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1

Apparatus and methods for installing, removing and adjusting an inner turbine shell section relative to an outer turbine shell section  

DOEpatents

A turbine includes upper and lower inner shell sections mounting the nozzles and shrouds and which inner shell is supported by pins secured to a surrounding outer shell. To disassemble the turbine for access to the inner shell sections and rotor, an alignment fixture is secured to the lower outer shell section and has pins engaging the inner shell section. To disassemble the turbine, the inner shell weight is transferred to the lower outer shell section via the alignment fixture and cradle pins. Roller assemblies are inserted through access openings vacated by support pins to permit rotation of the lower inner shell section out of and into the lower outer shell section during disassembly and assembly. The alignment fixture includes adjusting rods for adjusting the inner shell axially, vertically, laterally and about a lateral axis. A roller over-cage is provided to rotate the inner shell and a dummy shell to facilitate assembly and disassembly in the field.

Leach, David (Niskayuna, NY); Bergendahl, Peter Allen (Scotia, NY); Waldo, Stuart Forrest (Salem, NC); Smith, Robert Leroy (Milford, OH); Phelps, Robert Kim (Milford, OH)

2001-01-01

2

Stagnant lid convection in the outer shell of icy moons  

NASA Astrophysics Data System (ADS)

In the past decade, from both theoretical studies and spacecraft missions measurements, the internal structure of large icy moons including a subsurface ocean has gained an increasing support. The exact thickness of subsurface ocean, if present, depends on the detailed thermal evolution of each moon, and on its primordial composition. A crucial process is the heat transfer through the outer ice I layer, which controls the cooling of the satelitte interior. Convection is the most likely and efficient way to transfer heat through this layer, but the regime of convection (and therefore the heat transfer) depends on the rheology of the fluid. The viscosity of ice is strongly temperature dependent and thermal convection in the outer ice shell follows a stagnant lid regime : it means that a conductive stagnant lid forms at the top of the system, and convection is confined in a sublayer. Previous numerical studies including strongly temperature-dependent viscosities have already been performed in 2D Cartesian geometry allowing the determination of scaling laws relating the mean temperature and heat flux to the vigor of convection (described by the Rayleigh number) and the ratio of the top to the bottom viscosity, but 3D spherical geometry may provide a more accurate description of convection within the outer ice layer of icy moons. In this work, we model the heat transfer in spherical shells for a strongly temperature-dependent viscosity fluid heated from below. We use StagYY to run simulations for different ratios of the inner to outer radii of the ice layer (f), Rayleigh number (Ra), and thermal viscosity contrast (??). The inversion of the results of more than 30 numerical experiments allows the determination of scaling laws for the temperature of the well-mixed interior and surface heat flux. In particular, we find that depending on the curvature, the stagnant lid regime does not appear for the same values of the Rayleigh number and the viscosity contrast. These parameterizations, combined to mineral physics data (including melting curves of water + volatile systems), may be used to model the evolution of the radial structure and thus the cooling of icy moons.

Yao, Chloe; Deschamps, Frédéric; Tackley, Paul; Lowman, Julian; Sanchez-Valle, Carmen

2013-04-01

3

On convection in ice I shells of outer Solar System bodies, with detailed application to Callisto  

Microsoft Academic Search

It has been argued that the dominant non-Newtonian creep mechanisms of water ice make the ice shell above Callisto's ocean, and by inference all radiogenically heated ice I shells in the outer Solar System, stable against solid-state convective overturn. Conductive heat transport and internal melting (oceans) are therefore predicted to be, or have been, widespread among midsize and larger icy

William B. McKinnon

2006-01-01

4

Competitive ionic hydration involving outer-shell solvent: Temperature dependence  

SciTech Connect

Retardation of proton dissociation from the excited state of 1-naphthol (pK{sub a}{sup *} = 0.4) by added LiCl, MgCl{sub 2}, and CaCl{sub 2} in aqueous solutions is studied as a function of salt concentration and temperature. The observed salt effects cannot be satisfactorily explained by using the bulk properties of electrolyte solutions such as water activity. It is found that near room temperature the proton dissociation is strongly affected by an intermediate hydration region of an ion, which couples the primary solvation shell to the bulk region of the solvent. Two concepts are proposed to help classify these imperfectly defined regions: a relative hydration energy {Delta}E, which is based on the activation energy of k{sub dis}, and a temperature-dependent kinetic solvation number n{sub 0}, which defines the number of water molecules so strongly bound to the ion that they cannot participate in the proton dissociation process. The analysis of {Delta}E as a function of salt concentration and of n{sub 0} as a function of both salt concentration and temperature reveals the nature of the important solvation structure of an electrolyte at the molecular level. When comparisons with gas-phase results are made, both types of data indicate a gradual change of hydration energy with increasing hydration number, rather than discrete sets of solvent shell energies.

Lee, J. (Texas Tech Univ., Lubbock (USA))

1990-01-11

5

High-order Vibration Characteristics of Rotating Thin Shells and Hard-coating Damping Effects  

NASA Astrophysics Data System (ADS)

The high-order modes and the moving wave characteristics of rotating thin shell are investigated in this paper based on transfer matrix method when the damping effects of the hard-coating layers are applied on the shell. Firstly, the dynamic model of the thin shell is obtained based on the Love theory, with introducing centrifugal force and Coriolis force. Then, the transfer matrix formulas of the shell with partially coated layers at different segments are obtained under the clamped-free boundary condition, in which the mechanical property of the hard-coating material is simplified to be linear and isotropic. The modal characteristics of the shell are calculated numerically. The obtained higher order modal frequencies of the partially coated shells are compared with those of the bare shell. The effects of the material parameters and locations of the hard-coating layers are also illustrated based on the different modal characteristics., great care should be taken in constructing both.

Song, X. Y.; Ren, H. J.; Wang, X. P.; Li, X. J.; Han, Q. K.

2013-07-01

6

Surface Response of Spherical Core-Shell Structured Nanoparticle by Optically Induced Elastic Oscillations of Soft Shell against Hard Core  

Microsoft Academic Search

The optically induced oscillatory response of a spherical two-component, shell-core structured, nanoparticle by nodeless elastic vibrations of soft peripheral shell against hard and dynamically immobile inner core is considered. The eigenfrequencies of the even-parity, spheroidal, and odd-parity torsional vibrational modes trapped in the finite-depth shell are obtained, which are of practical interest for modal specification of individual resonances in spectra

S. I. Bastrukov; P.-Y. Lai; I. V. Molodtsova; H.-K. Chang; D. V. Podgainy

2009-01-01

7

Development of a hydrogen absorbing layer in the outer shell of high pressure hydrogen tanks  

Microsoft Academic Search

This study is focused on the development of a hydrogen absorbing Zr2Fe layer in the outer shell of high pressure (70MPa) hydrogen storage tanks. This layer aims to absorb hydrogen coming from micro-cracks, as those formed by hydrogen embrittlement of the aluminium liner. A multi-phased Zr2Fe alloy prepared by induction melting presents a very fast absorption kinetic and a maximum

R. Janot; M. Latroche; A. Percheron-Guégan

2005-01-01

8

Hard X-ray and Gamma-Ray Emission from Shell Supernova Remnants  

Microsoft Academic Search

Strong shock waves in shell supernova remnants have been shown to be capable of accelerating particles to energies in excess of 100 TeV. Electrons of these energies produce hard X-ray synchrotron emission and TeV inverse-Compton emission by upscattering cosmic microwave background photons. However, bremsstrahlung from suprathermal, nonrelativistic electrons can also produce hard X-ray emission. I calculate model X-ray and gamma-ray

S. P. Reynolds

1998-01-01

9

Effect of Sodium Lauryl Sulfate in Dissolution Media on Dissolution of Hard Gelatin Capsule Shells  

Microsoft Academic Search

Purpose. Sodium lauryl sulfate (SLS) is a commonly used surfactant in dissolution media for poorly water soluble drugs. However, it has occasionally been observed that SLS negatively impacts the dissolution of drug products formulated in gelatin capsules. This study investigated the effect of SLS on the dissolution of hard gelatin capsule shells.

Fang Zhao; Vyacheslav Malayev; Venkatramana Rao; Munir Hussain

2004-01-01

10

Mitochondrial Restriction Enzyme Screening and Phylogenetic Relatedness in the Hard Shell Clam Genus 'Mercenaria'. Part 2. Population Variation.  

National Technical Information Service (NTIS)

The report focuses on the population genetics and systematics of the hard shell clam Mercenaria, an important aquaculture species, as determined by restriction enzyme digestion of mitochondrial DNA (mtDNA). Fifteen clam populations were sampled along the ...

B. L. Brown L. Wolfinbarger

1989-01-01

11

Photoionization of the outer shells of neon, argon, krypton, and xenon using the relativistic random-phase approximation  

Microsoft Academic Search

Multichannel photoionization calculations using the relativistic random-phase approximation for the outer shells in the rare gases, neon, argon, krypton, and xenon, are presented. Total cross sections and partial cross sections for ns subshells are determined and compared with experiment and with alternative calculations at low energies. Branching ratios of ²Pââ:²Pââ cross sections which are sensitive to relativistic and correlation effects

W. R. Johnson; K. T. Cheng

1979-01-01

12

Photoionization of the outer shells of neon, argon, krypton, and xenon using the relativistic random-phase approximation  

Microsoft Academic Search

Multichannel photoionization calculations using the relativistic random-phase approximation for the outer shells in the rare gases, neon, argon, krypton, and xenon, are presented. Total cross sections and partial cross sections for ns subshells are determined and compared with experiment and with alternative calculations at low energies. Branching ratios of 2P32:2P12 cross sections which are sensitive to relativistic and correlation effects

W. R. Johnson; K. T. Cheng

1979-01-01

13

The oxidant thimerosal modulates gating behavior of KCNQ1 by interaction with the channel outer shell.  

PubMed

Thimerosal (o-Ethylmercurithio)benzoic acid, TMS), a membrane-impermeable, sulfhydryl-oxidizing agent, has been described to increase the K+ current IKs in KCNE1-injected Xenopus laevis oocytes. Since there are no cysteine residues in the extracellular domain of KCNE1, it has been proposed that TMS interacts with its partner protein KCNQ1. The aim of this study was therefore to investigate the interaction of TMS with KCNQ1 and the respective K+current IK. In CHO cells stably transfected with KCNQ1/KCNE1, TMS increased IKs, whereas in CHO cells expressing KCNQ1 alone, TMS initially decreased IK. TMS also affected the cytosolic pH (pHi) and the cytosolic Ca2+ activity ([Ca2+]i) in these cells. TMS slowly decreased pHi. With a short delay, TMS increased [Ca2+]i by store depletion and capacitative influx. The time course of the effects of TMS on pHi and [Ca2+]i did not correlate with the effect of TMS on IK. We therefore anticipated a different mode of action by TMS and investigated the influence of TMS on cysteine residues of KCNQ1. For this purpose, KCNQ1wt and two mutants lacking a cysteine residue in the S6 or the S3 segment (KCNQ1C331A and KCNQ1C214A, respectively) were expressed in Xenopus laevis oocytes. A sustained current decrease was observed in KCNQ1wt and KCNQ1C331A, but not in KCNQ1C214A-injected oocytes. The analysis of tail currents, I/V curves and activation kinetics revealed a complex effect of TMS on the gating of KCNQ1wt and KCNQ1C331A. In another series we investigated the effect of TMS on IKs. TMS increased IKs of KCNQ1C214A/KCNE1-injected oocytes significantly less than IKs in KCNQ1wt/KCNE1- or KCNQ1C331A/KCNE1-injected cells. These results suggest that thimerosal interacts with the cysteine residue C214 in the S3 segment of KCNQ1, leading to a change of its gating properties. Our results support the idea that not only the inner shell, but also the outer shell of the channel is important for the gating behavior of voltage dependent K+ channels. PMID:11944086

Kerst, G; Brousos, H; Schreiber, R; Nitschke, R; Hug, M J; Greger, R; Bleich, M

2002-03-15

14

VideoLab: Holding on by a (Hard-Shell) Thread  

NSDL National Science Digital Library

Similar in concept to spider silk, mussels use a thread-like, acellular tissue called the byssus (or âÂÂbeardâÂÂ) to anchor themselves in turbulent aqueous environments. The movie shows the musselâÂÂs foot attaching to and detaching from a surface, leaving behind an adhesive pad and rope-like byssal thread that keeps the mussel affixed to the surface. A Perspective by P.B. Messersmith reports on recent study of the chemistry of byssal thread cuticles. It highlights the importance of the catecholic amino acid dopa, which coordinates with iron to fabricate the byssus' hard-shelled cuticles.

Phillip B. Messersmith (Northwestern University;Departments of Biomedical Engineering, Materials Science and Engineering, Chemical and Biological Engineering, Chemistry of Life Processes Institute, and Institute for Bionanotechnology in Medicine)

2010-04-09

15

Protistan parasite QPX of hard-shell clam Mercenaria mercenaria is a member of Labyrinthulomycota.  

PubMed

Biomass of the protistan parasite QPX (quahaug parasite X) of hard-shell clam Mercenaria mercenaria was enriched from in vitro culture. The nuclear gene encoding the 18S RNA of the small-subunit ribosomal (ssu-rDNA) was recovered using the polymerase chain reaction (PCR) and sequenced. Phylogenetic analysis clearly showed that QPX is a member of phylum Labyrinthulomycota, within which it appears as a specific relative of Thraustochytrium pachydermum. These results confirm the provisional assignment of QPX to the Labyrinthulomycota made previously on the basis of morphological and ultrastructural characters found in some, but not all, geographic isolates. PMID:11104069

Ragan, M A; MacCallum, G S; Murphy, C A; Cannone, J J; Gutell, R R; McGladdery, S E

2000-09-28

16

Thin shell plastic optics: Application to hard X-ray telescopes  

NASA Astrophysics Data System (ADS)

We present new results from a program to develop large area X-ray telescopes that are made from thin plastic shells. We use multi-shell cylindrical lenses in a point-to-point configuration to form full aperture images of the small focal spot in an X-ray tube on a microchannel plate detector. The image data are analyzed to yield radial profiles and encircled energy curves. The derived parameters (FWHM and HEW) can be extrapolated to the case of a telescope that is a conical approximation to Wolter 1 optics. The plastic shells can be coated with suitable mono- or multilayers that allow for a wideband coverage of X-ray energies. Our current program is focused on the development of a large area, hard X-ray telescope for a balloon payload (B-MINE). Our goal is to detect the 68 and 78 keV 44Ti lines from the CAS-A supernova remnant. The B-MINE microcalorimeter detector has a 50 eV (FWHM) energy resolution and almost no internal bakground. This combination of a low background and a narrow FWHM detector allows us to distinguish between narrow and broad emission lines. We use the SAX CAS-A results to predict a B-MINE detection of 70 sigma at 68 keV.

Schnopper, H. W.; Barbera, M.; Silver, E. H.; Murray, S. S.

2002-12-01

17

Effects of an outer stably stratified layer on equatorial surface flows induced by thermal convection in a rotating spherical shell  

NASA Astrophysics Data System (ADS)

In order to explain the equatorial superrotation states observed in Jupiter, Saturn and the sun, possible roles of thermal convection in rotating spherical shells have been investigated. Most of the studies on thermal convection in rotating spherical shells consider situations in which the entire layer is thermally unstable. However, the actual planetary atmospheres may not consist of entirely unstable layers. There exist stable stratospheres and possibly moderately stable cloud layers. Below the cloud layer, the Galileo spacecraft observed a stable layer between depths of 5 and 16 bars in the Jovian atmosphere. If such a stable layer exists near the outer boundary, the generation of surface prograde mean zonal flows caused by the angular momentum transport due to the tilting of columnar convection cells might not operate. Therefore, in the present study, we perform systematic numerical experiments of finite amplitude thermal convection in a rotating spherical shell with an outer stably stratified layer. The Ekman number, the Prandtl number, and the inner/outer radius ratio of the shell are fixed to 10-3, 1, and 0.4, respectively. The Rayleigh number is varied from a few times to approximately forty times the critical value. The temperature gradient in the stable layer is increased from 1 to 104 times that of the inner unstable layer. The conditions at the boundaries are free-slip and fixed temperature. The time integrations are started from the state of rest accompanied by a point-like temperature disturbance, and continue until the kinetic energy becomes almost stationary. The results show that the existence of a strongly stratified upper layer enhances the generation of equatorial surface retrograde flows when he Rayleigh number is approximately ten times larger than the critical value. These retrograde flows are not associated with the homogenization of angular momentum. It could be explained by change of an effective outer boundary condition operating on the convective motion in the inner layer. The existence of the stable layer causes the bottom of the stable layer to behave as a virtual boundary for the convective motion underneath. Its effective dynamic condition varies from the free-slip condition to the no-slip condition as the Rayleigh number increases. The Reynolds stress of the convective vortices beneath the stable layer is weakened and is dominated by the transport of the planetary angular momentum. As a result, the latitudinal temperature gradient produced at the bottom of the stable layer induces the equatorial retrograde flow. This diffuses through the stable layer by viscosity and produces the equatorial surface retrograde flow.

Takehiro, S.; Yamada, M.; Hayashi, Y.

