged approaches for CO2 migration with solubility trapping  

NASA Astrophysics Data System (ADS)

The long-term storage security of injected carbon dioxide (CO2) is an essential component of geological carbon sequestration operations. In the postinjection phase, the mobile CO2 plume migrates in large part because of buoyancy forces, following the natural topography of the geological formation. The primary trapping mechanisms are capillary and solubility trapping, which evolve over hundreds to thousands of years and can immobilize a significant portion of the mobile CO2 plume. However, both the migration and trapping processes are inherently complex, spanning multiple spatial and temporal scales. Using an appropriate model that can capture both large- and small-scale effects is essential for understanding the role of these processes on the long-term storage security of CO2 sequestration operations. Traditional numerical models quickly become prohibitively expensive for the type of large-scale, long-term modeling that is necessary for characterizing the migration and immobilization of CO2 during the postinjection period. We present an alternative modeling option that combines vertically integrated governing equations with an upscaled representation of the dissolution-convection process. With this approach, we demonstrate the effect of different modeling choices for typical large-scale geological systems and show that practical calculations can be performed at the temporal and spatial scales of interest.

Gasda, S. E.; Nordbotten, J. M.; Celia, M. A.

2011-05-01

321

Trap diversity and evolution in the family Droseraceae  

PubMed Central

We review trapping mechanisms in the carnivorous flowering plant family Droseraceae (order Caryophyllales). Its members are generally known to attract, capture, retain and digest prey animals (mainly arthropods) with active snap-traps (Aldrovanda, Dionaea) or with active sticky flypaper traps (Drosera) and to absorb the resulting nutrients. Recent investigations revealed how the snap-traps of Aldrovanda vesiculosa (waterwheel plant) and Dionaea muscipula (Venus flytrap) work mechanically and how these apparently similar devices differ as to their functional morphology and shutting mechanics. The Sundews (Drosera spp.) are generally known to possess leaves covered with glue-tentacles that both can bend toward and around stuck prey. Recently, it was shown that there exists in this genus a higher diversity of different tentacle types and trap configurations than previously known which presumably reflect adaptations to different prey spectra. Based on these recent findings, we finally comment on possible ways for intrafamiliar trap evolution. PMID:23603942

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

2013-01-01

322

Trap diversity and evolution in the family Droseraceae.  

PubMed

We review trapping mechanisms in the carnivorous flowering plant family Droseraceae (order Caryophyllales). Its members are generally known to attract, capture, retain and digest prey animals (mainly arthropods) with active snap-traps (Aldrovanda, Dionaea) or with active sticky flypaper traps (Drosera) and to absorb the resulting nutrients. Recent investigations revealed how the snap-traps of Aldrovanda vesiculosa (waterwheel plant) and Dionaea muscipula (Venus' flytrap) work mechanically and how these apparently similar devices differ as to their functional morphology and shutting mechanics. The Sundews (Drosera spp.) are generally known to possess leaves covered with glue-tentacles that both can bend toward and around stuck prey. Recently, it was shown that there exists in this genus a higher diversity of different tentacle types and trap configurations than previously known which presumably reflect adaptations to different prey spectra. Based on these recent findings, we finally comment on possible ways for intrafamiliar trap evolution. PMID:23603942

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

2013-07-01

323

Microkinetic modeling of lean NOx trap chemistry  

SciTech Connect

A microkinetic chemical reaction mechanism capable of describing both the storage and regeneration processes in a fully formulated lean NO{sub x} trap is presented. The mechanism includes steps occurring on the precious metal, NO{sub x} storage, and oxygen storage sites of the catalyst. The complete reaction set is used with a transient plug flow reactor code (including boundary layer mass transfer) to simulate not only storage/regeneration cycles with a CO/H{sub 2} reductant, but also steady flow temperature sweep experiments that were previously analyzed with just a precious metal mechanism and a simpler steady state code. The results imply that NO{sub x} storage was not negligible during some of the temperature ramps, necessitating a re-evaluation of the precious metal kinetic parameters. The parameters for the entire mechanism are inferred by finding the best overall fit to the complete set of experiments. Rigorous thermodynamic consistency is enforced for parallel reaction pathways and with respect to known data for all gas phase species. It is found that nearly all of the basic experimental observations can be reproduced with the transient simulations.

Larson, Rich [Sandia National Laboratories (SNL); Chakravathy, Kalyana [Oak Ridge National Laboratory (ORNL); Pihl, Josh A [ORNL; Daw, C Stuart [ORNL

2012-01-01

324

Exploring the effect of interfacial tension, viscosity, and flow rate on the effectiveness of capillary trapping of CO2  

NASA Astrophysics Data System (ADS)

Typical geologic carbon sequestration scenarios involve the injection of supercritical CO2 into an aquifer while displacing brine in what is equivalent to a water drainage process. Due to density differences, the CO2 will tend to buoyantly migrate upward until an impermeable barrier is encountered. This buoyant CO2 plume may persist for hundreds to thousands of years posing a challenge to ensuring the long-term integrity of CO2 storage. However, a potentially large fraction of the CO2 may be immobilized by one of several trapping mechanisms. Once injection stops, buoyant forces will continue to propel the supercritical CO2 upwards, while brine reoccupies the pore space in a water imbibition process, resulting in capillary trapping of some of the CO2. In addition, supercritical CO2 is partially miscible in brine and will dissolve in the brine forming a negatively buoyant phase (dissolution trapping), and will subsequently dissolve minerals to form bicarbonate and carbonate ions (ionic trapping) and may ultimately precipitate as mineral carbonates (mineral trapping). In the capillary trapping process, supercritical CO2 is immobilized by the imbibition process where capillary interactions lock isolated CO2 bubbles within unconnected rock pore space. These bubbles have significantly increased surface area with respect to brine and rock compared to bulk storage, and may facilitate enhanced dissolution of gaseous CO2 into the brine as well as chemical reactions. Thus, one approach to demonstrating storage security is the quantification of the rate and extent of these trapping mechanisms. We present experimental results based on computed x-ray microtomography (CMT) for quantifying capillary trapping mechanisms as a function of fluid properties using several pairs of analog fluids to span a range of potential supercritical CO2-brine conditions. Our experiments are conducted in a core-flood apparatus using synthetic porous media and we investigate capillary trapping by measuring trapped non-wetting phase area as a function of varying interfacial tension, viscosity, and wetting flow rate. Experiments are repeated for a single sintered glass bead core using three different non-wetting phase fluids and varying concentrations of surfactants to explore and separate the effects of interfacial tension, viscosity, and fluid flow rate. Analysis of the data demonstrates distinct and consistent differences in the amount of initial (i.e. following CO2 injection) and residual (i.e. following flood or WAG scheme) nonwetting phase occupancy as a function of fluid properties and flow rate. Further experimentation and analyses is needed, but these preliminary results indicate trends that can guide design of injection scenarios such that both initial and residual trapped gas occupancy is optimized.

Wildenschild, D.; Herring, A. L.; Carey, J. W.; Young, I. M.

2010-12-01

325

Buffer strips trap contaminants  

E-print Network

ater Buffer strips trap contaminants Three research and demonstration projects seek to determine ideal width for riparian buffer strips in Midwest. They trap sediment, nutrients and pesticides. That ma kes riparian buffer strips a valuable tool in preventing nonpo int sour ce pollution, according

Nebraska-Lincoln, University of

326

Steam Trap Monitor.  

National Technical Information Service (NTIS)

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...

M. J. Ryan

1987-01-01

327

Optical trapping of nanoparticles.  

