A Novel Repair Technique for the Internal Thermal Control System Dual-Membrane Gas Trap

NASA Technical Reports Server (NTRS)

Leimkuehler, Thomas O.; Patel, Vipul; Reeves, Daniel R.; Holt, James M.

2005-01-01

A dual-membrane gas trap is currently used to remove gas bubbles from the Internal Thermal Control System (ITCS) coolant on board the International Space Station (ISS). The gas trap consists of concentric tube membrane pairs, comprised of outer hydrophilic tubes and inner hydrophobic fibers. Liquid coolant passes through the outer hydrophilic membrane, which traps the gas bubbles. The inner hydrophobic fiber allows the trapped gas bubbles to pass through and vent to the ambient atmosphere in the cabin. The gas trap was designed to last for the entire lifetime of the ISS, and therefore was not designed to be repaired. However, repair of these gas traps is now a necessity due to contamination from the on-orbit ITCS fluid and other sources on the ground as well as a limited supply of flight gas traps. This paper describes a novel repair technique that has been developed that will allow the refurbishment of contaminated gas traps and their return to flight use.

The merger of small and large black holes

NASA Astrophysics Data System (ADS)

Mösta, P.; Andersson, L.; Metzger, J.; Szilágyi, B.; Winicour, J.

2015-12-01

We present simulations of binary black-hole mergers in which, after the common outer horizon has formed, the marginally outer trapped surfaces (MOTSs) corresponding to the individual black holes continue to approach and eventually penetrate each other. This has very interesting consequences according to recent results in the theory of MOTSs. Uniqueness and stability theorems imply that two MOTSs which touch with a common outer normal must be identical. This suggests a possible dramatic consequence of the collision between a small and large black hole. If the penetration were to continue to completion, then the two MOTSs would have to coalesce, by some combination of the small one growing and the big one shrinking. Here we explore the relationship between theory and numerical simulations, in which a small black hole has halfway penetrated a large one.

Capturing a flavivirus pre-fusion intermediate.

PubMed

Kaufmann, Bärbel; Chipman, Paul R; Holdaway, Heather A; Johnson, Syd; Fremont, Daved H; Kuhn, Richard J; Diamond, Michael S; Rossmann, Michael G

2009-11-01

During cell entry of flaviviruses, low endosomal pH triggers the rearrangement of the viral surface glycoproteins to a fusion-active state that allows the release of the infectious RNA into the cytoplasm. In this work, West Nile virus was complexed with Fab fragments of the neutralizing mAb E16 and was subsequently exposed to low pH, trapping the virions in a pre-fusion intermediate state. The structure of the complex was studied by cryo-electron microscopy and provides the first structural glimpse of a flavivirus fusion intermediate near physiological conditions. A radial expansion of the outer protein layer of the virion was observed compared to the structure at pH 8. The resulting approximately 60 A-wide shell of low density between lipid bilayer and outer protein layer is likely traversed by the stem region of the E glycoprotein. By using antibody fragments, we have captured a structural intermediate of a virus that likely occurs during cell entry. The trapping of structural transition states by antibody fragments will be applicable for other processes in the flavivirus life cycle and delineating other cellular events that involve conformational rearrangements.

Vacuum-insulated catalytic converter

DOEpatents

Benson, David K.

2001-01-01

A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

Efficacy of two synthetic food-odor lures for Mexican fruit flies (Diptera: Tephritidae) is determined by trap type.

PubMed

Robacker, David C; Czokajlo, Darek

2005-10-01

Sterile mass-reared Mexican fruit flies, Anastrepha ludens (Loew), were trapped in a citrus orchard by using multilure traps and cylindrical sticky traps baited with Advanced Pheromone Technologies Anastrepha fruit fly (AFF) lures or Suterra BioLure two-component (ammonium acetate and putrescine) MFF lures (BioLures). The cylinder trap/AFF lure combination was the best trap over the first 6 wk, the multilure trap/BioLure combination was best during weeks 6-12, and the multilure trap/AFF lure combination was best during the last 6 wk. The multilure trap/BioLure combination was best overall by 36% over the cylinder trap/AFF lure combination, and 57% over the multilure trap/AFF lure combination. Cylinder traps with BioLures were the least effective trap/lure combination throughout the experiment, capturing only half as many flies as cylinder traps with AFF lures. Captures with cylinder traps baited with either lure and multilure traps with BioLures were female biased. For the most part, both lures remained highly attractive and emitted detectable amounts of attractive components under hot field conditions for the duration of the 18-wk experiment. Total emission of ammonia was 4 times greater and 1-pyrroline at least 10 times greater from AFF lures compared with BioLures. Correlations of trap and lure performance with ammonia emission and weather were determined, but no conclusions were possible. Results indicate that BioLures would be the lure of choice in multilure or other McPhail-type traps and AFF lures would be superior with most sticky traps or kill stations that attract flies to outer (not enclosed) surfaces.

Mitochondrial Protein Synthesis, Import, and Assembly

PubMed Central

Fox, Thomas D.

2012-01-01

The mitochondrion is arguably the most complex organelle in the budding yeast cell cytoplasm. It is essential for viability as well as respiratory growth. Its innermost aqueous compartment, the matrix, is bounded by the highly structured inner membrane, which in turn is bounded by the intermembrane space and the outer membrane. Approximately 1000 proteins are present in these organelles, of which eight major constituents are coded and synthesized in the matrix. The import of mitochondrial proteins synthesized in the cytoplasm, and their direction to the correct soluble compartments, correct membranes, and correct membrane surfaces/topologies, involves multiple pathways and macromolecular machines. The targeting of some, but not all, cytoplasmically synthesized mitochondrial proteins begins with translation of messenger RNAs localized to the organelle. Most proteins then pass through the translocase of the outer membrane to the intermembrane space, where divergent pathways sort them to the outer membrane, inner membrane, and matrix or trap them in the intermembrane space. Roughly 25% of mitochondrial proteins participate in maintenance or expression of the organellar genome at the inner surface of the inner membrane, providing 7 membrane proteins whose synthesis nucleates the assembly of three respiratory complexes. PMID:23212899

Trapping of microwave radiation in hollow polypyrrole microsphere through enhanced internal reflection: A novel approach

PubMed Central

Panigrahi, Ritwik; Srivastava, Suneel K.

2015-01-01

In present work, spherical core (polystyrene, PS)/shell (polypyrrole, PPy) has been synthesized via in situ chemical oxidative copolymerization of pyrrole (Py) on the surface of sulfonated PS microsphere followed by the formation of hollow polypyrrole (HPPy) shell by dissolving PS inner core in THF. Thereafter, we first time established that such fabricated novel art of morphology acts as a conducting trap in absorbing electromagnetic (EM) wave by internal reflection. Further studies have been extended on the formation of its silver nanocomposites HPPy/Ag to strengthen our contention on this novel approach. Our investigations showed that electromagnetic interference (EMI) shielding efficiency (SE) of HPPy (34.5-6 dB) is significantly higher compared to PPy (20-5 dB) in the frequency range of 0.5-8 GHz due to the trapping of EM wave by internal reflection. We also observed that EMI shielding is further enhanced to 59–23 in 10 wt% Ag loaded HPPy/Ag-10. This is attributed to the simultaneous contribution of internal reflection as well as reflection from outer surface. Such high EMI shielding capacity using conducting polymers are rarely reported. PMID:25560384

Contamination control device

DOEpatents

Clark, Robert M.; Cronin, John C.

1977-01-01

A contamination control device for use in a gas-insulated transmission bus consisting of a cylindrical center conductor coaxially mounted within a grounded cylindrical enclosure. The contamination control device is electrically connected to the interior surface of the grounded outer shell and positioned along an axial line at the lowest vertical position thereon. The contamination control device comprises an elongated metallic member having a generally curved cross-section in a first plane perpendicular to the axis of the bus and having an arcuate cross-section in a second plane lying along the axis of the bus. Each opposed end of the metallic member and its opposing sides are tapered to form a pair of generally converging and downward sloping surfaces to trap randomly moving conductive particles in the relatively field-free region between the metallic member and the interior surface of the grounded outer shell. The device may have projecting legs to enable the device to be spot welded to the interior of the grounded housing. The control device provides a high capture probability and prevents subsequent release of the charged particles after the capture thereof.

ATS-6 - Synchronous orbit trapped radiation studies with an electron-proton spectrometer

NASA Technical Reports Server (NTRS)

Walker, R. J.; Swanson, R. L.; Winckler, J. R.; Erickson, K. N.

1975-01-01

The paper discusses the University of Minnesota experiment on ATS-6 designed to study the origin and dynamics of high-energy electrons and protons in the outer radiation belt and in the near-earth plasma sheet. The experiment consists of two nearly identical detector assemblies, each of which is a magnetic spectrometer containing four gold-silicon surface barrier detectors. The instrument provides a clean separation between protons and electrons by the combination of pulse height analysis and magnetic deflection.

Trapped magnetic field of a mini-bulk magnet using YBaCuO at 77 K

NASA Astrophysics Data System (ADS)

Fujimoto, Hiroyuki; Kamijo, Hiroki

2001-09-01

Melt-processed rare earth (RE)123 superconductors have a high Jc at 77 K and high magnetic field. Solidification processes for producing (L)RE123 superconductors and pinning centers in the (L)RE123 matrix are effective for obtaining high Jc, leading to high-field application as a superconducting quasi-permanent bulk magnet with the liquid nitrogen refrigeration. One of the promising applications is a superconducting magnet for the magnetically levitated train. We fabricated a mini-superconducting bulk magnet of 200×100 mm2, consisting of 18 bulks, which are a square 33 mm on a side and 10 mm in thickness, and magnetized the mini-magnet by field cooling. The mini-magnet showed the trapped magnetic field of larger than 0.1 T on the surface of the outer vessel of the magnet. The present preliminary study discusses trapped magnetic field properties of the mini-bulk magnet using YBaCuO superconductors at 77 K.

Effect of Ion Sputtering on Interface Chemistry and Electrical Properties of an Gaas (100) Schottky Contacts

NASA Technical Reports Server (NTRS)

Wang, Y. X.; Holloway, P. H.

1984-01-01

Auger and electron photoelectron spectroscopy were used to measure the extent of As depletion during 1 keV to 5 keV argon sputtering of GaAs surfaces. This depletion was correlated with a general decrease in the barrier height of the rectifying Au contact deposited in situ. However, nondestructive angle resolved XPS measurements showed As was depleted at the outer surface more by 1 keV than 3 keV argon. These effects are explained based on a combined work effective work function model and creation of a donor like surface damage layer. The donor layer was correlated with As depletion by sputtering. Deep level trap formation and annealing of sputtering effects were studied.

On the sputter alteration of regoliths of outer solar system bodies

NASA Technical Reports Server (NTRS)

Hapke, B.

1986-01-01

The present theoretical and experimental consideration of processes that are expected to occur when the porous regoliths on outer solar system bodies lacking atmospheres are subjected to energetic ion bombardment indicates that porosity reduces the effective sputtering yield of a soil by more than an order of magnitude. Between 90 and 97 percent of the sputtered atoms are trapped within the regolith and subjected to differential desorption fractionation, which emerges as the most important path for the alteration of chemical and optical properties in sputtered regoliths. Sputtered porous mixtures of water, ammonia and methane frosts suffer a loss of H, and surface reactions of C, N, and O that should yield complex hydrocarbons and carbohydrates; such reactions may have played a role in the formation of carbonaceous chondrites' matrix material prior to agglomeration.

Microelectrophoresis of a bilayer-coated silica bead in an optical trap: application to enzymology.

PubMed

Galneder, R; Kahl, V; Arbuzova, A; Rebecchi, M; Rädler, J O; McLaughlin, S

2001-05-01

We describe an apparatus that combines microelectrophoresis and laser trap technologies to monitor the activity of phosphoinositide-specific phospholipase C-delta1 (PLC-delta) on a single bilayer-coated silica bead with a time resolution of approximately 1 s. A 1-microm-diameter bead was coated with a phospholipid bilayer composed of electrically neutral phosphatidylcholine (PC) and negatively charged phosphatidylinositol 4,5-bisphosphate (2% PIP2) and captured in a laser trap. When an AC field was applied (160 Hz, 20 V/cm), the electrophoretic force produced a displacement of the bead, Delta(x), from its equilibrium position in the trap; Delta(x), which was measured using a fast quadrant diode detector, is proportional to the zeta potential and thus to the number of PIP2 molecules on the outer leaflet (initially, approximately 10(5)). When a solution containing PLC-delta flows past the bead, the enzyme adsorbs to the surface and hydrolyzes PIP2 to form the neutral lipid diacylglycerol. We observed a nonexponential decay of PIP2 on the bead with time that is consistent with a model based on the known structural properties of PLC-delta.

Gas insulated transmission line having tapered particle trapping ring

DOEpatents

Cookson, Alan H.

1982-01-01

A gas-insulated transmission line includes an outer sheath, an inner conductor, insulating supports and an insulating gas. A particle-trapping ring is secured to each insulating support, and it is comprised of a central portion and two tapered end portions. The ends of the particle trapping ring have a smaller diameter than the central portion of the ring, so as to enable the use of the particle trapping ring in a curved transmission line.

Bounds on area and charge for marginally trapped surfaces with a cosmological constant

NASA Astrophysics Data System (ADS)

Simon, Walter

2012-03-01

We sharpen the known inequalities AΛ ⩽ 4π(1 - g) (Hayward et al 1994 Phys. Rev. D 49 5080, Woolgar 1999 Class. Quantum Grav. 16 3005) and A ⩾ 4πQ2 (Dain et al 2012 Class. Quantum Grav. 29 035013) between the area A and the electric charge Q of a stable marginally outer-trapped surface (MOTS) of genus g in the presence of a cosmological constant Λ. In particular, instead of requiring stability we include the principal eigenvalue λ of the stability operator. For Λ* = Λ + λ > 0, we obtain a lower and an upper bound for Λ*A in terms of Λ*Q2, as well as the upper bound Q \\le 1/(2\\sqrt{\\Lambda ^{*}}) for the charge, which reduces to Q \\le 1/(2\\sqrt{\\Lambda }) in the stable case λ ⩾ 0. For Λ* < 0, there only remains a lower bound on A. In the spherically symmetric, static, stable case, one of our area inequalities is saturated iff the surface gravity vanishes. We also discuss implications of our inequalities for ‘jumps’ and mergers of charged MOTS.

A toy Penrose inequality and its proof

NASA Astrophysics Data System (ADS)

Bengtsson, Ingemar; Jakobsson, Emma

2016-12-01

We formulate and prove a toy version of the Penrose inequality. The formulation mimics the original Penrose inequality in which the scenario is the following: a shell of null dust collapses in Minkowski space and a marginally trapped surface forms on it. Through a series of arguments relying on established assumptions, an inequality relating the area of this surface to the total energy of the shell is formulated. Then a further reformulation turns the inequality into a statement relating the area and the outer null expansion of a class of surfaces in Minkowski space itself. The inequality has been proven to hold true in many special cases, but there is no proof in general. In the toy version here presented, an analogous inequality in (2 + 1)-dimensional anti-de Sitter space turns out to hold true.

Pioneer 10/11 data analysis of the trapped radiation experiment

NASA Technical Reports Server (NTRS)

Fillius, W.

1982-01-01

The data handling operations and the database produced by the Trapped Radiation Experiment on the NASA Pioneer 10 and 11 spacecraft are outlined. In situ measurements of trapped radiation at both Jupiter and Saturn, the extension of cosmic ray observations to the outer heliosphere, the presence of Jovian electrons in interplanetary space, analyses of the interaction between planetary satellites and the trapped radiation that engulfs them, and further investigations of the radiation enviroments of both planets are reported.

Water and Volatiles in the Outer Solar System

NASA Astrophysics Data System (ADS)

Grasset, O.; Castillo-Rogez, J.; Guillot, T.; Fletcher, L. N.; Tosi, F.

2017-10-01

Space exploration and ground-based observations have provided outstanding evidence of the diversity and the complexity of the outer solar system. This work presents our current understanding of the nature and distribution of water and water-rich materials from the water snow line to the Kuiper Belt. This synthesis is timely, since a thorough exploration of at least one object in each region of the outer solar system has now been achieved. Next steps, starting with the Juno mission now in orbit around Jupiter, will be more focused on understanding the processes at work than on describing the general characteristics of each giant planet systems. This review is organized in three parts. First, the nature and the distribution of water and volatiles in giant and intermediary planets are described from their inner core to their outer envelopes. A special focus is given to Jupiter and Saturn, which are much better understood than the two ice giants (Uranus and Neptune) thanks to the Galileo and Cassini missions. Second, the icy moons will be discussed. Space missions and ground-based observations have revealed the variety of icy surfaces in the outer system. While Europa, Enceladus, and maybe Titan present past or even active tectonic and volcanic activities, many other moons have been dead worlds for more than 3 billion years. Ice compositions found at these bodies are also complex and it is now commonly admitted that icy surfaces are never composed of pure ices. A detailed review of the distribution of non-ice materials on the surfaces and in the tenuous atmospheres of the moons is proposed, followed by a more focused discussion on the nature and the characteristics of the liquid layers trapped below the cold icy crusts that have been suggested in the icy Galilean moons, and in Enceladus, Dione, and Titan at Saturn. Finally, the recent observations collected by Dawn at Ceres and New Horizons at Pluto, as well as the state of knowledge of other transneptunian objects, are summarized, and complete this overview of the nature and distribution of ice-rich material in the outer solar system.

Electrorefining cell with parallel electrode/concentric cylinder cathode

DOEpatents

Gay, Eddie C.; Miller, William E.; Laidler, James J.

1997-01-01

A cathode-anode arrangement for use in an electrolytic cell is adapted for electrochemically refining spent nuclear fuel from a nuclear reactor and recovering purified uranium for further treatment and possible recycling as a fresh blanket or core fuel in a nuclear reactor. The arrangement includes a plurality of inner anodic dissolution baskets that are each attached to a respective support rod, are submerged in a molten lithium halide salt, and are rotationally displaced. An inner hollow cylindrical-shaped cathode is concentrically disposed about the inner anodic dissolution baskets. Concentrically disposed about the inner cathode in a spaced manner are a plurality of outer anodic dissolution baskets, while an outer hollow cylindrical-shaped is disposed about the outer anodic dissolution baskets. Uranium is transported from the anode baskets and deposited in a uniform cylindrical shape on the inner and outer cathode cylinders by rotating the anode baskets within the molten lithium halide salt. Scrapers located on each anode basket abrade and remove the spent fuel deposits on the surfaces of the inner and outer cathode cylinders, with the spent fuel falling to the bottom of the cell for removal. Cell resistance is reduced and uranium deposition rate enhanced by increasing the electrode area and reducing the anode-cathode spacing. Collection efficiency is enhanced by trapping and recovery of uranium dendrites scrapped off of the cylindrical cathodes which may be greater in number than two.

Electrorefining cell with parallel electrode/concentric cylinder cathode

DOEpatents

Gay, E.C.; Miller, W.E.; Laidler, J.J.

1997-07-22

A cathode-anode arrangement for use in an electrolytic cell is adapted for electrochemically refining spent nuclear fuel from a nuclear reactor and recovering purified uranium for further treatment and possible recycling as a fresh blanket or core fuel in a nuclear reactor. The arrangement includes a plurality of inner anodic dissolution baskets that are each attached to a respective support rod, are submerged in a molten lithium halide salt, and are rotationally displaced. An inner hollow cylindrical-shaped cathode is concentrically disposed about the inner anodic dissolution baskets. Concentrically disposed about the inner cathode in a spaced manner are a plurality of outer anodic dissolution baskets, while an outer hollow cylindrical-shaped is disposed about the outer anodic dissolution baskets. Uranium is transported from the anode baskets and deposited in a uniform cylindrical shape on the inner and outer cathode cylinders by rotating the anode baskets within the molten lithium halide salt. Scrapers located on each anode basket abrade and remove the spent fuel deposits on the surfaces of the inner and outer cathode cylinders, with the spent fuel falling to the bottom of the cell for removal. Cell resistance is reduced and uranium deposition rate enhanced by increasing the electrode area and reducing the anode-cathode spacing. Collection efficiency is enhanced by trapping and recovery of uranium dendrites scrapped off of the cylindrical cathodes which may be greater in number than two. 12 figs.

Comment on "Curvature capillary migration of microspheres" by N. Sharifi-Mood, I. B. Liu, K. J. Stebe, Soft Matter, 2015, 11, 6768.

PubMed

Würger, Alois

2016-01-14

In a recent paper, Sharifi-Mood et al. studied colloidal particles trapped at a liquid interface with opposite principal curvatures c1 = -c2. In the theory part, they claim that the trapping energy vanishes at second order in Δc = c1 - c2, which would invalidate our previous result [Phys. Rev. E: Stat., Nonlinear, Soft Matter Phys., 2006, 74, 041402]. Here we show that this claim arises from an improper treatment of the outer boundary condition on the deformation field. For both pinned and moving contact lines, we find that the outer boundary is irrelevant, which confirms our previous work. More generally, we show that the trapping energy is determined by the deformation close to the particle and does not depend on the far-field.

Particle trap for compressed gas insulated transmission systems

DOEpatents

Cookson, A.H.

1984-04-26

A particle trap is provided for gas insulated transmission lines having a central high voltage conductor supported within an outer coaxial conductive sheath by a dielectric support member. A cavity between the inner conductor and outer sheath is filled with a dielectric insulating gas. A cone-like particle deflector, mounted to the inner conductor, deflects moving particles away from the support member, to radially outer portions of the cavity. A conductive shield is disposed adjacent the outer sheath to form a field-free region in radially outer portions of the cavity, between the shield and the sheath. Particles traveling along the cavity are deflected by the cone-like deflector into the field-free region where they are held immobile. In a vertical embodiment, particles enter the field-free region through an upper end of a gap formed between shield and sheath members. In a horizontal embodiment, the deflector cone has a base which is terminated radially internally of the shield. Apertures in the shield located adjacent the deflector allow passage of deflected particles into the field-free region. The dielectric support member is thereby protected from contaminating particles that may otherwise come to rest thereon.

Particle trap for compressed gas insulated transmission systems

DOEpatents

Cookson, Alan H.

1985-01-01

A particle trap is provided for gas insulated transmission lines having a central high voltage conductor supported within an outer coaxial conductive sheath by a dielectric support member. A cavity between the inner conductor and outer sheath is filled with a dielectric insulating gas. A cone-like particle deflector, mounted to the inner conductor, deflects moving particles away from the support member, to radially outer portions of the cavity. A conductive shield is disposed adjacent the outer sheath to form a field-free region in radially outer portions of the cavity, between the shield and the sheath. Particles traveling along the cavity are deflected by the cone-like deflector into the field-free region where they are held immobile. In a vertical embodiment, particles enter the field-free region through an upper end of a gap formed between shield and sheath members. In a horizontal embodiment, the deflector cone has a base which is terminated radially internally of the shield. Apertures in the shield located adjacent the deflector allow passage of deflected particles into the field-free region. The dielectric support member is thereby protected from contaminating particles that may otherwise come to rest thereon.

Component with inspection-facilitating features

DOEpatents

Marra, John J; Zombo, Paul J

2014-02-11

A turbine airfoil can be formed with features to facilitate measurement of its wall thickness. An outer wall of the airfoil can include an outer surface and an inner surface. The outer surface of the airfoil can have an outer inspection target surface, and the inner surface of the airfoil can have an inner inspection target surface. The inner and outer target surfaces can define substantially flat regions in surfaces that are otherwise highly contoured. The inner and outer inspection target surfaces can be substantially aligned with each other. The inner and outer target surfaces can be substantially parallel to each other. As a result of these arrangements, a highly accurate measurement of wall thickness can be obtained. In one embodiment, the outer inspection target surface can be defined by an innermost surface of a groove formed in the outer surface of the outer wall of the airfoil.

50 CFR 229.32 - Atlantic large whale take reduction plan regulations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... South Channel Restricted Trap/Pot Area where it overlaps with Lobster Management Area (LMA) 2 and the Outer Cape LMA (as defined in the American Lobster Fishery regulations in 50 CFR 697.18), and the... defined in the American Lobster Fishery regulations in 50 CFR 697.18), and the Offshore Trap/Pot Waters...

50 CFR 229.32 - Atlantic large whale take reduction plan regulations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... South Channel Restricted Trap/Pot Area where it overlaps with Lobster Management Area (LMA) 2 and the... Trap/Pot Area overlaps with Lobster Management Area (LMA) 2 and the Outer Cape LMA (as defined in the... Offshore Management Area 3 (including the area known as the Area 2/3 Overlap and Area 3/5 Overlap as...

Optical trapping forces of a focused azimuthally polarized Bessel-Gaussian beam on a double-layered sphere

NASA Astrophysics Data System (ADS)

Wu, F. P.; Zhang, B.; Liu, Z. L.; Tang, Y.; Zhang, N.

2017-12-01

We calculate the trapping forces exerted by a highly focused Bessel-Gaussian beam on a double-layered sphere by means of vector diffraction integral, T-matrix method and Maxwell stress tensor integral. The Bessel-Gaussian beam is azimuthally polarized. Numerical results predicate that the double-layered sphere with air core can be stably trapped in three-dimensions. The trapping forces and efficiencies are dependent on the refraction index and size of the inner core. The trapping efficiency can be optimized by choosing the refraction indices of the inner core and outer layer. Our computational method can be easily modified for other laser beams and particles with arbitrary geometries and multilayers.

ULTRAVIOLET PHOTON-INDUCED SYNTHESIS AND TRAPPING OF H{sub 2}O{sub 2} AND O{sub 3} IN POROUS WATER ICE FILMS IN THE PRESENCE OF AMBIENT O{sub 2}: IMPLICATIONS FOR EXTRATERRESTRIAL ICE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, J.; Raut, U.; Kim, J.-H.

2011-09-01

The mass uptake of ambient oxygen in nanoporous ice is enhanced by irradiation with 193 nm photons, due to conversion of O{sub 2} into H{sub 2}O{sub 2} and O{sub 3}, with an efficiency that increases with decreasing temperature. These findings show a new way to form H{sub 2}O{sub 2} and O{sub 3} on icy surfaces in the outer solar system at depths much larger than are accessible by typical ionizing radiation, with possible astrobiological implications.

Triton's Geyser-like Plumes

NASA Astrophysics Data System (ADS)

Brown, Robert H.; Soderblom, Laurence A.

In August of 1989, while flying by Neptune's largest satellite Triton, Voyager 2 made another of its stunning discoveries in its epic journey through the outer solar system. First seen by one of us (LAS) and Tammy Becker (also of the USGS), after stereoscopic examination of a group of images taken very near Voyager's closest approach to the satellite, were at least two, geyser-like plumes spewing almost perfectly vertical columns of material 1-km across roughly 8-km high into Triton's atmosphere; there the columns were sheared by stratospheric winds into 100-km-long, dark clouds thought to composed of condensed nitrogen mixed with organic particles. Triton's plumes may be the most unique of all the manifestations of geologic activity on satellites in the outer solar system in that their energy source may be sunlight trapped below Triton's surface in a so-called "solid-state greenhouse". This talk will focus on the physical characteristics of those plumes, and on the various mechanisms proposed to explain their presence and apparent persistence on Triton.

Modeling Surface Processes Occurring on Moons of the Outer Solar System

NASA Astrophysics Data System (ADS)

Umurhan, O. M.; White, O. L.; Moore, J. M.; Howard, A. D.; Schenk, P.

2016-12-01

A variety of processes, some with familiar terrestrial analogs, are known to take place on moon surfaces in the outer solar system. In this talk, we discuss the observed features of mass wasting and surface transport seen on both Jupiter's moon Calisto and one of Saturn's Trojan moons Helene. We provide a number of numerical models using upgraded version of MARSSIM in support of several hypotheses suggested on behalf of the observations made regarding these objects. Calisto exhibits rolling plains of low albedo materials surrounding relatively high jutting peaks harboring high albedo deposits. Our modeling supports the interpretation that Calisto's surface is a record of erosion driven by the sublimation of CO2 and H2O contained in the bedrock. Both solar insolation and surface re-radiation drives the sublimation leaving behind debris which we interpret to be the observed darkened regolith and, further, the high albedo peaks are water ice deposits on surface cold traps. On the other hand, the 45 km scale Helene, being a milligravity environment, exhibits mysterious looking streaks and grooves of very high albedo materials extending for several kilometers with a down-sloping grade of 7o-9o. Helene's cratered terrain also shows evidence of narrowed septa. The observed surface features suggest some type of advective processes are at play in this system. Our modeling lends support to the suggestion that Helene's surface materials behave as a Bingham plastic material - our flow modeling with such rheologies can reproduce the observed pattern of streakiness depending upon the smoothness of the underlying bedrock; the overall gradients observed; and the narrowed septa of inter-crater regions.

Enhanced photon traps for Hyper-Kamiokande

NASA Astrophysics Data System (ADS)

Rott, Carsten; In, Seongjin; Retière, Fabrice; Gumplinger, Peter

2017-11-01

Hyper-Kamiokande, the next generation large water Cherenkov detector in Japan, is planning to use approximately 80,000 20-inch photomultiplier tubes (PMTs). They are one of the major cost factors of the experiment. We propose a novel enhanced photon trap design based on a smaller and more economical PMT in combination with wavelength shifters, dichroic mirrors, and broadband mirrors. GEANT4 is utilized to obtain photon collection efficiencies and timing resolution of the photon traps. We compare the performance of different trap configurations and sizes. Our simulations indicate an enhanced photon trap with a 12-inch PMT can match a 20-inch PMT's collection efficiency, however at a cost of reduced timing resolution. The photon trap might be suitable as detection module for the outer detector with large photo coverage area.

OUTER RADIATION BELT AND AURORAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gorchakov, E.V.

1961-01-01

Data obtained from Sputnik IH were used to determine the high-latitude boundary of the outer radiation belt and to interpret the nature of auroras. At the heights at which the auroras were observed, the outer boundary of the belt (69 deg north geomagnetic latitude) practically coincides with the auroral zone maximum (70 deg north geomagnetic latitude), while the maximum intensity of the outer belt near the earth lies at about 55 deg north geomagnetic latitude, i.e., at latitudes 15 deg below the auroral maximum. Consequently, auroras near the zone of maximum cannot be caused by the penetration into the atmospheremore » of electrons from the outer belt with energies on the order of 0.1 Mev (the mean energy of electrons in the outer belt). Other investigators have reported the detection of lowenergy streams at 55,000 to 75,000 km from the center of the earth in the equatorial plane. Moving toward the surface of the earth along the force lines of the magnetic field, electron streams of this type will reach the earth precisely in the region of the auroral zone maximum. It is considered possible that the electron streams are trapped at these distances from the earth and are at least partially responsible for auroras in the region of maximum. The existence of two maxima in the latitudinal distribution of auroral frequency, which attests to differert mechanisms of aurora formation, favors this hypothesis. In the region of the basic auroral maximum (70 deg north geomagnetic latitude) the auroras are the result of the invasion of belt particles, while in the region of the additional maximum (about 80 deg north geomagnetic latitude) they are caused by the direct penetration of corpuscular streams into the atmosphere. (OTS)« less

Trap seal for open circuit liquid cooled turbines

DOEpatents

Grondahl, Clayton M.; Germain, Malcolm R.

1980-01-01

An improved trap seal for open circuit liquid cooled turbines is disclosed. The trap seal of the present invention includes an annular recess formed in the supply conduit of cooling channels formed in the airfoil of the turbine buckets. A cylindrical insert is located in the annular recesses and has a plurality of axial grooves formed along the outer periphery thereof and a central recess formed in one end thereof. The axial grooves and central recess formed in the cylindrical insert cooperate with the annular recess to define a plurality of S-shaped trap seals which permit the passage of liquid coolant but prohibit passage of gaseous coolant.

In situ plasma removal of surface contaminants from ion trap electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haltli, Raymond A.

2015-05-01

In this thesis, the construction and implementation of an in situ plasma discharge designed to remove surface contaminants from electrodes in an ion trapping experimental system is presented with results. In recent years, many advances have been made in using ion traps for quantum information processing. All of the criteria defined by DiVincenzo for using ion traps for implementing a quantum computer have been individually demonstrated, and in particular surface traps provide a scalable platform for ions. In order to be used for quantum algorithms, trapped ions need to be cooled to their motional (quantum mechanical) ground state. One ofmore » the hurdles in integrating surface ion traps for a quantum computer is minimizing electric field noise, which causes the ion to heat out of its motional ground state and which increases with smaller ion-to-electrode distances realized with surface traps. Surface contamination of trap electrodes is speculated to be the primary source of electric field noise. The main goal achieved by this work was to implement an in situ surface cleaning solution for surface electrode ion traps, which would not modify the ion trap electrode surface metal. Care was taken in applying the RF power in order to localize a plasma near the trap electrodes. A method for characterizing the energy of the plasma ions arriving at the ion trap surface is presented and results for plasma ion energies are shown. Finally, a method for quantifying the effectiveness of plasma cleaning of trap electrodes, using the surface analysis technique of X-ray photoelectron spectroscopy for measuring the amount and kind of surface contaminants, is described. A significant advantage of the trap electrode surface cleaning method presented here is the minimal changes necessary for implementation on a working ion trap experimental system.« less

Compositional maps of Saturn's moon Phoebe from imaging spectroscopy

USGS Publications Warehouse

Clark, R.N.; Brown, R.H.; Jaumann, R.; Cruikshank, D.P.; Nelson, R.M.; Buratti, B.J.; McCord, T.B.; Lunine, J.; Baines, K.H.; Bellucci, G.; Bibring, J.-P.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Formisano, V.; Langevin, Y.; Matson, D.L.; Mennella, V.; Nicholson, P.D.; Sicardy, B.; Sotin, Christophe; Hoefen, T.M.; Curchin, J.M.; Hansen, G.; Hibbits, K.; Matz, K.-D.

2005-01-01

The origin of Phoebe, which is the outermost large satellite of Saturn, is of particular interest because its inclined, retrograde orbit suggests that it was gravitationally captured by Saturn, having accreted outside the region of the solar nebula in which Saturn formed. By contrast, Saturn's regular satellites (with prograde, low-inclination, circular orbits) probably accreted within the sub-nebula in which Saturn itself formed. Here we report imaging spectroscopy of Phoebe resulting from the Cassini-Huygens spacecraft encounter on 11 June 2004. We mapped ferrous-iron-bearing minerals, bound water, trapped CO2, probable phyllosilicates, organics, nitriles and cyanide compounds. Detection of these compounds on Phoebe makes it one of the most compositionally diverse objects yet observed in our Solar System. It is likely that Phoebe's surface contains primitive materials from the outer Solar System, indicating a surface of cometary origin.

MOMA and other next-generation ion trap mass spectrometers for planetary exploration

NASA Astrophysics Data System (ADS)

Arevalo, R. D., Jr.; Brinckerhoff, W. B.; Getty, S.; Mahaffy, P. R.; van Amerom, F. H. W.; Danell, R.; Pinnick, V. T.; Li, X.; Grubisic, A.; Southard, A. E.; Hovmand, L.; Cottin, H.; Makarov, A.

2016-12-01

Since the 1970's, quadrupole mass spectrometer (QMS) systems have served as low-risk, cost-efficient means to explore the inner and outer reaches of the solar system. These legacy instruments have interrogated the compositions of the lunar exosphere (LADEE), surface materials on Mars (MSL), and the atmospheres of Venus (Pioneer Venus), Mars (MAVEN) and outer planets (Galileo and Cassini-Huygens). However, the in situ detection of organic compounds on Mars and Titan, coupled with ground-based measurements of amino acids in meteorites and a variety of organics in comets, has underlined the importance of molecular disambiguation in the characterization of high-priority planetary environments. The Mars Organic Molecule Analyzer (MOMA) flight instrument, centered on a linear ion trap, enables the in situ detection of volatile and non-volatile organics, but also the characterization of molecular structures through SWIFT ion isolation/excitation and tandem mass spectrometry (MSn). Like the SAM instrument on MSL, the MOMA investigation also includes a gas chromatograph (GC), thereby enabling the chemical separation of potential isobaric interferences based on retention times. The Linear Ion Trap Mass Spectrometer (LITMS; PI: William Brinckerhoff), developed to TRL 6 via the ROSES MatISSE Program, augments the core MOMA design and adds: expanded mass range (from 20 - 2000 Da); high-temperature evolved gas analysis (up to 1300°C); and, dual polarity detector assemblies (supporting the measurement of negative ions). The LITMS instrument will be tested in the field in 2017 through the Atacama Rover Astrobiology Drilling Studies (ARADS; PI: Brian Glass) ROSES PSTAR award. Following on these advancements, the Advanced Resolution Organic Molecule Analyzer (AROMA; PI: Ricardo Arevalo Jr.), supported through the ROSES PICASSO Program, combines a highly capable MOMA/LITMS-like linear ion trap and the ultrahigh resolution CosmOrbitrap mass analyzer developed by a consortium of five French laboratories. Phase I of this project has seen the development of a dedicated testbed that enables performance characterization of an Orbitrap analyzer as a function of compromised environmental conditions, simulating the reduced resources expected for planetary missions to small bodies and/or cryogenic worlds.

Frostbite

MedlinePlus

... trapped between the layers of clothing acts as insulation against the cold. Wear windproof and waterproof outer ... liners that fit well, wick moisture and provide insulation. You might also try hand and foot warmers. ...

Space Weathering on Icy Satellites in the Outer Solar System

NASA Technical Reports Server (NTRS)

Clark, R. N.; Perlman, Z.; Pearson, N.; Cruikshank, D. P.

2014-01-01

Space weathering produces well-known optical effects in silicate minerals in the inner Solar System, for example, on the Moon. Space weathering from solar wind and UV (ultraviolet radiation) is expected to be significantly weaker in the outer Solar System simply because intensities are low. However, cosmic rays and micrometeoroid bombardment would be similar to first order. That, combined with the much higher volatility of icy surfaces means there is the potential for space weathering on icy outer Solar System surfaces to show optical effects. The Cassini spacecraft orbiting Saturn is providing evidence for space weathering on icy bodies. The Cassini Visible and Infrared Mapping Spectrometer (VIMS) instrument has spatially mapped satellite surfaces and the rings from 0.35-5 microns and the Ultraviolet Imaging Spectrograph (UVIS) instrument from 0.1 to 0.2 microns. These data have sampled a complex mixing space between H2O ice and non-ice components and they show some common spectral properties. Similarly, spectra of the icy Galilean satellites and satellites in the Uranian system have some commonality in spectral properties with those in the Saturn system. The UV absorber is spectrally similar on many surfaces. VIMS has identified CO2, H2 and trace organics in varying abundances on Saturn's satellites. We postulate that through the spatial relationships of some of these compounds that they are created and destroyed through space weathering effects. For example, the trapped H2 and CO2 observed by VIMS in regions with high concentrations of dark material may in part be space weathering products from the destruction of H2O and organic molecules. The dark material, particularly on Iapetus which has the highest concentration in the Saturn system, is well matched by space-weathered silicates in the .4 to 2.6 micron range, and the spectral shapes closely match those of the most mature lunar soils, another indicator of space weathered material.

Rigidity of outermost MOTS: the initial data version

NASA Astrophysics Data System (ADS)

Galloway, Gregory J.

2018-03-01

In the paper Commun Anal Geom 16(1):217-229, 2008, a rigidity result was obtained for outermost marginally outer trapped surfaces (MOTSs) that do not admit metrics of positive scalar curvature. This allowed one to treat the "borderline case" in the author's work with R. Schoen concerning the topology of higher dimensional black holes (Commun Math Phys 266(2):571-576, 2006). The proof of this rigidity result involved bending the initial data manifold in the vicinity of the MOTS within the ambient spacetime. In this note we show how to circumvent this step, and thereby obtain a pure initial data version of this rigidity result and its consequence concerning the topology of black holes.

Methodology and Data Sources for Assessing Extreme Charging Events within the Earth's Magnetosphere

NASA Astrophysics Data System (ADS)

Parker, L. N.; Minow, J. I.; Talaat, E. R.

2016-12-01

Spacecraft surface and internal charging is a potential threat to space technologies because electrostatic discharges on, or within, charged spacecraft materials can result in a number of adverse impacts to spacecraft systems. The Space Weather Action Plan (SWAP) ionizing radiation benchmark team recognized that spacecraft charging will need to be considered to complete the ionizing radiation benchmarks in order to evaluate the threat of charging to critical space infrastructure operating within the near-Earth ionizing radiation environments. However, the team chose to defer work on the lower energy charging environments and focus the initial benchmark efforts on the higher energy galactic cosmic ray, solar energetic particle, and trapped radiation belt particle environments of concern for radiation dose and single event effects in humans and hardware. Therefore, an initial set of 1 in 100 year spacecraft charging environment benchmarks remains to be defined to meet the SWAP goals. This presentation will discuss the available data sources and a methodology to assess the 1 in 100 year extreme space weather events that drive surface and internal charging threats to spacecraft. Environments to be considered are the hot plasmas in the outer magnetosphere during geomagnetic storms, relativistic electrons in the outer radiation belt, and energetic auroral electrons in low Earth orbit at high latitudes.

Testing for Dark Matter Trapped in the Solar System

NASA Technical Reports Server (NTRS)

Krisher, Timothy P.

1996-01-01

We consider the possibility of dark matter trapped in the solar system in bound solar orbits. If there exist mechanisms for dissipating excess kinetic energy by an amount sufficient for generating bound solar orbits, then trapping of galactic dark matter might have taken place during formation of the solar system, or could be an ongoing process. Possible locations for acumulation of trapped dark matter are orbital resonances with the planets or regions in the outer solar system. It is posible to test for the presence of unseen matter by detecting its gravitational effects. Current results for dynamical limits obtained from analyses of planetary ephemeris data and spacecraft tracking data are presented. Possible future improvements are discussed.

Time variations of magnetospheric intensities of outer zone protons, alpha particles and ions (Z greater than or equal to 2). Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Randall, B. A.

1973-01-01

A comprehensive study of the temporal behavior of trapped protons, alpha particles and ions (Z 2) in outer zone of the earth's magnetosphere has been made. These observations were made by the Injun V satellite during the first 21 months of operation, August 1968 to May 1970. Rapid increases in the observed number of particles followed by slower exponential decay characterize the data. Comparisons are made with the temporal behavior of interplanetary particles of the same energy observed by Explorer 35. Increases in the trapped fluxes generally correspond to enhanced interplanetary activity. The energy spectra of protons and alpha particles at L = 3 have similar shapes when compared on an energy per charge basis while the respective polar cap spectra have similar shape on an energy per nucleon basis. Apparent inward trans-L motion of energetic protons is observed. These particles are diffused inward by a process involving fluctuating electric fields. The loss of trapped low altitude protons, alpha particles and ions (Z 2) is controlled by coulombic energy loss in the atmosphere.

Long-lived Eccentric modes in Protoplanetary Disks

NASA Astrophysics Data System (ADS)

Lee, Wing-Kit; Dempsey, Adam M.; Lithwick, Yoram

2018-04-01

A theory is developed to understand global eccentric modes that are slowly precessing in protoplanetary disks. Using the typical self-similar density profiles, we found that these modes are trapped in the disk and are not sensitive to the uncertain boundary condition at the disk edge. This is contrary to common wisdom that the modes can only exist in disks with very sharp outer edge. Because of their discrete spectrum, once excited, a perturbed disk can stay eccentric for a long time until the mode is viscously damped. The physics behind the mode trapping depends ultimately on the relative importance of gas pressure and self-gravity, which is characterized by g = 1/ (Q h), where h is the disk aspect ratio and Q is the Toomre stability parameter. A very low mass disk (g ≪ 1) is pressure-dominated and supports pressure modes, in which the eccentricity is highest at the disk edge. The modes are trapped by a turning point due to the density drop in the outer disk. For a more massive disk with g of order of unity (Q~1/h~10-100), prograde modes are supported. Unlike the pressure modes, these modes are trapped by Q-barriers and result in a bump in the radial eccentricity profile. As the mode trapping is a generic phenomenon for typical disk profiles, the free linear eccentric modes are likely to be present in protoplanetary disks with a wide range of disk mass.

Turbine airfoil with outer wall thickness indicators

DOEpatents

Marra, John J; James, Allister W; Merrill, Gary B

2013-08-06

A turbine airfoil usable in a turbine engine and including a depth indicator for determining outer wall blade thickness. The airfoil may include an outer wall having a plurality of grooves in the outer surface of the outer wall. The grooves may have a depth that represents a desired outer surface and wall thickness of the outer wall. The material forming an outer surface of the outer wall may be removed to be flush with an innermost point in each groove, thereby reducing the wall thickness and increasing efficiency. The plurality of grooves may be positioned in a radially outer region of the airfoil proximate to the tip.

Segmented trapped vortex cavity

NASA Technical Reports Server (NTRS)

Grammel, Jr., Leonard Paul (Inventor); Pennekamp, David Lance (Inventor); Winslow, Jr., Ralph Henry (Inventor)

2010-01-01

An annular trapped vortex cavity assembly segment comprising includes a cavity forward wall, a cavity aft wall, and a cavity radially outer wall there between defining a cavity segment therein. A cavity opening extends between the forward and aft walls at a radially inner end of the assembly segment. Radially spaced apart pluralities of air injection first and second holes extend through the forward and aft walls respectively. The segment may include first and second expansion joint features at distal first and second ends respectively of the segment. The segment may include a forward subcomponent including the cavity forward wall attached to an aft subcomponent including the cavity aft wall. The forward and aft subcomponents include forward and aft portions of the cavity radially outer wall respectively. A ring of the segments may be circumferentially disposed about an axis to form an annular segmented vortex cavity assembly.

Improving detection tools for emerald ash borer (Coleoptera: Buprestidae): comparison of multifunnel traps, prism traps, and lure types at varying population densities.

PubMed

Crook, Damon J; Francese, Joseph A; Rietz, Michael L; Lance, David R; Hull-Sanders, Helen M; Mastro, Victor C; Silk, Peter J; Ryall, Krista L

2014-08-01

The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a serious invasive pest of North American ash (Fraxinus spp.) that has caused devastating mortality since it was first identified in North America in 2002. In 2012, we conducted field trapping assays that tested the efficacy of purple prism and fluon-coated green multifunnel (Lindgren funnel) traps. Traps were baited with combinations of several lures that were previously shown to be attractive to A. planipennis: manuka oil--a sesquiterpene-rich oil, (3Z)-hexenol--a green leaf volatile, or (3Z)-dodecen-12-olide [= (3Z)-lactone], a sex pheromone. Eighty-nine blocks (trap lines) were tested throughout nine states along the outer edges of the currently known A. planipennis infestation in North America. Trap catch was highest on fluon-coated green multifunnel traps, and trap detections at sites with low A. planipennis population density ranged from 72 to 76% for all trap and lure types tested. (3Z)-hexenol and (3Z)-lactone baited traps functioned as well as (3Z)-hexenol and manuka oil-baited traps. Independent of the lure used, detection rates on green fluon-coated multifunnel traps were comparable with glued purple prism traps in areas with low A. planipennis population densities.

The Molecular Volcano Revisited: Determination of Crack Propagation and Distribution During the Crystallization of Nanoscale Amorphous Solid Water Films.

DOE Office of Scientific and Technical Information (OSTI.GOV)

May, Robert A.; Smith, R. Scott; Kay, Bruce D.

2012-02-02

Temperature programmed desorption (TPD) is utilized to determine the length distribution of cracks formed through amorphous solid water (ASW) during crystallization. This distribution is determined by monitoring how the thickness of an ASW overlayer alters desorption of an underlayer of O2. As deposited the ASW overlayer prevents desorption of O2. During crystallization, cracks form through the ASW overlayer and open a path to vacuum which allows O2 to escape in a rapid episodic release known as the 'molecular volcano'. Sufficiently thick ASW overlayers further trap O2 resulting in a second O2 desorption peak commensurate with desorption of the last ofmore » the ASW overlayer. The evolution of this trapping peak with overlayer thickness is the basis for determining the distribution of crystallization induced cracks through the ASW. Reflection adsorption infrared spectroscopy (RAIRS) and TPD of multicomponent parfait structures of ASW, O2 and Kr indicate that a preponderance of these cracks propagate down from the outer surface of the ASW.« less

Optoelectronically probing the density of nanowire surface trap states to the single state limit

NASA Astrophysics Data System (ADS)

Dan, Yaping

2015-02-01

Surface trap states play a dominant role in the optoelectronic properties of nanoscale devices. Understanding the surface trap states allows us to properly engineer the device surfaces for better performance. But characterization of surface trap states at nanoscale has been a formidable challenge using the traditional capacitive techniques. Here, we demonstrate a simple but powerful optoelectronic method to probe the density of nanowire surface trap states to the single state limit. In this method, we choose to tune the quasi-Fermi level across the bandgap of a silicon nanowire photoconductor, allowing for capture and emission of photogenerated charge carriers by surface trap states. The experimental data show that the energy density of nanowire surface trap states is in a range from 109 cm-2/eV at deep levels to 1012 cm-2/eV near the conduction band edge. This optoelectronic method allows us to conveniently probe trap states of ultra-scaled nano/quantum devices at extremely high precision.

Swirling structure for mixing two concentric fluid flows at nozzle outlet

DOEpatents

Mensink, Daniel L.

1993-01-01

A nozzle device for causing two fluids to mix together. In particular, a spray nozzle comprise two hollow, concentric housings, an inner housing and an outer housing. The inner housing has a channel formed therethrough for a first fluid. Its outer surface cooperates with the interior surface of the outer housing to define the second channel for a second fluid. The outer surface of the inner housing and the inner surface of the outer housing each carry a plurality of vanes that interleave but do not touch, each vane of one housing being between two vanes of the other housing. The vanes are curved and the inner surface of the outer housing and the outer surface of the inner housing converge to narrow the second channel. The shape of second channel results in a swirling, accelerating second fluid that will impact the first fluid just past the end of the nozzle where mixing will take place.

Contact between traps and surfaces during contact sampling of explosives in security settings.

PubMed

Chaffee-Cipich, Michelle N; Hoss, Darby J; Sweat, Melissa L; Beaudoin, Stephen P

2016-03-01

Realistic descriptions of interfacial contact between rough, deformable surfaces under load are difficult to obtain; however, this contact is of great import in a wide range of applications. Here, we detail, through experiment and computational simulation, the interfacial contact between four common traps and five commonly investigated surfaces encountered in explosives detection applications associated with airport security. The Young's modulus and hardness of four traps and seven substrates were measured using nanoindentation. These properties determine how deformation occurs when traps are applied for contact sampling of explosives. The nanoindentation data were analyzed using the Oliver-Pharr method, and an indenter area function was created using silicon and gold as the reference materials. The Young's moduli of the traps ranged from 0.2 to 8 GPa, while those of the surfaces ranged from 0.5 to 4 GPa. The hardness values of the traps ranged from 0.005 to 0.22 GPa, while those of the surfaces ranged from 0.02 to 0.2 GPa. For each of 20 scenarios (4 traps, 5 surfaces), six contact simulations were performed. In these contact simulations, the Greenwood-Willliamson microcontact model was used to represent the behavior of the asperities on the traps, while the Timoshenko Beam model was used to describe the macroscopic behavior of the bulk trap materials spanning the space between asperities. This combination of feature- and trap-scale modeling provides a more realistic description of the interfacial contact than either model applied individually. The calculated distributions of separation distances between the traps and surfaces when the traps were contacted with the surfaces under a normal load were compared to estimate the relative effectiveness of the traps at interrogating the topography of the surfaces. This method is proposed as a tool to guide the development of trap materials for surface sampling and surface cleaning applications. Copyright © 2016. Published by Elsevier Ireland Ltd.

Attachment device for an inflatable protective cushion

DOEpatents

Nelsen, J.M.; Luna, D.A.; Gwinn, K.W.

1997-11-18

An inflatable cushion assembly for use with an inflator comprises an inflatable cushion having an inner surface, outer surface, and at least one protrusion extending from one of the inner or outer surfaces. The inflatable cushion defines an opening between the inner surface and the outer surface for receiving the inflator. An attachment member contacts the one of the inner or outer surfaces adjacent the opening and includes a groove for receiving the protrusion, the attachment member securing the inflator within the opening. 22 figs.

Attachment device for an inflatable protective cushion

DOEpatents

Nelsen, J.M.; Luna, D.A.; Gwinn, K.W.

1998-12-08

An inflatable cushion assembly for use with an inflator comprises an inflatable cushion having an inner surface, outer surface, and at least one protrusion extending from one of the inner or outer surfaces. The inflatable cushion defines an opening between the inner surface and the outer surface for receiving the inflator. An attachment member contacts the one of the inner or outer surfaces adjacent the opening and includes a groove for receiving the protrusion, the attachment member securing the inflator within the opening. 22 figs.

Repeated sharp flux dropouts observed at 6.6 earth radii during a geomagnetic storm

NASA Technical Reports Server (NTRS)

Su, S.-Y.; Fritz, T. A.; Konradi, A.

1976-01-01

A number of repeated rapid flux dropouts have been observed at 6.6 earth radii by the low-energy proton detectors on board the ATS 6 satellite during the July 4-6, 1974, geomagnetic storm period. These rapid flux changes are caused by the fact that the outer boundary of the trapped radiation region moves back and forth past the satellite. Although a tilting field line configuration can cause the boundary to pass the satellite, as has frequently been reported in the literature, the boundary is shown to be distorted by a large surface wave traveling eastward around the earth. The maximum velocity of the wave was observed to be about 40 km/s.

Bounds on dark matter in solar orbit

NASA Technical Reports Server (NTRS)

Anderson, John D.; Lau, Eunice L.; Taylor, Anthony H.; Dicus, Duane A.; Teplitz, Doris C.

1989-01-01

The possibility is considered that a spherical distribution of dark matter (DM), matter not visible with current instruments, is trapped in the sun's gravitational field. Bounds are placed from the motion of Uranus and Neptune, on the amount of DM that could be so trapped within the radius of those planets' orbits, as follows: from the Voyager 2, Uranus-flyby data new, more accurate ephemeris values are generated. Trapped DM mass is bounded by noting that such a distribution would increase the effective mass of the sun as seen by the outer planets and by using the new ephemeris values to bound such an increase.

Capturing self-propelled particles in a moving microwedge

NASA Astrophysics Data System (ADS)

Kaiser, A.; Popowa, K.; Wensink, H. H.; Löwen, H.

2013-08-01

Catching fish with a fishing net is typically done either by dragging a fishing net through quiescent water or by placing a stationary basket trap into a stream. We transfer these general concepts to micron-sized self-motile particles moving in a solvent at low Reynolds number and study their collective trapping behavior by means of computer simulations of a two-dimensional system of self-propelled rods. A chevron-shaped obstacle is dragged through the active suspension with a constant speed v and acts as a trapping “net.” Three trapping states can be identified corresponding to no trapping, partial trapping, and complete trapping and their relative stability is studied as a function of the apex angle of the wedge, the swimmer density, and the drag speed v. When the net is dragged along the inner wedge, complete trapping is facilitated and a partially trapped state changes into a complete trapping state if the drag speed exceeds a certain value. Reversing the drag direction leads to a reentrant transition from no trapping to complete trapping and then back to no trapping upon increasing the drag speed along the outer wedge contour. The transition to complete trapping is marked by a templated self-assembly of rods forming polar smectic structures anchored onto the inner contour of the wedge. Our predictions can be verified in experiments of artificial or microbial swimmers confined in microfluidic trapping devices.

Capturing self-propelled particles in a moving microwedge.

PubMed

Kaiser, A; Popowa, K; Wensink, H H; Löwen, H

2013-08-01

Catching fish with a fishing net is typically done either by dragging a fishing net through quiescent water or by placing a stationary basket trap into a stream. We transfer these general concepts to micron-sized self-motile particles moving in a solvent at low Reynolds number and study their collective trapping behavior by means of computer simulations of a two-dimensional system of self-propelled rods. A chevron-shaped obstacle is dragged through the active suspension with a constant speed v and acts as a trapping "net." Three trapping states can be identified corresponding to no trapping, partial trapping, and complete trapping and their relative stability is studied as a function of the apex angle of the wedge, the swimmer density, and the drag speed v. When the net is dragged along the inner wedge, complete trapping is facilitated and a partially trapped state changes into a complete trapping state if the drag speed exceeds a certain value. Reversing the drag direction leads to a reentrant transition from no trapping to complete trapping and then back to no trapping upon increasing the drag speed along the outer wedge contour. The transition to complete trapping is marked by a templated self-assembly of rods forming polar smectic structures anchored onto the inner contour of the wedge. Our predictions can be verified in experiments of artificial or microbial swimmers confined in microfluidic trapping devices.

Natural variations in the geomagnetically trapped electron population

NASA Technical Reports Server (NTRS)

Vampola, A. L.

1972-01-01

Temporal variations in the trapped natural electron flux intensities and energy spectra are discussed and demonstrated using recent satellite data. These data are intended to acquaint the space systems engineer with the types of natural variations that may be encountered during a mission and to augment the models of the electron environment currently being used in space system design and orbit selection. An understanding of the temporal variations which may be encountered should prove helpful. Some of the variations demonstrated here which are not widely known include: (1) addition of very energetic electrons to the outer zone during moderate magnetic storms: (2) addition of energetic electrons to the inner zone during major magnetic storms; (3) inversions in the outer zone electron energy spectrum during the decay phase of a storm injection event and (4) occasional formation of multiple maxima in the flux vs altitude profile of moderately energetic electrons.

Gas turbine engine combustor can with trapped vortex cavity

DOEpatents

Burrus, David Louis; Joshi, Narendra Digamber; Haynes, Joel Meier; Feitelberg, Alan S.

2005-10-04

A gas turbine engine combustor can downstream of a pre-mixer has a pre-mixer flowpath therein and circumferentially spaced apart swirling vanes disposed across the pre-mixer flowpath. A primary fuel injector is positioned for injecting fuel into the pre-mixer flowpath. A combustion chamber surrounded by an annular combustor liner disposed in supply flow communication with the pre-mixer. An annular trapped dual vortex cavity located at an upstream end of the combustor liner is defined between an annular aft wall, an annular forward wall, and a circular radially outer wall formed therebetween. A cavity opening at a radially inner end of the cavity is spaced apart from the radially outer wall. Air injection first holes are disposed through the forward wall and air injection second holes are disposed through the aft wall. Fuel injection holes are disposed through at least one of the forward and aft walls.

Uncovering the density of nanowire surface trap states hidden in the transient photoconductance.

PubMed

Xu, Qiang; Dan, Yaping

2016-09-21

The gain of nanoscale photoconductors is closely correlated with surface trap states. Mapping out the density of surface trap states in the semiconductor bandgap is crucial for engineering the performance of nanoscale photoconductors. Traditional capacitive techniques for the measurement of surface trap states are not readily applicable to nanoscale devices. Here, we demonstrate a simple technique to extract the information on the density of surface trap states hidden in the transient photoconductance that is widely observed. With this method, we found that the density of surface trap states of a single silicon nanowire is ∼10(12) cm(-2) eV(-1) around the middle of the upper half bandgap.

Design considerations for combined radiation effects facilities for twelve year outer planet spacecraft voyages

NASA Technical Reports Server (NTRS)

Miller, C. G.

1972-01-01

The design considerations influencing the choice and utility of environmental simulation methods and facilities are described, insofar as they relate to the requirements imposed on outer planet spacecraft because of radiation environments to be expected. Possible means for duplicating the radioisotope thermoelectric generator radiation environment, and for duplicating the effects of the trapped radiation belt environment are described, together with an assessment of radiation levels to be expected in the vicinity of an environmental testing chamber when in use.

Extracellular DNA-induced antimicrobial peptide resistance mechanisms in Pseudomonas aeruginosa

PubMed Central

Lewenza, Shawn

2013-01-01

Extracellular DNA (eDNA) is in the environment, bodily fluids, in the matrix of biofilms, and accumulates at infection sites. eDNA can function as a nutrient source, a universal biofilm matrix component, and an innate immune effector in eDNA traps. In biofilms, eDNA is required for attachment, aggregation, and stabilization of microcolonies. We have recently shown that eDNA can sequester divalent metal cations, which has interesting implications on antibiotic resistance. eDNA binds metal cations and thus activates the Mg2+-responsive PhoPQ and PmrAB two-component systems. In Pseudomonas aeruginosa and many other Gram-negative bacteria, the PhoPQ/PmrAB systems control various genes required for virulence and resisting killing by antimicrobial peptides (APs), including the pmr genes (PA3552–PA3559) that are responsible for the addition of aminoarabinose to lipid A. The PA4773–PA4775 genes are a second DNA-induced cluster and are required for the production of spermidine on the outer surface, which protects the outer membrane from AP treatment. Both modifications mask the negative surface charges and limit membrane damage by APs. DNA-enriched biofilms or planktonic cultures have increased antibiotic resistance phenotypes to APs and aminoglycosides. These dual antibiotic resistance and immune evasion strategies may be expressed in DNA-rich environments and contribute to long-term survival. PMID:23419933

Radio Frequency Trap for Containment of Plasmas in Antimatter Propulsion Systems Using Rotating Wall Electric Fields

NASA Technical Reports Server (NTRS)

Sims, William Herbert, III (Inventor); Martin, James Joseph (Inventor); Lewis, Raymond A. (Inventor)

2003-01-01

A containment apparatus for containing a cloud of charged particles comprises a cylindrical vacuum chamber having a longitudinal axis. Within the vacuum chamber is a containment region. A magnetic field is aligned with the longitudinal axis of the vacuum chamber. The magnetic field is time invariant and uniform in strength over the containment region. An electric field is also aligned with the longitudinal axis of the vacuum chamber and the magnetic field. The electric field is time invariant, and forms a potential well over the containment region. One or more means are disposed around the cloud of particles for inducing a rotating electric field internal to the vacuum chamber. The rotating electric field imparts energy to the charged particles within the containment region and compress the cloud of particles. The means disposed around the outer surface of the vacuum chamber for inducing a rotating electric field are four or more segments forming a segmented ring, the segments conforming to the outer surface of the vacuum chamber. Each of the segments is energized by a separate alternating voltage. The sum of the voltages imposed on each segment establishes the rotating field. When four segments form a ring, the rotating field is obtained by a signal generator applying a sinusoidal signal phase delayed by 90,180 and 270 degrees in sequence to the four segments.

Swirling structure for mixing two concentric fluid flows at nozzle outlet

DOEpatents

Mensink, D.L.

1993-07-20

A nozzle device is described for causing two fluids to mix together. In particular, a spray nozzle comprises two hollow, concentric housings, an inner housing and an outer housing. The inner housing has a channel formed therethrough for a first fluid. Its outer surface cooperates with the interior surface of the outer housing to define the second channel for a second fluid. The outer surface of the inner housing and the inner surface of the outer housing each carry a plurality of vanes that interleave but do not touch, each vane of one housing being between two vanes of the other housing. The vanes are curved and the inner surface of the outer housing and the outer surface of the inner housing converge to narrow the second channel. The shape of second channel results in a swirling, accelerating second fluid that will impact the first fluid just past the end of the nozzle where mixing will take place.

Re-Analysis of Data on the Space Radiation Environment above South-East Asia

DTIC Science & Technology

1989-11-01

the cosmic ray flux with geomagnetic latitude, and also show expected increases due to the South Atlantic Anomaly (SAA) and outer belt electrons. How...TECHNIQUES USED 8 3.1 Orbital analysis 8 3.2 Analysis of cosmic ray effects 9 3.3 Analysis of trapped particle effects 11 3.4 Geomagnetic and...magnetospheric activity 12 4 UNCERTAINTIES AND SOURCES OF ERROR 13 4.1 Orbital analysis 13 4.2 Analysis of cosmic ray effects 13 4.3 Analysis of trapped particle

Partially segmented deformable mirror

DOEpatents

Bliss, E.S.; Smith, J.R.; Salmon, J.T.; Monjes, J.A.

1991-05-21

A partially segmented deformable mirror is formed with a mirror plate having a smooth and continuous front surface and a plurality of actuators to its back surface. The back surface is divided into triangular areas which are mutually separated by grooves. The grooves are deep enough to make the plate deformable and the actuators for displacing the mirror plate in the direction normal to its surface are inserted in the grooves at the vertices of the triangular areas. Each actuator includes a transducer supported by a receptacle with outer shells having outer surfaces. The vertices have inner walls which are approximately perpendicular to the mirror surface and make planar contacts with the outer surfaces of the outer shells. The adhesive which is used on these contact surfaces tends to contract when it dries but the outer shells can bend and serve to minimize the tendency of the mirror to warp. 5 figures.