2011-12-01

18

Influence of multiple outer-shell electron stripping on the K? and K? x-ray energies of iridium  

NASA Astrophysics Data System (ADS)

We present theoretical predictions for iridium K?1,2, K?1,3 and K?2 energy shifts as a function of outer-shell stripping, evaluated using the multiconfiguration Dirac-Fock method including Breit interaction and QED corrections. The energy shifts are consistent with the K-lines emitted by the plasma made in the plasma-filled rod pinch, and potentially relevant to diagnostics of high-energy density laser-produced plasmas as studied in connection with the National Ignition Facility.

Rzadkiewicz, J.; S?abkowska, K.; Polasik, M.; Starosta, J.; Szyma?ska, E.; Kozio?, K.; Scholz, M.; Pereira, N. R.

2013-09-01

19

Environmental salinity modulates the effects of elevated CO2 levels on juvenile hard-shell clams, Mercenaria mercenaria.  

PubMed

Ocean acidification due to increasing atmospheric CO2 concentrations results in a decrease in seawater pH and shifts in the carbonate chemistry that can negatively affect marine organisms. Marine bivalves such as the hard-shell clam, Mercenaria mercenaria, serve as ecosystem engineers in estuaries and coastal zones of the western Atlantic and, as for many marine calcifiers, are sensitive to the impacts of ocean acidification. In estuaries, the effects of ocean acidification can be exacerbated by low buffering capacity of brackish waters, acidic inputs from freshwaters and land, and/or the negative effects of salinity on the physiology of organisms. We determined the interactive effects of 21 weeks of exposure to different levels of CO2 (~395, 800 and 1500 ?atm corresponding to pH of 8.2, 8.1 and 7.7, respectively) and salinity (32 versus 16) on biomineralization, shell properties and energy metabolism of juvenile hard-shell clams. Low salinity had profound effects on survival, energy metabolism and biomineralization of hard-shell clams and modulated their responses to elevated PCO2. Negative effects of low salinity in juvenile clams were mostly due to the strongly elevated basal energy demand, indicating energy deficiency, that led to reduced growth, elevated mortality and impaired shell maintenance (evidenced by the extensive damage to the periostracum). The effects of elevated PCO2 on physiology and biomineralization of hard-shell clams were more complex. Elevated PCO2 (~800-1500 ?atm) had no significant effects on standard metabolic rates (indicative of the basal energy demand), but affected growth and shell mechanical properties in juvenile clams. Moderate hypercapnia (~800 ?atm PCO2) increased shell and tissue growth and reduced mortality of juvenile clams in high salinity exposures; however, these effects were abolished under the low salinity conditions or at high PCO2 (~1500 ?atm). Mechanical properties of the shell (measured as microhardness and fracture toughness of the shells) were negatively affected by elevated CO2 alone or in combination with low salinity, which may have important implications for protection against predators or environmental stressors. Our data indicate that environmental salinity can strongly modulate responses to ocean acidification in hard-shell clams and thus should be taken into account when predicting the effects of ocean acidification on estuarine bivalves. PMID:23531824

Dickinson, Gary H; Matoo, Omera B; Tourek, Robert T; Sokolova, Inna M; Beniash, Elia

2013-03-26

20

Twin polymerization at spherical hard templates: an approach to size-adjustable carbon hollow spheres with micro- or mesoporous shells.  

PubMed

Kitset hollow spheres: The combination of twin polymerization with hard templates makes hollow carbon spheres (HCSs) with tailored properties easily accessible. The thickness and pore texture of the HCS shells and also the diameter of the spherical cavity can be varied. The application potential of synthesized HCS is substantiated by an excellent cycling stability of lithium-sulfur batteries. PMID:23620268

Böttger-Hiller, Falko; Kempe, Patrick; Cox, Gerhard; Panchenko, Alexander; Janssen, Nicole; Petzold, Albrecht; Thurn-Albrecht, Thomas; Borchardt, Lars; Rose, Marcus; Kaskel, Stefan; Georgi, Colin; Lang, Heinrich; Spange, Stefan

2013-04-25

21

Influence of multiple outer-shell electron stripping on the L?, L? and L? x-ray energies of tungsten  

NASA Astrophysics Data System (ADS)

Gradually stripping tungsten of its outer-shell electrons tends to increase the x-ray energies of the various L?, L? and L? x-ray lines. For the L?1 and L?1 lines the energy change is sometimes negative but always less than ?10 eV when the ionization remains below W30+; other lines increase their energy approximately quadratically with ionization level. Beyond W30+ the increase is dramatic and some lines blue-shift many hundreds of eV already at W40+. The computations are carried out with a multiconfiguration Dirac-Fock method that includes the Breit interaction and some QED corrections. The results are relevant to high-resolution x-ray diagnostics of plasma produced by short-pulse lasers and to some pulsed power plasmas.

S?abkowska, Katarzyna

2013-09-01

22

Fabrication of Submicrometer Pores with an Outer Shell Using Modified Poly(vinyl alcohol) and the Molecular or Particle Collection Effect.  

PubMed

Pores with an outer shell (POS) are fabricated on the submicrometer scale using modified poly(vinyl alcohol) (PVA). An aqueous solution is mixed with cationic PVA and a water-based colloidal suspension of polystyrene (PS) spheres of submicrometer diameter. The mixture is then spin-coated onto a substrate. The resultant structure is immersed in toluene, which dissolves the PS spheres. As a result, POS are formed by PVA on the substrate. By using PS spheres with 500 nm diameter, the pore openings have a diameter of about 300 nm and are surrounded by the outer shell. This structure exhibits beneficial molecular and particle collection effects, which are attributed to the peripheral shell rising from the surface. In addition, POS can be formed using a photo-cross-linkable PVA that is often used for enzyme-immobilized hydrogel matrices. PMID:24067099

Emoto, Akira; Noguchi, Naomi; Kobayashi, Tomoko; Fukuda, Takashi

2013-09-26

23

The development of a sensitive methodology to characterise hard shell capsule puncture by dry powder inhaler pins.  

PubMed

In order for hard-shell capsules to function effectively as drug reservoirs in dry powder inhalers, the capsule must be punctured with sharpened pins to release the powdered medicament upon inspiration. Capsule performance in this setting is poorly understood. This study aims to develop a methodology to characterise hard shell capsule penetration by needles from commercial dry powder inhalers, to determine whether changes to capsule materials impact on their performance. Two pin types from two commercial dry powder inhalers were mounted in a material-testing machine, equipped with a 500N load cell. A stainless steel bush was used to secure a capsule directly below the steel pin. Hypromellose (n=10) and gelatin capsules (n=10) were conditioned in 'normal' or low humidity conditions and were subsequently punctured with both types of pin. Each puncture event was recorded on a load-displacement curve. The force required for puncture was 2.82±0.26N for hypromellose capsules and 4.54±0.26N for gelatin capsules, stored in normal humidity. Different capsule materials possessed distinguishable signature profiles but repeated force-displacement profiles were highly reproducible i.e. intra-individual variability was minimal. A rapid, robust yet sensitive methodology has therefore been developed that is able to characterise hard shell capsule materials based on the puncture performance. PMID:23965433

Torrisi, Barbara M; Birchall, James C; Jones, Brian E; Díez, Fernando; Coulman, Sion A

2013-08-18

24

Evidence for Significant Target Outer-Shell Excitation in Multiple-Electron Capture Collisions of Slow Highly Charged Ions with Many-Electron Atoms  

Microsoft Academic Search

Unequivocal evidence for significant target outer-shell excitation accompanying multiple-electron capture, in slow collisions of highly charged ions with many-electron atoms, has been obtained by means of simultaneous Auger-electron and cold-target recoil-ion momentum spectroscopic measurements. For the 28 keV 15N7++Ar collision system, it is found that target excitation accompanies about 40% of all double-electron capture collisions. The evidence supports the predictions

A. A. Hasan; E. D. Emmons; G. Hinojosa; R. Ali

1999-01-01

25

Uptake and adherence with soft- and hard-shelled hip protectors in Norwegian nursing homes: a cluster randomised trial  

Microsoft Academic Search

Summary  A comparison between soft- and hard-shelled hip protectors in nursing homes shows no clinical relevant difference in acceptance\\u000a and probability of continued use. However, significantly more users of the soft hip protector used the protector 24 hours\\u000a a day.\\u000a \\u000a \\u000a \\u000a Introduction and hypothesis  Uptake and adherence with the use of hip protectors are poor due to discomfort and impracticality. The aim of

H. Bentzen; L. Forsén; C. Becker; A. Bergland

2008-01-01

26

Evidence for Significant Target Outer-Shell Excitation in Multiple-Electron Capture Collisions of Slow Highly Charged Ions with Many-Electron Atoms  

SciTech Connect

Unequivocal evidence for significant target outer-shell excitation accompanying multiple-electron capture, in slow collisions of highly charged ions with many-electron atoms, has been obtained by means of simultaneous Auger-electron and cold-target recoil-ion momentum spectroscopic measurements. For the 28 keV {sup 15}N{sup 7+}+Ar collision system, it is found that target excitation accompanies about 40% of all double-electron capture collisions. The evidence supports the predictions of the molecular classical overbarrier model by Niehaus [A. Niehaus, J. Phys. B 19, 2925 (1986)]. (c) 1999 The American Physical Society.

Hasan, A. A.; Emmons, E. D.; Hinojosa, G.; Ali, R.

1999-11-29

27

Mapping Areas of Hard Bottom and Other Important Bottom Types: Outer Continental Shelf and Upper Continental Slope.  

National Technical Information Service (NTIS)

As the petroleum industry moves into deeper and deeper waters of the northern Gulf of Mexico continental slope, it is important to locate and map areas of seafloor features like faults and areas of hard bottom that may constitute risks that may impact dri...

H. H. Roberts J. M. Coleman R. H. Peele

2005-01-01

28

Stratigraphy and paleoenvironments of the Shell 410-1 well, Georges Bank Basin, US North Atlantic outer continental shelf  

USGS Publications Warehouse

The Shell 410-1 well is the most downdip (seaward) hydrocarbon exploratory well in the Georges Bank Basin. It was drilled to a total depth of 4745 m RKB, and penetrated a section composed of Middle Jurassic to Quaternary sedimentary rocks. The lithostratigraphy of the section is described. The strata penetrated by the Shell 410-1 well are more marine than rocks at the updip (landward) COST G-1, Exxon 975-1, COST G-2, and Conoco 145-1 well sites. Limestones and calcareous mudstones dominate at the Shell 410-1 site. Dolomite and anhydrite are much more abundant in the Bajocian-Callovian strata of the Shell 410-1 well, which is evidence that the carbonate-bank palaeoenvironments recorded in the Iroquois and Abenaki Formations were more restricted (less marine) here than 47 km to the west-northwest at the Mobil 312-1 well site near the edge of the Jurassic carbonate platform. -from Authors

Poppe, L. J.; Poag, C. W.; Swift, B. A.

1995-01-01

29

Removal of Escherichia coli, Enterococcus fecalis, coliphage MS2, poliovirus, and hepatitis A virus from oysters (Crassostrea virginica) and hard shell clams (Mercinaria mercinaria) by depuration.  

PubMed

Filter-feeding bivalve mollusks (shellfish) can bioaccumulate pathogenic microorganisms in up to 1000-fold higher levels than overlying waters, and therefore disease risks are associated with consuming raw or partially cooked shellfish. Many of these shellfish-borne diseases are due to enteric bacteria and viruses associated with fecal contamination. To control shellfish-borne diseases, guidelines for shellfish harvest waters and shellfish meat have been devised, which include cleansing of contaminated shellfish by depuration in controlled systems, heat pasteurization, or relay to clean waters. This study examines the depuration of oysters (Crassostrea virginica) and hard shell clams (Mercinaria mercinaria) in a flow-through depuration system under variable temperature (12 °C, 18 °C, and 25 °C), salinity (8 ppt, 18 ppt, and 28 ppt), turbidity (<1NTU, 10NTU, and 20NTU), pH (pH 7 and pH 8), and algae conditions (0 cells/mL and 50,000 cells/mL), with constant dissolved oxygen (5-7 mg/L). Oysters and hard shell clams were artificially contaminated with enteric microorganisms: Escherichia coli, Enterococcus faecalis, coliphage MS2, Poliovirus type-1 and Hepatitis A virus HM-175 (HAV), then depurated in 5-day trials with daily sampling. In oysters, optimizing environmental parameters of water temperature improved E. coli, MS2, poliovirus and HAV depuration, and optimized salinity improved E. coli, E. faecalis, and MS2 depuration rates. In hard shell clams, salinity improved E. coli and E. faecalis depuration rates. Adjusting turbidity, pH or algae did not improve microorganism depuration in either oysters or hard shell clams, with the exception of turbidity on E. faecalis in hard shell clams. Microorganism depuration rates in oysters from greatest to least were: MS2>E. coli>E. faecalis>poliovirus>HAV, and in clams depuration rates from greatest to least were: E. coli>E. faecalis>HAV>MS2>poliovirus. Because E. coli and E. faecalis were removed at faster rates than HAV and poliovirus, these fecal bacteria appear to be poor process indicators of the virological quality of depurated oysters and hard shell clams. PMID:20864199

Love, David C; Lovelace, Greg L; Sobsey, Mark D

2010-09-23

30

One-pot synthesis of biocompatible Te@phenol formaldehyde resin core-shell nanowires with uniform size and unique fluorescent properties by a synergized soft-hard template process  

NASA Astrophysics Data System (ADS)

One-pot hydrothermal process has been developed to synthesize uniform Te@phenol formaldehyde resin core-shell nanowires with unique fluorescent properties. A synergistic soft-hard template mechanism has been proposed to explain the formation of the core-shell nanowires. The Te@phenol formaldehyde resin core-shell nanowires display unique fluorescent properties, which give strong luminescent emission in the blue-violet and green regions with excitation wavelengths of 270 nm and 402 nm, respectively.

Qian, Haisheng; Zhu, Enbo; Zheng, Shunji; Li, Zhengquan; Hu, Yong; Guo, Changfa; Yang, Xingyun; Li, Liangchao; Tong, Guoxiu; Guo, Huichen

2010-12-01

31

One-pot synthesis of biocompatible Te@phenol formaldehyde resin core-shell nanowires with uniform size and unique fluorescent properties by a synergized soft-hard template process.  

PubMed

One-pot hydrothermal process has been developed to synthesize uniform Te@phenol formaldehyde resin core-shell nanowires with unique fluorescent properties. A synergistic soft-hard template mechanism has been proposed to explain the formation of the core-shell nanowires. The Te@phenol formaldehyde resin core-shell nanowires display unique fluorescent properties, which give strong luminescent emission in the blue-violet and green regions with excitation wavelengths of 270 nm and 402 nm, respectively. PMID:21071820

Qian, Haisheng; Zhu, Enbo; Zheng, Shunji; Li, Zhengquan; Hu, Yong; Guo, Changfa; Yang, Xingyun; Li, Liangchao; Tong, Guoxiu; Guo, Huichen

2010-11-11

32

Efficient charge carriers induced by extra outer-shell electrons in iron-pnictides: a comparison between Ni- and Co-doped CaFeAsF  

NASA Astrophysics Data System (ADS)

A comprehensive study of the difference between CaFe1-xNixAsF and CaFe1-xCoxAsF systems has been carried out by measuring the efficient charge carrier concentration, the valence states and the superconducting phase diagram. It is found that at the same doping level, Ni doping introduces nearly twice the number of charge carriers as Co doping. However, x-ray absorption near-edge spectroscopy measurements reveal that the valence state of Fe in both systems is close to 2, indicating that there is no valence mismatch. We suggest that the charge carriers in CaFe1-xMxAsF (M=transition metal elements) are not induced by valence mismatch but come from the difference in the number of outer-shell electrons. We also suggest that with Ni and Co doping, the systems change from a multi-band material in the underdoped regions to a single-band state in the overdoped regions.

Zhang, Min; Zhang, Changjin; Yu, Yi; Zhang, Lei; Qu, Zhe; Ling, Langsheng; Xi, Chuanying; Tan, Shun; Zhang, Yuheng

2010-08-01

33

Discrimination of the hard keratins animal horn and chelonian shell using attenuated total reflection-infrared spectroscopy.  