PubMed

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

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

2013-01-01

328

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

329

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

PubMed

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

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

2012-09-01

330

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

331

Diesel Engine Condition Classification Based on Mechanical Dynamics and Time-Frequency Image Processing  

Microsoft Academic Search

\\u000a In this research, mechanical structure dynamics for diesel engine working process are investigated in detail for diesel engine\\u000a vibration signal analysis and pattern recognition. Time domain vibration signal can be looked on as several impulse forces\\u000a responses according to mechanical dynamics analysis. Different part vibration signal can be used for different components\\u000a fault diagnoses. It is very useful to determine

Hongkun Li; Zhixin Zhang

332

Numerical simulation of thermal-hydrologic-mechanical-chemical processes in deformable, fractured porous media  

Microsoft Academic Search

A method is introduced to couple the thermal (T), hydrologic (H), and chemical precipitation\\/dissolution (C) capabilities of TOUGHREACT with the mechanical (M) framework of FLAC3D to examine THMC processes in deformable, fractured porous media. The combined influence of stress-driven asperity dissolution, thermal-hydro-mechanical asperity compaction\\/dilation, and mineral precipitation\\/dissolution alter the permeability of fractures during thermal, hydraulic, and chemical stimulation. Fracture and

Joshua Taron; Derek Elsworth; Ki-Bok Min

2009-01-01

333

Surface trap for ytterbium ions  

E-print Network

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

Campbell, Jonathan A. (Jonathan Alan)

2006-01-01

334

Focused plasmonic trapping of metallic particles  

PubMed Central

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

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

2013-01-01

335

Atom trap loss, elastic collisions, and technology  

NASA Astrophysics Data System (ADS)

The study of collisions and scattering has been one of the most productive approaches for modern physics, illuminating the fundamental structure of crystals, surfaces, atoms, and sub-atomic particles. In the field of cold atoms, this is no less true: studies of cold atom collisions were essential to the production of quantum degenerate matter, the formation of cold molecules, and so on. Over the past few years it has been my delight to investigate elastic collisions between cold atoms trapped in either a magneto-optical trap (MOT) or a magnetic trap with hot, background gas in the vacuum environment through the measurement of the loss of atoms from the trap. Motivated by the goal of creating cold atom-based technology, we are deciphering what the trapped atoms are communicating about their environment through the observed loss rate. These measurements have the advantages of being straightforward to implement and they provide information about the underlying, fundamental inter-atomic processes. In this talk I will present some of our recent work, including the observation of the trap depth dependence on loss rate for argon-rubidium collisions. The data follow the computed loss rate curve based on the long-range Van der Waals interaction between the two species. The implications of these findings are exciting: trap depths can be determined from the trap loss measurement under controlled background density conditions; observation of trap loss rate in comparison to models for elastic, inelastic, and chemical processes can lead to improved understanding and characterization of these fundamental interactions; finally the marriage of cold atoms with collision modeling offers the promise of creating a novel pressure sensor and pressure standard for the high and ultra-high vacuum regime.

Booth, James

2012-10-01

336

Numerical Prediction of Microstructure and Mechanical Properties During the Hot Stamping Process  

NASA Astrophysics Data System (ADS)

Numerical simulation and prediction of microstructures and mechanical properties of products is very important in product development of hot stamping parts. With this method we can easily design changes of hot stamping products' properties prior to the manufacturing stage and this offers noticeable time and cost savings. In the present work, the hot stamping process of a U-channel with 22MnB5 boron steels is simulated by using a coupled thermo-mechanical FEM program. Then with the temperature evolution results obtained from the simulation, a model is applied to predict the microstructure evolution during the hot stamping process and mechanical properties of this U-channel. The model consists of a phase transformation model and a mechanical properties prediction model. The phase transformation model which is proposed by Li et al is used to predict the austenite decomposition into ferrite, pearlite, and bainite during the cooling process. The diffusionless austenite-martensite transformation is modeled using the Koistinen and Marburger relation. The mechanical properties prediction model is applied to predict the products' hardness distribution. The numerical simulation is evaluated by comparing simulation results with the U-channel hot stamping experiment. The numerically obtained temperature history is basically in agreement with corresponding experimental observation. The evaluation indicates the feasibility of this set of methods to be used to guide the optimization of hot stamping process parameters and the design of hot stamping tools.

Kan, Dongbin; Liu, Lizhong; Hu, Ping; Ma, Ning; Shen, Guozhe; Han, Xiaoqiang; Ying, Liang

2011-08-01

337

Thermomechanical processing and mechanical properties of hypereutectoid steels and cast irons  

SciTech Connect

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

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

1998-01-01

338

Fabrication of fine recrystallized grains and their mechanical property in HPT processed pure magnesium  

NASA Astrophysics Data System (ADS)

To clarify the grain size effect on mechanical property in fine grained pure Mg, mechanical properties of fully recrystallized Mg with fine grain sizes were investigated. The specimens having fully recrystallized microstructures with mean grain sizes of 2.8 ?m and 7.8 ?m were fabricated by HPT processing and subsequent annealing. The 2.8 ?m specimen showed discontinuous yielding with a high yield stress and low strain hardening while the 7.8 ?m specimen showed continuous yielding with a low yield stress and high strain hardening. The as-HPT processed specimen showed a larger ductility than that in the subsequently annealed specimens.

Joshi, Mohit; Fukuta, Yuko; Gao, Si; Park, Nokeun; Terada, Daisuke; Tsuji, Nobuhiro

2014-08-01

339

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

340

Use of Forced Mineral Trapping for Sequestration of CO2  

SciTech Connect

Reactive transport calculations of a sliding in situ precipitation (SLIP) concept were validated with a set of pressurized unsaturated flow (PUF) experiments. A counter-flow injection strategy was shown to be very effective in controlling the location of a calcite precipitation front and thus could be used to maximize utilization of reservoir capacity for permanent carbon sequestration via mineral trapping. Further work is needed to examine coupled feedback mechanisms on liquid and gas flow as the permeability and pore structure of the porous medium will change significantly during the process. Work is underway to extend the modeling and experiments to investigate 2-D flow and transport processes, which may respond differently than the present 1-D analysis would suggest. Although we have focused on the precipitation of calcite for forced mineral trapping, the technique may also work with other carbonate minerals. For example, injection of reducing stack gas impurities, such as SO{sub 2}, along with the CO{sub 2} could be used to reduce the oxidation states of transition metals and precipitate insoluble carbonates. Iron-rich minerals, such as glauconitic clay and hematite, contain iron predominantly in the ferric state. Reduction of iron to the ferrous state could help bind carbon in the form of ferrous carbonate (siderite). Another example is forming manganese carbonate (rhodochrosite) by the reduction of manganese from manganese bearing minerals in higher oxidation states. This electrochemical type of forced mineral trapping could be applied in formations rich in iron or manganese bearing minerals.

McGrail, B. Peter; Martin, Paul F.; Saripalli, K Prasad; Bryant, Steven L.; Sass, Bruce M.

2001-11-27

341

Random telegraph signal noise mechanisms in reverse base current of hot carrier-degraded submicron bipolar transistors: Effect of carrier trapping during stress on noise characteristics  

Microsoft Academic Search

We investigate physical mechanisms of random telegraph signal (RTS) noise in reverse base current of hot carrier-degraded polysilicon emitter bipolar junction transistors. RTS noise, analyzed in the time domain, is studied as a function of reverse base-emitter bias, temperature, and additional reverse-bias stress. Two-level RTS with a relative amplitude as high as 100% is observed at room temperature. The RTS

D. Pogany; J. A. Chroboczek; G. Ghibaudo

2001-01-01

342

Mechanical methods for dry particle coating processes and their applications in drug delivery and development.  