Partially segmented deformable mirror

DOEpatents

Bliss, Erlan S.; Smith, James R.; Salmon, J. Thaddeus; Monjes, Julio A.

1991-01-01

A partially segmented deformable mirror is formed with a mirror plate having a smooth and continuous front surface and a plurality of actuators to its back surface. The back surface is divided into triangular areas which are mutually separated by grooves. The grooves are deep enough to make the plate deformable and the actuators for displacing the mirror plate in the direction normal to its surface are inserted in the grooves at the vertices of the triangular areas. Each actuator includes a transducer supported by a receptacle with outer shells having outer surfaces. The vertices have inner walls which are approximately perpendicular to the mirror surface and make planar contacts with the outer surfaces of the outer shells. The adhesive which is used on these contact surfaces tends to contract when it dries but the outer shells can bend and serve to minimize the tendency of the mirror to warp.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2010-10-01

Using orbital integration and analytical arguments, we have found a new mechanism (an 'eccentricity trap') to halt type I migration of planets near the inner edge of a protoplanetary disk. Because asymmetric eccentricity damping due to disk-planet interaction on the innermost planet at the disk edge plays a crucial role in the trap, this mechanism requires continuous eccentricity excitation and hence works for a resonantly interacting convoy of planets. This trap is so strong that the edge torque exerted on the innermost planet can completely halt type I migrations of many outer planets through mutual resonant perturbations. Consequently, the convoymore » 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.« less

Surface-electrode point Paul trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Tony Hyun; Herskind, Peter F.; Chuang, Isaac L.

2010-10-15

We present a model as well as experimental results for a surface electrode radiofrequency Paul trap that has a circular electrode geometry well suited for trapping single ions and two-dimensional planar ion crystals. The trap design is compatible with microfabrication and offers a simple method by which the height of the trapped ions above the surface may be changed in situ. We demonstrate trapping of single {sup 88}Sr{sup +} ions over an ion height range of 200-1000 {mu}m for several hours under Doppler laser cooling and use these to characterize the trap, finding good agreement with our model.

MAGNETIZED ACCRETION AND DEAD ZONES IN PROTOSTELLAR DISKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dzyurkevich, Natalia; Henning, Thomas; Turner, Neal J.

The edges of magnetically dead zones in protostellar disks have been proposed as locations where density bumps may arise, trapping planetesimals and helping form planets. Magneto-rotational turbulence in magnetically active zones provides both accretion of gas on the star and transport of mass to the dead zone. We investigate the location of the magnetically active regions in a protostellar disk around a solar-type star, varying the disk temperature, surface density profile, and dust-to-gas ratio. We also consider stellar masses between 0.4 and 2 M{sub Sun }, with corresponding adjustments in the disk mass and temperature. The dead zone's size andmore » shape are found using the Elsasser number criterion with conductivities including the contributions from ions, electrons, and charged fractal dust aggregates. The charged species' abundances are found using the approach proposed by Okuzumi. The dead zone is in most cases defined by the ambipolar diffusion. In our maps, the dead zone takes a variety of shapes, including a fish tail pointing away from the star and islands located on and off the midplane. The corresponding accretion rates vary with radius, indicating locations where the surface density will increase over time, and others where it will decrease. We show that density bumps do not readily grow near the dead zone's outer edge, independently of the disk parameters and the dust properties. Instead, the accretion rate peaks at the radius where the gas-phase metals freeze out. This could lead to clearing a valley in the surface density, and to a trap for pebbles located just outside the metal freezeout line.« less

Hydration of excess electrons trapped in charge pockets on molecular surfaces

NASA Astrophysics Data System (ADS)

Jalbout, Abraham F.; Del Castillo, R.; Adamowicz, Ludwik

2007-01-01

In this work we strive to design a novel electron trap located on a molecular surface. The process of electron trapping involves hydration of the trapped electron. Previous calculations on surface electron trapping revealed that clusters of OH groups can form stable hydrogen-bonded networks on one side of a hydrocarbon surface (i.e. cyclohexane sheets), while the hydrogen atoms on the opposite side of the surface form pockets of positive charge that can attract extra negative charge. The excess electron density on such surfaces can be further stabilized by interactions with water molecules. Our calculations show that these anionic systems are stable with respect to vertical electron detachment (VDE).

Highly excited electronic image states of metallic nanorings

PubMed Central

Fey, Christian; Jabusch, Henrik; Knörzer, Johannes; Schmelcher, Peter

2017-01-01

We study electronic image states around a metallic nanoring and show that the interplay between the attractive polarization force and a repulsive centrifugal force gives rise to Rydberg-like image states trapped several nanometers away from the surface. The nanoring is modeled as a perfectly conducting isolated torus whose classical electrostatic image potential is derived analytically. The image states are computed via a two-dimensional finite-difference scheme as solutions of the effective Schrödinger equation describing the outer electron subject to this image potential. These findings demonstrate not only the existence of detached image states around nanorings but allow us also to provide general criteria on the ring geometry, i.e., the aspect ratio of the torus, that need to be fulfilled in order to support such states. PMID:28527466

Conductor load bearing roller for a gas-insulated transmission line having a corrugated outer conductor

DOEpatents

Fischer, William H.; Yoon, Kue H.

1984-04-10

A gas-insulated transmission line includes a corrugated outer conductor, an inner conductor disposed within and insulated from the outer conductor by means of support insulators and an insulating gas, and a transport device for supporting and permitting movement of the inner conductor/insulating support assembly axially along the corrugated outer conductor without radial displacement. The transport device includes two movable contacts, such as skids or rollers, supported on a common pivot lever, the pivot lever being rotatably disposed about a pivot lever axis, which pivot lever axis is in turn disposed on the periphery of a support insulator or particle trap if one is used. The movable contacts are separated axially a distance equal to the axial distance between the peaks and valleys of the corrugations of the outer conductor and separated radially a distance equal to the radial distance between the peaks and valleys of the corrugations of the outer conductor. The transport device has the pivot lever axis disposed perpendicular to the direction of travel of the inner conductor/insulating support assembly.

Architecture in outer space. [multilayer shell systems filled with gas

NASA Technical Reports Server (NTRS)

Pokrovskiy, G. I.

1974-01-01

Mulilayer thin film structures consisting of systems of shells filled with gas at some pressure are recommended for outer space structures: Large mirrors to collect light and radio waves, protection against meteoric impact and damage, and for connectors between state space stations in the form of orbital rings. It is projected that individual orbital rings will multiply and completely seal a star trapping its high temperature radiation and transforming it into low temperature infrared and short wave radio emission; this radiation energy could be utilized for technological and biological processes.

Electron beam selectively seals porous metal filters

NASA Technical Reports Server (NTRS)

Snyder, J. A.; Tulisiak, G.

1968-01-01

Electron beam welding selectively seals the outer surfaces of porous metal filters and impedances used in fluid flow systems. The outer surface can be sealed by melting a thin outer layer of the porous material with an electron beam so that the melted material fills all surface pores.

Wedge assembly for electrical transformer component spacing

DOEpatents

Baggett, Franklin E.; Cage, W. Franklin

1991-01-01

A wedge assembly that is easily inserted between two surfaces to be supported thereby, and thereafter expanded to produce a selected spacing between those surfaces. This wedge assembly has two outer members that are substantially identical except that they are mirror images of each other. Oppositely directed faces of these of these outer members are substantially parallel for the purpose of contacting the surfaces to be separated. The outer faces of these outer members that are directed toward each other are tapered so as to contact a center member having complementary tapers on both faces. A washer member is provided to contact a common end of the outer members, and a bolt member penetrates this washer and is threadably received in a receptor of the center member. As the bolt member is threaded into the center member, the center member is drawn further into the gap between the outer members and thereby separates these outer members to contact the surfaces to be separated. In the preferred embodiment, the contacting surfaces of the outer member and the center member are provided with guide elements. The wedge assembly is described for use in separating the secondary windings from the laminations of an electrical power transformer.

BBSome function is required for both the morphogenesis and maintenance of the photoreceptor outer segment

PubMed Central

Hsu, Ying; Kim, Gunhee; Zhang, Qihong; Datta, Poppy; Seo, Seongjin

2017-01-01

Genetic mutations disrupting the structure and function of primary cilia cause various inherited retinal diseases in humans. Bardet-Biedl syndrome (BBS) is a genetically heterogeneous, pleiotropic ciliopathy characterized by retinal degeneration, obesity, postaxial polydactyly, intellectual disability, and genital and renal abnormalities. To gain insight into the mechanisms of retinal degeneration in BBS, we developed a congenital knockout mouse of Bbs8, as well as conditional mouse models in which function of the BBSome (a protein complex that mediates ciliary trafficking) can be temporally inactivated or restored. We demonstrate that BBS mutant mice have defects in retinal outer segment morphogenesis. We further demonstrate that removal of Bbs8 in adult mice affects photoreceptor function and disrupts the structural integrity of the outer segment. Notably, using a mouse model in which a gene trap inhibiting Bbs8 gene expression can be removed by an inducible FLP recombinase, we show that when BBS8 is restored in immature retinas with malformed outer segments, outer segment extension can resume normally and malformed outer segment discs are displaced distally by normal outer segment structures. Over time, the retinas of the rescued mice become morphologically and functionally normal, indicating that there is a window of plasticity when initial retinal outer segment morphogenesis defects can be ameliorated. PMID:29049287

Dilution of Fluon Before Trap Surface Treatment Has No Effect on Longhorned Beetle (Coleoptera: Cerambycidae) Captures

Treesearch

Jeremy D. Allison; Elizabeth E. Graham; Therese M. Poland; Brian L. Strom

2016-01-01

Several studies have observed that trap captures of longhorned beetles (Coleoptera: Cerambycidae) can be increased by treating the surface of intercept traps with a lubricant. In addition to being expensive, these treatments can alter the spectral properties of intercept traps when applied neat. These surface treatments, particularly Fluon, are commonly used diluted as...

Radiation Belts of Antiparticles in Planetary Magnetospheres

NASA Astrophysics Data System (ADS)

Pugacheva, G. I.; Gusev, A. A.; Jayanthi, U. B.; Martin, I. M.; Spjeldvik, W. N.

2007-05-01

The Earth's radiation belts could be populated, besides with electrons and protons, also by antiparticles, such as positrons (Basilova et al., 1982) and antiprotons (pbar). Positrons are born in the decay of pions that are directly produced in nuclear reactions of trapped relativistic inner zone protons with the residual atmosphere at altitudes in the range of about 500 to 3000 km over the Earth's surface. Antiprotons are born by high energy (E > 6 GeV) cosmic rays in p+p - p+p+p+ pbar and in p+p - p+p+n+nbar reactions. The trapping and storage of these charged anti-particles in the magnetosphere result in radiation belts similar to the classical Van Allen belts of protons and electrons. We describe the mathematical techniques used for numerical simulation of the trapped positron and antiproton belt fluxes. The pion and antiproton yields were simulated on the basis of the Russian nuclear reaction computer code MSDM, a Multy Stage Dynamical Model, Monte Carlo code, (i.e., Dementyev and Sobolevsky, 1999). For estimates of positron flux there we have accounted for ionisation, bremsstrahlung, and synchrotron energy losses. The resulting numerical estimates show that the positron flux with energy >100 MeV trapped into the radiation belt at L=1.2 is of the order ~1000 m-2 s-1 sr-1, and that it is very sensitive to the shape of the trapped proton spectrum. This confined positron flux is found to be greater than that albedo, not trapped, mixed electron/positron flux of about 50 m-2 s-1 sr-1 produced by CR in the same region at the top of the geomagnetic field line at L=1.2. As we show in report, this albedo flux also consists mostly of positrons. The trapped antiproton fluxes produced by CR in the Earth's upper rarified atmosphere were calculated in the energy range from 10 MeV to several GeV. In the simulations we included a mathematic consideration of the radial diffusion process, both an inner and an outer antiproton source, losses of particles due to ionization process, annihilation, and nuclear interactions with the ambient matter. We have found that the Earth's antiproton belt possesses about 6-60 times larger antiproton fluxes compared to the galactic fluxes in interplanetary space during minimum and maximum solar activity at all energies in confinement zone. The radiation belt antiproton fluxes are spread into a wider L-shell range than its generation location around L=1.2. This is due to diffusion processes, and it demonstrates that radial diffusion as a relatively significant process for antimatter, even in the inner magnetosphere. Antimatter accumulated in the magnetospheres of solar system bodies may be of significance for space travel. It could be used as a propulsion for space missions to the outer planets and beyond. Antimatter has an energy density more than ten orders of magnitude higher than the best chemical propellants currently used in rocket systems. References: Basilova, R. N., A.A. Gusev, G.I. Pugacheva , Geom. and Aeronom. V. 22, p. 671-673, 1982.Chen, J., T. Dementyev, A.V., Sobolevsky, N.M. Radiation Measurements, 30, 553, 1999.

BPM Button Optimization to Minimize Distortion Due to Trapped Mode Heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cameron,P.; Blednyk, A.; Kosciuk, B.

2009-05-04

The outer circumference of a BPM button and the inner circumference of the button housing comprise a transmission line. This transmission line typically presents an impedance of a few tens of ohms to the beam, and couples very weakly to the 50 ohm coaxial transmission line that comprises the signal path out of the button. The modes which are consequently excited and trapped often have quality factors of several hundred, permitting resonant excitation by the beam. The thermal distortion resulting from trapped mode heating is potentially problematic for achieving the high precision beam position measurements needed to provide the sub-micronmore » beam position stability required by light source users. We present a button design that has been optimized via material selection and component geometry to minimize both the trapped mode heating and the resulting thermal distortion.« less

Gas turbine row #1 steam cooled vane

DOEpatents

Cunha, Frank J.

2000-01-01

A design for a vane segment having a closed-loop steam cooling system is provided. The vane segment comprises an outer shroud, an inner shroud and an airfoil, each component having a target surface on the inside surface of its walls. A plurality of rectangular waffle structures are provided on the target surface to enhance heat transfer between each component and cooling steam. Channel systems are provided in the shrouds to improve the flow of steam through the shrouds. Insert legs located in cavities in the airfoil are also provided. Each insert leg comprises outer channels located on a perimeter of the leg, each outer channel having an outer wall and impingement holes on the outer wall for producing impingement jets of cooling steam to contact the airfoil's target surface. Each insert leg further comprises a plurality of substantially rectangular-shaped ribs located on the outer wall and a plurality of openings located between outer channels of the leg to minimize cross flow degradation.

Real-Space Mapping of Surface Trap States in CIGSe Nanocrystals Using 4D Electron Microscopy.

PubMed

Bose, Riya; Bera, Ashok; Parida, Manas R; Adhikari, Aniruddha; Shaheen, Basamat S; Alarousu, Erkki; Sun, Jingya; Wu, Tom; Bakr, Osman M; Mohammed, Omar F

2016-07-13

Surface trap states in copper indium gallium selenide semiconductor nanocrystals (NCs), which serve as undesirable channels for nonradiative carrier recombination, remain a great challenge impeding the development of solar and optoelectronics devices based on these NCs. In order to design efficient passivation techniques to minimize these trap states, a precise knowledge about the charge carrier dynamics on the NCs surface is essential. However, selective mapping of surface traps requires capabilities beyond the reach of conventional laser spectroscopy and static electron microscopy; it can only be accessed by using a one-of-a-kind, second-generation four-dimensional scanning ultrafast electron microscope (4D S-UEM) with subpicosecond temporal and nanometer spatial resolutions. Here, we precisely map the collective surface charge carrier dynamics of copper indium gallium selenide NCs as a function of the surface trap states before and after surface passivation in real space and time using S-UEM. The time-resolved snapshots clearly demonstrate that the density of the trap states is significantly reduced after zinc sulfide (ZnS) shelling. Furthermore, the removal of trap states and elongation of carrier lifetime are confirmed by the increased photocurrent of the self-biased photodetector fabricated using the shelled NCs.

On the surface trapping parameters of polytetrafluoroethylene block

NASA Astrophysics Data System (ADS)

Zhang, Guan-Jun; Yang, Kai; Zhao, Wen-Bin; Yan, Zhang

2006-12-01

Surface flashover phenomena under high electric field are closely related to the surface characteristics of a solid insulating material between energized electrodes. Based on measuring the surface potential decaying curve of polytetrafluoroethylene (PTFE) block charged by a needle-plane corona discharge, its surface trapping parameters are calculated with the isothermal current theory, and the correlative curve between the surface trap density and its energy level is obtained. The maximum density of electron traps and hole traps in the surface layer of PTFE presents a similar value of ∼2.7 × 1017 eV-1 m-3, and the energy level of its electron and hole traps is of about 0.85-1.0 eV and 0.80-0.90 eV, respectively. Via the X-ray photoelectron spectroscopy (XPS) technique, the F, C, K and O elements are detected on the surface of PTFE samples, and F shows a remarkable atom proportion of ∼73.3%, quite different from the intrinsic distribution corresponding to its chemical formula. The electron traps are attributed to quantities of F atoms existing on the surface of PTFE due to its molecular chain with C atoms surrounded by F atoms spirally. It is considered that the distortions of chemical and electronic structure on solid surface are responsible for the flashover phenomena occurring at a low applied voltage.

Fine tuning the ionic liquid-vacuum outer atomic surface using ion mixtures.

PubMed

Villar-Garcia, Ignacio J; Fearn, Sarah; Ismail, Nur L; McIntosh, Alastair J S; Lovelock, Kevin R J

2015-03-28

Ionic liquid-vacuum outer atomic surfaces can be created that are remarkably different from the bulk composition. In this communication we demonstrate, using low-energy ion scattering (LEIS), that for ionic liquid mixtures the outer atomic surface shows significantly more atoms from anions with weaker cation-anion interactions (and vice versa).

Extraction of CO2 from air samples for isotopic analysis and limits to ultra high precision delta18O determination in CO2 gas.

PubMed

Werner, R A; Rothe, M; Brand, W A

2001-01-01

The determination of delta18O values in CO2 at a precision level of +/-0.02 per thousand (delta-notation) has always been a challenging, if not impossible, analytical task. Here, we demonstrate that beyond the usually assumed major cause of uncertainty - water contamination - there are other, hitherto underestimated sources of contamination and processes which can alter the oxygen isotope composition of CO2. Active surfaces in the preparation line with which CO2 comes into contact, as well as traces of air in the sample, can alter the apparent delta18O value both temporarily and permanently. We investigated the effects of different surface materials including electropolished stainless steel, Duran glass, gold and quartz, the latter both untreated and silanized. CO2 frozen with liquid nitrogen showed a transient alteration of the 18O/16O ratio on all surfaces tested. The time to recover from the alteration as well as the size of the alteration varied with surface type. Quartz that had been ultrasonically cleaned for several hours with high purity water (0.05 microS) exhibited the smallest effect on the measured oxygen isotopic composition of CO2 before and after freezing. However, quartz proved to be mechanically unstable with time when subjected to repeated large temperature changes during operation. After several days of operation the gas released from the freezing step contained progressively increasing trace amounts of O2 probably originating from inclusions within the quartz, which precludes the use of quartz for cryogenically trapping CO2. Stainless steel or gold proved to be suitable materials after proper pre-treatment. To ensure a high trapping efficiency of CO2 from a flow of gas, a cold trap design was chosen comprising a thin wall 1/4" outer tube and a 1/8" inner tube, made respectively from electropolished stainless steel and gold. Due to a considerable 18O specific isotope effect during the release of CO2 from the cold surface, the thawing time had to be as long as 20 min for high precision delta18O measurements. The presence of traces of air in almost all CO2 gases that we analyzed was another major source of error. Nitrogen and oxygen in the ion source of our mass spectrometer (MAT 252, Finnigan MAT, Bremen, Germany) give rise to the production of NO2 at the hot tungsten filament. NO2+ is isobaric with C16O18O+ (m/z 46) and interferes with the delta18O measurement. Trace amounts of air are present in CO2 extracted cryogenically from air at -196 degrees C. This air, trapped at the cold surface, cannot be pumped away quantitatively. The amount of air present depends on the surface structure and, hence, the alteration of the measured delta18O value varies with the surface conditions. For automated high precision measurement of the isotopic composition of CO2 of air samples stored in glass flasks an extraction interface ('BGC-AirTrap') was developed which allows 18 analyses (including standards) per day to be made. For our reference CO2-in-air, stored in high pressure cylinders, the long term (>9 months) single sample precision was 0.012 per thousand for delta13C and 0.019 per thousand for delta18O. Copyright 2001 John Wiley & Sons, Ltd.

Towards Quantum Simulations Using a Chip Ion Trap

NASA Astrophysics Data System (ADS)

Cao, Chenglin; Wright, Ken; Brennan, Daniel; Ji, Geoffrey; Monroe, Christopher

2013-05-01

We report our current experimental progress towards using chip ion traps for quantum simulation. Current progress is being made using a micro-fabricated symmetric trap from GTRI. This trap implements a novel two level design that combines the benefits of both surface traps and linear four-rod traps. The trap has 50 electrodes which allow for the fine control of the DC potential needed to create large anharmonic potentials, to join and split ion chains and to shuttle ions along the trapping axis similar to many surface traps. However this trap also has a much deeper trapping depth than conventional surface traps and improved optical access via an angled slot through the chip wide enough to accommodate higher power laser light which could cause surface charging or damage in a traditional chip trap. These advantages should allow trapping of long ion chains. We hope to use these features as the next step in increasing the size of current quantum simulations being done at Univ of Maryland, which are aimed at exploring quantum phenomena in spin systems in a regime inaccessible to classical simulation. This work is supported by grants from the U.S. Army Research Office with funding from the DARPA OLE program, IARPA, and the MURI program; and the NSF Physics Frontier Center at JQI. We acknowledge the GTRI team of J. Amini, K. Brown, A. Harter, F. Shaikh, R. Slusher, and C. Volin for the fabrication of the trap.

A Study of Particle Acceleration Mechanisms and the Dynamics of the Outer Trapping Region by Observations at Synchronous Orbit: a Summary of Scientific Results

NASA Technical Reports Server (NTRS)

Erickson, K. N.

1980-01-01

The research concerning the ATS-6 synchronous orbit satellite is reported. The completed research and results are discussed along with the research in progress. Abstracts of published papers are included.

IODIDE AEROSOL SORBENTS FOR MERCURY CAPTURE IN COMBUSTION EXHAUSTS

EPA Science Inventory

Several sorbent processes are being studied for their feasibility for mercury capture. Mercury is different from the other heavy metals as it is not as chemically reactive (due to a filled outer electronic shell), thus making it difficult for sorbents to chemically trap it (a). ...

Apparatus for premixing in a gas turbine engine

DOEpatents

McCormick, Keith Alan; Smith, Duane A.

2002-01-01

An apparatus for mixing fuel with oxidizing agent is disclosed comprising an outer body and an inner body. The outer body has an interior surface extending between an inlet end toward an outlet end. The interior surface includes a first plurality of openings. The inner body has an exterior surface extending between the first end and the second end of the inner body. The exterior surface of the inner body includes a second plurality of openings. At least a portion of the exterior surface of the inner body is positioned within the outer body to define a mixing channel between the exterior surface of the inner body and the interior surface of the outer body. In one form the first and second plurality of openings substantially longitudinally span at least one of the outer body and the inner body. In another form the first and second plurality of openings are substantially radially oriented. In yet another form the first and second plurality of openings are offset from one another.

A new concept of a hybrid trapped field magnet lens

NASA Astrophysics Data System (ADS)

Takahashi, Keita; Fujishiro, Hiroyuki; Ainslie, Mark D.

2018-04-01

In this paper, a new concept of a hybrid trapped field magnet lens (HTFML) is proposed. The HTMFL exploits the ‘vortex pinning effect’ of an outer superconducting bulk cylinder, which is magnetized as a trapped field magnet (TFM) using field-cooled magnetization (FCM), and the ‘diamagnetic shielding effect’ of an inner bulk magnetic lens to generate a concentrated magnetic field higher than the trapped field from the TFM in the bore of the magnetic lens. This requires that, during the zero-field-cooled magnetization process, the outer cylinder is in the normal state (T> superconducting transition temperature, T c) and the inner lens is in the superconducting state (T < T c) when the external magnetizing field is applied, followed by cooling to an appropriate operating temperature, then removing the external field. This is explored for two potential cases: (1) exploiting the difference in T c of two different bulk materials (‘case-1’), e.g. MgB2 (T c = 39 K) and GdBaCuO (T c = 92 K) or (2) using the same material for the whole HTFML, e.g., GdBaCuO, but utilizing individually controlled cryostats, the same cryostat with different cooling loops or coolants, or heaters that keep the outer bulk cylinder at a temperature above T c to achieve the same desired effect. The HTFML is verified using numerical simulations for ‘case-1’ using an MgB2 cylinder and GdBaCuO lens pair and for ‘case-2’ using a GdBaCuO cylinder and GdBaCuO lens pair. As a result, the HTFML could reliably generate a concentrated magnetic field B c = 4.73 T with the external magnetizing field B app = 3 T in the ‘case-1’, and a higher B c = 13.49 T with higher B app = 10 T in the ‘case-2’, respectively. This could, for example, be used to enhance the magnetic field in the bore of a bulk superconducting NMR/MRI system to improve its resolution.

Systems to facilitate reducing flashback/flame holding in combustion systems

DOEpatents

Lacy, Benjamin Paul [Greer, SC; Kraemer, Gilbert Otto [Greer, SC; Varatharajan, Balachandar [Clifton Park, NY; Yilmaz, Ertan [Albany, NY; Zuo, Baifang [Simpsonville, SC

2012-02-21

A method for assembling a premixing injector is provided. The method includes providing a centerbody including a center axis and a radially outer surface, and providing an inlet flow conditioner. The inlet flow conditioner includes a radially outer wall, a radially inner wall, and an end wall coupled substantially perpendicularly between the outer wall and the inner wall. Each of the outer wall and the end wall include a plurality of openings defined therein. The outer wall, the inner wall, and the end wall define a first passage therebetween. The method also includes coupling the inlet flow conditioner to the centerbody such that the inlet flow conditioner substantially circumscribes the centerbody, such that the inner wall is substantially parallel to the centerbody outer surface, and such that a second passage is defined between the centerbody outer surface and the inner wall.

Micro-cone targets for producing high energy and low divergence particle beams

DOEpatents

Le Galloudec, Nathalie

2013-09-10

The present invention relates to micro-cone targets for producing high energy and low divergence particle beams. In one embodiment, the micro-cone target includes a substantially cone-shaped body including an outer surface, an inner surface, a generally flat and round, open-ended base, and a tip defining an apex. The cone-shaped body tapers along its length from the generally flat and round, open-ended base to the tip defining the apex. In addition, the outer surface and the inner surface connect the base to the tip, and the tip curves inwardly to define an outer surface that is concave, which is bounded by a rim formed at a juncture where the outer surface meets the tip.

Frame-mounted wire management device

DOEpatents

Grushkowitz, Tyler; Fischer, Kevin; Danning, Matthew

2016-09-20

A wire management device is disclosed. The device comprises a clip comprising an upper planar member and a lower planar member, each planar member having an inner and outer surface, wherein the inner surface of the upper planar member includes a post extending toward the inner surface of the lower planar member, a stem extending from the outer surface of the lower planar member, the stem including two outwardly-extending flanges, each of the first and second outwardly-extending flanges including an edge portion extending toward the outer surface of the lower planar member, and a transverse passage extending along the outer surface of the lower planar member, the transverse passage extending across the stem, wherein the stem has a recessed portion along the transverse passage.

Physical understanding of trends in current collapse with atomic layer deposited dielectrics in AlGaN/GaN MOS heterojunction FETs

NASA Astrophysics Data System (ADS)

Ramanan, Narayanan; Lee, Bongmook; Misra, Veena

2016-03-01

Many passivation dielectrics are pursued for suppressing current collapse due to trapping/detrapping of access-region surface traps in AlGaN/GaN based metal oxide semiconductor heterojuction field effect transistors (MOS-HFETs). The suppression of current collapse can potentially be achieved either by reducing the interaction of surface traps with the gate via surface leakage current reduction, or by eliminating surface traps that can interact with the gate. But, the latter is undesirable since a high density of surface donor traps is required to sustain a high 2D electron gas density at the AlGaN/GaN heterointerface and provide a low ON-resistance. This presents a practical trade-off wherein a passivation dielectric with the optimal surface trap characteristics and minimal surface leakage is to be chosen. In this work, we compare MOS-HFETs fabricated with popular ALD gate/passivation dielectrics like SiO2, Al2O3, HfO2 and HfAlO along with an additional thick plasma-enhanced chemical vapor deposition SiO2 passivation. It is found that after annealing in N2 at 700 °C, the stack containing ALD HfAlO provides a combination of low surface leakage and a high density of shallow donor traps. Physics-based TCAD simulations confirm that this combination of properties helps quick de-trapping and minimal current collapse along with a low ON resistance.

Nearly extremal apparent horizons in simulations of merging black holes

NASA Astrophysics Data System (ADS)

Lovelace, Geoffrey; Scheel, Mark A.; Owen, Robert; Giesler, Matthew; Katebi, Reza; Szilágyi, Béla; Chu, Tony; Demos, Nicholas; Hemberger, Daniel A.; Kidder, Lawrence E.; Pfeiffer, Harald P.; Afshari, Nousha

2015-03-01

The spin angular momentum S of an isolated Kerr black hole is bounded by the surface area A of its apparent horizon: 8π S≤slant A, with equality for extremal black holes. In this paper, we explore the extremality of individual and common apparent horizons for merging, rapidly spinning binary black holes. We consider simulations of merging black holes with equal masses M and initial spin angular momenta aligned with the orbital angular momentum, including new simulations with spin magnitudes up to S/{{M}2}=0.994. We measure the area and (using approximate Killing vectors) the spin on the individual and common apparent horizons, finding that the inequality 8π S\\lt A is satisfied in all cases but is very close to equality on the common apparent horizon at the instant it first appears. We also evaluate the Booth-Fairhurst extremality, whose value for a given apparent horizon depends on the scaling of the horizon’s null normal vectors. In particular, we introduce a gauge-invariant lower bound on the extremality by computing the smallest value that Booth and Fairhurst’s extremality parameter can take for any scaling. Using this lower bound, we conclude that the common horizons are at least moderately close to extremal just after they appear. Finally, following Lovelace et al (2008 Phys. Rev. D 78 084017), we construct quasiequilibrium binary-black hole initial data with ‘overspun’ marginally trapped surfaces with 8π S\\gt A. We show that the overspun surfaces are indeed superextremal: our lower bound on their Booth-Fairhurst extremality exceeds unity. However, we confirm that these superextremal surfaces are always surrounded by marginally outer trapped surfaces (i.e., by apparent horizons) with 8π S\\lt A. The extremality lower bound on the enclosing apparent horizon is always less than unity but can exceed the value for an extremal Kerr black hole.

Modeling Subsidence-Like Events on Cometary Nuclei

NASA Astrophysics Data System (ADS)

Rosenberg, Eric; Prialnik, Dina

2017-10-01

There is ample evidence, particularly from the Rosetta mission, that cometary nuclei have very low tensile strength. Consequently, morphological changes are expected to occur, caused by buildup of pressure due to gas release in the interior of the nucleus. Such changes have been observed on the surface of comet 67P/Churyumov-Gerasimenko, as reported for example by Groussin et al.(2015). A mechanism for explaining comet surface depressions has been recently proposed by Prialnik & Sierks (2017). Here we report on a numerical study, elaborating on this mechanism. Essentially, the model considers a cometary nucleus composed of a low-density mixture of ice and dust, assuming that the ice is amorphous and traps volatile gasses, such as CO and CO2. The model assumes that the tensile strength of the subsurface material is low and that the surface is covered by a thin crust of low permeability. As the comet evolves, the amorphous ice crystallizes, and the crystallization front recedes from the surface, releasing the trapped gasses, which accumulate beneath the surface, building up pressure. The gas pressure weakens the material strength, but sustains the gas-filled layer against hydrostatic pressure. Eventually, the gas will break its way through the outer crust in an outburst. The rapid pressure drop may cause the collapse of the gas depleted layer, as seen on the nucleus of 67P/Churyumov-Gerasimenko. This mechanism is similar to subsidence events in gas fields on earth.We have performed quasi-3D numerical simulations in an attempt to determine the extent of the area that would be affected by such a mechanism. The frequency of such subsidence events and the depth of the collapse are investigated as functions of solar angle and spin axis inclination. The necessary conditions for outburst-induced collapse are determined and confronted with observations.References:Groussin, O., Sierks, H., et al. 2015, A&A, 583, A35Prialnik, D. & Sierks, H., 2017, MNRAS, in press

Loading an Equidistant Ion Chain in a Ring Shaped Surface Trap and Anomalous Heating Studies with a High Optical Access Trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tabakov, Boyan

2015-07-01

Microfabricated segmented surface ion traps are one viable avenue to scalable quantum information processing. At Sandia National Laboratories we design, fabricate, and characterize such traps. Our unique fabrication capabilities allow us to design traps that facilitate tasks beyond quantum information processing. The design and performance of a trap with a target capability of storing hundreds of equally spaced ions on a ring is described. Such a device could aid experimental studies of phenomena as diverse as Hawking radiation, quantum phase transitions, and the Aharonov - Bohm effect. The fabricated device is demonstrated to hold a ~ 400 ion circular crystal,more » with 9 μm average spacing between ions. The task is accomplished by first characterizing undesired electric fields in the trapping volume and then designing and applying an electric field that substantially reduces the undesired fields. In addition, experimental efforts are described to reduce the motional heating rates in a surface trap by low energy in situ argon plasma treatment that reduces the amount of surface contaminants. The experiment explores the premise that carbonaceous compounds present on the surface contribute to the anomalous heating of secular motion modes in surface traps. This is a research area of fundamental interest to the ion trapping community, as heating adversely affects coherence and thus gate fidelity. The device used provides high optical laser access, substantially reducing scatter from the surface, and thus charging that may lead to excess micromotion. Heating rates for different axial mode frequencies are compared before and after plasma treatment. The presence of a carbon source near the plasma prevents making a conclusion on the observed absence of change in heating rates.« less

Histophilus somni causes extracellular trap formation by bovine neutrophils and macrophages.

PubMed

Hellenbrand, Katrina M; Forsythe, Katelyn M; Rivera-Rivas, Jose J; Czuprynski, Charles J; Aulik, Nicole A

2013-01-01

Histophilus somni (formerly Haemophilus somnus) is a Gram-negative pleomorphic coccobacillus that causes respiratory, reproductive, cardiac and neuronal diseases in cattle. H. somni is a member of the bovine respiratory disease complex that causes severe bronchopneumonia in cattle. Previously, it has been reported that bovine neutrophils and macrophages have limited ability to phagocytose and kill H. somni. Recently, it was discovered that bovine neutrophils and macrophages produce extracellular traps in response to Mannheimia haemolytica, another member of the bovine respiratory disease complex. In this study, we demonstrate that H. somni also causes extracellular trap production by bovine neutrophils in a dose- and time-dependent manner, which did not coincide with the release of lactate dehydrogenase, a marker for necrosis. Neutrophil extracellular traps were produced in response to outer membrane vesicles, but not lipooligosacchride alone. Using scanning electron microscopy and confocal microscopy, we observed H. somni cells trapped within a web-like structure. Further analyses demonstrated that bovine neutrophils trapped and killed H. somni in a DNA-dependent manner. Treatment of DNA extracellular traps with DNase I freed H. somni cells and diminished bacterial death. Treatment of bovine monocyte-derived macrophages with H. somni cells also caused macrophage extracellular trap formation. These findings suggest that extracellular traps may play a role in the host response to H. somni infection in cattle. Copyright © 2012 Elsevier Ltd. All rights reserved.

78 FR 35217 - Atlantic Coastal Fisheries Cooperative Management Act Provisions; American Lobster Fishery

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-12

.... 080219213-3470-01] RIN 0648-AT31 Atlantic Coastal Fisheries Cooperative Management Act Provisions; American... lobster trap fishery in Lobster Conservation Management Area 2 (Federal nearshore waters in Southern New England; Area 2), and in the Outer Cape Cod Lobster Conservation Management Area (Federal nearshore waters...

A new mute species of the genus Nemobius Serville (Orthoptera, Gryllidae, Nemobiinae) discovered in colluvial, stony debris in the Iberian Peninsula: A biological, phenological and biometric study.

PubMed

Barranco, Pablo; Gilgado, José D; Ortuno, Vicente M

2013-01-01

Sampling of a Mesovoid Shallow Substratum (MSS) of a scree in the Guadarrama mountains (Madrid, Spain) revealed a population of crickets of the genus Nemobius Serville. A detailed morphological study revealed that the cricket was a new species, Nemobius interstitialis sp. nov., which is principally characterized by the absence of a tympanum in the outer margin of the foreleg tibiae and a peculiar design of venation of the forewing of the male. Sampling of this environment over 1 year using surface and MSS pitfall traps, set at a depth of one meter, allowed study of population dynamics. A population maximum is attained in August. Abiotic (temperature and humidity) and biotic (accompanying fauna) data are given to contextualize the habitat of this new species.

Non-binding conductor load bearing roller for a gas-insulated transmission line having a corrugated outer conductor

DOEpatents

Fischer, William H.

1984-01-01

A gas-insulated transmission line includes a corrugated outer conductor, an inner conductor disposed within and insulated from the outer conductor by means of support insulators and an insulating gas, and a non-binding transport device for supporting and permitting movement of the inner conductor/insulating support assembly axially along the corrugated outer conductor without radial displacement and for moving without binding along corrugations of any slope less than vertical. The transport device includes two movable contacts, such as skids or rollers, supported on a common pivot lever, the pivot lever being rotatably disposed about a pivot lever axis, which pivot lever axis is in turn disposed on the periphery of a support insulator or particle trap if one is used. The movable contacts are separated axially a distance equal to the axial distance between the peaks and valleys of the corrugations of the outer conductor and separated radially a distance equal to the radial distance between the peaks and valleys of the corrugations of the outer conductor. The transport device has the pivot lever axis disposed parallel to the motion of travel of the inner conductor/insulating support assembly.

Resurrecting Inactive Antimicrobial Peptides from the Lipopolysaccharide Trap

PubMed Central

Mohanram, Harini

2014-01-01

Host defense antimicrobial peptides (AMPs) are a promising source of antibiotics for the treatment of multiple-drug-resistant pathogens. Lipopolysaccharide (LPS), the major component of the outer leaflet of the outer membrane of Gram-negative bacteria, functions as a permeability barrier against a variety of molecules, including AMPs. Further, LPS or endotoxin is the causative agent of sepsis killing 100,000 people per year in the United States alone. LPS can restrict the activity of AMPs inducing aggregations at the outer membrane, as observed for frog AMPs, temporins, and also in model AMPs. Aggregated AMPs, “trapped” by the outer membrane, are unable to traverse the cell wall, causing their inactivation. In this work, we show that these inactive AMPs can overcome LPS-induced aggregations while conjugated with a short LPS binding β-boomerang peptide motif and become highly bactericidal. The generated hybrid peptides exhibit activity against Gram-negative and Gram-positive bacteria in high-salt conditions and detoxify endotoxin. Structural and biophysical studies establish the mechanism of action of these peptides in LPS outer membrane. Most importantly, this study provides a new concept for the development of a potent broad-spectrum antibiotic with efficient outer membrane disruption as the mode of action. PMID:24419338

On Magnetic Flux Trapping by Surface Superconductivity

NASA Astrophysics Data System (ADS)

Podolyak, E. R.

2018-03-01

The magnetic flux trapping by surface superconductivity is considered. The stability of the state localized at the cylindrical sample surface upon a change in the external magnetic field is tested. It is shown that as the magnetic field decreases, the sample acquires a positive magnetic moment due to magnetic flux trapping; i.e., the magnetization curve of surface superconductivity is "paramagnetic" by nature.

A Model for AR Scorpii: Emission from Relativistic Electrons Trapped by Closed Magnetic Field Lines of Magnetic White Dwarfs

NASA Astrophysics Data System (ADS)

Takata, J.; Yang, H.; Cheng, K. S.

2017-12-01

AR Scorpii is an intermediate polar binary system composed of a magnetic white dwarf (WD) and an M-type star and shows nonthermal, pulsed, and highly linearly polarized emission. The radio/optical emission modulates with the WD’s spin and shows the double-peak structure in the light curves. In this paper, we discuss a possible scenario for the radiation mechanism of AR Scorpii. The magnetic interaction on the surface of the companion star produces an outflow from the companion star, the heating of the companion star surface, and the acceleration of electrons to a relativistic energy. The accelerated electrons, whose typical Lorentz factor is ∼50–100, from the companion star move along the magnetic field lines toward the WD surface. The electrons injected with the pitch angle of \\sin {θ }p,0> 0.05 are subject to the magnetic mirror effect and are trapped in the closed magnetic field line region. We find that the emission from the first magnetic mirror points mainly contributes to the observed pulsed emission and the formation of the double-peak structure in the light curve. For the inclined rotator, the pulse peak in the calculated light curve shifts the position in the spin phase, and a Fourier analysis exhibits a beat frequency feature, which are consistent with the optical/UV observations. The pulse profile also evolves with the orbital phase owing to the effect of the viewing geometry. The model also interprets the global features of the observed spectral energy distribution in radio to X-ray energy bands. We also discuss the curvature radiation and the inverse-Compton scattering process in the outer gap accelerator of the WD in AR Scorpii and the possibility of the detection by future high-energy missions.

Ball-grid array architecture for microfabricated ion traps

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guise, Nicholas D., E-mail: nicholas.guise@gtri.gatech.edu; Fallek, Spencer D.; Stevens, Kelly E.

2015-05-07

State-of-the-art microfabricated ion traps for quantum information research are approaching nearly one hundred control electrodes. We report here on the development and testing of a new architecture for microfabricated ion traps, built around ball-grid array (BGA) connections, that is suitable for increasingly complex trap designs. In the BGA trap, through-substrate vias bring electrical signals from the back side of the trap die to the surface trap structure on the top side. Gold-ball bump bonds connect the back side of the trap die to an interposer for signal routing from the carrier. Trench capacitors fabricated into the trap die replace area-intensivemore » surface or edge capacitors. Wirebonds in the BGA architecture are moved to the interposer. These last two features allow the trap die to be reduced to only the area required to produce trapping fields. The smaller trap dimensions allow tight focusing of an addressing laser beam for fast single-qubit rotations. Performance of the BGA trap as characterized with {sup 40}Ca{sup +} ions is comparable to previous surface-electrode traps in terms of ion heating rate, mode frequency stability, and storage lifetime. We demonstrate two-qubit entanglement operations with {sup 171}Yb{sup +} ions in a second BGA trap.« less

Interfacial dynamic surface traps of lead sulfide (PbS) nanocrystals: test-platform for interfacial charge carrier traps at the organic/inorganic functional interface

NASA Astrophysics Data System (ADS)

Kim, Youngjun; Ko, Hyungduk; Park, Byoungnam

2018-04-01

Nanocrystal (NC) size and ligand dependent dynamic trap formation of lead sulfide (PbS) NCs in contact with an organic semiconductor were investigated using a pentacene/PbS field effect transistor (FET). We used a bilayer pentacene/PbS FET to extract information of the surface traps of PbS NCs at the pentacene/PbS interface through the field effect-induced charge carrier density measurement in the threshold and subthreshold regions. PbS size and ligand dependent trap properties were elucidated by the time domain and threshold voltage measurements in which threshold voltage shift occurs by carrier charging and discharging in the trap states of PbS NCs. The observed threshold voltage shift is interpreted in context of electron trapping through dynamic trap formation associated with PbS NCs. To the best of our knowledge, this is the first demonstration of the presence of interfacial dynamic trap density of PbS NC in contact with an organic semiconductor (pentacene). We found that the dynamic trap density of the PbS NC is size dependent and the carrier residence time in the specific trap sites is more sensitive to NC size variation than to NC ligand exchange. The probing method presented in the study offers a means to investigate the interfacial surface traps at the organic-inorganic hetero-junction, otherwise understanding of the buried surface traps at the functional interface would be elusive.

The surface emissions trap: a new approach in indoor air purification.

PubMed

Markowicz, Pawel; Larsson, Lennart

2012-11-01

A new device for stopping or reducing potentially irritating or harmful emissions from surfaces indoors is described. The device is a surface emissions trap prototype and consists of an adsorbent sheet with a semipermeable barrier surrounded by two thin nonwoven layers. The trap may be applied directly at the source of the emissions e.g. at moisture-affected floors and walls, surfaces contaminated by chemical spills etc. This results in an immediate stop or reduction of the emitting pollutants. The trap has a very low water vapor resistance thus allowing drying of wet surfaces. In laboratory experiments typically 98% reduction of air concentrations of volatile organic compounds and a virtually total reduction of mold particle-associated mycotoxins was observed. The surface emissions trap may represent a convenient and efficient way of restoring indoor environments polluted by microbial and other moisture-associated emissions. Copyright © 2012 Elsevier B.V. All rights reserved.

Reduction of Trapped-Ion Anomalous Heating by in situ Surface Plasma Cleaning

DTIC Science & Technology

2015-04-29

the trap chip temperature. To load ions, we initially cool 88Sr atoms into a remotely-located magneto - optical trap (MOT), then use a resonant push beam... trap heating rates [10]. Furthermore, some previous experiments have shown an improvement in the heating rates of surface-electrode ion traps after...rate when the trap chip is held at 4 K is not significantly improved by the plasma cleaning. While the observed frequency scaling is not the same in

Floating nut retention system

NASA Technical Reports Server (NTRS)

Charles, J. F.; Theakston, H. A. (Inventor)

1980-01-01

A floating nut retention system includes a nut with a central aperture. An inner retainer plate has an opening which is fixedly aligned with the nut aperture. An outer retainer member is formed of a base plate having an opening and a surface adjacent to a surface of the inner retainer plate. The outer retainer member includes a securing mechanism for retaining the inner retainer plate adjacent to the outer retainer member. The securing mechanism enables the inner retainer plate to float with respect to the outer retainer number, while simultaneously forming a bearing surface for inner retainer plate.

Captures of Boll Weevils (Coleoptera: Curculionidae) in Relation to Trap Distance From Cotton Fields.

PubMed

Spurgeon, Dale W

2016-12-01

The boll weevil (Anthonomus grandis grandis Boheman) has been eradicated from much of the United States, but remains an important pest of cotton (Gossypium spp.) in other parts of the Americas. Where the weevil occurs, the pheromone trap is a key tool for population monitoring or detection. Traditional monitoring programs have placed traps in or near the outermost cotton rows where damage by farm equipment can cause loss of trapping data. Recently, some programs have adopted a trap placement adjacent to but outside monitored fields. The effects of these changes have not been previously reported. Captures of early-season boll weevils by traps near (≤1 m) or far (7-10 m) from the outermost cotton row were evaluated. In 2005, during renewed efforts to eradicate the boll weevil from the Lower Rio Grande Valley of Texas, far traps consistently captured more weevils than traps near cotton. Traps at both placements indicated similar patterns of early-season weevil captures, which were consistent with those previously reported. In 2006, no distinction between trap placements was detected. Early-season patterns of captures in 2006 were again similar for both trap placements, but captures were much lower and less regular compared with those observed in 2005. These results suggest magnitude and likelihood of weevil capture in traps placed away from cotton are at least as high as for traps adjacent to cotton. Therefore, relocation of traps away from the outer rows of cotton should not negatively impact ability to monitor or detect the boll weevil. Published by Oxford University Press on behalf of Entomological Society of America 2016. This work is written by a US Government employee and is in the public domain in the US.

Sediment traps for measuring onslope surface sediment movement

Treesearch

Wade G. Wells; Peter M. Wohlgemuth

1987-01-01

Two types of small (30-cm aperture) sheet metal sediment traps were developed to monitor onslope surface sediment transport. Traditionally, sediment traps and erosion pins have been used to measure the onslope movement of surficial soil material. While pins may be appropriate for documenting landscape denudation, traps are more suitable for monitoring downslope...

Scanning dimensional measurement using laser-trapped microsphere with optical standing-wave scale

NASA Astrophysics Data System (ADS)

Michihata, Masaki; Ueda, Shin-ichi; Takahashi, Satoru; Takamasu, Kiyoshi; Takaya, Yasuhiro

2017-06-01

We propose a laser trapping-based scanning dimensional measurement method for free-form surfaces. We previously developed a laser trapping-based microprobe for three-dimensional coordinate metrology. This probe performs two types of measurements: a tactile coordinate and a scanning measurement in the same coordinate system. The proposed scanning measurement exploits optical interference. A standing-wave field is generated between the laser-trapped microsphere and the measured surface because of the interference from the retroreflected light. The standing-wave field produces an effective length scale, and the trapped microsphere acts as a sensor to read this scale. A horizontal scan of the trapped microsphere produces a phase shift of the standing wave according to the surface topography. This shift can be measured from the change in the microsphere position. The dynamics of the trapped microsphere within the standing-wave field was estimated using a harmonic model, from which the measured surface can be reconstructed. A spherical lens was measured experimentally, yielding a radius of curvature of 2.59 mm, in agreement with the nominal specification (2.60 mm). The difference between the measured points and a spherical fitted curve was 96 nm, which demonstrates the scanning function of the laser trapping-based microprobe for free-form surfaces.

System and method for underwater radiography

DOEpatents

Hunter, James; Keck, Danny Lee; Sims, Jr., James Rae; Watson, Scott Avery

2015-01-20

A system for subsea imaging comprises a first plate having an inner surface, an outer surface, and a cavity formed in the inner surface. In addition, the system comprises a phosphor imaging plate disposed in the cavity. Further, the system comprises a second plate having an inner surface facing the inner surface of the first plate and an outer surface facing away from the outer surface of the first plate. Still further, the system comprises a seal member disposed between the inner surface of the first plate and the inner surface of the second plate. The seal member extends around the perimeter of the cavity and is configured to seal the phosphor imaging plate and the cavity from intrusion water.

Hot gas path component cooling system

DOEpatents

Lacy, Benjamin Paul; Bunker, Ronald Scott; Itzel, Gary Michael

2014-02-18

A cooling system for a hot gas path component is disclosed. The cooling system may include a component layer and a cover layer. The component layer may include a first inner surface and a second outer surface. The second outer surface may define a plurality of channels. The component layer may further define a plurality of passages extending generally between the first inner surface and the second outer surface. Each of the plurality of channels may be fluidly connected to at least one of the plurality of passages. The cover layer may be situated adjacent the second outer surface of the component layer. The plurality of passages may be configured to flow a cooling medium to the plurality of channels and provide impingement cooling to the cover layer. The plurality of channels may be configured to flow cooling medium therethrough, cooling the cover layer.

Diffusion mediated localization on membrane surfaces

NASA Technical Reports Server (NTRS)

Weaver, D. L.

1982-01-01

Using the model of a cell membrane of a spherical surface in which membrane components may diffuse, the rate of localization due to trapping under diffusion control has been estimated by computing an analytical expression for the mean trapping time including the possibilities of a trapping probability less than one and/or the establishment of an equilibrium at the trap boundary.

Methods and apparatus for radially compliant component mounting

DOEpatents

Bulman, David Edward [Cincinnati, OH; Darkins, Jr., Toby George; Stumpf, James Anthony [Columbus, IN; Schroder, Mark S [Greenville, SC; Lipinski, John Joseph [Simpsonville, SC

2012-03-27

Methods and apparatus for a mounting assembly for a liner of a gas turbine engine combustor are provided. The combustor includes a combustor liner and a radially outer annular flow sleeve. The mounting assembly includes an inner ring surrounding a radially outer surface of the liner and including a plurality of axially extending fingers. The mounting assembly also includes a radially outer ring coupled to the inner ring through a plurality of spacers that extend radially from a radially outer surface of the inner ring to the outer ring.

Electrochemical cell design

DOEpatents

Arntzen, John D.

1978-01-01

An electrochemical cell includes two outer electrodes and a central electrode of opposite polarity, all nested within a housing having two symmetrical halves which together form an offset configuration. The outer electrodes are nested within raised portions within the side walls of each housing half while the central electrode sealingly engages the perimetric margins of the side-wall internal surfaces. Suitable interelectrode separators and electrical insulating material electrically isolate the central electrode from the housing and the outer electrodes. The outer electrodes are electrically connected to the internal surfaces of the cell housing to provide current collection. The nested structure minimizes void volume that would otherwise be filled with gas or heavy electrolyte and also provides perimetric edge surfaces for sealing and supporting at the outer margins of frangible interelectrode separator layers.

Apparatus and filtering systems relating to combustors in combustion turbine engines

DOEpatents

Johnson, Thomas Edward [Greer, SC; Zuo, Baifang [Simpsonville, SC; Stevenson, Christian Xavier [Inman, SC

2012-07-24

A combustor for a combustion turbine engine, the combustor that includes: a chamber defined by an outer wall and forming a channel between windows defined through the outer wall toward a forward end of the chamber and at least one fuel injector positioned toward an aft end of the chamber; a screen; and a standoff comprising a raised area on an outer surface of the outer wall near the periphery of the windows; wherein the screen extends over the windows and is supported by the standoff in a raised position in relation to the outer surface of the outer wall and the windows.

Direct probing of electron and hole trapping into nano-floating-gate in organic field-effect transistor nonvolatile memories

NASA Astrophysics Data System (ADS)

Cui, Ze-Qun; Wang, Shun; Chen, Jian-Mei; Gao, Xu; Dong, Bin; Chi, Li-Feng; Wang, Sui-Dong

2015-03-01

Electron and hole trapping into the nano-floating-gate of a pentacene-based organic field-effect transistor nonvolatile memory is directly probed by Kelvin probe force microscopy. The probing is straightforward and non-destructive. The measured surface potential change can quantitatively profile the charge trapping, and the surface characterization results are in good accord with the corresponding device behavior. Both electrons and holes can be trapped into the nano-floating-gate, with a preference of electron trapping than hole trapping. The trapped charge quantity has an approximately linear relation with the programming/erasing gate bias, indicating that the charge trapping in the device is a field-controlled process.

Trapped particle stability for the kinetic stabilizer

NASA Astrophysics Data System (ADS)

Berk, H. L.; Pratt, J.

2011-08-01

A kinetically stabilized axially symmetric tandem mirror (KSTM) uses the momentum flux of low-energy, unconfined particles that sample only the outer end-regions of the mirror plugs, where large favourable field-line curvature exists. The window of operation is determined for achieving magnetohydrodynamic (MHD) stability with tolerable energy drain from the kinetic stabilizer. Then MHD stable systems are analysed for stability of the trapped particle mode. This mode is characterized by the detachment of the central-cell plasma from the kinetic-stabilizer region without inducing field-line bending. Stability of the trapped particle mode is sensitive to the electron connection between the stabilizer and the end plug. It is found that the stability condition for the trapped particle mode is more constraining than the stability condition for the MHD mode, and it is challenging to satisfy the required power constraint. Furthermore, a severe power drain may arise from the necessary connection of low-energy electrons in the kinetic stabilizer to the central region.

Surface electroluminescence phenomena correlated with trapping parameters of insulating polymers

NASA Astrophysics Data System (ADS)

Zhang, Guan-Jun; Yang, Kai; Dong, Ming; Zhao, Wen-Bin; Yan, Zhang

2007-12-01

Electroluminescence (EL) phenomena are closely linked to the space charge and degradation in insulating polymers, and dominated by the luminescence and trap centers. EL emission has been promising in defining the onset of electrical aging and in the investigation of dissipation mechanisms. Generally, polymeric degradation reveals the increment of the density of luminescence and trap centers, so a fundamental study is proposed to correlate the EL emission of insulating polymers and their trapping parameters. A sensitive photon counting system is constructed to detect the weak EL. The time- and phase-resolved EL characteristics from different polymers (LDPE, PP and PTFE) are investigated with a planar electrode configuration under stepped ac voltage in vacuum. In succession, each sample is charged with exposing to multi-needle corona discharge, and then its surface potential decay is continuously recorded at a constant temperature. Based on the isothermal relaxation current theory, the energy level and density of both electron and hole trap distribution in the surface layer of each polymer is obtained. It is preliminarily concluded that EL phenomena are strongly affected by the trap properties, and for different polymers, its EL intensity is in direct contrast to its surface trap density, and this can be qualitatively explained by the trapping and detrapping sequence of charge carriers in trap centers with different energy level.

Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors.

PubMed

He, Tao; Wu, Yanfei; D'Avino, Gabriele; Schmidt, Elliot; Stolte, Matthias; Cornil, Jérôme; Beljonne, David; Ruden, P Paul; Würthner, Frank; Frisbie, C Daniel

2018-05-30

Understanding relationships between microstructure and electrical transport is an important goal for the materials science of organic semiconductors. Combining high-resolution surface potential mapping by scanning Kelvin probe microscopy (SKPM) with systematic field effect transport measurements, we show that step edges can trap electrons on the surfaces of single crystal organic semiconductors. n-type organic semiconductor crystals exhibiting positive step edge surface potentials display threshold voltages that increase and carrier mobilities that decrease with increasing step density, characteristic of trapping, whereas crystals that do not have positive step edge surface potentials do not have strongly step density dependent transport. A device model and microelectrostatics calculations suggest that trapping can be intrinsic to step edges for crystals of molecules with polar substituents. The results provide a unique example of a specific microstructure-charge trapping relationship and highlight the utility of surface potential imaging in combination with transport measurements as a productive strategy for uncovering microscopic structure-property relationships in organic semiconductors.

Determination of the thermal stress wave propagation in orthotropic hollow cylinder based on classical theory of thermoelasticity

NASA Astrophysics Data System (ADS)

Shahani, Amir Reza; Sharifi Torki, Hamid

2018-01-01

The thermoelasticity problem in a thick-walled orthotropic hollow cylinder is solved analytically using finite Hankel transform and Laplace transform. Time-dependent thermal and mechanical boundary conditions are applied on the inner and the outer surfaces of the cylinder. For solving the energy equation, the temperature itself is considered as boundary condition to be applied on both the inner and the outer surfaces of the orthotropic cylinder. Two different cases are assumed for solving the equation of motion: traction-traction problem (tractions are prescribed on both the inner and the outer surfaces) and traction-displacement (traction is prescribed on the inner surface and displacement is prescribed on the outer surface of the hollow orthotropic cylinder). Due to considering uncoupled theory, after obtaining temperature distribution, the dynamical structural problem is solved and closed-form relations are derived for radial displacement, radial and hoop stress. As a case study, exponentially decaying temperature with respect to time is prescribed on the inner surface of the cylinder and the temperature of the outer surface is considered to be zero. Owing to solving dynamical problem, the stress wave propagation and its reflections were observed after plotting the results in both cases.

The thermally stimulated discharge of ion-irradiated oxide films

NASA Astrophysics Data System (ADS)

Wang, Qiuru; Zeng, Huizhong; Zhang, Wanli

2018-01-01

The ion irradiation technique is utilized to modify the surface structure of amorphous insulating oxide films. While introducing defects, a number of surface charges are injected into the films and captured in the traps during ion irradiation. The variation of surface morphology and the enhancement of emission spectrum corresponding to vacancy defects are respectively verified by atomic force microscopy and photoluminescence measurements. The surface charges trapped in the shallow traps are easy to release caused by thermal excitation, and discharge is observed during heating. Based on the thermally stimulated discharge measurements, the trap parameters of oxide films, such as activation energy and relaxation time, are calculated from experimental data.

Thermal Protection System with Staggered Joints

NASA Technical Reports Server (NTRS)

Simon, Xavier D. (Inventor); Robinson, Michael J. (Inventor); Andrews, Thomas L. (Inventor)

2014-01-01

The thermal protection system disclosed herein is suitable for use with a spacecraft such as a reentry module or vehicle, where the spacecraft has a convex surface to be protected. An embodiment of the thermal protection system includes a plurality of heat resistant panels, each having an outer surface configured for exposure to atmosphere, an inner surface opposite the outer surface and configured for attachment to the convex surface of the spacecraft, and a joint edge defined between the outer surface and the inner surface. The joint edges of adjacent ones of the heat resistant panels are configured to mate with each other to form staggered joints that run between the peak of the convex surface and the base section of the convex surface.

Self-assisted optothermal trapping of gold nanorods under two-photon excitation

PubMed Central

Chen, Hongtao; Gratton, Enrico; Digman, Michelle A

2017-01-01

We report a self-assisted optothermal trapping and patterning of gold nanorods (GNRs) on glass surfaces with a femtosecond laser. We show that GNRs are not only the trapping targets, but also can enhance the optothermal trapping of other particles. This trapping phenomenon is the net result of thermophoresis and a convective flow caused by localized heating. The heating is due to the conversion of absorbed photons into heat at GNR’s longitudinal surface plasmon resonance (LSPR) wavelength. First, we investigated the optothermal trapping of GNRs at their LSPR wavelength on the glass surface with as low as 0.5 mW laser power. The trapping range was observed to be larger than a typical field of view, e.g. 210 μm × 210 μm here. Second, by adjusting the distance between the laser focus and the glass surface, ring patterns of GNRs on the glass surface were obtained. These patterns could be controlled by the laser power and the numerical aperture of the microscope objective. Moreover, we examined the spectral emission of GNRs under different trapping conditions using the spectral phasor approach to reveal the temperature and association status of GNRs. Our study will help understanding manipulation of flows in solution and in biological systems that can be applied in future investigations of GNR-induced heating and flows. PMID:28355163

Staged Z-pinch for the production of high-flux neutrons and net energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wessel, Frank J.; Rahman, Hafiz Ur; Rostoker, Norman

A fusible target is embedded in a high Z liner, ohmically heated and then shock wave heated by implosion of an enveloping high Z liner. The target is adiabatically heated by compression, fusibly ignited and charged-particle heated as it is being ignited. A shock front forms as the liner implodes which shock front detaches from the more slowly moving liner, collides with the outer surface of the target, accelerates inward, rapidly heating the target, adiabatically compressing the target and liner and amplifying the current to converge the liner mass toward a central axis thereby compressing the target to a fusionmore » condition when it begins to ignite and produce charged particles. The charged particles are trapped in a large magnetic field surrounding the target. The energy of the charged particles is deposited into the target to further heat the target to produce an energy gain.« less

System for rapid biohydrogen phenotypic screening of microorganisms using a chemochromic sensor

DOEpatents

Seibert, Michael; Benson, David K.; Flynn, Timothy Michael

2002-01-01

Provided is a system for identifying a hydrogen gas producing organism. The system includes a sensor film having a first layer comprising a transition metal oxide or oxysalt and a second layer comprising a hydrogen-dissociative catalyst metal, the first and second layers having an inner and an outer surface wherein the inner surface of the second layer is deposited on the outer surface of the first layer, and a substrate adjacent to the outer surface of the second layer, the organism isolated on the substrate.

Method and apparatus for rapid biohydrogen phenotypic screening of microorganisms using a chemochromic sensor

DOEpatents

Seibert, Michael; Benson, David K.; Flynn, Timothy Michael

2001-01-01

The invention provides an assay system for identifying a hydrogen-gas-producing organism, including a sensor film having a first layer comprising a transition metal oxide or oxysalt and a second layer comprising hydrogen-dissociative catalyst metal, the first and second layers having an inner and an outer surface wherein the inner surface of the second layer is deposited on the outer surface of the first layer, and a substrate disposed proximally to the outer surface of the second layer, the organism being isolated on the substrate.

Effects of temperature and surface orientation on migration behaviours of helium atoms near tungsten surfaces

NASA Astrophysics Data System (ADS)

Wang, Xiaoshuang; Wu, Zhangwen; Hou, Qing

2015-10-01

Molecular dynamics simulations were performed to study the dependence of migration behaviours of single helium atoms near tungsten surfaces on the surface orientation and temperature. For W{100} and W{110} surfaces, He atoms can quickly escape out near the surface without accumulation even at a temperature of 400 K. The behaviours of helium atoms can be well-described by the theory of continuous diffusion of particles in a semi-infinite medium. For a W{111} surface, the situation is complex. Different types of trap mutations occur within the neighbouring region of the W{111} surface. The trap mutations hinder the escape of He atoms, resulting in their accumulation. The probability of a He atom escaping into vacuum from a trap mutation depends on the type of the trap mutation, and the occurrence probabilities of the different types of trap mutations are dependent on the temperature. This finding suggests that the escape rate of He atoms on the W{111} surface does not show a monotonic dependence on temperature. For instance, the escape rate at T = 1500 K is lower than the rate at T = 1100 K. Our results are useful for understanding the structural evolution and He release on tungsten surfaces and for designing models in other simulation methods beyond molecular dynamics.