PubMed

The ability to discriminate between objects manufactured from animal horn and chelonian (turtle, tortoise, or terrapin) shell is important from a cultural and archeological perspective such that it may allow conservators to determine the appropriate treatment and long-term care solution. It would also aid curators in identifying and cataloging items manufactured from these materials. Discrimination and classification is also a valuable tool for those involved in tracking the illegal trade in restricted materials of this nature. Attenuated total reflection infrared (ATR-IR) spectroscopy, using a single reflection diamond internal reflection element (IRE), coupled with discrimination analysis was used to analyze a total of thirty-nine samples (29 calibration samples, 10 validation samples). A discrimination analysis model was constructed using Mahalanobis distances to classify spectra into one of two classes. The model was then subsequently used to successfully classify all validation samples and correctly identify them as animal horn or chelonian shell based on second-derivative spectra of the amide I and II regions. This technique requires minimal to no sample preparation and may be used to nondestructively identify very small samples successfully without performing detailed secondary structural curve-fitting routines. This model should be a valuable resource to museums, conservators, and wildlife management programs for rapidly and reliably discriminating between animal horn and chelonian shell. PMID:22524968

Biscardi, Brianna; Welsh, Wendy; Kennedy, Anthony

2012-05-01

34

Micromechanical properties and structural characterization of modern inarticulated brachiopod shells  

NASA Astrophysics Data System (ADS)

We investigated micromechanical properties and ultrastructure of the shells of the modern brachiopod species Lingula anatina, Discinisca laevis, and Discradisca stella with scanning electron microscopy (SEM, EDX), transmission electron microscopy (TEM) and Vickers microhardness indentation analyses. The shells are composed of two distinct layers, an outer primary layer and an inner secondary layer. Except for the primary layer in Lingula anatina, which is composed entirely of organic matter, all other shell layers are laminated organic/inorganic composites. The organic matter is built of chitin fibers, which provide the matrix for the incorporation of calcium phosphate. Amorphous calcium phosphate in the outer, primary layer and crystalline apatite is deposited into the inner, secondary layer of the shell. Apatite crystallite sizes in the umbonal region of the shell are about 50 × 50 nm, while within the valves crystallite sizes are significantly smaller, averanging 10 × 25 nm. There is great variation in hardness values between shell layers and between the investigated brachiopod species. The microhardness of the investigated shells is significantly lower than that of inorganic hydroxyapatite. This is caused by the predominantly organic material component that in these shells is either developed as purely organic layers or as an organic fibrous matrix reinforced by crystallites. Our results show that this particular fiber composite material is very efficient for the protection and the support of the soft animal tissue. It lowers the probability of crack formation and effectively impedes crack propagation perpendicular to the shell by crack-deviation mechanisms. The high degree of mechanical stability and toughness is achieved by two design features. First, there is the fiber composite material which overcomes some detrimental and enhances some advantageous properties of the single constituents, that is the softness and flexibility of chitin and the hardness and brittleness of apatite. Second, there is a hierarchical structuring from the nanometer to a micrometer level. We could identify at least seven levels of hierarchy within the shells.

Merkel, C.; Griesshaber, E.; Kelm, K.; Neuser, R.; Jordan, G.; Logan, A.; Mader, W.; Schmahl, W. W.

2007-06-01

35

The ultrastructure of shelled and unshelled cashew nuts.  

PubMed

Cashew nuts have many attributes, including sensory, nutritional and health appeal, which contribute to their worldwide acceptance. We demonstrate details of the microstructure of shelled and unshelled cashew kernels with regard to pericarp and cotyledon organization. This study also provides evidence of the colonization of these kernels by filamentous fungi. Nuts were examined by scanning electron and confocal scanning laser microscopy. Staining with acridine orange was performed. A tight lignified palisade layer adjacent to the exocarp surface explains the hardness of the shell's pericarp. The mesocarp contains large secretory cavities that confer a spongy property to this tissue. Papillose cells, which are responsible for secreting CNSL (cashew nutshell liquid), were observed to cover the inner wall of these cavities. Lipid components are readily released from the parenchyma and appear as oil droplets. The outer surface of the shelled samples exhibited a dense Aspergillus infestation. PMID:24045033

Muniz, Celli R; Freire, Francisco C O; Soares, Arlete Aparecida; Cooke, Peter H; Guedes, Maria I F

2013-08-31

36

Outer-shell photodetachment of the metastable Be{sup -} 1s{sup 2}2s2p{sup 2} {sup 4}P{sup e} state  

SciTech Connect

We report calculated photodetachment cross sections from the metastable Be{sup -} 1s{sup 2}2s2p{sup 2} {sup 4}P{sup e} state in the photon energy range 0-10 eV. Outer-shell photodetachment takes place in this energy range, which includes the double-ionization threshold Be{sup +}({sup 2}S{sup e}) at {approx}7 eV as well as doubly excited thresholds of the residual atom up to the Be(1s{sup 2}2p4f) threshold at {approx}10 eV. Therefore, triply excited states of Be{sup -} are reached within the selected photon energy. We have implemented the complex scaled configuration interaction method along with a model potential for the 1s{sup 2} core to uncover the first series of Be{sup -} {sup 4}L{sup o} resonant states. In this work, four {sup 4}P{sup o}, seven {sup 4}D{sup o}, and two {sup 4}S{sup o} resonances are reported and we compare our cross section with other previous theoretical calculations, that reported none or, at most, two resonances.

Sanz-Vicario, Jose Luis; Lindroth, Eva [GFAM, Instituto de Fisica, Universidad de Antioquia, Calle 67 No. 53-108, AA 1226, Medellin, (Colombia); Atomic Physics, Stockholms Centrum Foer Fysik, Astronomi och Bioteknik (SCFAB), Stockholm University, S-106 91 Stockholm, (Sweden)

2003-07-01

37

Inner shell radial pin geometry and mounting arrangement  

SciTech Connect

Circumferentially spaced arrays of support pins are disposed through access openings in an outer turbine shell and have projections received in recesses in forward and aft sections of an inner turbine shell supported from the outer shell. The projections have arcuate sides in a circumferential direction affording line contacts with the side walls of the recesses and are spaced from end faces of the recesses, enabling radial and axial expansion and contraction of the inner shell relative to the outer shell. All loads are taken up in a tangential direction by the outer shell with the support pins taking no radial loadings.

Leach, David (Niskayuna, NY); Bergendahl, Peter Allen (Scotia, NY)

2002-01-01

38

Optimum rotationally symmetric shells for flywheel rotors  

SciTech Connect

A flywheel rim support formed from two shell halves. Each of the shell halves has a disc connected to the central shaft. A first shell element connects to the disc at an interface. A second shell element connects to the first shell element. The second shell element has a plurality of meridional slits. A cylindrical shell element connects to the second shell element. The cylindrical shell element connects to the inner surface of the flywheel rim. A flywheel rim support having a disc connected an outer diameter of a shaft. Two optimally shaped shell elements connect to the optimally shaped disc at an interface. The interface defines a discontinuity in a meridional slope of said support. A cylindrical shell element connects to the two shell elements. The cylindrical shell element has an outer surface for connecting to the inner surface of the flywheel rim. A flywheel rim casing includes an annular shell connected to the central shaft. The annular shell connects to the flywheel rim. A composite shell surrounds the shaft, annular shell and flywheel rim.

Blake, H.W.

2000-04-04

39

Removable inner turbine shell with bucket tip clearance control  

DOEpatents

A turbine includes a plurality of inner shell sections mounting first and second stage nozzle and shroud portions. The inner shell sections are pinned to an outer containment shell formed of sections to preclude circumferential movement of the inner shell relative to the outer shell and enable thermal expansion and contraction of the inner shell relative to the outer shell. Positive bucket tip clearance control is afforded by passing a thermal medium about the inner shell in heat transfer relation with the shrouds about the first and second stage bucket tips, the thermal medium being provided from a source of heating/cooling fluid independent of the turbine. Access is provided to the rotor and turbine buckets by removing the outer and inner shell sections.

Sexton, Brendan F. (Clifton Park, NY); Knuijt, Hans M. (Niskayuna, NY); Eldrid, Sacheverel Q. (Saratoga Springs, NY); Myers, Albert (Amsterdam, NY); Coneybeer, Kyle E. (Schenectady, NY); Johnson, David Martin (Ballston Lake, NY); Kellock, Iain R. (Clifton Park, NY)

2000-01-01

40

75 FR 54369 - BOEMRE Information Collection Activity: 1010-NEW, Upcoming Projects Considering the Use of Outer...  

Federal Register 2010, 2011, 2012, 2013

...Upcoming Projects Considering the Use of Outer Continental Shelf Sand, Gravel, and Shell...1337(k)(2)) to convey rights to Outer Continental Shelf sand, gravel, and...technology acquisition, expected useful life of capital equipment, discount...

2010-09-07

41

Method to produce large, uniform hollow spherical shells  

DOEpatents

Large, uniform hollow spherical shells are produced by forming uniform size drops of heat decomposable or vaporizable material, evaporating the drops to form dried particles, coating the dried particles with a layer of shell forming material, and heating the composite particles to melt the outer layer and decompose or vaporize the inner particle to form an expanding inner gas bubble which expands the outer layer. By cycling the temperature and pressure on the hollow shells, spherical shells with uniform walls are produced.

Hendricks, Charles D. (Livermore, CA)

1985-01-01

42

Inner and outer ear anatomy  

NSDL National Science Digital Library

Sounds are actually waves from vibrations. The outer ear catches these waves and funnels them down into the inner ear. The waves reach the eardrum and in turn make the eardrum vibrate. Three small bones receive these vibrations next, then a snail shell-shaped structure called the cochlea. The cochlea is filled with liquid, and this liquid stimulates hairs inside the inner ear. The hairs transmit the signal to the auditory nerve where the signal is taken to the brain and processed as sound.

Zina Deretsky (National Science Foundation;)

2006-10-23

43

Wireless Transfer of Electricity in Outer Space  

Microsoft Academic Search

Author offers conclusions from his research of a revolutionary new idea - transferring electric energy in the hard vacuum of outer space wirelessly, using a plasma power cord as an electric cable (wire). He shows that a certain minimal electric currency creates a compressed force that supports the plasma cable in the compacted form. A large energy can be transferred

Alexander Bolonkin

2007-01-01

44

Turbine blade with spar and shell  

SciTech Connect

A turbine blade with a spar and shell construction in which the spar and the shell are both secured within two platform halves. The spar and the shell each include outward extending ledges on the bottom ends that fit within grooves formed on the inner sides of the platform halves to secure the spar and the shell against radial movement when the two platform halves are joined. The shell is also secured to the spar by hooks extending from the shell that slide into grooves formed on the outer surface of the spar. The hooks form a serpentine flow cooling passage between the shell and the spar. The spar includes cooling holes on the lower end in the leading edge region to discharge cooling air supplied through the platform root and into the leading edge cooling channel.

Davies, Daniel O. (Palm City, FL); Peterson, Ross H. (Loxahatchee, FL)

2012-04-24

45

The Outer Limits: English.  

ERIC Educational Resources Information Center

The Quinmester course "The Outer Limits" involves an exploration of unknown worlds, mental and physical, through fiction and nonfiction. Its purpose is to focus attention on the ongoing conquest of the frontiers of the mind, the physical world, and outer space. The subject matter includes identification and investigation of unknown worlds in the…

Tyler, Barbara R.; Biesekerski, Joan

46

The Outer Limits: English.  

ERIC Educational Resources Information Center

|The Quinmester course "The Outer Limits" involves an exploration of unknown worlds, mental and physical, through fiction and nonfiction. Its purpose is to focus attention on the ongoing conquest of the frontiers of the mind, the physical world, and outer space. The subject matter includes identification and investigation of unknown worlds in the…

Tyler, Barbara R.; Biesekerski, Joan

47

Outer Planet Flagship Mission  

Microsoft Academic Search

Studies for Outer Planet Missions have been ongoing for many years, but in 2007 NASA commissioned four specific studies to be considered for further examination; the Europa Explorer, Titan Explorer, Enceladus Mission and Jupiter Science Orbiter. During the same time frame ESA invited Outer Planet proposals under the Cosmic Vision call. Two were submitted, TandEm and LaPlace, which focused on

James Cutts; C. Niebur; L. Dudzinski; M. Coradini; J. Lebreton

2008-01-01

48

Outer Planet Flagship Missions  

Microsoft Academic Search

Studies for Outer Planet Missions have been ongoing for many years, but in 2007 NASA commissioned four specific studies to be considered for further examination; the Europa Explorer, Titan Explorer, Enceladus Mission and Jupiter Science Orbiter. During the same time frame ESA invited Outer Planet proposals under the Cosmic Vision call. Two were submitted, TandEM and LaPlace, which focused on

C. Niebur; L. Dudzinski; M. Coradini; J. Lebreton; J. A. Cutts

2008-01-01

49

Outer planet satellites  

Microsoft Academic Search

Recent findings on the outer-planet satellites are presented, with special consideration given to data on the rheologic properties of ice on icy satellites, the satellite surfaces and exogenic processes, cratering on dead cratered satellites, volcanism, and the interiors of outer-planet satellites. Particular attention is given to the state of Titan's surface and the properties of Triton, Pluto, and Charon.

Paul M. Schenk

1991-01-01

50

Role of shell crossing on the existence and stability of trapped matter shells in spherical inhomogeneous {Lambda}-CDM models  

SciTech Connect

We analyze the dynamics of trapped matter shells in spherically symmetric inhomogeneous {Lambda}-CDM models. The investigation uses a generalized Lemaitre-Tolman-Bondi description with initial conditions subject to the constraints of having spatially asymptotic cosmological expansion, initial Hubble-type flow, and a regular initial density distribution. We discuss the effects of shell crossing and use a qualitative description of the local trapped matter shells to explore global properties of the models. Once shell crossing occurs, we find a splitting of the global shells separating expansion from collapse into, at most, two global shells: an inner and an outer limit trapped matter shell. In the case of expanding models, the outer limit trapped matter shell necessarily exists. We also study the role of shear in this process, compare our analysis with the Newtonian framework, and give concrete examples using density profile models of structure formation in cosmology.

Le Delliou, Morgan; Mena, Filipe C.; Mimoso, Jose P. [Instituto de Fisica Teorica UAM/CSIC, Facultad de Ciencias, C-XI, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Centro de Matematica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Departamento de Fisica, Faculdade de Ciencias da Universidade de Lisboa, Centro de Astronomia e Astrofisica, Universidade de Lisboa, Campo Grande, Edificio C8 P-1749-016, Lisboa (Portugal)

2011-05-15

51

Misfit Strain Relaxation Mechanisms in Core/Shell Nanowires  

NASA Astrophysics Data System (ADS)

In the past decade, core/shell nanowires (NWs) have attracted much attention due to the broad variety of potential applications of these structures in future nanoelectronic and nanophotonic devices. Because of the lattice mismatch between the core and shell materials, crystal dislocations often form to relax the mismatch strains. In this article, we propose a relaxation mechanism for the misfit strains generated in the core/shell NWs, in which lattice dislocations nucleate from the outer surfaces and then propagate to the core/shell interface. An analytical model is developed to predict the critical shell thickness corresponding to defect-free core/shell NWs with respect to the growth direction.

Chu, Haijian; Zhou, Caizhi; Wang, Jian; Beyerlein, Irene J.

2012-10-01

52

Outer Solar System Nomenclature.  

National Technical Information Service (NTIS)

The Principal Investigator's responsibilities on this grant fell into two categories according to his participation. In the nomenclature work of the International Astronomical Union (IAU), Owen is chair of the Task Group for the Outer Solar System. He is ...

T. C. Owen

1998-01-01

53

Axes in Outer Space  

Microsoft Academic Search

We develop a notion of axis in the Culler--Vogtmann outer space X_r of a finite rank free group F_r, with respect to the action of a nongeometric, fully irreducible outer automorphism phi. Unlike the situation of a loxodromic isometry acting on hyperbolic space, or a pseudo-Anosov mapping class acting on Teichmuller space, X_r has no natural metric, and phi seems

Michael Handel; Lee Mosher

2006-01-01

54

Outer planet satellites  

SciTech Connect

Recent findings on the outer-planet satellites are presented, with special consideration given to data on the rheologic properties of ice on icy satellites, the satellite surfaces and exogenic processes, cratering on dead cratered satellites, volcanism, and the interiors of outer-planet satellites. Particular attention is given to the state of Titan's surface and the properties of Triton, Pluto, and Charon. 210 refs.

Schenk, P.M. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

55

Sr heterogeneity in textit{Arctica islandica} shells and the potential use of Sr/Ca ratios as paleotemperature proxies  

NASA Astrophysics Data System (ADS)

Quantifiable paleotemperature data can help to verify predictions made by numerical climate models. Traditionally, paleotemperature estimates are based on ?18O values of biogenic hard parts. However, oxygen isotope values not only reflect changes in ambient temperature, but also changes in ?18Owater, i.e. driven by freshwater influx, evaporation etc. Information regarding the ?18Owater value of past environments is limited for the geological past. The validity of published ?18O paleotemperature data can be tested using element-to-calcium ratios of bivalve shells such as the long-lived ocean quahog, Arctica islandica. Preliminary investigations suggest that Sr/Ca ratios of this species may provide more reliable paleotemperature data. However, contemporaneously deposited shell portions within the outer shell layer demonstrate at least a 30% variability in the Sr/Ca value. This study presents Sr/Ca ratios measured by ICP-OES wet-chemical analyses. Significantly different distributions of Sr/Ca ratios were recorded from the shell surface (over 1330 ppm), through the interior (850 ppm) and to the inner shell surface (1860 ppm). Furthermore, this study showed that different shell crystal fabrics incorporate different amounts of Sr into the CaCO3 lattice of the A. islandica shell. Disparate Sr distribution could potentially be explained either by postdepositional diagenetic processes or syndepositional processes during biomineralization (i.e. different amounts of Sr incorporated into the shell). Understanding the mechanism of the observed Sr heterogeneity is essential if Sr/Ca ratios are to be used confidently in paleotemperature reconstructions.

Radermacher, Pascal; Schöne, Bernd R.; Nunn, Elizabeth V.; Zengjie, Zhang

2010-05-01

56

DIFFUSION OF PROTONS IN THE OUTER RADIATION BELT  

Microsoft Academic Search

The diffusion of protons in the outer radiation belt due to violation of the third adiabatic invariant has been examined. The particular mechanism studied is one in which variations in the intensity of the solar wind produce magnetic disturbances causing motion of particles between L shells. A Fokker-Planck diffusion equation is used with terms describing Coulomb energy degradation and charge-exchange

M. P. Nakada; G. D. Mead

1965-01-01

57

Biomineral repair of abalone shell apertures.  