PubMed

Modification of the surface properties of particles, which is usually achieved by coating, is desirable to maintain and enhance the utility of these particles. Saving of time, energy, number of additives, process steps and consequently, the cost of the coating process leads to development of dry coating processes using mechanical methods which exclude any liquid solvent or binder solution and are environmentally safe, and cost-effective. Mechanofusion, hybridization, magnetic assisted impaction coating, theta-composer, rotating fluidized bed coating, pressure swing granulation and high shear mixing have been extensively patented and reported in the scientific literature. These mechanical methods have found multidisciplinary applications in drug development and drug delivery. Various devices available for the dry coating process, their principle, method of working, benefits and limitations along with various applications relevant to the pharmaceutical field are discussed in the current article. PMID:19939220

Gera, Manoj; Saharan, Vikas A; Kataria, Mahesh; Kukkar, Vipin

2010-01-01

343

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

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

344

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

NASA Astrophysics Data System (ADS)

The research reported in this dissertation investigates the processes required to mechanically alloy Pb1- xSnxTe and AgSbTe2 and a method of combining these two end compounds to result in (y)(AgSbTe 2)--(1 -- y)(Pb1- xSnxTe) thermoelectric materials for power generation applications. In general, traditional melt processing of these alloys has employed high purity materials that are subjected to time and energy intensive processes that result in highly functional material that is not easily reproducible. This research reports the development of mechanical alloying processes using commercially available 99.9% pure elemental powders in order to provide a basis for the economical production of highly functional thermoelectric materials. Though there have been reports of high and low ZT materials fabricated by both melt alloying and mechanical alloying, the processing-structure-properties-performance relationship connecting how the material is made to its resulting functionality is poorly understood. This is particularly true for mechanically alloyed material, motivating an effort to investigate bulk material within the (y)(AgSbTe 2)--(1 -- y)(Pb1- xSnx-Te) system using the mechanical alloying method. This research adds to the body of knowledge concerning the way in which mechanical alloying can be used to efficiently produce high ZT thermoelectric materials. The processes required to mechanically alloy elemental powders to form Pb1-xSnxTe and AgSbTe2 and to subsequently consolidate the alloyed powder is described. The composition, phases present in the alloy, volume percent, size and spacing of the phases are reported. The room temperature electronic transport properties of electrical conductivity, carrier concentration and carrier mobility are reported for each alloy and the effect of the presence of any secondary phase on the electronic transport properties is described. An mechanical mixing approach for incorporating the end compounds to result in (y)(AgSbTe2)--(1-y)(Pb 1-xSnxTe) is described and when 5 vol.% AgSbTe2 was incorporated was found to form a solid solution with the Pb1-xSn xTe phase. An initial attempt to change the carrier concentration of the Pb1-xSnxTe phase was made by adding excess Te and found that the carrier density of the alloys in this work are not sensitive to excess Te. It has been demonstrated using the processing techniques reported in this research that this material system, when appropriately doped, has the potential to perform as highly functional thermoelectric material.

Lalonde, Aaron D.

345

Cognitive humor processing: Different logical mechanisms in nonverbal cartoonsan fMRI study  

Microsoft Academic Search

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

Andrea C. Samson; Stefan Zysset; Oswald Huber

2008-01-01

346

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

Microsoft Academic Search

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 nonselectiveones,whichmayrequireinterpretationintermsbeyond the memory mechanism. To examine this possibility, we assessed decrease in differential activation during the second presentationofanidenticalface(repetitionsuppression)asanindex of person selectivity. During fMRI, pictures of personally familiar,

Motoaki Sugiura; Yoko Mano; Akihiro Sasaki; Norihiro Sadato

2010-01-01

347

Effect of processing parameters on the microstructure and mechanical properties of Alsteel composite foam  

Microsoft Academic Search

Alsteel composite foams comprise of steel hollow spheres embedded in an aluminum matrix and are processed using a gravity\\u000a casting technique. The effect of processing parameters such as casting temperature and cooling rate on the microstructure\\u000a and mechanical behavior was studied to establish structureproperty relationships. Results show that the amount and composition\\u000a of intermetallic phases present in the foam microstructure

L. J. Vendra; J. A. Brown; A. Rabiei

2011-01-01

348

Finite element analysis for the mechanical features of resistance spot welding process  

Microsoft Academic Search

In this paper, a 2D axisymmetric model of thermo-elasticplastic finite element method (FEM) is developed to analyze the mechanical behavior of resistance spot welding (RSW) process using commercial software ANSYS. A transient temperature field obtained from a prior performed thermalelectrical simulation of RSW process is applied as nodal load on the model. The temperature-dependent properties and plastic behavior of materials

Zhigang Hou; Ill-Soo Kim; Yuanxun Wang; Chunzhi Li; Chuanyao Chen

2007-01-01

349

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

350

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

SciTech Connect

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

Scobbo, J.J. Jr.

1989-01-01

351

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

352

Trapping and Probing Antihydrogen  

SciTech Connect

Precision spectroscopy of antihydrogen is a promising path to sensitive tests of CPT symmetry. The most direct route to achieve this goal is to create and probe antihydrogen in a magnetic minimum trap. Antihydrogen has been synthesized and trapped for 1000s at CERN by the ALPHA Collaboration. Some of the challenges associated with achieving these milestones will be discussed, including mixing cryogenic positron and antiproton plasmas to synthesize antihydrogen with kinetic energy less than the trap potential of .5K. Recent experiments in which hyperfine transitions were resonantly induced with microwaves will be presented. The opportunity for gravitational measurements in traps based on detailed studies of antihydrogen dynamics will be described. The talk will conclude with a discussion future antihydrogen research that will use a new experimental apparatus, ALPHA-I.

Wurtele, Jonathan [UC Berkeley and LBNL

2013-03-27

353

Inertial measurement with trapped particles: A microdynamical system  

SciTech Connect

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

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

2010-04-05

354

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

PubMed

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

Peremen, Ziv; Lamy, Dominique

2014-02-01

355

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

PubMed

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

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

2014-09-01

356

City of Santa Monica This page outlines solar PV incentives, financing mechanisms, permitting process, and interconnection  

E-print Network

City of Santa Monica This page outlines solar PV incentives, financing mechanisms, permitting process, and interconnection information for the City of Santa Monica and the utility that serves its an Installer | Financing | Incentives | Permitting | Interconnection Contact Information City of Santa Monica

357

On-line sensing and modeling of mechanical impedance in robotic food processing  

Microsoft Academic Search

Measurement of mechanical impedance is useful in robotic food processing. In cutting meat, fish, and other inhomogeneous objects by means of a robotic cutter, for instance, it is useful to sense the transition regions between soft meat, hard meat, fat, shin, and bone. Product quality and yield can be improved through this, by accurately separating the desired product from the

C. W. de Silva; J. H. Gut

1995-01-01

358

Mechanical and thermal properties of lime and hemp concrete (hempcrete) manufactured by a projection process  

Microsoft Academic Search

Concrete blocks, made of a mixture of lime and hemp shives (also called hemp hurds), have been manufactured by a recently developed projection process. Lime carbonatation kinetics is determined by X-ray diffraction. Density measurements are made within blocks, and thermal and mechanical properties are measured (flexural strength, compression strength and hardness). The main observations are moderate density variations within a

S. Elfordy; F. Lucas; F. Tancret; Y. Scudeller; L. Goudet

2008-01-01

359

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

360

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

361

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

E-print Network

important and complex among them is continuous casting. In fact most of the steel made today is produced and cracking problems in processes such as the continuous casting of steel. The high cost of plant experiments-mechanical model has been developed to simulate the continuous casting of shaped sections, such as used for thin

Thomas, Brian G.