Long-Lived Glass Mirrors For Outer Space

NASA Technical Reports Server (NTRS)

Bouquet, Frank L.; Maag, Carl R.; Heggen, Philip M.

1988-01-01

Paper summarizes available knowledge about glass mirrors for use in outer space. Strengths and weaknesses of various types of first and second reflective surfaces identified. Second-surface glass mirrors used in outer space designed to different criteria more stringent for terrestrial mirrors. Protons, electrons, cosmic rays, meteorites, and orbiting space debris affect longevities of components. Contamination also factor in space.

Auto-positioning ultrasonic transducer system

NASA Technical Reports Server (NTRS)

Buchanan, Randy K. (Inventor)

2010-01-01

An ultrasonic transducer apparatus and process for determining the optimal transducer position for flow measurement along a conduit outer surface. The apparatus includes a transmitting transducer for transmitting an ultrasonic signal, said transducer affixed to a conduit outer surface; a guide rail attached to a receiving transducer for guiding movement of a receiving transducer along the conduit outer surface, wherein the receiving transducer receives an ultrasonic signal from the transmitting transducer and sends a signal to a data acquisition system; and a motor for moving the receiving transducer along the guide rail, wherein the motor is controlled by a controller. The method includes affixing a transmitting transducer to an outer surface of a conduit; moving a receiving transducer on the conduit outer surface, wherein the receiving transducer is moved along a guide rail by a motor; transmitting an ultrasonic signal from the transmitting transducer that is received by the receiving transducer; communicating the signal received by the receiving transducer to a data acquisition and control system; and repeating the moving, transmitting, and communicating along a length of the conduit.

EXTERNAL PHOTOEVAPORATION OF THE SOLAR NEBULA: JUPITER's NOBLE GAS ENRICHMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monga, Nikhil; Desch, Steven

We present a model explaining the elemental enrichments in Jupiter's atmosphere, particularly the noble gases Ar, Kr, and Xe. While He, Ne, and O are depleted, seven other elements show similar enrichments (∼3 times solar, relative to H). Being volatile, Ar is difficult to fractionate from H{sub 2}. We argue that external photoevaporation by far-ultraviolet (FUV) radiation from nearby massive stars removed H{sub 2}, He, and Ne from the solar nebula, but Ar and other species were retained because photoevaporation occurred at large heliocentric distances where temperatures were cold enough (≲ 30 K) to trap them in amorphous water ice. Asmore » the solar nebula lost H, it became relatively and uniformly enriched in other species. Our model improves on the similar model of Guillot and Hueso. We recognize that cold temperatures alone do not trap volatiles; continuous water vapor production is also necessary. We demonstrate that FUV fluxes that photoevaporated the disk generated sufficient water vapor in regions ≲ 30 K to trap gas-phase species in amorphous water ice in solar proportions. We find more efficient chemical fractionation in the outer disk: whereas the model of Guillot and Hueso predicts a factor of three enrichment when only <2% of the disk mass remains, we find the same enrichments when 30% of the disk mass remains. Finally, we predict the presence of ∼0.1 M {sub ⊕} of water vapor in the outer solar nebula and protoplanetary disks in H II regions.« less

High-fidelity operations in microfabricated surface ion traps

NASA Astrophysics Data System (ADS)

Maunz, Peter

2017-04-01

Trapped ion systems can be used to implement quantum computation as well as quantum simulation. To scale these systems to the number of qubits required to solve interesting problems in quantum chemistry or solid state physics, the use of large multi-zone ion traps has been proposed. Microfabrication enables the realization of surface electrode ion traps with complex electrode structures. While these traps may enable the scaling of trapped ion quantum information processing (QIP), microfabricated ion traps also pose several technical challenges. Here, we present Sandia's trap fabrication capabilities and characterize trap properties and shuttling operations in our most recent high optical access trap (HOA-2). To demonstrate the viability of Sandia's microfabricated ion traps for QIP we realize robust single and two-qubit gates and characterize them using gate set tomography (GST). In this way we are able to demonstrate the first single qubit gates with a diamond norm of less than 1 . 7 ×10-4 , below a rigorous fault tolerance threshold for general noise of 6 . 7 ×10-4. Furthermore, we realize Mølmer-Sørensen two qubit gates with a process fidelity of 99 . 58(6) % also characterized by GST. These results demonstrate the viability of microfabricated surface traps for state of the art quantum information processing demonstrations. This research was funded, in part, by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA).

Hot gas path component cooling system having a particle collection chamber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miranda, Carlos Miguel; Lacy, Benjamin Paul

A cooling system for a hot gas path component includes a substrate having an outer surface and an inner surface. The inner surface defines at least one interior space. A passage is formed in the substrate between the outer surface and the inner surface. An access passage is formed in the substrate and extends from the outer surface to the inner space. The access passage is formed at a first acute angle to the passage and includes a particle collection chamber. The access passage is configured to channel a cooling fluid to the passage. Furthermore, the passage is configured tomore » channel the cooling fluid therethrough to cool the substrate.« less

Magnetic pumping of particles in the outer Jovian magnetosphere

NASA Technical Reports Server (NTRS)

Borovsky, J. E.

1980-01-01

The mechanism of magnetic pumping consists of two processes, the adiabatic motion of charged particles in a time varying magnetic field and their pitch-angle diffusion. The result is a systematic increase in the energy of charged particles trapped in mirror (and particularly, magnetospheric) magnetic fields. A numerical model of the mechanism is constructed, compared with analytic theory where possible, and, through elementary exercises, is used to predict the consequences of the process for cases that are not tractable by analytical means. For energy dependent pitch angle diffusion rates, characteristic 'two temperature' distributions are produced. Application of the model to the outer Jovian magnetosphere shows that beyond 20 Jupiter radii in the outer magnetosphere, particles may be magnetically pumped to energies of the order of 1 - 2 MeV. Two temperature distribution functions with "break points" at 1 - 4 KeV for electrons and 8 - 35 KeV for ions are predicted.

Annular vortex combustor

DOEpatents

Nieh, Sen; Fu, Tim T.

1992-01-01

An apparatus for burning coal water fuel, dry ultrafine coal, pulverized l and other liquid and gaseous fuels including a vertically extending outer wall and an inner, vertically extending cylinder located concentrically within the outer wall, the annnular space between the outer wall and the inner cylinder defining a combustion chamber and the all space within the inner cylinder defining an exhaust chamber. Fuel and atomizing air are injected tangentially near the bottom of the combustion chamber and secondary air is introduced at selected points along the length of the combustion chamber. Combustion occurs along the spiral flow path in the combustion chamber and the combined effects of centrifugal, gravitational and aerodynamic forces cause particles of masses or sizes greater than the threshold to be trapped in a stratified manner until completely burned out. Remaining ash particles are then small enough to be entrained by the flue gas and exit the system via the exhaust chamber in the opposite direction.

Sprayed skin turbine component

DOEpatents

Allen, David B

2013-06-04

Fabricating a turbine component (50) by casting a core structure (30), forming an array of pits (24) in an outer surface (32) of the core structure, depositing a transient liquid phase (TLP) material (40) on the outer surface of the core structure, the TLP containing a melting-point depressant, depositing a skin (42) on the outer surface of the core structure over the TLP material, and heating the assembly, thus forming both a diffusion bond and a mechanical interlock between the skin and the core structure. The heating diffuses the melting-point depressant away from the interface. Subsurface cooling channels (35) may be formed by forming grooves (34) in the outer surface of the core structure, filling the grooves with a fugitive filler (36), depositing and bonding the skin (42), then removing the fugitive material.

Telescopic nanotube device for hot nanolithography

DOEpatents

Popescu, Adrian; Woods, Lilia M

2014-12-30

A device for maintaining a constant tip-surface distance for producing nanolithography patterns on a surface using a telescopic nanotube for hot nanolithography. An outer nanotube is attached to an AFM cantilever opposite a support end. An inner nanotube is telescopically disposed within the outer nanotube. The tip of the inner nanotube is heated to a sufficiently high temperature and brought in the vicinity of the surface. Heat is transmitted to the surface for thermal imprinting. Because the inner tube moves telescopically along the outer nanotube axis, a tip-surface distance is maintained constant due to the vdW force interaction, which in turn eliminates the need of an active feedback loop.

Liquid-Sensing Probe and Methods for Using the Same

NASA Technical Reports Server (NTRS)

Haberbusch, Mark S. (Inventor); Ickes, Jacob C. (Inventor); Thurn, Adam (Inventor); Lawless, Branden J. (Inventor)

2014-01-01

A sensor assembly includes a main body, a sensor, and a filler. The main body includes an outer surface having a continuously-variable radius of curvature in at least one portion. A sensor in thermal communication with a region of that surface having relatively low radius of curvature is disposed in the assembly recessed from the outer surface. Liquid droplets adhered to the outer surface in this region tend to migrate to a distant location having a higher radius of curvature. The main body has low thermal conductivity. The filler has a relatively higher thermal conductivity and, in embodiments, fills an opening in the outer surface of the main body, providing a thermally-conductive pathway between the sensor and the surrounding environment via the opening. A probe having a plurality of such sensors, and methods of detecting the presence of liquid and phase transitions in a predetermined space are also disclosed.

Film cooling air pocket in a closed loop cooled airfoil

DOEpatents

Yu, Yufeng Phillip; Itzel, Gary Michael; Osgood, Sarah Jane; Bagepalli, Radhakrishna; Webbon, Waylon Willard; Burdgick, Steven Sebastian

2002-01-01

Turbine stator vane segments have radially inner and outer walls with vanes extending between them. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. To provide for air film cooing of select portions of the airfoil outer surface, at least one air pocket is defined on a wall of at least one of the cavities. Each air pocket is substantially closed with respect to the cooling medium in the cavity and cooling air pumped to the air pocket flows through outlet apertures in the wall of the airfoil to cool the same.

How to catch more prey with less effective traps: explaining the evolution of temporarily inactive traps in carnivorous pitcher plants.

PubMed

Bauer, Ulrike; Federle, Walter; Seidel, Hannes; Grafe, T Ulmar; Ioannou, Christos C

2015-02-22

Carnivorous Nepenthes pitcher plants capture arthropods with specialized slippery surfaces. The key trapping surface, the pitcher rim (peristome), is highly slippery when wetted by rain, nectar or condensation, but not when dry. As natural selection should favour adaptations that maximize prey intake, the evolution of temporarily inactive traps seems paradoxical. Here, we show that intermittent trap deactivation promotes 'batch captures' of ants. Prey surveys revealed that N. rafflesiana pitchers sporadically capture large numbers of ants from the same species. Continuous experimental wetting of the peristome increased the number of non-recruiting prey, but decreased the number of captured ants and shifted their trapping mode from batch to individual capture events. Ant recruitment was also lower to continuously wetted pitchers. Our experimental data fit a simple model that predicts that intermittent, wetness-based trap activation should allow safe access for 'scout' ants under dry conditions, thereby promoting recruitment and ultimately higher prey numbers. The peristome trapping mechanism may therefore represent an adaptation for capturing ants. The relatively rare batch capture events may particularly benefit larger plants with many pitchers. This explains why young plants of many Nepenthes species additionally employ wetness-independent, waxy trapping surfaces.

Characterization and Fabrication of High k dielectric-High Mobility Channel Transistors

NASA Astrophysics Data System (ADS)

Sun, Xiao

As the conventional scaling of Si-based MOSFETs would bring negligible or even negative merits for IC's beyond the 7-nm CMOS technology node, many perceive the use of high-mobility channels to be one of the most likely principle changes, in order to achieve higher performance and lower power. However, interface and oxide traps have become a major obstacle for high-mobility semiconductors (such as Ge, InGaAs, GaSb, GaN...) to replace Si CMOS technology. In this thesis, the distinct properties of the traps in the high-k dielectric/high-mobility substrate system is discussed, as well as the challenges to characterize and passivate them. By modifying certain conventional gate admittance methods, both the fast and slow traps in Ge MOS gate stacks is investigated. In addition, a novel ac-transconductance method originated at Yale is introduced and demonstrated with several advanced transistors provided by collaborating groups, such as ultra-thin-body & box SO1 MOSFETs (CEA-LETI), InGaAs MOSFETs (IMEC, UT Austin, Purdue), and GaN MOS-HEMT (MIT). By use of the aforementioned characterization techniques, several effective passivation techniques on high mobility substrates (Ge, InGaAs, GaSb, GeSn, etc.) are evaluated, including a novel Ba sub-monolayer passivation of Ge surface. The key factors that need to be considered in passivating high mobility substrates are revealed. The techniques that we have established for characterizing traps in advanced field-effect transistors, as well as the knowledge gained about these traps by the use of these techniques, have been applied to the study of ionizing radiation effects in high-mobility-channel transistors, because it is very important to understand such effects as these devices are likely to be exposed to radiation-harsh environments, such as in outer space, nuclear plants, and during X-ray or UHV lithography. In this thesis, the total ionizing dose (TD) radiation effects of InGaAs-based MOSFETs and GaN-based MOS-HEMT are studied, and the results help to reveal the underlying mechanisms and inspire ideas for minimizing the TID radiation effects.

Location Of Hole And Electron Traps On Nanocrystalline Anatase TiO2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mercado, Candy C.; Knorr, Fritz J.; McHale, Jeanne L.

2012-05-17

The defect photoluminescence from TiO2 nanoparticles in the anatase phase is reported for nanosheets which expose predominantly (001) surfaces, and compared to that from conventional anatase nanoparticles which expose mostly (101) surfaces. Also reported is the weak defect photoluminescence of TiO2 nanotubes, which we find using electron back-scattered diffraction to consist of walls which expose (110) and (100) facets. The nanotubes exhibit photoluminescence that is blue-shifted and much weaker than that from conventional TiO2 nanoparticles. Despite the preponderance of (001) surfaces in the nanosheet samples, they exhibit photoluminescence similar to that of conventional nanoparticles. We assign the broad visible photoluminescencemore » of anatase nanoparticles to two overlapping distributions: hole trap emission associated with oxygen vacancies on (101) exposed surfaces, which peaks in the green, and a broader emission extending into the red which results from electron traps on under-coordinated titanium atoms, which are prevalent on (001) facets. The results of this study suggest how morphology of TiO2 nanoparticles could be optimized to control the distribution and activity of surface traps. Our results also shed light on the mechanism by which the TiCl4 surface treatment heals traps on anatase and mixed-phase TiO2 films, and reveals distinct differences in the trap-state distributions of TiO2 nanoparticles and nanotubes. The molecular basis for electron and hole traps and their spatial separation on different facets is discussed.« less

A Scalable Microfabricated Ion Trap for Quantum Information Processing

NASA Astrophysics Data System (ADS)

Maunz, Peter; Haltli, Raymond; Hollowell, Andrew; Lobser, Daniel; Mizrahi, Jonathan; Rembetski, John; Resnick, Paul; Sterk, Jonathan D.; Stick, Daniel L.; Blain, Matthew G.

2016-05-01

Trapped Ion Quantum Information Processing (QIP) relies on complex microfabricated trap structures to enable scaling of the number of quantum bits. Building on previous demonstrations of surface-electrode ion traps, we have designed and characterized the Sandia high-optical-access (HOA-2) microfabricated ion trap. This trap features high optical access, high trap frequencies, low heating rates, and negligible charging of dielectric trap components. We have observed trap lifetimes of more than 100h, measured trap heating rates for ytterbium of less than 40quanta/s, and demonstrated shuttling of ions from a slotted to an above surface region and through a Y-junction. Furthermore, we summarize demonstrations of high-fidelity single and two-qubit gates realized in this trap. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000. This work was supported by the Intelligence Advanced Research Projects Activity (IARPA).

Difference in radiocarbon ages of carbonized material from the inner and outer surfaces of pottery from a wetland archaeological site.

PubMed

Miyata, Yoshiki; Minami, Masayo; Onbe, Shin; Sakamoto, Minoru; Matsuzaki, Hiroyuki; Nakamura, Toshio; Imamura, Mineo

2011-01-01

AMS (Accelerator Mass Spectrometry) radiocarbon dates for eight potsherds from a single piece of pottery from a wetland archaeological site indicated that charred material from the inner pottery surfaces (5052 ± 12 BP; N = 5) is about 90 (14)C years older than that from the outer surfaces (4961 ± 22 BP; N = 7). We considered three possible causes of this difference: the old wood effect, reservoir effects, and diagenesis. We concluded that differences in the radiocarbon ages between materials from the inner and outer surfaces of the same pot were caused either by the freshwater reservoir effect or by diagenesis. Moreover, we found that the radiocarbon ages of carbonized material on outer surfaces (soot) of pottery from other wetland archaeological sites were the same as the ages of material on inner surfaces (charred food) of the same pot within error, suggesting absence of freshwater reservoir effect or diagenesis.

Energy dependence of the trapping of uranium atoms by aluminum oxide surfaces

NASA Technical Reports Server (NTRS)

Librecht, K. G.

1979-01-01

The energy dependence of the trapping probability for sputtered U-235 atoms striking an oxidized aluminum collector surface at energies between 1 eV and 184 eV was measured. At the lowest energies, approximately 10% of the uranium atoms are not trapped, while above 10 eV essentially all of them stick. Trapping probabilities averaged over the sputtered energy distribution for uranium incident on gold and mica are also presented.

Electrostatic particle trap for ion beam sputter deposition

DOEpatents

Vernon, Stephen P.; Burkhart, Scott C.

2002-01-01

A method and apparatus for the interception and trapping of or reflection of charged particulate matter generated in ion beam sputter deposition. The apparatus involves an electrostatic particle trap which generates electrostatic fields in the vicinity of the substrate on which target material is being deposited. The electrostatic particle trap consists of an array of electrode surfaces, each maintained at an electrostatic potential, and with their surfaces parallel or perpendicular to the surface of the substrate. The method involves interception and trapping of or reflection of charged particles achieved by generating electrostatic fields in the vicinity of the substrate, and configuring the fields to force the charged particulate material away from the substrate. The electrostatic charged particle trap enables prevention of charged particles from being deposited on the substrate thereby enabling the deposition of extremely low defect density films, such as required for reflective masks of an extreme ultraviolet lithography (EUVL) system.

Evaluation of Trapped Radiation Model Uncertainties for Spacecraft Design

NASA Technical Reports Server (NTRS)

Armstrong, T. W.; Colborn, B. L.

2000-01-01

The standard AP8 and AE8 models for predicting trapped proton and electron environments have been compared with several sets of flight data to evaluate model uncertainties. Model comparisons are made with flux, dose, and activation measurements made on various U.S. low-Earth orbit satellites (APEX, CRRES, DMSP, LDEF, NOAA) and Space Shuttle flights, on Russian satellites (Photon-8, Cosmos-1887, Cosmos-2044), and on the Russian Mir Space Station. This report gives a summary of the model-data comparisons-detailed results are given in a companion report. Results from the model comparisons with flic,ht data show, for example, the AP8 model underpredicts the trapped proton flux at low altitudes by a factor of about two (independent of proton energy and solar cycle conditions), and that the AE8 model overpredicts the flux in the outer electron belt by an order of magnitude or more.

Evaluation of Trapped Radiation Model Uncertainties for Spacecraft Design

NASA Technical Reports Server (NTRS)

Armstrong, T. W.; Colborn, B. L.

2000-01-01

The standard AP8 and AE8 models for predicting trapped proton and electron environments have been compared with several sets of flight data to evaluate model uncertainties. Model comparisons are made with flux, dose, and activation measurements made on various U.S. low-Earth orbit satellites (APEX, CRRES, DMSP. LDEF, NOAA) and Space Shuttle flights, on Russian satellites (Photon-8, Cosmos-1887, Cosmos-2044), and on the Russian Mir space station. This report gives a summary of the model-data given in a companion report. Results from the model comparisons with flight data show, for example, that the AP8 model underpredicts the trapped proton flux at low altitudes by a factor of about two (independent of proton energy and solar cycle conditions), and that the AE8 model overpredict the flux in the outer electron belt be an order of magnitude or more.

Excitation of Non-Axisymmetric g-MOde Oscillations by Corotation Resonance in Thin Relativistic Disks

NASA Astrophysics Data System (ADS)

Kato, Shoji

2002-02-01

Various modes of oscillations are trapped in the inner region of geometrically thin relativistic disks. Among these oscillations, non-axisymmetric g-mode oscillations have been less studied compared with other modes of oscillations. The modes are, however, interesting since a corotation resonance appears in the trapped region. We mathematically examine whether the modes can be excited by the effects of the corotation resonance. This examination is made under an assumption that the inner and outer Lindblad radii are sufficiently separated in the opposite directions from the corotation radius. The results of analyses suggest that the waves are excited by the corotation resonance. The presence of the excitation suggests that the non-axisymmetric trapped g-mode oscillations are one of possible candidates for the quasi-periodic oscillations of a few hundred to kHz observed in some X-ray sources.

It's a Trap! A Review of MOMA and Other Ion Traps in Space or Under Development

NASA Technical Reports Server (NTRS)

Arevalo, R., Jr.; Brinckerhoff, W. B.; Mahaffy, P. R.; van Amerom, F. H. W.; Danell, R. M.; Pinnick, V. T.; Li, X.; Hovmand, L.; Getty, S. A.; Goesmann, F.;

Convection of Plasmaspheric Plasma into the Outer Magnetosphere and Boundary Layer Region: Initial Results

NASA Technical Reports Server (NTRS)

Ober, Daniel M.; Horwitz, J. L.

1998-01-01

We present initial results on the modeling of the circulation of plasmaspheric-origin plasma into the outer magnetosphere and low-latitude boundary layer (LLBL), using a dynamic global core plasma model (DGCPM). The DGCPM includes the influences of spatially and temporally varying convection and refilling processes to calculate the equatorial core plasma density distribution throughout the magnetosphere. We have developed an initial description of the electric and magnetic field structures in the outer magnetosphere region. The purpose of this paper is to examine both the losses of plasmaspheric-origin plasma into the magnetopause boundary layer and the convection of this plasma that remains trapped on closed magnetic field lines. For the LLBL electric and magnetic structures we have adopted here, the plasmaspheric plasma reaching the outer magnetosphere is diverted anti-sunward primarily along the dusk flank. These plasmas reach X= -15 R(sub E) in the LLBL approximately 3.2 hours after the initial enhancement of convection and continues to populate the LLBL for 12 hours as the convection electric field diminishes.

Correlation between border traps and exposed surface properties in gate recessed normally-off Al2O3/GaN MOSFET

NASA Astrophysics Data System (ADS)

Yin, Ruiyuan; Li, Yue; Sun, Yu; Wen, Cheng P.; Hao, Yilong; Wang, Maojun

2018-06-01

We report the effect of the gate recess process and the surface of as-etched GaN on the gate oxide quality and first reveal the correlation between border traps and exposed surface properties in normally-off Al2O3/GaN MOSFET. The inductively coupled plasma (ICP) dry etching gate recess with large damage presents a rough and active surface that is prone to form detrimental GaxO validated by atomic force microscopy and X-ray photoelectron spectroscopy. Lower drain current noise spectral density of the 1/f form and less dispersive ac transconductance are observed in GaN MOSFETs fabricated with oxygen assisted wet etching compared with devices based on ICP dry etching. One decade lower density of border traps is extracted in devices with wet etching according to the carrier number fluctuation model, which is consistent with the result from the ac transconductance method. Both methods show that the density of border traps is skewed towards the interface, indicating that GaxO is of higher trap density than the bulk gate oxide. GaxO located close to the interface is the major location of border traps. The damage-free oxidation assisted wet etching gate recess technique presents a relatively smooth and stable surface, resulting in lower border trap density, which would lead to better MOS channel quality and improved device reliability.

No barrier to emergence of bathyal king crabs on the Antarctic shelf.

PubMed

Aronson, Richard B; Smith, Kathryn E; Vos, Stephanie C; McClintock, James B; Amsler, Margaret O; Moksnes, Per-Olav; Ellis, Daniel S; Kaeli, Jeffrey; Singh, Hanumant; Bailey, John W; Schiferl, Jessica C; van Woesik, Robert; Martin, Michael A; Steffel, Brittan V; Deal, Michelle E; Lazarus, Steven M; Havenhand, Jonathan N; Swalethorp, Rasmus; Kjellerup, Sanne; Thatje, Sven

2015-10-20

Cold-water conditions have excluded durophagous (skeleton-breaking) predators from the Antarctic seafloor for millions of years. Rapidly warming seas off the western Antarctic Peninsula could now facilitate their return to the continental shelf, with profound consequences for the endemic fauna. Among the likely first arrivals are king crabs (Lithodidae), which were discovered recently on the adjacent continental slope. During the austral summer of 2010 ‒ 2011, we used underwater imagery to survey a slope-dwelling population of the lithodid Paralomis birsteini off Marguerite Bay, western Antarctic Peninsula for environmental or trophic impediments to shoreward expansion. The population density averaged ∼ 4.5 individuals × 1,000 m(-2) within a depth range of 1,100 ‒ 1,500 m (overall observed depth range 841-2,266 m). Images of juveniles, discarded molts, and precopulatory behavior, as well as gravid females in a trapping study, suggested a reproductively viable population on the slope. At the time of the survey, there was no thermal barrier to prevent the lithodids from expanding upward and emerging on the outer shelf (400- to 550-m depth); however, near-surface temperatures remained too cold for them to survive in inner-shelf and coastal environments (<200 m). Ambient salinity, composition of the substrate, and the depth distribution of potential predators likewise indicated no barriers to expansion of lithodids onto the outer shelf. Primary food resources for lithodids--echinoderms and mollusks--were abundant on the upper slope (550-800 m) and outer shelf. As sea temperatures continue to rise, lithodids will likely play an increasingly important role in the trophic structure of subtidal communities closer to shore.

No barrier to emergence of bathyal king crabs on the Antarctic shelf

PubMed Central

Aronson, Richard B.; Smith, Kathryn E.; Vos, Stephanie C.; McClintock, James B.; Amsler, Margaret O.; Moksnes, Per-Olav; Ellis, Daniel S.; Kaeli, Jeffrey; Singh, Hanumant; Bailey, John W.; Schiferl, Jessica C.; van Woesik, Robert; Martin, Michael A.; Steffel, Brittan V.; Deal, Michelle E.; Lazarus, Steven M.; Havenhand, Jonathan N.; Swalethorp, Rasmus; Kjellerup, Sanne; Thatje, Sven

2015-01-01

Cold-water conditions have excluded durophagous (skeleton-breaking) predators from the Antarctic seafloor for millions of years. Rapidly warming seas off the western Antarctic Peninsula could now facilitate their return to the continental shelf, with profound consequences for the endemic fauna. Among the likely first arrivals are king crabs (Lithodidae), which were discovered recently on the adjacent continental slope. During the austral summer of 2010‒2011, we used underwater imagery to survey a slope-dwelling population of the lithodid Paralomis birsteini off Marguerite Bay, western Antarctic Peninsula for environmental or trophic impediments to shoreward expansion. The population density averaged ∼4.5 individuals × 1,000 m−2 within a depth range of 1,100‒1,500 m (overall observed depth range 841–2,266 m). Images of juveniles, discarded molts, and precopulatory behavior, as well as gravid females in a trapping study, suggested a reproductively viable population on the slope. At the time of the survey, there was no thermal barrier to prevent the lithodids from expanding upward and emerging on the outer shelf (400- to 550-m depth); however, near-surface temperatures remained too cold for them to survive in inner-shelf and coastal environments (<200 m). Ambient salinity, composition of the substrate, and the depth distribution of potential predators likewise indicated no barriers to expansion of lithodids onto the outer shelf. Primary food resources for lithodids—echinoderms and mollusks—were abundant on the upper slope (550–800 m) and outer shelf. As sea temperatures continue to rise, lithodids will likely play an increasingly important role in the trophic structure of subtidal communities closer to shore. PMID:26417090

Trapping dynamics of xenon on Pt(111)

NASA Astrophysics Data System (ADS)

Arumainayagam, Christopher R.; Madix, Robert J.; Mcmaster, Mark C.; Suzawa, Valerie M.; Tully, John C.

1990-02-01

The dynamics of Xe trapping on Pt(111) was studied using supersonic atomic beam techniques. Initial trapping probabilities ( S0) were measured directly as a function of incident translational energy ( EinT) and angle of incidence (θ i) at a surface temperature ( Tins) 95 K. The initial trapping probability decreases smoothly with increasing ET cosθ i;, rather than ET cos 2θ i, suggesting participation of parallel momentum in the trapping process. Accordingly, the measured initial trapping probability falls off more slowly with increasing incident translational energy than predicted by one-dimensional theories. This finding is in near agreement with previous mean translational energy measurements for Xe desorbing near the Pt(111) surface normal, assuming detailed balance applies. Three-dimensional stochastic classical trajectory calculations presented herein also exhibit the importance of tangential momentum in trapping and satisfactorily reproduce the experimental initial trapping probabilities.

Positive contact, self retaining bearing seals

DOEpatents

Johnson, Bruce H.; Larsen, Lawrence E.; Welch, Edmund F.

1992-05-05

An ultra-low friction bearing including an inner race, an outer race, bearing elements engaged between the inner and outer races and a seal between the inner and outer races is disclosed. The seal includes first and second sealing washers. The first washer has an outer diameter greater than an inner diameter of the outer race and an inner diameter greater than the outer diameter of the inner race. The second washer has an inner diameter less than the outer diameter of the inner race and an outer diameter less than the inner diameter of the outer race. The first washer slidably engages the outer race, the second washer slidably engages the inner race and the washers overlap and slidably engage one another. One of the washers snap fits into its respective inner or outer race while the other washer engages a stepped surface of the other of the inner and outer races. The grooved and stepped surface are offset from one another in a longitudinal direction of the races such that the washers are conically loaded thus providing a seal between the inner and outer races sufficient to prevent lubricant and contaminating particles from passing therethrough. The washers are made from a non-metallic semi-flexible low-modulus material.

Evolving Hořava cosmological horizons

NASA Astrophysics Data System (ADS)

Fathi, Mohsen; Mohseni, Morteza

2016-09-01

Several sets of radially propagating null congruence generators are exploited in order to form 3-dimensional marginally trapped surfaces, referred to as black hole and cosmological apparent horizons in a Hořava universe. Based on this method, we deal with the characteristics of the 2-dimensional space-like spheres of symmetry and the peculiarities of having trapping horizons. Moreover, we apply this method in standard expanding and contracting FLRW cosmological models of a Hořava universe to investigate the conditions under which the extra parameters of the theory may lead to trapped/anti-trapped surfaces both in the future and in the past. We also include the cases of negative time, referred to as the finite past, and discuss the formation of anti-trapped surfaces inside the cosmological apparent horizons.

Turbine vane with high temperature capable skins

DOEpatents

Morrison, Jay A [Oviedo, FL

2012-07-10

A turbine vane assembly includes an airfoil extending between an inner shroud and an outer shroud. The airfoil can include a substructure having an outer peripheral surface. At least a portion of the outer peripheral surface is covered by an external skin. The external skin can be made of a high temperature capable material, such as oxide dispersion strengthened alloys, intermetallic alloys, ceramic matrix composites or refractory alloys. The external skin can be formed, and the airfoil can be subsequently bi-cast around or onto the skin. The skin and the substructure can be attached by a plurality of attachment members extending between the skin and the substructure. The skin can be spaced from the outer peripheral surface of the substructure such that a cavity is formed therebetween. Coolant can be supplied to the cavity. Skins can also be applied to the gas path faces of the inner and outer shrouds.

Dual mode fuel injector with one piece needle valve member

DOEpatents

Lawrence, Keith E.; Hinrichsen, Michael H.; Buckman, Colby

2005-01-18

A fuel injector includes a homogenous charge nozzle outlet set and a conventional nozzle outlet set controlled respectively by inner and outer needle value members. The homogenous charged nozzle outlet set is defined by an outer needle value member that is moveably positioned in an injector body, which defines the conventional nozzle outlet set. The inner needle valve member is positioned in the outer needle valve member. The outer needle valve member is a piece component that includes at least one external guide surface, an external value surface and an internal valve seat.

Article, component, and method of forming an article

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lacy, Benjamin Paul; Itzel, Gary Michael; Kottilingam, Srikanth Chandrudu

An article and method of forming an article are provided. The article includes a body portion separating an inner region and an outer region, an aperture in the body portion, the aperture fluidly connecting the inner region to the outer region, and a conduit extending from an outer surface of the body portion at the aperture and being arranged and disposed to controllably direct fluid from the inner region to the outer region. The method includes providing a body portion separating an inner region and an outer region, providing an aperture in the body portion, and forming a conduit overmore » the aperture, the conduit extending from an outer surface of the body portion and being arranged and disposed to controllably direct fluid from the inner region to the outer region. The article is arranged and disposed for insertion within a hot gas path component.« less

Results from a Test Fixture for button BPM Trapped Mode Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cameron,P.; Bacha, B.; Blednykh, A.

2009-05-04

A variety of measures have been suggested to mitigate the problem of button BPM trapped mode heating. A test fixture, using a combination of commercial-off-the-shelf and custom machined components, was assembled to validate the simulations. We present details of the fixture design, measurement results, and a comparison of the results with the simulations. A brief history of the trapped mode button heating problem and a set of design rules for BPM button optimization are presented elsewhere in these proceedings. Here we present measurements on a test fixture that was assembled to confirm, if possible, a subset of those rules: (1)more » Minimize the trapped mode impedance and the resulting power deposited in this mode by the beam. (2) Maximize the power re-radiated back into the beampipe. (3) Maximize electrical conductivity of the outer circumference of the button and minimize conductivity of the inner circumference of the shell, to shift power deposition from the button to the shell. The problem is then how to extract useful and relevant information from S-parameter measurements of the test fixture.« less

Toward Scalable Ion Traps for Quantum Information Processing

DTIC Science & Technology

2010-01-01

3/033031 Abstract. In this paper, we report the design, fabrication and preliminary testing of a 150 zone ion trap array built in a ‘ surface ...gates [4–6]. We report here on the design, fabrication and preliminary testing of a large array built in a ‘ surface -electrode’ geometry [7, 8] and...report the first transport of atomic ions through a surface -electrode trap junction. Transport of ions through a junction has been demonstrated previously

77 FR 59732 - Airworthiness Directives; Airbus Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-01

... corrosion and rust traces in the lugs and on the bearing outer surface, discovered visually during scheduled... and rust traces in the lugs and on the bearing outer surface of the nose landing gear (NLG) during...

Spherical bearing. [to reduce vibration effects

NASA Technical Reports Server (NTRS)

Myers, W. N.; Hein, L. A. (Inventor)

1978-01-01

A spherical bearing including an inner ball with an opening for receiving a shaft and a spherical outer surface is described. Features of the bearing include: (1) a circular outer race including a plurality of circumferentially spaced sections extending around the inner ball for snugly receiving the inner ball; and (2) a groove extending circumferentially around the race producing a thin wall portion which permits the opposed side portions to flex relative to the ball for maximizing the physical contact between the inner surface of the race and the spherical outer surface of the ball.

How to catch more prey with less effective traps: explaining the evolution of temporarily inactive traps in carnivorous pitcher plants

PubMed Central

Bauer, Ulrike; Federle, Walter; Seidel, Hannes; Grafe, T. Ulmar; Ioannou, Christos C.

2015-01-01

Carnivorous Nepenthes pitcher plants capture arthropods with specialized slippery surfaces. The key trapping surface, the pitcher rim (peristome), is highly slippery when wetted by rain, nectar or condensation, but not when dry. As natural selection should favour adaptations that maximize prey intake, the evolution of temporarily inactive traps seems paradoxical. Here, we show that intermittent trap deactivation promotes ‘batch captures' of ants. Prey surveys revealed that N. rafflesiana pitchers sporadically capture large numbers of ants from the same species. Continuous experimental wetting of the peristome increased the number of non-recruiting prey, but decreased the number of captured ants and shifted their trapping mode from batch to individual capture events. Ant recruitment was also lower to continuously wetted pitchers. Our experimental data fit a simple model that predicts that intermittent, wetness-based trap activation should allow safe access for ‘scout’ ants under dry conditions, thereby promoting recruitment and ultimately higher prey numbers. The peristome trapping mechanism may therefore represent an adaptation for capturing ants. The relatively rare batch capture events may particularly benefit larger plants with many pitchers. This explains why young plants of many Nepenthes species additionally employ wetness-independent, waxy trapping surfaces. PMID:25589604

Optical pumping of deep traps in AlGaN/GaN-on-Si HEMTs using an on-chip Schottky-on-heterojunction light-emitting diode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Baikui; Tang, Xi; Chen, Kevin J., E-mail: eekjchen@ust.hk

2015-03-02

In this work, by using an on-chip integrated Schottky-on-heterojunction light-emitting diode (SoH-LED) which is seamlessly integrated with the AlGaN/GaN high electron mobility transistor (HEMT), we studied the effect of on-chip light illumination on the de-trapping processes of electrons from both surface and bulk traps. Surface trapping was generated by applying OFF-state drain bias stress, while bulk trapping was generated by applying positive substrate bias stress. The de-trapping processes of surface and/or bulk traps were monitored by measuring the recovery of dynamic on-resistance R{sub on} and/or threshold voltage V{sub th} of the HEMT. The results show that the recovery processes ofmore » both dynamic R{sub on} and threshold voltage V{sub th} of the HEMT can be accelerated by the on-chip SoH-LED light illumination, demonstrating the potentiality of on-chip hybrid opto-HEMTs to minimize the influences of traps during dynamic operation of AlGaN/GaN power HEMTs.« less

Analytic Expressions for the Inner-rim Structure of Passively Heated Protoplanetary Disks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ueda, Takahiro; Okuzumi, Satoshi; Flock, Mario, E-mail: t_ueda@geo.titech.ac.jp

We analytically derive the expressions for the structure of the inner region of protoplanetary disks based on the results from the recent hydrodynamical simulations. The inner part of a disk can be divided into four regions: a dust-free region with a gas temperature in the optically thin limit, an optically thin dust halo, an optically thick condensation front, and the classical, optically thick region, in order from the innermost to the outermost. We derive the dust-to-gas mass ratio profile in the dust halo using the fact that partial dust condensation regulates the temperature relative to the dust evaporation temperature. Beyondmore » the dust halo, there is an optically thick condensation front where all the available silicate gas condenses out. The curvature of the condensation surface is determined by the condition that the surface temperature must be nearly equal to the characteristic temperature ∼1200 K. We derive the midplane temperature in the outer two regions using the two-layer approximation, with the additional heating by the condensation front for the outermost region. As a result, the overall temperature profile is step-like, with steep gradients at the borders between the outer three regions. The borders might act as planet traps where the inward migration of planets due to gravitational interaction with the gas disk stops. The temperature at the border between the two outermost regions coincides with the temperature needed to activate magnetorotational instability, suggesting that the inner edge of the dead zone must lie at this border. The radius of the dead zone inner edge predicted from our solution is ∼2–3 times larger than that expected from the classical optically thick temperature.« less

Analytic Expressions for the Inner-rim Structure of Passively Heated Protoplanetary Disks

NASA Astrophysics Data System (ADS)

Ueda, Takahiro; Okuzumi, Satoshi; Flock, Mario

2017-07-01

We analytically derive the expressions for the structure of the inner region of protoplanetary disks based on the results from the recent hydrodynamical simulations. The inner part of a disk can be divided into four regions: a dust-free region with a gas temperature in the optically thin limit, an optically thin dust halo, an optically thick condensation front, and the classical, optically thick region, in order from the innermost to the outermost. We derive the dust-to-gas mass ratio profile in the dust halo using the fact that partial dust condensation regulates the temperature relative to the dust evaporation temperature. Beyond the dust halo, there is an optically thick condensation front where all the available silicate gas condenses out. The curvature of the condensation surface is determined by the condition that the surface temperature must be nearly equal to the characteristic temperature ˜1200 K. We derive the midplane temperature in the outer two regions using the two-layer approximation, with the additional heating by the condensation front for the outermost region. As a result, the overall temperature profile is step-like, with steep gradients at the borders between the outer three regions. The borders might act as planet traps where the inward migration of planets due to gravitational interaction with the gas disk stops. The temperature at the border between the two outermost regions coincides with the temperature needed to activate magnetorotational instability, suggesting that the inner edge of the dead zone must lie at this border. The radius of the dead zone inner edge predicted from our solution is ˜2-3 times larger than that expected from the classical optically thick temperature.

A model of optical trapping cold atoms using a metallic nano wire with surface plasmon effect

NASA Astrophysics Data System (ADS)

Thi Phuong Lan, Nguyen; Thi Nga, Do; Viet, Nguyen Ai

2016-06-01

In this work, we construct a new model of optical trapping cold atoms with a metallic nano wire by using surface plasmon effect generated by strong field of laser beams. Using the skin effect, we send a strong oscillated electromagnetic filed through the surface of a metallic nano wire. The local field generated by evanescent effect creates an effective attractive potential near the surface of metallic nano wires. The consideration of some possible boundary and frequency conditions might lead to non-trivial bound state solution for a cold atom. We discus also the case of the laser reflection optical trap with shell-core design, and compare our model with another recent schemes of cold atom optical traps using optical fibers and carbon nanotubes.

Modelling deuterium release during thermal desorption of D +-irradiated tungsten

NASA Astrophysics Data System (ADS)

Poon, M.; Haasz, A. A.; Davis, J. W.

2008-03-01

Thermal desorption profiles were modelled based on SIMS measurements of implantation profiles and using the multi-trap diffusion code TMAP7 [G.R. Longhurst, TMAP7: Tritium Migration Analysis Program, User Manual, Idaho National Laboratory, INEEL/EXT-04-02352 (2004)]. The thermal desorption profiles were the result of 500 eV/D + irradiations on single crystal tungsten at 300 and 500 K to fluences of 10 22-10 24 D +/m 2. SIMS depth profiling was performed after irradiation to obtain the distribution of trapped D within the top 60 nm of the surface. Thermal desorption spectroscopy (TDS) was performed subsequently to obtain desorption profiles and to extract the total trapped D inventory. The SIMS profiles were calibrated to give D concentrations. To account for the total trapped D inventory measured by TDS, SIMS depth distributions were used in the near-surface (surface to 30 nm), NRA measurements [V.Kh. Alimov, J. Roth, M. Mayer, J. Nucl. Mater. 337-339 (2005) 619] were used in the range 1-7 μm, and a linear drop in the D distribution was assumed in the intermediate sub-surface region (˜30 nm to 1 μm). Traps were assumed to be saturated so that the D distribution also represented the trap distribution. Three trap energies, 1.07 ± 0.03, 1.34 ± 0.03 and 2.1 ± 0.05 eV were required to model the 520, 640 and 900 K desorption peaks, respectively. The 1.34 and 1.07 eV traps correspond to trapping of a first and second D atom at a vacancy, respectively, while the 2.1 eV trap corresponds to atomic D trapping at a void. A fourth trap energy of 0.65 eV was used to fit the 400 K desorption peak observed by Quastel et al. [A.D. Quastel, J.W. Davis, A.A. Haasz, R.G. Macaulay-Newcombe, J. Nucl. Mater. 359 (2006) 8].

Ion traps fabricated in a CMOS foundry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehta, K. K.; Ram, R. J.; Eltony, A. M.

2014-07-28

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

Marginally trapped surfaces and AdS/CFT

NASA Astrophysics Data System (ADS)

Grado-White, Brianna; Marolf, Donald

2018-02-01

It has been proposed that the areas of marginally trapped or anti-trapped surfaces (also known as leaves of holographic screens) may encode some notion of entropy. To connect this to AdS/CFT, we study the case of marginally trapped surfaces anchored to an AdS boundary. We establish that such boundary-anchored leaves lie between the causal and extremal surfaces defined by the anchor and that they have area bounded below by that of the minimal extremal surface. This suggests that the area of any leaf represents a coarse-grained von Neumann entropy for the associated region of the dual CFT. We further demonstrate that the leading area-divergence of a boundary-anchored marginally trapped surface agrees with that for the associated extremal surface, though subleading divergences generally differ. Finally, we generalize an argument of Bousso and Engelhardt to show that holographic screens with all leaves anchored to the same boundary set have leaf-areas that increase monotonically along the screen, and we describe a construction through which this monotonicity can take the more standard form of requiring entropy to increase with boundary time. This construction is related to what one might call future causal holographic information, which in such cases also provides an upper bound on the area of the associated leaves.

Nontypeable Haemophilus influenzae initiates formation of neutrophil extracellular traps.

PubMed

Juneau, Richard A; Pang, Bing; Weimer, Kristin E D; Armbruster, Chelsie E; Swords, W Edward

2011-01-01

Nontypeable Haemophilus influenzae (NTHI) is a leading cause of otitis media infections, which are often chronic and/or recurrent in nature. NTHI and other bacterial species persist in vivo within biofilms during otitis media and other persistent infections. These biofilms have a significant host component that includes neutrophil extracellular traps (NETs). These NETs do not mediate clearance of NTHI, which survives within NET structures by means of specific subpopulations of lipooligosaccharides on the bacterial surface that are determinants of biofilm formation in vitro. In this study, the ability of NTHI and NTHI components to initiate NET formation was examined using an in vitro model system. Both viable and nonviable NTHI strains were shown to promote NET formation, as did preparations of bacterial DNA, outer membrane proteins, and lipooligosaccharide (endotoxin). However, only endotoxin from a parental strain of NTHI exhibited equivalent potency in NET formation to that of NTHI. Additional studies showed that NTHI entrapped within NET structures is resistant to both extracellular killing within NETs and phagocytic killing by incoming neutrophils, due to oligosaccharide moieties within the lipooligosaccharides. Thus, we concluded that NTHI elicits NET formation by means of multiple pathogen-associated molecular patterns (most notably endotoxin) and is highly resistant to killing within NET structures. These data support the conclusion that, for NTHI, formation of NET structures may be a persistence determinant by providing a niche within the middle-ear chamber.

Freeform Deposition Method for Coolant Channel Closeout

NASA Technical Reports Server (NTRS)

Gradl, Paul R. (Inventor); Reynolds, David Christopher (Inventor); Walker, Bryant H. (Inventor)

2017-01-01

A method is provided for fabricating a coolant channel closeout jacket on a structure having coolant channels formed in an outer surface thereof. A line of tangency relative to the outer surface is defined for each point on the outer surface. Linear rows of a metal feedstock are directed towards and deposited on the outer surface of the structure as a beam of weld energy is directed to the metal feedstock so-deposited. A first angle between the metal feedstock so-directed and the line of tangency is maintained in a range of 20-90.degree.. The beam is directed towards a portion of the linear rows such that less than 30% of the cross-sectional area of the beam impinges on a currently-deposited one of the linear rows. A second angle between the beam and the line of tangency is maintained in a range of 5-65 degrees.

Method for adhering a coating to a substrate structure

DOEpatents

Taxacher, Glenn Curtis; Crespo, Andres Garcia; Roberts, III, Herbert Chidsey

2015-02-17

A method for adhering a coating to a substrate structure comprises selecting a substrate structure having an outer surface oriented substantially parallel to a direction of radial stress, modifying the outer surface to provide a textured region having steps to adhere a coating thereto, and applying a coating to extend over at least a portion of the textured region, wherein the steps are oriented substantially perpendicular to the direction of radial stress to resist deformation of the coating relative to the substrate structure. A rotating component comprises a substrate structure having an outer surface oriented substantially parallel to a direction of radial stress. The outer surface defines a textured region having steps to adhere a coating thereto, and a coating extends over at least a portion of the textured region. The steps are oriented substantially perpendicular to the direction of radial stress to resist creep.

Method and system for providing cooling for turbine components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morgan, Victor John; Lacy, Benjamin Paul

2016-08-16

A system for providing cooling for a turbine component that includes an outer surface exposed to combustion gases is provided. A component base includes at least one fluid supply passage coupleable to a source of cooling fluid. At least one feed passage communicates with the at least one fluid supply passage. At least one delivery channel communicates with the at least one feed passage. At least one cover layer covers the at least one feed passage and the at least one delivery channel, defining at least in part the component outer surface. At least one discharge passage extends to themore » outer surface. A diffuser section is defined in at least one of the at least one delivery channel and the at least one discharge passage, such that a fluid channeled through the system is diffused prior to discharge adjacent the outer surface.« less

Evidence for Surface and Subsurface Ice Inside Micro Cold-Traps on Mercury's North Pole

NASA Technical Reports Server (NTRS)

Rubanenko, L.; Mazarico, E.; Neumann, G. A.; Paige, D. A.

2017-01-01

The small obliquity of Mercury causes topographic depressions located near its poles to cast persistent shadows. Many [1, 9, 15] have shown these permanently shadowed regions (PSRs) may trap water ice for geologic time periods inside cold-traps. More recently, direct evidence for the presence of water ice deposits inside craters was remotely sensed in RADAR [5] and visible imagery [3]. Albedo measurements (reflectence at 1064 nm) obtained by the MErcury Space ENviroment GEochemistry and Ranging Laser Altimeter (MLA) found unusually bright and dark areas next to Mercury's north pole [7]. Using a thermal illumination model, Paige et al. [8] found the bright deposits are correlated with surface cold-traps, and the dark deposits are correlated with subsurface cold-traps. They suggested these anomalous deposits were brought to the surface by comets and were processed by the magnetospheric radiation flux, removing hydrogen and mixing C-N-O-S atoms to form a variety of molecules which will darken with time. Here we use a thermal illumination model to find the link between the cold-trap area fraction of a rough surface and its albedo. Using this link and the measurements obtained by MESSENGER we derive a surface and a subsurface ice distribution map on Mercury's north pole below the MESSENGER spatial resolution, approximately 500 m. We find a large fraction of the polar ice on Mercury resides inside micro cold-traps (of scales 10 - 100 m) distributed along the inter-crater terrain.

In situ spectroscopic evidence for neptunium(V)-carbonate inner-sphere and outer-sphere ternary surface complexes on hematite surfaces.

PubMed

Arai, Yuji; Moran, P B; Honeyman, B D; Davis, J A

2007-06-01

Np(V) surface speciation on hematite surfaces at pH 7-9 under pC2 = 10(-3.45) atm was investigated using X-ray absorption spectroscopy (XAS). In situ XAS analyses suggest that bis-carbonato inner-sphere and tris-carbonato outer-sphere ternary surface species coexist at the hematite-water interface at pH 7-8.8, and the fraction of outer-sphere species gradually increases from 27 to 54% with increasing pH from 7 to 8.8. The results suggest that the heretofore unknown Np(V)-carbonato ternary surface species may be important in predicting the fate and transport of Np(V) in the subsurface environment down gradient of high-level nuclear waste respositories.

Regions of tunneling dynamics for few bosons in an optical lattice subjected to a quench of the imposed harmonic trap

NASA Astrophysics Data System (ADS)

Mistakidis, Simeon; Koutentakis, Georgios; Schmelcher, Peter; Theory Group of Fundamental Processes in Quantum Physics Team

2016-05-01

Recent experimental advances have introduced an interplay in the trapping length scales of the lattice and the harmonic confinement. This fact motivates the investigation to prepare atomic gases at certain quantum states by utilizing a composite atomic trap consisting of a lattice potential that is embedded inside an overlying harmonic trap. In the present work, we examine how frequency modulations of the overlying harmonic trap stimulate the dynamics of an 1D few-boson gas. The gas is initially prepared at a highly confined state, and the subsequent dynamics induced by a quench of the harmonic trap frequency to a lower value is examined. It is shown that a non-interacting gas always diffuses to the outer sites. In contrast the response of the interacting system is more involved and is dominated by a resonance, which is induced by the bifurcation of the low-lying eigenstates. Our study reveals that the position of the resonance depends both on the atom number and the interaction coupling, manifesting its many body nature. The corresponding mean field treatment as well as the single-band approximation have been found to be inadequate for the description of the tunneling dynamics in the interacting case. Deutsche Forschungsgemeinschaft, SFB 925 ``Light induced dynamics and control of correlated quantum systems''.

Detection of Campylobacter on the outer surface of retail broiler meat packages and from the exudate within

USDA-ARS?s Scientific Manuscript database

Previous work has suggested that outer surfaces of retail broiler meat packaging may be contaminated with Campylobacter presenting a potential hazard to the consumer through direct transfer or by cross contamination of other products or surfaces. The objectives of this study were to measure the pre...

A Novel Gravito-Optical Surface Trap for Neutral Atoms

NASA Astrophysics Data System (ADS)

Xie, Chun-Xia; Wang, Zhengling; Yin, Jian-Ping

2006-04-01

We propose a novel gravito-optical surface trap (GOST) for neutral atoms based on one-dimensional intensity gradient cooling. The surface optical trap is composed of a blue-detuned reduced semi-Gaussian laser beam (SGB), a far-blue-detuned dark hollow beam and the gravity field. The SGB is produced by the diffraction of a collimated Gaussian laser beam passing through the straight edge of a semi-infinite opaque plate and then is reduced by an imaging lens. We calculate the intensity distribution of the reduced SGB, and study the dynamic process of the SGB intensity-gradient induced Sisyphus cooling for 87Rb atoms by using Monte Carlo simulations. Our study shows that the proposed GOST can be used not only to trap cold atoms loaded from a standard magneto-optical trap, but also to cool the trapped atoms to an equilibrium temperature of 3.47 μK from ~120 μK, even to realize an all-optical two-dimensional Bose-Einstein condensation by using optical-potential evaporative cooling.

10 CFR 71.55 - General requirements for fissile material packages.

Code of Federal Regulations, 2012 CFR

2012-01-01

... the outer surface of the packaging; and (iii) No occurrence of an aperture in the outer surface of the... spaces is prevented following application of the tests in paragraphs (f)(1) and (f)(2) of this section...

Photovoltaic module mounting clip with integral grounding

DOEpatents

Lenox, Carl J.

2008-10-14

An electrically conductive mounting/grounding clip, for use with a photovoltaic assembly of the type having an electrically conductive frame, comprises an electrically conductive body. The body has a central portion and first and second spaced-apart arms extending generally perpendicular to the central portion. Each arm has an outer portion with each outer portion having an outer end. At least one frame surface-disrupting element is at each outer end. The central portion defines a plane with the frame surface-disrupting elements pointing towards the plane. In some examples each arm extends from the central portion at an acute angle to the plane.

Gas insulated transmission line having low inductance intercalated sheath

DOEpatents

Cookson, Alan H.

1978-01-01

A gas insulated transmission line including an outer sheath, an inner conductor disposed within the outer sheath, and an insulating gas between the inner conductor and the outer sheath. The outer sheath comprises an insulating tube having first and second ends, and having interior and exterior surfaces. A first electrically conducting foil is secured to the interior surface of the insulating tube, is spirally wound from one tube end to the second tube end, and has a plurality of overlapping turns. A second electrically conducting foil is secured to the exterior surface of the insulating tube, and is spirally wound in the opposite direction from the first electrically conducting foil. By winding the foils in opposite directions, the inductances within the intercalated sheath will cancel each other out.

Thermal barriers for compartments

DOEpatents

Kreutzer, Cory J.; Lustbader, Jason A.

2017-10-17

An aspect of the present disclosure is a thermal barrier that includes a core layer having a first surface, a second surface, and a first edge, and a first outer layer that includes a third surface and a second edge, where the third surface substantially contacts the first surface, the core layer is configured to minimize conductive heat transfer through the barrier, and the first outer layer is configured to maximize reflection of light away from the barrier.

Investigation of Trap States in AlInN/AlN/GaN Heterostructures by Frequency-Dependent Admittance Analysis

NASA Astrophysics Data System (ADS)

Arslan, Engin; Bütün, Serkan; Şafak, Yasemin; Ozbay, Ekmel

2010-12-01

We present a systematic study on the admittance characterization of surface trap states in unpassivated and SiN x -passivated Al0.83In0.17N/AlN/GaN heterostructures. C- V and G/ ω- V measurements were carried out in the frequency range of 1 kHz to 1 MHz, and an equivalent circuit model was used to analyze the experimental data. A detailed analysis of the frequency-dependent capacitance and conductance data was performed, assuming models in which traps are located at the metal-AlInN surface. The density ( D t) and time constant ( τ t) of the surface trap states have been determined as a function of energy separation from the conduction-band edge ( E c - E t). The D st and τ st values of the surface trap states for the unpassivated samples were found to be D_{{st}} \\cong (4 - 13) × 10^{12} {eV}^{ - 1} {cm}^{ - 2} and τ st ≈ 3 μs to 7 μs, respectively. For the passivated sample, D st decreased to 1.5 × 10^{12} {eV}^{ - 1} {cm}^{ - 2} and τ st to 1.8 μs to 2 μs. The density of surface trap states in Al0.83In0.17N/AlN/GaN heterostructures decreased by approximately one order of magnitude with SiN x passivation, indicating that the SiN x insulator layer between the metal contact and the surface of the Al0.83In0.17N layer can passivate surface states.

Hysteresis in Carbon Nanotube Transistors: Measurement and Analysis of Trap Density, Energy Level, and Spatial Distribution.

PubMed

Park, Rebecca Sejung; Shulaker, Max Marcel; Hills, Gage; Suriyasena Liyanage, Luckshitha; Lee, Seunghyun; Tang, Alvin; Mitra, Subhasish; Wong, H-S Philip

2016-04-26

We present a measurement technique, which we call the Pulsed Time-Domain Measurement, for characterizing hysteresis in carbon nanotube field-effect transistors, and demonstrate its applicability for a broad range of 1D and 2D nanomaterials beyond carbon nanotubes. The Pulsed Time-Domain Measurement enables the quantification (density, energy level, and spatial distribution) of charged traps responsible for hysteresis. A physics-based model of the charge trapping process for a carbon nanotube field-effect transistor is presented and experimentally validated using the Pulsed Time-Domain Measurement. Leveraging this model, we discover a source of traps (surface traps) unique to devices with low-dimensional channels such as carbon nanotubes and nanowires (beyond interface traps which exist in today's silicon field-effect transistors). The different charge trapping mechanisms for interface traps and surface traps are studied based on their temperature dependencies. Through these advances, we are able to quantify the interface trap density for carbon nanotube field-effect transistors (∼3 × 10(13) cm(-2) eV(-1) near midgap), and compare this against a range of previously studied dielectric/semiconductor interfaces.

Effect of organic materials used in the synthesis on the emission from CdSe quantum dots

NASA Astrophysics Data System (ADS)

Lee, Jae-Won; Yang, Ho-Soon; Hong, K. S.; Kim, S. M.

2013-12-01

Quantum-dot nanocrystals have particular optical properties due to the quantum confinement effect and the surface effect. This study focuses on the effect of surface conditions on the emission from quantum dots. The quantum dots prepared with 1-hexadecylamine (HDA) in the synthesis show strong emission while the quantum dots prepared without HDA show weak emission, as well as emission from surface energy traps. The comparison of the X-ray patterns of these two sets of quantum dots reveals that HDA forms a layer on the surface of quantum dot during the synthesis. This surface passivation with a layer of HDA reduces surface energy traps, therefore the emission from surface trap levels is suppressed in the quantum dots synthesized with HDA.

Magnetometric mapping of superconducting RF cavities

NASA Astrophysics Data System (ADS)

Schmitz, B.; Köszegi, J.; Alomari, K.; Kugeler, O.; Knobloch, J.

2018-05-01

A scalable mapping system for superconducting RF (SRF) cavities is presented. Currently, it combines local temperature measurement with 3D magnetic field mapping along the outer surface of the resonator. This allows for the observation of dynamic effects that have an impact on the superconducting properties of a cavity, such as the normal to superconducting phase transition or a quench. The system was developed for a single cell 1.3 GHz TESLA-type cavity, but can be easily adopted to arbitrary other cavity types. A data acquisition rate of 500 Hz for all channels simultaneously (i.e., 2 ms acquisition time for a complete map) and a magnetic field resolution of currently up to 14 mA/m/μ0 = 17 nT have been implemented. While temperature mapping is a well known technique in SRF research, the integration of magnetic field mapping opens the possibility of detailed studies of trapped magnetic flux and its impact on the surface resistance. It is shown that magnetic field sensors based on the anisotropic magnetoresistance effect can be used in the cryogenic environment with improved sensitivity compared to room temperature. Furthermore, examples of first successful combined temperature and magnetic-field maps are presented.

An optical conveyor for molecules.

PubMed

Weinert, Franz M; Braun, Dieter

2009-12-01

Trapping single ions under vacuum allows for precise spectroscopy in atomic physics. The confinement of biological molecules in bulk water is hindered by the lack of comparably strong forces. Molecules have been immobilized to surfaces, however often with detrimental effects on their function. Here, we optically trap molecules by creating the microscale analogue of a conveyor belt: a bidirectional flow is combined with a perpendicular thermophoretic molecule drift. Arranged in a toroidal geometry, the conveyor accumulates a hundredfold excess of 5-base DNA within seconds. The concentrations of the trapped DNA scale exponentially with length, reaching trapping potential depths of 14 kT for 50 bases. The mechanism does not require microfluidics, electrodes, or surface modifications. As a result, the trap can be dynamically relocated. The optical conveyor can be used to enhance diffusion-limited surface reactions, redirect cellular signaling, observe individual biomolecules over a prolonged time, or approach single-molecule chemistry in bulk water.

Two-Scale Ion Meandering Caused by the Polarization Electric Field During Asymmetric Reconnection

NASA Technical Reports Server (NTRS)

Wang, Shan; Chen, Li-Jen; Hesse, Michael; Bessho, Naoki; Gershman, Daniel J.; Dorelli, John; Giles, Barbara L.; Torbert, Roy B.; Pollock, Craig J.; Strangeway, Robert;

Energetic neutral atom emissions from Titan interaction with Saturn's magnetosphere.

PubMed

Mitchell, D G; Brandt, P C; Roelof, E C; Dandouras, J; Krimigis, S M; Mauk, B H

2005-05-13

The Cassini Magnetospheric Imaging Instrument (MIMI) observed the interaction of Saturn's largest moon, Titan, with Saturn's magnetosphere during two close flybys of Titan on 26 October and 13 December 2004. The MIMI Ion and Neutral Camera (INCA) continuously imaged the energetic neutral atoms (ENAs) generated by charge exchange reactions between the energetic, singly ionized trapped magnetospheric ions and the outer atmosphere, or exosphere, of Titan. The images reveal a halo of variable ENA emission about Titan's nearly collisionless outer atmosphere that fades at larger distances as the exospheric density decays exponentially. The altitude of the emissions varies, and they are not symmetrical about the moon, reflecting the complexity of the interactions between Titan's upper atmosphere and Saturn's space environment.

Two-scale ion meandering caused by the polarization electric field during asymmetric reconnection

NASA Astrophysics Data System (ADS)

Wang, Shan; Chen, Li-Jen; Hesse, Michael; Bessho, Naoki; Gershman, Daniel J.; Dorelli, John; Giles, Barbara; Torbert, Roy B.; Pollock, Craig J.; Strangeway, Robert; Ergun, Robert E.; Burch, James L.; Avanov, Levon; Lavraud, Benoit; Moore, Thomas E.; Saito, Yoshifumi

2016-08-01

Ion velocity distribution functions (VDFs) from a particle-in-cell simulation of asymmetric reconnection are investigated to reveal a two-scale structure of the ion diffusion region (IDR). Ions bouncing in the inner IDR are trapped mainly by the electric field normal to the current sheet (N direction), while those reaching the outer IDR are turned back mainly by the magnetic force. The resulting inner layer VDFs have counter-streaming populations along N with decreasing counter-streaming speeds away from the midplane while maintaining the out-of-plane speed, and the outer layer VDFs exhibit crescent shapes toward the out-of-plane direction. Observations of the above VDF features and the normal electric fields provide evidence for the two-scale meandering motion.

Explosives screening on a vehicle surface

DOEpatents

Parmeter, John E.; Brusseau, Charles A.; Davis, Jerry D.; Linker, Kevin L.; Hannum, David W.