PubMed

The shell of the gastropod mollusc, abalone, is comprised of nacre with an outer prismatic layer that is composed of either calcite or aragonite or both, depending on the species. A striking characteristic of the abalone shell is the row of apertures along the dorsal margin. As the organism and shell grow, new apertures are formed and the preceding ones are filled in. Detailed investigations, using electron backscatter diffraction, of the infill in three species of abalone: Haliotis asinina, Haliotis gigantea and Haliotis rufescens reveals that, like the shell, the infill is composed mainly of nacre with an outer prismatic layer. The infill prismatic layer has identical mineralogy as the original shell prismatic layer. In H. asinina and H. gigantea, the prismatic layer of the shell and infill are made of aragonite while in H. rufescens both are composed of calcite. Abalone builds the infill material with the same high level of biological control, replicating the structure, mineralogy and crystallographic orientation as for the shell. The infill of abalone apertures presents us with insight into what is, effectively, shell repair. PMID:23707541

Cusack, Maggie; Guo, Dujiao; Chung, Peter; Kamenos, Nicholas A

2013-05-24

58

Thickness Constraints on the Icy Shells of the Galilean Satellites from a Comparison of Crater Shapes.  

National Technical Information Service (NTIS)

A thin outer ice shell on Jupiter's large moon Europa would imply easy exchange between the surface and any organic or biotic material in its putative subsurface ocean. The thickness of the outer ice shell is poorly constrained, however, with model-depend...

P. M. Schenk

2002-01-01

59

Thermal coupling between the mantle, outer core and inner core: an experimental model  

Microsoft Academic Search

Thermal coupling between the mantle and the outer core has been proposed based upon the correlation between the patterns of stationary geomagnetic field and the seismic heterogeneity of the lower mantle (Bloxham and Gubbins, 1987). We have studied how such thermal heterogeneity can affect the outer core flow, using laboratory experiments in a rapidly rotating hemispherical shells (Sumita and Olson,

I. Sumita

2007-01-01

60

Law in Outer Space.  

ERIC Educational Resources Information Center

Provides an overview of the current practice and fascinating future of legal issues involved in outer space exploration and colonization. Current space law, by necessity, addresses broad principles rather than specific incidents. Nonetheless, it covers a variety of issues including commercial development, rescue agreements, object registration,…

Schmidt, William G.

1997-01-01

61

Law in Outer Space.  

ERIC Educational Resources Information Center

|Provides an overview of the current practice and fascinating future of legal issues involved in outer space exploration and colonization. Current space law, by necessity, addresses broad principles rather than specific incidents. Nonetheless, it covers a variety of issues including commercial development, rescue agreements, object registration,…

Schmidt, William G.

1997-01-01

62

Tides on Europa, and the thickness of Europa's icy shell  

Microsoft Academic Search

It has been shown previously that measurements of tides on Jupiter's moon Europa can be used to determine whether there is a liquid ocean beneath this moon's icy outer shell. In this paper we examine the further possibility of constraining the thickness of the icy shell in the case where a liquid ocean exists, by combining measurements of tidal gravity

J. M. Wahr; M. T. Zuber; D. E. Smith; J. I. Lunine

2006-01-01

63

The microindentation behavior of several mollusk shells  

SciTech Connect

An investigation of the relationship between structure and mechanical behavior is reported for mollusk shells employing foliated, nacreous, and crossed-lamellar structures by microindentation in the Knoop and Vickers geometries. Indentation damage zones develop crack systems that reflect the micro-architecture. For the crosed-lamellar structure, the system of cracks about the indentation normally developed in a brittle material is suppressed. Previous reports that shells are harder than the corresponding minerals, calcite and aragonite, are confirmed, but it is found that this effect can be strongly dependent on orientation. This anomalous hardness is not an artifact of the indentation test technique, since scratch tests confirm the relative hardness of shell over the mineral. It is suggested that microstructural organization is of central importance in producing this hardness, as opposed to intrinsic properties of the mineral or matrix phases. 17 refs., 6 figs., 1 tab.

Laraia, V.J.; Heuer, A.H. (Case Western Reserve Univ., Cleveland, OH (USA). Dept. of Materials Science and Engineering)

1990-01-01

64

Calculation Cover Sheet, Waste Package Outer barrier stress Due to Thermal Exspansion with VArious Barrier Gap Sizes, CAL-EBS-ME-000011, Revision 00.  

National Technical Information Service (NTIS)

The objective of this activity is to determine the tangential stresses of the outer shell, due to uneven thermal expansion of the inner and outer shells of the current waste package (WP) designs. Based on the results of the calculation Waste Package Barri...

M. Lewis Z. Ceylan S. M. Bennett

2005-01-01

65

Synthesis of monodisperse hollow carbon nanocapsules by using protective silica shells.  

PubMed

Monodisperse hollow carbon nanocapsules (<200 nm) with mesoporous shells were synthesized by coating their outer shells with silica to prevent aggregation during their high-temperature annealing. Monodispersed silica nanoparticles were used as starting materials and octadecyltrimethoxysilane (C18TMS) was used as a carbon source to create core-shell nanostructures. These core-shell nanoparticles were coated with silica on their outer shell to form a second shell layer. This outer silica shell prevented aggregation during calcination. The samples were characterized by TEM, SEM, dynamic light scattering (DLS), UV/Vis spectroscopy, and by using the Brunauer-Emmett-Teller (BET) method. The as-synthesized hollow carbon nanoparticles exhibited a high surface area (1123 m(2) g(-1)) and formed stable dispersions in water after the pegylation process. The drug-loading and drug-release properties of these hollow carbon nanocapsules were also investigated. PMID:23345002

Quan, Bo; Nam, Gi-Eun; Choi, Hyuck Jae; Piao, Yuanzhe

2013-01-23

66

Vital outer continental shelf  

Microsoft Academic Search

The US Continental Shelf has already yielded 5.4 billion barrels of crude oil and 49.2 trillion cubic feet of natural gas, but geologists estimate that 83 billion barrels of oil and 594 trillion cubic feet of gas remain to be tapped. The Outer Continental Shelf lies beyond the three-mile state jurisdiction and is administered by the US government, except in

2009-01-01

67

Duurzaamheid Buitenhuid Beton (Durability of Outer Shell of Concrete).  

National Technical Information Service (NTIS)

While a great deal of work has been done to improve the appearance of concrete, in practice the results are to often inadequate. There are numerous examples of concrete which has been affected by pollution, algae growth, frost damage or chemical corrosion...

E. J. Apol C. Hansen R. F. M. Bakker J. M. J. M. Bijen G. van der Duim

1981-01-01

68

Core-shell nanostructured catalysts.  

PubMed

Novel nanotechnologies have allowed great improvements in the syn-thesis of catalysts with well-controlled size, shape, and surface properties. Transition metal nanostructures with specific sizes and shapes, for instance, have shown great promise as catalysts with high selectivities and relative ease of recycling. Researchers have already demonstrated new selective catalysis with solution-dispersed or supported-metal nanocatalysts, in some cases applied to new types of reactions. Several challenges remain, however, particularly in improving the structural stability of the catalytic active phase. Core-shell nanostructures are nanoparticles encapsulated and protected by an outer shell that isolates the nanoparticles and prevents their migration and coalescence during the catalytic reactions. The synthesis and characterization of effective core-shell catalysts has been at the center of our research efforts and is the focus of this Account. Efficient core-shell catalysts require porous shells that allow free access of chemical species from the outside to the surface of nanocatalysts. For this purpose, we have developed a surface-protected etching process to prepare mesoporous silica and titania shells with controllable porosity. In certain cases, we can tune catalytic reaction rates by adjusting the porosity of the outer shell. We also designed and successfully applied a silica-protected calcination method to prepare crystalline shells with high surface area, using anatase titania as a model system. We achieved a high degree of control over the crystallinity and porosity of the anatase shells, allowing for the systematic optimization of their photocatalytic activity. Core-shell nanostructures also provide a great opportunity for controlling the interaction among the different components in ways that might boost structural stability or catalytic activity. For example, we fabricated a SiO2/Au/N-doped TiO2 core-shell photocatalyst with a sandwich structure that showed excellent catalytic activity for the oxidation of organic compounds under UV, visible, and direct sunlight. The enhanced photocatalytic efficiency of this nanostructure resulted from an added interfacial nonmetal doping, which improved visible light absorption, and from plasmonic metal decoration that enhanced light harvesting and charge separation. In addition to our synthetic efforts, we have developed ways to evaluate the accessibility of reactants to the metal cores and to characterize the catalytic properties of the core-shell samples we have synthesized. We have adapted infrared absorption spectroscopy and titration experiments using carbon monoxide and other molecules as probes to study adsorption on the surface of metal cores in metal oxide-shell structures in situ in both gas and liquid phases. In particular, the experiments in solution have provided insights into the ease of diffusion of molecules of different sizes in and out of the shells in these catalysts. PMID:23268644

Zhang, Qiao; Lee, Ilkeun; Joo, Ji Bong; Zaera, Francisco; Yin, Yadong

2012-12-26

69

Building Atoms Shell by Shell.  

ERIC Educational Resources Information Center

|Describes an atom-building activity where students construct three-dimensional models of atoms using a styrofoam ball as the nucleus and pom-poms, gum drops, minimarshmallows, or other small items of two different colors to represent protons and neutrons attached. Rings of various sizes with pom-poms attached represent electron shells and…

Sussman, Beverly

1993-01-01

70

Energetic particle drift motions in the outer dayside magnetosphere  

SciTech Connect

Models of the geomagnetic field predict that within a distance of approximately one earth radius inside the dayside magnetopause, magnetic fields produced by the Chapman-Ferraro magnetopause currents create high-latitude minimum-B ''pockets'' in the geomagnetic field. Drift-shell branching caused by the minimum-B pockets is analyzed and interpreted in terms of an adiabatic shell branching and rejoining process. We examine the shell-branching process for a static field in detail, using the Choe-Beard 1974 magnetospheric magnetic field model. We find that shell branching annd rejoining conserves the particle mirror field B/sub M/, the fieldline integral invariant I, and the directional electron flux j. We determine the spatial extent of the stable trapping regions for the Choe-Beard model. We develop an adiabatic branching map methodology which completely identifies and describes the location of shell-branching points and the adiabatic trajectories of particles on branched shells, for any model field. We employ the map to develop synthetic pitch angle distributions near the dayside magnetopause by adiabatically transforming observed midnight distributions to the dayside. We find that outer dayside lines contain particles moving on branched and unbranched shells, giving rise to distinctive pitch angle distribution features. We find a good correlation between the pitch angles which mark the transition from branched to unbranched shells in the model, and the distinctive features of the OGO-5 distributions. In the morning sector, we observe large flux changes at critical pitch angles which correspond to B-pocket edges in the model. Measurements on inbound passes in the afternoon sector show first the adiabatic particle shadow, then the arrival of fluxes on rejoined shells, then fluxes on unbranced shells - in accord with model predictions. 204 refs., 138 figs., 2 tabs.

Buck, R.M.

1987-12-01

71

Adsorption of the aurocyanide, Au ( CN ) 2 - complex on granular activated carbons derived from macadamia nut shells – A preliminary study  

Microsoft Academic Search

In this study, waste macadamia nut shells were investigated for potential use as a hard organic precursor for the production of a granular activated carbon material. The processing of the macadamia shells commenced with the carbonised of the shells under a nitrogen atmosphere. This was followed by the physical activation of the shells under a carbon dioxide atmosphere, which was

Gerrard Eddy Jai Poinern; Gamini Senanayake; Nikunj Shah; Xuan N. Thi-Le; Gordon M. Parkinson; Derek Fawcett

2011-01-01

72

Shell worlds  

NASA Astrophysics Data System (ADS)

The traditional concept of terraforming assumes ready availability of candidate planets with acceptable qualities: orbiting a star in its "Goldilocks zone", liquid water, enough mass, years longer than days, magnetic field, etc. But even stipulating affordable interstellar travel, we still might never find a good candidate elsewhere. Whatever we found likely would require centuries of heavy terraforming, just as Mars or Venus would here. Our increasing appreciation of the ubiquity of life suggests that any terra nova would already possess it. We would then face the dilemma of introducing alien life forms (us, our microbes) into another living world. Instead, we propose a novel method to create habitable environments for humanity by enclosing airless, sterile, otherwise useless planets, moons, and even large asteroids within engineered shells, which avoids the conundrum. These shells are subject to two opposing internal stresses: compression due to the primary's gravity, and tension from atmospheric pressure contained inside. By careful design, these two cancel each other resulting in zero net shell stress. Beneath the shell an Earth-like environment could be created similar in almost all respects to that of Home, except for gravity, regardless of the distance to the sun or other star. Englobing a small planet, moon, or even a dwarf planet like Ceres, would require astronomical amounts of material (quadrillions of tons) and energy, plus a great deal of time. It would be a quantum leap in difficulty over building Dyson Dots or industrializing our solar system, perhaps comparable to a mission across interstellar space with a living crew within their lifetime. But when accomplished, these constructs would be complete (albeit small) worlds, not merely large habitats. They could be stable across historic timescales, possibly geologic. Each would contain a full, self-sustaining ecology, which might evolve in curious directions over time. This has interesting implications for SETI as well.

Roy, Kenneth I.; Kennedy, Robert G., III; Fields, David E.

2013-02-01

73

A role of magnetopause shadowing on relativistic electron loss of the outer radiation belt  

NASA Astrophysics Data System (ADS)

It has been known that relativistic electron fluxes rapidly decrease associate with solar wind disturbances. If the magnetopause shadowing (MPS) is effective for decreases of the energetic electrons of the outer belt, close correlations are expected between the position of the outer edge of the outer belt and solar wind parameters such as the dynamic pressure and IMF Bz. In order to clarify a role of the MPS on electron losses of the outer belt, we statistically investigate the dependence of the outer edge position of the outer belt on the solar wind parameters and the magnetopause distance using the THEMIS/SST and GOES data. As a preliminary result, it is found that solar wind dynamic pressure and southward IMF Bz tend to have large value during the events. Moreover, we show that there is a correlation between the L-shell of the outer edge of the outer belt and the magnetopause location. These statistical results are mostly consistent with previous simulation and observational studies, which indicated that the MPS efficiently works for the loss of the energetic electrons of the outer part of the outer belt. Therefore, we suggest that the MPS is effective for losses of energetic electrons of the outer part of the outer belt.

Matsumura, C.; Miyoshi, Y.; Seki, K.; Saito, S.; Angelopoulos, V.; McFadden, J.; Larson, D. E.

2010-12-01

74

CORNER OF SUBPILE ROOM: NORTH AND EAST SIDES. STEEL OUTER ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

CORNER OF SUBPILE ROOM: NORTH AND EAST SIDES. STEEL OUTER SHELL HAS BEEN AFFIXED. SIGN SAYS "HERRICK IRON WORKS STEEL, OAKLAND, CALIFORNIA." NOTE CONDUIT FOR FUTURE INSTRUMENTATION. TOP OF STEEL CASE WILL BE LEVEL WITH BASEMENT CEILING. CAMERA FACES SOUTHEAST. INL NEGATIVE NO. 734. Unknown Photographer, 10/6/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

75

Frame ultimate stiffness in the problems on the strength of shell  

NASA Astrophysics Data System (ADS)

The elastic state of thin cylindric shells which are constructively orthotropic is studied. The conditions of hardness of circle shpangouts are considered. According to computing and natural experiments on St3 and Kh22N6T steels the limit values of hardness so that shpangouts become either absolutely hard or absolutely soft for the given shell are stated. It is shown that for axially symmetric deformations it is required to take into account the elasticity of shpangouts. It is possible to use the absolutely hard shpangout idea for non-axially symmetric elasticity of a shell.

Antonenko, E. V.

1994-07-01

76

Elastic ice shells of synchronous moons: Implications for cracks on Europa and non-synchronous rotation of Titan  

Microsoft Academic Search

A number of synchronous moons are thought to harbor water oceans beneath their outer ice shells. A subsurface ocean frictionally decouples the shell from the interior. This has led to proposals that a weak tidal or atmospheric torque might cause the shell to rotate differentially with respect to the synchronously rotating interior. Applications along these lines have been made to

Peter M. Goldreich; Jonathan L. Mitchell

2010-01-01

77

Waste Package Outer Barrier Stress Due to Thermal Expansion with Various Barrier Gap Sizes  

SciTech Connect

The objective of this activity is to determine the tangential stresses of the outer shell, due to uneven thermal expansion of the inner and outer shells of the current waste package (WP) designs. Based on the results of the calculation ''Waste Package Barrier Stresses Due to Thermal Expansion'', CAL-EBS-ME-000008 (ref. 10), only tangential stresses are considered for this calculation. The tangential stresses are significantly larger than the radial stresses associated with thermal expansion, and at the WP outer surface the radial stresses are equal to zero. The scope of this activity is limited to determining the tangential stresses the waste package outer shell is subject to due to the interference fit, produced by having two different shell coefficients of thermal expansions. The inner shell has a greater coefficient of thermal expansion than the outer shell, producing a pressure between the two shells. This calculation is associated with Waste Package Project. The calculations are performed for the 21-PWR (pressurized water reactor), 44-BWR (boiling water reactor), 24-BWR, 12-PWR Long, 5 DHLW/DOE SNF - Short (defense high-level waste/Department of Energy spent nuclear fuel), 2-MCO/2-DHLW (multi-canister overpack), and Naval SNF Long WP designs. The information provided by the sketches attached to this calculation is that of the potential design for the types of WPs considered in this calculation. This calculation is performed in accordance with the ''Technical Work Plan for: Waste Package Design Description for SR (Ref.7). The calculation is documented, reviewed, and approved in accordance with AP-3.12Q, Calculations (Ref.1).