362

Coupled mechanical and chemical processes in engineered geothermal reservoirs with dynamic permeability  

Microsoft Academic Search

A model is developed to represent mechanical strain, stress-enhanced dissolution, and shear dilation as innately hysteretic and interlinked processes in rough contacting fractures. The model is incorporated into a numerical simulator designed to examine permeability change and thermal exchange in chemically active and deformable fractured reservoirs. A candidate engineered geothermal reservoir system (EGS) is targeted. The mechanistic model is able

Joshua Taron; Derek Elsworth

2010-01-01

363

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

E-print Network

City of San Diego This page outlines solar PV incentives, financing mechanisms, permitting process, and interconnection information for the City of San Diego and the utility that serves its territory, San Diego Gas | Incentives | Permitting | Interconnection Contact Information City of San Diego Department of Development

364

Mechanism of Surface Finishing in Ultrasonic-Assisted Magnetic Abrasive Finishing Process  

Microsoft Academic Search

Ultrasonic-assisted magnetic abrasive finishing (UAMAF) integrates the use of ultrasonic vibrations and magnetic abrasive finishing (MAF) processes to finish surfaces of nanometer order within a minute's time. The present study emphasizes the mechanism of surface finishing in UAMAF. This article reports the study of the microscopic changes in the surface texture resulting from interaction of abrasives with ground workpiece surface.

Rahul S. Mulik; Pulak M. Pandey

2010-01-01

365

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

PubMed

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

366

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

367

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

NASA Astrophysics Data System (ADS)

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

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

2003-10-01

368

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

369

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

NASA Astrophysics Data System (ADS)

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

Wongsa-Ngam, Jittraporn

370

In-source decay and pseudo tandem mass spectrometry fragmentation processes of entire high mass proteins on a hybrid vacuum matrix-assisted laser desorption ionization-quadrupole ion-trap time-of-flight mass spectrometer.  

PubMed

In-source decay (ISD), although a process known for decades in mass spectrometry, has a renewed interest due to increased theoretical knowledge in fragmentation processes of large biomolecules coupled with technological improvements. We report here an original method consisting of isolating matrix-assisted laser desorption ionization (MALDI)-generated in-source fragments of large proteins and subsequently performing selective fragmentation experiments (up to four cycles) using a hybrid MALDI quadrupole ion-trap time-of-flight mass spectrometer (MALDI-QIT-TOF). This technology takes advantage of keeping high resolution on the selection of precursors and detection of fragments. It allows exhaustive N- and C-terminal sequencing of proteins. In this work, human serum albumin (HSA), ?-casein, and recombinant Tau proteins were submitted to in source decay in the MALDI source. The fragments were stored in the ion-trap and submitted to sequential collision-induced dissociation (CID). Finally, ISD and pseudo MS(n) were performed on oxidized Tau protein and acetylated bovine serum albumin to identify amino acid modifications. This work highlights the potential of the MALDI-QIT-TOF instrument for pseudo MS(n) strategies and top down proteomics. PMID:22721425

Sellami, Lyna; Belgacem, Omar; Villard, Claude; Openshaw, Matthew E; Barbier, Pascale; Lafitte, Daniel

2012-06-19

371

Application of mechanical and electrical equipment in a natural gas processing plant  

SciTech Connect

In 1984 the Northwest Pipeline Corporation purchased and installed equipment for their Ignacio, Colorado, gas processing plant to extract ethane and heavier hydrocarbons from the gas arriving at their pipeline system from various natural gas producing sources. In addition to the basic turbo-expander required to achieve the very low gas temperatures in the process, the equipment includes gas turbine driven compressors, heat recovery steam generators, and a steam turbine driven electric power generator. This paper reviews the process itself, the various mechanical and electrical equipment involved, and some of the control system utilized to tie it all together.

Lang, R.P.; Mc Cullough, B.B.

1987-01-01

372

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

373

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

374

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

Code of Federal Regulations, 2012 CFR

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

2012-10-01

375

Scaling the ion trap quantum processor.  

PubMed

Trapped atomic ions are standards for quantum information processing, serving as quantum memories, hosts of quantum gates in quantum computers and simulators, and nodes of quantum communication networks. Quantum bits based on trapped ions enjoy a rare combination of attributes: They have exquisite coherence properties, they can be prepared and measured with nearly 100% efficiency, and they are readily entangled with each other through the Coulomb interaction or remote photonic interconnects. The outstanding challenge is the scaling of trapped ions to hundreds or thousands of qubits and beyond, at which scale quantum processors can outperform their classical counterparts in certain applications. We review the latest progress and prospects in that effort, with the promise of advanced architectures and new technologies, such as microfabricated ion traps and integrated photonics. PMID:23471398

Monroe, C; Kim, J

2013-03-01

376

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

377

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

NASA Astrophysics Data System (ADS)

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

Shamdani, Amir Hossein; Khoddam, Shahin

2014-04-01

378

Increased trapping efficiency with force-assisted velocity-selective coherent population trapping  

NASA Astrophysics Data System (ADS)

We study a class of laser cooling schemes that combine velocity-selective coherent population trapping (VSCPT) with Doppler cooling mechanisms. The Doppler mechanism prevents the atoms from diffusing into the region of high momentum, thereby removing the characteristic long-time asymptotic behaviour of VSCPT where, in the end, all the atoms escape from the trap. It is shown that the transition Jg = 2 to Je = 1 while maintaining the simple field configuration present in the original VSCPT case provides the additional Doppler mechanism and leads to virtually zero temperature without the loss of atoms that characterize the original VSCPT dynamics.

Zambon, Bruno; Nienhuis, Gerard

2006-03-01

379

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

380

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

381

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.

2014-07-01

382

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

SciTech Connect

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

Ogihara, Masahiro; Ida, Shigeru [Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Duncan, Martin J., E-mail: ogihara@geo.titech.ac.j, E-mail: ida@geo.titech.ac.j, E-mail: duncan@astro.queensu.c [Queen's University, Kingston, K7L 3N6, Ontario (Canada)

2010-10-01

383

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

384

Estimation of trapping position in three-dimensional off-axis trapping with optical vortices  

NASA Astrophysics Data System (ADS)

Dynamics of micrometer-sized dielectric objects can be controlled by optical tweezers with scanning light, however, the trapped objects fail to track the scan when drag exceeds the trapping by too quick movement. On the other hand, optical vortices (OVs), which have a property of carrying angular momenta, can directly control torque on objects rather than their position. Laguerre-Gaussian (LG) beams are the most familiar examples of OV and have been studied extensively so far. Revolution of the objects trapped by the LG beams provides typical models of nonequilibrium statistical system, but stable mid-water trapping by the LG beams becomes essential to evaluate physical properties of the system without extrinsic hydrodynamic effects,. Nevertheless, off-axis revolutions of small objects trapped in mid-water by the LG beams have not yet been established with secure evidences. Here we report stable off-axis trapping of dielectric spheres in mid-water using high-quality LG beams generated by a holographic complex-amplitude modulation method. Direct evidence of the three-dimensional off-axis LG trapping was established via estimating the trapping position by measuring the change of revolution radii upon pressing the spheres onto glass walls. Resultantly, the axial trapping position was determined as about half the wavelength behind the beam waist position. This result provides a direct scientific evidence for possibility of off-axis three-dimensional trapping with a single LG beam, moreover, suggests applications as powerful tools for studying energy-conversion mechanisms and nonequilibrium nature in biological molecules under torque.