2005-02-01

A system for detecting particles on the outer surface of a vehicle has a housing capable of being placed in a test position adjacent to, but not in contact with, a portion of the outer surface of the vehicle. An elongate sealing member is fastened to the housing along a perimeter surrounding the wall, and the elongate sealing member has a contact surface facing away from the wall to contact the outer surface of the vehicle to define a test volume when the wall is in the test position. A gas flow system has at least one gas inlet extending through the wall for providing a gas stream against the surface of the vehicle within the test volume. This gas stream, which preferably is air, dislodges particles from the surface of the vehicle covered by the housing. The gas stream exits the test volume through a gas outlet and particles in the stream are detected.

Surface dimpling on rotating work piece using rotation cutting tool

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhapkar, Rohit Arun; Larsen, Eric Richard

A combined method of machining and applying a surface texture to a work piece and a tool assembly that is capable of machining and applying a surface texture to a work piece are disclosed. The disclosed method includes machining portions of an outer or inner surface of a work piece. The method also includes rotating the work piece in front of a rotating cutting tool and engaging the outer surface of the work piece with the rotating cutting tool to cut dimples in the outer surface of the work piece. The disclosed tool assembly includes a rotating cutting tool coupledmore » to an end of a rotational machining device, such as a lathe. The same tool assembly can be used to both machine the work piece and apply a surface texture to the work piece without unloading the work piece from the tool assembly.« less

Microscopic studies of the fate of charges in organic semiconductors: Scanning Kelvin probe measurements of charge trapping, transport, and electric fields in p- and n-type devices

NASA Astrophysics Data System (ADS)

Smieska, Louisa Marion

Organic semiconductors could have wide-ranging applications in lightweight, efficient electronic circuits. However, several fundamental questions regarding organic electronic device behavior have not yet been fully addressed, including the nature of chemical charge traps, and robust models for injection and transport. Many studies focus on engineering devices through bulk transport measurements, but it is not always possible to infer the microscopic behavior leading to the observed measurements. In this thesis, we present scanning-probe microscope studies of organic semiconductor devices in an effort to connect local properties with local device behavior. First, we study the chemistry of charge trapping in pentacene transistors. Working devices are doped with known pentacene impurities and the extent of charge trap formation is mapped across the transistor channel. Trap-clearing spectroscopy is employed to measure an excitation of the pentacene charge trap species, enabling identification of the degradationrelated chemical trap in pentacene. Second, we examine transport and trapping in peryelene diimide (PDI) transistors. Local mobilities are extracted from surface potential profiles across a transistor channel, and charge injection kinetics are found to be highly sensitive to electrode cleanliness. Trap-clearing spectra generally resemble PDI absorption spectra, but one derivative yields evidence indicating variation in trap-clearing mechanisms for different surface chemistries. Trap formation rates are measured and found to be independent of surface chemistry, contradicting a proposed silanol trapping mechanism. Finally, we develop a variation of scanning Kelvin probe microscopy that enables measurement of electric fields through a position modulation. This method avoids taking a numeric derivative of potential, which can introduce high-frequency noise into the electric field signal. Preliminary data is presented, and the theoretical basis for electric field noise in both methods is examined.

Outer Membrane Targeting of Passenger Proteins by the Vacuolating Cytotoxin Autotransporter of Helicobacter pylori

PubMed Central

Fischer, Wolfgang; Buhrdorf, Renate; Gerland, Elke; Haas, Rainer

2001-01-01

Helicobacter pylori produces a number of proteins associated with the outer membrane, including adhesins and the vacuolating cytotoxin. These proteins are supposed to integrate into the outer membrane by β-barrel structures, characteristic of the family of autotransporter proteins. By using the SOMPES (shuttle vector-based outer membrane protein expression) system for outer membrane protein production, we were able to functionally express in H. pylori the cholera toxin B subunit genetically fused to the C-terminal VacA domain. We demonstrate that the fusion protein is translocated to the H. pylori outer membrane and that the CtxB domain is exposed on the H. pylori surface. Thus, we provide the first experimental evidence that the C-terminal β-domain of VacA can transport a foreign passenger protein to the H. pylori surface and hence acts as a functional autotransporter. PMID:11598049

Permeation absorption sampler with multiple detection

DOEpatents

Zaromb, Solomon

1990-01-01

A system for detecting analytes in air or aqueous systems includes a permeation absorption preconcentrator sampler for the analytes and analyte detectors. The preconcentrator has an inner fluid-permeable container into which a charge of analyte-sorbing liquid is intermittently injected, and a fluid-impermeable outer container. The sample is passed through the outer container and around the inner container for trapping and preconcentrating the analyte in the sorbing liquid. The analyte can be detected photometrically by injecting with the sorbing material a reagent which reacts with the analyte to produce a characteristic color or fluorescence which is detected by illuminating the contents of the inner container with a light source and measuring the absorbed or emitted light, or by producing a characteristic chemiluminescence which can be detected by a suitable light sensor. The analyte can also be detected amperometrically. Multiple inner containers may be provided into which a plurality of sorbing liquids are respectively introduced for simultaneously detecting different analytes. Baffles may be provided in the outer container. A calibration technique is disclosed.

High concentration effects of neutral-potential-well interface traps on recombination dc current-voltage lineshape in metal-oxide-silicon transistors

NASA Astrophysics Data System (ADS)

Chen, Zuhui; Jie, Bin B.; Sah, Chih-Tang

2008-11-01

Steady-state Shockley-Read-Hall kinetics is employed to explore the high concentration effect of neutral-potential-well interface traps on the electron-hole recombination direct-current current-voltage (R-DCIV) properties in metal-oxide-silicon field-effect transistors. Extensive calculations include device parameter variations in neutral-trapping-potential-well electron interface-trap density NET (charge states 0 and -1), dopant impurity concentration PIM, oxide thickness Xox, forward source/drain junction bias VPN, and transistor temperature T. It shows significant distortion of the R-DCIV lineshape by the high concentrations of the interface traps. The result suggests that the lineshape distortion observed in past experiments, previously attributed to spatial variation in surface impurity concentration and energy distribution of interface traps in the silicon energy gap, can also arise from interface-trap concentration along surface channel region.

A sheet metal forming simulation of automotive outer panels considering the behavior of air in die cavity

NASA Astrophysics Data System (ADS)

Choi, Kwang Yong; Kim, Yun Chang; Choi, Hee Kwan; Kang, Chul Ho; Kim, Heon Young

2013-12-01

During a sheet metal forming process of automotive outer panels, the air trapped between a blank sheet and a die tool can become highly compressed, ultimately influencing the blank deformation and the press force. To prevent this problem, vent holes are drilled into die tools and needs several tens to hundreds according to the model size. The design and the drilling of vent holes are based on expert's experience and try-out result and thus the process can be one of reasons increasing development cycle. Therefore the study on the size, the number, and the position of vent holes is demanded for reducing development cycle, but there is no simulation technology for analyzing forming defects, making numerical sheet metal forming process simulations that incorporate the fluid dynamics of air. This study presents a sheet metal forming simulation of automotive outer panels (a roof and a body side outer) that simultaneously simulates the behavior of air in a die cavity. Through CAE results, the effect of air behavior and vent holes to blank deformation was analyzed. For this study, the commercial software PAM-STAMP{trade mark, serif} and PAM-SAFE{trade mark, serif} was used.

Experimental Methods for Trapping Ions Using Microfabricated Surface Ion Traps

PubMed Central

Hong, Seokjun; Lee, Minjae; Kwon, Yeong-Dae; Cho, Dong-il "Dan"; Kim, Taehyun

2017-01-01

Ions trapped in a quadrupole Paul trap have been considered one of the strong physical candidates to implement quantum information processing. This is due to their long coherence time and their capability to manipulate and detect individual quantum bits (qubits). In more recent years, microfabricated surface ion traps have received more attention for large-scale integrated qubit platforms. This paper presents a microfabrication methodology for ion traps using micro-electro-mechanical system (MEMS) technology, including the fabrication method for a 14 µm-thick dielectric layer and metal overhang structures atop the dielectric layer. In addition, an experimental procedure for trapping ytterbium (Yb) ions of isotope 174 (174Yb+) using 369.5 nm, 399 nm, and 935 nm diode lasers is described. These methodologies and procedures involve many scientific and engineering disciplines, and this paper first presents the detailed experimental procedures. The methods discussed in this paper can easily be extended to the trapping of Yb ions of isotope 171 (171Yb+) and to the manipulation of qubits. PMID:28872137

Wedge edge ceramic combustor tile

DOEpatents

Shaffer, J.E.; Holsapple, A.C.

1997-06-10

A multipiece combustor has a portion thereof being made of a plurality of ceramic segments. Each of the plurality of ceramic segments have an outer surface and an inner surface. Each of the plurality of ceramic segments have a generally cylindrical configuration and including a plurality of joints. The joints define joint portions, a first portion defining a surface being skewed to the outer surface and the inner surface. The joint portions have a second portion defining a surface being skewed to the outer surface and the inner surface. The joint portions further include a shoulder formed intermediate the first portion and the second portion. The joints provide a sealing interlocking joint between corresponding ones of the plurality of ceramic segments. Thus, the multipiece combustor having the plurality of ceramic segment with the plurality of joints reduces the physical size of the individual components and the degradation of the surface of the ceramic components in a tensile stress zone is generally eliminated reducing the possibility of catastrophic failures. 7 figs.

Wedge edge ceramic combustor tile

DOEpatents

Shaffer, James E.; Holsapple, Allan C.

1997-01-01

A multipiece combustor has a portion thereof being made of a plurality of ceramic segments. Each of the plurality of ceramic segments have an outer surface and an inner surface. Each of the plurality of ceramic segments have a generally cylindrical configuration and including a plurality of joints. The joints define joint portions, a first portion defining a surface being skewed to the outer surface and the inner surface. The joint portions have a second portion defining a surface being skewed to the outer surface and the inner surface. The joint portions further include a shoulder formed intermediate the first portion and the second portion. The joints provide a sealing interlocking joint between corresponding ones of the plurality of ceramic segments. Thus, the multipiece combustor having the plurality of ceramic segment with the plurality of joints reduces the physical size of the individual components and the degradation of the surface of the ceramic components in a tensile stress zone is generally eliminated reducing the possibility of catastrophic failures.

Density of Trap States and Auger-mediated Electron Trapping in CdTe Quantum-Dot Solids.

PubMed

Boehme, Simon C; Azpiroz, Jon Mikel; Aulin, Yaroslav V; Grozema, Ferdinand C; Vanmaekelbergh, Daniël; Siebbeles, Laurens D A; Infante, Ivan; Houtepen, Arjan J

2015-05-13

Charge trapping is an ubiquitous process in colloidal quantum-dot solids and a major limitation to the efficiency of quantum dot based devices such as solar cells, LEDs, and thermoelectrics. Although empirical approaches led to a reduction of trapping and thereby efficiency enhancements, the exact chemical nature of the trapping mechanism remains largely unidentified. In this study, we determine the density of trap states in CdTe quantum-dot solids both experimentally, using a combination of electrochemical control of the Fermi level with ultrafast transient absorption and time-resolved photoluminescence spectroscopy, and theoretically, via density functional theory calculations. We find a high density of very efficient electron traps centered ∼0.42 eV above the valence band. Electrochemical filling of these traps increases the electron lifetime and the photoluminescence quantum yield by more than an order of magnitude. The trapping rate constant for holes is an order of magnitude lower that for electrons. These observations can be explained by Auger-mediated electron trapping. From density functional theory calculations we infer that the traps are formed by dicoordinated Te atoms at the quantum dot surface. The combination of our unique experimental determination of the density of trap states with the theoretical modeling of the quantum dot surface allows us to identify the trapping mechanism and chemical reaction at play during charge trapping in these quantum dots.

Trapping of diffusing particles by striped cylindrical surfaces. Boundary homogenization approach

PubMed Central

Dagdug, Leonardo; Berezhkovskii, Alexander M.; Skvortsov, Alexei T.

2015-01-01

We study trapping of diffusing particles by a cylindrical surface formed by rolling a flat surface, containing alternating absorbing and reflecting stripes, into a tube. For an arbitrary stripe orientation with respect to the tube axis, this problem is intractable analytically because it requires dealing with non-uniform boundary conditions. To bypass this difficulty, we use a boundary homogenization approach which replaces non-uniform boundary conditions on the tube wall by an effective uniform partially absorbing boundary condition with properly chosen effective trapping rate. We demonstrate that the exact solution for the effective trapping rate, known for a flat, striped surface, works very well when this surface is rolled into a cylindrical tube. This is shown for both internal and external problems, where the particles diffuse inside and outside the striped tube, at three orientations of the stripe direction with respect to the tube axis: (a) perpendicular to the axis, (b) parallel to the axis, and (c) at the angle of π/4 to the axis. PMID:26093574

A new tabanid trap applying a modified concept of the old flypaper: linearly polarising sticky black surfaces as an effective tool to catch polarotactic horseflies.

PubMed

Egri, Ádám; Blahó, Miklós; Száz, Dénes; Barta, András; Kriska, György; Antoni, Györgyi; Horváth, Gábor

2013-06-01

Trapping flies with sticky paper sheets is an ancient method. The classic flypaper has four typical characteristics: (i) its sticky paper is bright (chamois, light yellow or white), (ii) it is strip-shaped, (iii) it hangs vertically, and (iv) it is positioned high (several metres) above ground level. Such flypapers, however, do not trap horseflies (tabanids). There is a great need to kill horseflies with efficient traps because they are vectors of dangerous diseases, and due to their continuous annoyance livestock cannot graze, horses cannot be ridden, and meat and milk production from cattle is drastically reduced. Based on earlier findings on the positive polarotaxis (attraction to linearly polarised light) in tabanid flies and modifying the concept of the old flypaper, we constructed a new horsefly trap called "horseflypaper". In four field experiments we showed that the ideal horseflypaper (i) is shiny black, (ii) has an appropriately large (75×75 cm(2)) surface area, (iii) has sticky black vertical and horizontal surfaces in an L-shaped arrangement, and (iv) its horizontal surface should be at ground level for maximum effectiveness. Using imaging polarimetry, we measured the reflection-polarisation characteristics of this new polarisation tabanid trap. The ideal optical and geometrical characteristics of this trap revealed in field experiments are also explained. The horizontal part of the trap captures water-seeking male and female tabanids, while the vertical part catches host-seeking female tabanids. Copyright © 2013 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Efficacy of Fluon conditioning for capturing cerambycid beetles in different trap designs and rersistence on panel traps over time

Treesearch

Elizabeth E. Graham; Therese M. Poland

2012-01-01

Fluon PTFE is a fluoropolymer dispersion applied as a surface conditioner to cross-vane panel traps to enhance trap efficiency for cerambycid beetles. We describe the results of three experiments to further optimize cerambycid traps of different designs and to test the effect of Fluon over time. We tested Fluon with Lindgren funnel and panel traps fitted with either...

Research on stellarator-mirror fission-fusion hybrid

NASA Astrophysics Data System (ADS)

Moiseenko, V. E.; Kotenko, V. G.; Chernitskiy, S. V.; Nemov, V. V.; Ågren, O.; Noack, K.; Kalyuzhnyi, V. N.; Hagnestål, A.; Källne, J.; Voitsenya, V. S.; Garkusha, I. E.

2014-09-01

The development of a stellarator-mirror fission-fusion hybrid concept is reviewed. The hybrid comprises of a fusion neutron source and a powerful sub-critical fast fission reactor core. The aim is the transmutation of spent nuclear fuel and safe fission energy production. In its fusion part, neutrons are generated in deuterium-tritium (D-T) plasma, confined magnetically in a stellarator-type system with an embedded magnetic mirror. Based on kinetic calculations, the energy balance for such a system is analyzed. Neutron calculations have been performed with the MCNPX code, and the principal design of the reactor part is developed. Neutron outflux at different outer parts of the reactor is calculated. Numerical simulations have been performed on the structure of a magnetic field in a model of the stellarator-mirror device, and that is achieved by switching off one or two coils of toroidal field in the Uragan-2M torsatron. The calculations predict the existence of closed magnetic surfaces under certain conditions. The confinement of fast particles in such a magnetic trap is analyzed.

The immune response of hemocytes of the insect Oncopeltus fasciatus against the flagellate Phytomonas serpens.

PubMed

Alves e Silva, Thiago L; Vasconcellos, Luiz R C; Lopes, Angela H; Souto-Padrón, Thaïs

2013-01-01

The genus Phytomonas includes parasites that are etiological agents of important plant diseases, especially in Central and South America. These parasites are transmitted to plants via the bite of an infected phytophagous hemipteran. Despite the economic impact of these parasites, many basic questions regarding the genus Phytomonas remain unanswered, such as the mechanism by which the parasites cope with the immune response of the insect vector. In this report, using a model of systemic infection, we describe the function of Oncopeltus fasciatus hemocytes in the immune response towards the tomato parasite Phytomonas serpens. Hemocytes respond to infection by trapping parasites in nodular structures and phagocytizing the parasites. In electron microscopy of hemocytes, parasites were located inside vacuoles, which appear fused with lysosomes. The parasites reached the O. fasciatus salivary glands at least six hours post-infection. After 72 hours post-infection, many parasites were attached to the salivary gland outer surface. Thus, the cellular responses did not kill all the parasites.

The Immune Response of Hemocytes of the Insect Oncopeltus fasciatus against the Flagellate Phytomonas serpens

PubMed Central

Alves e Silva, Thiago L.; Vasconcellos, Luiz R. C.

2013-01-01

The genus Phytomonas includes parasites that are etiological agents of important plant diseases, especially in Central and South America. These parasites are transmitted to plants via the bite of an infected phytophagous hemipteran. Despite the economic impact of these parasites, many basic questions regarding the genus Phytomonas remain unanswered, such as the mechanism by which the parasites cope with the immune response of the insect vector. In this report, using a model of systemic infection, we describe the function of Oncopeltus fasciatus hemocytes in the immune response towards the tomato parasite Phytomonas serpens. Hemocytes respond to infection by trapping parasites in nodular structures and phagocytizing the parasites. In electron microscopy of hemocytes, parasites were located inside vacuoles, which appear fused with lysosomes. The parasites reached the O. fasciatus salivary glands at least six hours post-infection. After 72 hours post-infection, many parasites were attached to the salivary gland outer surface. Thus, the cellular responses did not kill all the parasites. PMID:24015207

Effect of Coulomb interaction on time of flight of cold antiprotons launched from an ion trap

NASA Technical Reports Server (NTRS)

Camp, J. B.; Witteborn, F. C.

1993-01-01

Time-of-flight spectra for Maxwell-Boltzman (MB) distributions of antiprotons initially held in an ion trap and detected after being launched through a 50-cm-long shielding drift tube have been calculated. The distributions used are of temperature 0.4-40 K, cubic length 0.003-3.0 cm, and number 10-100 particles. The mutual Coulomb repulsion of the particles causes a reduction in the number of late arrival particles expected from the MB velocity distribution. The Coulomb energy is not equally divided among the particles during the expansion. The energy is transferred preferentially to the outer particles so that the reduction in the number of slow particles is not necessarily large. The reduction factor is found to be greater than unity when the potential energy of the trapped ions is greater than about 5 percent of the ions' kinetic energy and is about 2 for the launch parameters of the Los Alamos antiproton gravity experiment.

Analysis of inner and outer zone: OGO-1 and OGO-2 electron spectrometer and ion chamber data

NASA Technical Reports Server (NTRS)

Pfitzer, K. A.

1972-01-01

The dynamic processes governing the acceleration and loss of electrons in the radiation zones are investigated. The radial diffusion coefficient was determined for a McIlwain parameter between 1.6 and 2.2 for electrons having a first adiabatic invariant of 12 MeV/gauss. The coefficient is larger than earlier values and suggests that there exists a lower limit to the fluxes in the inner zone. The agreement between observed and calculated magnetic fields and particle fluxes is improved by using solar wind pressure as input to the magnetic field models. Changes in the plasma pressure can cause apparent local time asymmetries in particle flux. A comparison of the magnetic field models with observed location of the trapping boundary also indicates the need for including distributed currents within the magnetosphere. The high latitude trapping boundary is only weakly dependent on A sub p, and the trapping boundary data are improved by including in the models a stand-off distance which varies with the plasma pressure.

Trapped Modes in a Three-Layer Fluid

NASA Astrophysics Data System (ADS)

Saha, Sunanda; Bora, Swaroop Nandan

2018-03-01

In this work, trapped mode frequencies are computed for a submerged horizontal circular cylinder with the hydrodynamic set-up involving an infinite depth three-layer incompressible fluid with layer-wise different densities. The impermeable cylinder is fully immersed in either the bottom layer or the upper layer. The effect of surface tension at the surface of separation is neglected. In this set-up, there exist three wave numbers: the lowest one on the free surface and the other two on the internal interfaces. For each wave number, there exist two modes for which trapped waves exist. The existence of these trapped modes is shown by numerical evidence. We investigate the variation of these trapped modes subject to change in the depth of the middle layer as well as the submergence depth. We show numerically that two-layer and single-layer results cannot be recovered in the double and single limiting cases of the density ratios tending to unity. The existence of trapped modes shows that in general, a radiation condition for the waves at infinity is insufficient for the uniqueness of the solution of the scattering problem.

Dependence of trapped-flux-induced surface resistance of a large-grain Nb superconducting radio-frequency cavity on spatial temperature gradient during cooldown through T c

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Shichun; Kubo, Takayuki; Geng, R. L.

Recent studies by Romanenko et al. revealed that cooling down a superconducting cavity under a large spatial temperature gradient decreases the amount of trapped flux and leads to reduction of the residual surface resistance. In the present paper, the flux expulsion ratio and the trapped-flux-induced surface resistance of a large-grain cavity cooled down under a spatial temperature gradient up to 80K/m are studied under various applied magnetic fields from 5E-6 T to 2E-5 T. We show the flux expulsion ratio improves as the spatial temperature gradient increases, independent of the applied magnetic field: our results supports and enforces the previousmore » studies. We then analyze all RF measurement results obtained under different applied magnetic fields together by plotting the trapped- flux-induced surface resistance normalized by the applied magnetic field as a function of the spatial temperature gradient. All the data can be fitted by a single curve, which defines an empirical formula for the trapped- flux-induced surface resistance as a function of the spatial temperature gradient and applied magnetic field. The formula can fit not only the present results but also those obtained by Romanenko et al. previously. Furthermore, the sensitivity r fl of surface resistance from trapped magnetic flux of fine-grain and large-grain niobium cavities and the origin of dT/ds dependence of R fl/B a are also discussed.« less

Dependence of trapped-flux-induced surface resistance of a large-grain Nb superconducting radio-frequency cavity on spatial temperature gradient during cooldown through T c

DOE PAGES

Huang, Shichun; Kubo, Takayuki; Geng, R. L.

2016-08-26

Recent studies by Romanenko et al. revealed that cooling down a superconducting cavity under a large spatial temperature gradient decreases the amount of trapped flux and leads to reduction of the residual surface resistance. In the present paper, the flux expulsion ratio and the trapped-flux-induced surface resistance of a large-grain cavity cooled down under a spatial temperature gradient up to 80K/m are studied under various applied magnetic fields from 5E-6 T to 2E-5 T. We show the flux expulsion ratio improves as the spatial temperature gradient increases, independent of the applied magnetic field: our results supports and enforces the previousmore » studies. We then analyze all RF measurement results obtained under different applied magnetic fields together by plotting the trapped- flux-induced surface resistance normalized by the applied magnetic field as a function of the spatial temperature gradient. All the data can be fitted by a single curve, which defines an empirical formula for the trapped- flux-induced surface resistance as a function of the spatial temperature gradient and applied magnetic field. The formula can fit not only the present results but also those obtained by Romanenko et al. previously. Furthermore, the sensitivity r fl of surface resistance from trapped magnetic flux of fine-grain and large-grain niobium cavities and the origin of dT/ds dependence of R fl/B a are also discussed.« less

Two Step Acceleration Process of Electrons in the Outer Van Allen Radiation Belt by Time Domain Electric Field Bursts and Large Amplitude Chorus Waves

NASA Astrophysics Data System (ADS)

Agapitov, O. V.; Mozer, F.; Artemyev, A.; Krasnoselskikh, V.; Lejosne, S.

2014-12-01

A huge number of different non-linear structures (double layers, electron holes, non-linear whistlers, etc) have been observed by the electric field experiment on the Van Allen Probes in conjunction with relativistic electron acceleration in the Earth's outer radiation belt. These structures, found as short duration (~0.1 msec) quasi-periodic bursts of electric field in the high time resolution electric field waveform, have been called Time Domain Structures (TDS). They can quite effectively interact with radiation belt electrons. Due to the trapping of electrons into these non-linear structures, they are accelerated up to ~10 keV and their pitch angles are changed, especially for low energies (˜1 keV). Large amplitude electric field perturbations cause non-linear resonant trapping of electrons into the effective potential of the TDS and these electrons are then accelerated in the non-homogeneous magnetic field. These locally accelerated electrons create the "seed population" of several keV electrons that can be accelerated by coherent, large amplitude, upper band whistler waves to MeV energies in this two step acceleration process. All the elements of this chain acceleration mechanism have been observed by the Van Allen Probes.

Method and System for Weakening Shock Wave Strength at Leading Edge Surfaces of Vehicle in Supersonic Atmospheric Flight

NASA Technical Reports Server (NTRS)

Pritchett, Victor E., II (Inventor); Wang, Ten-See (Inventor); Blankson, Isaiah M. (Inventor); Daso, Endwell O. (Inventor); Farr, Rebecca Ann (Inventor); Auslender, Aaron Howard (Inventor); Plotkin, Kenneth J. (Inventor)

2015-01-01

A method and system are provided to weaken shock wave strength at leading edge surfaces of a vehicle in atmospheric flight. One or more flight-related attribute sensed along a vehicle's outer mold line are used to control the injection of a non-heated, non-plasma-producing gas into a local external flowfield of the vehicle from at least one leading-edge surface location along the vehicle's outer mold line. Pressure and/or mass flow rate of the gas so-injected is adjusted in order to cause a Rankine-Hugoniot Jump Condition along the vehicle's outer mold line to be violated.

Trapping in irradiated p +-n-n - silicon sensors at fluences anticipated at the HL-LHC outer tracker

DOE PAGES

Adam, W.

2016-04-22

The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200μm thick n-type silicon sensors are irradiated with protons of different energies to fluences of up to 3 x 10 15 neq/cm 2. Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determine the charge collection efficiencies separately for electrons and holes drifting through the sensor. The effective trapping rates are extracted by comparing the results to simulation. The electric field is simulated using Synopsys device simulationmore » assuming two effective defects. The generation and drift of charge carriers are simulated in an independent simulation based on PixelAV. The effective trapping rates are determined from the measured charge collection efficiencies and the simulated and measured time-resolved current pulses are compared. Furthermore, the effective trapping rates determined for both electrons and holes are about 50% smaller than those obtained using standard extrapolations of studies at low fluences and suggests an improved tracker performance over initial expectations.« less

2D Thermoluminescence imaging of dielectric surface long term charge memory of plasma surface interaction in DBD discharges

NASA Astrophysics Data System (ADS)

Ambrico, Paolo F.; Ambrico, Marianna; Schiavulli, Luigi; De Benedictis, Santolo

2014-07-01

The charge trapping effect due to the exposure of alumina surfaces to plasma has been studied in a volume dielectric barrier discharge (DBD) in Ar and He noble gases. The long lasting charge trapping of alumina dielectric plates, used as barriers in DBDs, is evidenced by an ex situ thermoluminescence (TL) experiment performed with a standard and a custom two-dimensional (2D)-TL apparatus. The spatial density of trapped surface charges is found to be strongly correlated to the plasma morphology, and the surface spatial memory lasted for several minutes to hours after plasma exposure. In the case of Ar, the plasma channel impact signature on the surface shows a higher equivalent radiation dose with respect to the surface plasma wave and the post-discharge species signature. As a consequence, for the development of discharges, inside the dielectric surface the availability of lower energy trapped electrons is larger in the first region of plasma impact. The reported spatial memory increases the likelihood of the occurrence of plasma filaments in the same position in different runs. In He plasmas, the dielectric barrier shows an almost uniform distribution of trapped charges, meaning that there is no preferred region for the development of the discharge. In all cases a slight asymmetry was shown in the direction of the gas flow. This can be interpreted as being due to the long-living species moving in the direction of the gas flow, corresponding with the TL side experiment on the sample exposed to the plasma afterglow. The maximum values and the integral of the 2D-TL images showed a linear relation with the total charge per ac cycle, corresponding with findings for the TL glow curve. In conclusion, 2D-TL images allow the retrieval of information regarding the plasma surface interaction such as the plasma morphology, trap sites and their activation temperature.

Backscattering from frost on icy satellites in the outer solar system

NASA Technical Reports Server (NTRS)

Verbiscer, Anne; Helfenstein, Paul; Veverka, Joseph

1990-01-01

Two extreme models are presented of how frost and ice might be intermixed on a typical satellite surface: areal and intimate mixing. Applying such models to selected representative satellite data, it is found that the frost component of the surfaces of these outer satellites must itself be backscattering, unlike its terrestrial counterpart. The difference may arise because frost particles can have much more complex internal textures under the low-temperature and low-gravity conditions of the outer satellites than is the case on earth.

Surface states and annihilation characteristics of positrons trapped at the oxidized Cu(100) surface

NASA Astrophysics Data System (ADS)

Fazleev, N. G.; Weiss, A. H.

2013-06-01

In this work we present the results of theoretical studies of positron surface and bulk states and annihilation probabilities of surface-trapped positrons with relevant core electrons at the oxidized Cu(100) surface under conditions of high oxygen coverage. Oxidation of the Cu(100) surface has been studied by performing an ab-initio investigation of the stability and electronic structure of the Cu(100) missing row reconstructed surface at various on-surface and subsurface oxygen coverages ranging from 0.5 to 1.5 monolayers using density functional theory (DFT). All studied structures have been found to be energetically more favorable as compared to structures formed by purely on-surface oxygen adsorption. The observed decrease in the positron work function when oxygen atoms occupy on-surface and subsurface sites has been attributed to a significant charge redistribution within the first two layers, buckling effects within each layer and an interlayer expansion. The computed positron binding energy, positron surface state wave function, and annihilation probabilities of the surface trapped positrons with relevant core electrons demonstrate their sensitivity to oxygen coverage, atomic structure of the topmost layers of surfaces, and charge transfer effects. Theoretical results are compared with experimental data obtained from studies of oxidation of the Cu(100) surface using positron annihilation induced Auger electron spectroscopy (PAES). The results presented provide an explanation for the changes observed in the probability of annihilation of surface trapped positrons with Cu 3p core-level electrons as a function of annealing temperature.

Dual-stage trapped-flux magnet cryostat for measurements at high magnetic fields

DOEpatents

Islam, Zahirul; Das, Ritesh K.; Weinstein, Roy

2015-04-14

A method and a dual-stage trapped-flux magnet cryostat apparatus are provided for implementing enhanced measurements at high magnetic fields. The dual-stage trapped-flux magnet cryostat system includes a trapped-flux magnet (TFM). A sample, for example, a single crystal, is adjustably positioned proximate to the surface of the TFM, using a translation stage such that the distance between the sample and the surface is selectively adjusted. A cryostat is provided with a first separate thermal stage provided for cooling the TFM and with a second separate thermal stage provided for cooling sample.

Turbine airfoil with a compliant outer wall

DOEpatents

Campbell, Christian X [Oviedo, FL; Morrison, Jay A [Oviedo, FL

2012-04-03

A turbine airfoil usable in a turbine engine with a cooling system and a compliant dual wall configuration configured to enable thermal expansion between inner and outer layers while eliminating stress formation in the outer layer is disclosed. The compliant dual wall configuration may be formed a dual wall formed from inner and outer layers separated by a support structure. The outer layer may be a compliant layer configured such that the outer layer may thermally expand and thereby reduce the stress within the outer layer. The outer layer may be formed from a nonplanar surface configured to thermally expand. In another embodiment, the outer layer may be planar and include a plurality of slots enabling unrestricted thermal expansion in a direction aligned with the outer layer.

Diaphragm flange and method for lowering particle beam impedance at connected beam tubes of a particle accelerator

DOEpatents

Biallas, George Herman

2017-07-04

A diaphragm flange for connecting the tubes in a particle accelerator while minimizing beamline impedance. The diaphragm flange includes an outer flange and a thin diaphragm integral with the outer flange. Bolt holes in the outer flange provide a means for bolting the diaphragm flange to an adjacent flange or beam tube having a mating bolt-hole pattern. The diaphragm flange includes a first surface for connection to the tube of a particle accelerator beamline and a second surface for connection to a CF flange. The second surface includes a recessed surface therein and a knife-edge on the recessed surface. The diaphragm includes a thickness that enables flexing of the integral diaphragm during assembly of beamline components. The knife-edge enables compression of a soft metal gasket to provide a leak-tight seal.

Evolution of relativistic outer belt electrons during extended quiescent period

NASA Astrophysics Data System (ADS)

Jaynes, A. N.; Li, X.; Schiller, Q.; Blum, L. W.; Tu, W.; Malaspina, D.; Turner, D.; Baker, D. N.; Kanekal, S. G.; Blake, J. B.; Wygant, J. R.

2013-12-01

To effectively study loss due to precipitation of relativistic electron fluxes in the radiation belt, it is necessary to isolate this loss from the Dst effect and magnetopause shadowing by studying loss during a time of relatively quiet geomagnetic activity. We present a study of the slow decay of 200 keV - 2 MeV electron populations in the outer radiation belt during an extended quiescent period from ~15 Dec 2012 - 10 Jan 2013, wherein Dst never extended below -25 nT. We incorporate particle measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) onboard the Colorado Student Space Weather Experiment (CSSWE) CubeSat with measurements from the Relativistic Electron Proton Telescope (REPT) and the Magnetic Electron Ion Spectrometer (MagEIS) on the Van Allen Probes twin spacecraft to understand the evolution of the electron populations across pitch angle and energy. First, we present REPTile measurements of the precipitating populations (along with trapped & quasi-trapped) at a low-earth orbit, offering a view into the loss cone that is not as easily resolved using only the Van Allen Probes. Electron loss to the atmosphere during this event is quantified through use of a precipitation loss model, using the REPTile measurements. Additionally, phase space densities are derived using pitch-angle-resolved flux data from the REPT and MagEIS instruments, as well as from THEMIS SST data. Finally, we present the net loss effect on the outer radiation belt content during this time, by incorporating the modeled precipitation loss (from REPTile measurements) with Van Allen Probes electron flux data. Hiss and chorus wave data, along with approximate plasmapause location, from Van Allen Probes' Electric Field and Waves Suite (EFW) completes the picture by suggesting mechanisms for the precipitation loss of relativistic electrons during quiet time.

The impact of nano-coating on surface charge accumulation of epoxy resin insulator: characteristic and mechanism

NASA Astrophysics Data System (ADS)

Qi, Bo; Gao, Chunjia; Lv, Yuzhen; Li, Chengrong; Tu, Youping; Xiong, Jun

2018-06-01

The flashover phenomenon of the insulator is the main cause for insulating failure of GIS/GIL, and one of the most critical impacting factors is the accumulation of surface charge. The common methods to restrain the surface charge accumulation are reviewed in this paper. Through the reasonable comparison and analysis of these methods, nano-coatings for the insulator were selected as a way to restrain the surface charge accumulation. Based on this, six nano-coated epoxy resin samples with different concentrations of P25-TiO2 nanoparticles were produced. A high precision 3D surface charge measurement system was developed in this paper with a spatial resolution of 4.0 mm2 and a charge resolution of 0.01 µC (m2 · mV)‑1. The experimental results for the epoxy resin sample showed that with the concentration of nanoparticles of the coating material increasing, the surface charge density tended to first decrease and then increase. In the sample coated with 0.5% concentration of nanoparticles, the suppression effect is the optimum, leading to a 63.8% reduction of charge density under DC voltage. The application test for actual nano-coated GIS/GIL basin insulator indicated that the maximum suppression degree for the charge density under DC voltage could reach 48.3%, while it could reach 22.2% for switching impulse voltage and 12.5% for AC context. The control mechanism of nano-coatings on charge accumulation was proposed based on the analysis for surface morphology features and traps characteristics; the shallow traps dominate in the migration of charges while the deep traps operate on the charge accumulation. With the concentration of nanoparticles in nano-coating material mounting up, the density of shallow traps continuously increases, while for deep traps, it first decreases and then increases. For the sample with 0.5% concentration of nanoparticles coated, the competition between shallow traps and deep traps comes to the most balanced state, producing the most significant suppression impact on surface charge accumulation.

Optical Forces on Non-Spherical Nanoparticles Trapped by Optical Waveguides

NASA Astrophysics Data System (ADS)

Hasan Ahmed, Dewan; Sung, Hyung Jin

2011-07-01

Numerical simulations of a solid-core polymer waveguide structure were performed to calculate the trapping efficiencies of particles with nanoscale dimensions smaller than the wavelength of the trapping beam. A three-dimensional (3-D) finite element method was employed to calculate the electromagnetic field. The inlet and outlet boundary conditions were obtained using an eigenvalue solver to determine the guided and evanescent mode profiles. The Maxwell stress tensor was considered for the calculation of the transverse and downward trapping efficiencies. A particle at the center of the waveguide showed minimal transverse trapping efficiency and maximal downward trapping efficiency. This trend gradually reversed as the particle moved away from the center of the waveguide. Particles with larger surface areas exhibited higher trapping efficiencies and tended to be trapped near the waveguide. Particles displaced from the wave input tended to be trapped at the waveguide surface. Simulation of an ellipsoidal particle showed that the orientation of the major axis along the waveguide's lateral z-coordinate significantly influenced the trapping efficiency. The particle dimensions along the z-coordinate were more critical than the gap distance (vertical displacement from the floor of the waveguide) between the ellipsoid particle and the waveguide. The present model was validated using the available results reported in the literature for different trapping efficiencies.

Induced-charge electroosmotic trapping of particles.

PubMed

Ren, Yukun; Liu, Weiyu; Jia, Yankai; Tao, Ye; Shao, Jinyou; Ding, Yucheng; Jiang, Hongyuan

2015-05-21

Position-controllable trapping of particles on the surface of a bipolar metal strip by induced-charge electroosmotic (ICEO) flow is presented herein. We demonstrate a nonlinear ICEO slip profile on the electrode surface accounting for stable particle trapping behaviors above the double-layer relaxation frequency, while no trapping occurs in the DC limit as a result of a strong upward fluidic drag induced by a linear ICEO slip profile. By extending an AC-flow field effect transistor from the DC limit to the AC field, we reveal that fixed-potential ICEO exceeding RC charging frequency can adjust the particle trapping position flexibly by generating controllable symmetry breaking in a vortex flow pattern. Our results open up new opportunities to manipulate microscopic objects in modern microfluidic systems by using ICEO.

Cold Bose-Einstein condensates for surface reflection

NASA Astrophysics Data System (ADS)

Saba, M.; Leanhardt, A. E.; Pasquini, T. A.; Sanner, C.; Schirotzek, A.; Shin, Y.; Pritchard, D. E.; Ketterle, W.

2004-05-01

Atoms can be reflected from a solid surface in spite of the attraction provided by the Casimir-Polder potential if their de Broglie wavelength exceeds the range of the attractive potential, an effect known as quantum reflection and demonstrated for atomic beams hitting a surface at grazing angle [1]. Quantum reflection of atomic Bose-Einstein condensates would have important consequences for experiments and applications requiring manipulation of condensates close to surfaces. However, no matter how cold a condensate is when approaching a surface, the atoms will hit the surface with a kinetic energy appropriate to the healing length, an energy roughly equal to the chemical potential and determined by atom-atom interactions. We circumvented this limitation by building a loose trap for the condensate, so that the atomic cloud can be kept very dilute, reaching the large healing length required to observe quantum reflection [2]. The trap consisted of a small single coil with electric current running in it that pushes the atoms upward, balancing gravity downward. The gravito-magnetic trap had a mean trap frequency of 1 Hz, so that condensates could sit in the trap for several minutes and reach temperatures as low as 500 pK, the lowest temperature ever recorded. We will then discuss how these condensates, whose healing length equals the condensate size, behave when approached to a silicon surface. [1] F. Shimizu, Phys. Rev. Lett. 86, 987 (2001); [2] A. E. Leanhardt et al., Science 301, 1513 (2003)

Methylation and in vivo expression of the surface-exposed Leptospira interrogans outer-membrane protein OmpL32.

PubMed

Eshghi, Azad; Pinne, Marija; Haake, David A; Zuerner, Richard L; Frank, Ami; Cameron, Caroline E

2012-03-01

Recent studies have revealed that bacterial protein methylation is a widespread post-translational modification that is required for virulence in selected pathogenic bacteria. In particular, altered methylation of outer-membrane proteins has been shown to modulate the effectiveness of the host immune response. In this study, 2D gel electrophoresis combined with MALDI-TOF MS identified a Leptospira interrogans serovar Copenhageni strain Fiocruz L1-130 protein, corresponding to ORF LIC11848, which undergoes extensive and differential methylation of glutamic acid residues. Immunofluorescence microscopy implicated LIC11848 as a surface-exposed outer-membrane protein, prompting the designation OmpL32. Indirect immunofluorescence microscopy of golden Syrian hamster liver and kidney sections revealed expression of OmpL32 during colonization of these organs. Identification of methylated surface-exposed outer-membrane proteins, such as OmpL32, provides a foundation for delineating the role of this post-translational modification in leptospiral virulence.

Impacts of raindrop evaporative cooling on tropical cyclone secondary eyewall formation

NASA Astrophysics Data System (ADS)

Ge, Xuyang; Guan, Liang; Yan, Ziyu

2018-06-01

The impacts of raindrop evaporative cooling on secondary eyewall formation (SEF) of simulated tropical cyclones are investigated using idealized numerical experiments. The results suggest that the raindrop evaporative cooling effect is beneficial to the development of secondary eyewall through the planetary boundary layer (PBL) cold pool process. The evaporative cooling-driven downdrafts bring about the surface cold pool beneath a precipitation cloud. This cold pool dynamics act as a lifting mechanism to trigger the outer convection. The radially outward propagation of spiral rainbands broadens the TC size, by which modifies the surface heat fluxes and thus outer convection. Furthermore, the unbalanced PBL process contributes to the SEF. The radially outward surface outflows forces convection at outer region and thus favors a larger TC size. A larger TC implies an enhanced inertial stability at the outer region, which favors a higher conversion efficiency of diabatic heating to kinetic energy.

Premixed direct injection nozzle for highly reactive fuels

DOEpatents

Ziminsky, Willy Steve; Johnson, Thomas Edward; Lacy, Benjamin Paul; York, William David; Uhm, Jong Ho; Zuo, Baifang

2013-09-24

A fuel/air mixing tube for use in a fuel/air mixing tube bundle is provided. The fuel/air mixing tube includes an outer tube wall extending axially along a tube axis between an inlet end and an exit end, the outer tube wall having a thickness extending between an inner tube surface having a inner diameter and an outer tube surface having an outer tube diameter. The tube further includes at least one fuel injection hole having a fuel injection hole diameter extending through the outer tube wall, the fuel injection hole having an injection angle relative to the tube axis. The invention provides good fuel air mixing with low combustion generated NOx and low flow pressure loss translating to a high gas turbine efficiency, that is durable, and resistant to flame holding and flash back.

Spin-glass-like freezing of inner and outer surface layers in hollow γ-Fe 2O 3 nanoparticles

DOE PAGES

Khurshid, Hafsa; Lampen-Kelley, Paula; Iglesias, Òscar; ...

2015-10-27

Disorder among surface spins largely dominates the magnetic response of ultrafine magnetic particle systems. In this work, we examine time-dependent magnetization in high-quality, monodisperse hollow maghemite nanoparticles (NPs) with a 14.8±0.5 nm outer diameter and enhanced surface-to-volume ratio. The nanoparticle ensemble exhibits spin-glass-like signatures in dc magnetic aging and memory protocols and ac magnetic susceptibility. The dynamics of the system slow near 50 K, and becomes frozen on experimental time scales below 20 K. Remanence curves indicate the development of magnetic irreversibility concurrent with the freezing of the spin dynamics. A strong exchange-bias effect and its training behavior point tomore » highly frustrated surface spins that rearrange much more slowly than interior spins with bulk coordination. Monte Carlo simulations of a hollow particle reproducing the experimental morphology corroborate strongly disordered surface layers with complex energy landscapes that underlie both glass-like dynamics and magnetic irreversibility. Calculated hysteresis loops reveal that magnetic behavior is not identical at the inner and outer surfaces, with spins at the outer surface layer of the 15 nm hollow particles exhibiting a higher degree of frustration. Lastly, our combined experimental and simulated results shed light on the origin of spin-glass-like phenomena and the important role played by the surface spins in magnetic hollow nanostructures.« less

Spin-glass-like freezing of inner and outer surface layers in hollow γ-Fe2O3 nanoparticles

PubMed Central

Khurshid, Hafsa; Lampen-Kelley, Paula; Iglesias, Òscar; Alonso, Javier; Phan, Manh-Huong; Sun, Cheng-Jun; Saboungi, Marie-Louise; Srikanth, Hariharan

2015-01-01

Disorder among surface spins is a dominant factor in the magnetic response of magnetic nanoparticle systems. In this work, we examine time-dependent magnetization in high-quality, monodisperse hollow maghemite nanoparticles (NPs) with a 14.8 ± 0.5 nm outer diameter and enhanced surface-to-volume ratio. The nanoparticle ensemble exhibits spin-glass-like signatures in dc magnetic aging and memory protocols and ac magnetic susceptibility. The dynamics of the system slow near 50 K, and become frozen on experimental time scales below 20 K. Remanence curves indicate the development of magnetic irreversibility concurrent with the freezing of the spin dynamics. A strong exchange-bias effect and its training behavior point to highly frustrated surface spins that rearrange much more slowly than interior spins. Monte Carlo simulations of a hollow particle corroborate strongly disordered surface layers with complex energy landscapes that underlie both glass-like dynamics and magnetic irreversibility. Calculated hysteresis loops reveal that magnetic behavior is not identical at the inner and outer surfaces, with spins at the outer surface layer of the 15 nm hollow particles exhibiting a higher degree of frustration. Our combined experimental and simulated results shed light on the origin of spin-glass-like phenomena and the important role played by the surface spins in magnetic hollow nanostructures. PMID:26503506

Direct measurement of interaction forces between a single bacterium and a flat plate.

PubMed

Klein, Jonah D; Clapp, Aaron R; Dickinson, Richard B

2003-05-15

A technique for precisely measuring the equilibrium and viscous interaction forces between a single bacterium and a flat surface as functions of separation distance is described. A single-beam gradient optical trap was used to micromanipulate the bacterium against a flat surface while evanescent wave light scattering was used to measure separation distances. Calibrating the optical trap far from the surface allowed the trapped bacterium to be used as a force probe. Equilibrium force-distance profiles were determined by measuring the deflection of the cell from the center of the optical trap at various trap positions. Simultaneously, viscous forces were determined by measuring the relaxation time for the fluctuating bacterium. Absolute distances were determined using a best-fit approximation to the theoretical prediction for the hindered mobility of a diffusing sphere near a wall. Using this approach, forces in the range from 0.01 to 4 pN were measured at near-nanometer resolution between Staphylococcus aureus and glass that was bare or coated with adsorbed protein.

Ultra-thin, light-trapping silicon solar cells

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.

1989-01-01

Design concepts for ultra-thin (2 to 10 microns) high efficiency single-crystal silicon cells are discussed. Light trapping allows more light to be absorbed at a given thickness, or allows thinner cells of a given Jsc. Extremely thin cells require low surface recombination velocity at both surfaces, including the ohmic contacts. Reduction of surface recombination by growth of heterojunctions of ZnS and GaP on Si has been demonstrated. The effects of these improvements on AM0 efficiency is shown. The peak efficiency increases, and the optimum thickness decreases. Cells under 10 microns thickness can retain almost optimum power. The increase of absorptance due to light trapping is considered. This is not a problem if the light-trapping cells are sufficiently thin. Ultra-thin cells have high radiation tolerance. A 2 microns thick light-trapping cell remains over 18 percent efficient after the equivalent of 20 years in geosynchronous orbit. Including a 50 microns thick coverglass, the thin cells had specific power after irradiation over ten times higher than the baseline design.

Development and Analysis of Cold Trap for Use in Fission Surface Power-Primary Test Circuit

NASA Technical Reports Server (NTRS)

Wolfe, T. M.; Dervan, C. A.; Pearson, J. B.; Godfroy, T. J.

2012-01-01

The design and analysis of a cold trap proposed for use in the purification of circulated eutectic sodium potassium (NaK-78) loops is presented. The cold trap is designed to be incorporated into the Fission Surface Power-Primary Test Circuit (FSP-PTC), which incorporates a pumped NaK loop to simulate in-space nuclear reactor-based technology using non-nuclear test methodology as developed by the Early Flight Fission-Test Facility. The FSP-PTC provides a test circuit for the development of fission surface power technology. This system operates at temperatures that would be similar to those found in a reactor (500-800 K). By dropping the operating temperature of a specified percentage of NaK flow through a bypass containing a forced circulation cold trap, the NaK purity level can be increased by precipitating oxides from the NaK and capturing them within the cold trap. This would prevent recirculation of these oxides back through the system, which may help prevent corrosion.

Preparing isolated vibrational wave packets with light-induced molecular potentials by chirped laser pulses

NASA Astrophysics Data System (ADS)

Vatasescu, Mihaela

2012-05-01

We consider a specific wave packet preparation arising from the control of tunneling in the 0g-(6s,6p3/2) double well potential of a Cs2 cold molecule with chirped laser pulses. Such a possibility to manipulate the population dynamics in the 0g-(6s,6p3/2) potential appears in a pump-dump scheme designed to form cold molecules by photoassociation of two cold cesium atoms. The initial population in the 0g-(6s,6p3/2) double well is a wave packet prepared in the outer well at large interatomic distances (94 a0) by a photoassociation step with a first chirped pulse, being a superposition of several vibrational states whose energies surround the energy of a tunneling resonance. Our present work is focused on a second delayed chirped pulse, coupling the 0g-(6s,6p3/2) surface with the a3Σu+(6s,6s) one in the zone of the double well barrier (15 a0) and creating deeply bound cold molecules in the a3Σu+(6s,6s) state. We explore the parameters choice (intensity, duration, chirp rate and sign) for this second pulse, showing that picoseconds pulses with a negative chirp can lead to trapping of population in the inner well in strongly bound vibrational states, out of the resonant tunneling able to transfer it back to the outer well.

Quantity, composition, and source of sediment collected in sediment traps along the fringing coral reef off Molokai, Hawaii

USGS Publications Warehouse

Bothner, Michael H.; Reynolds, R.L.; Casso, M.A.; Storlazzi, C.D.; Field, M.E.

2006-01-01

Sediment traps were used to evaluate the frequency, cause, and relative intensity of sediment mobility/resuspension along the fringing coral reef off southern Molokai (February 2000–May 2002). Two storms with high rainfall, floods, and exceptionally high waves resulted in sediment collection rates > 1000 times higher than during non-storm periods, primarily because of sediment resuspension by waves. Based on quantity and composition of trapped sediment, floods recharged the reef flat with land-derived sediment, but had a low potential for burying coral on the fore reef when accompanied by high waves.The trapped sediments have low concentrations of anthropogenic metals. The magnetic properties of trapped sediment may provide information about the sources of land-derived sediment reaching the fore reef. The high trapping rate and low sediment cover indicate that coral surfaces on the fore reef are exposed to transient resuspended sediment, and that the traps do not measure net sediment accumulation on the reef surface.

Quantity, composition, and source of sediment collected in sediment traps along the fringing coral reef off Molokai, Hawaii.

PubMed

Bothner, Michael H; Reynolds, Richard L; Casso, Michael A; Storlazzi, Curt D; Field, Michael E

2006-09-01

Sediment traps were used to evaluate the frequency, cause, and relative intensity of sediment mobility/resuspension along the fringing coral reef off southern Molokai (February 2000-May 2002). Two storms with high rainfall, floods, and exceptionally high waves resulted in sediment collection rates>1000 times higher than during non-storm periods, primarily because of sediment resuspension by waves. Based on quantity and composition of trapped sediment, floods recharged the reef flat with land-derived sediment, but had a low potential for burying coral on the fore reef when accompanied by high waves. The trapped sediments have low concentrations of anthropogenic metals. The magnetic properties of trapped sediment may provide information about the sources of land-derived sediment reaching the fore reef. The high trapping rate and low sediment cover indicate that coral surfaces on the fore reef are exposed to transient resuspended sediment, and that the traps do not measure net sediment accumulation on the reef surface.

Nocturnal Boundary Layer Measurements during the Amazonian Aerosol Characterization Experiment (amaze)

NASA Astrophysics Data System (ADS)

Tota, J.; Santos, R.; Fisch, G.; Querino, C.; Silva Dias, M.; Artaxo, P.; Guenther, A.; Martin, S.; Manzi, A.

2008-12-01

To characterize the Nocturnal Boundary Layer (NBL) hourly profiles of wind, pressure, temperature, humidity and 5 sizes particles concentration, were made by using tethered balloon at INPA tropical Amazon rainforest Reserve (Cuieiras) 100 km northwest from Manaus city. The measurements were made during the wet season March/2008. The NBL height was 100 to 150m, with a very well mixed layer close to surface associate with temperature inversion. The wind profiles shows a very clear low level in two nights, about 500 to 900 m, and, in general, all nights show an stable and cooler air layer close the surface uncoupled with outer residual boundary layer above. At the site a very clear drainage flow from north quadrant down slope eastward quadrant during very the stable cases. This findings is correlates with particles profiles where was commonly trapped by stable layer presenting high concentrations, for all 5 sizes measured, close to the surface at vegetation level and just above it. All nights presents high humidity with fog formation in three cases, associates with temperature below the 23°C. The wind speed were very low about 0.5 to calm, in generally associate with drainage flow down hill. The NBL dynamics is a discussion issue associate to the aerosol nocturnal mixing in complex terrain with tall vegetation, the currently AMAZE site case.

Nocturnal Boundary Layer Measurements during the Amazonian Aerosol Characterization Experiment (AMAZE)

NASA Astrophysics Data System (ADS)

Tota, J.; Fisch, G.; Santos, R.; Silva Dias, M.

2009-05-01

To characterize the Nocturnal Boundary Layer (NBL) hourly profiles of wind, pressure, temperature, humidity and 5 sizes particles concentration, were made by using tethered balloon at INPA tropical Amazon rainforest Reserve (Cuieiras) 100 km northwest from Manaus city. The measurements were made during the wet season March/2008. The NBL height was 100 to 150m, with a very well mixed layer close to surface associate with temperature inversion. The wind profiles shows a very clear low level in two nights, about 500 to 900 m, and, in general, all nights show an stable and cooler air layer close the surface uncoupled with outer residual boundary layer above. At the site a very clear drainage flow from north quadrant down slope eastward quadrant during very the stable cases. This findings is correlates with particles profiles where was commonly trapped by stable layer presenting high concentrations, for all 5 sizes measured, close to the surface at vegetation level and just above it. All nights presents high humidity with fog formation in three cases, associates with temperature below the 23C. The wind speed were very low about 0.5 to calm, in generally associate with drainage flow down hill. The NBL dynamics is a discussion issue associate to the aerosol nocturnal mixing in complex terrain with tall vegetation, the currently AMAZE site case.

Identification and characterization of Vibrio cholerae surface proteins by radioiodination.

PubMed Central

Richardson, K; Parker, C D

1985-01-01

Whole cells and isolated outer membrane from Vibrio cholerae (Classical, Inaba) were radiolabeled with Iodogen or Iodo-beads as catalyst. Radiolabeling of whole cells was shown to be surface specific by sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis of whole cells and cell fractions. Surface-labeled whole cells regularly showed 16 distinguishable protein species, of which nine were found in radiolabeled outer membrane preparations obtained by a lithium chloride-lithium acetate procedure. Eight of these proteins were found in outer membranes prepared by sucrose density gradient centrifugation and Triton X-100 extraction of radiolabeled whole cells. The mobility of several proteins was shown to be affected by temperature, and the major protein species exposed on the cell surface was shown to consist of at least two different peptides. Images PMID:3980099

The Path to High Q-Factors in Superconducting Accelerating Cavities: Flux Expulsion and Surface Resistance Optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinello, Martina

Accelerating cavities are devices resonating in the radio-frequency (RF) range used to accelerate charged particles in accelerators. Superconducting accelerating cavities are made out of niobium and operate at the liquid helium temperature. Even if superconducting, these resonating structures have some RF driven surface resistance that causes power dissipation. In order to decrease as much as possible the power losses, the cavity quality factor must be increased by decreasing the surface resistance. In this dissertation, the RF surface resistance is analyzed for a large variety of cavities made with different state-of-the-art surface treatments, with the goal of finding the surface treatmentmore » capable to return the highest Q-factor values in a cryomodule-like environment. This study analyzes not only the superconducting properties described by the BCS surface resistance, which is the contribution that takes into account dissipation due to quasi-particle excitations, but also the increasing of the surface resistance due to trapped flux. When cavities are cooled down below their critical temperature inside a cryomodule, there is always some remnant magnetic field that may be trapped increasing the global RF surface resistance. This thesis also analyzes how the fraction of external magnetic field, which is actually trapped in the cavity during the cooldown, can be minimized. This study is performed on an elliptical single-cell horizontally cooled cavity, resembling the geometry of cavities cooled in accelerator cryomodules. The horizontal cooldown study reveals that, as in case of the vertical cooldown, when the cooling is performed fast, large thermal gradients are created along the cavity helping magnetic flux expulsion. However, for this geometry the complete magnetic flux expulsion from the cavity equator is more difficult to achieve. This becomes even more challenging in presence of orthogonal magnetic field, that is easily trapped on top of the cavity equator causing temperature rising. The physics behind the magnetic flux expulsion is also analyzed, showing that during a fast cooldown the magnetic field structures, called vortices, tend to move in the same direction of the thermal gradient, from the Meissner state region to the mixed state region, minimizing the Gibbs free energy. On the other hand, during a slow cool down, not only the vortices movement is limited by the absence of thermal gradients, but, also, at the end of the superconducting transition, the magnetic field concentrates along randomly distributed normal-conducting region from which it cannot be expelled anymore. The systematic study of the surface resistance components performed for the different surface treatments, reveals that the BCS surface resistance and the trapped flux surface resistance have opposite trends as a function of the surface impurity content, defined by the mean free path. At medium field value, the BCS surface resistance is minimized for nitrogen-doped cavities and significantly larger for standard niobium cavities. On the other hand, Nitrogen-doped cavities show larger dissipation due to trapped flux. This is consequence of the bell-shaped trend of the trapped flux sensitivity as a function of the mean free path. Such experimental findings allow also a better understanding of the RF dissipation due to trapped flux. The best compromise between all the surface resistance components, taking into account the possibility of trapping some external magnetic field, is given by light nitrogen-doping treatments. However, the beneficial effects of the nitrogen-doping is completely lost when large amount of magnetic field is trapped during the cooldown, underlying the importance of both cooldown and magnetic field shielding optimization in high quality factors cryomodules.« less

Investigation into aerodynamic and heat transfer of annular channel with inner and outer surface of the shape truncated cone and swirling fluid flow

NASA Astrophysics Data System (ADS)

Leukhin, Yu L.; Pankratov, E. V.; Karpov, S. V.

2017-11-01

We have carried out Investigation into aerodynamic and convective heat transfer of the annular channel. Inner or outer surface of annular channel has shape of blunt-nosed cone tapering to outlet end. Truncated cone connects to a cyclone swirling flow generator. Asymmetric and unsteady flow from the swirling generator in the shape of periodic process gives rise to the formation of secondary flows of the type Taylor-Görtler vortices. These vortices occupy the whole space of the annular channel, with the axes, which coincide with the motion direction of the major stream. Contraction of cross-sectional area of channel (in both cases 52%) causes a marked increase in total velocity of flow, primarily due to its axial component and promotes a more intensive vortex generation. Vortex structures have a significant influence on both average heat transfer and surface distribution. At cross-sections of the annular channel we observe similarity of curves describing distribution of total velocity about wall and heat flux density on the surface. The coordinates of maximum and minimum values of velocity and heat flux coincide. At the average cross-section channel of maximum value of heat transfer is greater than minimum of about by a factor of 2.7 times for outer heat transfer surface and about by a factor of 1.7 times for inner heat transfer surface. Taper channel has a much higher influence on heat transfer of the inner surface than the outer surface and manifests itself at lower values of dimensionless axial coordinate. For the investigated taper cone geometry of the annular channel the heat transfer coefficient of inner surface increases at the outlet section and exceeds value in comparison with straight-line section by 91 … 98%. Heat transfer of the outer cylinder in the same section increases only by 5 … 11%. The increase in average heat transfer over the surfaces is 36% and 4% respectively.

How can horseflies be captured by solar panels? A new concept of tabanid traps using light polarization and electricity produced by photovoltaics.

PubMed

Blahó, Miklós; Egri, Ádám; Barta, András; Antoni, Györgyi; Kriska, György; Horváth, Gábor

2012-10-26

Horseflies (Diptera: Tabanidae) can cause severe problems for humans and livestock because of the continuous annoyance performed and the diseases vectored by the haematophagous females. Therefore, effective horsefly traps are in large demand, especially for stock-breeders. To catch horseflies, several kinds of traps have been developed, many of them attracting these insects visually with the aid of a black ball. The recently discovered positive polarotaxis (attraction to horizontally polarized light) in several horsefly species can be used to design traps that capture female and male horseflies. The aim of this work is to present the concept of such a trap based on two novel principles: (1) the visual target of the trap is a horizontal solar panel (photovoltaics) attracting polarotactic horseflies by means of the highly and horizontally polarized light reflected from the photovoltaic surface. (2) The horseflies trying to touch or land on the photovoltaic trap surface are perished by the mechanical hit of a wire rotated quickly with an electromotor supplied by the photovoltaics-produced electricity. Thus, the photovoltaics is bifunctional: its horizontally polarized reflected light signal attracts water-seeking, polarotactic horseflies, and it produces the electricity necessary to rotate the wire. We describe here the concept and design of this new horsefly trap, the effectiveness of which was demonstrated in field experiments. The advantages and disadvantages of the trap are discussed. Using imaging polarimetry, we measured the reflection-polarization characteristics of the photovoltaic trap surface demonstrating the optical reason for the polarotactic attractiveness to horseflies. Copyright © 2012 Elsevier B.V. All rights reserved.

δ13C and δ15N Values of Sediment-trap Particles in the Japan and Yamato Basins and Comparison with the Core-top Values in the East/Japan Sea

NASA Astrophysics Data System (ADS)

Khim, Boo-Keun; Otosaka, Shigeyoshi; Park, Kyung-Ae; Noriki, Shinichiro

2018-03-01

Investigation of sediment-trap deployments in the East/Japan Sea (EJS) showed that distinct seasonal variations in particulate organic carbon (POC) fluxes of intermediate-water sediment-traps clearly corresponded to changes in chlorophyll a concentrations estimated from SeaWiFS data. The prominent high POC flux periods (e.g., March) were strongly correlated with the enhanced surface-water phytoplankton blooms. Deep-water sedimenttraps exhibited similar variation patterns to intermediate-water sediment-traps. However, their total flux and POC flux were higher than those of intermediate-water sediment-traps during some months (e.g., April and May), indicating the lateral delivery of some particles to the deep-water sediment-traps. Distinct seasonal δ13C and δ15N variations in settling particles of the intermediate-water sediment-traps were observed, strongly supporting the notion of seasonal primary production. Seasonal variations in δ13C and δ15N values from the deep-water sediment-traps were similar to those of the intermediate-water sediment-traps. However, the difference in δ13C and δ15N values between the intermediate-water and the deepwater sediment-traps may be attributed to degradation of organic matter as it sank through the water column. Comparison of fluxweighted δ13C and δ15N mean values between the deep-water sediment-traps and the core-top sediments showed that strong selective loss of organic matter components (lipids) depleted in 13C and 15N occurred during sediment burial. Nonetheless, the results of our study indicate that particles in the deep-water sediment-trap deposited as surface sediments on the seafloor preserve the record of surface-water conditions, highlighting the usefulness of sedimentary δ13C and δ15N values as a paleoceanographic application in the EJS.