M. M. Lewis

2001-11-27

78

Outer Planet Assessment Group (OPAG) Recommended Exploration Strategy for the Outer Planets 2013-2022  

NASA Astrophysics Data System (ADS)

The Outer Solar System provides critical clues to how solar systems form and evolve, how planetary systems become habitable, and how life has evolved in our solar system. NASA's Outer Planets Assessment Group (OPAG) was established to identify scientific priorities and pathways for Outer Solar System exploration. Fundamental new discoveries are best made with a mixture of mission sizes that includes large (flagship) missions, and medium-sized and smaller-sized (as practical) missions, along with vigorous support for basic research, data analysis, and technology development — a balanced strategy most efficiently implemented as an Outer Planets Exploration Program. Missions to the Outer Solar System are major undertakings, requiring large and expensive launch vehicles, long mission durations, highly reliable (frequently radiation hard) and autonomous spacecraft, and radioisotope power sources in most cases. OPAG has recommended to the US National Research Council Planetary Science Decadal Survey to explore the possibilities for ‘small flagship' class missions to be considered, providing a greater range of choice and capabilities in the mix to balance program size and science return. With the Galileo mission concluded, the Cassini equinox mission in progress, and Juno in development, OPAG has strongly endorsed the competitive selection by NASA of the Jupiter Europa Orbiter (JEO) as the next Outer Planets Flagship and as part of the Europa Jupiter System Mission (EJSM) with ESA, a collaboration that includes a Ganymede orbiter and an increased focus on Jupiter science; OPAG has strongly recommended support of JEO and EJSM in the Decadal Survey. In addition, OPAG has strongly endorsed approval by NASA of the Cassini Solstice Mission, including the Juno-like end-of-mission scenario, given the likely phenomenal return on investment. OPAG also advocates the need for a focused technology program for the next Outer Planet Flagship Mission after EJSM, in order to be ready for a launch in the mid-2020s. In this regard, a return to Titan and Enceladus is the highest priority. Technologies that require long-term investment for missions beyond the next decade should also be considered. Medium-sized, New Frontiers class missions that should be considered in the interim include (but not in priority order) probe missions to the giant planets, an Io observer, a Neptune/Triton/KBO rendezvous, a Titan in-situ explorer or probe, and a Uranus orbiter, and OPAG recommended to the Decadal Survey that these be studied, costed, and if deemed feasible added to the approved New Frontiers mission set. Full details can be accessed through the OPAG website at http://www.lpi.usra.edu/decadal/opag/index.html.

McKinnon, William B.; Steering Committee, Opag; Planets Community, Outer

2010-05-01

79

The 4 K outer cryostat for the CUORE experiment: Construction and quality control  

NASA Astrophysics Data System (ADS)

The external shell of the CUORE cryostat is a large cryogen-free system designed to host the dilution refrigerator and the bolometers of the CUORE experiment in a low radioactivity environment. The three vessels that form the outer shell were produced and delivered to the Gran Sasso underground Laboratories in July 2012. In this paper, we describe the production techniques and the validation tests done at the production site in 2012.

Alessandria, F.; Biassoni, M.; Ceruti, G.; Chiarini, A.; Clemenza, M.; Cremonesi, O.; Datskov, V.; Dossena, S.; Faverzani, M.; Ferri, E.; Nucciotti, A.; Perego, M.; Previtali, E.; Sisti, M.; Taffarello, L.; Terranova, F.

2013-11-01

80

Nondipole effects in molecular nitrogen valence shell photoionization.  

SciTech Connect

Nondipole photoelectron parameters {zeta} have been obtained experimentally for the outer-valence 3{sigma}{sub g}, 1{pi}{sub {mu}} and 2{sigma}{sub {mu}} shells in molecular nitrogen from threshold to {approx} 200 eV photon energy. Significant nondipole effects are observed even in the immediate threshold regions of these valence-shell distributions. The results of preliminary calculations for the 3{sigma}{sub g} and 2{sigma}{sub {mu}} clarify the origins of the observed features in terms of contributing molecular symmetry channels. Theory and experiment are in excellent accord, suggesting that the large nondipole effects previously observed in atoms and the K-shells of molecules can also appear at low photon energies in the outer-valence shells of molecules.

Hemmers, O.; Guillemin, R.; Rolles, D.; Wolska, A.; Lindle, D. W.; Kanter, E. P.; Kraessig, B.; Southworth, S. H.; Wehlitz, R.; Zimmermann, B.; McKoy, V.; Langhoff, P. W.; Chemistry; Univ. of Nevada; LBNL; Univ. of Wisconsin; Max Planck Inst. for the Physics of Complex Systems; California Inst. of Tech.; Univ. of California

2005-01-01

81

Mussel Shell Evaluation as Bioindicator For Heavy Metals  

NASA Astrophysics Data System (ADS)

Recently, in Brazil, it has appeared a new and unusual ``plague'' in lazer and commercial fishing. It is caused by the parasitic larval phase of certain native bivalve mollusks of fresh water known as ``Naiades'' and its involves the presence of big bivalve of fresh water, mainly Anodontites trapesialis, in the tanks and dams of the fish creation. These bivalve mollusks belong to the Unionoida Order, Mycetopodidae Family. The objective of the present work was to analyze the shells of these mollusks to verify the possibility of use as bioindicators for heavy metals in freshwater. The mollusks shells were collected in a commercial fishing at Londrina-PR. A qualitative analysis was made to determine the chemical composition of the shells and verify a possible correlation with existent heavy metals in the aquatic environment. In the inner part of the shells were identified the elements Ca, P, Fe, Mn and Sr and in the outer part were identified Ca, P, Fe, Mn, Sr and Cu. The Ca ratio of the outer part by inner part of the analyzed shells is around of 1, as expected, because Ca is the main compound of mollusks shells. The ratio of P, Fe, Mn, and Sr to the Ca were constant in all analyzed shells, being close to 0.015. The ratio Cu/Ca varied among the shells, showing that this mollusk is sensitive to concentration of this element in the aquatic environment.

Andrello, Avacir Casanova; Lopes, Fábio; Galva~O, Tiago Dutra

2010-05-01

82

Can the Ice I Shells of Icy Satellites Convect?  

Microsoft Academic Search

It has been recently been argued by Ruiz (Nature 412, 409-411) that the dominant non-Newtonian creep mechanisms of water ice make the ice shell above Callisto's ocean stable against solid-state convective overturn, based on the convective scaling relationships of V.S. Solomatov. The argument is actually broader, and applies to all radiogenically heated ice I shells in the outer solar system,

W. B. McKinnon

2001-01-01

83

Distributed neural signals on parabolic cylindrical shells  

NASA Astrophysics Data System (ADS)

Parabolic cylindrical shells are commonly used as key components in communication antennas, space telescopes, solar collectors, etc. This study focuses on distributed modal neural sensing signals on a flexible simply-supported parabolic cylindrical shell panel. The parabolic cylindrical shell is fully laminated with a piezoelectric layer on its outer surface and the piezoelectric layer is segmented into infinitesimal elements (neurons) to investigate the microscopic distributed neural sensing signals. Since the dominant vibration component of the shell is usually the transverse oscillation, a new transverse mode shape function is defined. Two shell cases, i.e., the ratio of the meridian height to the half span distance of a parabola at 1:4 (shallow) and 1:1 (deep), are studied to reveal the curvature effect to the neural sensing signals. Studies suggest that the membrane signal component dominates for lower natural modes and the bending signal component dominates for higher natural modes. The meridional membrane and bending signal components are mostly concentrated on the high-curvature areas, while the longitudinal bending component is mostly concentrated on the relatively flat areas. The concentration behavior becomes more prominent as the parabolic cylindrical shell deepens, primarily resulting from the enhanced membrane effect due to the increased curvature.

Hu, S. D.; Li, H.; Tzou, H. S.

2013-06-01

84

FIRST 100 T NON-DESTRUCTIVE MAGNET OUTER COIL SET  

SciTech Connect

The controlled power outer coil set of the first 100 T non-destructive (100 T ND) magnet is described. This magnet will be installed as part of the user facility research equipment at the National High Magnetic Field laboratory (NHMFL) Pulsed Field Facility at Los Alamos National Laboratory. The 100 T ND controlled power outer coil set consists of seven nested, mechanically independent externally reinforced coils. These coils, in combination, will produce a 47 T platform field in a 225-mm diameter bore. Using inertial energy storage a synchronous motor/generator provides ac power to a set of seven ac-dc converters rated at 64 MW/80 MVA each. These converters energize three independent coil circuits to create 170 MJ of field energy in the outer coil set at the platform field of 47 T. Each coil consists of a multi-layer winding of high strength conductor supported by an external high strength stainless steel shell. Coils with the highest magnetic loads will utilize a reinforcing shell fabricated from highly cold worked 301 stainless steel strip. The autofrettage conditioning method will be used to pre-stress the coils and thereby limit conductor and reinforcement strains to the elastic range. The purpose of pre-stressing the coils is to attain a design life of 10,000 full field pulses. The operation and conditioning of the coil set will be described along with special features of its design, magnetic and structural analyses and construction.

J. BACON; A. BACA; ET AL

1999-09-01

85

Paclitaxel and suramin-loaded core\\/shell microspheres in the treatment of brain tumors  

Microsoft Academic Search

This work presents a modified method, namely coaxial electrohydrodynamic atomization, for the preparation of microspheres with distinct core\\/shell structures. This allows the encapsulation of two drugs with different characteristics in hydrophilic properties in one single step. Variation of ratios between outer flow and inner flow produces polymer microspheres with different core\\/shell ratios, and consequently results in variable release rates of

Hemin Nie; Yilong Fu; Chi-Hwa Wang

2010-01-01

86

Impact dynamics of metal foam shells for motorcycle helmets: Experiments & numerical modeling  

Microsoft Academic Search

To reduce the weight of motorcycle helmet, metal foam for outer shell in place of conventional thermoplastics was tested. The dynamic behaviour of this new helmet was studied through experiments and numerical modeling. Open-face motorcycle helmets were designed with metal foam shell and impact experiments were performed with these helmets fitted on a headform. A finite element model was developed

P. K. Pinnoji; P. Mahajan; N. Bourdet; C. Deck; R. Willinger

2010-01-01

87

Buckling of axially compressed thin cylindrical shells with functionally graded middle layer  

Microsoft Academic Search

Buckling of a simply supported three-layer circular cylindrical shell under axial compressive load is studied. The inner and outer layers of the shell are comprised of the same homogeneous and isotropic material, and the middle layer is made of an isotropic functionally graded (FG) material whose Young's modulus varies either affinely or parabolically in the thickness direction from its value

Shi-Rong Li; R. C. Batra

2006-01-01

88

On structural optimization of composite shell structures using a discrete constitutive parametrization  

Microsoft Academic Search

In this article a novel method for structural optimization of laminated composite shell structures such as wind turbine blades is presented. The outer shape of a wind turbine blade is typically determined by aerodynamic considerations and therefore not subject to change. Furthermore, the thicknesses of the shell structures are also considered fixed. The design objective is chosen to be a

Erik Lund; Jan Stegmann

2005-01-01

89

Variational formulation of a three-dimensional surface-related solid-shell finite element  

Microsoft Academic Search

The solution of structural analysis problems, especially of shell structures, demands an efficient numerical solution strategy.\\u000a Since unilateral contact problems are investigated, the shell model is formulated with respect to one of the outer surfaces,\\u000a i.e., the shell formulation is surface-related. In particular, the investigation of textile reinforced strengthening layers\\u000a (Brameshuber (ed.) in State-of-the-Art Report of RILEM Technical Commitee 201—TRC,

Rainer Schlebusch; Bernd W. Zastrau

2009-01-01

90

A split in the outer radiation belt by magnetopause shadowing  

NASA Astrophysics Data System (ADS)

We developed Geospace Environment Modeling System for Integrated Studies - Radiation Belts (GEMSIS-RB) code at Nagoya University, which is a relativistic test particle simulation code in the terrestrial magnetosphere. The GEMSIS-RB code uses time-varying magnetic field calculated from Tsyganenko model (TS05) with observed solar wind data and the Dst index, and simulates time evolution of the outer radiation belt in the magnetic field. In this study GEMSIS-RB calculations focused on drift loss of relativistic electrons by magnetopause shadowing (MPS). A split was found in the outer radiation belt after MPS occurs. Isolated electrons outside of the split have a narrow pitch angle distribution around 90 degree and are confined to a narrow range of the L-shell. The existence of the isolated electrons depends on the large geomagnetic tilt angle. These findings indicate that the split can be seen during the summer and winter after MPS occurs. The GEMSIS-RB calculations suggest that this split in the outer radiation belt is evidence that MPS actually causes the loss of the outer radiation belt.

Saito, S.; Miyoshi, Y.; Seki, K.

2009-12-01

91

Viscosity of Earth's Outer Core  

NASA Astrophysics Data System (ADS)

The viscosity of Earth's outer liquid core is a fundamental property of great importance in modelling Earth's magnetic field and in many other branches of geophysics and geochemistry. Accurate measurements of viscosity in the F-layer at the bottom of the outer core are provided by the reduction of rotational splitting of the two equatorial translational modes of the inner core, observed with a network of superconducting gravimeters. Independent values are given by the prograde and retrograde modes which differ by about 10%, with a mean value of 1.243× 1011 Pa· s. At the top of the outer core, the viscosity has been measured by the free decays found, for both the retrograde and prograde Free Core Nutations, in the VLBI nutation series provided by Goddard Space Flight Center and the United States Naval Observatory. The four values range just over a factor of two, with a mean value of 2,448 Pa· s. Recently, viscosities ranging from 1011 Pa· s at the bottom of the liquid outer core to 102 Pa· s at the top have been found by Arrhenius extrapolation of laboratory measurements (Brazhkin, JETP Lett. 68, 502, 1998). We report here the results of a similar extrapolation along the melting temperature curve between our measured boundary values to obtain a viscosity profile for the entire outer liquid core.

Palmer, A.; Smylie, D. E.

2006-05-01

92

Probing the Outer Galaxy Halo  

NASA Astrophysics Data System (ADS)

We propose to obtain GHRS 15 km/s resolution G160M integrations of highly ionized gas absorption (N V and CIV) toward PKS2155-304 and NGC5548 in order to continue our HST program to study highly ionized gas in the unexplored outer Galactic halo. The spectral integrations are planned to also provide important low ionization measurements of absorption by Mg II, S II, and Si II. The data will be used to study such questions as: What are the physical properties of gas in the outer Galaxy halo? Does the Galaxy have a highly ionized outer boundary? What are the ionization processes occurring in the outer Galaxy halo? Does the Galaxy have a high velocity cloud phenomenon detectable in high ionization lines? What are the relationships between the high ionization and low ionization absorption? What is the relationship between absorption occurring in the outer Galaxy halo and that seen in quasar absorption line systems at low and high redshift?

Savage, Blair

1995-07-01

93

Synthesis of a carbosilane dendrimer with the functional inner shell  

Microsoft Academic Search

The carbosilane dendrimer of the fifth generation with the functional inner and nonfunctional outer shells in the molecular structure was synthesized for the first time. The efficiency of the hybrid scheme of carbosilane dendrimer synthesis based on the use of organomagnesium and organolithium reagents at different steps of molecular structure formation and hydrosilylation was shown.

E. A. Vodop\\; E. A. Tatarinova; E. A. Rebrov; A. M. Muzafarov

2004-01-01

94

Semiclassical approach to K shell ionization: hydrogenic wave functions  

Microsoft Academic Search

Proton induced K shell ionization cross sections in several elements were calculated. Semiclassical approximation with momentum space approach, hydrogenic wave functions and outer screening according to the prescription of Bethe was used. Comparison with other semiclassical and Dirac-Hartree-Slater [DHS] plane wave cross sections indicates that this type of screening — largely used in plane wave methods — implies a less

Ž. Šmit

1991-01-01

95

Microscopic models of hardness  

Microsoft Academic Search

Recent developments in the field of microscopic hardness models have been reviewed. In these models, the theoretical hardness\\u000a is described as a function of the bond density and bond strength. The bond strength may be characterized by energy gap, reference\\u000a potential, electron-holding energy or Gibbs free energy, and different expressions of bond strength may lead to different\\u000a hardness models. In

F. M. Gao; L. H. Gao

2010-01-01

96

ADAPTABLE SOFTWARE SHELLS VERSUS MICROSOFT SOFTWARE SHELLS  

Microsoft Academic Search

Development and evolution of Microsoft Office and Microsoft Windows shells is based in general on the special methodology of Software creation and implementation such as macros, subroutine, custom commands and specialized features. This methodology of Microsoft Software shells is analyzed. The universal methodology of Adaptable Software creation is proposed. Present result evaluates from (Tod-08.1)3 which is an evolution of the

Dumitru TODOROI

97

New polymer target-shell properties and characterizations  

NASA Astrophysics Data System (ADS)

A method for characterizing ICF target shells is presented, based on measurement of the gas released from a single shell into a small volume. It utilizes cryogenic permeation systems developed in connection with our work on ICF targets containing nuclear spin-polarized deuterium. Permeation rates for polystyrene and parylene-coated-polystyrene shells are measured at temperatures from 350K down to 180K. Burst or implosion pressure can be determined over a full temperature range down to 20K. Shell temperature is calculated from its gas leakage rate, calibrated by permeation measurements over the temperature range. Lag of shell temperature compared with sample-chamber temperature during warming of the latter is attributed to the weakness of the thermal link provided by both radiative heat transfer and free molecular conduction with small accommodation coefficients for helium and deuterium gas at the structure to which the shell is conductively linked, or at the surface of a conductively isolated shell. Quantification of this lag can provide a measure of atomic scale roughness of the shell outer surface. Also presented are reversible pre-rupture leakage phenomena for polystyrene and parylene-coated-polystyrene shells.