Ando, Taro; Otsu, Tomoko; Takiguchi, Yu; Ohtake, Yoshiyuki; Toyoda, Haruyoshi; Itoh, Hiroyasu

2014-08-01

385

Lift enhancement by trapped vortex  

NASA Technical Reports Server (NTRS)

The viewgraphs and discussion of lift enhancement by trapped vortex are provided. Efforts are continuously being made to find simple ways to convert wings of aircraft from an efficient cruise configuration to one that develops the high lift needed during landing and takeoff. The high-lift configurations studied here consist of conventional airfoils with a trapped vortex over the upper surface. The vortex is trapped by one or two vertical fences that serve as barriers to the oncoming stream and as reflection planes for the vortex and the sink that form a separation bubble on top of the airfoil. Since the full three-dimensional unsteady flow problem over the wing of an aircraft is so complicated that it is hard to get an understanding of the principles that govern the vortex trapping process, the analysis is restricted here to the flow field illustrated in the first slide. It is assumed that the flow field between the two end plates approximates a streamwise strip of the flow over a wing. The flow between the endplates and about the airfoil consists of a spanwise vortex located between the suction orifices in the endplates. The spanwise fence or spoiler located near the nose of the airfoil serves to form a separated flow region and a shear layer. The vorticity in the shear layer is concentrated into the vortex by withdrawal of fluid at the suction orifices. As the strength of the vortex increases with time, it eventually dominates the flow in the separated region so that a shear or vertical layer is no longer shed from the tip of the fence. At that point, the vortex strength is fixed and its location is such that all of the velocity contributions at its center sum to zero thereby making it an equilibrium point for the vortex. The results of a theoretical analysis of such an idealized flow field are described.

Rossow, Vernon J.

1992-01-01

386

Dynamic switching mechanism of conduction/set process in Cu/a-Si/Si memristive device  

NASA Astrophysics Data System (ADS)

The conduction/set processes of resistive switching have been systemically investigated for Cu/a-Si/Si electrochemical memristive devices. Experimental results indicate that the set process was driven by two different mechanisms, depending on the programming pulse amplitude: a purely electrical dielectric breakdown and a thermally assisted dielectric breakdown. For the latter process, we observe that the set time decreased exponentially with the increase in the programming pulse amplitude, whereas the former process shows amplitude independence. Through the temperature-dependent set transition characteristics, we argue that the filament growth in set process could be dominated by cation transport in the dielectric film. The thermal activation energy of Cu hopping in a-Si is extracted to be 0.16 eV.

Gao, Ligang; Lee, Shin Buhm; Hoskins, Brian; Yoo, Hyang Keun; Kang, Bo Soo

2013-07-01

387

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

388

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

389

Improved test setup for MEMS mechanical strength investigations and fabrication process qualification  

NASA Astrophysics Data System (ADS)

The mechanical stability of silicon MEMS dies is strongly influenced by the microfabrication processes, especially grinding, dicing and etching, which leave characteristic damage (defects, cracks, dislocations) in the substrate material. Specially designed mechanical tests are used to assess the resistance of micro-structures to monotonic and cyclic loading. We report on the development progress of a micromechanical test bench for reliability assessment of microstructures in 2-, 3- and 4-point bending configurations. Strain distributions and defects in micron-sized silicon devices can be investigated by in-situ testing in combination with high-resolution x-ray diffraction measurements for experimentally assessing the strain distribution.

Bandi, T.; Maeder, X.; Dommann, A.; Shea, H.; Neels, A.

2014-03-01

390

Numerical simulations of gas-liquid flow in the gas injection process with mechanical stirring  

NASA Astrophysics Data System (ADS)

Based on Euler-Euler approach, a mathematical model is established to describe gas and liquid two-phase flow in a gas injected mechanically stirred system used in hot metal desulfurization process. The influences of different impellers types and rotation methods were investigated. The results show that the predicted distribution of bubbles in the bath agrees well with experimental results. The gas-liquid flow in the gas injected-mechanically stirred system can be accurately described by the present model. Compared to the standard impeller, the improved impeller in forward stirring mode is more efficient to increase the retention time and dispersion of bubbles.

Shao, Pin; Zhang, Ting'an; Liu, Yan; Zhang, Zimu; Wang, Dongxing

2013-06-01

391

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

392

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

PubMed Central

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

Keppler, Joachim

2013-01-01

393

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

PubMed

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

Yamaguchi, Kenji; Sakurai, Yoshio

2014-10-01

394

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 de Laval-type nozzle. A coating is formed through the intensive plastic deformation of particles impacting on a substrate at a temperature below the melting point of the spray material. In the present paper the main processing parameters affecting the microstructural and mechanical behavior of metal-metal cold spray deposits are described. The effect of process parameters on grain refinement and mechanical properties were analyzed for composite particles of Al-Al2O3, Ni-BN, Cu-Al2O3, and Co-SiC. The properties of the formed nanocomposites were compared with those of the parent materials sprayed under the same conditions. The process conditions, leading to a strong grain refinement with an acceptable level of the deposit mechanical properties such as porosity and adhesion strength, are discussed.

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

2014-10-01

395

Negative-bias temperature instability induced electron trapping  

NASA Astrophysics Data System (ADS)

Despite four decades of research, the physics responsible for the negative-bias temperature instability (NBTI) in p-channel metal-oxide-silicon field-effect transistors is still unresolved. The current NBTI debate focuses on the dominance of either a hole trapping/detrapping mechanism or a hydrogen depassivation mechanism. In this study, we present NBTI-induced changes in the peak transconductance which indicate the presence of a third mechanism involving electron trapping/detrapping. The presence of this electron trapping/detrapping component adds further complexity to the very complicated NBTI phenomenon.

Campbell, J. P.; Cheung, K. P.; Suehle, J. S.; Oates, A.

2008-07-01

396

An object-oriented process tracking system for a distributed system without global clock  

E-print Network

to monitored information, design of monitoring mechanisms and use of monitored information. Two techniques are used to make the local information available to the debugger: polling and event reporting (trap). Process control is concerned with modifying... to monitored information, design of monitoring mechanisms and use of monitored information. Two techniques are used to make the local information available to the debugger: polling and event reporting (trap). Process control is concerned with modifying...

Viswanathan, Rajeswaran

2012-06-07

397

Increased oxidative stress brought on by pro-inflammatory cytokines in neurodegenerative processes and the protective role of nitrone-based free radical traps.  

PubMed

Nitrone-based free radical traps (NFTs) have been shown to be protective in several neurodegenerative models. Our research has strongly implicated that: A) several neurodegenerative conditions exhibit increased levels of pro-inflammatory cytokines which consequently result in increased levels of oxidative stress and B) that NFTs act in part by suppressing oxidative stress through suppression of the action of the cytokine cascade. Acquired Immune Deficiency Syndrome (AIDS) dementia complex (ADC) is one of several conditions where the data collected helped to develop these concepts. Novel observations include demonstration that IL-1beta acts on cultured brain glia cells to invoke protein nitration and oxidative stress and that low levels of PBN (alpha-phenyl tert-butyl nitrone) inhibit this effect. We interpret these data as indicating that PBN prevents IL-1beta mediated peroxynitrite formation. Additionally, we have found that the AIDS viral envelope protein gp120 upregulates mRNA for the cytokines TNF alpha and TNF beta in rat neonatal brain, and that PBN prevents this. Western blots of protein extracts showed upregulation of inducible nitric oxide synthase (iNOS) in gp120 treated neonatal rat brains, and that PBN prevented induction of this enzyme as well. These observations underscore the general concept that PBN inhibits the induction of genes which produce neurotoxic products, one of which is peroxynitrite formed by the reaction of nitric oxide with superoxide, and may act also by inhibiting the induction of cytokines which mediate pro-inflammatory conditions in the brain. PMID:10576433

Floyd, R A; Hensley, K; Jaffery, F; Maidt, L; Robinson, K; Pye, Q; Stewart, C

1999-01-01

398

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

PubMed

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

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

2014-05-01

399

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

SciTech Connect

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

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

1984-07-01

400

Assessing the similarity of mechanisms in motion and color processing for synchronization of visual pathways  

NASA Astrophysics Data System (ADS)

Given the great diversity of pathways into which the visual system signal splits after arriving at area V1, many researchers have proposed solutions to the 'binding problem' of reunifying the information after specialized processing. Most solutions require pathways to maintain synchrony and share information, which in turn requires some similarity of mechanisms and/or the spaces in which they operate. We examine the extent to which such similarity can occur between motion and color processing pathways, by using a multiple stage motion detection algorithm for processing color change. We first review the motion algorithm chosen, then we present a model for certain changes in hue, discuss the possible uses for such processes in the visual system, and present results of applying this model to both motion and color in this manner.