Broadband angle-independent antireflection coatings on nanostructured light trapping solar cells

NASA Astrophysics Data System (ADS)

Vázquez-Guardado, Abraham; Boroumand, Javaneh; Franklin, Daniel; Chanda, Debashis

2018-03-01

Backscattering from nanostructured surfaces greatly diminishes the efficacy of light trapping solar cells. While the analytical design of broadband, angle-independent antireflection coatings on nanostructured surfaces proved inefficient, numerical optimization proves a viable alternative. Here, we numerically design and experimentally verify the performance of single and bilayer antireflection coatings on a 2D hexagonal diffractive light trapping pattern on crystalline silicon substrates. Three well-known antireflection coatings, aluminum oxide, silicon nitride, and silicon oxide, which also double as high-quality surface passivation materials, are studied in the 400-1000 nm band. By varying thickness and conformity, the optimal parameters that minimize the broadband total reflectance (specular and scattering) from the nanostructured surface are obtained. The design results in a single-layer antireflection coating with normal-angle wavelength-integrated reflectance below 4% and a bilayer antireflection coating demonstrating reflection down to 1.5%. We show experimentally an angle-averaged reflectance of ˜5.2 % up to 60° incident angle from the optimized bilayer antireflection-coated nanostructured surface, paving the path toward practical implementation of the light trapping solar cells.

Compact neutron imaging system using axisymmetric mirrors

DOEpatents

Khaykovich, Boris; Moncton, David E; Gubarev, Mikhail V; Ramsey, Brian D; Engelhaupt, Darell E

2014-05-27

A dispersed release of neutrons is generated from a source. A portion of this dispersed neutron release is reflected by surfaces of a plurality of nested, axisymmetric mirrors in at least an inner mirror layer and an outer mirror layer, wherein the neutrons reflected by the inner mirror layer are incident on at least one mirror surface of the inner mirror layer N times, wherein N is an integer, and wherein neutrons reflected by the outer mirror are incident on a plurality of mirror surfaces of the outer layer N+i times, where i is a positive integer, to redirect the neutrons toward a target. The mirrors can be formed by a periodically reversed pulsed-plating process.

Concentric wrench for blind access opening in a turbine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laurer, Kurt Neal; Drlik, Gary Joseph; Gibler, Edward Eugene

The concentric wrench includes an outer tube having flats at one end and a gripping surface at an opposite end. An inner tube has interior flats at one end and a gripping surface at its opposite end. With the inner and outer tubes disposed about a pressure transmitting conduit, the tubes may be inserted into a blind access opening in the outer turbine casing to engage the flats of the tubes against hex nuts of an internal fitting. By relatively rotating the tubes using the externally exposed gripping surfaces, the threaded connection between the parts of the fitting bearing themore » respective hex nuts can be tightened or loosened.« less

Orbital Winch

NASA Technical Reports Server (NTRS)

Hoyt, Robert (Inventor); Slostad, Jeffrey T. (Inventor); Frank, Scott (Inventor); Barnes, Ian M. (Inventor)

2016-01-01

Orbital winch having: lower and upper frames; spool having upper and lower flanges with lower flange attached to lower frame; axial tether guide mounted to upper frame; secondary slewing ring coaxial with spool and rotatably mounted to upper frame, wherein secondary slewing ring's outer surface has gearing; upper tether guide mounted to inner surface of secondary slewing ring; linear translation means having upper end mounted to upper frame and lower end mounted on lower frame; primary slewing ring rotatably mounted within linear translation means allowing translation axially between flanges, wherein primary slewing ring's outer surface has gearing; lower tether guide mounted on primary slewing ring's inner surface; pinion rod having upper end mounted to upper frame and lower end mounted to lower frame, wherein pinion rod's teeth engage primary and secondary slewing rings' outer surface teeth; and tether passing through axial, upper, and lower tether guides and winding around spool.

Systems and methods for determining strength of cylindrical structures by internal pressure loading

DOEpatents

DeTeresa, Steven John; Groves, Scott Eric; Sanchez, Roberto Joseph; Andrade, William Andrew

2015-08-04

In one embodiment, an apparatus, includes: a mandrel; an expansion cylinder, comprising: opposite first and second ends; an inner circumferential surface extending between the ends and characterized by an inner diameter, the inner circumferential surface defining a hollow cavity; an outer circumferential surface extending between the ends and characterized by an outer diameter that is greater than the inner diameter; and a plurality of slots extending from the inner circumferential surface to the outer circumferential surface and latitudinally oriented between the ends; and one or more base plates configured to engage one of the ends of the expansion cylinder. In another embodiment, a method includes: arranging an expansion cylinder inside a test cylinder; arranging a mandrel inside the expansion cylinder; applying a force to the mandrel for exerting a radial force on the expansion cylinder; and detecting one or more indicia of structural failure of the test cylinder.

Trapped-ion quantum logic gates based on oscillating magnetic fields.

PubMed

Ospelkaus, C; Langer, C E; Amini, J M; Brown, K R; Leibfried, D; Wineland, D J

2008-08-29

Oscillating magnetic fields and field gradients can be used to implement single-qubit rotations and entangling multiqubit quantum gates for trapped-ion quantum information processing (QIP). With fields generated by currents in microfabricated surface-electrode traps, it should be possible to achieve gate speeds that are comparable to those of optically induced gates for realistic distances between the ion crystal and the electrode surface. Magnetic-field-mediated gates have the potential to significantly reduce the overhead in laser-beam control and motional-state initialization compared to current QIP experiments with trapped ions and will eliminate spontaneous scattering, a fundamental source of decoherence in laser-mediated gates.

Surface Traps in Colloidal Quantum Dots: A Combined Experimental and Theoretical Perspective.

PubMed

Giansante, Carlo; Infante, Ivan

2017-10-19

Surface traps are ubiquitous to nanoscopic semiconductor materials. Understanding their atomistic origin and manipulating them chemically have capital importance to design defect-free colloidal quantum dots and make a leap forward in the development of efficient optoelectronic devices. Recent advances in computing power established computational chemistry as a powerful tool to describe accurately complex chemical species and nowadays it became conceivable to model colloidal quantum dots with realistic sizes and shapes. In this Perspective, we combine the knowledge gathered in recent experimental findings with the computation of quantum dot electronic structures. We analyze three different systems: namely, CdSe, PbS, and CsPbI 3 as benchmark semiconductor nanocrystals showing how different types of trap states can form at their surface. In addition, we suggest experimental healing of such traps according to their chemical origin and nanocrystal composition.

Quantitative ionization chamber alignment to a water surface: Theory and simulation.

PubMed

Siebers, Jeffrey V; Ververs, James D; Tessier, Frédéric

2017-07-01

To examine the response properties of cylindrical cavity ionization chambers (ICs) in the depth-ionization buildup region so as to obtain a robust chamber-signal - based method for definitive water surface identification, hence absolute ionization chamber depth localization. An analytical model with simplistic physics and geometry is developed to explore the theoretical aspects of ionization chamber response near a phantom water surface. Monte Carlo simulations with full physics and ionization chamber geometry are utilized to extend the model's findings to realistic ion chambers in realistic beams and to study the effects of IC design parameters on the entrance dose response. Design parameters studied include full and simplified IC designs with varying central electrode thickness, wall thickness, and outer chamber radius. Piecewise continuous fits to the depth-ionization signal gradient are used to quantify potential deviation of the gradient discontinuity from the chamber outer radius. Exponential, power, and hyperbolic sine functional forms are used to model the gradient for chamber depths of zero to the depth of the gradient discontinuity. The depth-ionization gradient as a function of depth is maximized and discontinuous when a submerged IC's outer radius coincides with the water surface. We term this depth the gradient chamber alignment point (gCAP). The maximum deviation between the gCAP location and the chamber outer radius is 0.13 mm for a hypothetical 4 mm thick wall, 6.45 mm outer radius chamber using the power function fit, however, the chamber outer radius is within the 95% confidence interval of the gCAP determined by this fit. gCAP dependence on the chamber wall thickness is possible, but not at a clinically relevant level. The depth-ionization gradient has a discontinuity and is maximized when the outer-radius of a submerged IC coincides with the water surface. This feature can be used to auto-align ICs to the water surface at the time of scanning and/or be applied retrospectively to scan data to quantify absolute IC depth. Utilization of the gCAP should yield accurate and reproducible depth calibration for clinical depth-ionization measurements between setups and between users. © 2017 American Association of Physicists in Medicine.

Lead determination at ng/mL level by flame atomic absorption spectrometry using a tantalum coated slotted quartz tube atom trap.

PubMed

Demirtaş, İlknur; Bakırdere, Sezgin; Ataman, O Yavuz

2015-06-01

Flame atomic absorption spectrometry (FAAS) still keeps its importance despite the relatively low sensitivity; because it is a simple and economical technique for determination of metals. In recent years, atom traps have been developed to increase the sensitivity of FAAS. Although the detection limit of FAAS is only at the level of µg/mL, with the use of atom traps it can reach to ng/mL. Slotted quartz tube (SQT) is one of the atom traps used to improve sensitivity. In atom trapping mode of SQT, analyte is trapped on-line in SQT for few minutes using ordinary sample aspiration, followed by the introduction of a small volume of organic solvent to effect the revolatilization and atomization of analyte species resulting in a transient signal. This system is economical, commercially available and easy to use. In this study, a sensitive analytical method was developed for the determination of lead with the help of SQT atom trapping flame atomization (SQT-AT-FAAS). 574 Fold sensitivity enhancement was obtained at a sample suction rate of 3.9 mL/min for 5.0 min trapping period with respect to FAAS. Organic solvent was selected as 40 µL of methyl isobutyl ketone (MIBK). To obtain a further sensitivity enhancement inner surface of SQT was coated with several transition metals. The best sensitivity enhancement, 1650 fold enhancement, was obtained by the Ta-coated SQT-AT-FAAS. In addition, chemical nature of Pb species trapped on quartz and Ta surface, and the chemical nature of Ta on quartz surface were investigated by X-ray photoelectron spectroscopy (XPS) and Raman Spectroscopy. Raman spectrometric results indicate that tantalum is coated on SQT surface in the form of Ta2O5. XPS studies revealed that the oxidation state of Pb in species trapped on both bare and Ta coated SQT surfaces is +2. For the accuracy check, the analyses of standard reference material were performed by use of SCP SCIENCE EnviroMAT Low (EU-L-2) and results for Pb were to be in good agreement with the certified value using SQT-AT-FAAS and Ta coated-SQT. Copyright © 2015 Elsevier B.V. All rights reserved.

Packer arrangements for oil wells and the like

DOEpatents

Harvey, Andrew C.; McFadden, David H.

1981-11-24

The packer includes an elongated tubular casing, and a metal ring is disposed in its entirety within an annular recess in the casing. The recess has a circumferential opening extending entirely around the peripheral outer surface of the casing. Hydraulic fluid is flowed into the recess to apply pressure to the inner peripheral surface of the metal ring to expand the ring radially outwardly and force its outer peripheral surface through the circumferential opening and into annular sealing engagement with the opposed surface of the well casing.

New configuration for efficient and durable copper coating on the outer surface of a tube

DOE PAGES

Ahmad, Irfan; Chapman, Steven F.; Velas, Katherine M.; ...

2017-03-27

A well-adhered copper coating on stainless steel power coupler parts is required in superconducting radio frequency (SRF) accelerators. Radio frequency power coupler parts are complex, tubelike stainless steel structures, which require copper coating on their outer and inner surfaces. Conventional copper electroplating sometimes produces films with inadequate adhesion strength for SRF applications. Electroplating also requires a thin nickel strike layer under the copper coating, whose magnetic properties can be detrimental to SRF applications. Coaxial energetic deposition (CED) and sputtering methods have demonstrated efficient conformal coating on the inner surfaces of tubes but coating the outer surface of a tube ismore » challenging because these coating methods are line of sight. When the substrate is off axis and the plasma source is on axis, only a small section of the substrate’s outer surface is exposed to the source cathode. The conventional approach is to rotate the tube to achieve uniformity across the outer surface. This method results in poor film thickness uniformity and wastes most of the source plasma. Alameda Applied Sciences Corporation (AASC) has developed a novel configuration called hollow external cathode CED (HEC-CED) to overcome these issues. HEC-CED produces a film with uniform thickness and efficiently uses all eroded source material. Furthermore, the Cu film deposited on the outside of a stainless steel tube using the new HEC-CED configuration survived a high pressure water rinse adhesion test. HEC-CED can be used to coat the outside of any cylindrical structure.« less

New configuration for efficient and durable copper coating on the outer surface of a tube

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, Irfan; Chapman, Steven F.; Velas, Katherine M.

A well-adhered copper coating on stainless steel power coupler parts is required in superconducting radio frequency (SRF) accelerators. Radio frequency power coupler parts are complex, tubelike stainless steel structures, which require copper coating on their outer and inner surfaces. Conventional copper electroplating sometimes produces films with inadequate adhesion strength for SRF applications. Electroplating also requires a thin nickel strike layer under the copper coating, whose magnetic properties can be detrimental to SRF applications. Coaxial energetic deposition (CED) and sputtering methods have demonstrated efficient conformal coating on the inner surfaces of tubes but coating the outer surface of a tube ismore » challenging because these coating methods are line of sight. When the substrate is off axis and the plasma source is on axis, only a small section of the substrate’s outer surface is exposed to the source cathode. The conventional approach is to rotate the tube to achieve uniformity across the outer surface. This method results in poor film thickness uniformity and wastes most of the source plasma. Alameda Applied Sciences Corporation (AASC) has developed a novel configuration called hollow external cathode CED (HEC-CED) to overcome these issues. HEC-CED produces a film with uniform thickness and efficiently uses all eroded source material. Furthermore, the Cu film deposited on the outside of a stainless steel tube using the new HEC-CED configuration survived a high pressure water rinse adhesion test. HEC-CED can be used to coat the outside of any cylindrical structure.« less

Quantum trajectories in elastic atom-surface scattering: threshold and selective adsorption resonances.

PubMed

Sanz, A S; Miret-Artés, S

2005-01-01

The elastic resonant scattering of He atoms off the Cu(117) surface is fully described with the formalism of quantum trajectories provided by Bohmian mechanics. Within this theory of quantum motion, the concept of trapping is widely studied and discussed. Classically, atoms undergo impulsive collisions with the surface, and then the trapped motion takes place covering at least two consecutive unit cells. However, from a Bohmian viewpoint, atom trajectories can smoothly adjust to the equipotential energy surface profile in a sort of sliding motion; thus the trapping process could eventually occur within one single unit cell. In particular, both threshold and selective adsorption resonances are explained by means of this quantum trapping considering different space and time scales. Furthermore, a mapping between each region of the (initial) incoming plane wave and the different parts of the diffraction and resonance patterns can be easily established, an important issue only provided by a quantum trajectory formalism. (c) 2005 American Institute of Physics.

Surface acceptor states in MBE-grown CdTe layers

NASA Astrophysics Data System (ADS)

Wichrowska, Karolina; Wosinski, Tadeusz; Tkaczyk, Zbigniew; Kolkovsky, Valery; Karczewski, Grzegorz

2018-04-01

A deep-level hole trap associated with surface defect states has been revealed with deep-level transient spectroscopy investigations of metal-semiconductor junctions fabricated on nitrogen doped p-type CdTe layers grown by the molecular-beam epitaxy technique. The trap displayed the hole-emission activation energy of 0.33 eV and the logarithmic capture kinetics indicating its relation to extended defect states at the metal-semiconductor interface. Strong electric-field-induced enhancement of the thermal emission rate of holes from the trap has been attributed to the phonon-assisted tunneling effect from defect states involving very large lattice relaxation around the defect and metastability of its occupied state. Passivation with ammonium sulfide of the CdTe surface, prior to metallization, results in a significant decrease in the trap density. It also results in a distinct reduction in the width of the surface-acceptor-state-induced hysteresis loops in the capacitance vs. voltage characteristics of the metal-semiconductor junctions.

Zone heated diesel particulate filter electrical connection

DOEpatents

Gonze, Eugene V.; Paratore, Jr., Michael J.

2010-03-30

An electrical connection system for a particulate filter is provided. The system includes: a particulate filter (PF) disposed within an outer shell wherein the PF is segmented into a plurality of heating zones; an outer mat disposed between the particulate filter and the outer shell; an electrical connector coupled to the outer shell of the PF; and a plurality of printed circuit connections that extend along the outer surface of the PF from the electrical connector to the plurality of heating zones.

Cloning and expression of soluble truncated variants of Borrelia OspA, OspB and Vmp7

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunn, J.J.; Barbour, A.G.

1996-11-05

A method is provided for preparing soluble recombinant variations of Borrelia lipoproteins such as Borrelia burgdorferi outer surface protein A (OspA) and outer surface protein B (OspB), and B. hermsii variable major protein 7 (Vmp7). The method includes synthesizing a set of oligonucleotide primers, amplifying the template DNA utilizing the PCR, purifying the amplification products, cloning the amplification products into a suitable expression vector, transforming a suitable host utilizing the cloned expression vector, cultivating the transformed host for protein production and subsequently isolating and purifying the resulting protein. Also provided are soluble, recombinant variations of Borrelia burgdorferi outer surface proteinmore » A (OspA), outer surface protein B (OspB), and B. hermsii variable major protein 7 (Vmp7). The expression vectors harboring DNA encoding the recombinant variations, pET9-OspA, pET9-OspB and pET9-Vmp7, as well as the E. coli host BL21(DE3)/pLysS transformed with each of these vectors, are also disclosed. 38 figs.« less

Identification of Major Outer Surface Proteins of Streptococcus agalactiae

PubMed Central

Hughes, Martin J. G.; Moore, Joanne C.; Lane, Jonathan D.; Wilson, Rebecca; Pribul, Philippa K.; Younes, Zabin N.; Dobson, Richard J.; Everest, Paul; Reason, Andrew J.; Redfern, Joanne M.; Greer, Fiona M.; Paxton, Thanai; Panico, Maria; Morris, Howard R.; Feldman, Robert G.; Santangelo, Joseph D.

2002-01-01

To identify the major outer surface proteins of Streptococcus agalactiae (group B streptococcus), a proteomic analysis was undertaken. An extract of the outer surface proteins was separated by two-dimensional electrophoresis. The visualized spots were identified through a combination of peptide sequencing and reverse genetic methodologies. Of the 30 major spots identified as S. agalactiae specific, 27 have been identified. Six of these proteins, previously unidentified in S. agalactiae, were sequenced and cloned. These were ornithine carbamoyltransferase, phosphoglycerate kinase, nonphosphorylating glyceraldehyde-3-phosphate dehydrogenase, purine nucleoside phosphorylase, enolase, and glucose-6-phosphate isomerase. Using a gram-positive expression system, we have overexpressed two of these proteins in an in vitro system. These recombinant, purified proteins were used to raise antisera. The identification of these proteins as residing on the outer surface was confirmed by the ability of the antisera to react against whole, live bacteria. Further, in a neonatal-animal model system, we demonstrate that some of these sera are protective against lethal doses of bacteria. These studies demonstrate the successful application of proteomics as a technique for identifying vaccine candidates. PMID:11854208

Cloning and expression of soluble truncated variants of Borrelia OspA, OspB and Vmp7

DOEpatents

Dunn, John J.; Barbour, Alan G.

1996-11-05

A method is provided herein for preparing soluble recombinant variations of Borrelia lipoproteins such as Borrelia burgdorferi outer surface protein A (OspA) and outer surface protein B (OspB), and B. hermsii variable major protein 7 (Vmp7). The method includes synthesizing a set of oligonucleotide primers, amplifying the template DNA utilizing the PCR, purifying the amplification products, cloning the amplification products into a suitable expression vector, transforming a suitable host utilizing the cloned expression vector, cultivating the transformed host for protein production and subsequently isolating and purifying the resulting protein. Also provided are soluble, recombinant variations of Borrelia burgdorferi outer surface protein A (OspA), outer surface protein B (OspB), and B. hermsii variable major protein 7 (Vmp7). The expression vectors harboring DNA encoding the recombinant variations, pET9-OspA, pET9-OspB and pET9-Vmp7, as well as the E. coli host BL21(DE3)/pLysS transformed with each of these vectors, are also disclosed.

Cloning and expression of soluble truncated variants of Borrelia OspA, OspB and Vmp7

DOEpatents

Dunn, J.J.; Barbour, A.G.

1996-11-05

A method is provided for preparing soluble recombinant variations of Borrelia lipoproteins such as Borrelia burgdorferi outer surface protein A (OspA) and outer surface protein B (OspB), and B. hermsii variable major protein 7 (Vmp7). The method includes synthesizing a set of oligonucleotide primers, amplifying the template DNA utilizing the PCR, purifying the amplification products, cloning the amplification products into a suitable expression vector, transforming a suitable host utilizing the cloned expression vector, cultivating the transformed host for protein production and subsequently isolating and purifying the resulting protein. Also provided are soluble, recombinant variations of Borrelia burgdorferi outer surface protein A (OspA), outer surface protein B (OspB), and B. hermsii variable major protein 7 (Vmp7). The expression vectors harboring DNA encoding the recombinant variations, pET9-OspA, pET9-OspB and pET9-Vmp7, as well as the E. coli host BL21(DE3)/pLysS transformed with each of these vectors, are also disclosed. 38 figs.

Hot gas path component having cast-in features for near wall cooling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miranda, Carlos Miguel; Kottilingam, Srikanth Chandrudu; Lacy, Benjamin Paul

A hot gas path component includes a substrate having an outer surface and an inner surface. The inner surface of the substrate defines at least one interior space. At least a portion of the outer surface of the substrate includes a recess formed therein. The recess includes a bottom surface and a groove extending at least partially along the bottom surface of the recess. A cover is disposed within the recess and covers at least a portion of the groove. The groove is configured to channel a cooling fluid therethrough to cool the cover.

Bioreplicated visual features of nanofabricated buprestid beetle decoys evoke stereotypical male mating flights

PubMed Central

Domingue, Michael J.; Lakhtakia, Akhlesh; Pulsifer, Drew P.; Hall, Loyal P.; Badding, John V.; Bischof, Jesse L.; Martín-Palma, Raúl J.; Imrei, Zoltán; Janik, Gergely; Mastro, Victor C.; Hazen, Missy; Baker, Thomas C.

2014-01-01

Recent advances in nanoscale bioreplication processes present the potential for novel basic and applied research into organismal behavioral processes. Insect behavior potentially could be affected by physical features existing at the nanoscale level. We used nano-bioreplicated visual decoys of female emerald ash borer beetles (Agrilus planipennis) to evoke stereotypical mate-finding behavior, whereby males fly to and alight on the decoys as they would on real females. Using an industrially scalable nanomolding process, we replicated and evaluated the importance of two features of the outer cuticular surface of the beetle’s wings: structural interference coloration of the elytra by multilayering of the epicuticle and fine-scale surface features consisting of spicules and spines that scatter light into intense strands. Two types of decoys that lacked one or both of these elements were fabricated, one type nano-bioreplicated and the other 3D-printed with no bioreplicated surface nanostructural elements. Both types were colored with green paint. The light-scattering properties of the nano-bioreplicated surfaces were verified by shining a white laser on the decoys in a dark room and projecting the scattering pattern onto a white surface. Regardless of the coloration mechanism, the nano-bioreplicated decoys evoked the complete attraction and landing sequence of Agrilus males. In contrast, males made brief flying approaches toward the decoys without nanostructured features, but diverted away before alighting on them. The nano-bioreplicated decoys were also electroconductive, a feature used on traps such that beetles alighting onto them were stunned, killed, and collected. PMID:25225359

Singlet oxygen generation on porous superhydrophobic surfaces: effect of gas flow and sensitizer wetting on trapping efficiency.

PubMed

Zhao, Yuanyuan; Liu, Yang; Xu, Qianfeng; Barahman, Mark; Bartusik, Dorota; Greer, Alexander; Lyons, Alan M

2014-11-13

We describe physical-organic studies of singlet oxygen generation and transport into an aqueous solution supported on superhydrophobic surfaces on which silicon-phthalocyanine (Pc) particles are immobilized. Singlet oxygen ((1)O2) was trapped by a water-soluble anthracene compound and monitored in situ using a UV-vis spectrometer. When oxygen flows through the porous superhydrophobic surface, singlet oxygen generated in the plastron (i.e., the gas layer beneath the liquid) is transported into the solution within gas bubbles, thereby increasing the liquid-gas surface area over which singlet oxygen can be trapped. Higher photooxidation rates were achieved in flowing oxygen, as compared to when the gas in the plastron was static. Superhydrophobic surfaces were also synthesized so that the Pc particles were located in contact with, or isolated from, the aqueous solution to evaluate the relative effectiveness of singlet oxygen generated in solution and the gas phase, respectively; singlet oxygen generated on particles wetted by the solution was trapped more efficiently than singlet oxygen generated in the plastron, even in the presence of flowing oxygen gas. A mechanism is proposed that explains how Pc particle wetting, plastron gas composition and flow rate as well as gas saturation of the aqueous solution affect singlet oxygen trapping efficiency. These stable superhydrophobic surfaces, which can physically isolate the photosensitizer particles from the solution may be of practical importance for delivering singlet oxygen for water purification and medical devices.

Grooved impactor and inertial trap for sampling inhalable particulate matter

DOEpatents

Loo, Billy W.

1984-01-01

An inertial trap and grooved impactor for providing a sharp cutoff for particles over 15 microns from entering an inhalable particulate sampler. The impactor head has a tapered surface and is provided with V-shaped grooves. The tapered surface functions for reducing particle blow-off or reentrainment while the grooves prevent particle bounce. Water droplets and any resuspended material over the 15 micron size are collected by the inertial trap and deposited in a reservoir associated with the impactor.

Rigid particulate matter sensor

DOEpatents

Hall, Matthew [Austin, TX

2011-02-22

A sensor to detect particulate matter. The sensor includes a first rigid tube, a second rigid tube, a detection surface electrode, and a bias surface electrode. The second rigid tube is mounted substantially parallel to the first rigid tube. The detection surface electrode is disposed on an outer surface of the first rigid tube. The detection surface electrode is disposed to face the second rigid tube. The bias surface electrode is disposed on an outer surface of the second rigid tube. The bias surface electrode is disposed to face the detection surface electrode on the first rigid tube. An air gap exists between the detection surface electrode and the bias surface electrode to allow particulate matter within an exhaust stream to flow between the detection and bias surface electrodes.

Pronounced photogating effect in atomically thin WSe2 with a self-limiting surface oxide layer

NASA Astrophysics Data System (ADS)

Yamamoto, Mahito; Ueno, Keiji; Tsukagoshi, Kazuhito

2018-04-01

The photogating effect is a photocurrent generation mechanism that leads to marked responsivity in two-dimensional (2D) semiconductor-based devices. A key step to promote the photogating effect in a 2D semiconductor is to integrate it with a high density of charge traps. Here, we show that self-limiting surface oxides on atomically thin WSe2 can serve as effective electron traps to facilitate p-type photogating. By examining the gate-bias-induced threshold voltage shift of a p-type transistor based on single-layer WSe2 with surface oxide, the electron trap density and the trap rate of the oxide are determined to be >1012 cm-2 and >1010 cm-2 s-1, respectively. White-light illumination on an oxide-covered 4-layer WSe2 transistor leads to the generation of photocurrent, the magnitude of which increases with the hole mobility. During illumination, the photocurrent evolves on a timescale of seconds, and a portion of the current persists even after illumination. These observations indicate that the photogenerated electrons are trapped deeply in the surface oxide and effectively gate the underlying WSe2. Owing to the pronounced photogating effect, the responsivity of the oxide-covered WSe2 transistor is observed to exceed 3000 A/W at an incident optical power of 1.1 nW, suggesting the effectiveness of surface oxidation in facilitating the photogating effect in 2D semiconductors.

Patterned structures of graphene and graphitic carbon and methods for their manufacture

DOEpatents

Polsky, Ronen; Xiao, Xiaoyin; Burckel, David Bruce; Wheeler, David R.; Brozik, Susan M.; Beechem, Thomas Edwin

2017-01-03

A patterned graphene or graphitic body is produced by providing a three-dimensionally patterned carbonaceous body; coating the body with a catalytic metal whereby is formed a coating having an inner surface proximal the body and an outer surface distal the body; and annealing the coated body under time and temperature conditions effective to form a graphene or graphitic layer on the outer surface of the catalytic metal coating.

Patterned structures of graphene and graphitic carbon and methods for their manufacture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polsky, Ronen; Xiao, Xiaoyin; Burckel, David Bruce

A patterned graphene or graphitic body is produced by providing a three-dimensionally patterned carbonaceous body; coating the body with a catalytic metal whereby is formed a coating having an inner surface proximal the body and an outer surface distal the body; and annealing the coated body under time and temperature conditions effective to form a graphene or graphitic layer on the outer surface of the catalytic metal coating.

The Characteristics of Fatigue Damage in the Fuselage Riveted Lap Splice Joint

NASA Technical Reports Server (NTRS)

Piascik, Robert S.; Willard, Scott A.

1997-01-01

An extensive data base has been developed to form the physical basis for new analytical methodology to predict the onset of widespread fatigue damage in the fuselage lap splice joint. The results of detailed destructive examinations have been cataloged to describe the physical nature of MSD in the lap splice joint. ne catalog includes a detailed description, e.g., crack initiation, growth rates, size, location, and fracture morphology, of fatigue damage in the fuselage lap splice joint structure. Detailed examinations were conducted on a lap splice joint panel removed from a full scale fuselage test article after completing a 60,000 cycle pressure test. The panel contained a four bay region that exhibited visible outer skin cracks and regions of crack link-up along the upper rivet row. Destructive examinations revealed undetected fatigue damage in the outer skin, inner skin, and tear strap regions. Outer skin fatigue cracks were found to initiate by fretting damage along the faying surface. The cracks grew along the faying surface to a length equivalent to two to three skin thicknesses before penetrating the outboard surface of the outer skin. Analysis of fracture surface marker bands produced during full scale testing revealed that all upper rivet row fatigue cracks contained in a dim bay region grow at similar rates; this important result suggests that fracture mechanics based methods can be used to predict the growth of outer skin fatigue cracks in lap splice structure. Results are presented showing the affects of MSD and out-of-plane pressure loads on outer skin crack link-up.

Target electron ionization in Li2+-Li collisions: A multi-electron perspective

NASA Astrophysics Data System (ADS)

Śpiewanowski, M. D.; Gulyás, L.; Horbatsch, M.; Kirchner, T.

2015-05-01

The recent development of the magneto-optical trap reaction-microscope has opened a new chapter for detailed investigations of charged-particle collisions from alkali atoms. It was shown that energy-differential cross sections for ionization from the outer-shell in O8+-Li collisions at 1500 keV/amu can be readily explained with the single-active-electron approximation. Understanding of K-shell ionization, however, requires incorporating many-electron effects. An ionization-excitation process was found to play an important role. We present a theoretical study of target electron removal in Li2+-Li collisions at 2290 keV/amu. The results indicate that in outer-shell ionization a single-electron process plays the dominant part. However, the K-shell ionization results are more difficult to interpret. On one hand, we find only weak contributions from multi-electron processes. On the other hand, a large discrepancy between experimental and single-particle theoretical results indicate that multi-electron processes involving ionization from the outer shell may be important for a complete understanding of the process. Work supported by NSERC, Canada and the Hungarian Scientific Research Fund.

Model for thickness dependence of radiation charging in MOS structures

NASA Technical Reports Server (NTRS)

Viswanathan, C. R.; Maserjian, J.

1976-01-01

The model considers charge buildup in MOS structures due to hole trapping in the oxide and the creation of sheet charge at the silicon interface. The contribution of hole trapping causes the flatband voltage to increase with thickness in a manner in which square and cube dependences are limiting cases. Experimental measurements on samples covering a 200 - 1000 A range of oxide thickness are consistent with the model, using independently obtained values of hole-trapping parameters. An important finding of our experimental results is that a negative interface charge contribution due to surface states created during irradiation compensates most of the positive charge in the oxide at flatband. The tendency of the surface states to 'track' the positive charge buildup in the oxide, for all thicknesses, applies both in creation during irradiation and in annihilation during annealing. An explanation is proposed based on the common defect origin of hole traps and potential surface states.

Trapped atoms along nanophotonic resonators

NASA Astrophysics Data System (ADS)

Fields, Brian; Kim, May; Chang, Tzu-Han; Hung, Chen-Lung

2017-04-01

Many-body systems subject to long-range interactions have remained a very challenging topic experimentally. Ultracold atoms trapped in extreme proximity to the surface of nanophotonic structures provides a dynamic system combining the strong atom-atom interactions mediated by guided mode photons with the exquisite control implemented with trapped atom systems. The hybrid system promises pair-wise tunability of long-range interactions between atomic pseudo spins, allowing studies of quantum magnetism extending far beyond nearest neighbor interactions. In this talk, we will discuss our current status developing high quality nanophotonic ring resonators, engineered on CMOS compatible optical chips with integrated nanostructures that, in combination with a side illuminating beam, can realize stable atom traps approximately 100nm above the surface. We will report on our progress towards loading arrays of cold atoms near the surface of these structures and studying atom-atom interaction mediated by photons with high cooperativity.

Surface Traps in Colloidal Quantum Dots: A Combined Experimental and Theoretical Perspective

PubMed Central

2017-01-01

Surface traps are ubiquitous to nanoscopic semiconductor materials. Understanding their atomistic origin and manipulating them chemically have capital importance to design defect-free colloidal quantum dots and make a leap forward in the development of efficient optoelectronic devices. Recent advances in computing power established computational chemistry as a powerful tool to describe accurately complex chemical species and nowadays it became conceivable to model colloidal quantum dots with realistic sizes and shapes. In this Perspective, we combine the knowledge gathered in recent experimental findings with the computation of quantum dot electronic structures. We analyze three different systems: namely, CdSe, PbS, and CsPbI3 as benchmark semiconductor nanocrystals showing how different types of trap states can form at their surface. In addition, we suggest experimental healing of such traps according to their chemical origin and nanocrystal composition. PMID:28972763

46 CFR 42.13-15 - Definitions of terms.

Code of Federal Regulations, 2013 CFR

2013-10-01

... line of the frame in a vessel with a metal shell and to the outer surface of the hull in a vessel with... vessel with a metal shell, and is the volume of displacement to the outer surface of the hull in a vessel... between the machinery space and peak bulkheads and continuous athwartships. When this lower deck is...

46 CFR 42.13-15 - Definitions of terms.

Code of Federal Regulations, 2012 CFR

2012-10-01

... line of the frame in a vessel with a metal shell and to the outer surface of the hull in a vessel with... vessel with a metal shell, and is the volume of displacement to the outer surface of the hull in a vessel... between the machinery space and peak bulkheads and continuous athwartships. When this lower deck is...

Integrated gas turbine engine-nacelle

NASA Technical Reports Server (NTRS)

Adamson, A. P.; Sargisson, D. F.; Stotler, C. L., Jr. (Inventor)

1977-01-01

A nacelle for use with a gas turbine engine is presented. An integral webbed structure resembling a spoked wheel for rigidly interconnecting the nacelle and engine, provides lightweight support. The inner surface of the nacelle defines the outer limits of the engine motive fluid flow annulus while the outer surface of the nacelle defines a streamlined envelope for the engine.

First-principles calculation of the geometric and electronic structure of the Be(0001) surface

NASA Astrophysics Data System (ADS)

Feibelman, Peter J.

1992-07-01

Linearized-augmented-plane-wave calculations for a nine-layer Be(0001) slab agree with the unusual experimental finding of a substantial outer-layer expansion relative to the truncated bulk lattice. They imply that the separation between the outer two layers should be 3.9% larger than in the bulk, while the second- to third-layer separation should be 2.2% larger. The surface expansion is accompanied by demotion of pσ to s electrons on outer-layer Be's. The surface Be's loss of three neighbors makes the energy cost of s- to pσ-electron promotion, which is necessary for the formation of strong bonds to the next layer down, less profitable than in the bulk.

Proton-Induced Trap States, Injection and Recombination Dynamics in Water-Splitting Dye-Sensitized Photoelectrochemical Cells.

PubMed

McCool, Nicholas S; Swierk, John R; Nemes, Coleen T; Saunders, Timothy P; Schmuttenmaer, Charles A; Mallouk, Thomas E

2016-07-06

Water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) utilize a sensitized metal oxide and a water oxidation catalyst in order to generate hydrogen and oxygen from water. Although the Faradaic efficiency of water splitting is close to unity, the recombination of photogenerated electrons with oxidized dye molecules causes the quantum efficiency of these devices to be low. It is therefore important to understand recombination mechanisms in order to develop strategies to minimize them. In this paper, we discuss the role of proton intercalation in the formation of recombination centers. Proton intercalation forms nonmobile surface trap states that persist on time scales that are orders of magnitude longer than the electron lifetime in TiO2. As a result of electron trapping, recombination with surface-bound oxidized dye molecules occurs. We report a method for effectively removing the surface trap states by mildly heating the electrodes under vacuum, which appears to primarily improve the injection kinetics without affecting bulk trapping dynamics, further stressing the importance of proton control in WS-DSPECs.

Impurity Content Optimization to Maximize Q-Factors of Superconducting Resonators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinello, Martina; Checchin, Mattia; Grassellino, Anna

2017-05-01

Quality factor of superconducting radio-frequency (SRF) cavities is degraded whenever magnetic flux is trapped in the cavity walls during the cooldown. In this contribution we study how the trapped flux sensitivity, defined as the trapped flux surface resistance normalized for the amount of trapped flux, depends on the mean free path. A systematic study of a variety of 1.3 GHz cavities with different surface treatments (EP, 120 C bake and different N-doping) is carried out. A bell shaped trend appears for the range of mean free path studied. Over-doped cavities fall at the maximum of this curve defining the largestmore » values of sensitivity. In addition, we have studied the trend of the BCS surface resistance contribution as a function of mean free path, showing that N-doped cavities follow close to the theoretical minimum. Adding these results together we show that the 2/6 N-doping treatment gives the highest Q-factor values at 2 K and 16 MV/m, as long as the magnetic field fully trapped during the cavity cooldown is lower than 10 mG.« less

Coastal dynamics off Northwest Iberia during a stormy winter period

NASA Astrophysics Data System (ADS)

Otero, Pablo; Ruiz-Villarreal, Manuel; García-García, Luz; González-Nuevo, Gonzalo; Cabanas, Jose Manuel

2013-01-01

The consequences of a stormy winter period (2009/2010) on the shelf and coastal dynamics off Northwest Iberia are analysed by using model results in combination with the set of available observations in the frame of the Iberian Margin Ocean Observatory (RAIA), a cross-border infrastructure among North Portugal and Galicia (Spain). During the study winter, the frequent arrival of weather fronts forced river plumes to flow along the inner shelf in a fast (>1 m s-1) jet-like structure. The buoyant current strongly influenced the outer rías, the name of the estuaries in the region, where a strong decay of surface salinity (<10.5) has been observed. Once the weather front has passed, the wind reversal forced the offshore expansion of river plumes and also the development of a winter upwelling event. Thermohaline patterns in both model and observations revealed an intrusion of warm (>15 °C) and salty (>35.9) waters into the rías associated with the Iberian Poleward Current. Finally, some Lagrangian modelling experiments were performed to analyse the transport ability of the plume and the effect that could have had in the biological material trapped on it. The experiments reveal that an overall northward displacement of surface particles will be expected after several alternate wind events.

Thermally actuated magnetization flux pump in single-grain YBCO bulk

NASA Astrophysics Data System (ADS)

Yan, Yu; Li, Quan; Coombs, T. A.

2009-10-01

Recent progress in material processing has proved that high temperature superconductors (HTS) have a great potential to trap large magnetic fields at cryogenic temperatures. For example, HTS are widely used in MRI scanners and in magnetic bearings. However, using traditional ways to magnetize, the YBCO will always need the applied field to be as high as the expected field on the superconductor or much higher than it, leading to a much higher cost than that of using permanent magnets. In this paper, we find a method of YBCO magnetization in liquid nitrogen that only requires the applied field to be at the level of a permanent magnet. Moreover, rather than applying a pulsed high current field on the YBCO, we use a thermally actuated material (gadolinium) as an intermedia and create a travelling magnetic field through it by changing the partial temperature so that the partial permeability is changed to build up the magnetization of the YBCO gradually after multiple pumps. The gadolinium bulk is located between the YBCO and the permanent magnet and is heated and cooled repeatedly from the outer surface to generate a travelling thermal wave inwards. In the subsequent experiment, an obvious accumulation of the flux density is detected on the surface of the YBCO bulk.

Serendipity in the Outer Solar System

NASA Astrophysics Data System (ADS)

Spencer, J. R.

2016-12-01

Science does not proceed in straight lines. As important as our proposals and traceability matrices are, the most interesting discoveries have often been ones that were never anticipated in those documents. In my own career, surplus telescope time at the end of a night resulted in the first observations of the remarkable suite of trapped volatiles on the surfaces of the icy Galilean satellites. A mis-targeted Hubble observation led to a chemical inventory of Io's volcanic plumes and a window into its interior. Routine thermal scans of Saturn's moons by Cassini revealed the physical reworking of icy surfaces by magnetospheric bombardment, and led to the first detection of endogenic heat from an icy world. Mysterious gaps in our scans of that world, Enceladus, pointed the way to a tenfold increase in the spatial resolution of the thermal images. Most recently, concerns about the impact hazard to the New Horizons spacecraft led us to the discovery of the bizarre rotational dynamics of Pluto's small moons. As New Horizons continues its explorations deeper into the Kuiper Belt, and we plan follow-up missions to some of the strangest places discovered in the first phases of solar system exploration, we should continue to be prepared for the wonderful surprises that our data will inevitably send our way.

Single-molecule dynamics in nanofabricated traps

NASA Astrophysics Data System (ADS)

Cohen, Adam

2009-03-01

The Anti-Brownian Electrokinetic trap (ABEL trap) provides a means to immobilize a single fluorescent molecule in solution, without surface attachment chemistry. The ABEL trap works by tracking the Brownian motion of a single molecule, and applying feedback electric fields to induce an electrokinetic motion that approximately cancels the Brownian motion. We present a new design for the ABEL trap that allows smaller molecules to be trapped and more information to be extracted from the dynamics of a single molecule than was previously possible. In particular, we present strategies for extracting dynamically fluctuating mobilities and diffusion coefficients, as a means to probe dynamic changes in molecular charge and shape. If one trapped molecule is good, many trapped molecules are better. An array of single molecules in solution, each immobilized without surface attachment chemistry, provides an ideal test-bed for single-molecule analyses of intramolecular dynamics and intermolecular interactions. We present a technology for creating such an array, using a fused silica plate with nanofabricated dimples and a removable cover for sealing single molecules within the dimples. With this device one can watch the shape fluctuations of single molecules of DNA or study cooperative interactions in weakly associating protein complexes.

Recent progress in the understanding of H transport and trapping in W

NASA Astrophysics Data System (ADS)

Schmid, K.; Bauer, J.; Schwarz-Selinger, T.; Markelj, S.; Toussaint, U. v.; Manhard, A.; Jacob, W.

2017-12-01

The retention of hydrogen isotopes (HIs) (H, D and T) in the first, plasma exposed wall is one of the key concerns for the operation of future long pulse fusion devices. It affects the particle-, momentum- and energy balance in the scrape off layer as well as the retention of HIs and their permeation into the coolant. The currently accepted picture that is used for interpreting current laboratory and tokamak experiments is that of diffusion hindered by trapping at lattice defects. This paper summarises recent results that show that this current picture of how HIs are transported and retained in W needs to be extended: the modification of the surface (e.g. blistering) can lead to the formation of fast loss channels for near surface HIs. Trapping at single occupancy traps with fixed de-trapping energy fails to explain isotope exchange experiments, instead a trapping model with multi occupancy traps and fill level dependent de-trapping energies is required. The presence of interstitial impurities like N or C may affect the transport of solute HI. The presence of HIs during damage creation by e.g. neutrons stabilises defects and reduces defect annealing at elevated temperatures.

Plasmonic trapping potentials for cold atoms

NASA Astrophysics Data System (ADS)

Mildner, Matthias; Horrer, Andreas; Fleischer, Monika; Zimmermann, Claus; Slama, Sebastian

2018-07-01

This paper reports on conceptual and experimental work towards the realization of plasmonic surface traps for cold atoms. The trapping mechanism is based on the combination of a repulsive and an attractive potential generated by evanescent light waves that are plasmonically enhanced. The strength of enhancement can be locally manipulated via the thickness of a metal nanolayer deposited on top of a dielectric substrate. Thus, in principle the trapping geometry can be predefined by the metal layer design. We present simulations of a plasmonic lattice potential using a gold grating with sinusoidally modulated thickness. Experimentally, a first plasmonic test structure is presented and characterized. Furthermore, the surface potential landscape is detected by reflecting ultracold atom clouds from the test structure revealing the influence of both evanescent waves. A parameter range is identified where stable traps can be expected.

Microbial community structure and function on sinking particles in the North Pacific Subtropical Gyre

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fontanez, Kristina M.; Eppley, John M.; Samo, Ty J.

Sinking particles mediate the transport of carbon and energy to the deep-sea, yet the specific microbes associated with sedimenting particles in the ocean's interior remain largely uncharacterized. In this study, we used particle interceptor traps (PITs) to assess the nature of particle-associated microbial communities collected at a variety of depths in the North Pacific Subtropical Gyre. Comparative metagenomics was used to assess differences in microbial taxa and functional gene repertoires in PITs containing a preservative (poisoned traps) compared to preservative-free traps where growth was allowed to continue in situ (live traps). Live trap microbial communities shared taxonomic and functional similaritiesmore » with bacteria previously reported to be enriched in dissolved organic matter (DOM) microcosms (e.g., Alteromonas and Methylophaga), in addition to other particle and eukaryote-associated bacteria (e.g., Flavobacteriales and Pseudoalteromonas). Poisoned trap microbial assemblages were enriched in Vibrio and Campylobacterales likely associated with eukaryotic surfaces and intestinal tracts as symbionts, pathogens, or saprophytes. The functional gene content of microbial assemblages in poisoned traps included a variety of genes involved in virulence, anaerobic metabolism, attachment to chitinaceaous surfaces, and chitin degradation. The presence of chitinaceaous surfaces was also accompanied by the co-existence of bacteria which encoded the capacity to attach to, transport and metabolize chitin and its derivatives. Distinctly different microbial assemblages predominated in live traps, which were largely represented by copiotrophs and eukaryote-associated bacterial communities. Predominant sediment trap-assocaited eukaryotic phyla included Dinoflagellata, Metazoa (mostly copepods), Protalveolata, Retaria, and Stramenopiles. In conclusion, these data indicate the central role of eukaryotic taxa in structuring sinking particle microbial assemblages, as well as the rapid responses of indigenous microbial species in the degradation of marine particulate organic matter (POM) in situ in the ocean's interior.« less

Microbial community structure and function on sinking particles in the North Pacific Subtropical Gyre

DOE PAGES

Fontanez, Kristina M.; Eppley, John M.; Samo, Ty J.; ...

2015-05-19

Sinking particles mediate the transport of carbon and energy to the deep-sea, yet the specific microbes associated with sedimenting particles in the ocean's interior remain largely uncharacterized. In this study, we used particle interceptor traps (PITs) to assess the nature of particle-associated microbial communities collected at a variety of depths in the North Pacific Subtropical Gyre. Comparative metagenomics was used to assess differences in microbial taxa and functional gene repertoires in PITs containing a preservative (poisoned traps) compared to preservative-free traps where growth was allowed to continue in situ (live traps). Live trap microbial communities shared taxonomic and functional similaritiesmore » with bacteria previously reported to be enriched in dissolved organic matter (DOM) microcosms (e.g., Alteromonas and Methylophaga), in addition to other particle and eukaryote-associated bacteria (e.g., Flavobacteriales and Pseudoalteromonas). Poisoned trap microbial assemblages were enriched in Vibrio and Campylobacterales likely associated with eukaryotic surfaces and intestinal tracts as symbionts, pathogens, or saprophytes. The functional gene content of microbial assemblages in poisoned traps included a variety of genes involved in virulence, anaerobic metabolism, attachment to chitinaceaous surfaces, and chitin degradation. The presence of chitinaceaous surfaces was also accompanied by the co-existence of bacteria which encoded the capacity to attach to, transport and metabolize chitin and its derivatives. Distinctly different microbial assemblages predominated in live traps, which were largely represented by copiotrophs and eukaryote-associated bacterial communities. Predominant sediment trap-assocaited eukaryotic phyla included Dinoflagellata, Metazoa (mostly copepods), Protalveolata, Retaria, and Stramenopiles. In conclusion, these data indicate the central role of eukaryotic taxa in structuring sinking particle microbial assemblages, as well as the rapid responses of indigenous microbial species in the degradation of marine particulate organic matter (POM) in situ in the ocean's interior.« less

Laser Cooling and Trapping of Neutral Strontium for Spectroscopic Measurements of Casimir-Polder Potentials

NASA Astrophysics Data System (ADS)

Cook, Eryn C.

Casimir and Casimir-Polder effects are forces between electrically neutral bodies and particles in vacuum, arising entirely from quantum fluctuations. The modification to the vacuum electromagnetic-field modes imposed by the presence of any particle or surface can result in these mechanical forces, which are often the dominant interaction at small separations. These effects play an increasingly critical role in the operation of micro- and nano-mechanical systems as well as miniaturized atomic traps for precision sensors and quantum-information devices. Despite their fundamental importance, calculations present theoretical and numeric challenges, and precise atom-surface potential measurements are lacking in many geometric and distance regimes. The spectroscopic measurement of Casimir-Polder-induced energy level shifts in optical-lattice trapped atoms offers a new experimental method to probe atom-surface interactions. Strontium, the current front-runner among optical frequency metrology systems, has demonstrated characteristics ideal for such precision measurements. An alkaline earth atom possessing ultra-narrow intercombination transitions, strontium can be loaded into an optical lattice at the "magic" wavelength where the probe transition is unperturbed by the trap light. Translation of the lattice will permit controlled transport of tightly-confined atomic samples to well-calibrated atom-surface separations, while optical transition shifts serve as a direct probe of the Casimir-Polder potential. We have constructed a strontium magneto-optical trap (MOT) for future Casimir-Polder experiments. This thesis will describe the strontium apparatus, initial trap performance, and some details of the proposed measurement procedure.

All-reflective optical target illumination system with high numerical aperture

DOEpatents

Thomas, Carlton E.; Sigler, Robert D.; Hoeger, John G.

1979-01-01

An all-reflective optical system for providing illumination of a target focal region at high numerical aperture from a pair of confluent collimated light beams. The collimated beams are each incident upon an associated concave eccentric pupil paraboloidal reflective surface, and thereby each focused through an opening in an associated outer ellipsoidal reflective surface onto a plane reflector. Each beam is reflected by its associated plane reflector onto the opposing concave surface of the outer ellipsoids to be focused through an opening in the plane surface onto an opposing inner concave ellipsoidal reflective surface, and thence onto the target region.

Reproductive resource partitioning in two sympatric Goniothalamus species (Annonaceae) from Borneo: floral biology, pollinator trapping and plant breeding system

PubMed Central

Lau, Jenny Y. Y.; Pang, Chun-Chiu; Ramsden, Lawrence; Saunders, Richard M. K.

2016-01-01

The floral phenology, pollination ecology and breeding systems of two sympatric early-divergent angiosperms, Goniothalamus tapisoides and G. suaveolens (Annonaceae) are compared. The flowers are protogynous and morphologically similar, with anthesis over 23–25 h. Both species are predominantly xenogamous and pollinated by small beetles: G. tapisoides mainly by Curculionidae and G. suaveolens mainly by Nitidulidae. Coevolution and reproductive resource partitioning, reducing interspecific pollen transfer, is achieved by temporal isolation, due to contrasting floral phenologies; and ethological isolation, due to contrasting floral scents that contain attractants specific to the two beetle families. Analysis of floral scents revealed three volatiles (3-methylbutyl acetate, ethyl hexanoate and 2-phenylethanol) that are known to be nitidulid attractants in the floral scent of G. suaveolens, but absent from that of G. tapisoides. An effective pollinator trapping mechanism is demonstrated for both species, representing the first such report for the family. Trapping is achieved by the compression of the outer petals against the apertures between the inner petals. This trapping mechanism is likely to be a key evolutionary innovation for Goniothalamus, increasing pollination efficiency by increasing pollen loading on beetles during the staminate phase, promoting effective interfloral pollinator movements, and increasing seed-set by enabling rapid turn-over of flowers. PMID:27767040

Reproductive resource partitioning in two sympatric Goniothalamus species (Annonaceae) from Borneo: floral biology, pollinator trapping and plant breeding system.

PubMed

Lau, Jenny Y Y; Pang, Chun-Chiu; Ramsden, Lawrence; Saunders, Richard M K

2016-10-21

The floral phenology, pollination ecology and breeding systems of two sympatric early-divergent angiosperms, Goniothalamus tapisoides and G. suaveolens (Annonaceae) are compared. The flowers are protogynous and morphologically similar, with anthesis over 23-25 h. Both species are predominantly xenogamous and pollinated by small beetles: G. tapisoides mainly by Curculionidae and G. suaveolens mainly by Nitidulidae. Coevolution and reproductive resource partitioning, reducing interspecific pollen transfer, is achieved by temporal isolation, due to contrasting floral phenologies; and ethological isolation, due to contrasting floral scents that contain attractants specific to the two beetle families. Analysis of floral scents revealed three volatiles (3-methylbutyl acetate, ethyl hexanoate and 2-phenylethanol) that are known to be nitidulid attractants in the floral scent of G. suaveolens, but absent from that of G. tapisoides. An effective pollinator trapping mechanism is demonstrated for both species, representing the first such report for the family. Trapping is achieved by the compression of the outer petals against the apertures between the inner petals. This trapping mechanism is likely to be a key evolutionary innovation for Goniothalamus, increasing pollination efficiency by increasing pollen loading on beetles during the staminate phase, promoting effective interfloral pollinator movements, and increasing seed-set by enabling rapid turn-over of flowers.

Influence of long-range forces and capillarity on the function of underwater superoleophobic wrinkled surfaces.

PubMed

Owais, Ahmed; Smith-Palmer, Truis; Gentle, Angus; Neto, Chiara

2018-06-26

Underwater superoleophobic surfaces can be considered a particular type of lubricant-infused surface, that have anti-fouling properties by virtue of a trapped water layer that repels oils. However, as their function relies on a water layer being trapped in the surface roughness, it is crucial to understand the factors that determine the layer stability. In this work, the forces that are responsible for the stability of thin liquid films within structured surfaces were quantified, and the conclusions were tested against the performance of wrinkled surfaces as underwater superoleophobic coatings. Here, the system studied was a family of wrinkled surfaces made of hydrophilic poly(4-vinylpyridine) (P4VP), whereby the wrinkle width could be controllably tuned in the range 90 nm to 8000 nm. The van der Waals free energy was quantified and the capillary forces trapping water in the surface micro- and nano-wrinkle structure were estimated. P4VP surfaces with micro-scale wrinkles had underwater superoleophobic properties, and low adhesion to different oils with droplet roll-off angle below 6° ± 1°. Despite the van der Waals free energy of the system pointing to the dewetting of a water film under oil on top of a smooth P4VP film, the wrinkled structure is sufficient to induce a Cassie state with a trapped water layer. The micro-scale wrinkles (average width 4-12 μm) were found to be particularly effective in the trapping of the water in a Cassie non-adhesive state. The P4VP wrinkled surfaces are superamphiphobic, as when they were first infused with oil, and then exposed to a droplet of water under oil, they exhibited superhydrophobic behavior. The P4VP wrinkles have the additional useful feature of being transparent underwater, which makes them useful candidates for the protection of underwater cameras and sensors.

Update on Science Results from CubeSat: Colorado Student Space Weather Experiment (CSSWE)

NASA Astrophysics Data System (ADS)

Li, X.; Schiller, Q.; Blum, L. W.; Califf, S.; Zhao, H.; Jaynes, A. N.; Tu, W.; Turner, D. L.; Gerhardt, D.; Palo, S. E.; Selesnick, R.; Kanekal, S. G.; Baker, D. N.; Fennell, J. F.; Blake, J. B.; Looper, M. D.; Reeves, G. D.; Spence, H.

2013-12-01

Measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) onboard CSSWE, which was launched into a highly inclined (65 deg) low Earth orbit on 13 September 2012, are analyzed along with measurements from the Relativistic Electron and Proton Telescope (REPT) and the Magnetic Electron Ion Spectrometer (MagEIS) instruments aboard the Van Allen Probes, which are in a low inclination (10 deg) geo-transfer-like orbit. Both REPT and MagEIS measure the full distribution of energetic electrons as they traverse the heart of the outer radiation belt. However, due to the small equatorial loss cone (only a few deg), it is difficult for REPT and MagEIS to directly determine which electrons will precipitate into the atmosphere, a major loss process. REPTile, a miniaturized version of REPT, measures the fraction of the total electron population that has small enough equatorial pitch angles to reach the altitude, 480km x 780 km, of CSSWE, thus measuring the precipitating population as well as the trapped and quasi-trapped populations. These newly available measurements provide an unprecedented opportunity to investigate the source, loss, and energization processes that are responsible for the dynamic behavior of outer radiation belt electrons. The focus of presentation will be on the characteristics of relativistic electrons measured by REPTile during the October 2012 storms, and results during other events will also be summarized.

Microfabricated Microwave-Integrated Surface Ion Trap

NASA Astrophysics Data System (ADS)

Revelle, Melissa C.; Blain, Matthew G.; Haltli, Raymond A.; Hollowell, Andrew E.; Nordquist, Christopher D.; Maunz, Peter

2017-04-01

Quantum information processing holds the key to solving computational problems that are intractable with classical computers. Trapped ions are a physical realization of a quantum information system in which qubits are encoded in hyperfine energy states. Coupling the qubit states to ion motion, as needed for two-qubit gates, is typically accomplished using Raman laser beams. Alternatively, this coupling can be achieved with strong microwave gradient fields. While microwave radiation is easier to control than a laser, it is challenging to precisely engineer the radiated microwave field. Taking advantage of Sandia's microfabrication techniques, we created a surface ion trap with integrated microwave electrodes with sub-wavelength dimensions. This multi-layered device permits co-location of the microwave antennae and the ion trap electrodes to create localized microwave gradient fields and necessary trapping fields. Here, we characterize the trap design and present simulated microwave performance with progress towards experimental results. This research was funded, in part, by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA).

Method for deploying and recovering a wave energy converter

DOEpatents

Mundon, Timothy R

2017-05-23

A system for transporting a buoy and a heave plate. The system includes a buoy and a heave plate. An outer surface of the buoy has a first geometrical shape. A surface of the heave plate has a geometrical shape complementary to the first geometrical shape of the buoy. The complementary shapes of the buoy and the heave plate facilitate coupling of the heave plate to the outer surface of the buoy in a transport mode.

Positron states and annihilation characteristics of surface-trapped positrons at the oxidized Cu(110) surface

NASA Astrophysics Data System (ADS)

Fazleev, N. G.; Olenga, Antoine; Weiss, A. H.

2013-03-01

The process by which oxide layers are formed on metal surfaces is still not well understood. In this work we present the results of theoretical studies of positron states and annihilation characteristics of surface-trapped positrons at the oxidized Cu(110) surface. An ab-initio investigation of stability and associated electronic properties of different adsorption phases of oxygen on Cu(110) has been performed on the basis of density functional theory and using DMOl3 code. The changes in the positron work function and the surface dipole moment when oxygen atoms occupy on-surface and sub-surface sites have been attributed to charge redistribution within the first two layers, buckling effects within each layer and interlayer expansion. The computed positron binding energy, positron surface state wave function, and annihilation probabilities of surface trapped positrons with relevant core electrons demonstrate their sensitivity to oxygen coverage, elemental content, atomic structure of the topmost layers of surfaces, and charge transfer effects. Theoretical results are compared with experimental data obtained from studies of oxidized transition metal surfaces using positron annihilation induced Auger electron spectroscopy. This work was supported in part by the National Science Foundation Grant DMR-0907679.

Processing of ammonia-containing ices by heavy ions and its relevance to outer Solar System surfaces

NASA Astrophysics Data System (ADS)

Pilling, Sergio; Seperuelo Duarte, Eduardo; da Silveira, Enio F.; Domaracka, Alicja; Balanzat, Emmanuel; Rothard, Hermann; Boduch, Philippe

Ammonia-containing ices have been detected or postulated as important components of the icy surfaces of planetary satellites (e.g. Enceladus, Miranda), in the outer Solar System objects (e.g. Charon, Quaoar) and in Oort cloud comets. We present experimental studies of the interaction of heavy, highly-charged, and energetic ions with ammonia-containing ices (pure NH3 ; NH3 :CO; NH3 :H2 O and NH3 :H2 O:CO) in an attempt to simulate the physical chemistry induced by heavy-ion cosmic rays and heavy-ion solar wind particles at outer Solar System surfaces. The measurements were performed inside a high vacuum chamber at the heavy-ion accelerator GANIL (Grand Accelerateur National d'Ions Lourds) in Caen, France. The gas samples were deposited onto a polished CsI substrate previously cooled to 13 K. In-situ analysis was performed by a Fourier transform infrared spectrometer (FTIR) at different ion fluences. The dissociation cross-section and sputtering yield of ammonia and other ice compounds have been determined. Half-life of frozen ammonia due to heavy ion bombardment at different Solar System surfaces has been estimated. Radiolysis products have been identified and their implications for the chemistry on outer Solar System surfaces are discussed.

COSMIC RAYS AND COSMIC SPACE (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vernova, S.N.

1960-08-01

An account is given of recent studies of cosmic rays utilizing both earthbound stations and artificial earth satellites. Phenomena recently uncovered by sputniks are described. A description is given of the cosmic ray laboratory of Moscow University. A particle possessing an energy of l0/sup 15/ ev was detected and the equipment and procedure by which this was done are described. mu mesons in a particle shower produced by cosmic rays were detected at a depth of thirty meters underground. The apparatus required in the sputriks for the study of cosmic rays outside the earth's atmosphere is discussed. The equipment inmore » the sputniks launched to date was transistorized; scintillation counters were used to determine particle energies. A description is given of the large burst of radiation detected by the second sputnik on Nov. 7, 1957. This burst was observed only at latitudes of about 50 to 70 degrees north latitude. The third sputnik had a scintillation counter of high sensitivity which detected relatively weak fluxes of electrons. This equipment fixed the location of the high intensity radiation belt around the earth. A typical graph of count rate and energy current versus geographic location is given. Data are given that indicate the coincidence of peak radiation intensities with those regions where the aurora borealis is seen. The radiation belt extends up to approximately 60,000 km from the earth's surface and is bounded by the magnetic lines of force that intersect the earth' s surface at geomagnetic latitudes of 55 deg and 70 deg . The earth's magnetic field traps these particles and holds them in an orbit that follows magnetic lines of force and oscillates from the northern to the southern hemisphere for long periods of time. A diagram is given of the trajectory of the first Soviet cosmic rocket and changes in radiation intensity along this trajectory are indicated. A maximum radiation intensity was detected at a distance of 20,000 km from the earth's surface. A diagram compares the data of the first and second Soviet cosmic rockets. It is indicated that radiation intensity in the outer belt varies with time due to variation of emanations from the sun. The energy spectrum of radiation in the outer belt was obtained with gas discharge and scintillation counters installed behind varying amounts of lead, copper, and aluminum shielding. Results are given in a diagram of particle and energy flux versus distance from the earth. The conclusion is reached that the outer radiation belt consists of electrons whose energies vary over six orders of magnitude. However the data from the second rocket indicated that the upper limit of electron energies appears to be 5 Mev. The electron flux is highest at an energy of about 1 Mev. It is pointed out that in the outer radiation belt the energy density of radiation approaches its maximum possible value, that is, the energy density of the earth's magnetic field at that distance. A discussion is given of the inner radiation belt, first described by Van Allen. No evidence of radiation belts about the moon was found. A discussion of the possible origins of the outer radiation belt of the earth and of other radiation belts and magnetic fields in space is given. In the study of solar flares, 1500 radiosonde balloon flights were made during the IGY. These flights established that solar flares are an extreme hazard for space travelers. (TTT)« less

Quantitative evaluation of the relationship between dorsal wall length, sole thickness, and rotation of the distal phalanx in the bovine claw using computed tomography.