Honig, A.; Wei, X.; Fan, Q.; Alexander, N.; Palmer, N.

98

How Hard is Chocolate?  

NSDL National Science Digital Library

Hardness is probably a concept you are well familiar with. You already know that certain materials are harder than others; in fact, you prove it everyday when you chew your food and your teeth don’t break (because your teeth are harder than the foods you chew). Hardness can be defined as a material's ability to resist a change in shape. Modern hardness testers take a well-defined shape and press it into a material with a certain force, observing the indent it leaves in the material when it is removed. In this lesson, you will be performing hardness testing on different bars of chocolate.

2007-12-20

99

Ordering of hard particles between hard walls  

NASA Astrophysics Data System (ADS)

The structure of a fluid of hard Gaussian overlap particles of elongation ? = 5, confined between two hard walls, has been calculated from density-functional theory and Monte Carlo simulations. By using the exact expression for the excluded volume kernel (Velasco E and Mederos L 1998 J. Chem. Phys. 109 2361) and solving the appropriate Euler-Lagrange equation entirely numerically, we have been able to extend our theoretical predictions into the nematic phase, which had up till now remained relatively unexplored due to the high computational cost. Simulation reveals a rich adsorption behaviour with increasing bulk density, which is described semi-quantitatively by the theory without any adjustable parameters.

Chrzanowska, A.; Teixeira, P. I. C.; Ehrentraut, H.; Cleaver, D. J.

2001-05-01

100

Electrochemical characterization of a bioceramic material: The shell of the Eastern oyster Crassostrea virginica.  

PubMed

The shell of the Eastern oyster (Crassostrea virginica) is composed of multiple incongruent mineralized layers. This bioceramic composite material was investigated to determine the effects of shell thickness, orientation and layer composition on its electrochemical behavior using electrochemical impedance spectroscopy, potentiodynamic polarization and scanning electron microscopy-energy dispersive spectroscopy. SEM-EDS analysis of the oyster shell revealed that the multilayered biocomposite material is composed of calcium carbonate (CaCO(3)). EIS measurements in 3.5wt.% NaCl indicated that the impedance of the whole oyster shell in the low frequency region exhibited high impedance values which exhibited a decreasing trend with increasing immersion time. In terms of overall shell thickness, limiting currents measured by potentiodynamic techniques through the shell were observed to increase when the outer layers of the shell were sequentially removed by grinding, thus decreasing the shell thickness. These limiting current values remained relatively constant when the inner layers of the shell were removed. The impedance values of the oyster shell material as measured by EIS were shown to decrease with decreasing shell thickness. These findings suggest that the prismatic (outermost) shell layer in combination with the soluble organic matrix between all shell layers may influence the ionic conductivity through the oyster shell. PMID:21550319

Yoon, Yuhchae; Mount, Andrew S; Hansen, Karolyn M; Hansen, Douglas C

2011-04-16

101

Photoionization of two-shell endohedral atoms  

NASA Astrophysics Data System (ADS)

The photoionization of a two-shell endohedral A@CN1@CN2 is considered. Formulas are presented for cross sections and angular anisotropy parameters, both dipole and nondipole. The effect of the fullerenes shell upon photoelectron from atom A is taken into account substituting the action of the fullerene by two zero-thickness “bubble potential.” The fullerenes shells polarization is included assuming that the radius of the outer shell R2 is much bigger than the inner R1 and both much exceed the atomic radius r . This permits to express the effect via CN1,N2 polarizabilities, which are connected to their photoionization cross sections. The interaction between shells CN1 and CN2 is taken into account in the random phase approximation (RPA). The effect of photoelectron scattering by both “bubble potentials” is included in the lowest order and in the RPA frame. As concrete examples, two endohedrals Ar@C60@C240 and Xe@C60@C240 are considered. In the Ar@C60@C240 case we consider 3p and 3s , while in the case Xe@C60@C240 5p , 5s and 4d subshells are considered. A whole variety of peculiarities are found that deserve experimental verification.

Amusia, M. Ya.; Chernysheva, L. V.; Liverts, E. Z.

2009-09-01

102

Microstructural Evolution of Hypoeutectic, Near-Eutectic, and Hypereutectic High-Carbon Cr-Based Hard-Facing Alloys  

NASA Astrophysics Data System (ADS)

A series of high-carbon Cr-based hard-facing alloys were successfully fabricated on a substrate of 0.45 pct C carbon steel by gas tungsten arc welding (GTAW) process using various alloy fillers with chromium and chromium carbide, CrC (Cr:C = 4:1) powders. These claddings were designed to observe hypoeutectic, near-eutectic, and hypereutectic structures with various (Cr,Fe)23C6 and (Cr,Fe)7C3 carbides at room temperature. According to X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and optical microscopy (OM), in 3.8 pct C cladding, the microstructure consisted of the primary carbides with outer shells (Cr,Fe)23C6 surrounding (Cr,Fe)7C3 cores and [ ? + (Cr,Fe)23C6] eutectic structures. In 5.9 pct C cladding, the composite comprised primary (Cr,Fe)7C3 as the reinforcing phase and [? + (Cr,Fe)7C3] eutectic structures as matrix. Various morphologies of carbides were found in primary and eutectic (Cr,Fe)7C3 carbides, which included bladelike and rodlike (with a hexagonal cross section). The 5.9C cladding with great amounts of primary (Cr,Fe)7C3 carbides had the highest hardness (approximately HRC 63.9) of the all conditions.

Lin, Chi-Ming; Chang, Chia-Ming; Chen, Jie-Hao; Hsieh, Chih-Chun; Wu, Weite

2009-05-01

103

Session: Hard Rock Penetration  

SciTech Connect

This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of five presentations: ''Hard Rock Penetration - Summary'' by George P. Tennyson, Jr.; ''Overview - Hard Rock Penetration'' by James C. Dunn; ''An Overview of Acoustic Telemetry'' by Douglas S. Drumheller; ''Lost Circulation Technology Development Status'' by David A. Glowka; ''Downhole Memory-Logging Tools'' by Peter Lysne.

Tennyson, George P. Jr.; Dunn, James C.; Drumheller, Douglas S.; Glowka, David A.; Lysne, Peter

1992-01-01

104

The symmetries of outer space  

Microsoft Academic Search

For n?3, the natural map\\u000aOut(Fn<\\/sub>)?Aut(Kn<\\/sub>)\\u000afrom the outer automorphism group of the free group of rank\\u000an to the group of simplicial automorphisms of the spine of\\u000aouter space is an isomorphism.

Martin R. Bridson; Karen Vogtmann

2001-01-01

105

Diamonds in the outer planets  

Microsoft Academic Search

The results of space exploration over the last 2 years have provoked considerable and widespread interest, among geoscientists, in the interiors of the outer planets. Even new data on remote Uranus and Neptune are becoming available, and so it is not unusual to expect a round of new speculation on their interior compositions and properties. In a very recent article

Peter M. Bell

1981-01-01

106

OUTER LOOP LANDFILL CASE STUDY  

EPA Science Inventory

This presentation will describe the interim data reaulting from a CRADA between USEPA and Waste Management, Inc. at the outer Loop Landfill Bioreactor research project located in Louisville, KY. Recently updated data will be presented covering landfill solids, gas being collecte...

107

Turbine airfoil with a compliant outer wall  

SciTech Connect

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.

Campbell, Christian X. (Oviedo, FL); Morrison, Jay A. (Oviedo, FL)

2012-04-03

108

Claw morphology, prey size selection and foraging efficiency in generalist and specialist shell-breaking crabs  

Microsoft Academic Search

Claw morphology, and claw-closing forces of four species of intertidal crabs from San Juan Island, Washington were compared and related these findings were related to prey size selection, shell breaking times and total handling times on their snail prey, Littorina sitkana Philippi. Two functional groups of crabs emerged: generalists and specialists on hard-shelled prey. The generalist, Hemigrapsus nudus (Dana), has

Sylvia Behrens Yamada; Elizabeth G. Boulding

1998-01-01

109

Is the umbo matrix of bivalve shells ( Laternula elliptica) a climate archive?  

Microsoft Academic Search

Heavy metal accumulation into bivalve soft tissues has received increasing interest in recent years with respect to biomonitoring of environmental change including pollution. To a lesser extent, accretion of elements from the environment into bivalve hard structures (shells) has been investigated, although the importance of the shells as environmental archives has been acknowledged. Here we report element distribution within consecutive

D. Dick; E. Philipp; M. Kriews; D. Abele

2007-01-01

110

Separating in-shell pistachio nuts from kernels using impact vibration analysis  

Microsoft Academic Search

A sorting system has been developed for the separation of small in-shell pistachio nuts from kernels without shells on the\\u000a basis of vibrations generated when moving samples strike a steel plate. Impacts between the steel plate and the hard shells,\\u000a as measured using an accelerometer attached to the bottom of the plate, produce higher frequency signals than impacts between\\u000a the

Ron P. Haff; T. C. Pearson

2007-01-01

111

Effect of soft shell hip protectors on pressure distribution to the hip during sideways falls  

Microsoft Academic Search

Introduction  While hip protectors represent a promising strategy for preventing hip fractures, clinical efficacy has been limited by poor\\u000a user compliance. Soft shell protectors may be more acceptable to users than traditional hard shell designs. However, before\\u000a embarking on clinical trials to assess efficacy, laboratory experiments are required to determine how soft shell protectors\\u000a affect the force applied during impact to

A. C. Laing; S. N. Robinovitch

2008-01-01

112

THE ADSORPTION OF METHYLENE BLUE FROM AQUEOUS SOLUTION USING WASTE AQUACULTURAL SHELL POWDERS  

Microsoft Academic Search

Shellfish shell has become one of the most significant wastes in aquaculture. In this work, three ground shells derived from oyster, hard clam and short-neck clam were used as mineral adsorbents for removal of cationic dye (i.e., methylene blue) from aqueous solution at 25 °C and initial solution pH of 7.0. The shell adsorbents possessed mesoporous structure according to their

Wen-Tien Tsai; Huei-Ru Chen; Kuan-Chi Kuo; Chia-Ying Lai; Tu-Cian Su; Yuan-Ming Chang; Jwu-Maw Yang

113

Elastic shells with high-contrast material properties as acoustic metamaterial components  

NASA Astrophysics Data System (ADS)

We analyze the acoustic multiple-scattering properties of fluid-filled, elastic cylindrical shells with highly contrasting material properties, and we find for a water background that air-filled shells homogenize into high-bulk modulus, low-density effective fluids. With the exception of a few local resonances spanning very narrow band windows, we find that for common elastic materials the shells are indistinguishable from their effective fluid counterparts for wavelengths larger than the shell's outer diameter. Furthermore, we find that when the elastic shell is composed of a material with impedance larger than water, there will be a specific shell thickness for which the effective fluid properties become impedance-matched. Finally, we demonstrate that the shells can be used as constituent components in regular lattices to create homogenized acoustic metamaterial devices.

Martin, Theodore P.; Layman, Christopher N.; Moore, Kimberly M.; Orris, Gregory J.

2012-04-01

114

Fluctuating shells under pressure  

PubMed Central

Thermal fluctuations strongly modify the large length-scale elastic behavior of cross-linked membranes, giving rise to scale-dependent elastic moduli. Whereas thermal effects in flat membranes are well understood, many natural and artificial microstructures are modeled as thin elastic shells. Shells are distinguished from flat membranes by their nonzero curvature, which provides a size-dependent coupling between the in-plane stretching modes and the out-of-plane undulations. In addition, a shell can support a pressure difference between its interior and its exterior. Little is known about the effect of thermal fluctuations on the elastic properties of shells. Here, we study the statistical mechanics of shape fluctuations in a pressurized spherical shell, using perturbation theory and Monte Carlo computer simulations, explicitly including the effects of curvature and an inward pressure. We predict novel properties of fluctuating thin shells under point indentations and pressure-induced deformations. The contribution due to thermal fluctuations increases with increasing ratio of shell radius to thickness and dominates the response when the product of this ratio and the thermal energy becomes large compared with the bending rigidity of the shell. Thermal effects are enhanced when a large uniform inward pressure acts on the shell and diverge as this pressure approaches the classical buckling transition of the shell. Our results are relevant for the elasticity and osmotic collapse of microcapsules.

Paulose, Jayson; Vliegenthart, Gerard A.; Gompper, Gerhard; Nelson, David R.

2012-01-01

115

Non-uniform thickness in Europa's icy shell: implications for astrobiology mission design  

NASA Astrophysics Data System (ADS)

The exploration of Europa's subsurface ocean is hardly constrained by the presence of an outer ice shell of unknown thickness: a somewhat thin crust would allow easier access to the ocean below. Current estimates for the thickness of Europa's icy surface range from a few km [1] to a few tens of km [2], the shell overlying a liquid water ocean up to 150 km thick [3,4,5]. The surface is believed to be young (mean age of 30-80 Myr [6]) and geologically active [7,8,9], as it is sparsely cratered. Here we report geological evidence indicating that the thickness of Europa's ice crust is actually a complex combination of thicker and thinner areas, highlighting the implications of such structure in the future exploration of the inner ocean. Detailed geologic mapping of impact craters, palimpsests and chaotic terrains distribution on Europa's surface, offers an initial approach to a comprehensive description of the thickness variation in the ice shell. Our analysis is based in: (1) Crater distribution, morphology, diameter and depth. Seminal work by Schenk [2] of transitions in crater shape/diameter suggested enhanced structural collapse of craters with diameter >27-33 km, that will consequently form multiring basins, due to weaker ice or a global ocean at depths >19-25 km. This being true, strictly can only be interpreted regionally: multiring basins indicate regions where the ice shell is thick; in those regions where the icy surface is thin, a bolide impact will breach the ice and leave neither crater nor multiring basin behind, but probably Ganymede's type palimpsests. (2) Palimpsest-type features distribution, indicating regions where the ice shell is too thin to support crater formation after big bolide impacts. In Ganymede, palimpsests are circular, low albedo and relief features formerly formed by impacts [10,11]. (3) Chaotic terrain distribution, considering features tens to hundreds of km across, that may be the evidence for very thin ice areas (from ˜ 2 km to zero shell thickness [12]) with liquid water at shallow depths [5], allowing for bolide penetration, diapirism and the extrusion of water to the surface. The heterogeneity in shell's thickness may be originated in spatial variations in tidal heating [13] and/or warm water upwellings from the silicate interior capable of melt-through the ice from below [12,14]. This thickness heterogeneity can be embedded in a general equatorward thickening trending, due to tidal dissipation and surface temperature variations [15]. A major constraint must be addressed at this point: the dynamism of ductile ice near the base of the shell may drive to decay in lateral thickness contrasts. But this effect has been examined both assuming ice as a Newtonian [16,17,18] and a non-Newtonian material [19], broadly reaching to similar conclusions: global shell thickness variations may survive for up to 100 Myr. In addition, lateral pressure gradients may not decay if they comprise only shallow depths [19]. Therefore, our results point to a dynamic non-uniform Europa's icy shell, displaying some regional and temporal heterogeneity in thickness. As thin/thick ice distribution is as time dependent as the surface ice features are (both are reshaped in periods ˜ 100 Myr), the analysis performed here offers an estimation of the current thickness distribution in the ice shell, estimation that cannot be extrapolated to ancient (e.g., >100 Myr) times. The astrobiological potential the shell and ocean below possess is highlighted by these results: a somewhere thin outer crust allows the possibility for some exogenous materials delivered by asteroids and comets to reach the inner liquid water ocean by breaching the brittle lithosphere [20], and so join to those generated in the interior of Europa via volcanic and hydrothermal activity [21]. In addition, pressure gradients driving the ductile ice at the base of the shell to flow laterally may help to redistribute such materials among the inner ice shell and/or ocean through time. Our results have a direct deal with the investigation of Eur

Fairén, A.; Amils, R.

116

Hard Probes 2006: Theoretical Summary  

NASA Astrophysics Data System (ADS)

What makes a hard process a hard probe of hot and dense nuclear matter? In the context of this question, I review recent results shown by the theory speakers at the 2nd Hard Probes Conference in Asilomar.

Wiedemann, Urs Achim

2007-02-01

117

Physics of the outer heliosphere  

SciTech Connect

Major advances in the physics of the outer heliosphere are reviewed for the 1987-1990 time frame. Emphasis is placed on five broad topics: the detailed structure of the solar wind at large heliocentric distances, the global structure of the interplanetary field, latidudinal variations and meridional flows, radial and temporal variations, and the interaction of the solar wind with the local interstellar medium. 122 refs.