Rising, Hawley K., III

1997-06-01

401

The effect of mechanical processing procedures on the decomposition rate of silver oxide cathode material  

SciTech Connect

Divalent silver oxide/zinc (AgO/Zn) cells are in widespread use for various commercial, military, and aerospace applications. The unusually high decomposition rate of AgO in alkaline electrolytes has been a persistent problem for battery manufacturers. The effect of mechanical processing procedures on the thermal stability of AgO (silver oxide) cathode material with and without 0.4% Pb(NO{sub 3}){sub 2} as an additive is reported. The process of producing AgO cathode pellets by mixing, pelletizing, breaking, grading, and repelletizing is reported. The finding that the mechanical reprocessing affected many of the important properties of silver oxide cathode material is reported.

Takeda, Kazutoshi [Seiko Instruments, Inc., Chiba (Japan). Patent and Intellectual Property Dept.

1996-02-01

402

Analysis of optical trap mediated aerosol coalescence  

NASA Astrophysics Data System (ADS)

The use of optical tweezers for the analysis of aerosols is valuable for understanding the dynamics of atmospherically relevant particles. However to be able to make accurate measurements that can be directly tied to real-world phenomena it is important that we understand the influence of the optical trap on those processes. One process that is seemingly straightforward to study with these techniques is binary droplet coalescence, either using dual beam traps, or by particle collision with a single trapped droplet. This binary coalescence is also of interest in many other processes that make use of dense aerosol sprays such as spray drying and the use of inhalers for drug delivery in conditions such as asthma or hay fever. In this presentation we discuss the use of high speed (~5000 frames per second) video microscopy to track the dynamics of particles as they approach and interact with a trapped aqueous droplet and develop this analysis further by considering elastic light scattering from droplets as they undergo coalescence. We find that we are able to characterize the re-equilibration time of droplets of the same phase after they interact and that the trajectories taken by airborne particles influenced by an optical trap are often quite complex. We also examine the role of parameters such as the salt concentration of the aqueous solutions used and the influence of laser wavelength.

Mistry, N. S.; Power, R.; Anand, S.; McGloin, D.; Almohamedi, A.; Downie, M.; Reid, J. P.; Hudson, A. J.

2012-10-01

403

A systematic study on evolution mechanism of titanate nanostructures in the hydrothermal process  

NASA Astrophysics Data System (ADS)

A systematic study on hydrothermal treatment of titania recording the changes of morphologies of titanate nanostructures was performed by subtly controlled termination of reaction and capture of intermediates. During the hydrothermal process, rapid coalescence of nanoparticles first occurred, followed by exfoliation of large aggregated moieties in their peripheries into nanosheets. The nanosheets were then rolled up to form short nanotubes. Afterwards, the nanotubes transformed into long ones, which eventually assembled into nanowires. This is a stepwise evolution process common for alkaline hydrothermal transitions. The oriented attachment (OA) model plays a vital role here, and the Oswald ripening (OR) mechanism appears to be effective as well.

Lu, Haiqiang; Zhao, Jianghong; Li, Li; Zheng, Jianfeng; Zhang, Lexi; Gong, Liming; Wang, Zhijian; Zhu, Zhenping

2011-05-01

404

Overview of Mechanisms Involved During the Quenching and Partitioning Process in Steels  

NASA Astrophysics Data System (ADS)

The application of the quenching and partitioning (Q&P) process in steels involves a microstructural evolution that is more complex than just the formation of martensite followed by carbon partitioning from martensite to austenite. Examples of this complexity are the formation of epitaxial ferrite during the first quenching step and the formation of bainite, carbides, and carbon gradients as well as migration of martensite/austenite interfaces during the partitioning step. In this work, recent investigations on the mechanisms controlling microstructural changes during the application of the Q&P process are evaluated, leading to phase-formation based concepts for the design of Q&P steels.

Santofimia, M. J.; Zhao, L.; Sietsma, J.

2011-12-01

405

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

SciTech Connect

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

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

2006-12-04

406

Heating of trapped ultracold atoms by collapse dynamics  

E-print Network

{The Continuous Spontaneous Localization (CSL) theory alters the Schr\\"odinger equation. It describes wave function collapse as a dynamical process instead of an ill-defined postulate, thereby providing macroscopic uniqueness and solving the so-called measurement problem of standard quantum theory. CSL contains a parameter $\\lambda$ giving the collapse rate of an isolated nucleon in a superposition of two spatially separated states and, more generally, characterizing the collapse time for any physical situation. CSL is experimentally testable, since it predicts some behavior different from that predicted by standard quantum theory. One example is the narrowing of wave functions, which results in energy imparted to particles. Here we consider energy given to trapped ultra-cold atoms. Since these are the coldest samples under experimental investigation, it is worth inquiring how they are affected by the CSL heating mechanism. We examine the CSL heating of a BEC in contact with its thermal cloud. Of course, other mechanisms also provide heat and also particle loss. From varied data on optically trapped cesium BEC's, we present an energy audit for known heating and loss mechanisms. The result provides an upper limit on CSL heating and thereby an upper limit on the parameter $\\lambda$. We obtain $\\lambda\\lesssim 1(\\pm1)\\times 10^{-7}$sec$^{-1}$.}

Franck Lalo; William J. Mullin; Philip Pearle

2014-09-18

407

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

NASA Technical Reports Server (NTRS)

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

Przewlocka, H.; Siedlecka, J.

1982-01-01

408

Uncertainty analysis of thermo-hydro-mechanical coupled processes in heterogeneous porous media  

Microsoft Academic Search

In this paper we present an uncertainty analysis of thermo-hydro-mechanical (THM) coupled processes in a typical geothermal\\u000a reservoir in crystalline rock. Fracture and matrix are treated conceptually as an equivalent porous medium, and the model\\u000a is applied to available data from the Urach Spa and Falkenberg sites (Germany). The finite element method (FEM) is used for\\u000a the numerical analysis of

Norihiro Watanabe; Wenqing Wang; Christopher I. McDermott; Takeo Taniguchi; Olaf Kolditz

2010-01-01

409

Fertilization and pH effects on processes and mechanisms controlling dissolved inorganic phosphorus in soils  

Microsoft Academic Search

We used of a set of mechanistic adsorption models (1-pK TPM, ion exchange and Nica-Donnan) within the framework of the component additive (CA) approach in an attempt to determine the effect of repeated massive application of inorganic P fertilizer on the processes and mechanisms controlling the concentration of dissolved inorganic phosphorus (DIP) in soils. We studied the surface layer of