PubMed

Tsuka, T; Murahata, Y; Azuma, K; Osaki, T; Ito, N; Okamoto, Y; Imagawa, T

2014-10-01

Computed tomography (CT) was performed on 800 untrimmed claws (400 inner claws and 400 outer claws) of 200 pairs of bovine hindlimbs to investigate the relationships between dorsal wall length and sole thickness, and between dorsal wall length and the relative rotation angle of distal phalanx-to-sole surface (S-D angle). Sole thickness was 3.8 and 4.0 mm at the apex of the inner claws and outer claws, respectively, with dorsal wall lengths <70 mm. These sole thickness values were less than the critical limit of 5 mm, which is associated with a softer surface following thinning of the soles. A sole thickness of 5 mm at the apex was estimated to correlate with dorsal wall lengths of 72.1 and 72.7 mm for the inner and outer claws, respectively. Sole thickness was 6.1 and 6.4 mm at the apex of the inner and outer claws, respectively, with dorsal wall lengths of 75 mm. These sole thickness values were less than the recommended sole thickness of 7 mm based on the protective function of the soles. A sole thickness >7 mm at the apex was estimated to correlate with a dorsal wall length of 79.8 and 78.4mm for the inner and outer claws, respectively. The S-D angles were recorded as anteversions of 2.9° and 4.7° for the inner and outer claws, respectively, with a dorsal wall length of 75 mm. These values indicate that the distal phalanx is likely to have rotated naturally forward toward the sole surface. The distal phalanx rotated backward to the sole surface at 3.2° and 7.6° for inner claws with dorsal wall lengths of 90-99 and ≥100 mm, respectively; and at 3.5° for outer claws with a dorsal wall length ≥100 mm. Dorsal wall lengths of 85.7 and 97.2 mm were estimated to correlate with a parallel positional relationship of the distal phalanx to the sole surface in the inner and outer claws, respectively. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Theoretical characterization on the size-dependent electron and hole trapping activity of chloride-passivated CdSe nanoclusters

NASA Astrophysics Data System (ADS)

Cui, Yingqi; Cui, Xianhui; Zhang, Li; Xie, Yujuan; Yang, Mingli

2018-04-01

Ligand passivation is often used to suppress the surface trap states of semiconductor quantum dots (QDs) for their continuous photoluminescence output. The suppression process is related to the electrophilic/nucleophilic activity of surface atoms that varies with the structure and size of QD and the electron donating/accepting nature of ligand. Based on first-principles-based descriptors and cluster models, the electrophilic/nucleophilic activities of bare and chloride-coated CdSe clusters were studied to reveal the suppression mechanism of Cl-passivated QDs and compared to experimental observations. The surface atoms of bare clusters have higher activity than inner atoms and their activity decreases with cluster size. In the ligand-coated clusters, the Cd atom remains as the electrophilic site, while the nucleophilic site of Se atoms is replaced by Cl atoms. The activities of Cd and Cl atoms in the coated clusters are, however, remarkably weaker than those in bare clusters. Cluster size, dangling atoms, ligand coverage, electronegativity of ligand atoms, and solvent (water) were found to have considerable influence on the activity of surface atoms. The suppression of surface trap states in Cl-passivated QDs was attributed to the reduction of electrophilic/nucleophilic activity of Cd/Se/Cl atoms. Both saturation to under-coordinated surface atoms and proper selection for the electron donating/accepting strength of ligands are crucial for eliminating the charge carrier traps. Our calculations predicted a similar suppressing effect of chloride ligands with experiments and provided a simple but effective approach to assess the charge carrier trapping behaviors of semiconductor QDs.

Turbine exhaust diffuser with region of reduced flow area and outer boundary gas flow

DOEpatents

Orosa, John

2014-03-11

An exhaust diffuser system and method for a turbine engine. The outer boundary may include a region in which the outer boundary extends radially inwardly toward the hub structure and may direct at least a portion of an exhaust flow in the diffuser toward the hub structure. At least one gas jet is provided including a jet exit located on the outer boundary. The jet exit may discharge a flow of gas downstream substantially parallel to an inner surface of the outer boundary to direct a portion of the exhaust flow in the diffuser toward the outer boundary to effect a radially outward flow of at least a portion of the exhaust gas flow toward the outer boundary to balance an aerodynamic load between the outer and inner boundaries.

Gas turbine engine exhaust diffuser including circumferential vane

DOEpatents

Orosa, John A.; Matys, Pawel

2015-05-19

A flow passage defined between an inner and an outer boundary for guiding a fluid flow in an axial direction. A flow control vane is supported at a radial location between the inner and outer boundaries. A fluid discharge opening is provided for discharging a flow of the compressed fluid from a trailing edge of the vane, and a fluid control surface is provided adjacent to the fluid discharge opening and extends in the axial direction at the trailing edge of the vane. The fluid control surface has a curved trailing edge forming a Coanda surface. The fluid discharge opening is selectively provided with a compressed fluid to produce a Coanda effect along the control surface. The Coanda effect has a component in the radial direction effecting a turning of the fluid flow in the flow path radially inward or outward toward one of the inner and outer boundaries.

A multi-technique analysis of deuterium trapping and near-surface precipitate growth in plasma-exposed tungsten

DOE PAGES

Kolasinski, Robert; Shimada, Masashi; Oya, Yasuhisa; ...

2015-08-17

We examine how deuterium becomes trapped in plasma-exposed tungsten and forms near-surface platelet-shaped precipitates. How these bubbles nucleate and grow, as well as the amount of deuterium trapped within, is crucial for interpreting the experimental database. Here, we use a combined experimental/theoretical approach to provide further insight into the underlying physics. With the Tritium Plasma Experiment, we exposed a series of ITER-gradetungsten samples to high flux D plasmas (up to 1.5 × 10 22 m -2 s -1) at temperatures ranging between 103 and 554 °C. Retention of deuterium trapped in the bulk, assessed through thermal desorption spectrometry, reached amore » maximum at 230 °C and diminished rapidly thereafter for T > 300 °C. Post-mortem examination of the surfaces revealed non-uniform growth of bubbles ranging in diameter between 1 and 10 μm over the surface with a clear correlation with grain boundaries. Electron back-scattering diffraction maps over a large area of the surface confirmed this dependence; grains containing bubbles were aligned with a preferred slip vector along the <111> directions. Focused ion beam profiles suggest that these bubbles nucleated as platelets at depths of 200 nm–1 μm beneath the surface and grew as a result of expansion of sub-surface cracks. Furthermore, to estimate the amount of deuterium trapped in these defects relative to other sites within the material, we applied a continuum-scale treatment of hydrogen isotope precipitation. Additionally, we propose a straightforward model of near-surface platelet expansion that reproduces bubble sizes consistent with our measurements. For the tungsten microstructure considered here, we find that bubbles would only weakly affect migration of D into the material, perhaps explaining why deep trapping was observed in prior studies with plasma-exposed neutron-irradiated specimens. We foresee no insurmountable issues that would prevent the theoretical framework developed here from being extended to a broader range of systems where precipitation of insoluble gases in ion beam or plasma-exposed metals is of interest.« less

Intermittency in flux driven kinetic simulations of trapped ion turbulence

NASA Astrophysics Data System (ADS)

Darmet, G.; Ghendrih, Ph.; Sarazin, Y.; Garbet, X.; Grandgirard, V.

2008-02-01

Flux driven kinetic transport is analysed for deeply trapped ion turbulence with the code GYSELA. The main observation is the existence of a steady state situation with respect to the statistics, in particular the balance between the injected energy and the time averaged energy flowing out through the outer edge boundary layer. The temperature is characterised by a very bursty behaviour with a skewed PDF. Superimposed to these short time scale fluctuations, one finds a regime with a strong increase of the zonal flows and a quenching of the turbulent energy. During this phase of such a predator-prey cycle, the core temperature rapidly increases while the edge temperature gradually decreases. The end of this reduced transport regime is governed by the onset of turbulence that governs large relaxation events, and a strong modification of the zonal flow pattern.

Fabrication of the replica templated from butterfly wing scales with complex light trapping structures

NASA Astrophysics Data System (ADS)

Han, Zhiwu; Li, Bo; Mu, Zhengzhi; Yang, Meng; Niu, Shichao; Zhang, Junqiu; Ren, Luquan

2015-11-01

The polydimethylsiloxane (PDMS) positive replica templated twice from the excellent light trapping surface of butterfly Trogonoptera brookiana wing scales was fabricated by a simple and promising route. The exact SiO2 negative replica was fabricated by using a synthesis method combining a sol-gel process and subsequent selective etching. Afterwards, a vacuum-aided process was introduced to make PDMS gel fill into the SiO2 negative replica, and the PDMS gel was solidified in an oven. Then, the SiO2 negative replica was used as secondary template and the structures in its surface was transcribed onto the surface of PDMS. At last, the PDMS positive replica was obtained. After comparing the PDMS positive replica and the original bio-template in terms of morphology, dimensions and reflectance spectra and so on, it is evident that the excellent light trapping structures of butterfly wing scales were inherited by the PDMS positive replica faithfully. This bio-inspired route could facilitate the preparation of complex light trapping nanostructure surfaces without any assistance from other power-wasting and expensive nanofabrication technologies.

Role of Clay Minerals in Long-Distance Transport of Landslides in Valles Marineris, Mars

NASA Astrophysics Data System (ADS)

Watkins, J.; Ehlmann, B. L.; Yin, A.

2014-12-01

Long-runout (> 50 km) subaerial landslides are rare on Earth, but are common features episodically shaping Mars' Valles Marineris (VM) trough system over the past 3.5 billion years. They display two end-member morphologies: a thick-skinned inner zone, characterized by fault-bounded, rotated blocks near their source region, and a thin-skinned, exceptionally long-runout outer zone, characterized by thin sheets spreading over 10s of km across the trough floor. Four decades of studies on the latter have resulted in two main competing hypotheses to explain their long-distance transport: (1) movement of landslides over layers of trapped air or soft materials containing ice or snow, enabling basal lubrication, and (2) fluidization of landslide materials with or without the presence of water and volatiles. To address this issue, we examine the mineralogic composition of landslides across VM using Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) near-infrared spectral data analysis coupled with detailed geologic mapping and morphometric analysis of satellite images. Our survey reveals a general correlation between transport distance, significant lateral spreading, and the presence of hydrated silicates among VM landslides. Given that smectite clay absorbs water into its layered crystal structure and can reduce the friction coefficient by a factor of three v. that of dry rocks, these results suggest that hydrated silicates played a decisive role in facilitating long-runout landslide transport in VM. We propose that, concurrent with downslope failure and sliding of broken trough-wall rock, frontal landslide masses overrode and entrained hydrated-silicate-bearing trough-floor deposits, lubricating the basal sliding zones and permitting the landslide outer zones to spread laterally while moving forward over the low-friction surface. The key participation of hydrated silicates in episodic, sustained landslide activity throughout the canyon implies that clay minerals, generated by water-rock interactions in the Noachian and Hesperian (4.1- 3.3 Ga), exert a long-lasting influence on geomorphic processes that shape the surface of the planet.

Helium gas bubble trapped in liquid helium in high magnetic field

NASA Astrophysics Data System (ADS)

Bai, H.; Hannahs, S. T.; Markiewicz, W. D.; Weijers, H. W.

2014-03-01

High magnetic field magnets are used widely in the area of the condensed matter physics, material science, chemistry, geochemistry, and biology at the National High Magnetic Field Laboratory. New high field magnets of state-of-the-art are being pursued and developed at the lab, such as the current developing 32 T, 32 mm bore fully superconducting magnet. Liquid Helium (LHe) is used as the coolant for superconducting magnets or samples tested in a high magnetic field. When the magnetic field reaches a relatively high value the boil-off helium gas bubble generated by heat losses in the cryostat can be trapped in the LHe bath in the region where BzdBz/dz is less than negative 2100 T2/m, instead of floating up to the top of LHe. Then the magnet or sample in the trapped bubble region may lose efficient cooling. In the development of the 32 T magnet, a prototype Yttrium Barium Copper Oxide coil of 6 double pancakes with an inner diameter of 40 mm and an outer diameter of 140 mm was fabricated and tested in a resistive magnet providing a background field of 15 T. The trapped gas bubble was observed in the tests when the prototype coil was ramped up to 7.5 T at a current of 200 A. This letter reports the test results on the trapped gas bubble and the comparison with the analytical results which shows they are in a good agreement.

Surface flashover performance of epoxy resin microcomposites improved by electron beam irradiation

NASA Astrophysics Data System (ADS)

Huang, Yin; Min, Daomin; Li, Shengtao; Li, Zhen; Xie, Dongri; Wang, Xuan; Lin, Shengjun

2017-06-01

The influencing mechanism of electron beam irradiation on surface flashover of epoxy resin/Al2O3 microcomposite was investigated. Epoxy resin/Al2O3 microcomposite samples with a diameter of 50 mm and a thickness of 1 mm were prepared. The samples were irradiated by electron beam with energies of 10 and 20 keV and a beam current of 5 μA for 5 min. Surface potential decay, surface conduction, and surface flashover properties of untreated and irradiated samples were measured. Both the decay rate of surface potential and surface conductivity decrease with an increase in the energy of electron beam. Meanwhile, surface flashover voltage increase. It was found that both the untreated and irradiated samples have two trap centers, which are labeled as shallow and deep traps. The increase in the energy and density of deep surface traps enhance the ability to capture primary emitted electrons. In addition, the decrease in surface conductivity blocks electron emission at the cathode triple junction. Therefore, electron avalanche at the interface between gas and an insulating material would be suppressed, eventually improving surface flashover voltage of epoxy resin microcomposites.

Method of fabricating a prestressed cast iron vessel

DOEpatents

Lampe, Robert F.

1982-01-01

A method of fabricating a prestressed cast iron vessel wherein double wall cast iron body segments each have an arcuate inner wall and a spaced apart substantially parallel outer wall with a plurality of radially extending webs interconnecting the inner wall and the outer wall, the bottom surface and the two exposed radial side surfaces of each body segment are machined and eight body segments are formed into a ring. The top surfaces and outer surfaces of the outer walls are machined and keyways are provided across the juncture of adjacent end walls of the body segments. A liner segment complementary in shape to a selected inner wall of one of the body segments is mounted to each of the body segments and again formed into a ring. The liner segments of each ring are welded to form unitary liner rings and thereafter the cast iron body segments are prestressed to complete the ring assembly. Ring assemblies are stacked to form the vessel and adjacent unitary liner rings are welded. A top head covers the top ring assembly to close the vessel and axially extending tendons retain the top and bottom heads in place under pressure.

ALMA unveils rings and gaps in the protoplanetary system HD 169142: signatures of two giant protoplanets

NASA Astrophysics Data System (ADS)

Fedele, D.; Carney, M.; Hogerheijde, M. R.; Walsh, C.; Miotello, A.; Klaassen, P.; Bruderer, S.; Henning, Th.; van Dishoeck, E. F.

2017-04-01

The protoplanetary system HD 169142 is one of the few cases where a potential candidate protoplanet has recently been detected by direct imaging in the near-infrared. To study the interaction between the protoplanet and the disk itself, observations of the gas and dust surface density structure are needed. This paper reports new ALMA observations of the dust continuum at 1.3 mm, 12CO, 13CO, and C18O J = 2-1 emission from the system HD 169142 (which is observed almost face-on) at an angular resolution of 0.3 arcsec × 0.2 arcsec ( 35 × 20 au). The dust continuum emission reveals a double-ring structure with an inner ring between 0.17 arcsec{-0.28 arcsec} ( 20-35 au) and an outer ring between 0.48 arcsec{-0.64 arcsec} ( 56-83 au). The size and position of the inner ring is in good agreement with previous polarimetric observations in the near-infrared and is consistent with dust trapping by a massive planet. No dust emission is detected inside the inner dust cavity (R ≲ 20 au) or within the dust gap ( 35-56 au) down to the noise level. In contrast, the channel maps of the J = 2-1 line of the three CO isotopologs reveal gas inside the dust cavity and dust gap. The gaseous disk is also much larger than the compact dust emission; it extends to 1.5 arcsec ( 180 au) in radius. This difference and the sharp drop of the continuum emission at large radii point to radial drift of large dust grains (>μm size). Using the thermo-chemical disk code dali, we modeled the continuum and the CO isotopolog emission to quantitatively measure the gas and dust surface densities. The resulting gas surface density is reduced by a factor of 30-40 inward of the dust gap. The gas and dust distribution indicate that two giant planets shape the disk structure through dynamical clearing (dust cavity and gap) and dust trapping (double-ring dust distribution).

Raman spectra and optical trapping of highly refractive and nontransparent particles

NASA Astrophysics Data System (ADS)

Xie, Changan; Li, Yong-qing

2002-08-01

We measured the Raman spectra of single optically trapped highly refractive and nontransparent microscopic particles suspended in a liquid using an inverted confocal laser-tweezers-Raman-spectroscopy system. A low-power diode-laser beam of TEM00 mode was used both for optical trapping and Raman excitation of refractive, absorptive, and reflective metal particles. To form a stable trap for a nontransparent particle, the beam focus was located near the top of the particle and the particle was pushed against a glass plate by the axial repulsive force. Raman spectra from single micron-sized crystals with high index of refraction including silicon, germanium, and KNbO3, and from absorptive particles of black and color paints were recorded. Surface-enhanced Raman scattering of R6G and phenylalanine molecules absorbed on the surface of a trapped cluster of silver particles was also demonstrated.

Ceramic molar crown reproducibility by digital workflow manufacturing: An in vitro study.

PubMed

Jeong, Ii-Do; Kim, Woong-Chul; Park, Jinyoung; Kim, Chong-Myeong; Kim, Ji-Hwan

2017-08-01

This in vitro study aimed to analyze and compare the reproducibility of zirconia and lithium disilicate crowns manufactured by digital workflow. A typodont model with a prepped upper first molar was set in a phantom head, and a digital impression was obtained with a video intraoral scanner (CEREC Omnicam; Sirona GmbH), from which a single crown was designed and manufactured with CAD/CAM into a zirconia crown and lithium disilicate crown (n=12). Reproducibility of each crown was quantitatively retrieved by superimposing the digitized data of the crown in 3D inspection software, and differences were graphically mapped in color. Areas with large differences were analyzed with digital microscopy. Mean quadratic deviations (RMS) quantitatively obtained from each ceramic group were statistically analyzed with Student's t-test (α=.05). The RMS value of lithium disilicate crown was 29.2 (4.1) µm and 17.6 (5.5) µm on the outer and inner surfaces, respectively, whereas these values were 18.6 (2.0) µm and 20.6 (5.1) µm for the zirconia crown. Reproducibility of zirconia and lithium disilicate crowns had a statistically significant difference only on the outer surface ( P <.001). The outer surface of lithium disilicate crown showed over-contouring on the buccal surface and under-contouring on the inner occlusal surface. The outer surface of zirconia crown showed both over- and under-contouring on the buccal surface, and the inner surface showed under-contouring in the marginal areas. Restoration manufacturing by digital workflow will enhance the reproducibility of zirconia single crowns more than that of lithium disilicate single crowns.

Anchorless surface associated glycolytic enzymes from Lactobacillus plantarum 299v bind to epithelial cells and extracellular matrix proteins.

PubMed

Glenting, Jacob; Beck, Hans Christian; Vrang, Astrid; Riemann, Holger; Ravn, Peter; Hansen, Anne Maria; Antonsson, Martin; Ahrné, Siv; Israelsen, Hans; Madsen, Søren

2013-06-12

An important criterion for the selection of a probiotic bacterial strain is its ability to adhere to the mucosal surface. Adhesion is usually mediated by proteins or other components located on the outer cell surface of the bacterium. In the present study we characterized the adhesive properties of two classical intracellular enzymes glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and enolase (ENO) isolated from the outer cell surface of the probiotic bacterium Lactobacillus plantarum 299v. None of the genes encoded signal peptides or cell surface anchoring motifs that could explain their extracellular location on the bacterial surface. The presence of the glycolytic enzymes on the outer surface was verified by western blotting using polyclonal antibodies raised against the specific enzymes. GAPDH and ENO showed a highly specific binding to plasminogen and fibronectin whereas GAPDH but not ENO showed weak binding to mucin. Furthermore, a pH dependent and specific binding of GAPDH and ENO to intestinal epithelial Caco-2 cells at pH 5 but not at pH 7 was demonstrated. The results showed that these glycolytic enzymes could play a role in the adhesion of the probiotic bacterium L. plantarum 299v to the gastrointestinal tract of the host. Finally, a number of probiotic as well non-probiotic Lactobacillus strains were analyzed for the presence of GAPDH and ENO on the outer surface, but no correlation between the extracellular location of these enzymes and the probiotic status of the applied strains was demonstrated. Copyright © 2013 Elsevier GmbH. All rights reserved.

Outer brain barriers in rat and human development

PubMed Central

Brøchner, Christian B.; Holst, Camilla B.; Møllgård, Kjeld

2015-01-01

Complex barriers at the brain's surface, particularly in development, are poorly defined. In the adult, arachnoid blood-cerebrospinal fluid (CSF) barrier separates the fenestrated dural vessels from the CSF by means of a cell layer joined by tight junctions. Outer CSF-brain barrier provides diffusion restriction between brain and subarachnoid CSF through an initial radial glial end feet layer covered with a pial surface layer. To further characterize these interfaces we examined embryonic rat brains from E10 to P0 and forebrains from human embryos and fetuses (6–21st weeks post-conception) and adults using immunohistochemistry and confocal microscopy. Antibodies against claudin-11, BLBP, collagen 1, SSEA-4, MAP2, YKL-40, and its receptor IL-13Rα2 and EAAT1 were used to describe morphological characteristics and functional aspects of the outer brain barriers. Claudin-11 was a reliable marker of the arachnoid blood-CSF barrier. Collagen 1 delineated the subarachnoid space and stained pial surface layer. BLBP defined radial glial end feet layer and SSEA-4 and YKL-40 were present in both leptomeningeal cells and end feet layer, which transformed into glial limitans. IL-13Rα2 and EAAT1 were present in the end feet layer illustrating transporter/receptor presence in the outer CSF-brain barrier. MAP2 immunostaining in adult brain outlined the lower border of glia limitans; remnants of end feet were YKL-40 positive in some areas. We propose that outer brain barriers are composed of at least 3 interfaces: blood-CSF barrier across arachnoid barrier cell layer, blood-CSF barrier across pial microvessels, and outer CSF-brain barrier comprising glial end feet layer/pial surface layer. PMID:25852456

Outer brain barriers in rat and human development.

PubMed

Brøchner, Christian B; Holst, Camilla B; Møllgård, Kjeld

2015-01-01

Complex barriers at the brain's surface, particularly in development, are poorly defined. In the adult, arachnoid blood-cerebrospinal fluid (CSF) barrier separates the fenestrated dural vessels from the CSF by means of a cell layer joined by tight junctions. Outer CSF-brain barrier provides diffusion restriction between brain and subarachnoid CSF through an initial radial glial end feet layer covered with a pial surface layer. To further characterize these interfaces we examined embryonic rat brains from E10 to P0 and forebrains from human embryos and fetuses (6-21st weeks post-conception) and adults using immunohistochemistry and confocal microscopy. Antibodies against claudin-11, BLBP, collagen 1, SSEA-4, MAP2, YKL-40, and its receptor IL-13Rα2 and EAAT1 were used to describe morphological characteristics and functional aspects of the outer brain barriers. Claudin-11 was a reliable marker of the arachnoid blood-CSF barrier. Collagen 1 delineated the subarachnoid space and stained pial surface layer. BLBP defined radial glial end feet layer and SSEA-4 and YKL-40 were present in both leptomeningeal cells and end feet layer, which transformed into glial limitans. IL-13Rα2 and EAAT1 were present in the end feet layer illustrating transporter/receptor presence in the outer CSF-brain barrier. MAP2 immunostaining in adult brain outlined the lower border of glia limitans; remnants of end feet were YKL-40 positive in some areas. We propose that outer brain barriers are composed of at least 3 interfaces: blood-CSF barrier across arachnoid barrier cell layer, blood-CSF barrier across pial microvessels, and outer CSF-brain barrier comprising glial end feet layer/pial surface layer.

Abrasion Testing of Candidate Outer Layer Fabrics for Lunar EVA Space Suits

NASA Technical Reports Server (NTRS)

Mitchell, Kathryn

2009-01-01

During the Apollo program, the space suit outer layer fabrics were severely abraded after just a few Extravehicular Activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots, which penetrated the outer layer fabric into the thermal protection layers after less than eight hours of surface operations. Current plans for the Constellation Space Suit Element require the space suits to support hundreds of hours of EVA on the Lunar surface, creating a challenge for space suit designers to utilize materials advances made over the last forty years and improve upon the space suit fabrics used in the Apollo program. A test methodology has been developed by the NASA Johnson Space Center Crew and Thermal Systems Division for establishing comparative abrasion wear characteristics between various candidate space suit outer layer fabrics. The abrasion test method incorporates a large rotary drum tumbler with rocks and loose lunar simulant material to induce abrasion in fabric test cylinder elements, representative of what might occur during long term planetary surface EVAs. Preliminary materials screening activities were conducted to determine the degree of wear on representative space suit outer layer materials and the corresponding dust permeation encountered between subsequent sub-layers of thermal protective materials when exposed to a simulated worst case eight hour EVA. The test method was used to provide a preliminary evaluation of four candidate outer layer fabrics for future planetary surface space suit applications. This paper provides a review of previous abrasion studies on space suit fabrics, details the methodologies used for abrasion testing in this particular study, shares the results of the testing, and provides recommendations for future work.

Abrasion Testing of Candidate Outer Layer Fabrics for Lunar EVA Space Suits

NASA Technical Reports Server (NTRS)

Mitchell, Kathryn C.

2010-01-01

During the Apollo program, the space suit outer layer fabrics were badly abraded after just a few Extravehicular Activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots, which penetrated the outer layer fabric into the thermal protection layers after less than eight hours of surface operations. Current plans for the Constellation Space Suit Element require the space suits to support hundreds of hours of EVA on the Lunar surface, creating a challenge for space suit designers to utilize materials advances made over the last forty years and improve upon the space suit fabrics used in the Apollo program. A test methodology has been developed by the NASA Johnson Space Center Crew and Thermal Systems Division for establishing comparative abrasion wear characteristics between various candidate space suit outer layer fabrics. The abrasion test method incorporates a large rotary drum tumbler with rocks and loose lunar simulant material to induce abrasion in fabric test cylinder elements, representative of what might occur during long term planetary surface EVAs. Preliminary materials screening activities were conducted to determine the degree of wear on representative space suit outer layer materials and the corresponding dust permeation encountered between subsequent sub -layers of thermal protective materials when exposed to a simulated worst case eight hour EVA. The test method was used to provide a preliminary evaluation of four candidate outer layer fabrics for future planetary surface space suit applications. This Paper provides a review of previous abrasion studies on space suit fabrics, details the methodologies used for abrasion testing in this particular study, and shares the results and conclusions of the testing.

Open cycle ocean thermal energy conversion system

DOEpatents

Wittig, J. Michael

1980-01-01

An improved open cycle ocean thermal energy conversion system including a flash evaporator for vaporizing relatively warm ocean surface water and an axial flow, elastic fluid turbine having a vertical shaft and axis of rotation. The warm ocean water is transmitted to the evaporator through a first prestressed concrete skirt-conduit structure circumferentially situated about the axis of rotation. The unflashed warm ocean water exits the evaporator through a second prestressed concrete skirt-conduit structure located circumferentially about and radially within the first skirt-conduit structure. The radially inner surface of the second skirt conduit structure constitutes a cylinder which functions as the turbine's outer casing and obviates the need for a conventional outer housing. The turbine includes a radially enlarged disc element attached to the shaft for supporting at least one axial row of radially directed blades through which the steam is expanded. A prestressed concrete inner casing structure of the turbine has upstream and downstream portions respectively situated upstream and downstream from the disc element. The radially outer surfaces of the inner casing portions and radially outer periphery of the axially interposed disc cooperatively form a downwardly radially inwardly tapered surface. An annular steam flowpath of increasing flow area in the downward axial direction is radially bounded by the inner and outer prestressed concrete casing structures. The inner casing portions each include a transversely situated prestressed concrete circular wall for rotatably supporting the turbine shaft and associated structure. The turbine blades are substantially radially coextensive with the steam flowpath and receive steam from the evaporator through an annular array of prestressed concrete stationary vanes which extend between the inner and outer casings to provide structural support therefor and impart a desired flow direction to the steam.

Silica-forming articles having engineered surfaces to enhance resistance to creep sliding under high-temperature loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lipkin, Don Mark; Johnson, Curtis Alan; Meschter, Peter Joel

An article includes a silicon-containing region; at least one outer layer overlying a surface of the silicon-containing region; and a constituent layer on the surface of the silicon-containing region and between and contacting the silicon-containing region and the at least one outer layer, the constituent layer being formed by constituents of the silicon-containing region and being susceptible to creep within an operating environment of the article, wherein the silicon-containing region defines a plurality of channels and a plurality of ridges that interlock within the plurality of channels are formed in the silicon-containing region to physically interlock the at least onemore » outer layer with the silicon-containing region through the constituent layer.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Checco, A.; Hofmann, T.; DiMasi, E.

The details of air nanobubble trapping at the interface between water and a nanostructured hydrophobic silicon surface are investigated using X-ray scattering and contact angle measurements. Large-area silicon surfaces containing hexagonally packed, 20 nm wide hydrophobic cavities provide ideal model surfaces for studying the morphology of air nanobubbles trapped inside cavities and its dependence on the cavity depth. Transmission small-angle X-ray scattering measurements show stable trapping of air inside the cavities with a partial water penetration of 5-10 nm into the pores, independent of their large depth variation. This behavior is explained by consideration of capillary effects and the cavitymore » geometry. For parabolic cavities, the liquid can reach a thermodynamically stable configuration - a nearly planar nanobubble meniscus - by partially penetrating into the pores. This microscopic information correlates very well with the macroscopic surface wetting behavior.« less

Appendage mountable electronic devices conformable to surfaces

DOEpatents

Rogers, John; Ying, Ming; Bonifas, Andrew; Lu, Nanshu

2017-01-24

Disclosed are appendage mountable electronic systems and related methods for covering and conforming to an appendage surface. A flexible or stretchable substrate has an inner surface for receiving an appendage, including an appendage having a curved surface, and an opposed outer surface that is accessible to external surfaces. A stretchable or flexible electronic device is supported by the substrate inner and/or outer surface, depending on the application of interest. The electronic device in combination with the substrate provides a net bending stiffness to facilitate conformal contact between the inner surface and a surface of the appendage provided within the enclosure. In an aspect, the system is capable of surface flipping without adversely impacting electronic device functionality, such as electronic devices comprising arrays of sensors, actuators, or both sensors and actuators.

Quantum Information Experiments with Trapped Ions at NIST

NASA Astrophysics Data System (ADS)

Wilson, Andrew

2015-03-01

We present an overview of recent trapped-ion quantum information experiments at NIST. Advancing beyond few-qubit ``proof-of-principle'' experiments to the many-qubit systems needed for practical quantum simulation and information processing, without compromising on the performance demonstrated with small systems, remains a major challenge. One approach to scalable hardware development is surface-electrode traps. Micro-fabricated planar traps can have a number of useful features, including flexible electrode geometries, integrated microwave delivery, and spatio-temporal tuning of potentials for ion transport and spin-spin interactions. In this talk we report on a number of on-going investigations with surface traps. Experiments feature a multi-zone trap with closely spaced ions in a triangular arrangement (a first step towards 2D arrays of ions with tunable spin-spin interactions), a scheme for smooth transport through a junction in a 2D structure based on switchable RF potentials, and a micro-fabricated photo-detector integrated into a trap. We also give a progress report on our latest efforts to improve the fidelity of both optical and microwave 2-qubit gates. This work was supported by IARPA, ONR and the NIST Quantum Information Program. The 3-ion and switchable-RF-junction traps were developed in collaboration with Sandia National Laboratory.

Why Buckling Stellar Bars Weaken in Disk Galaxies

NASA Astrophysics Data System (ADS)

Martinez-Valpuesta, Inma; Shlosman, Isaac

2004-09-01

Young stellar bars in disk galaxies experience a vertical buckling instability that terminates their growth and thickens them, resulting in a characteristic peanut/boxy shape when viewed edge-on. Using N-body simulations of galactic disks embedded in live halos, we have analyzed the bar structure throughout this instability and found that the outer (approximately) third of the bar dissolves completely while the inner part (within the vertical inner Lindblad resonance) becomes less oval. The bar acquires the frequently observed peanut/boxy-shaped isophotes. We also find that the bar buckling is responsible for a mass injection above the plane, which is subsequently trapped by specific three-dimensional families of periodic orbits of particular shapes explaining the observed isophotes, in line with previous work. Using a three-dimensional orbit analysis and surfaces of sections, we infer that the outer part of the bar is dissolved by a rapidly widening stochastic region around its corotation radius-a process related to the bar growth. This leads to a dramatic decrease in the bar size, decrease in the overall bar strength, and a mild increase in its pattern speed but is not expected to lead to a complete bar dissolution. The buckling instability appears primarily responsible for shortening the secular diffusion timescale to a dynamical one when building the boxy isophotes. The sufficiently long timescale of the described evolution, ~1 Gyr, can affect the observed bar fraction in the local universe and at higher redshifts, both through reduced bar strength and the absence of dust offset lanes in the bar.

Unusual distribution of floating seaweeds in the East China Sea in the early spring of 2012.

PubMed

Komatsu, Teruhisa; Mizuno, Shizuha; Natheer, Alabsi; Kantachumpoo, Attachai; Tanaka, Kiyoshi; Morimoto, Akihiko; Hsiao, Sheng-Tai; Rothäusler, Eva A; Shishidou, Hirotoshi; Aoki, Masakazu; Ajisaka, Tetsuro

2014-01-01

Floating seaweeds play important ecological roles in offshore waters. Recently, large amounts of rafting seaweed have been observed in the East China Sea. In early spring, juveniles of commercially important fish such as yellowtail accompany these seaweed rafts. Because the spatial distributions of seaweed rafts in the spring are poorly understood, research cruises were undertaken to investigate them in 2010, 2011, and 2012. Floating seaweed samples collected from the East China Sea during the three surveys contained only Sargassum horneri . In 2010 and 2011, seaweed rafts were distributed only in the continental shelf and the Kuroshio Front because they had become trapped in the convergence zone of the Kuroshio Front. However, in 2012, seaweed was also distributed in the Kuroshio Current and its outer waters, and massive strandings of seaweed rafts were observed on the northern coast of Taiwan and on Tarama Island in the Ryukyu Archipelago. Environmental data (wind, currents, and sea surface height) were compared among the surveys of 2010, 2011, and 2012. Two factors are speculated to have caused the unusual distribution in 2012. First, a continuous strong north wind produced an Ekman drift current that transported seaweed southwestward to the continental shelf and eventually stranded seaweed rafts on the coast of Taiwan. Second, an anticyclonic eddy covering northeast Taiwan and the Kuroshio Current west of Taiwan generated a geostrophic current that crossed the Kuroshio Current and transported the rafts to the Kuroshio Current and its outer waters. Such unusual seaweed distributions may influence the distribution of fauna accompanying the rafts.

Playing with inclined circular hydraulic jumps

NASA Astrophysics Data System (ADS)

Lebon, Luc; Saget, Beryl; Durand, Marc; Limat, Laurent; Couder, Yves; Receveur, Mathieu

2008-11-01

We have investigated the structure of the circular hydraulic jump, when the jet impacts an inclined plate. At low plate slope, quasi-circular shapes, evolving towards elliptic shapes are observed. At moderate inclinations, the upper and lower jumps become markedly different, and the lower jump is even rejected to infinity when a critical inclination is reached. Above this critical inclination, the jump is coupled to an outer dewetting contact line to give a specific object (expanding impact sheet feeding a curved rim in which the liquid is flowing tangentially). In this regime, both the position and curvature of the upper jump follows unusual scalings with the flow rate that completely differ from those observed on horizontal plates. Finally we have looked to metastable drops trapped in the circular jump at very small inclinations. As reported in a previous APS, the lowest position in the jump can become unstable and the drops oscillate around the jump perimeter. We show that this behavior requires very specific conditions of surface tension and viscosity and propose simple interpretations for the instability mechanism.

Energetic particle signatures of satellites and rings in Neptune's magnetosphere

NASA Technical Reports Server (NTRS)

Selesnick, R. S.; Stone, E. C.

1992-01-01

The cosmic ray system on Voyager 2 found a trapped radiation environment in Neptune's inner magnetosphere which is controlled primarily by absorption at the rings and satellite surfaces. The intensity of electrons with kinetic energies approximately greater than 1 MeV shows particularly strong and narrow signatures associated with absorption by the satellite 1989N1 at an orbital radius of 4.75 Neptune radii. Closer to the planet are several signatures of the inner satellites and rings. Absorption limits the intensity of the inner radiation belt sufficiently for the maximum intensity to occur outside the orbit of 1989N1 at a magnetic L shell of about 7. Radial profiles of the electron phase space density show that electrons diffuse inward from a source in the outer magnetosphere. Many of the inward-diffusing electrons are absorbed upon reaching a satellite orbital radius, but the finite absorption efficiency allows some of the electrons to pass by unaffected. The locations of the satellite and ring signatures also provide constraints on the nondipolar components of the planetary magnetic field.

Space Science

NASA Image and Video Library

2002-06-01

NASA's Marshall Space Flight Center (MSFC) and university scientists from the National Space Science and Technology Center (NSSTC) in Huntsville, Alabama, are watching the Sun in an effort to better predict space weather - blasts of particles and magnetic fields from the Sun that impact the magnetosphere, the magnetic bubble around the Earth. Filled by charged particles trapped in the Earth's magnetic field, the spherical comet-shaped magnetosphere extends out 40,000 miles from Earth's surface in the sunward direction and more in other directions. This image illustrates the Sun-Earth cornection. When massive solar explosions, known as coronal mass ejections, blast through the Sun's outer atmosphere and plow toward Earth at speeds of thousands of miles per second, the resulting effects can be harmful to communication satellites and astronauts outside the Earth's magnetosphere. Like severe weather on Earth, severe space weather can be costly. On the ground, magnetic storms wrought by these solar particles can knock out electric power. By using the Solar Vector Magnetograph, a solar observation facility at MSFC, scientists are learning what signs to look for as indicators of potential severe space weather.

Measured responses of internal enclosures and cables due to burnthrough penetration of weapon cases by lightning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schnetzer, G.H.; Fisher, R.J.; Dinallo, M.A.

1994-08-01

The electrical effects of lightning penetration of the outer case of a weapon on internal structures, such as a firing set housing, and on samples of a flat, flexline detonator cable have been investigated experimentally. Maximum open-circuit voltages measured on either simulated structures (126 V) or the cable (46 V) located directly behind the point of penetration were well below any level that is foreseen to create a threat to nuclear safety. On the other hand, it was found that once full burnthrough of the barrier occurred, significant fractions of the incident continuing currents coupled to both the simulated internalmore » structure (up to 300 A) or to the cable sample (69 A) when each was electrically connected internally to case ground. No occurrence was observed of the injection of large amplitude currents from return strokes occurring after barrier penetration. Under circumstances in which small volumes of trapped gases exist behind penetration sites, rapid heating of the gas by return strokes occurring after burnthrough has been shown to produced large mechanical impulses to the adjacent surfaces.« less

Catalyst cartridge for carbon dioxide reduction unit

NASA Technical Reports Server (NTRS)

Holmes, R. F. (Inventor)

1973-01-01

A catalyst cartridge, for use in a carbon dioxide reducing apparatus in a life support system for space vehicles, is described. The catalyst cartridge includes an inner perforated metal wall, an outer perforated wall space outwardly from the inner wall, a base plate closing one end of the cartridge, and a cover plate closing the other end of the cartridge. The cover plate has a central aperture through which a supply line with a heater feeds a gaseous reaction mixture comprising hydrogen and carbon dioxide at a temperature from about 1000 to about 1400 F. The outer surfaces of the internal wall and the inner surfaces of the outer wall are lined with a ceramic fiber batting material of sufficient thickness to prevent carbon formed in the reaction from passing through it. The portion of the surfaces of the base and cover plates defined within the inner and outer walls are also lined with ceramic batting. The heated reaction mixture passes outwardly through the inner perforated wall and ceramic batting and over the catalyst. The solid carbon product formes is retained within the enclosure containing the catalyst. The solid carbon product formed is retained within the enclosure containing the catalyst. The water vapor and unreacted carbon dioxide and any intermediate products pass through the perforations of the outer wall.

Method for forming a liquid cooled airfoil for a gas turbine

DOEpatents

Grondahl, Clayton M.; Willmott, Leo C.; Muth, Myron C.

1981-01-01

A method for forming a liquid cooled airfoil for a gas turbine is disclosed. A plurality of holes are formed at spaced locations in an oversized airfoil blank. A pre-formed composite liquid coolant tube is bonded into each of the holes. The composite tube includes an inner member formed of an anti-corrosive material and an outer member formed of a material exhibiting a high degree of thermal conductivity. After the coolant tubes have been bonded to the airfoil blank, the airfoil blank is machined to a desired shape, such that a portion of the outer member of each of the composite tubes is contiguous with the outer surface of the machined airfoil blank. Finally, an external skin is bonded to the exposed outer surface of both the machined airfoil blank and the composite tubes.

Regional Sediment Management Strategies for the Vicinity of St. Augustine Inlet, St. Johns County, Florida

DTIC Science & Technology

2016-07-01

period 1941 to 1957 resulted in the construction of a north sand-trap groin structure approxi- mately 1,880 ft in length and a 3,695 ft long southern...jetty structure . The inlet channel and associated structures are maintained by SAJ. The project includes an outer channel authorized to -16 ft mean...erosion, several homes had to be temporarily vacated for major repairs, and several structures were granted permits to construct temporary sea walls

Microfabricated magnetic traps for single molecule manipulation and measurement

NASA Astrophysics Data System (ADS)

Mirowski, Elizabeth; Moreland, John; Russek, Stephen; Donahue, Michael

2003-03-01

We have microfabricated patterned magnetic thin film traps for capturing superparamagnetic beads in microfluidic cells. The traps are based on a novel concept of using a magnetic force microsope cantilever for transporting magnetic beads from one trap to another along the surface of a thin silicon nitride membrane. We specifically address the optimal design criteria for the traps. In addition, we present measurements of the forces on a bead (attached to a functionalized cantilever tip) as a function of its position near the trap. Equivalent spring constants of various trap geometries are extrapolated from the force measurements. The force measurements will be compared to micromagnetic modelling of the system as well as the Brownian motion of the bead in the trap.

Achieving Translationally Invariant Trapped Ion Rings

NASA Astrophysics Data System (ADS)

Urban, Erik; Li, Hao-Kun; Noel, Crystal; Hemmerling, Boerge; Zhang, Xiang; Haeffner, Hartmut

2017-04-01

We present the design and implementation of a novel surface ion trap design in a ring configuration. By eliminating the need for wire bonds through the use of electrical vias and using a rotationally invariant electrode configuration, we have realized a trap that is able to trap up to 20 ions in a ring geometry 45um in diameter, 400um above the trap surface. This large trapping height to ring diameter ratio allows for global addressing of the ring with both lasers and electric fields in the chamber, thereby increasing our ability to control the ring as a whole. Applying compensating electric fields, we measure very low tangential trap frequencies (less than 20kHz) corresponding to rotational barriers down to 4mK. This measurement is currently limited by the temperature of the ions but extrapolation indicates the barrier can be reduced much further with more advanced cooling techniques. Finally, we show that we are able to reduce this energy barrier sufficiently such that the ions are able to overcome it either through thermal motion or rotational motion and delocalize over the full extent of the ring. This work was funded by the Keck Foundation and the NSF.

Effect of annealing on the sub-bandgap, defects and trapping states of ZnO nanostructures

NASA Astrophysics Data System (ADS)

Wahyuono, Ruri Agung; Hermann-Westendorf, Felix; Dellith, Andrea; Schmidt, Christa; Dellith, Jan; Plentz, Jonathan; Schulz, Martin; Presselt, Martin; Seyring, Martin; Rettenmeyer, Markus; Dietzek, Benjamin

2017-02-01

Annealing treatment was applied to different mesoporous ZnO nanostructures prepared by wet chemical synthesis, i.e. nanoflowers (NFs), spherical aggregates (SPs), and nanorods (NRs). The sub-bandgap, defect properties as well as the trapping state characteristics after annealing were characterized spectroscopically, including ultrasensitive photothermal deflection spectroscopy (PDS), photoluminescence and photo-electrochemical methods. The comprehensive experimental analysis reveals that annealing alters both the bandgap and the sub-bandgap. The defect concentration and the density of surface traps in the ZnO nanostructures are suppressed upon annealing as deduced from photoluminescence and open-circuit voltage decay analysis. The photo-electrochemical investigations reveal that the surface traps dominate the near conduction band edge of ZnO and, hence, lead to high recombination rates when used in DSSCs. The density of bulk traps in ZnO SPs is higher than that in ZnO NFs and ZnO NRs and promote lower recombination loss between photoinjected electrons with the electrolyte-oxidized species on the surface. The highest power conversion efficiency of ZnO NFs-, ZnO SPs-, and ZnO NRs-based DSSC obtained in our system is 2.0, 4.5, and 1.8%, respectively.

Unified Electromagnetic-Electronic Design of Light Trapping Silicon Solar Cells

PubMed Central

Boroumand, Javaneh; Das, Sonali; Vázquez-Guardado, Abraham; Franklin, Daniel; Chanda, Debashis

2016-01-01

A three-dimensional unified electromagnetic-electronic model is developed in conjunction with a light trapping scheme in order to predict and maximize combined electron-photon harvesting in ultrathin crystalline silicon solar cells. The comparison between a bare and light trapping cell shows significant enhancement in photon absorption and electron collection. The model further demonstrates that in order to achieve high energy conversion efficiency, charge separation must be optimized through control of the doping profile and surface passivation. Despite having a larger number of surface defect states caused by the surface patterning in light trapping cells, we show that the higher charge carrier generation and collection in this design compensates the absorption and recombination losses and ultimately results in an increase in energy conversion efficiency. The fundamental physics behind this specific design approach is validated through its application to a 3 μm thick functional light trapping solar cell which shows 192% efficiency enhancement with respect to the bare cell of same thickness. Such a unified design approach will pave the path towards achieving the well-known Shockley-Queisser (SQ) limit for c-Si in thin-film (<30 μm) geometries. PMID:27499446

Sorption specificity and desorption hysteresis of gibberellic acid on ferrihydrite compared to goethite, hematite, montmorillonite, and kaolinite.

PubMed

Zhang, Li; Liu, Fei; Chen, Liang

2017-08-01

The pesticide gibberellic acid (GA 3 ) is a potential endocrine disruptor and environmental toxin; therefore, research into its environmental fate is warranted. Batch studies were conducted to investigate the sorption and desorption characteristics of GA 3 on aquifer media. The results demonstrated special sorption characteristic of GA 3 on ferrihydrite compared to goethite, hematite, montmorillonite, and kaolinite, where the sorption kinetics of GA 3 on ferrihydrite was fitted well with the pseudo-second-order, Elovich, and intra-particle diffusion models. The sorption kinetics of GA 3 on ferrihydrite indicated an initial high sorption rate followed by a slow reaction process. The initial high GA 3 sorption rate may be related to electrostatic sorption and surface complexation reactions on the outer surfaces and at the macropore entrances of ferrihydrite. While the slow step was controlled by GA 3 diffusion into mesopore of ferrihydrite. Analysis of the desorption hysteresis indicated a high hysteresis index (HI) ranging from 0.68 to 17.32, and a low desorption percentage ranging from 18 to 48%. After sufficient desorption, the calculated maximum residual GA 3 quantity due to surface complexation reactions with the ferrihydrite coordinated unsaturated sites was 9.05 ± 0.12 mg g -1 . The calculated maximum quantity of GA 3 trapped within the mesopore was 16.23 ± 0.91 mg g -1 . Graphical Abstract Schematic overview of GA 3 sorption and desorption on five minerals in groundwater.

Modelling deuterium release from tungsten after high flux high temperature deuterium plasma exposure

NASA Astrophysics Data System (ADS)

Grigorev, Petr; Matveev, Dmitry; Bakaeva, Anastasiia; Terentyev, Dmitry; Zhurkin, Evgeny E.; Van Oost, Guido; Noterdaeme, Jean-Marie

2016-12-01

Tungsten is a primary candidate for plasma facing materials for future fusion devices. An important safety concern in the design of plasma facing components is the retention of hydrogen isotopes. Available experimental data is vast and scattered, and a consistent physical model of retention of hydrogen isotopes in tungsten is still missing. In this work we propose a model of non-equilibrium hydrogen isotopes trapping under fusion relevant plasma exposure conditions. The model is coupled to a diffusion-trapping simulation tool and is used to interpret recent experiments involving high plasma flux exposures. From the computational analysis performed, it is concluded that high flux high temperature exposures (T = 1000 K, flux = 1024 D/m2/s and fluence of 1026 D/m2) result in generation of sub-surface damage and bulk diffusion, so that the retention is driven by both sub-surface plasma-induced defects (bubbles) and trapping at natural defects. On the basis of the non-equilibrium trapping model we have estimated the amount of H stored in the sub-surface region to be ∼10-5 at-1, while the bulk retention is about 4 × 10-7 at-1, calculated by assuming the sub-surface layer thickness of about 10 μm and adjusting the trap concentration to comply with the experimental results for the integral retention.

Multi-modality nanoparticles having optically responsive shape

DOEpatents

Chen, Fanqing; Bouchard, Louis-Serge

2015-05-19

In certain embodiments novel nanoparticles (nanowontons) are provided that are suitable for multimodal imaging and/or therapy. In one embodiment, the nanoparticles include a first biocompatible (e.g., gold) layer, an inner core layer (e.g., a non-biocompatible material), and a biocompatible (e.g., gold) layer. The first gold layer includes a concave surface that forms a first outer surface of the layered nanoparticle. The second gold layer includes a convex surface that forms a second outer surface of the layered nanoparticle. The first and second gold layers encapsulate the inner core material layer. Methods of fabricating such nanoparticles are also provided.

Effect of interstitial impurities on the field dependent microwave surface resistance of niobium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinello, M.; Grassellino, A.; Checchin, M.

Previous work has demonstrated that the radio frequency surface resistance of niobium resonators is dramatically reduced when nitrogen impurities are dissolved as interstitial in the material. The origin of this effect is attributed to the lowering of the Mattis and Bardeen surface resistance contribution with increasing accelerating field. Meanwhile, an enhancement of the sensitivity to trapped magnetic field is typically observed for such cavities. In this paper we conduct the first systematic study on these different components contributing to the total surface resistance as a function of different levels of dissolved nitrogen, in comparison with standard surface treatments for niobiummore » resonators. Adding these results together we are able to show for the first time which is the optimum surface treatment that maximizes the Q-factor of superconducting niobium resonators as a function of expected trapped magnetic field in the cavity walls. Lastly, these results also provide new insights on the physics behind the change in the field dependence of the Mattis and Bardeen surface resistance, and of the trapped magnetic vortex induced losses in superconducting niobium resonators.« less

Effect of interstitial impurities on the field dependent microwave surface resistance of niobium

DOE PAGES

Martinello, M.; Grassellino, A.; Checchin, M.; ...

2016-08-09

Previous work has demonstrated that the radio frequency surface resistance of niobium resonators is dramatically reduced when nitrogen impurities are dissolved as interstitial in the material. The origin of this effect is attributed to the lowering of the Mattis and Bardeen surface resistance contribution with increasing accelerating field. Meanwhile, an enhancement of the sensitivity to trapped magnetic field is typically observed for such cavities. In this paper we conduct the first systematic study on these different components contributing to the total surface resistance as a function of different levels of dissolved nitrogen, in comparison with standard surface treatments for niobiummore » resonators. Adding these results together we are able to show for the first time which is the optimum surface treatment that maximizes the Q-factor of superconducting niobium resonators as a function of expected trapped magnetic field in the cavity walls. Lastly, these results also provide new insights on the physics behind the change in the field dependence of the Mattis and Bardeen surface resistance, and of the trapped magnetic vortex induced losses in superconducting niobium resonators.« less

Trapping of vesicles on patterned surfaces by physisorption for potential biosensing applications.

PubMed

Bera, L K; Ong, Kian Soo; Wong, Zheng Zheng; Fu, Zhikang; Nallani, Madhavan; Shea, Sean O'

2012-01-01

The pre-defined selective positioning of a controlled number of vesicles on a rigid substrate is crucial in many potential applications such as diagnostics, biosensors, lab-on-a chip, microanalyses and reaction chambers. In this paper, the vesicles made up of block copolymer using Poly [-(2-methyloxazoline) -poly- (dimethylsiloxane)-poly- (2-methyloxazoline)] (ABA) with dimensions of 100-200 nm are trapped by physisorption on hydrophilic surfaces. We discuss the protocols established for vesicle trapping. The optimum conditions obtained for physisorption is 15 minutes incubation followed by one cycle of DI water rinse. Trapping of 1-10 vesicles in lobe shape micro-wells fabricated by photo lithography using photoresist on UltraStick(™) slides was demonstrated. To overcome the issue of amalgamation of emitted light from optically sensitive photoresist and fluorescently tagged vesicles, an alternative approach of Si/SiO(2) microwell array coupled with APTES (3-AminoPropylTriEthoxySilane) treated bottom surfaces was developed.

A surface-associated activity trap for capturing water surface and aquatic invertebrates in wetlands

USGS Publications Warehouse

Hanson, Mark A.; Roy, Christiane C.; Euliss, Ned H.; Zimmer, Kyle D.; Riggs, Michael R.; Butler, Malcolm G.

2000-01-01

We developed a surface-associated activity trap (SAT) for sampling aquatic invertebrates in wetlands. We compared performance of this trap with that of a conventional activity trap (AT) based on non-detection rates and relative abundance estimates for 13 taxa of common wetland invertebrates and for taxon richness using data from experiments in constructed wetlands. Taxon-specific non-detection rates for ATs generally exceeded those of SATs, and largest improvements using SATs were for Chironomidae and Gastropoda. SATs were efficient at capturing cladocera, Chironomidae, Gastropoda, total Crustacea, and multiple taxa (taxon richness) but were only slightly better than ATs at capturing Dytiscidae. Temporal differences in capture rates were observed only for cladocera, Chironomidae, Dytiscidae, and total Crustacea, with capture efficiencies of SATs usually decreasing from mid-June through mid-July for these taxa. We believe that SATs may be useful for characterizing wetland invertebrate communities and for developing improved measures of prey available to foraging waterfowl and other aquatic birds.

A surface-associated activity trap for capturing water-surface and aquatic invertebrates in wetlands

USGS Publications Warehouse

Hanson, M.A.; Roy, C.C.; Euliss, N.H.; Zimmer, K.D.; Riggs, M.R.; Butler, Malcolm G.

2000-01-01

We developed a surface-associated activity trap (SAT) for sampling aquatic invertebrates in wetlands. We compared performance of this trap with that of a conventional activity trap (AT) based on non-detection rates and relative abundance estimates for 13 taxa of common wetland invertebrates and for taxon richness using data from experiments in constructed wetlands. Taxon-specific non-detection rates for ATs generally exceeded those of SATs, and largest improvements using SATs were for Chironomidae and Gastropoda. SATs were efficient at capturing cladocera, Chironomidae, Gastropoda, total Crustacea, and multiple taxa (taxon richness) but were only slightly better than ATs at capturing Dytiscidae. Temporal differences in capture rates were observed only for cladocera, Chironomidae, Dytiscidae, and total Crustacea, with capture efficiencies of SATs usually decreasing from mid-June through mid-July for these taxa. We believe that SATs may be useful for characterizing wetland invertebrate communities and for developing improved measures of prey available to foraging waterfowl and other aquatic birds.

A Surface-Coupled Optical Trap with 1-bp Precision via Active Stabilization

PubMed Central

Okoniewski, Stephen R.; Carter, Ashley R.; Perkins, Thomas T.

2017-01-01

Optical traps can measure bead motions with Å-scale precision. However, using this level of precision to infer 1-bp motion of molecular motors along DNA is difficult, since a variety of noise sources degrade instrumental stability. In this chapter, we detail how to improve instrumental stability by (i) minimizing laser pointing, mode, polarization, and intensity noise using an acousto-optical-modulator mediated feedback loop and (ii) minimizing sample motion relative to the optical trap using a 3-axis piezo-electric-stage mediated feedback loop. These active techniques play a critical role in achieving a surface stability of 1 Å in 3D over tens of seconds and a 1-bp stability and precision in a surface-coupled optical trap over a broad bandwidth (Δf = 0.03–2 Hz) at low force (6 pN). These active stabilization techniques can also aid other biophysical assays that would benefit from improved laser stability and/or Å-scale sample stability, such as atomic force microscopy and super-resolution imaging. PMID:27844426

Propulsion and trapping of microparticles by active cilia arrays.

PubMed

Bhattacharya, Amitabh; Buxton, Gavin A; Usta, O Berk; Balazs, Anna C

2012-02-14

We model the transport of a microscopic particle via a regular array of beating elastic cilia, whose tips experience an adhesive interaction with the particle's surface. At optimal adhesion strength, the average particle velocity is maximized. Using simulations spanning a range of cilia stiffness and cilia-particle adhesion strength, we explore the parameter space over which the particle can be "released", "propelled", or "trapped" by the cilia. We use a lower-order model to predict parameters for which the cilia are able to "propel" the particle. This is the first study that shows how both stiffness and adhesion strength are crucial for manipulation of particles by active cilia arrays. These results can facilitate the design of synthetic cilia that integrate adhesive and hydrodynamic interactions to selectively repel or trap particulates. Surfaces that are effective at repelling particulates are valuable for antifouling applications, while surfaces that can trap and, thus, remove particulates from the solution are useful for efficient filtration systems.

Slow positrons in single-crystal samples of Al and Al-AlxOy

NASA Astrophysics Data System (ADS)

Lynn, K. G.; Lutz, H.

1980-11-01

Well-characterized Al(111) and Al(100) samples were studied with monoenergetic positrons before and after exposure to oxygen. Both positronium-formation and positron-emission curves were obtained for various incident positron energies at sample temperatures ranging from 160-900 K. The orthopositronium decay signal provides a unique signature that the positron has emerged from the surface region of a clean metal. In the clean Al crystals part of the positronium formed near the surface is found to be associated with a temperature-activated process described as the thermally activated detrapping of a positron from a surface state. A simple positron diffusion model, including surface and vacancy trapping, is fitted to the positronium data and an estimate of the binding energy of the positron in this trap is made. The positron diffusion constant is found to have a negative temperature dependence before the onset of positron trapping at thermally generated monovacancies (>500 K), in reasonable agreement with theoretical predictions. The depth of the positron surface state is reduced or positronium is formed in the chemisorbed layer as oxygen is adsorbed on both Al sample surfaces, thus increasing the positronium fraction and decreasing the positron emission. At higher oxygen exposures [>500 L (1 L = 10-6 torr sec)] positron or positronium traps are generated in the overlayer and the positronium fraction is reduced. The amorphous-to-crystalline surface transition of AlxOy on Al is observed between 650 and 800 K by the change in the positronium fraction and is interpreted as the removal of trapping centers in the metal-oxide overlayer. At the higher temperatures and incident energies vacancy trapping is observed by the decrease in the positron diffusion length in both the clean and the underlying Al of the oxygen-exposed samples. Similar vacancy formation enthalpies for Al are extracted in both the clean and oxygen-covered samples by a simple model and are in good agreement with those measured by other experimental methods. This technique provides a new experimental means for the study of interfaces and thin films and the vacancy-type defects associated with them.

Effects of surface and interface traps on exciton and multi-exciton dynamics in core/shell quantum dots

NASA Astrophysics Data System (ADS)

Bozio, Renato; Righetto, Marcello; Minotto, Alessandro

2017-08-01

Exciton interactions and dynamics are the most important factors determining the exceptional photophysical properties of semiconductor quantum dots (QDs). In particular, best performances have been obtained for ingeniously engineered core/shell QDs. We have studied two factors entering in the exciton decay dynamics with adverse effects for the luminescence efficiency: exciton trapping at surface and interface traps, and non-radiative Auger recombination in QDs carrying either net charges or multiple excitons. In this work, we present a detailed study into the optical absorption, fluorescence dynamics and quantum yield, as well as ultrafast transient absorption properties of CdSe/CdS, CdSe/Cd0.5Zn0.5S, and CdSe/ZnS QDs as a function of shell thickness. It turns out that de-trapping processes play a pivotal role in determining steady state emission properties. By studying the excitation dependent photoluminescence quantum yields (PLQY) in different CdSe/CdxZn1-xS (x = 0, 0.5, 1) QDs, we demonstrate the different role played by hot and cold carrier trapping rates in determining fluorescence quantum yields. Finally, the use of global analysis allows us untangling the complex ultrafast transient absorption signals. Smoothing of interface potential, together with effective surface passivation, appear to be crucial factors in slowing down both Auger-based and exciton trapping recombination processes.

Physical State of Ices in the Outer Solar System. Revised

NASA Technical Reports Server (NTRS)

Roush, Ted L.; DeVincenzi, Donald (Technical Monitor)

2001-01-01

Comparison of the identity and abundances of ices observed around protostars and those associated with comets clearly suggests that comets preserve the heritage of the interstellar materials that aggregated to form them. However, the ability to identify these same species on icy satellites in the outer solar system is a complex function of the composition of the original ices, their subsequent thermal histories, and their exposure to various radiation environments. Our ability to identify the ices currently present on objects in the outer solar system relies upon observational and laboratory, and theoretical efforts. To date there is ample observational evidence for crystalline water ice throughout the outer solar system. In addition, there is growing evidence that amorphous ice may be present on some bodies. More volatile ices, e.g. N2, CH4. CO, and other species, e.g. ammonia hydrate, are identified on objects lying at and beyond Uranus. Both photolysis and radiolysis play important roles in altering the original surfaces due to chemical reactions and erosion of the surface. Ultraviolet photolysis appears to dominate alteration of the upper few hundred Angstroms, although sputtering the surface can sometimes be a significantly competitative process; dominating on icy surfaces embedded in a strong planetary magnetospheric field. There is growing observational evidence that the by-products of photolysis and radiolysis, suggested on a theoretical basis, are present on icy surfaces.

Film cooling for a closed loop cooled airfoil

DOEpatents

Burdgick, Steven Sebastian; Yu, Yufeng Phillip; Itzel, Gary Michael

2003-01-01

Turbine stator vane segments have radially inner and outer walls with vanes extending therebetween. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. At least one film cooling hole is defined through a wall of at least one of the cavities for flow communication between an interior of the cavity and an exterior of the vane. The film cooling hole(s) are defined adjacent a potential low LCF life region, so that cooling medium that bleeds out through the film cooling hole(s) reduces a thermal gradient in a vicinity thereof, thereby the increase the LCF life of that region.

Steam exit flow design for aft cavities of an airfoil

DOEpatents

Storey, James Michael; Tesh, Stephen William

2002-01-01

Turbine stator vane segments have inner and outer walls with vanes extending therebetween. The inner and outer walls have impingement plates. Steam flowing into the outer wall passes through the impingement plate for impingement cooling of the outer wall surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. A skirt or flange structure is provided for shielding the steam cooling impingement holes adjacent the inner wall aerofoil fillet region of the nozzle from the steam flow exiting the aft nozzle cavities. Moreover, the gap between the flash rib boss and the cavity insert is controlled to minimize the flow of post impingement cooling media therebetween. This substantially confines outflow to that exiting via the return channels, thus furthermore minimizing flow in the vicinity of the aerofoil fillet region that may adversely affect impingement cooling thereof.

Role of bond adaptability in the passivation of colloidal quantum dot solids.