Gazis, P.R. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

118

Radiation from hard objects  

SciTech Connect

The inference of the diameter of hard objects is insensitive to radiation efficiency. Deductions of radiation efficiency from observations are very sensitive - possibly overly so. Inferences of the initial velocity and trajectory vary similarly, and hence are comparably sensitive.

Canavan, G.H.

1997-02-01

119

L shell distribution of energetic electrons at Saturn  

NASA Astrophysics Data System (ADS)

Energetic electron fluxes (110-485 keV) observed by the MIMI/LEMMS instrument on the Cassini mission to Saturn were averaged into azimuthal bins and L shell bins for the period from day 150 2004 to day 366 2008. In local time, the electrons fluxes maximize on the night side between the Mimas and Rhea L shells and have a minimum near noon. This local time behavior may be a result of nightside injection combined with subcorotational drift in a nondipolar field. In SLS longitude, the electrons are smoothly distributed, showing no signs of spiral patterns on this multiyear timescale. The lower energy electrons (110-365 keV) form an inner belt near the Mimas L shell and an outer belt between the Dione and Rhea L shells.

Carbary, J. F.; Mitchell, D. G.; Krupp, N.; Krimigis, S. M.

2009-09-01

120

Lines of minima in Outer space  

Microsoft Academic Search

We define lines of minima in the thick part of Outer space for the free group Fn with n>2 generators. We show that these lines of minima are contracting for the Lipschitz metric. Every fully irreducible outer automorphism of Fn defines such a line a minima. Now let G be a subgroup of the outer automorphism group of Fn which

Ursula Hamenstaedt

2009-01-01

121

Studies on molluscan shells: contributions from microscopic and analytical methods.  

PubMed

Molluscan shells have always attracted the interest of researchers, from biologists to physicists, from paleontologists to materials scientists. Much information is available at present, on the elaborate architecture of the shell, regarding the various Mollusc classes. The crystallographic characterization of the different shell layers, as well as their physical and chemical properties have been the subject of several investigations. In addition, many researches have addressed the characterization of the biological component of the shell and the role it plays in the hard exoskeleton assembly, that is, the biomineralization process. All these topics have seen great advances in the last two or three decades, expanding our knowledge on the shell properties, in terms of structure, functions and composition. This involved the use of a range of specialized and modern techniques, integrating microscopic methods with biochemistry, molecular biology procedures and spectroscopy. However, the factors governing synthesis of a specific crystalline carbonate phase in any particular layer of the shell and the interplay between organic and inorganic components during the biomineral assembly are still not widely known. This present survey deals with microstructural aspects of molluscan shells, as disclosed through use of scanning electron microscopy and related analytical methods (microanalysis, X-ray diffraction, electron diffraction and infrared spectroscopy). These already published data provide relevant information on shells and also contribute for better understanding the biomineralization process. PMID:19524444

de Paula, Silvia Maria; Silveira, Marina

2009-05-18

122

Synthesis and enhanced gas sensing properties of crystalline CeO 2\\/TiO 2 core\\/shell nanorods  

Microsoft Academic Search

Crystalline CeO2\\/TiO2 core\\/shell nanorods were fabricated by a hydrothermal method and a subsequent annealing process under the hydrogen and air atmosphere. The thickness of the outer shell composed of crystal TiO2 nanoparticles can be tuned in the range of 5–11nm. The crystal core\\/shell nanorods exhibited enhanced gas-sensing properties to ethanol vapor in terms of sensor response and selectivity. The calculated

Yu-Jin Chen; Gang Xiao; Tie-Shi Wang; Fan Zhang; Yang Ma; Peng Gao; Chun-Ling Zhu; Endi Zhang; Zhi Xu; Qiu-hong Li

2011-01-01

123

Polydisperse hard spheres at a hard wall  

NASA Astrophysics Data System (ADS)

The structural properties of polydisperse hard spheres in the presence of a hard wall are investigated via Monte Carlo simulation and density functional theory (DFT). Attention is focused on the local density distribution ?(?,z), measuring the number density of particles of diameter ? at a distance z from the wall. Estimates of ?(?,z) are obtained for bulk volume fractions ?b=0.2 and ?b=0.4, and for two choices of the bulk parent distribution: a top-hat form, which we study for degrees of polydispersity ?=11.5% and ?=40.4%, and a truncated Schulz form having ?=40.7%. Excellent overall agreement is found between the DFT and simulation results, particularly at ?b=0.2. A detailed analysis of ?(?,z) confirms the presence of oscillatory size segregation effects, as observed in a previous DFT study [I. Pagonabarraga, M. E. Cates, and G. J. Ackland, Phys. Rev. Lett. 84, 911 (2000)]. For large ?, the character of these oscillation is observed to depend strongly on the shape of the parent distribution. In the vicinity of the wall, attractive ?-dependent depletion interactions are found to greatly enhance the density of the largest particles. The local degree of polydispersity ?(z) is suppressed in this region, while further from the wall it exhibits oscillations.

Buzzacchi, Matteo; Pagonabarraga, Ignacio; Wilding, Nigel B.

2004-12-01

124

Wall-Thickness Dependence of Cooling-Induced Deformation of Polystyrene Spherical Shells  

SciTech Connect

Experiments on the wall-thickness dependence of the cooling-induced deformation (CID) of polystyrene (PS) spherical shells were carried out. For the experiments, the PS shells were fabricated by the density-matched emulsion method using the hand-shaken microencapsulation technique. The number-averaged and weight-averaged molecular weights of the PS were M{sub n} 1.1 x 10{sup 5} and M{sub w} = 4.0 x 10{sup 5}, respectively. The diameter of the PS shells was {approx}400-550 {mu}m. To investigate the wall-thickness dependence of the CID, the wall thickness of the PS shells was varied between 5 and 60 {mu}m. In the experiments, the PS shells were cooled by using liquid nitrogen, and their images were captured at 0 and -190 deg. C. For the investigation of the CID, two shapes of each shell that were measured at 0 and -190 deg. C were compared. The thinner PS shells showed larger CID. The maximum deformation was almost 1% of the outer radius when the shell aspect ratio (outer radius)/(wall thickness) was higher than 20. The repeatability of the CID was studied, and the results implied that residual stress in the PS shells had an influence on the CID.

Endo, T.; Kobayashi, N.; Goto, K.; Yasuda, M.; Fujima, Y. [Nagoya University (Japan)

2003-05-15

125

Magnetospheres of the outer planets  

SciTech Connect

The magnetospheres of the outer planets have been shown by Voyager explorations to strongly interact with the surfaces and atmospheres of their planetary satellites and rings. In the cases of Jupiter, Saturn and Uranus, the processes of charged particle sputtering, neutral gas cloud formation, and rapid plasma injection from the ionization of the neutral clouds, have important implications both for the magnetospheres as a whole and for the surfaces and atmospheres of their satellites. The general methodology employed in these researches has involved comparisons of the planetary magnetospheres in order to identify common physical processes. 16 references.

Cheng, A.F.

1986-12-01

126

The CDF Central Outer Tracker  

SciTech Connect

We describe the CDF Central Outer Tracker (COT), an open-cell drift chamber currently being constructed for the CDF detector to run at the upgraded Fermilab Tevatron collider. This detector will provide central tracking with excellent momentum resolution in the high- density environment of a hadron collider. It will be able to resolve 132 ns beam crossings and provide tracking trigger information to the Level 1 trigger. The design is based upon the existing and successful CDF Central Tracking Chamber. The preliminary mechanical and electrical designs are presented. 5 refs., 5 figs., 1 tab.

Pitts, K.T.; CDF Collaboration

1997-01-01

127

SHELL EGG QUALITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

The goal of all producers is to produce a better product. In the shell egg industry, this translates to producing a higher quality egg. Egg quality can be defined in many ways. The American consumer demands a clean and sound egg that looks appealing when cracked into a skillet. The shell egg pr...

128

Multifunctional core–shell nanoparticles: superparamagnetic, mesoporous, and thermosensitive  

Microsoft Academic Search

Multifunctional core–shell composite nanoparticles (NPs) have been developed by the combination of three functionalities into\\u000a one entity, which is composed of a single Fe3O4 NP as the magnetic core, mesoporous silica (mSiO2) with cavities as the sandwiched layer, and thermosensitive poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAAm-co-AAm)) copolymer as the outer shell. The mSiO2-coated Fe3O4 NPs (Fe3O4@mSiO2) are monodisperse and the particle sizes were varied

Fei YeJian; Jian Qin; Muhammet S. Toprak; Mamoun Muhammed

129

Hard superconducting nitrides  

PubMed Central

Detailed study of the equation of state, elasticity, and hardness of selected superconducting transition-metal nitrides reveals interesting correlations among their physical properties. Both the bulk modulus and Vickers hardness are found to decrease with increasing zero-pressure volume in NbN, HfN, and ZrN. The computed elastic constants from first principles satisfy c11 > c12 > c44 for NbN, but c11 > c44 > c12 for HfN and ZrN, which are in good agreement with the neutron scattering data. The cubic ?-NbN superconducting phase possesses a bulk modulus of 348 GPa, comparable to that of cubic boron nitride, and a Vickers hardness of 20 GPa, which is close to sapphire. Theoretical calculations for NbN show that all elastic moduli increase monotonically with increasing pressure. These results suggest technological applications of such materials in extreme environments.

Chen, Xiao-Jia; Struzhkin, Viktor V.; Wu, Zhigang; Somayazulu, Maddury; Qian, Jiang; Kung, Simon; Christensen, Axel N?rlund; Zhao, Yusheng; Cohen, Ronald E.; Mao, Ho-kwang; Hemley, Russell J.

2005-01-01

130

Hard superconducting nitrides.  

PubMed

Detailed study of the equation of state, elasticity, and hardness of selected superconducting transition-metal nitrides reveals interesting correlations among their physical properties. Both the bulk modulus and Vickers hardness are found to decrease with increasing zero-pressure volume in NbN, HfN, and ZrN. The computed elastic constants from first principles satisfy c11 > c12 > c44 for NbN, but c11 > c44 > c12 for HfN and ZrN, which are in good agreement with the neutron scattering data. The cubic delta-NbN superconducting phase possesses a bulk modulus of 348 GPa, comparable to that of cubic boron nitride, and a Vickers hardness of 20 GPa, which is close to sapphire. Theoretical calculations for NbN show that all elastic moduli increase monotonically with increasing pressure. These results suggest technological applications of such materials in extreme environments. PMID:15728352

Chen, Xiao-Jia; Struzhkin, Viktor V; Wu, Zhigang; Somayazulu, Maddury; Qian, Jiang; Kung, Simon; Christensen, Axel Nørlund; Zhao, Yusheng; Cohen, Ronald E; Mao, Ho-kwang; Hemley, Russell J

2005-02-22

131

A Mathematical Model of the Proton Balance in the Outer Mantle Epithelium of Anodonta cygnea L  

Microsoft Academic Search

In the freshwater mollusc Anodonta cygnea and other unionids, the mantle plays an important role in the regulation of the movements of ions between the shell and the\\u000a extrapaleal fluid. In this report, a mathematical model that attempts to describe the cell metabolic mechanisms underlying\\u000a the operation of the outer mantle epithelium as a source of protons is presented. We

P. F. Oliveira; A. Rebelo da Costa; H. G. Ferreira

2008-01-01

132

Diffractive hard scattering  

SciTech Connect

I discuss events in high energy hadron collisions that contain a hard scattering, in the sense that very heavy quarks or high P/sub T/ jets are produced, yet are diffractive, in the sense that one of the incident hadrons is scattered with only a small energy loss. 8 refs.

Berger, E.L.; Collins, J.C.; Soper, D.E.; Sterman, G.

1986-03-01

133

CSI: Hard Drive  

ERIC Educational Resources Information Center

|Acting on information from students who reported seeing a classmate looking at inappropriate material on a school computer, school officials used forensics software to plunge the depths of the PC's hard drive, searching for evidence of improper activity. Images were found in a deleted Internet Explorer cache as well as deleted file space.…

Sturgeon, Julie

2008-01-01

134

Budgeting in Hard Times.  

ERIC Educational Resources Information Center

|Interviews with school board members and administrators produced a list of suggestions for balancing a budget in hard times. Among these are changing calendars and schedules to reduce heating and cooling costs; sharing personnel; rescheduling some extracurricular activities; and forming cooperative agreements with other districts. (MLF)|

Parrino, Frank M.

2003-01-01

135

Work Hard. Be Nice  

ERIC Educational Resources Information Center

|In 1994, fresh from a two-year stint with Teach for America, Mike Feinberg and Dave Levin inaugurated the Knowledge Is Power Program (KIPP) in Houston with an enrollment of 49 5th graders. By this Fall, 75 KIPP schools will be up and running, setting children from poor and minority families on a path to college through a combination of hard work,…

Mathews, Jay

2009-01-01

136

Running in Hard Times  

ERIC Educational Resources Information Center

|Roberta Stevens and Kent Oliver are campaigning hard for the presidency of the American Library Association (ALA). Stevens is outreach projects and partnerships officer at the Library of Congress. Oliver is executive director of the Stark County District Library in Canton, Ohio. They have debated, discussed, and posted web sites, Facebook pages,…

Berry, John N., III

2009-01-01

137

Records of River Variation in the Shells of Freshwater Bivalves  

NASA Astrophysics Data System (ADS)

The skeletons of hard-shelled invertebrates such as corals and bivalves are commonly used in marine settings as archives of environmental information. They are less commonly used in freshwater settings where variability in water chemistry makes it more difficult to calibrate chemical proxies such as the Sr:Ca in a shell. Our objective is to evaluate whether trace element concentrations in freshwater bivalve shells contain information on environmental conditions. Multiple elements (Ba, Cu, Mn and Sr) were analyzed within the shells of modern bivalves from four streams on DOE's Savannah River Site in S.C. Laser Ablation ICP-MS was used to measure elemental concentrations across five aragonitic shells from each site. These elements were chosen because they are present in detectable concentrations (ppm) in the shell and they have been suggested as useful proxies for temperature, rainfall, productivity and pollution. Results were compared to historical monthly site records of water chemistry and chemical analyses of water samples collected from the streams where the clams were found. The average shell concentrations of Sr and Mn were significantly different between sites and increased proportionally to water concentration. This was not observed for Ba and Cu. For example, the Ba concentrations of shells collected at a site downstream of a lake were higher than those for shells from stream sites with significantly higher dissolved Ba concentrations. Copper was only detected at dark growth lines with the number of lines and shell material between them varying between shells within the same stream. Intrashell profiles of Ba, Sr and Mn concentrations exhibited cyclical variation. The magnitude of cyclical variation for Mn and Sr within a shell corresponds with the annual variation in monthly water sample concentrations. Again, this pattern was not observed for Ba, especially in shells from the site downstream of a lake. This supports suggestions that particulate organic matter, to which Ba preferentially partitions, plays a role in bivalve Ba uptake. Finally, variations in Ba, Cu, Mn and Sr profiles across shells are not in unison. The individual elemental responses to biological and physicochemical effects suggest that the elemental records in freshwater bivalve shells can be interpreted as environmental proxies.

Carroll, M.; Romanek, C.

2005-12-01

138

Chandra Peers Into Outer Space  

NSDL National Science Digital Library

NASA's newest space telescope, the Chandra X-ray Observatory, was launched into orbit only two months ago. Named for the late Indian-American Nobel laureate, Subrahmanyan Chandrasekhar, the Chandra Observatory is already providing scientists with the first "X-ray images and spectra of violent, high-temperature events and objects." In addition to their sheer mystique, these color images increase scientists's understanding of the structure and evolution of the universe. Managed by NASA's Marshall Space Flight Center in Huntsville, Alabama, the Chandra X-Ray Observatory also serves as a unique tool for studying detailed physics "in a unique laboratory -- the universe itself." This week's In The News highlights the Chandra X-Ray Observatory; the nine sites listed offer background information, commentary, and recent images from outer space.

Payne, Laura X.

139

Isomorphic shell model for closed-shell nuclei  

Microsoft Academic Search

The classical part of the isomorphic model for closed-shell nuclei is presented based on two physical assumptions, namely (a) the nucleons of a closed shell nucleus, considered at their most probable positions, are in an instantaneous dynamic equilibrium on spherical shells, and (b) the dimensions of the shells are determined by their close packing given that a neutron and a

G. S. Anagnostatos

1985-01-01

140

Isomorphic Shell Model for Closed-Shell Nuclei  

Microsoft Academic Search

The classical part of the isomorphic model for closed-shell nuclei is presented based on two physical assumptions, namely (a) the nucleons of a closed shell nucleus, considered at their most probable positions, are in an instantaneous dynamic equilibrium on spherical shells, and (b) the dimensions of the shells are determined by their close packing given that a neutron and a

G. S. Anagnostatos

1985-01-01

141

Stable carbon isotopes in freshwater mussel shells: Environmental record or marker for metabolic activity?  