Nicolas Devau; Philippe Hinsinger; Edith Le Cadre; Bruno Colomb; Frdric Grard

2011-01-01

410

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

Microsoft Academic Search

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

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

2006-01-01

411

Deposition mechanisms of thermal barrier coatings in the solution precursor plasma spray process  

Microsoft Academic Search

In an effort to understand the deposition mechanisms in the solution precursor plasma spray (SPPS)a promising method for the deposition of highly-durable thermal barrier coatingssome model spray experiments were performed. In the SPPS process, an aqueous chemical precursor feedstock, which results in a ZrO27wt.%Y2O3 ceramic solid solution coating, is injected into the plasma jet and the coating is deposited on

Liangde Xie; Xinqing Ma; Eric H. Jordan; Nitin P. Padture; Danny T. Xiao; Maurice Gell

2004-01-01

412

A Biochip with a 3D microfluidic architecture for trapping white blood cells  

PubMed Central

We present a microfluidic biochip for trapping single white blood cells (WBCs). The novel biochip, microfabricated using standard surface micromachining processes, consists of an array of precisely engineered microholes that confine single cells in a tight, three dimensional space and mechanically immobilize them. A high (> 87%) trapping efficiency was achieved when WBC-containing samples were delivered to the biochip at the optimal pressure of 3 psi. The biochip can efficiently trap up to 7,500 cells, maintaining a high trapping efficiency even when the number of cells is extremely low (~200 cells). We believe that the developed biochip can be used as a standalone unit in a biology/clinical lab for trapping WBCs as well as other cell types and imaging them using a standard fluorescent microscope at the single cell level. Furthermore, it can be integrated with other miniaturized optical modules to construct a portable platform for counting a wide variety of cells and therefore it can be an excellent tool for monitoring human diseases at the point-of-care. PMID:23935241

Tripathi, Anurag; Riddell, James; Chronis, Nikos

2013-01-01

413

Electrical characteristics and deep level traps study of Au/ZnO:H Schottky diodes  

NASA Astrophysics Data System (ADS)

The electrical characteristics and the deep level traps of Au Schottky contacts on ZnO:H films have been investigated by temperature-dependent current-voltage (I-V) and deep level transient spectroscopy (DLTS) measurements. The films were deposited with the DC-sputtering, varying the H flow rate in the Ar/H sputtering gas, so that the hydrogen per volume concentration [H2] was 0%, 20%, 33.3%, 50% and 66.6%. We found that for the Schottky diodes with [H2] = 33.3% thermionic emission is the dominant current transport process at low forward voltage, taking into consideration the lateral fluctuations of the barrier height described by a Gaussian distribution model. The domination of trap-assisted current transport mechanisms is possible in the diodes with [H2] = 0%, 20%, 50% and 66.6%. DLTS spectra revealed two electron traps, with activation energies of 0.29 and 0.21 eV, often observed in ZnO and related to intrinsic defects. The trap concentrations are significantly lower in the 33.3% H2 diodes compared to the 0% H2 ones, indicating an interaction of these traps with hydrogen.

Tsiarapas, Christos; Girginoudi, Dimitra; Georgoulas, Nikolaos

2014-11-01

414

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

NASA Astrophysics Data System (ADS)

Experimental results of electron paramagnetic resonance spectra, X-ray diffraction, scanning electron microscopy and infrared spectroscopy demonstrate that the kinetic of the physical and chemical processes that takes place during prolonged intensive mechanical processing (MP, 03120 min) of powder mixtures of 50%wt ZnO+50%wt MnO 2 can be described as a three stage process. (1) 030 min, particles destruction, formation of superficial defects, fast increment of sample average temperature (from 290 to 600 K) and annealing of defects with the lowest energy of activation Eac. (2) 30390 min, further particle destruction, slow increment of sample average temperature (from 600 to 700 K), formation and growth of a very disordered layer of ?-MnO2 around ZnO particles, dehydration of MnO 2, formation of solid solution of Mn 2+ ions in ZnO, formation of nano-quasiamorphous states in the ZnO-MnO 2 mixture and onset of the formation of the ZnMnO 3 phase. (3) 3903120 min, the sample average temperature remains constant ( 700 K), the reaction is completed and the spinel ZnMnO 3 phase with a unit cell a=8.431(1) and space group Fd3m is the only phase present in the sample. No ferromagnetism at room temperature was detected in this study.

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

2011-10-01

415

Effect of Processing Parameters on the Mechanical Properties of Interstitial Free Steel Subjected to Friction Stir Processing  

NASA Astrophysics Data System (ADS)

In the present work, the effect of friction stir processing parameters on the mechanical properties of an interstitial free steel was studied. Four rotating speeds (800, 1250, 1600, 2000 rpm) and two traverse speeds (31.5 and 63 mm/min) were employed. On both sides of specimens, a nanograin layer with the thickness and nanograins of 150 ?m and 50-100 nm were formed, respectively. For the specimen processed at rotating speed of 1600 rpm and the traverse speed of 31.5 mm/min, the maximum strength was achieved, which was about 80% increase in the strength comparing to that of base material. For constant traverse speed, the increase in the rotation speed from 800 to 1600 rpm led to a decrease in uniform and total elongation of friction stir processed samples. By contrast, when the rotating speed exceeded 1600 rpm, the uniform and total elongation was increased again, while there was a drop in strength. The results of microhardness indicate more than threefold increase in the hardness of the stirred zone comparing to that of base material.

Chabok, A.; Dehghani, K.

2013-05-01

416

Steam Trap Management  

E-print Network

problemA of water hammer and high back pressure. ? Exorbitantly hi~h percentage of cold trapA. ? External steam leaks within the steam trap stations, bypasA valves and/or strainer blowdown valvefl open, blowin~ steam. ! I ? Dirt nssociated... that falls to the "botto Une" on the PE,1. stat"ment. Up to a 500~ return on investment. ? Cash flo\\ol breRk even of fi months or ? Tmproved safety and housekeeping. ? With these henefits at stake,you mighl wonde morc' companies havcn' t i nsti tuted...

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

417

The Reusable Astronomy Portal (TRAP)  

NASA Astrophysics Data System (ADS)

The Reusable Astronomy Portal (TRAP) aims to provide a common platform for rapidly deploying Astronomy Archives to the web. TRAP is currently under development for both the VAO Data Discovery Portal and the MAST Multi-Mission Portal (Figure 1). TRAP consists of 2 major software packages: the TRAP Client and the TRAP Server. The TRAP framework allows developers to deploy the Server, connect to data resources, then focus on building custom tools for the Client. TRAP is built upon proven industry technologies including the Ext/JS JavaScript Component Library, Mono.NET Web Services, and JSON message based APIs. The multi-layered architecture of TRAP decouples each layer: Client, Service and Data Access, enabling each to evolve independently over time. Although currently deployed to provide astronomy science data access, the TRAP architecture is flexible enough to thrive in any distributed data environment.

Donaldson, T.; Rogers, A.; Wallace, G.