PubMed

Thon, Susanna M; Ip, Alexander H; Voznyy, Oleksandr; Levina, Larissa; Kemp, Kyle W; Carey, Graham H; Masala, Silvia; Sargent, Edward H

2013-09-24

Colloidal quantum dot (CQD) solids are attractive materials for photovoltaic devices due to their low-cost solution-phase processing, high absorption cross sections, and their band gap tunability via the quantum size effect. Recent advances in CQD solar cell performance have relied on new surface passivation strategies. Specifically, cadmium cation passivation of surface chalcogen sites in PbS CQDs has been shown to contribute to lowered trap state densities and improved photovoltaic performance. Here we deploy a generalized solution-phase passivation strategy as a means to improving CQD surface management. We connect the effects of the choice of metal cation on solution-phase surface passivation, film-phase trap density of states, minority carrier mobility, and photovoltaic power conversion efficiency. We show that trap passivation and midgap density of states determine photovoltaic device performance and are strongly influenced by the choice of metal cation. Supported by density functional theory simulations, we propose a model for the role of cations, a picture wherein metals offering the shallowest electron affinities and the greatest adaptability in surface bonding configurations eliminate both deep and shallow traps effectively even in submonolayer amounts. This work illustrates the importance of materials choice in designing a flexible passivation strategy for optimum CQD device performance.

Charge carrier trapping and acoustic phonon modes in single CdTe nanowires.

PubMed

Lo, Shun Shang; Major, Todd A; Petchsang, Nattasamon; Huang, Libai; Kuno, Masaru K; Hartland, Gregory V

2012-06-26

Semiconductor nanostructures produced by wet chemical synthesis are extremely heterogeneous, which makes single particle techniques a useful way to interrogate their properties. In this paper the ultrafast dynamics of single CdTe nanowires are studied by transient absorption microscopy. The wires have lengths of several micrometers and lateral dimensions on the order of 30 nm. The transient absorption traces show very fast decays, which are assigned to charge carrier trapping into surface defects. The time constants vary for different wires due to differences in the energetics and/or density of surface trap sites. Measurements performed at the band edge compared to the near-IR give slightly different time constants, implying that the dynamics for electron and hole trapping are different. The rate of charge carrier trapping was observed to slow down at high carrier densities, which was attributed to trap-state filling. Modulations due to the fundamental and first overtone of the acoustic breathing mode were also observed in the transient absorption traces. The quality factors for these modes were similar to those measured for metal nanostructures, and indicate a complex interaction with the environment.

How the stiffness of the optical trap depends on the proximity of the dielectric interface

NASA Astrophysics Data System (ADS)

Jákl, Petr; Šerý, Mojmír; Liška, Miroslav; Zemánek, Pavel

2005-09-01

When a probe confined in a single focused laser beam approaches the surface, it is getting more influenced by the retroreflected beam. This beam interferes with the incident one and a weak standing wave (SW) is created, which slightly modulates the incident beam. We studied experimentally how this phenomena influences the optical trap properties if SW is created using surfaces of two different reflectivities. We used polystyrene probes of diameters 690 nm and 820 nm, tracked their positions with quadrant photodiode (QPD) and analysed their thermal motion to get the axial trap stiffness along optical axis.

Radially dependent angular acceleration of twisted light.

PubMed

Webster, Jason; Rosales-Guzmán, Carmelo; Forbes, Andrew

2017-02-15

While photons travel in a straight line at constant velocity in free space, the intensity profile of structured light may be tailored for acceleration in any degree of freedom. Here we propose a simple approach to control the angular acceleration of light. Using Laguerre-Gaussian modes as our twisted beams carrying orbital angular momentum, we show that superpositions of opposite handedness result in a radially dependent angular acceleration as they pass through a focus (waist plane). Due to conservation of orbital angular momentum, we find that propagation dynamics are complex despite the free-space medium: the outer part of the beam (rings) rotates in an opposite direction to the inner part (petals), and while the outer part accelerates, the inner part decelerates. We outline the concepts theoretically and confirm them experimentally. Such exotic structured light beams are topical due to their many applications, for instance in optical trapping and tweezing, metrology, and fundamental studies in optics.

Albedos of Small Hilda Asteroids

NASA Astrophysics Data System (ADS)

Ryan, Erin L.; Woodward, C. E.

2010-10-01

We present albedo results for 70 small Hilda dynamical family members detected by the Spitzer Space Telescope in multiple archival programs. This Spitzer data samples Hildas with diameters between 2 and 11 kilometers. Our preliminary analysis reveals that the mean geometric albedo for this sample is pv = 0.05, matching the mean albedo derived for large (20 to 160 km) Hilda asteroids observed by IRAS (Ryan and Woodward 2010). This mean albedo is significantly darker than the mean albedo of asteroids in the outer main belt (2.8 AU < a < 3.5 AU), possibly suggesting that these asteroids did not originate from the outer main belt . This is in direct conflict with some dynamical models which suggest that the HIldas are field asteroids trapped from an inward migration of Jupiter (Franklin et al. 2004), and may provide additional observation support for delivery of dark Kuiper Belt contaminants to the inner solar system as per the Nice Model (Levison et al. 2009).

Ice detector

NASA Technical Reports Server (NTRS)

Weinstein, Leonard M. (Inventor)

1988-01-01

An ice detector is provided for the determination of the thickness of ice on the outer surface on an object (e.g., aircraft) independently of temperature or the composition of the ice. First capacitive gauge, second capacitive gauge, and temperature gauge are embedded in embedding material located within a hollowed out portion of the outer surface. This embedding material is flush with the outer surface to prevent undesirable drag. The first capacitive gauge, second capacitive gauge, and the temperature gauge are respectively connected to first capacitive measuring circuit, second capacitive measuring circuit, and temperature measuring circuit. The geometry of the first and second capacitive gauges is such that the ratio of the voltage outputs of the first and second capacitance measuring circuits is proportional to the thickness of ice, regardless of ice temperature or composition. This ratio is determined by offset and dividing circuit.

Use of beam deflection to control an electron beam wire deposition process

NASA Technical Reports Server (NTRS)

Taminger, Karen M. (Inventor); Hofmeister, William H. (Inventor); Hafley, Robert A. (Inventor)

2013-01-01

A method for controlling an electron beam process wherein a wire is melted and deposited on a substrate as a molten pool comprises generating the electron beam with a complex raster pattern, and directing the beam onto an outer surface of the wire to thereby control a location of the wire with respect to the molten pool. Directing the beam selectively heats the outer surface of the wire and maintains the position of the wire with respect to the molten pool. An apparatus for controlling an electron beam process includes a beam gun adapted for generating the electron beam, and a controller adapted for providing the electron beam with a complex raster pattern and for directing the electron beam onto an outer surface of the wire to control a location of the wire with respect to the molten pool.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kidane, Getnet S; Desilva, Upul P.; He, Chengli

A gas turbine includes first and second parts having outer surfaces located adjacent to each other to create an interface where wear occurs. A wear probe is provided for monitoring wear of the outer surface of the first part, and includes an optical guide having first and second ends, wherein the first end is configured to be located flush with the outer surface of the first part. A fiber bundle includes first and second ends, the first end being located proximate to the second end of the optical guide. The fiber bundle includes a transmit fiber bundle comprising a firstmore » plurality of optical fibers coupled to a light source, and a receive fiber bundle coupled to a light detector and configured to detect reflected light. A processor is configured to determine a length of the optical guide based on the detected reflected light.« less

Cured composite materials for reactive metal battery electrolytes

DOEpatents

Harrup, Mason K.; Stewart, Frederick F.; Peterson, Eric S.

2006-03-07

A solid molecular composite polymer-based electrolyte is made for batteries, wherein silicate compositing produces a electrolytic polymer with a semi-rigid silicate condensate framework, and then mechanical-stabilization by radiation of the outer surface of the composited material is done to form a durable and non-tacky texture on the electrolyte. The preferred ultraviolet radiation produces this desirable outer surface by creating a thin, shallow skin of crosslinked polymer on the composite material. Preferably, a short-duration of low-medium range ultraviolet radiation is used to crosslink the polymers only a short distance into the polymer, so that the properties of the bulk of the polymer and the bulk of the molecular composite material remain unchanged, but the tough and stable skin formed on the outer surface lends durability and processability to the entire composite material product.

Trapping of hydrogen atoms in X-irradiated salts at room temperature and the decay kinetics

NASA Technical Reports Server (NTRS)

May, C. E.; Philipp, W. H.; Marsik, S. J.

1974-01-01

The salts (hypophosphites, formates, a phosphite, a phosphate, and an oxalate) were X-irradiated, whereby hydrogen formed chemically by a radiolytic process becomes trapped in the solid. By room temperature vacuum extraction, the kinetics for the evolution of this trapped hydrogen was studied mass spectrometrically. All salts except two exhibited second-order kinetics. The two exceptions (NaH2PO2(H2O) and K2HPO4) showed first-order kinetics. Based on experimental results, the escape of hydrogen involves three steps: the diffusion of hydrogen atoms from the bulk to the surface, association of these atoms on the surface (rate controlling step for second-order hydrogen evolution), and the desorption of molecular hydrogen from the surface. The hydrogen does not escape if the irradiated salt is stored in air, apparently because adsorbed air molecules occupy surface sites required in the escape mechanism.

Field-free junctions for surface electrode ion traps

NASA Astrophysics Data System (ADS)

Jordens, Robert; Schmied, R.; Blain, M. G.; Leibfried, D.; Wineland, D.

2015-05-01

Intersections between transport guides in a network of RF ion traps are a key ingredient to many implementations of scalable quantum information processing with trapped ions. Several junction architectures demonstrated so far are limited by varying radial secular frequencies, a reduced trap depth, or a non-vanishing RF field along the transport channel. We report on the design and progress in implementing a configurable microfabricated surface electrode Y-junction that employs switchable RF electrodes. An essentially RF-field-free pseudopotential guide between any two legs of the junction can be established by applying RF potential to a suitable pair of electrodes. The transport channel's height above the electrodes, its depth and radial curvature are constant to within 15%. Supported by IARPA, Sandia, NSA, ONR, and the NIST Quantum Information Program.

Triple-glazed insulating unit with improved edge insulation

DOEpatents

Goodwin, George B.; Buchanan, Michael J.

2016-06-07

An insulating unit includes a first spacer frame between first and second sheets, e.g. glass sheets, and a second spacer frame between the second sheet and a third sheet. A first surface of the first spacer frame is adhered to inner surface of the first sheet, and an opposite second surface of the first spacer frame is adhered to a first surface of the second sheet, by a moisture impervious adhesive layer. A first outer surface of the second spacer frame is adhered to a second surface of the second sheet, and an opposite second outer surface of the second spacer frame is adhered to an inner surface of the third sheet, by the adhesive layer. The first spacer frame and the second spacer frame have an offset of greater than zero.

Ceramic molar crown reproducibility by digital workflow manufacturing: An in vitro study

PubMed Central

Kim, Chong-Myeong

2017-01-01

PURPOSE This in vitro study aimed to analyze and compare the reproducibility of zirconia and lithium disilicate crowns manufactured by digital workflow. MATERIALS AND METHODS A typodont model with a prepped upper first molar was set in a phantom head, and a digital impression was obtained with a video intraoral scanner (CEREC Omnicam; Sirona GmbH), from which a single crown was designed and manufactured with CAD/CAM into a zirconia crown and lithium disilicate crown (n=12). Reproducibility of each crown was quantitatively retrieved by superimposing the digitized data of the crown in 3D inspection software, and differences were graphically mapped in color. Areas with large differences were analyzed with digital microscopy. Mean quadratic deviations (RMS) quantitatively obtained from each ceramic group were statistically analyzed with Student's t-test (α=.05). RESULTS The RMS value of lithium disilicate crown was 29.2 (4.1) µm and 17.6 (5.5) µm on the outer and inner surfaces, respectively, whereas these values were 18.6 (2.0) µm and 20.6 (5.1) µm for the zirconia crown. Reproducibility of zirconia and lithium disilicate crowns had a statistically significant difference only on the outer surface (P<.001). The outer surface of lithium disilicate crown showed over-contouring on the buccal surface and under-contouring on the inner occlusal surface. The outer surface of zirconia crown showed both over- and under-contouring on the buccal surface, and the inner surface showed under-contouring in the marginal areas. CONCLUSION Restoration manufacturing by digital workflow will enhance the reproducibility of zirconia single crowns more than that of lithium disilicate single crowns. PMID:28874991

Impact of slow-release Bacillus sphaericus granules on mosquito populations followed in a tropical urban environment.

PubMed

Skovmand, Ole; Ouedraogo, Thierry D A; Sanogo, Edith; Samuelsen, Helle; Toé, Lea P; Baldet, Thierry

2009-01-01

A floating, slow-release, granular formulation of Bacillus sphaericus (Neide) was used to control mosquito larvae in two suburban areas of two tropical cities: Ouagadougou and Bobo-Dioulasso, Burkina Faso. A circular area of 2 km2, diameter 1,600 m, was treated in each city using a similar, smaller area 1 km away as an untreated control. Mosquito captures were made in houses in four concentric circles, from the periphery to the center; each circle was 50 m in width. Mosquitoes were captured in CDC light traps or from human landings. More than 95% of the mosquitoes were Culex quinquefasciatus (Say) (Diptera: Culicidae). The human landing catches provided twice as many mosquitoes as did the CDC traps/night/house. The treatments resulted in important reductions relative to the control area and to preintervention captures. The reduction was more prominent in the inner circle (up to 90%) than in the outer circle (50-70%), presumably because of the impact of immigrating mosquitoes from nontreated breeding sites around the intervention area. This effect was more pronounced for light trap catches than from human landings. The impact of treatment was also measured as the mean ratio of mosquito density in the two outer circles to that of the two inner circles. This ratio was approximately 1:1 before the intervention and reached 1:0.43 during the intervention. This comparison does not depend on the assumption that, in the absence of intervention, the mosquito population development in the two areas would have been identical, but does depend on the homogeneity of the intervention area. The study showed that it is possible to organize mosquito control in a tropical, urban environment by forming and rapidly training teams of young people to carry out the mosquito control mostly using a biopesticide that can be applied without any tools except an iron bar to lift lids on some cesspits.

On-chip photonic tweezers for photonics, microfluidics, and biology

NASA Astrophysics Data System (ADS)

Pin, Christophe; Renaut, Claude; Tardif, Manon; Jager, Jean-Baptiste; Delamadeleine, Eric; Picard, Emmanuel; Peyrade, David; Hadji, Emmanuel; de Fornel, Frédérique; Cluzel, Benoît

2017-04-01

Near-field optical forces arise from evanescent electromagnetic fields and can be advantageously used for on-chip optical trapping. In this work, we investigate how evanescent fields at the surface of photonic cavities can efficiently trap micro-objects such as polystyrene particles and bacteria. We study first the influence of trapped particle's size on the trapping potential and introduce an original optofluidic near-field optical microscopy technique. Then we analyze the rotational motion of trapped clusters of microparticles and investigate their possible use as microfluidic micro-tools such as integrated micro-flow vane. Eventually, we demonstrate efficient on-chip optical trapping of various kinds of bacteria.

Novel Outer Membrane Protein Involved in Cellulose and Cellooligosaccharide Degradation by Cytophaga hutchinsonii

PubMed Central

Ji, Xiaofei; Wang, Ying; Zhang, Cong; Bai, Xinfeng; Zhang, Weican

2014-01-01

Cytophaga hutchinsonii is an aerobic cellulolytic soil bacterium which was reported to use a novel contact-dependent strategy to degrade cellulose. It was speculated that cellooligosaccharides were transported into the periplasm for further digestion. In this study, we reported that most of the endoglucanase and β-glucosidase activity was distributed on the cell surface of C. hutchinsonii. Cellobiose and part of the cellulose could be hydrolyzed to glucose on the cell surface. However, the cell surface cellulolytic enzymes were not sufficient for cellulose degradation by C. hutchinsonii. An outer membrane protein, CHU_1277, was disrupted by insertional mutation. Although the mutant maintained the same endoglucanase activity and most of the β-glucosidase activity, it failed to digest cellulose, and its cellooligosaccharide utilization ability was significantly reduced, suggesting that CHU_1277 was essential for cellulose degradation and played an important role in cellooligosaccharide utilization. Further study of cellobiose hydrolytic ability of the mutant on the enzymatic level showed that the β-glucosidase activity in the outer membrane of the mutant was not changed. It revealed that CHU_1277 played an important role in assisting cell surface β-glucosidase to exhibit its activity sufficiently. Studies on the outer membrane proteins involved in cellulose and cellooligosaccharide utilization could shed light on the mechanism of cellulose degradation by C. hutchinsonii. PMID:24837387

A Preliminary Study on the Pattern, the Physiological Bases and the Molecular Mechanism of the Adductor Muscle Scar Pigmentation in Pacific Oyster Crassostrea gigas

PubMed Central

Yu, Wenchao; He, Cheng; Cai, Zhongqiang; Xu, Fei; Wei, Lei; Chen, Jun; Jiang, Qiuyun; Wei, Na; Li, Zhuang; Guo, Wen; Wang, Xiaotong

2017-01-01

The melanin pigmentation of the adductor muscle scar and the outer surface of the shell are among attractive features and their pigmentation patterns and mechanism still remains unknown in the Pacific oyster Crassostrea gigas. To study these pigmentation patterns, the colors of the adductor muscle scar vs. the outer surface of the shell on the same side were compared. No relevance was found between the colors of the adductor muscle scars and the corresponding outer surface of the shells, suggesting that their pigmentation processes were independent. Interestingly, a relationship between the color of the adductor muscle scars and the dried soft-body weight of Pacific oysters was found, which could be explained by the high hydroxyl free radical scavenging capacity of the muscle attached to the black adductor muscle scar. After the transcriptomes of pigmented and unpigmented adductor muscles and mantles were studied by RNAseq and compared, it was found that the retinol metabolism pathway were likely to be involved in melanin deposition on the adductor muscle scar and the outer surface of the shell, and that the different members of the tyrosinase or Cytochrome P450 gene families could play a role in the independent pigmentation of different organs. PMID:28955252

Electromagnetic radiation trapped in the magnetosphere above the plasma frequency

NASA Technical Reports Server (NTRS)

Gurnett, D. A.; Shaw, R. R.

1973-01-01

An electromagnetic noise band is frequently observed in the outer magnetosphere by the Imp 6 spacecraft at frequencies from about 5 to 20 kHz. This noise band generally extends throughout the region from near the plasmapause boundary to near the magnetopause boundary. The noise typically has a broadband field strength of about 5 microvolts/meter. The noise band often has a sharp lower cutoff frequency at about 5 to 10 kHz, and this cutoff has been identified as the local electron plasma frequency. Since the plasma frequency in the plasmasphere and solar wind is usually above 20 kHz, it is concluded that this noise must be trapped in the low-density region between the plasmapause and magnetopause boundaries. The noise bands often contain a harmonic frequency structure which suggests that the radiation is associated with harmonics of the electron cyclotron frequency.

Fingerprint-Inspired Flexible Tactile Sensor for Accurately Discerning Surface Texture.

PubMed

Cao, Yudong; Li, Tie; Gu, Yang; Luo, Hui; Wang, Shuqi; Zhang, Ting

2018-04-01

Inspired by the epidermal-dermal and outer microstructures of the human fingerprint, a novel flexible sensor device is designed to improve haptic perception and surface texture recognition, which is consisted of single-walled carbon nanotubes, polyethylene, and polydimethylsiloxane with interlocked and outer micropyramid arrays. The sensor shows high pressure sensitivity (-3.26 kPa -1 in the pressure range of 0-300 Pa), and it can detect the shear force changes induced by the dynamic interaction between the outer micropyramid structure on the sensor and the tested material surface, and the minimum dimension of the microstripe that can be discerned is as low as 15 µm × 15 µm (interval × width). To demonstrate the texture discrimination capability, the sensors are tested for accurately discerning various surface textures, such as the textures of different fabrics, Braille characters, the inverted pyramid patterns, which will have great potential in robot skins and haptic perception, etc. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Giant Planet Satellite Exospheres

NASA Technical Reports Server (NTRS)

McGrath, Melissa A.

2014-01-01

Exospheres are relatively common in the outer solar system among the moons of the gas giant planets. They span the range from very tenuous, surface-bounded exospheres (e.g., Rhea, Dione) to quite robust exospheres with exobase above the surface (e.g., lo, Triton), and include many intermediate cases (e.g., Europa, Ganymede, Enceladus). The exospheres of these moons exhibit an interesting variety of sources, from surface sputtering, to frost sublimation, to active plumes, and also well illustrate another common characteristic of the outer planet satellite exospheres, namely, that the primary species often exists both as a gas in atmosphere, and a condensate (frost or ice) on the surface. As described by Yelle et al. (1995) for Triton, "The interchange of matter between gas and solid phases on these bodies has profound effects on the physical state of the surface and the structure of the atmosphere." A brief overview of the exospheres of the outer planet satellites will be presented, including an inter-comparison of these satellites exospheres with each other, and with the exospheres of the Moon and Mercury.

Outer-sphere Pb(II) adsorbed at specific surface sites on single crystal α-alumina

USGS Publications Warehouse

Bargar, John R.; Towle, Steven N.; Brown, Gordon E.; Parks, George A.

1996-01-01

Solvated Pb(II) ions were found to adsorb as structurally well-defined outer-sphere complexes at specific sites on the α-Al2O3 (0001) single crystal surface, as determined by grazing-incidence X-ray absorption fine structure (GI-XAFS) measurements. The XAFS results suggest that the distance between Pb(II) adions and the alumina surface is approximately 4.2 Å. In contrast, Pb(II) adsorbs as more strongly bound inner-sphere complexes on α-Al2O3 (102). The difference in reactivities of the two alumina surfaces has implications for modeling surface complexation reactions of contaminants in natural environments, catalysis, and compositional sector zoning of oxide crystals.

The DUV Stability of Superlattice-Doped CMOS Detector Arrays

NASA Technical Reports Server (NTRS)

Hoenk, M. E.; Carver, A.; Jones, T.; Dickie, M.; Cheng, P.; Greer, H. F.; Nikzad, S.; Sgro, J.

2013-01-01

In this paper, we present experimental results and band structure calculations that illuminate the unique properties of superlattice-doped detectors. Numerical band structure calculations are presented to analyze the dependencies of surface passivation on dopant profiles and interface trap densities (Figure 3). Experiments and calculations show that quantum-engineered surfaces, grown at JPL by low temperature molecular beam epitaxy, achieve a qualitative as well as quantitative uniqueness in their near-immunity to high densities of surface and interface traps.

Evaluation and improvement of sticky traps as monitoring tools for Glossina austeni and G. brevipalpis (Diptera: Glossinidae) in north-eastern KwaZulu-Natal, South Africa.

PubMed

Green, K Kappmeier; Venter, G J

2007-12-01

The attractiveness of various colours, colour combinations and sizes of sticky traps of the 3-dimensional trap (3DT), cross-shaped target (XT), rectangular screen (RT) and monopanels were evaluated for their efficacy to capture Glossina austeni Newstead and G. brevipalpis Newstead in north-eastern KwaZulu-Natal, South Africa. The 3-dimensional shapes of the XT and 3DT in light blue (l.blue) and white were significantly (ca. 3.1-6.9 times) better than the RT for G. austeni. On bicoloured XTs, G. austeni landed preferentially on electric blue (e.blue) (58%) and black (63%) surfaces when used with white; while for G. brevipalpis, significantly more landed on e.blue (60-66%) surfaces when used with l.blue, black or white surfaces. Increased trap size increased the catches of G. brevipalpis females and both sexes of G. austeni significantly. Temoocid and polybutene sticky materials were equally effective and remained durable for 2-3 weeks. The glossy shine of trap surfaces did not have any significant effect on the attraction and landing responses of the two species. The overall trap efficiency of the e.blue/l.blue XT was 23% for G. brevipalpis and 28% for G. austeni, and that of the e.blue/black XT was 16% for G. brevipalpis and 51% for G. austeni. Larger monopanels, painted e.blue/black on both sides, increased the catches of G. austeni females significantly by up to four times compared to the standard e.blue/black XT. This monopanel would be recommended for use as a simple and cost effective survey tool for both species in South Africa.

Disk filter

DOEpatents

Bergman, Werner

1986-01-01

An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

Article having an improved platinum-aluminum-hafnium protective coating

NASA Technical Reports Server (NTRS)

Nagaraj, Bangalore Aswatha (Inventor); Williams, Jeffrey Lawrence (Inventor)

2005-01-01

An article protected by a protective coating has a substrate and a protective coating having an outer layer deposited upon the substrate surface and a diffusion zone formed by interdiffusion of the outer layer and the substrate. The protective coating includes platinum, aluminum, no more than about 2 weight percent hafnium, and substantially no silicon. The outer layer is substantially a single phase.

Disk filter

DOEpatents

Bergman, W.

1985-01-09

An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

Effect of interstitial impurities on the field dependent microwave surface resistance of niobium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinello, M., E-mail: mmartine@fnal.gov; Checchin, M.; Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616

Previous work has demonstrated that the radio frequency surface resistance of niobium resonators is dramatically reduced when nitrogen impurities are dissolved as interstitial in the material. This effect is attributed to the lowering of the Mattis-Bardeen surface resistance with increasing accelerating field; however, the microscopic origin of this phenomenon is poorly understood. Meanwhile, an enhancement of the sensitivity to trapped magnetic field is typically observed for such cavities. In this paper, we conduct a systematic study on these different components contributing to the total surface resistance as a function of different levels of dissolved nitrogen, in comparison with standard surfacemore » treatments for niobium resonators. Adding these results together, we are able to show which is the optimum surface treatment that maximizes the Q-factor of superconducting niobium resonators as a function of expected trapped magnetic field in the cavity walls. These results also provide insights on the physics behind the change in the field dependence of the Mattis-Bardeen surface resistance, and of the trapped magnetic vortex induced losses in superconducting niobium resonators.« less

Abnormal Multiple Charge Memory States in Exfoliated Few-Layer WSe2 Transistors.

PubMed

Chen, Mikai; Wang, Yifan; Shepherd, Nathan; Huard, Chad; Zhou, Jiantao; Guo, L J; Lu, Wei; Liang, Xiaogan

2017-01-24

To construct reliable nanoelectronic devices based on emerging 2D layered semiconductors, we need to understand the charge-trapping processes in such devices. Additionally, the identified charge-trapping schemes in such layered materials could be further exploited to make multibit (or highly desirable analog-tunable) memory devices. Here, we present a study on the abnormal charge-trapping or memory characteristics of few-layer WSe 2 transistors. This work shows that multiple charge-trapping states with large extrema spacing, long retention time, and analog tunability can be excited in the transistors made from mechanically exfoliated few-layer WSe 2 flakes, whereas they cannot be generated in widely studied few-layer MoS 2 transistors. Such charge-trapping characteristics of WSe 2 transistors are attributed to the exfoliation-induced interlayer deformation on the cleaved surfaces of few-layer WSe 2 flakes, which can spontaneously form ambipolar charge-trapping sites. Our additional results from surface characterization, charge-retention characterization at different temperatures, and density functional theory computation strongly support this explanation. Furthermore, our research also demonstrates that the charge-trapping states excited in multiple transistors can be calibrated into consistent multibit data storage levels. This work advances the understanding of the charge memory mechanisms in layered semiconductors, and the observed charge-trapping states could be further studied for enabling ultralow-cost multibit analog memory devices.

Graphene-edge dielectrophoretic tweezers for trapping of biomolecules.

PubMed

Barik, Avijit; Zhang, Yao; Grassi, Roberto; Nadappuram, Binoy Paulose; Edel, Joshua B; Low, Tony; Koester, Steven J; Oh, Sang-Hyun

2017-11-30

The many unique properties of graphene, such as the tunable optical, electrical, and plasmonic response make it ideally suited for applications such as biosensing. As with other surface-based biosensors, however, the performance is limited by the diffusive transport of target molecules to the surface. Here we show that atomically sharp edges of monolayer graphene can generate singular electrical field gradients for trapping biomolecules via dielectrophoresis. Graphene-edge dielectrophoresis pushes the physical limit of gradient-force-based trapping by creating atomically sharp tweezers. We have fabricated locally backgated devices with an 8-nm-thick HfO 2 dielectric layer and chemical-vapor-deposited graphene to generate 10× higher gradient forces as compared to metal electrodes. We further demonstrate near-100% position-controlled particle trapping at voltages as low as 0.45 V with nanodiamonds, nanobeads, and DNA from bulk solution within seconds. This trapping scheme can be seamlessly integrated with sensors utilizing graphene as well as other two-dimensional materials.

Technology for On-Chip Qubit Control with Microfabricated Surface Ion Traps

DOE Office of Scientific and Technical Information (OSTI.GOV)

Highstrete, Clark; Scott, Sean Michael; Nordquist, Christopher D.

2013-11-01

Trapped atomic ions are a leading physical system for quantum information processing. However, scalability and operational fidelity remain limiting technical issues often associated with optical qubit control. One promising approach is to develop on-chip microwave electronic control of ion qubits based on the atomic hyperfine interaction. This project developed expertise and capabilities at Sandia toward on-chip electronic qubit control in a scalable architecture. The project developed a foundation of laboratory capabilities, including trapping the 171Yb + hyperfine ion qubit and developing an experimental microwave coherent control capability. Additionally, the project investigated the integration of microwave device elements with surface ionmore » traps utilizing Sandia’s state-of-the-art MEMS microfabrication processing. This effort culminated in a device design for a multi-purpose ion trap experimental platform for investigating on-chip microwave qubit control, laying the groundwork for further funded R&D to develop on-chip microwave qubit control in an architecture that is suitable to engineering development.« less

Sequential planet formation in transition disks: The case of HD 100546

NASA Astrophysics Data System (ADS)

Pinilla, Paola; Birnsitel, Til; Walsh, Catherine; van Dishoeck, Ewine

2015-08-01

Transition disks are circumstellar disks with dust inner cavities and may reveal an intermediate step of the ongoing disk dispersal process, where planet formation might happen. The recent gas and dust observations of transition disks have given major support to the presence of massive planets in transition disks. The analysis of such observations help to constrain the properties of the potential unseen planets. An excellent candidate to analyse the dust evolution when planets are embedded in disks is the transition disk around the Herbig Ae star HD 100546. Near-infrared observations of HD 100546 suggested the presence on an inner planet at 10 AU distance from the star (e.g. Mulders et al. 2013), while an outer planet has been directly imaged at 70 AU distance, which may be in the act of formation (Quant et al. 2013, 2015; Currie et al. 2014). The two embedded planets can lead to remarkable dust structures due to the particle trapping at the edges of the gaps caved by such planets (e.g. Pinilla et al. 2012, 2015). Recent ALMA Cycle 0 observations of this disk reveal a two-ring like structure consistent with particle trapping induced by the two companions (Walsh et al. 2014). The comparison of these observations with dust evolution models, that include the coagulation and fragmentation of dust grains, suggest that the outer companion must be at least two million of years younger than the inner companion, revealing sequential planet formation in this disk (Pinilla et al. 2015, under revision).

Microwave Brightness Of Land Surfaces From Outer Space

NASA Technical Reports Server (NTRS)

Kerr, Yann H.; Njoku, Eni G.

1991-01-01

Mathematical model approximates microwave radiation emitted by land surfaces traveling to microwave radiometer in outer space. Applied to measurements made by Scanning Multichannel Microwave Radiometer (SMMR). Developed for interpretation of microwave imagery of Earth to obtain distributions of various chemical, physical, and biological characteristics across its surface. Intended primarily for use in mapping moisture content of soil and fraction of Earth covered by vegetation. Advanced Very-High-Resolution Radiometer (AVHRR), provides additional information on vegetative cover, thereby making possible retrieval of soil-moisture values from SMMR measurements. Possible to monitor changes of land surface during intervals of 5 to 10 years, providing significant data for mathematical models of evolution of climate.

Advanced methods for light trapping in optically thin silicon solar cells

NASA Astrophysics Data System (ADS)

Nagel, James Richard

2011-12-01

The field of light trapping is the study of how best to absorb light in a thin film of material when most light either reflects away at the surface or transmits straight through to the other side. This has tremendous application to the field of photovoltaics where thin silicon films can be manufactured cheaply, but also fail to capture all of the available photons in the solar spectrum. Advancements in light trapping therefore bring us closer to the day when photovoltaic devices may reach grid parity with traditional fossil fuels on the electrical energy market. This dissertation advances our understanding of light trapping by first modeling the effects of loss in planar dielectric waveguides. The mathematical framework developed here can be used to model any arbitrary three-layer structure with mixed gain or loss and then extract the total field solution for the guided modes. It is found that lossy waveguides possess a greater number of eigenmodes than their lossless counterparts, and that these "loss guided" modes attenuate much more rapidly than conventional modes. Another contribution from this dissertation is the exploration of light trapping through the use of dielectric nanospheres embedded directly within the active layer of a thin silicon film. The primary benefit to this approach is that the device can utilize a surface nitride layer serving as an antireflective coating while still retaining the benefits of light trapping within the film. The end result is that light trapping and light injection are effectively decoupled from each other and may be independently optimized within a single photovoltaic device. The final contribution from this work is a direct numerical comparison between multiple light trapping schemes. This allows us to quantify the relative performances of various design techniques against one another and objectively determine which ideas tend to capture the most light. Using numerical simulation, this work directly compares the absorption gains due to embedded nanoparticles, surface textures, antireflective coatings, and plasmonic nanospheres. This work also introduces a new mathematical metric for differentiating between index matching and angular scattering at a textured surface. Such information will prove useful in guiding future scientific efforts in the fields of light trapping and light management in thin film photovoltaics.

Confocal Raman microscopy for monitoring chemical reactions on single optically trapped, solid-phase support particles.

PubMed

Houlne, Michael P; Sjostrom, Christopher M; Uibel, Rory H; Kleimeyer, James A; Harris, Joel M

2002-09-01

Optical trapping of small structures is a powerful tool for the manipulation and investigation of colloidal and particulate materials. The tight focus excitation requirements of optical trapping are well suited to confocal Raman microscopy. In this work, an inverted confocal Raman microscope is developed for studies of chemical reactions on single, optically trapped particles and applied to reactions used in solid-phase peptide synthesis. Optical trapping and levitation allow a particle to be moved away from the coverslip and into solution, avoiding fluorescence interference from the coverslip. More importantly, diffusion of reagents into the particle is not inhibited by a surface, so that reaction conditions mimic those of particles dispersed in solution. Optical trapping and levitation also maintain optical alignment, since the particle is centered laterally along the optical axis and within the focal plane of the objective, where both optical forces and light collection are maximized. Hour-long observations of chemical reactions on individual, trapped silica particles are reported. Using two-dimensional least-squares analysis methods, the Raman spectra collected during the course of a reaction can be resolved into component contributions. The resolved spectra of the time-varying species can be observed, as they bind to or cleave from the particle surface.

Modeling the Stability of Volatile Deposits in Lunar Cold Traps

NASA Technical Reports Server (NTRS)

Crider, D. H.; Vondrak, R. R.

2002-01-01

There are several mechanisms acting at the cold traps that can alter the inventory of volatiles there. Primarily, the lunar surface is bombarded by meteoroids which impact, melt, process, and redistribute the regolith. Further, solar wind and magnetospheric ion fluxes are allowed limited access onto the regions in permanent shadow. Also, although cold traps are in the permanent shadow of the Sun, there is a small flux of radiation incident on the regions from interstellar sources. We investigate the effects of these space weathering processes on a deposit of volatiles in a lunar cold trap through simulations. We simulate the development of a column of material near the surface of the Moon resulting from space weathering. This simulation treats a column of material at a lunar cold trap and focuses on the hydrogen content of the column. We model space weathering processes on several time and spatial scales to simulate the constant rain of micrometeoroids as well as sporadic larger impactors occurring near the cold traps to determine the retention efficiency of the cold traps. We perform the Monte Carlo simulation over many columns of material to determine the expectation value for hydrogen content of the top few meters of soil for comparison with Lunar Prospector neutron data.

Loading an Optical Trap with Diamond Nanocrystals Containing Nitrogen-Vacancy Centers from a Surface

NASA Astrophysics Data System (ADS)

Hsu, Jen-Feng; Ji, Peng; Dutt, M. V. Gurudev; D'Urso, Brian R.

2015-03-01

We present a simple and effective method of loading particles into an optical trap. Our primary application of this method is loading photoluminescent material, such as diamond nanocrystals containing nitrogen-vacancy (NV) centers, for coupling the mechanical motion of the trapped crystal with the spin of the NV centers. Highly absorptive material at the trapping laser frequency, such as tartrazine dye, is used as media to attach nanodiamonds and burn into a cloud of air-borne particles as the material is swept near the trapping laser focus on a glass slide. Particles are then trapped with the laser used for burning or transferred to a second laser trap at a different wavelength. Evidence of successful loading diamond nanocrystals into the trap presented includes high sensitivity of the photoluminecscence (PL) to the excitation laser and the PL spectra of the optically trapped particles

Optical trapping assembling of clusters and nanoparticles in solution by CW and femtosecond lasers

NASA Astrophysics Data System (ADS)

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

2015-02-01

Laser trapping of molecular systems in solution is classified into three cases: JUST TRAPPING, EXTENDED TRAPPING, and NUCLEATION and GROWTH. The nucleation in amino acid solutions depends on where the 1064-nm CW trapping laser is focused, and crystallization and liquid-liquid phase separation are induced by laser trapping at the solution/air surface and the solution/glass interface, respectively. Laser trapping crystallization is achieved even in unsaturated solution, on which unique controls of crystallization are made possible. Crystal size is arbitrarily controlled by tuning laser power for a plate-like anhydrous crystal of l-phenylalanine. The α- or γ-crystal polymorph of glycine is selectively prepared by changing laser power and polarization. Further efficient trapping of nanoparticles and their following ejection induced by femtosecond laser pulses are introduced as unique trapping phenomena and finally future perspective is presented.

Integrated gas turbine engine-nacelle

NASA Technical Reports Server (NTRS)

Adamson, A. P.; Sargisson, D. F.; Stotler, C. L., Jr. (Inventor)

1979-01-01

A nacelle for use with a gas turbine engine is provided with an integral webbed structure resembling a spoked wheel for rigidly interconnecting the nacelle and engine. The nacelle is entirely supported in its spacial relationship with the engine by means of the webbed structure. The inner surface of the nacelle defines the outer limits of the engine motive fluid flow annulus, while the outer surface of the nacelle defines a streamlined envelope for the engine.

Method for manufacturing a rotor having superconducting coils

DOEpatents

Driscoll, David I.; Shoykhet, Boris A.

2001-01-01

A method and apparatus for manufacturing a rotor for use with a rotating machine is provided that employs a superconducting coil on the rotor. An adhesive is applied to an outer surface of the rotor body, which may include a groove disposed within an outer surface of the rotor body. A superconducting coil is then mounted onto the rotor body such that the adhesive bonds the superconducting coil to the rotor body.

Lathe Attachment Finishes Inner Surface of Tubes

NASA Technical Reports Server (NTRS)

Lancki, A. J.

1982-01-01

Extremely smooth finishes are machined on inside surfaces of tubes by new attachment for a lathe. The relatively inexpensive accessory, called a "microhone," holds a honing stone against workpiece by rigid tangs instead of springs as in conventional honing tools. Inner rod permits adjustment of microhoning stone, while outer tube supports assembly. Outer tube is held between split blocks on lathe toolpost. Microhoning can be done with either microhone or workpiece moving and other member stationary.

Ultra high performance connectors for power transmission applications

DOEpatents

Wang, Jy-An; Ren, Fei; Lee, Dominic F; Jiang, Hao

2014-03-04

Disclosed are several examples of an apparatus for connecting the free ends of two electrical power transmission lines having conductor strands disposed around a central, reinforcing core. The examples include an inner sleeve having a body defining an inner bore passing through an axially-extending, central axis, an outer rim surface disposed radially outward from the central bore, and one or more axially-extending grooves penetrating the body at the outer rim surface. Also included is an outer splice having a tubular shaped body with a bore passing coaxially through the central axis, the bore defining an inner rim surface for accepting the inner sleeve. The inner bore of the inner sleeve accepts the reinforcement cores of the two conductors, and the grooves accept the conductor strands in an overlapping configuration so that a majority of the electrical current flows between the overlapped conductor strands when the conductors are transmitting electrical current.

Theoretical studies of volatile processes in the outer solar system

NASA Technical Reports Server (NTRS)

Lunine, Jonathan I.

1991-01-01

Four studies of volatile processes in the outer solar system are discussed. Researchers suggest that the convective and conductive regions of Triton's atmosphere join at the tropopause near 10 km. A model of volatile transport on Triton's surface was constructed that predicts that Triton's surface north of 15 degrees north latitude is experiencing deposition of nitrogen frosts, as are the bright portions of the south polar cap near the equator. Also discussed are numerical models of the evolution of Titan's surface and atmosphere. Results of a study of the rheology of ammonia-water liquids were applied to the icy satellites of the outer solar system. Finally, the researchers examined the frictional heating, sublimation, and re-condensation of grains free-falling into the solar nebula from a surrounding interstellar cloud. The sublimation model includes the effect of various volatile species and accounts for the poor radiating properties of small grains using Mie theory.

Adsorption mechanisms of selenium oxyanions at the aluminum oxide/water interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peak, Derek

2008-06-09

Sorption processes at the mineral/water interface typically control the mobility and bioaccessibility of many inorganic contaminants such as oxyanions. Selenium is an important micronutrient for human and animal health, but at elevated concentrations selenium toxicity is a concern. The objective of this study was to determine the bonding mechanisms of selenate (SeO{sub 4}{sup 2-}) and selenite (SeO{sub 3}{sup 2-}) on hydrous aluminum oxide (HAO) over a wide range of reaction pH using extended X-ray absorption fine structure (EXAFS) spectroscopy. Additionally, selenate adsorption on corundum ({alpha}-Al{sub 2}O{sub 3}) was studied to determine if adsorption mechanisms change as the aluminum oxide surfacemore » structure changes. The overall findings were that selenite forms a mixture of outer-sphere and inner-sphere bidentate-binuclear (corner-sharing) surface complexes on HAO, selenate forms primarily outer-sphere surface complexes on HAO, and on corundum selenate forms outer-sphere surface complexes at pH 3.5 but inner-sphere monodentate surface complexes at pH 4.5 and above. It is possible that the lack of inner-sphere complex formation at pH 3.5 is caused by changes in the corundum surface at low pH or secondary precipitate formation. The results are consistent with a structure-based reactivity for metal oxides, wherein hydrous metal oxides form outer-sphere complexes with sulfate and selenate, but inner-sphere monodentate surface complexes are formed between sulfate and selenate and {alpha}-Me{sub 2}O{sub 3}.« less

Blood pressure cuffs as a vector for transmission of multi-resistant organisms: colonisation rates and effects of disinfection.

PubMed

Grewal, Harjeet; Varshney, Kavita; Thomas, Lee C; Kok, Jen; Shetty, Amith

2013-06-01

Blood pressure (BP) cuffs are potential vectors for transmission of multi-resistant organisms (MROs). The present study aims to determine MRO colonisation rates in BP cuffs from areas of high patient flow as an assessment of the quality of disinfection and infection control practices. BP cuffs in the ED, high dependency unit (HDU) and operating theatres (OT) were prospectively examined after routine disinfection procedures. Swabs collected from the inner and outer surfaces of BP cuffs during inter-patient intervals were plated onto replicate organism detection and counting, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) chromogenic agar plates to detect rates of bacterial, MRSA and VRE colonisation, respectively. High bacterial colonisation rates were detected in BP cuffs from all three areas. BP cuffs from OT were significantly less colonised compared with cuffs from HDU and ED; 76% versus 96% and 100% (P < 0.0001) for inner surfaces and 86% versus 98% and 100% (P < 0.0001) for outer surfaces, respectively. Equivalent or higher bacterial growth was observed on the inner surface compared with outer surface in 54%, 84% and 86% of BP cuffs from OT, HDU and ED, respectively. MRSA was detected in 3 of 150 (2%) swabs collected, but no VRE was detected. Although MRSA and VRE were infrequently isolated, current disinfection and infection control protocols need to be improved given the greater recovery of organisms from the inner compared with outer surfaces of BP cuffs. © 2013 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

Experiments Towards Mitigation of Motional Heating in Trapped Ion Quantum Information Processing

DTIC Science & Technology

2016-02-27

in our surface electrode trap chips. The distance-dependence measurement was taken by Deslauri- ers et al . using a 3D needle trap [9]. These results...heating rate fit for this data is shown in Figure 6-5. 68 Delay time (ms) A ve ra ge M o ti o n al O cc u p at io n al L ev el ( ) <n...Wineland. Cooling in traps. Physica Scripta, 22:216–223, 1988 . [18] W. Itano and D. Wineland. Laser cooling of ions stored in harmonic and penning traps

Nano-optical conveyor belt, part I: Theory.

PubMed

Hansen, Paul; Zheng, Yuxin; Ryan, Jason; Hesselink, Lambertus

2014-06-11

We propose a method for peristaltic transport of nanoparticles using the optical force field over a nanostructured surface. Nanostructures may be designed to produce strong near-field hot spots when illuminated. The hot spots function as optical traps, separately addressable by their resonant wavelengths and polarizations. By activating closely packed traps sequentially, nanoparticles may be handed off between adjacent traps in a peristaltic fashion. A linear repeating structure of three separately addressable traps forms a "nano-optical conveyor belt"; a unit cell with four separately addressable traps permits controlled peristaltic transport in the plane. Using specifically designed activation sequences allows particle sorting.

Ultrafast Spreading Effect Induced Rapid Cell Trapping into Porous Scaffold with Superhydrophilic Surface.

PubMed

Wang, Chenmiao; Qiao, Chunyan; Song, Wenlong; Sun, Hongchen

2015-08-19

In this contribution, superhydrophilic chitosan-based scaffolds with ultrafast spreading property were fabricated and used to improve the trapped efficiency of cells. The ultrafast spreading property allowed cells to be trapped into the internal 3D porous structures of the prepared scaffolds more quickly and effectively. Cell adhesion, growth, and proliferation were also improved, which could be attributed to the combination of UV irradiation and ultrafast spreading property. The construction of ultrafast spreading property on the scaffold surface will offer a novel way to design more effective scaffold in tissue engineering that could largely shorten the therapeutic time for patients.

Dependence of the residual surface resistance of superconducting radio frequency cavities on the cooling dynamics around T{sub c}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romanenko, A., E-mail: aroman@fnal.gov; Grassellino, A., E-mail: annag@fnal.gov; Melnychuk, O.

We report a strong effect of the cooling dynamics through T{sub c} on the amount of trapped external magnetic flux in superconducting niobium cavities. The effect is similar for fine grain and single crystal niobium and all surface treatments including electropolishing with and without 120 °C baking and nitrogen doping. Direct magnetic field measurements on the cavity walls show that the effect stems from changes in the flux trapping efficiency: slow cooling leads to almost complete flux trapping and higher residual resistance, while fast cooling leads to the much more efficient flux expulsion and lower residual resistance.

Probing surface states in PbS nanocrystal films using pentacene field effect transistors: controlling carrier concentration and charge transport in pentacene.

PubMed

Park, Byoungnam; Whitham, Kevin; Bian, Kaifu; Lim, Yee-Fun; Hanrath, Tobias

2014-12-21

We used a bilayer field effect transistor (FET) consisting of a thin PbS nanocrystals (NCs) film interfaced with vacuum-deposited pentacene to probe trap states in NCs. We interpret the observed threshold voltage shift in context of charge carrier trapping by PbS NCs and relate the magnitude of the threshold voltage shift to the number of trapped carriers. We explored a series of NC surface ligands to modify the interface between PbS NCs and pentacene and demonstrate the impact of interface chemistry on charge carrier density and the FET mobility in a pentacene FET.

Probing Intrawire, Interwire, and Diameter-Dependent Variations in Silicon Nanowire Surface Trap Density with Pump-Probe Microscopy.

PubMed

Cating, Emma E M; Pinion, Christopher W; Christesen, Joseph D; Christie, Caleb A; Grumstrup, Erik M; Cahoon, James F; Papanikolas, John M

2017-10-11

Surface trap density in silicon nanowires (NWs) plays a key role in the performance of many semiconductor NW-based devices. We use pump-probe microscopy to characterize the surface recombination dynamics on a point-by-point basis in 301 silicon NWs grown using the vapor-liquid-solid (VLS) method. The surface recombination velocity (S), a metric of the surface quality that is directly proportional to trap density, is determined by the relationship S = d/4τ from measurements of the recombination lifetime (τ) and NW diameter (d) at distinct spatial locations in individual NWs. We find that S varies by as much as 2 orders of magnitude between NWs grown at the same time but varies only by a factor of 2 or three within an individual NW. Although we find that, as expected, smaller-diameter NWs exhibit shorter τ, we also find that smaller wires exhibit higher values of S; this indicates that τ is shorter both because of the geometrical effect of smaller d and because of a poorer quality surface. These results highlight the need to consider interwire heterogeneity as well as diameter-dependent surface effects when fabricating NW-based devices.

A mechanism study of sound wave-trapping barriers.

PubMed

Yang, Cheng; Pan, Jie; Cheng, Li

2013-09-01

The performance of a sound barrier is usually degraded if a large reflecting surface is placed on the source side. A wave-trapping barrier (WTB), with its inner surface covered by wedge-shaped structures, has been proposed to confine waves within the area between the barrier and the reflecting surface, and thus improve the performance. In this paper, the deterioration in performance of a conventional sound barrier due to the reflecting surface is first explained in terms of the resonance effect of the trapped modes. At each resonance frequency, a strong and mode-controlled sound field is generated by the noise source both within and in the vicinity outside the region bounded by the sound barrier and the reflecting surface. It is found that the peak sound pressures in the barrier's shadow zone, which correspond to the minimum values in the barrier's insertion loss, are largely determined by the resonance frequencies and by the shapes and losses of the trapped modes. These peak pressures usually result in high sound intensity component impinging normal to the barrier surface near the top. The WTB can alter the sound wave diffraction at the top of the barrier if the wavelengths of the sound wave are comparable or smaller than the dimensions of the wedge. In this case, the modified barrier profile is capable of re-organizing the pressure distribution within the bounded domain and altering the acoustic properties near the top of the sound barrier.

An Ochered Fossil Marine Shell From the Mousterian of Fumane Cave, Italy

PubMed Central

Peresani, Marco; Vanhaeren, Marian; Quaggiotto, Ermanno; Queffelec, Alain; d’Errico, Francesco

2013-01-01

A scanty but varied ensemble of finds challenges the idea that Neandertal material culture was essentially static and did not include symbolic items. In this study we report on a fragmentary Miocene-Pliocene fossil marine shell, Aspa marginata , discovered in a Discoid Mousterian layer of the Fumane Cave, northern Italy, dated to at least 47.6-45.0 Cal ky BP. The shell was collected by Neandertals at a fossil exposure probably located more than 100 kms from the site. Microscopic analysis of the shell surface identifies clusters of striations on the inner lip. A dark red substance, trapped inside micropits produced by bioeroders, is interpreted as pigment that was homogeneously smeared on the outer shell surface. Dispersive X-ray and Raman analysis identify the pigment as pure hematite. Of the four hypotheses we considered to explain the presence of this object at the site, two (tool, pigment container) are discarded because in contradiction with observations. Although the other two (“manuport”, personal ornament) are both possible, we favor the hypothesis that the object was modified and suspended by a ‘thread’ for visual display as a pendant. Together with contextual and chronometric data, our results support the hypothesis that deliberate transport and coloring of an exotic object, and perhaps its use as pendant, was a component of Neandertal symbolic culture, well before the earliest appearance of the anatomically modern humans in Europe. PMID:23874677

Cell surface physiology and outer cell envelope impermeability for hydrophobic substances in Burkholderia multivorans.

PubMed

Ruskoski, Sallie A; Champlin, Franklin R

2017-07-01

The purpose of the present study was to obtain a better understanding of the relationship between cell surface physiology and outer cellular envelope permeability for hydrophobic substances in mucoid and non-mucoid B. multivorans strains, as well as in two capsule-deficient derivatives of a mucoid parental strain. Cell surface hydrophobicity properties were determined using the hydrocarbon adherence method, while outer cell envelope accessibility and permeability for non-polar compounds were measured using hydrophobic antimicrobial agent susceptibility and fluorescent probe assays. Extracellular polysaccharide (EPS) production was assessed by cultivating strains of disparate origin on yeast extract agar (YEA) containing different sugars, while the resultant colonial and cellular morphological parameters were assessed macro- and microscopically, respectively.Results/Key findings. The cell surfaces of all the strains were hydrophilic, impermeable to mechanistically disparate hydrophobic antibacterial agents and inaccessible to the hydrophobic probe N-phenyl-1-napthylamine, regardless of EPS phenotype. Supplementation of basal YEA with eight different sugars enhanced macroscopic EPS expression for all but one non-mucoid strain, with mannose potentiating the greatest effect. Despite acquisition of the mucoid phenotype, non-mucoid strains remained non-capsulated and capsulation of a hyper-mucoid strain and its two non-mucoid derivative strains was unaffected, as judged by microscopic observation. These data support the conclusion that EPS expression and the consistent mucoid phenotype are not necessarily associated with the ability of the outer cell surface to associate with non-polar substances or cellular capsulation.

Activities conducted during the definition phase of the outer planets missions program

NASA Technical Reports Server (NTRS)

1972-01-01

The activities are described of the Meteoroid Science Team for the definition phase of the outer planet missions. Studies reported include: (1) combined zodiacal experiment for the Grand Tour Missions of the outer planets, (2) optical transmission of a honeycomb panel and its effectiveness as a particle impact surface, (3) element identification data from the combined zodiacal OPGT experiment and (4) development of lightweight thermally stable mirrors.

Vacuum-isolation vessel and method for measurement of thermal noise in microphones

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J. (Inventor); Ngo, Kim Chi T. (Inventor)

1992-01-01

The vacuum isolation vessel and method in accordance with the present invention are used to accurately measure thermal noise in microphones. The apparatus and method could be used in a microphone calibration facility or any facility used for testing microphones. Thermal noise is measured to determine the minimum detectable sound pressure by the microphone. Conventional isolation apparatus and methods have been unable to provide an acoustically quiet and substantially vibration free environment for accurately measuring thermal noise. In the present invention, an isolation vessel assembly comprises a vacuum sealed outer vessel, a vacuum sealed inner vessel, and an interior suspension assembly coupled between the outer and inner vessels for suspending the inner vessel within the outer vessel. A noise measurement system records thermal noise data from the isolation vessel assembly. A vacuum system creates a vacuum between an internal surface of the outer vessel and an external surface of the inner vessel. The present invention thus provides an acoustically quiet environment due to the vacuum created between the inner and outer vessels and a substantially vibration free environment due to the suspension assembly suspending the inner vessel within the outer vessel. The thermal noise in the microphone, effectively isolated according to the invention, can be accurately measured.

Deuterium trapping in tungsten

NASA Astrophysics Data System (ADS)

Poon, Michael

Tungsten is one of the primary material candidates being investigated for use in the first-wall of a magnetic confinement fusion reactor. An ion accelerator was used to simulate the type of ion interaction that may occur at a plasma-facing material. Thermal desorption spectroscopy (TDS) was the primary tool used to analyze the effects of the irradiation. Secondary ion mass spectroscopy (SIMS) was used to determine the distribution of trapped D in the tungsten specimen. The tritium migration analysis program (TMAP) was used to simulate thermal desorption profiles from the D depth distributions. Fitting of the simulated thermal desorption profiles with the measured TDS results provided values of the D trap energies. Deuterium trapping in single crystal tungsten was studied as a function of the incident ion fluence, ion flux, irradiation temperature, irradiation history, and surface impurity levels during irradiation. The results show that deuterium was trapped at vacancies and voids. Two deuterium atoms could be trapped at a tungsten vacancy, with trapping energies of 1.4 eV and 1.2 eV for the first and second D atoms, respectively. In a tungsten void, D is trapped as atoms adsorbed on the inner walls of the void with a trap energy of 2.1 eV, or as D2 molecules inside the void with a trap energy of 1.2 eV. Deuterium trapping in polycrystalline tungsten was also studied as a function of the incident fluence, irradiation temperature, and irradiation history. Deuterium trapping in polycrystalline tungsten also occurs primarily at vacancies and voids with the same trap energies as in single crystal tungsten; however, the presence of grain boundaries promotes the formation of large surface blisters with high fluence irradiations at 500 K. In general, D trapping is greater in polycrystalline tungsten than in single crystal tungsten. To simulate mixed materials comprising of carbon (C) and tungsten, tungsten specimens were pre-irradiated with carbon ions prior to D irradiation. Deuterium trapping could be characterized by three regimes: (i) enhanced D retention in a graphitic film formed by the C+ irradiation; (ii) decreased D retention in a modified tungsten-carbon layer; and (iii) D retention in pure tungsten.

Modeling of static electrical properties in organic field-effect transistors

NASA Astrophysics Data System (ADS)

Xu, Yong; Minari, Takeo; Tsukagoshi, Kazuhito; Gwoziecki, Romain; Coppard, Romain; Benwadih, Mohamed; Chroboczek, Jan; Balestra, Francis; Ghibaudo, Gerard

2011-07-01

A modeling of organic field-effect transistors' (OFETs') electrical characteristics is presented. This model is based on a one-dimensional (1-D) Poisson's equation solution that solves the potential profile in the organic semiconducting film. Most importantly, it demonstrates that, due to the common open-surface configuration used in organic transistors, the conduction occurs in the film volume below threshold. This is because the potential at the free surface is not fixed to zero but rather rises also with the gate bias. The tail of carrier concentration at the free surface is therefore significantly modulated by the gate bias, which partially explains the gate-voltage dependent contact resistance. At the same time in the so-called subthreshold region, we observe a clear charge trapping from the difference between C-V and I-V measurements; hence a traps study by numerical simulation is also performed. By combining the analytical modeling and the traps analysis, the questions on the C-V and I-V characteristics are answered. Finally, the combined results obtained with traps fit well the experimental data in both pentacene and bis(triisopropylsilylethynyl)-pentacene OFETs.

A Surface-Coupled Optical Trap with 1-bp Precision via Active Stabilization.

PubMed

Okoniewski, Stephen R; Carter, Ashley R; Perkins, Thomas T

2017-01-01

Optical traps can measure bead motions with Å-scale precision. However, using this level of precision to infer 1-bp motion of molecular motors along DNA is difficult, since a variety of noise sources degrade instrumental stability. In this chapter, we detail how to improve instrumental stability by (1) minimizing laser pointing, mode, polarization, and intensity noise using an acousto-optical-modulator mediated feedback loop and (2) minimizing sample motion relative to the optical trap using a three-axis piezo-electric-stage mediated feedback loop. These active techniques play a critical role in achieving a surface stability of 1 Å in 3D over tens of seconds and a 1-bp stability and precision in a surface-coupled optical trap over a broad bandwidth (Δf = 0.03-2 Hz) at low force (6 pN). These active stabilization techniques can also aid other biophysical assays that would benefit from improved laser stability and/or Å-scale sample stability, such as atomic force microscopy and super-resolution imaging.

Ambient-temperature trap/release of arsenic by dielectric barrier discharge and its application to ultratrace arsenic determination in surface water followed by atomic fluorescence spectrometry

USDA-ARS?s Scientific Manuscript database

A novel dielectric barrier discharge reactor (DBDR) was utilized to trap/release arsenic coupled to hydride generation atomic fluorescence spectrometry (HGAFS). On the DBD principle, the precise and accurate control of trap/release procedures was fulfilled at ambient temperature, and an analytical m...

Evaluation of imidacloprid-treated traps as an attract and kill system for filth flies during contingency operations.

USDA-ARS?s Scientific Manuscript database

Field trials were conducted to evaluate if filth fly trap efficacy was increased by application of an insecticide to a trap’s exterior. Four Fly Terminator® Pro traps baited with Fly Terminator® attractant were suspended on PVC pipe framing at a Florida waste transfer site. Exterior surfaces of tw...

Hot gas path component trailing edge having near wall cooling features

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lacy, Benjamin Paul; Kottilingam, Srikanth Chandrudu; Miranda, Carlos Miguel

A hot gas path component includes a substrate having an outer surface and an inner surface. The inner surface defines an interior space. The outer surface defines a pressure side surface and a suction side surface. The pressure and suction side surfaces are joined together at a leading edge and at a trailing edge. A first cooling passage is formed in the suction side surface of the substrate. It is coupled in flow communication to the interior space. A second cooling passage, separate from the first cooling passage, is formed in the pressure side surface. The second cooling passage ismore » coupled in flow communication to the interior space. A cover is disposed over at least a portion of the first and second cooling passages. The interior space channels a cooling fluid to the first and second cooling passages, which channel the cooling fluid therethrough to remove heat from the component.« less

Silica nano-particle super-hydrophobic surfaces: the effects of surface morphology and trapped air pockets on hydrodynamic drainage forces.

PubMed

Chan, Derek Y C; Uddin, Md Hemayet; Cho, Kwun L; Liaw, Irving I; Lamb, Robert N; Stevens, Geoffrey W; Grieser, Franz; Dagastine, Raymond R

2009-01-01

We used atomic force microscopy to study dynamic forces between a rigid silica sphere (radius approximately 45 microm) and a silica nano-particle super-hydrophobic surface (SNP-SHS) in aqueous electrolyte, in the presence and absence of surfactant. Characterization of the SNP-SHS surface in air showed a surface roughness of up to two microns. When in contact with an aqueous phase, the SNP-SHS traps large, soft and stable air pockets in the surface interstices. The inherent roughness of the SNP-SHS together with the trapped air pockets are responsible for the superior hydrophobic properties of SNP-SHS such as high equilibrium contact angle (> 140 degrees) of water sessile drops on these surfaces and low hydrodynamic friction as observed in force measurements. We also observed that added surfactants adsorbed at the surface of air pockets magnified hydrodynamic interactions involving the SNP-SHS. The dynamic forces between the same silica sphere and a laterally smooth mica surface showed that the fitted Navier slip lengths using the Reynolds lubrication model were an order of magnitude larger than the length scale of the sphere surface roughness. The surface roughness and the lateral heterogeneity of the SNP-SHS hindered attempts to characterize the dynamic response using the Reynolds lubrication model even when augmented with a Navier slip boundary.

All-optical patterning of Au nanoparticles on surfaces using optical traps.

PubMed

Guffey, Mason J; Scherer, Norbert F

2010-11-10

The fabrication of nanoscale devices would be greatly enhanced by "nanomanipulators" that can position single and few objects rapidly with nanometer precision and without mechanical damage. Here, we demonstrate the feasibility and precision of an optical laser tweezer, or optical trap, approach to place single gold (Au) nanoparticles on surfaces with high precision (approximately 100 nm standard deviation). The error in the deposition process is rather small but is determined to be larger than the thermal fluctuations of single nanoparticles within the optical trap. Furthermore, areas of tens of square micrometers could be patterned in a matter of minutes. Since the method does not rely on lithography, scanning probes or a specialized surface, it is versatile and compatible with a variety of systems. We discuss active feedback methods to improve positioning accuracy and the potential for multiplexing and automation.

Microfabricated ion trap array

DOEpatents

Blain, Matthew G [Albuquerque, NM; Fleming, James G [Albuquerque, NM

2006-12-26

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

Determination of trap distributions from current characteristics of pentacene field-effect transistors with surface modified gate oxide

NASA Astrophysics Data System (ADS)

Scheinert, Susanne; Pernstich, Kurt P.; Batlogg, Bertram; Paasch, Gernot

2007-11-01

It has been demonstrated [K. P. Pernstich, S. Haas, D. Oberhoff, C. Goldmann, D. J. Gundlach, B. Batlogg, A. N. Rashid, and G. Schitter, J. Appl. Phys. 96, 6431 (2004)] that a controllable shift of the threshold voltage in pentacene thin film transistors is caused by the use of organosilanes with different functional groups forming a self-assembled monolayer (SAM) on the gate oxide. The observed broadening of the subthreshold region indicates that the SAM creates additional trap states. Indeed, it is well known that traps strongly influence the behavior of organic field-effect transistors (OFETs). Therefore, the so-called "amorphous silicon (a-Si) model" has been suggested to be an appropriate model to describe OFETs. The main specifics of this model are transport of carriers above a mobility edge obeying Boltzmann statistics and exponentially distributed tail states and deep trap states. Here, approximate trap distributions are determined by adjusting two-dimensional numerical simulations to the experimental data. It follows from a systematic variation of parameters describing the trap distributions that the existence of both donorlike and acceptorlike trap distributions near the valence band, respectively, and a fixed negative interface charge have to be assumed. For two typical devices with different organosilanes the electrical characteristics can be described well with a donorlike bulk trap distribution, an acceptorlike interface distribution, and/or a fixed negative interface charge. As expected, the density of the fixed or trapped interface charge depends strongly on the surface treatment of the dielectric. There are some limitations in determining the trap distributions caused by either slow time-dependent processes resulting in differences between transfer and output characteristics, or in the uncertainty of the effective mobility.

Real-Time Curvature Defect Detection on Outer Surfaces Using Best-Fit Polynomial Interpolation

PubMed Central

Golkar, Ehsan; Prabuwono, Anton Satria; Patel, Ahmed

2012-01-01

This paper presents a novel, real-time defect detection system, based on a best-fit polynomial interpolation, that inspects the conditions of outer surfaces. The defect detection system is an enhanced feature extraction method that employs this technique to inspect the flatness, waviness, blob, and curvature faults of these surfaces. The proposed method has been performed, tested, and validated on numerous pipes and ceramic tiles. The results illustrate that the physical defects such as abnormal, popped-up blobs are recognized completely, and that flames, waviness, and curvature faults are detected simultaneously. PMID:23202186

Space Shuttle Orbiter Digital Outer Mold Line Scanning

NASA Technical Reports Server (NTRS)

Campbell, Charles H.; Wilson, Brad; Pavek, Mike; Berger, Karen

2012-01-01

The Space Shuttle Orbiters Discovery and Endeavor have been digitally scanned to produce post-flight configuration outer mold line surfaces. Very detailed scans of the windward side of these vehicles provide resolution of the detailed tile step and gap geometry, as well as the reinforced carbon carbon nose cap and leading edges. Lower resolution scans of the upper surface provide definition of the crew cabin windows, wing upper surfaces, payload bay doors, orbital maneuvering system pods and the vertical tail. The process for acquisition of these digital scans as well as post-processing of the very large data set will be described.

Efficacy of multifunnel traps for capturing emerald ash borer (Coleoptera: Buprestidae): effect of color, glue, and other trap coatings.

PubMed

Francese, Joseph A; Fraser, Ivich; Lance, David R; Mastro, Victor C

2011-06-01

Tens of thousands of adhesive-coated purple prism traps are deployed annually in the United States to survey for the invasive emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). A reusable, more user-friendly trap is desired by program managers, surveyors, and researchers. Field assays were conducted in southeastern Michigan to ascertain the feasibility of using nonsticky traps as survey and detection tools for emerald ash borer. Three nonsticky trap designs, including multifunnel (Lindgren), modified intercept panel, and drainpipe (all painted purple) were compared with the standard purple prism trap; no statistical differences in capture of emerald ash borer adults were detected between the multifunnel design and the prism. In subsequent color comparison assays, both green- and purple-painted multifunnel traps (and later, plastic versions of these colors) performed as well or better than the prism traps. Multifunnel traps coated with spray-on adhesive caught more beetles than untreated traps. The increased catch, however, occurred in the traps' collection cups and not on the trap surface. In a separate assay, there was no significant difference detected between glue-coated traps and Rain-X (normally a glass treatment)-coated traps, but both caught significantly more A. planipennis adults than untreated traps.

Winter frost at Viking Lander 2 site

NASA Technical Reports Server (NTRS)

Svitek, Thomas; Murray, Bruce

1990-01-01

This paper presents quantitative evidence for cold trapping (frost redeposition) at the Viking Lander 2 site. This evidence consists of the frost surface coverage and color transition, the timing of this transition, and the limited vertical mixing and horizontal water transport. It is argued that cold trapping must be a general property of seasonal frost and, therefore, must be considered in order to understand the evolution of the surface environment of Mars.

Non-uniformly functionalized titanium carbide-based MXenes as an anchoring material for Li-S batteries: A first-principles calculation

NASA Astrophysics Data System (ADS)

Sim, Eun Seob; Chung, Yong-Chae

2018-03-01

In this study, the influence of the non-uniform surface of F- and O-functionalized Ti2C on the anchoring behavior of lithium polysulfide (LiPS) is investigated using density functional theory. In order to consider the non-uniform surface, the substitutional, vacancy, and S-trapped sites of F- and O-functionalized Ti2C are designed. The anchoring behavior is investigated considering the adsorption energy of LiPS, reactivity between Li atoms and the substrate, and the reduction state of the S atoms. On the F-substitutional site of the O-functionalized surface, it is confirmed that the suppressing mechanism changes from the neutralization of S atoms to the anchoring of LiPS. However, too strong of an interaction between Ti atoms exposed at the vacancy site and S atoms induces trapping of the S atom at the vacancies of both F- and O-functionalized surfaces. As a result of the trapping of the S atom, the use of active material decreases. In addition, the S-trapped site originated from the vacancy site does not affect the suppressing mechanism. In conclusion, to optimize the Ti2C-based MXene as an anchoring material for Li-S batteries, the preparation process should be focused on eliminating the vacancy of functional groups.

Molecular adsorption steers bacterial swimming at the air/water interface.

PubMed

Morse, Michael; Huang, Athena; Li, Guanglai; Maxey, Martin R; Tang, Jay X

2013-07-02

Microbes inhabiting Earth have adapted to diverse environments of water, air, soil, and often at the interfaces of multiple media. In this study, we focus on the behavior of Caulobacter crescentus, a singly flagellated bacterium, at the air/water interface. Forward swimming C. crescentus swarmer cells tend to get physically trapped at the surface when swimming in nutrient-rich growth medium but not in minimal salt motility medium. Trapped cells move in tight, clockwise circles when viewed from the air with slightly reduced speed. Trace amounts of Triton X100, a nonionic surfactant, release the trapped cells from these circular trajectories. We show, by tracing the motion of positively charged colloidal beads near the interface that organic molecules in the growth medium adsorb at the interface, creating a high viscosity film. Consequently, the air/water interface no longer acts as a free surface and forward swimming cells become hydrodynamically trapped. Added surfactants efficiently partition to the surface, replacing the viscous layer of molecules and reestablishing free surface behavior. These findings help explain recent similar studies on Escherichia coli, showing trajectories of variable handedness depending on media chemistry. The consistent behavior of these two distinct microbial species provides insights on how microbes have evolved to cope with challenging interfacial environments. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

On the physics of dispersive electron transport characteristics in SnO2 nanoparticle-based dye sensitized solar cells.

PubMed

Ashok, Aditya; Vijayaraghavan, S N; Unni, Gautam E; Nair, Shantikumar V; Shanmugam, Mariyappan

2018-04-27

The present study elucidates dispersive electron transport mediated by surface states in tin oxide (SnO 2 ) nanoparticle-based dye sensitized solar cells (DSSCs). Transmission electron microscopic studies on SnO 2 show a distribution of ∼10 nm particles exhibiting (111) crystal planes with inter-planar spacing of 0.28 nm. The dispersive transport, experienced by photo-generated charge carriers in the bulk of SnO 2 , is observed to be imposed by trapping and de-trapping processes via SnO 2 surface states present close to the band edge. The DSSC exhibits 50% difference in performance observed between the forward (4%) and reverse (6%) scans due to the dispersive transport characteristics of the charge carriers in the bulk of the SnO 2 . The photo-generated charge carriers are captured and released by the SnO 2 surface states that are close to the conduction band-edge resulting in a very significant variation; this is confirmed by the hysteresis observed in the forward and reverse scan current-voltage measurements under AM1.5 illumination. The hysteresis behavior assures that the charge carriers are accumulated in the bulk of electron acceptor due to the trapping, and released by de-trapping mediated by surface states observed during the forward and reverse scan measurements.

On the physics of dispersive electron transport characteristics in SnO2 nanoparticle-based dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Ashok, Aditya; Vijayaraghavan, S. N.; Unni, Gautam E.; Nair, Shantikumar V.; Shanmugam, Mariyappan

2018-04-01

The present study elucidates dispersive electron transport mediated by surface states in tin oxide (SnO2) nanoparticle-based dye sensitized solar cells (DSSCs). Transmission electron microscopic studies on SnO2 show a distribution of ˜10 nm particles exhibiting (111) crystal planes with inter-planar spacing of 0.28 nm. The dispersive transport, experienced by photo-generated charge carriers in the bulk of SnO2, is observed to be imposed by trapping and de-trapping processes via SnO2 surface states present close to the band edge. The DSSC exhibits 50% difference in performance observed between the forward (4%) and reverse (6%) scans due to the dispersive transport characteristics of the charge carriers in the bulk of the SnO2. The photo-generated charge carriers are captured and released by the SnO2 surface states that are close to the conduction band-edge resulting in a very significant variation; this is confirmed by the hysteresis observed in the forward and reverse scan current-voltage measurements under AM1.5 illumination. The hysteresis behavior assures that the charge carriers are accumulated in the bulk of electron acceptor due to the trapping, and released by de-trapping mediated by surface states observed during the forward and reverse scan measurements.

Colloid labelled with radionuclide and method

DOEpatents

Atcher, R.W.; Hines, J.J.

1990-11-13

A ferric hydroxide colloid having an alpha-emitting radionuclide essentially on the outer surfaces and a method of forming same. The method includes oxidizing a ferrous hydroxide to ferric hydroxide in the presence of a preselected radionuclide to form a colloid having the radionuclide on the outer surface thereof, and thereafter washing the colloid, and suspending the washed colloid in a suitable solution. The labelled colloid is useful in cancer therapy and for the treatment of inflamed joints. No Drawings

Method of making colloid labeled with radionuclide

DOEpatents

Atcher, Robert W.; Hines, John J.

1991-01-01

A ferric hydroxide colloid having an alpha-emitting radionuclide essentially on the outer surfaces and a method of forming same. The method includes oxidizing a ferrous hydroxide to ferric hydroxide in the presence of a preselected radionuclide to form a colloid having the radionuclide on the outer surface thereof, and thereafter washing the colloid, and suspending the washed colloid in a suitable solution. The labelled colloid is useful in cancer therapy and for the treatment of inflamed joints.

Colloid labelled with radionuclide and method

DOEpatents

Atcher, Robert W.; Hines, John J.

1990-01-01

A ferric hydroxide colloid having an alpha-emitting radionuclide essentially on the outer surfaces and a method of forming same. The method includes oxidizing a ferrous hydroxide to ferric hydroxide in the presence of a preselected radionuclide to form a colloid having the radionuclide on the outer surface thereof, and thereafter washing the colloid, and suspending the washed colloid in a suitable solution. The labelled colloid is useful in cancer therapy and for the treatment of inflamed joints.

Periplasmic orientation of nascent lipid A in the inner membrane of an Escherichia coli LptA mutant

PubMed Central

Ma, Bing; Reynolds, C. Michael; Raetz, Christian R. H.

2008-01-01

The core-lipid A domain of Escherichia coli lipopolysaccharide (LPS) is synthesized on the inner surface of the inner membrane (IM) and flipped to its outer surface by the ABC transporter MsbA. Recent studies with deletion mutants implicate the periplasmic protein LptA, the cytosolic protein LptB, and the IM proteins LptC, LptF, and LptG in the subsequent transport of nascent LPS to the outer membrane (OM), where the LptD/LptE complex flips LPS to the outer surface. We have isolated a temperature-sensitive mutant (MB1) harboring the S22C and Q111P substitutions in LptA. MB1 stops growing after 30 min at 42°C. 32Pi and [35S]methionine labeling show that export of newly synthesized phospholipids and proteins is not severely impaired, but export of LPS is defective. Using the lipid A 1-phosphatase LpxE as a periplasmic IM marker and the lipid A 3-O-deacylase PagL as an OM marker, we show that core-lipid A reaches the periplasmic side of the IM at 42°C in MB1 but not the outer surface of the OM. Electron microscopy of MB1 reveals dense periplasmic material and a smooth OM at 42°C, consistent with a role for LptA in shuttling LPS across the periplasm. PMID:18768814

Periplasmic orientation of nascent lipid A in the inner membrane of an Escherichia coli LptA mutant.

PubMed

Ma, Bing; Reynolds, C Michael; Raetz, Christian R H

2008-09-16

The core-lipid A domain of Escherichia coli lipopolysaccharide (LPS) is synthesized on the inner surface of the inner membrane (IM) and flipped to its outer surface by the ABC transporter MsbA. Recent studies with deletion mutants implicate the periplasmic protein LptA, the cytosolic protein LptB, and the IM proteins LptC, LptF, and LptG in the subsequent transport of nascent LPS to the outer membrane (OM), where the LptD/LptE complex flips LPS to the outer surface. We have isolated a temperature-sensitive mutant (MB1) harboring the S22C and Q111P substitutions in LptA. MB1 stops growing after 30 min at 42 degrees C. (32)P(i) and [(35)S]methionine labeling show that export of newly synthesized phospholipids and proteins is not severely impaired, but export of LPS is defective. Using the lipid A 1-phosphatase LpxE as a periplasmic IM marker and the lipid A 3-O-deacylase PagL as an OM marker, we show that core-lipid A reaches the periplasmic side of the IM at 42 degrees C in MB1 but not the outer surface of the OM. Electron microscopy of MB1 reveals dense periplasmic material and a smooth OM at 42 degrees C, consistent with a role for LptA in shuttling LPS across the periplasm.

Behaviour of wrapped cold-formed steel columns under different loading conditions

NASA Astrophysics Data System (ADS)

Baabu, B. Hari; Sreenath, S.

2017-07-01

The use of Cold Formed Steel (CFS) sections as structural members is widely accepted because of its light nature. However, the load carrying capacity of these sections will be less compared to hot rolled sections. This study is meant to analyze the possibility of strengthening cold formed members by wrapping it with Glass Fiber Reinforced Polymer (GFRP) laminates. Light gauge steel columns of cross sectional dimensions 100mm x 50mm x 3.15mm were taken for this study. The effective length of the section is about 750mm. A total of 8 specimens including the control specimen is tested under axial and eccentric loading. The columns were tested keeping both ends hinged. For both loading cases the buckling behaviour, ultimate load carrying capacity and load-deflection characteristics of the CFS columns were analyzed. The GFRP laminates were wrapped on columns in three different ways such that wrapping the outer surface of web and flange throughout the length of specimen, wrapping the outer surface of web alone throughout the length of specimen and wrapping the outer surface of web and flange for the upper half length of the specimen where the buckling is expected. For both loading cases, the results indicated that the column with wrapping at the outer surface of web and flange throughout the length of specimen provides better strength for it.

Jupiter plasma wave observations: an initial voyager 1 overview.

PubMed

Scarf, F L; Gurnett, D A; Kurth, W S

1979-06-01

The Voyager I plasma wave instrument detected low-frequency radio emissions, ion acoustic waves, and electron plasma oscillations for a period of months before encountering Jupiter's bow shock. In the outer magnetosphere, measurements of trapped radio waves were used to derive an electron density profile. Near and within the Io plasma torus the instrument detected high-frequency electrostatic waves, strong whistler mode turbulence, and discrete whistlers, apparently associated with lightning. Some strong emissions in the tail region and some impulsive signals have not yet been positively identified.

Textured-surface quartz resonator fluid density and viscosity monitor

DOEpatents

Martin, Stephen J.; Wiczer, James J.; Cernosek, Richard W.; Frye, Gregory C.; Gebert, Charles T.; Casaus, Leonard; Mitchell, Mary A.

1998-08-25

A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.

Ferrules seals

DOEpatents

Smith, James L.

1984-01-01

A device is provided for sealing an inner tube and an outer tube without excessively deforming the tubes. The device includes two ferrules which cooperate to form a vacuum-tight seal between the inner tube and outer tube and having mating surfaces such that overtightening is not possible.

Nodulation outer proteins: double-edged swords of symbiotic rhizobia

USDA-ARS?s Scientific Manuscript database

Rhizobia are nitrogen-fixing bacteria that establish a nodule symbiosis with legumes. Nodule formation is the result of a complex bacterial infection process, which depends on signals and surface determinants produced by both symbiotic partners. Among them, rhizobial nodulation outer proteins (Nops)...

Immobilization of single argon atoms in nano-cages of two-dimensional zeolite model systems.

PubMed

Zhong, Jian-Qiang; Wang, Mengen; Akter, Nusnin; Kestell, John D; Boscoboinik, Alejandro M; Kim, Taejin; Stacchiola, Dario J; Lu, Deyu; Boscoboinik, J Anibal

2017-07-17

The confinement of noble gases on nanostructured surfaces, in contrast to bulk materials, at non-cryogenic temperatures represents a formidable challenge. In this work, individual Ar atoms are trapped at 300 K in nano-cages consisting of (alumino)silicate hexagonal prisms forming a two-dimensional array on a planar surface. The trapping of Ar atoms is detected in situ using synchrotron-based ambient pressure X-ray photoelectron spectroscopy. The atoms remain in the cages upon heating to 400 K. The trapping and release of Ar is studied combining surface science methods and density functional theory calculations. While the frameworks stay intact with the inclusion of Ar atoms, the permeability of gasses (for example, CO) through them is significantly affected, making these structures also interesting candidates for tunable atomic and molecular sieves. These findings enable the study of individually confined noble gas atoms using surface science methods, opening up new opportunities for fundamental research.

Immobilization of single argon atoms in nano-cages of two-dimensional zeolite model systems

DOE PAGES

Zhong, Jian-Qiang; Wang, Mengen; Akter, Nusnin; ...

2017-07-17

The confinement of noble gases on nanostructured surfaces, in contrast to bulk materials, at non-cryogenic temperatures represents a formidable challenge. Here, individual Ar atoms are trapped at 300 K in nano-cages consisting of (alumino)silicate hexagonal prisms forming a two-dimensional array on a planar surface. The trapping of Ar atoms is detected in situ using synchrotron-based ambient pressure X-ray photoelectron spectroscopy. The atoms remain in the cages upon heating to 400 K. The trapping and release of Ar is studied combining surface science methods and density functional theory calculations. While the frameworks stay intact with the inclusion of Ar atoms, themore » permeability of gasses (for example, CO) through them is significantly affected, making these structures also interesting candidates for tunable atomic and molecular sieves. Our findings enable the study of individually confined noble gas atoms using surface science methods, opening up new opportunities for fundamental research.« less

Enhanced light trapping by focused ion beam (FIB) induced self-organized nanoripples on germanium (100) surface

NASA Astrophysics Data System (ADS)

Kamaliya, Bhaveshkumar; Mote, Rakesh G.; Aslam, Mohammed; Fu, Jing

2018-03-01

In this paper, we demonstrate enhanced light trapping by self-organized nanoripples on the germanium surface. The enhanced light trapping leading to high absorption of light is confirmed by the experimental studies as well as the numerical simulations using the finite-difference time-domain method. We used gallium ion (Ga+) focused ion beam to enable the formation of the self-organized nanoripples on the germanium (100) surface. During the fabrication, the overlap of the scanning beam is varied from zero to negative value and found to influence the orientation of the nanoripples. Evolution of nanostructures with the variation of beam overlap is investigated. Parallel, perpendicular, and randomly aligned nanoripples with respect to the scanning direction are obtained via manipulation of the scanning beam overlap. 95% broadband absorptance is measured in the visible electromagnetic region for the nanorippled germanium surface. The reported light absorption enhancement can significantly improve the efficiency of germanium-silicon based photovoltaic systems.

Immobilization of single argon atoms in nano-cages of two-dimensional zeolite model systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong, Jian-Qiang; Wang, Mengen; Akter, Nusnin

The confinement of noble gases on nanostructured surfaces, in contrast to bulk materials, at non-cryogenic temperatures represents a formidable challenge. Here, individual Ar atoms are trapped at 300 K in nano-cages consisting of (alumino)silicate hexagonal prisms forming a two-dimensional array on a planar surface. The trapping of Ar atoms is detected in situ using synchrotron-based ambient pressure X-ray photoelectron spectroscopy. The atoms remain in the cages upon heating to 400 K. The trapping and release of Ar is studied combining surface science methods and density functional theory calculations. While the frameworks stay intact with the inclusion of Ar atoms, themore » permeability of gasses (for example, CO) through them is significantly affected, making these structures also interesting candidates for tunable atomic and molecular sieves. Our findings enable the study of individually confined noble gas atoms using surface science methods, opening up new opportunities for fundamental research.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Moonsoo; Kim, Jongmin; Cho, Jaehee

Graphical abstract: The presence of Chlorine in the outer surface resulted in a highly electro-negative surface states and an increase in the vacuum energy level. - Highlights: • We investigated the influence of chlorine surface treatment on ITO properties. • Chlorination induced the change of the electro-static potential in the outer surface. • Chlorine electro-chemical treatment of ITO is a simple, fast and effective technique. - Abstract: In this work, we investigate the influence of a chlorine-based electro-chemical surface treatment on the characteristics of indium tin oxide (ITO) including the work function, chemical composition, and phase transition. The treated ITOsmore » were characterized using X-ray photoelectron spectroscopy (XPS), ultra-violet photoelectron spectroscopy (UPS), 4-point probe measurements, and grazing incidence X-ray diffraction (GI-XRD). We confirmed a change of the chemical composition in the near-surface region of the ITO and the formation of indium-chlorine (In-Cl) bonds and surface dipoles (via XPS). In particular, the change of the electro-static potential in the outer surface was caused by chlorination. Due to the vacuum-level shift after the electro-chemical treatment in a dilute hydrochloric acid, the ITO work function was increased by ∼0.43 eV (via UPS); furthermore, the electro-negativity of the chlorine anions attracted electrons to emit them from the hole transport layer (HTL) to the ITO anodes, resulting in an increase of the hole-injection efficiency.« less

Modeling CO2-Water-Mineral Wettability and Mineralization for Carbon Geosequestration.

PubMed

Liang, Yunfeng; Tsuji, Shinya; Jia, Jihui; Tsuji, Takeshi; Matsuoka, Toshifumi

2017-07-18

Carbon dioxide (CO 2 ) capture and storage (CCS) is an important climate change mitigation option along with improved energy efficiency, renewable energy, and nuclear energy. CO 2 geosequestration, that is, to store CO 2 under the subsurface of Earth, is feasible because the world's sedimentary basins have high capacity and are often located in the same region of the world as emission sources. How CO 2 interacts with the connate water and minerals is the focus of this Account. There are four trapping mechanisms that keep CO 2 in the pores of subsurface rocks: (1) structural trapping, (2) residual trapping, (3) dissolution trapping, and (4) mineral trapping. The first two are dominated by capillary action, where wettability controls CO 2 and water two-phase flow in porous media. We review state-of-the-art studies on CO 2 /water/mineral wettability, which was found to depend on pressure and temperature conditions, salt concentration in aqueous solutions, mineral surface chemistry, and geometry. We then review some recent advances in mineral trapping. First, we show that it is possible to reproduce the CO 2 /water/mineral wettability at a wide range of pressures using molecular dynamics (MD) simulations. As the pressure increases, CO 2 gas transforms into a supercritical fluid or liquid at ∼7.4 MPa depending on the environmental temperature. This transition leads to a substantial decrease of the interfacial tension between CO 2 and reservoir brine (or pure water). However, the wettability of CO 2 /water/rock systems depends on the type of rock surface. Recently, we investigated the contact angle of CO 2 /water/silica systems with two different silica surfaces using MD simulations. We found that contact angle increased with pressure for the hydrophobic (siloxane) surface while it was almost constant for the hydrophilic (silanol) surface, in excellent agreement with experimental observations. Furthermore, we found that the CO 2 thin films at the CO 2 -hydrophilic silica and CO 2 -H 2 O interfaces displayed a linear correlation, which can in turn explain the constant contact angle on the hydrophilic silica surface. In view of the literature and our study results, a few recommendations seem necessary to construct a molecular system suitable to study wettability with MD simulations. Future work should be conducted to determine the influence of brine salinity on the wettability of minerals with high cation exchange capacity. Mineral trapping is believed to be an extremely slow process, likely taking thousands of years. However, a recent pilot study demonstrated that CO 2 mineralization occurs within 2 years in highly reactive basalt reservoirs. A first-principles MD study has also shown that carbonation reactions occur rapidly at the surface oxygen sites of a reactive mineral. We observed carbonate ions on both a newly cleaved quartz surface (without hydrolysis), and a basalt andesine surface after hydrolysis in a CO 2 -rich environment. Future work should consider the influence of water, gas impurities, and mineral cation type on carbonation.

Surface plasmon-mediated energy transfer of electrically-pumped excitons

DOEpatents

An, Kwang Hyup; Shtein, Max; Pipe, Kevin P.

2015-08-25

An electrically pumped light emitting device emits a light when powered by a power source. The light emitting device includes a first electrode, a second electrode including an outer surface, and at least one active organic semiconductor disposed between the first and second electrodes. The device also includes a dye adjacent the outer surface of the second electrode such that the second electrode is disposed between the dye and the active organic semiconductor. A voltage applied by the power source across the first and second electrodes causes energy to couple from decaying dipoles into surface plasmon polariton modes, which then evanescently couple to the dye to cause the light to be emitted.

Reversible gating of smart plasmonic molecular traps using thermoresponsive polymers for single-molecule detection

PubMed Central

Zheng, Yuanhui; Soeriyadi, Alexander H.; Rosa, Lorenzo; Ng, Soon Hock; Bach, Udo; Justin Gooding, J.

2015-01-01

Single-molecule surface-enhanced Raman spectroscopy (SERS) has attracted increasing interest for chemical and biochemical sensing. Many conventional substrates have a broad distribution of SERS enhancements, which compromise reproducibility and result in slow response times for single-molecule detection. Here we report a smart plasmonic sensor that can reversibly trap a single molecule at hotspots for rapid single-molecule detection. The sensor was fabricated through electrostatic self-assembly of gold nanoparticles onto a gold/silica-coated silicon substrate, producing a high yield of uniformly distributed hotspots on the surface. The hotspots were isolated with a monolayer of a thermoresponsive polymer (poly(N-isopropylacrylamide)), which act as gates for molecular trapping at the hotspots. The sensor shows not only a good SERS reproducibility but also a capability to repetitively trap and release molecules for single-molecular sensing. The single-molecule sensitivity is experimentally verified using SERS spectral blinking and bianalyte methods. PMID:26549539

Importance of hydrophobic traps for proton diffusion in lyotropic liquid crystals

DOE PAGES

McDaniel, Jesse G.; Yethiraj, Arun

2016-03-04

The diffusion of protons in self-assembled systems is potentially important for the design of efficient proton exchange membranes. In this work, we study proton dynamics in a low-water content, lamellar phase of an sodium-carboxylate gemini surfactant/water system using computer simulations. The hopping of protons via the Grotthuss mechanism is explicity allowed through the multi-state empirical valence bond (MS-EVB) method. We find that the hydronium ion is trapped on the hydrophobic side of the surfactant-water interface, and proton diffusion then proceeds by hopping between surface sites. The importance of hydrophobic traps is surprising, because one would expect the hydronium ions tomore » be trapped at the charged head-groups. Finally, the physics illustrated in this system should be relevant to the proton dynamics in other amphiphilic membrane systems, whenever there exists exposed hydrophobic surface regions.« less

A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters

NASA Astrophysics Data System (ADS)

Muñoz, Ricardo R.; Côté, Patrick; Santana, Felipe A.; Geha, Marla; Simon, Joshua D.; Oyarzún, Grecco A.; Stetson, Peter B.; Djorgovski, S. G.

2018-06-01

We present structural parameters from a wide-field homogeneous imaging survey of Milky Way satellites carried out with the MegaCam imagers on the 3.6 m Canada–France–Hawaii Telescope and 6.5 m Magellan-Clay telescope. Our survey targets an unbiased sample of “outer halo” satellites (i.e., substructures having galactocentric distances greater than 25 kpc) and includes classical dSph galaxies, ultra-faint dwarfs, and remote globular clusters. We combine deep, panoramic gr imaging for 44 satellites and archival gr imaging for 14 additional objects (primarily obtained with the DECam instrument as part of the Dark Energy Survey) to measure photometric and structural parameters for 58 outer halo satellites. This is the largest and most uniform analysis of Milky Way satellites undertaken to date and represents roughly three-quarters (58/81 ≃ 72%) of all known outer halo satellites. We use a maximum-likelihood method to fit four density laws to each object in our survey: exponential, Plummer, King, and Sérsic models. We systematically examine the isodensity contour maps and color–magnitude diagrams for each of our program objects, present a comparison with previous results, and tabulate our best-fit photometric and structural parameters, including ellipticities, position angles, effective radii, Sérsic indices, absolute magnitudes, and surface brightness measurements. We investigate the distribution of outer halo satellites in the size–magnitude diagram and show that the current sample of outer halo substructures spans a wide range in effective radius, luminosity, and surface brightness, with little evidence for a clean separation into star cluster and galaxy populations at the faintest luminosities and surface brightnesses.

On the sputter alteration of regoliths of outer solar system bodies

NASA Technical Reports Server (NTRS)

Hapke, Bruce

1987-01-01

Several processes that are expected to occur when the porous regoliths of outer solar system bodies (without atmospheres) are subjected to energetic ion bombardment are discussed. The conclusions reached in much of the literature addressing sputtering are quantitatively or qualitatively incorrect because effects of soil porosity have been neglected. It is shown theoretically and experimentally that porosity reduces the effective sputtering yield of a soil by more than an order of magnitude. Between 90 and 97% of the sputtered atoms are trapped within the regolith, where they are factionated by differential desorption. Experiments indicate that more volatile species have higher desorption probabilities. This process is the most important way in which alteration of chemical and optical properties occurs when a regolith is sputtered. When a basic silicate soil is irradiated these effects lead to sputter-deposited films enriched in metallic iron, while O, Na and K are preferentially lost. The Na and K are present in the atmosphere above the sputtered silicate in quantities much greater than their abundances in the regolith. Icy regoliths of SO2 should be enriched in elemental S and/or S2O. This prediction is supported by the probable identification of S2O and polysulfur oxide bands in the IR spectra of H-sputtered SO2 reported by Moore. When porous mixtures of water, ammonia and methane frosts are sputtered, the loss of H and surface reactions of C, N and O in the deposits should produce complex hydrocarbons and carbohydrates, some of which may be quite dark. Such reactions may have played a role in the formation of the matrix material of carbonaceous chondrites prior to agglomeration.

The structure of and origin of nodular chromite from the Troodos ophiolite, Cyprus, revealed using high-resolution X-ray computed tomography and electron backscatter diffraction

NASA Astrophysics Data System (ADS)

Prichard, H. M.; Barnes, S. J.; Godel, B.; Reddy, S. M.; Vukmanovic, Z.; Halfpenny, A.; Neary, C. R.; Fisher, P. C.

2015-03-01

Nodular chromite is a characteristic feature of ophiolitic podiform chromitite and there has been much debate about how it forms. Nodular chromite from the Troodos ophiolite in Cyprus is unusual in that it contains skeletal crystals enclosed within the centres of the nodules and interstitial to them. 3D imaging and electron backscatter diffraction have shown that the skeletal crystals within the nodules are single crystals that are surrounded by a rim of polycrystalline chromite. 3D analysis reveals that the skeletal crystals are partially or completely formed cage or hopper structures elongated along the < 111 > axis. The rim is composed of a patchwork of chromite grains that are truncated on the outer edge of the rim. The skeletal crystals formed first from a magma supersaturated in chromite and silicate minerals crystallised from melt trapped between the chromite skeletal crystal blades as they grew. The formation of skeletal crystals was followed by a crystallisation event which formed a silicate-poor rim of chromite grains around the skeletal crystals. These crystals show a weak preferred orientation related to the orientation of the core skeletal crystal implying that they formed by nucleation and growth on this core, and did not form by random mechanical aggregation. Patches of equilibrium adcumulate textures within the rim attest to in situ development of such textures. The nodules were subsequently exposed to chromite undersaturated magma resulting in dissolution, recorded by truncated grain boundaries in the rim and a smooth outer surface to the nodule. None of these stages of formation require a turbulent magma. Lastly the nodules impinged on each other causing local deformation at points of contact.

COLD TRAPS

DOEpatents

Thompson, W.I.

1958-09-30

A cold trap is presented for removing a condensable component from a gas mixture by cooling. It consists of a shell, the exterior surface of which is chilled by a refrigerant, and conductive fins welded inside the shell to condense the gas, and distribute the condensate evenly throughout the length of the trap, so that the trap may function until it becomes completely filled with the condensed solid. The contents may then be removed as either a gas or as a liquid by heating the trap. This device has particuinr use as a means for removing uranium hexafluoride from the gaseous diffusion separation process during equipment breakdown and repair periods.

Freeze-fracture studies of photoreceptor membranes: new observations bearing upon the distribution of cholesterol

PubMed Central

1983-01-01

We performed electron microscopy of replicas from freeze-fractured retinas exposed during or after fixation to the cholesterol-binding antibiotic, filipin. We observed characteristic filipin-induced perturbations throughout the disk and plasma membranes of retinal rod outer segments of various species. It is evident that a prolonged exposure to filipin in fixative enhances rather than reduces presumptive cholesterol detection in the vertebrate photoreceptor cell. In agreement with the pattern seen in our previous study (Andrews, L.D., and A. I. Cohen, 1979, J. Cell Biol., 81:215-228), filipin- binding in membranes exhibiting particle-free patches seemed largely confined to these patches. Favorably fractured photoreceptors exhibited marked filipin-binding in apical inner segment plasma membrane topologically confluent with and proximate to the outer segment plasma membrane, which was comparatively free of filipin binding. A possible boundary between these differing membrane domains was suggested in a number of replicas exhibiting lower filipin binding to the apical plasma membrane of the inner segment in the area surrounding the cilium. This area contains a structure (Andrews, L. D., 1982, Freeze- fracture studies of vertebrate photoreceptors, In Structure of the Eye, J. G. Hollyfield and E. Acosta Vidrio, editors, Elsevier/North-Holland, New York, 11-23) that resembles the active zones of the nerve terminals for the frog neuromuscular junction. These observations lead us to hypothesize that these structures may function to direct vesicle fusion to occur near them, in a domain of membrane more closely resembling outer than inner segment plasma membrane. The above evidence supports the views that (a) all disk membranes contain cholesterol, but the particle-free patches present in some disks trap cholesterol from contiguous particulate membrane regions; (b) contiguous inner and outer segment membranes may greatly differ in cholesterol content; and (c) the suggested higher cholesterol in the inner segment than in the outer segment plasma membrane may help direct newly inserted photopigment molecules to the outer segment. PMID:6411740

Observation of the Amorphous-to-Crystalline Surface Transition in Al-AlxOy Using Slow Positrons

NASA Astrophysics Data System (ADS)

Lynn, K. G.

1980-05-01

The amorphous-to-crystalline surface transition of AlxOy on the Al(111) surface is observed between 650 and 800 K with different O2 exposures by measuring the positronium (Ps) fraction produced by e+ impinging on the surface. The data are interpreted in terms of vacancy-type defects in the film or at the metal-metal-oxide interface which as trapping sites for e+ or Ps. As the ordering process proceeds to completion the trapping centers anneal out and the Ps fraction increases, showing an irreversible transition. This technique provides a new experimental method to study interfaces.

Vertical plasmonic nanowires for 3D nanoparticle trapping

NASA Astrophysics Data System (ADS)

Wu, Jingzhi; Gan, Xiaosong

2011-12-01

Nanoparticle trapping is considered to be more challenging than trapping micron-sized objects because of the diffraction limit of light and the severe Brownian motion of the nanoparticles. We introduce a nanoparticle trapping approach based on plasmonic nanostructures, which consist of nanopillars with high aspect ratio. The plasmonic nanopillars behave as plasmonic resonators that rely on paired nano-pillars supporting gap plasmon modes. The localized surface plasmon resonance effect provides strong electromagnetic field enhancement and enables confinement of nanoparticles in three dimensional space. Numerical simulations indicate that the plasmonic structure provides stronger optical forces for trapping nanoparticles. The study of thermal effect of the plasmonic structure shows that the impact of the thermal force is significant, which may determine the outcome of the nanoparticle trapping.

The Heterogeneity and Spatial Patterning of Structure and Physiology across the Leaf Surface in Giant Leaves of Alocasia macrorrhiza

PubMed Central

Li, Shuai; Zhang, Yong-Jiang; Sack, Lawren; Scoffoni, Christine; Ishida, Atsushi; Chen, Ya-Jun; Cao, Kun-Fang

2013-01-01

Leaf physiology determines the carbon acquisition of the whole plant, but there can be considerable variation in physiology and carbon acquisition within individual leaves. Alocasia macrorrhiza (L.) Schott is an herbaceous species that can develop very large leaves of up to 1 m in length. However, little is known about the hydraulic and photosynthetic design of such giant leaves. Based on previous studies of smaller leaves, and on the greater surface area for trait variation in large leaves, we hypothesized that A. macrorrhiza leaves would exhibit significant heterogeneity in structure and function. We found evidence of reduced hydraulic supply and demand in the outer leaf regions; leaf mass per area, chlorophyll concentration, and guard cell length decreased, as did stomatal conductance, net photosynthetic rate and quantum efficiency of photosystem II. This heterogeneity in physiology was opposite to that expected from a thinner boundary layer at the leaf edge, which would have led to greater rates of gas exchange. Leaf temperature was 8.8°C higher in the outer than in the central region in the afternoon, consistent with reduced stomatal conductance and transpiration caused by a hydraulic limitation to the outer lamina. The reduced stomatal conductance in the outer regions would explain the observed homogeneous distribution of leaf water potential across the leaf surface. These findings indicate substantial heterogeneity in gas exchange across the leaf surface in large leaves, greater than that reported for smaller-leafed species, though the observed structural differences across the lamina were within the range reported for smaller-leafed species. Future work will determine whether the challenge of transporting water to the outer regions can limit leaf size for plants experiencing drought, and whether the heterogeneity of function across the leaf surface represents a particular disadvantage for large simple leaves that might explain their global rarity, even in resource-rich environments. PMID:23776594

The heterogeneity and spatial patterning of structure and physiology across the leaf surface in giant leaves of Alocasia macrorrhiza.

PubMed

Li, Shuai; Zhang, Yong-Jiang; Sack, Lawren; Scoffoni, Christine; Ishida, Atsushi; Chen, Ya-Jun; Cao, Kun-Fang

2013-01-01

Leaf physiology determines the carbon acquisition of the whole plant, but there can be considerable variation in physiology and carbon acquisition within individual leaves. Alocasia macrorrhiza (L.) Schott is an herbaceous species that can develop very large leaves of up to 1 m in length. However, little is known about the hydraulic and photosynthetic design of such giant leaves. Based on previous studies of smaller leaves, and on the greater surface area for trait variation in large leaves, we hypothesized that A. macrorrhiza leaves would exhibit significant heterogeneity in structure and function. We found evidence of reduced hydraulic supply and demand in the outer leaf regions; leaf mass per area, chlorophyll concentration, and guard cell length decreased, as did stomatal conductance, net photosynthetic rate and quantum efficiency of photosystem II. This heterogeneity in physiology was opposite to that expected from a thinner boundary layer at the leaf edge, which would have led to greater rates of gas exchange. Leaf temperature was 8.8°C higher in the outer than in the central region in the afternoon, consistent with reduced stomatal conductance and transpiration caused by a hydraulic limitation to the outer lamina. The reduced stomatal conductance in the outer regions would explain the observed homogeneous distribution of leaf water potential across the leaf surface. These findings indicate substantial heterogeneity in gas exchange across the leaf surface in large leaves, greater than that reported for smaller-leafed species, though the observed structural differences across the lamina were within the range reported for smaller-leafed species. Future work will determine whether the challenge of transporting water to the outer regions can limit leaf size for plants experiencing drought, and whether the heterogeneity of function across the leaf surface represents a particular disadvantage for large simple leaves that might explain their global rarity, even in resource-rich environments.

Dependence of the residual surface resistance of superconducting radio frequency cavities on the cooling dynamics around T c

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romanenko, A.; Grassellino, A.; Melnychuk, O.

We report a strong effect of the cooling dynamics throughmore » $$T_\\mathrm{c}$$ on the amount of trapped external magnetic flux in superconducting niobium cavities. The effect is similar for fine grain and single crystal niobium and all surface treatments including electropolishing with and without 120$$^\\circ$$C baking and nitrogen doping. Direct magnetic field measurements on the cavity walls show that the effect stems from changes in the flux trapping efficiency: slow cooling leads to almost complete flux trapping and higher residual resistance while fast cooling leads to the much more efficient flux expulsion and lower residual resistance.« less

Serum antibodies to outer membrane proteins (OMPs) of Moraxella (Branhamella) catarrhalis in patients with bronchiectasis: identification of OMP B1 as an important antigen.

PubMed Central

Sethi, S; Hill, S L; Murphy, T F

1995-01-01

Moraxella (Branhamella) catarrhalis is a common cause of lower respiratory tract infections in adults and of otitis media in children. Little is known about the human immune response to this bacterium. In this study, immunoblot assays were performed to detect serum immunoglobulin G antibodies directed at purified outer membrane of M. catarrhalis. Twelve serum samples, two each from six patients with bronchiectasis who were persistently colonized with this organism, were tested with their homologous M. catarrhalis sputum isolates. In all the sera, the most prominent and consistent antibody response was to a minor 84-kDa outer membrane protein, OMP B1. Immunoblot adsorption assays show that these antibodies recognize surface exposed epitopes on OMP B1. Further analysis of human serum antibodies eluted from the surface of intact bacterial cells shows that these surface-exposed epitopes on OMP B1 are heterogeneous among strains of M. catarrhalis. OMP B1 is therefore an important OMP antigen on the surface of M. catarrhalis for the human immune response to infection by this bacterium. PMID:7890418

Superficial Macromolecular Arrays on the Cell Wall of Spirillum putridiconchylium

PubMed Central

Beveridge, T. J.; Murray, R. G. E.

1974-01-01

Electron microscopy of the cell envelope of Spirillum putridiconchylium, using negatively stained, thin-sectioned, and replicated freeze-etched preparations, showed two superficial wall layers forming a complex macromolecular pattern on the external surface. The outer structured layer was a linear array of particles overlying an inner tetragonal array of larger subunits. They were associated in a very regular fashion, and the complex was bonded to the outer, pitted surface of the lipopolysaccharide tripartite layer of the cell wall. The relationship of the components of the two structured layers was resolved with the aid of optical diffraction, combined with image filtering and reconstruction and linear and rotary integration techniques. The outer structural layer consisted of spherical 1.5-nm units set in double lines determined by the size and arrangement of 6- by 3-nm inner structural layer subunits, which bore one outer structural layer unit on each outer corner. The total effect of this arrangement was a double-ridged linear structure that was evident in surface replicas and negatively stained fragments of the whole wall. The packing of these units was not square but skewed by 2° off the perpendicular so that the “unit array” described by optical diffraction and linear integration appeared to be a deformed tetragon. The verity of the model was checked by using a photographically reduced image to produce an optical diffraction pattern for comparison with that of the actual layers. The correspondence was nearly perfect. Images PMID:4137219

Spreading dynamics of superposed liquid drops on a spinning disk

NASA Astrophysics Data System (ADS)

Sahoo, Subhadarshinee; Orpe, Ashish V.; Doshi, Pankaj

2018-01-01

We have experimentally studied simultaneous spreading of superposed drops of two Newtonian liquids on top of a horizontal spinning disk using the flow visualization technique. An inner drop of high surface tension liquid is placed centrally on the disk followed by a drop of outer liquid (lower surface tension) placed exactly above that. The disk is then rotated at a desired speed for a range of volume ratios of two liquids. Such an arrangement of two superposed liquid drops does not affect the spreading behavior of the outer liquid but influences that of the inner liquid significantly. The drop spreads to a larger extent and breaks into more fingers (Nf) as compared to the case where the same liquid is spreading in the absence of outer liquid. The experimentally observed number of fingers is compared with the prediction using available theory for single liquid. It is found that the theory over-predicts the value of Nf for the inner liquid while it is covered by an outer liquid. We provide a theoretical justification for this observation using linear stability analysis. Our analysis demonstrates that for small but finite surface tension ratio of the two liquids, the presence of the outer interface reduces the value of the most unstable wave number which is equivalent to the decrease in the number of fingers observed experimentally. Finally, sustained rotation of the disk leads to the formation of droplets at the tip of the fingers traveling outwards.

EAARL coastal topography-Northern Outer Banks, North Carolina, post-Nor'Ida, 2009

USGS Publications Warehouse

Bonisteel-Cormier, J.M.; Nayegandhi, Amar; Wright, C.W.; Sallenger, A.H.; Brock, J.C.; Nagle, D.B.; Vivekanandan, Saisudha; Klipp, E.S.; Fredericks, Xan

2011-01-01

This DVD contains lidar-derived first-surface (FS) and bare-earth (BE) topography GIS datasets of a portion of the northern Outer Banks beachface in North Carolina. These datasets were acquired post-Nor'Ida on November 27 and 29, 2009.

Ferrules seals

DOEpatents

Smith, J.L.

1984-07-10

A device is provided for sealing an inner tube and an outer tube without excessively deforming the tubes. The device includes two ferrules which cooperate to form a vacuum-tight seal between the inner tube and outer tube and having mating surfaces such that overtightening is not possible. 3 figs.

Characterization of trapped charges distribution in terms of mirror plot curve.

PubMed

Al-Obaidi, Hassan N; Mahdi, Ali S; Khaleel, Imad H

2018-01-01

Accumulation of charges (electrons) at the specimen surface in scanning electron microscope (SEM) lead to generate an electrostatic potential. By using the method of image charges, this potential is defined in the chamber's space of such apparatus. The deduced formula is expressed in terms a general volumetric distribution which proposed to be an infinitesimal spherical extension. With aid of a binomial theorem the defined potential is expanded to a multipolar form. Then resultant formula is adopted to modify a novel mirror plot equation so as to detect the real distribution of trapped charges. Simulation results reveal that trapped charges may take a various sort of arrangement such as monopole, quadruple and octuple. But existence of any of these arrangements alone may never be take place, rather are some a formations of a mix of them. Influence of each type of these profiles depends on the distance between the incident electron and surface of a sample. Result also shows that trapped charge's amount of trapped charges can refer to a threshold for failing of point charge approximation. Copyright © 2017 Elsevier B.V. All rights reserved.

Identification of the spatial location of deep trap states in AlGaN/GaN heterostructures by surface photovoltage spectroscopy

NASA Astrophysics Data System (ADS)

Jana, Dipankar; Porwal, S.; Sharma, T. K.

2017-12-01

Spatial and spectral origin of deep level defects in molecular beam epitaxy grown AlGaN/GaN heterostructures are investigated by using surface photovoltage spectroscopy (SPS) and pump-probe SPS techniques. A deep trap center ∼1 eV above the valence band is observed in SPS measurements which is correlated with the yellow luminescence feature in GaN. Capture of electrons and holes is resolved by performing temperature dependent SPS and pump-probe SPS measurements. It is found that the deep trap states are distributed throughout the sample while their dominance in SPS spectra depends on the density, occupation probability of deep trap states and the background electron density of GaN channel layer. Dynamics of deep trap states associated with GaN channel layer is investigated by performing frequency dependent photoluminescence (PL) and SPS measurements. A time constant of few millisecond is estimated for the deep defects which might limit the dynamic performance of AlGaN/GaN based devices.

Comparison of secondary flows and boundary-layer accumulations in several turbine nozzles

NASA Technical Reports Server (NTRS)

Kofskey, Milton G; Allen, Hubert W; Herzig, Howard Z

1953-01-01

An investigation was made of losses and secondary flows in three different turbine nozzle configurations in annular cascade. Appreciable outer shroud loss cores (passage vortices) were found to exist at the discharge of blades which had thickened suction surface boundary layers near the outer shroud. Blade designs having thinner boundary layers did not show such outer shroud loss cores, but indicated greater inward radial flow of low momentum air, in the wake loss is to this extent an indication of the presence or absence of radial flow. The blade wake was a combination of profile loss and low momentum air from the outer shroud, and the magnitude of the wake loss is to this extent an indication of the presence or absence of radial flow. At a high Mach number, shock-boundary-layer thickening on the blade suction surfaces provided an additional radial flow path for low momentum air, which resulted in large inner shroud loss regions accompanied by large deviations from design values of discharge angle. (author)

Magnetocentrifugally Driven Flows from Young Stars and Disks. IV. The Accretion Funnel and Dead Zone

NASA Astrophysics Data System (ADS)

Ostriker, Eve C.; Shu, Frank H.

1995-07-01

We formulate the time-steady, axisymmetric problem of stellar magnetospheric inflow of gas from a surrounding accretion disk. The computational domain is bounded on the outside by a surface of given shape containing the open field lines associated with an induced disk wind. The mechanism for this wind has been investigated in previous publications in this journal. Our zeroth-order solution incorporates an acceptable accounting of the pressure balance between the magnetic field lines loaded with accreting gas (funnel flow) and those empty of matter (dead zone). In comparison with previous models, our funnel-flow/dead-zone solution has the following novel features: (1) Because of a natural tendency for the trapped stellar magnetic flux to pinch toward the corotation radius Rx (X-point of the effective potential), most of the interesting magnetohydrodynamics is initiated within a small neighborhood of Rx (X-region), where the Keplerian angular speed of rotation in the disk equals the spin rate of the star. (2) Unimpeded funnel flow from the inner portion of the X-region to the star can occur when the amount of trapped magnetic flux equals or exceeds 1.5 times the unperturbed dipole flux that would lie outside Rx in the absence of an accretion disk. (3). Near the equatorial plane, radial infall from the X-point is terminated at a "kink" point Rk = 0.74Rx that deflects the flow away from the midplane, mediating thereby between the field topology imposed by a magnetic fan of trapped flux at Rx and the geometry of a strong stellar dipole. (4) The excess angular momentum of accretion that would otherwise spin up the star rapidly is deposited by the magnetic torques of the funnel flow into the inner portion of the X-region of the disk. (5) An induced disk wind arises in the outer portion of the .X-region, where the stellar field lines have been blown open, and removes whatever excess angular momentum that viscous torques do not transport to the outer disk. (6) The interface between open field lines loaded with outflowing matter (connected to the disk) and those not loaded (connected to the star) forms a "helmet streamer," along which major mass-ejection and reconnection events may arise in response to changing boundary conditions (e.g., stellar magnetic cycles), much the way that such events occur in the active Sun. (7) Pressure balance across the dead-zone/wind interface will probably yield an asymptotically vertical (i.e., "jetlike") trajectory for the matter ejected along the helmet streamer, but mathematical demonstration of this fact is left for future studies. (8) In steady state the overall balance of angular momentum in the star/disk/ magnetosphere system fixes the fractions, f and 1 - f, of the disk mass accretion rate into the X-region carried away, respectively, by the wind and funnel flows.

Evidence of protocarnivory in triggerplants (Stylidium spp.; Stylidiaceae).

PubMed

Darnowski, D W; Carroll, D M; Płachno, B; Kabanoff, E; Cinnamon, E

2006-11-01

Australian triggerplants (Stylidium spp.; Stylidiaceae) trap small insects using mucilage-secreting glandular hairs held at various points on their inflorescence stems and flower parts. Triggerplants are generally found in habitats also containing genera of plants already accepted as carnivorous, two of which (Drosera, Byblis) use the same basic mechanism as Stylidium to trap their prey. In the herbarium, sheets of triggerplants and of accepted groups of carnivorous plants held similar numbers of trapped insects, and in the field, trapping of small prey per unit of glandular surface area was the same at a given site for triggerplants and for nearby carnivorous plants at three sites in northern Australia. Even more important, protease activity was produced by glandular regions of both triggerplants and Drosera after induction with yeast extract. A panel of negative and positive controls, including use 1) of plants grown in tissue culture, which therefore lack surface microorganisms, and 2) of protease inhibitors, shows that this activity 1) is generated by the glandular regions of the triggerplant itself, not by organisms that might reside on the surface of the plants, and 2) is due to proteases. All of this evidence taken together provides strong evidence of protocarnivory in Stylidium, something not previously suggested in the scientific literature, though the insect trapping has been noted informally. Experiments remain to be done to determine nutrient uptake, so triggerplants may well be fully carnivorous.

Evaluating the Sonic Layer Depth Relative to the Mixed Layer Depth

DTIC Science & Technology

2008-07-24

upper ocean to trap acoustic energy in a surface duct while MLD characterizes upper ocean mixing. The SLD is computed from temperature and salinity...and compared over the annual cycle. The SLD characterizes the potential of the upper ocean to trap acoustic energy in a surface duct while MLD...exists a tropical cyclone formation [e.g., Mao et al., 2000], to Minimum acoustic Cutoff Frequency (MCF) above which phytoplankton bloom critical depth

Trapping of drops by wetting defects

PubMed Central

't Mannetje, Dieter; Ghosh, Somnath; Lagraauw, Rudy; Otten, Simon; Pit, Arjen; Berendsen, Christian; Zeegers, Jos; van den Ende, Dirk; Mugele, Frieder

2014-01-01

Controlling the motion of drops on solid surfaces is crucial in many natural phenomena and technological processes including the collection and removal of rain drops, cleaning technology and heat exchangers. Topographic and chemical heterogeneities on solid surfaces give rise to pinning forces that can capture and steer drops in desired directions. Here we determine general physical conditions required for capturing sliding drops on an inclined plane that is equipped with electrically tunable wetting defects. By mapping the drop dynamics on the one-dimensional motion of a point mass, we demonstrate that the trapping process is controlled by two dimensionless parameters, the trapping strength measured in units of the driving force and the ratio between a viscous and an inertial time scale. Complementary experiments involving superhydrophobic surfaces with wetting defects demonstrate the general applicability of the concept. Moreover, we show that electrically tunable defects can be used to guide sliding drops along actively switchable tracks—with potential applications in microfluidics. PMID:24721935

Engineering the temporal response of photoconductive photodetectors via selective introduction of surface trap states.

PubMed

Konstantatos, Gerasimos; Levina, Larissa; Fischer, Armin; Sargent, Edward H

2008-05-01

Photoconductive photodetectors fabricated using simple solution-processing have recently been shown to exhibit high gains (>1000) and outstanding sensitivities ( D* > 10(13) Jones). One ostensible disadvantage of exploiting photoconductive gain is that the temporal response is limited by the release of carriers from trap states. Here we show that it is possible to introduce specific chemical species onto the surfaces of colloidal quantum dots to produce only a single, desired trap state having a carefully selected lifetime. In this way we demonstrate a device that exhibits an attractive photoconductive gain (>10) combined with a response time ( approximately 25 ms) useful in imaging. We achieve this by preserving a single surface species, lead sulfite, while eliminating lead sulfate and lead carboxylate. In doing so we preserve the outstanding sensitivity of these devices, achieving a specific detectivity of 10(12) Jones in the visible, while generating a temporal response suited to imaging applications.

Method of treating inflammatory diseases using a radiolabeled ferric hydroxide calloid

DOEpatents

Atcher, Robert W.; Hines, John J.

1992-01-01

A ferric hydroxide colloid having an alpha-emitting radionuclide essentially on the outer surfaces and a method of forming same. The method includes oxidizing a ferrous hydroxide to ferric hydroxide in the presence of a preselected radionuclide to form a colloid having the radionuclide on the outer surface thereof, and thereafter washing the colloid, and suspending the washed colloid in a suitable solution. The labelled colloid is useful in cancer therapy and for the treatment of inflamed joints.

Turbine blade vibration dampening

DOEpatents

Cornelius, C.C.; Pytanowski, G.P.; Vendituoli, J.S.

1997-07-08

The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass ``M`` or combined mass ``CM`` of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics. 5 figs.

Turbine blade vibration dampening

DOEpatents

Cornelius, Charles C.; Pytanowski, Gregory P.; Vendituoli, Jonathan S.

1997-07-08

The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass "M" or combined mass "CM" of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics.

The influence of surface roughness on volatile transport on the Moon

NASA Astrophysics Data System (ADS)

Prem, P.; Goldstein, D. B.; Varghese, P. L.; Trafton, L. M.

2018-01-01

The Moon and other virtually airless bodies provide distinctive environments for the transport and sequestration of water and other volatiles delivered to their surfaces by various sources. In this work, we conduct Monte Carlo simulations of water vapor transport on the Moon to investigate the role of small-scale roughness (unresolved by orbital measurements) in the migration and cold-trapping of volatiles. Observations indicate that surface roughness, combined with the insulating nature of lunar regolith and the absence of significant exospheric heat flow, can cause large variations in temperature over very small scales. Surface temperature has a strong influence on the residence time of migrating water molecules on the lunar surface, which in turn affects the rate and magnitude of volatile transport to permanently shadowed craters (cold traps) near the lunar poles, as well as exospheric structure and the susceptibility of migrating molecules to photodestruction. Here, we develop a stochastic rough surface temperature model suitable for simulations of volatile transport on a global scale, and compare the results of Monte Carlo simulations of volatile transport with and without the surface roughness model. We find that including small-scale temperature variations and shadowing leads to a slight increase in cold-trapping at the lunar poles, accompanied by a slight decrease in photodestruction. Exospheric structure is altered only slightly, primarily at the dawn terminator. We also examine the sensitivity of our results to the temperature of small-scale shadows, and the energetics of water molecule desorption from the lunar regolith - two factors that remain to be definitively constrained by other methods - and find that both these factors affect the rate at which cold trap capture and photodissociation occur, as well as exospheric density and longevity.

Charge Storage, Conductivity and Charge Profiles of Insulators as Related to Spacecraft Charging

NASA Technical Reports Server (NTRS)

Dennison, J. R.; Swaminathan, Prasanna; Frederickson, A. R.

2004-01-01

Dissipation of charges built up near the surface of insulators due to space environment interaction is central to understanding spacecraft charging. Conductivity of insulating materials is key to determine how accumulated charge will distribute across the spacecraft and how rapidly charge imbalance will dissipate. To understand these processes requires knowledge of how charge is deposited within the insulator, the mechanisms for charge trapping and charge transport within the insulator, and how the profile of trapped charge affects the transport and emission of charges from insulators. One must consider generation of mobile electrons and holes, their trapping, thermal de-trapping, mobility and recombination. Conductivity is more appropriately measured for spacecraft charging applications as the "decay" of charge deposited on the surface of an insulator, rather than by flow of current across two electrodes around the sample. We have found that conductivity determined from charge storage decay methods is 102 to 104 smaller than values obtained from classical ASTM and IEC methods for a variety of thin film insulating samples. For typical spacecraft charging conditions, classical conductivity predicts decay times on the order of minutes to hours (less than typical orbit periods); however, the higher charge storage conductivities predict decay times on the order of weeks to months leading to accumulation of charge with subsequent orbits. We found experimental evidence that penetration profiles of radiation and light are exceedingly important, and that internal electric fields due to charge profiles and high-field conduction by trapped electrons must be considered for space applications. We have also studied whether the decay constants depend on incident voltage and flux or on internal charge distributions and electric fields; light-activated discharge of surface charge to distinguish among differing charge trapping centers; and radiation-induced conductivity. Our experiments also show that "Malter" electron emission occurs for hours after turning off the electron beam. This Malter emission similar to emission due to negative electron affinity in semiconductors is a result of the prior radiation or optical excitations of valence electrons and their slow drift among traps towards the surface where they are subsequently emitted. This work is supported through funding from the NASA Space Environments and Effects Program.

Super-Earths as Failed Cores in Orbital Migration Traps

NASA Astrophysics Data System (ADS)

Hasegawa, Yasuhiro

2016-11-01

I explore whether close-in super-Earths were formed as rocky bodies that failed to grow fast enough to become the cores of gas giants before the natal protostellar disk dispersed. I model the failed cores’ inward orbital migration in the low-mass or type I regime to stopping points at distances where the tidal interaction with the protostellar disk applies zero net torque. The three kinds of migration traps considered are those due to the dead zone's outer edge, the ice line, and the transition from accretion to starlight as the disk's main heat source. As the disk disperses, the traps move toward final positions near or just outside 1 au. Planets at this location exceeding about 3 M ⊕ open a gap, decouple from their host traps, and migrate inward in the high-mass or type II regime to reach the vicinity of the star. I synthesize the population of planets that formed in this scenario, finding that a fraction of the observed super-Earths could have been failed cores. Most super-Earths that formed this way have more than 4 M ⊕, so their orbits when the disks dispersed were governed by type II migration. These planets have solid cores surrounded by gaseous envelopes. Their subsequent photoevaporative mass loss is most effective for masses originally below about 6 M ⊕. The failed core scenario suggests a division of the observed super-Earth mass-radius diagram into five zones according to the inferred formation history.

Synergism of Saturn, Enceladus and Titan and Formation of HCNO Prebiotic Molecules

NASA Technical Reports Server (NTRS)

Sittler, Edward C.; Cooper, John F.

2011-01-01

Saturn as a system has two very exotic moons Titan and Enceladus. Titan, taking in energy from Saturn's magnetosphere, solar UV irradiation, and cosmic rays, can make HCN based molecules as discussed in earlier paper by Raulin and Owen. Space radiation effects at both moons, and as coupled by the Saturn magnetosphere, could cause an unexpected series of events potentially leading to prebiotic chemical evolution at Titan with HCNO from magnetospheric oxygen as the new ingredient. The "Old Faithful" model suggests that Enceladus, highly irradiated by Saturn magnetospheric electrons and thus having a source of chemical energy from radiolytic gas production, has episodic ejections of water vapor, carbon dioxide, and various hydrocarbons into Saturn's magnetosphere. The hydrocarbons do not survive transport through the plasma environment, but oxygen ions from Enceladus water molecules become the dominant ion species in the outer magnetosphere. At Titan, Cassini discovered that 1) keV oxygen ions, evidently from Enceladus, are bombarding Titan's upper atmosphere and 2) heavy positive and negative ions exist in significant abundances within Titan's upper atmosphere. Initial models of heavy ion formation in Titan's upper atmosphere invoked polymerization of aromatics such as benzenes and their radicals to make polycyclic aromatic hydrocarbons (PAH) , while a more recent model by Sittler et al., has raised the possibility of carbon chains forming from the polymerization of acetylene and its radicals to make fullerenes. Laboratory measurements indicate that fullerenes, which are hollow carbon shells, can trap keV oxygen ions. Clustering of the fullerenes with aerosol mixtures from PAHs and the dominant nitrogen molecules could form larger aerosols enriched in trapped oxygen. Aerosol precipitation could then convey these chemically complex structures deeper into the atmosphere and to the moon surface. Ionizing solar UV, magnetospheric electron, and galactic cosmic ray irradiation would provide further energy for processing into more complex organic forms. Further ionizing irradiation from cosmic rays deep in the atmosphere "tho lin" molecules are produced with all the molecular components present from which prebiotic organic molecules can form. This synergy of Saturn system, exogenic irradiation, and molecular processes provides a potential pathway for accumulation of prebiotic chemistry on the surface of Titan. Since fullerenes are also thought to exist in interstellar space, similar processes may also occur there to seed molecular clouds with prebiotic chemical species. We will also discuss possible future laboratory experiments that could be done to investigate fullerene formation at Titan and the trapping of oxygen in fullerenes.

Premixing direct injector

DOEpatents

Johnson, Thomas Edward [Greer, SC; Stevenson, Christian Xavier [Inman, SC; York, William David [Greer, SC; Ziminsky, Willy Steve [Simpsonville, SC

2012-04-17

A fuel injection nozzle comprises a body member having an upstream wall opposing a downstream wall, a baffle member having an upstream surface and a downstream surface, a first chamber, a second chamber, a fuel inlet communicative with the first chamber operative to emit a first gas into the first chamber, and a plurality of mixing tubes, each of the mixing tubes having a tube inner surface, a tube outer surface, a first inlet communicative with an aperture in the upstream wall operative to receive a second gas, a second inlet communicative with the tube outer surface and the tube inner surface operative to translate the first gas into the mixing tube, a mixing portion operative to mix the first gas and the second gas, and an outlet communicative with an aperture in the downstream wall operative to emit the mixed first and second gasses.