2012-09-01

418

Field evaluation of four widely used mosquito traps in Central Europe  

PubMed Central

Background To monitor adult mosquitoes several trapping devices are available. These are differently constructed and use various mechanisms for mosquito attraction, thus resulting in different trapping sensitivities and efficacies for the various species. Mosquito monitoring and surveillance programs in Europe use various types of mosquito traps, but only a few comparisons have been conducted so far. This study compared the performance of four commercial trapping devices, which are commonly used in Europe. Methods Four different traps, Biogents Sentinel trap (BG trap), Heavy Duty Encephalitis Vector Survey trap (EVS trap), Centres for Disease Control miniature light trap (CDC trap) and Mosquito Magnet Patriot Mosquito trap (MM trap) were compared in a 4??4 latin square study. In the years 2012 and 2013, more than seventy 24-hour trap comparisons were conducted at ten different locations in northern and southern Germany, representing urban, forest and floodplain biotopes. Results Per 24-hour trapping period, the BG trap caught the widest range of mosquito species, the highest number of individuals of the genus Culex as well as the highest number of individuals of the species Ochlerotatus cantans, Aedes cinereus/geminus, Oc. communis and Culex pipiens/torrentium. The CDC trap revealed best performance for Aedes vexans, whereas the MM trap was most efficient for mosquitoes of the genus Anopheles and the species Oc. geniculatus. The EVS trap did not catch more individuals of any genus or species compared to the other three trapping devices. The BG trap caught the highest number of individuals per trapping period in urban environments as well as in wet forest, while the CDC trap caught the highest number of individuals in the floodplain biotopes. Additionally, the BG trap was most efficient for the number of mosquito species in urban locations. Conclusion The BG trap showed a significantly better or similar performance compared to the CDC, EVS or MM trap with regard to trapping efficacy for most common mosquito species in Germany, including diversity of mosquito species and number of mosquitoes per trapping period. Thus, the BG trap is probably the best solution for general monitoring or surveillance programs of adult mosquitoes in Central Europe. PMID:24924481

2014-01-01

419

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

PubMed Central

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

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

2014-01-01

420

Measurement of Trap Length for an Optical Trap  

NASA Technical Reports Server (NTRS)

The trap length along the beam axis for an optical trap formed with an upright, oil-immersion microscope was measured. The goals for this effort were twofold. It was deemed useful to understand the depth to which an optical trap can reach for purposes of developing a tool to assist in the fabrication of miniature devices. Additionally, it was desired to know whether the measured trap length favored one or the other of two competing theories to model an optical trap. The approach was to trap a microsphere of known size and mass and raise it from its initial trap position. The microsphere was then dropped by blocking the laser beam for a pre-determined amount of time. Dropping the microsphere in a free-fall mode from various heights relative to the coverslip provides an estimate of how the trapping length changes with depth in water in a sample chamber on a microscope slide. While it was not possible to measure the trap length with sufficient precision to support any particular theory of optical trap formation, it was possible to find regions where the presence of physical boundaries influenced optical traps, and determine that the trap length, for the apparatus studied, is between 6 and 7 m. These results allow more precise control using optical micromanipulation to assemble miniature devices by providing information about the distance over which an optical trap is effective.

Wrbanek, Susan Y.

2009-01-01

421

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

PubMed Central

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

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

2010-01-01

422

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

PubMed

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

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

2010-05-15

423

HWVP Iodine Trap Evaluation  

SciTech Connect

This report details our assessment of the chemistry of the planned Hanford Waste Vitrification Plant (HWVP) off-gas system and its impact on the applicability of known iodine removal and control methods. To predict the gaseous species in the off-gas system, we completed thermodynamic calculations to determine theoretical equilibrium concentrations of the various potential chemical species. In addition, we found that HWVP pilot-plant experiments were generally consistent with the known chemistry of the individual elements present in the off gas. Of the known trapping techniques for radioiodine, caustic scrubbing and silver-containing sorbents are, in our opinion, the most attractive methods to reduce the iodine concentration in the HWVP melter off gas (MOG) after it has passed through the high-efficiency particulate air (HEPA) filter. These two methods were selected because they (1) have demonstrated retention factors (RFs), ratio of amount in and amount out, of 10 to 1000, which would be sufficient to reduce the iodine concentration in the MOG to below regulatory limits; (2) are simple to apply; (3) are resistant to oxidizing gases such as NOx; (4) do not employ highly hazardous or highly corrosive agents; (5) require containment vessels constructed or common materials; (6) have received extensive laboratory development; (7) and the radioactive wastes produced should be easy to handle. On the basis of iodine trapping efficiency, simplicity of operation, and waste management, silver sorbents are superior to caustic scrubbing, and, or these sorbents, we prefer the silver zeolites. No method has been fully demonstrated, from laboratory-scale through pilot-plant testing, to be an effective iodine trap at the low iodine concentration (2 x 10-11 mol I/L) expected in the MOG of the HWVP in the presence of the other gaseous off gas components. In terms of compatibility of the trapping technology with the components in the MOG, there is some question about the resistance of the silver zeolite's aluminosilicate matrix to the fluoride component in the off gas. The caustic scrubber has no compatibility problems with the MOG off gas; however, the acidic components such as CO2 will increase the volume of waste produced and could affect the efficiency of the iodine trapping. To apply these gaseous iodine trapping technologies to the HWVP, further development work would be required. Neither method has been demonstrated at the very low iodine concentrations that exist in the off gas, which are 0.01% to 1% of the found in nuclear fuel dissolver off gases for which these technologies were developed. Furthermore, the large excess of other reactive and trappable gases in the HWVP off gas imposes a heavy load on the trapping medium, could impede iodine trapping, and could have deleterious effects on the trapping medium itself. For silver zeolites, other trappable gases such as chlorine, which are in gross excess of the iodine in the off gas, will compete for the active sites in the silver zeolite. In applying a silver zeolite to the HWVP, 99-9% of the silver would be used to trap chlorine with less than 0.1% of the silver employed in the zeolite bed used for iodine trapping. It is also difficult to predict what will happen when the aluminosilicate framework of the zeolite is exposed to the reactive gas, HF, which is also present in the off gas and is known to attack silicates. In the case of caustic scrubbing, because of the low iodine concentration in the off gas, essentially all of the caustic will be used for CO2 removal, a small fraction for chlorine and fluorine removal, and a trace amount for iodine removal. NO2, which should exist largely as NO, will not be removed.

Burger, Leland L.; Scheele, Randall D.

2004-09-24

424

Production of green juice with an intensive thermo-mechanical fractionation process. Part I: Effects of processing conditions on the dewatering kinetics  

Microsoft Academic Search

The thermally assisted mechanical dewatering (TAMD) process is a new intensive solid\\/liquid separation device. When applied to nature-wet biomass, the TAMD process significantly enhances the separation yield. The TAMD process couples in one stage a mechanical dewatering at low pressure (Papplied=300kPa in the present study) with a moderated heating (Twall?90C). An increment of pressure can be applied in a second

P. Arlabosse; M. Blanc; S. Kerfa; A. Fernandez

2011-01-01

425

Noise as a mechanism of anomalous face processing among persons with Schizophrenia  

PubMed Central

There is substantial evidence that people with Schizophrenia (SCZ) have altered visual perception and cognition, including impaired face processing. However, the mechanism(s) underlying this observation are not yet known. Eye movement studies have found that people with SCZ do not direct their gaze to the most informative regions of the face (e.g., the eyes). This suggests that SCZ patients may be less able to extract the most relevant face information and therefore have decreased calculation efficiency. In addition, research with non-face stimuli indicates that SCZ is associated with increased levels of internal noise. Importantly, both calculation efficiency and internal noise have been shown to underpin face perception among healthy observers. Therefore, the current study applies noise masking to upright and inverted faces to determine if face processing deficits among those with SCZ are the result of changes in calculation efficiency, internal noise, or both. Consistent with previous results, SCZ participants exhibited higher contrast thresholds in order to identify masked target faces. However, higher thresholds were associated with increases in internal noise but unrelated to changes in calculation efficiency. These results suggest that SCZ-related face processing deficits are the result of a decreased noise-to-signal ratio. The source of increased processing noise among these patients is unclear, but may emanate from abnormal neural dynamics. PMID:23882228

Christensen, Bruce K.; Spencer, Justine M. Y.; King, Je