NASA Astrophysics Data System (ADS)

Mussel shells have been used in a number of paleoecological and environmental studies. The interpretation of stable carbon isotopic composition of shell material is still controversial. The carbon for shell carbonate precipitation can either be derived from ambient dissolved inorganic carbon (DIC), with shells recording environmental signals, or from metabolic CO2, with the potential to disguise environmental signals. To gain insight into this question, we investigated four nearly 100-yr long-term records of aragonite shells from an extant freshwater bivalve species, the endangered freshwater pearl mussel (Margaritifera margaritifera L.). Single growth increments of the outer prismatic and the inner nacreous zones were successfully and easily separated with a simple heat treatment for chronological analyses of ?13C in single layers of each zone. Autocorrelation and semivariance statistical methods reveal that mussels show distinct individual signal patterns, which extend up to 25 yr. Signal patterns are reliably reproduced with replicate samples from defined layers within one shell and show similar patterns with a slight offset for inner nacreous and outer prismatic layers for individual animals. Mussels exposed to the same environmental conditions exhibit distinct and contradictory signature patterns, which do not match between individuals. This observation can only be explained by strong metabolic influences on shell precipitation. Environmental changes in pH, temperature, electric conductivity and atmospheric carbon signature had no or little (<5%) influence, whereas body tissue protein and body tissue ?13C signatures negatively correlated with the youngest produced shell ?13C signatures, indicating that respiration causes a preferential loss of light isotopes from body mass and an inverse enrichment in shell aragonite. Hence, the shells of the freshwater pearl mussel yield a long-term record of metabolic activity, whereas the use of ?13C in these shells as recorder for environmental signals is questionable. This may also be true for shells from other species, for which metabolic carbon incorporation has been acknowledged.

Geist, Juergen; Auerswald, Karl; Boom, Arnoud

2005-07-01

142

Resolving the outer density profile of dark matter halo in Andromeda galaxy  

NASA Astrophysics Data System (ADS)

Large-scale faint structure detected by the recent observations in the halo of the Andromeda galaxy (M31) provides an attractive window to explore the structure of outer cold dark matter (CDM) halo in M31. Using an N-body simulation of the interaction between an accreting satellite galaxy and M31, we investigate the mass-density profile of the CDM halo. We find the sufficient condition of the outer density profile of CDM halo in M31 to reproduce the Andromeda giant stream and the shells at the east and west sides of M31. The result indicates that the density profile of the outer dark matter halo of M31 is a steeper than the prediction of the theory of the structure formation based on the CDM model.

Kirihara, Takanobu; Miki, Yohei; Mori, Masao

2013-08-01

143

Characteristics of acoustic scattering from a double-layered micro shell for encapsulated drug delivery  

Microsoft Academic Search

This work examines the characteristic differences in acoustic scattering between air-filled double-layered encapsulating (DLE) shells and air-filled single-layered encapsulating (SLE) shells. The analysis shows that the presence of an outer layer softer than the inner layer results in a shift of the first monopole of the reflectivity-frequency response to a higher frequency and a reduction in the monopole peak; and

Yuantai Hu; Shengping Qin; Qing Jiang

2004-01-01

144

Simplified nonlinear outer hair cell models  

NASA Astrophysics Data System (ADS)

We present a consistent second-order expansion of nonlinear constitutive theories for outer hair cells. For a particular theory, we will test the validity of such a model for small variations in voltage and strain about the resting state of outer hair cells. An analysis of the various terms in the simplified nonlinear model and their relevance to outer hair cell mechanics are presented. Results show that the second-order expansion is adequate for modeling outer hair cell mechanics in a global model of the cochlea. Model predictions agree with the notion that voltage nonlinearities are the dominant ones at low sound levels in vivo. .

Deo, Niranjan; Grosh, Karl

2005-04-01

145

Comparison of Ultrasonic-Hardness-Tester Hardness and Micro-Vickers Hardness  

NASA Astrophysics Data System (ADS)

Examination methods of industrial hardnesses such as Vickers hardness and Rockwell hardness are used for the characteristic measurement of materials. These methods assume that the length of the plastic deformation is a reliable index of hardness. Since the indenters used in these methods produce deformation imprints and the methods themselves are difficult to perform, they cannot be used for the ready measurement of hardness. Recently, a nondestructive ultrasonic hardness tester that is capable of measuring the hardness of materials has been developed by the authors. This tester can measure small areas rapidly and accurately. Another advantage of this tester is that it can measure a wide range of hardness. Therefore, we consider that it is highly advantageous to replace conventional hardness testers with ultrasonic hardness testers. In this study, ultrasonic hardness was compared with micro-Vickers hardness. As a result, it was clarified that micro-Vickers hardness was in proportion to the 4.25th power of the index of ultrasonic hardness.

Aoyagi, Ryoji; Umezu, Kaoru

2007-07-01

146

Shells and Patterns  

ERIC Educational Resources Information Center

|"Shells and Patterns" was a project the author felt would easily put smiles on the faces of her fifth-graders, and teach them about unity and the use of watercolor pencils as well. It was thrilling to see the excitement in her students as they made their line drawings of shells come to life. For the most part, they quickly got the hang of…

Sutley, Jane

2009-01-01

147

A rigid and weathered ice shell on Titan  

NASA Astrophysics Data System (ADS)

Several lines of evidence suggest that Saturn's largest moon, Titan, has a global subsurface ocean beneath an outer ice shell 50 to 200kilometres thick. If convection is occurring, the rigid portion of the shell is expected to be thin; similarly, a weak, isostatically compensated shell has been proposed to explain the observed topography. Here we report a strong inverse correlation between gravity and topography at long wavelengths that are not dominated by tides and rotation. We argue that negative gravity anomalies (mass deficits) produced by crustal thickening at the base of the ice shell overwhelm positive gravity anomalies (mass excesses) produced by the small surface topography, giving rise to this inverse correlation. We show that this situation requires a substantially rigid ice shell with an elastic thickness exceeding 40 kilometres, and hundreds of metres of surface erosion and deposition, consistent with recent estimates from local features. Our results are therefore not compatible with a geologically active, low-rigidity ice shell. After extrapolating to wavelengths that are controlled by tides and rotation, we suggest that Titan's moment of inertia may be even higher (that is, Titan may be even less centrally condensed) than is currently thought.

Hemingway, D.; Nimmo, F.; Zebker, H.; Iess, L.

2013-08-01

148

Morphogenesis of active shells.  

PubMed

We consider the active shell as a single-cell or epithelial sheet surface that, sharing basic properties of stretched elastic shells, is capable of active planar movement owing to recruiting of the new surface elements. As model examples of their morphogenesis, we consider the growth and differentiation of single-cell hairs (trichomes) in plants of the genus Draba, and the epiboly and formation of the dorsoventral polarity in loach. The essential feature of the active shell behavior at both cellular and supracellular levels is regular deviating from the spatially homogeneous form, which is a primary cause of originating of the active mechanical stresses inside the shell in addition to its passive stretching by the intrinsic forces. Analyzing the quantitative morphological data, we derive the equations in which the temporal self-oscillations and spatial differentiation are distinguishable only at the parametric level depending on the proportion of active to passive stresses. In contrast to the ordinary activator-inhibitor systems, the self-oscillation dynamics is principally non-local and, consequently, one-parametric, the shell surface curvature being an analog of the inhibitor, while its spatial variance being an analog of the activator of shaping. Analyzing variability and evolution of the hair cell branching, we argue that the linear ontogeny (succession of the developmental stages) is a secondary evolutionary phenomenon originating from cyclic self-organizing algorithms of the active shell shaping. PMID:22613513

Cherdantsev, Vladimir G; Grigorieva, Olga V

2012-05-18

149

Hard surface detergency  

Microsoft Academic Search

In a study of hard surface detergency using glyceryl trioleate, oleic acid, and octanoic acid soils with three types of anionic\\u000a and three types of nonionic syndets, only potassium laurate showed maximum detergency at the CMC (critical micelle concentration),\\u000a with the potassium laurateoctanoic acid system being an exception. In general glyceryl trioleate and oleic soil removal (180°F.)\\u000a at the CMC

A. M. Mankowich

1961-01-01

150

Eat Smart. Play Hard.  

NSDL National Science Digital Library

The Food and Nutrition Service of the US Department of Agriculture offers online educational material as part of "Eat Smart. Play Hard." -- a public information campaign designed to promote healthy living in American children. While the site and its materials are geared for use by state and local program coordinators, anyone is welcome to download the available information and activity sheets. Click on Cool Stuff for Kids for nutrition-related puzzles and games. Parents Place offers informational brochures and an educational bookmark.

151

Outer zone electron precipitation produced by a VLF transmitter  

SciTech Connect

By means of high-resolution pitch angle measurements made by a magnetic-focusing electron spectrometer on the S3-3 satellite while in the drift loss cone region of the magnetosphere, characteristics of fluxes of 108- to 654-keV electron precipitated in the inner zone, in the slot region, and in the outer zone of the magnetosphere are all shown to be consistent with the precipitation's having been produced by the same ground-based VLF transmitter, UMS. Pitch angle measurements are used to locate the longitude of precipitation. The temporal pattern of transmitter operation obtained from synoptic data from a ground-based VLF receiver is used along with drift rate calculations to predict the electron energies as a function of L shell which should be observable by the S3-3 instrument. The predicted energy response is then compared with the in situ observations, getting complete agreement. Finally, wave-particle resonance calculations are made for each of the three regions. The study indicates that ground-based VLF transmitters, which have previously been shown to produce precipitation in the inner zone and slot regions, are almost certainly instrumental in precipitating electrons in the outer zone also. copyright American Geophysical Union 1988

Vampola, A.L.; Adams, C.D.

1988-03-01

152

Fabrication of Hard Glass Plates.  

National Technical Information Service (NTIS)

This report describes the fabrication of hard glass for use in ballistic application. The work consisted of establishing optimum composition and process conditions for several different glasses. Properties such as Knoop hardness, density, flexural strengt...

A. Z. Hed M. A. Ali

1974-01-01

153

Radial variations in modulus and hardness in SCS-6 silicon carbide fibers  

SciTech Connect

The mechanical properties of SCS-6 SiC fibers were measured as a function of fiber radius using nanoindentation techniques. Hardness and Young`s modulus were characterized for the material in all of the major regions of these fibers: the carbon core, the graphitic core coating, the inner SiC sheath, and the outer SiC sheath. The carbon core of the fibers was determined to be uniform in properties but extremely compliant. Young`s modulus of 28 GPa and a hardness of 4.2 GPa were measured. The graphitic core coating was found to exhibit considerable anelasticity and to have both a low modulus (21 GPa) and a low hardness (1.7 GPa). The inner sheath of the fiber, which contained a varying chemistry, showed a sharp increase in stiffness and hardness from the inner core. Modulus and hardness increased by an order of magnitude over just 1 or 2 {micro}m when transversing radially away from the core into the SiC. This change in properties was pronounced and clearly defined. The outer sheath, which contained a uniform chemistry and microstructure, was consistently stiff and hard when transversing radially. The average modulus and hardness for the full fiber was 333 GPa. The values reported for Young`s modulus and hardness clearly showed that the mechanical properties of SCS SiC fibers exhibit dramatic changes across their diameters.

Mann, A.B.; Weihs, T.P. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Materials Science and Engineering; Balooch, M.; Kinney, J.H. [Lawrence Livermore National Lab., CA (United States). Dept. of Chemistry and Materials Science

1999-01-01

154

SUPER HARD SURFACED POLYMERS  

SciTech Connect

High energy ion beam surface treatments were applied to a selected group of polymers. Of the six materials in the present study, four were thermoplastics (polycarbonate, polyethylene, polyethylene terephthalate, and polystyrene) and two were thermosets (epoxy and polyimide). The particular epoxy evaluated in this work is one of the resins used in formulating fiber reinforced composites for military helicopter blades. Measures of mechanical properties of the near surface regions were obtained by nanoindentation hardness and pin on disk wear. Attempts were also made to measure erosion resistance by particle impact. All materials were hardness tested. Pristine materials were very soft, having values in the range of approximately 0.1 to 0.5 GPa. Ion beam treatment increased hardness by up to 50 times compared to untreated materials. For reference, all materials were hardened to values higher than those typical of stainless steels. Wear tests were carried out on three of the materials, PET, PI and epoxy. On the ion beam treated epoxy no wear could be detected, whereas the untreated material showed significant wear.

Mansur, Louis K [ORNL; Bhattacharya, R [UES, Incorporated, Dayton, OH; Blau, Peter Julian [ORNL; Clemons, Art [ORNL; Eberle, Cliff [ORNL; Evans, H B [UES, Incorporated, Dayton, OH; Janke, Christopher James [ORNL; Jolly, Brian C [ORNL; Lee, E H [Consultant, Milpitas, CA; Leonard, Keith J [ORNL; Trejo, Rosa M [ORNL; Rivard, John D [ORNL

2010-01-01

155

Hard-pan soils - Management  

Technology Transfer Automated Retrieval System (TEKTRAN)

Hard pans, hard layers, or compacted horizons, either surface or subsurface, are universal problems that limit crop production. Hard layers can be caused by traffic or soil genetic properties that result in horizons with high density or cemented soil particles; these horizons have elevated penetrati...

156

Outer space travelling board game  

US Patent & Trademark Office Database

An entertaining board game for pre-school-age children and children in the primary grades. The board game comprises a path of globe shaped spaces having a starting point and an ending point. Each globe shaped space is distinguished by a color or a picture depicted thereon. Corresponding to the globe shaped spaces are playing cards each either having a colored globe, a picture, or a colored globe and picture thereon. Players move by selecting by chance a card, matching the color of the globe or picture on the card with a corresponding globe shaped space and moving to the appropriate globe shaped space according to the rules. Thus, the game is designed to introduce outer space through color matching and picture matching. Rhymes and mythology as stated on certain cards is also introduced giving the child a unique experience or adventure on the pictured places as pictured on the playing cards, but it is not necessary to read in order to play the game.

Hofmann; Elsa O. (Montclair, NJ)

1989-02-14

157

Methylmercury targets photoreceptor outer segments.  

PubMed

Human populations experience widespread low level exposure to organometallic methylmercury compounds through consumption of fish and other seafood. At higher levels, methylmercury compounds specifically target nervous systems, and among the many effects of their exposure are visual disturbances, including blindness, which previously were thought to be due to methylmercury-induced damage to the visual cortex. Here, we employ high-resolution X-ray fluorescence imaging using beam sizes of 500 × 500 and 250 × 250 nm(2) to investigate the localization of mercury at unprecedented resolution in sections of zebrafish larvae ( Danio rerio ), a model developing vertebrate. We demonstrate that methylmercury specifically targets the outer segments of photoreceptor cells in both the retina and pineal gland. Methylmercury distribution in both tissues was correlated with that of sulfur, which, together with methylmercury's affinity for thiolate donors, suggests involvement of protein cysteine residues in methylmercury binding. In contrast, in the lens, the mercury distribution was different from that of sulfur, with methylmercury specifically accumulating in the secondary fiber cells immediately underlying the lens epithelial cells rather than in the lens epithelial cells themselves. Since methylmercury targets two main eye tissues (lens and photoreceptors) that are directly involved in visual perception, it now seems likely that the visual disruption associated with methylmercury exposure in higher animals including humans may arise from direct damage to photoreceptors, in addition to injury of the visual cortex. PMID:23957296

Korbas, Malgorzata; Lai, Barry; Vogt, Stefan; Gleber, Sophie-Charlotte; Karunakaran, Chithra; Pickering, Ingrid J; Krone, Patrick H; George, Graham N

2013-08-19

158

Outer Planet Assessment Group (OPAG) Recommended Exploration Strategy for the Outer Planets 2013-2022  

Microsoft Academic Search

The Outer Solar System provides critical clues to how solar systems form and evolve, how planetary systems become habitable, and how life has evolved in our solar system. NASA's Outer Planets Assessment Group (OPAG) was established to identify scientific priorities and pathways for Outer Solar System exploration. Fundamental new discoveries are best made with a mixture of mission sizes that

William B. McKinnon

2010-01-01

159

Physics Flashlets: The Outer Solar System  

NSDL National Science Digital Library

This animation shows the orbits of the outer planets in the Solar System. This model of the outer solar system includes Jupiter, Saturn, Uranus, and Neptune. The paths of the planets are plotted and traced, and the user can see their relative speeds and periods to complete a full revolution.

Fowler, Michael; Welch, Heather

2008-09-24

160

Outer trapped surfaces in Vaidya spacetimes  

SciTech Connect

It is proven that in Vaidya spacetimes of bounded total mass, the outer boundary, in spacetime, of the region containing outer trapped surfaces, is the event horizon. Further, it is shown that the region containing trapped surfaces in these spacetimes does not always extend to the event horizon.

Ben-Dov, Ishai [Enrico Fermi Institute and Department of Physics, University of Chicago, 5640 S. Ellis Avenue, Chicago, Illinois 60637-1433 (United States)

2007-03-15

161

Exploring outer space technologies for sustainable buildings  

Microsoft Academic Search

Purpose – The purpose of this paper is to explore and identify the potential outer space technologies that can be used in the construction industry to enhance sustainability in buildings. Design\\/methodology\\/approach – Outer space technologies developed by the National Aeronautics and Space Administration (NASA) in the USA are explored for possible use in sustainable construction within the context of the

Sui Pheng Low; Xiu Ting Goh

2010-01-01

162

Liquid sodium model of Earth's outer core  

Microsoft Academic Search

Convective motions in Earth's outer core are responsible for the generation of the geomagnetic field. We present liquid sodium convection experiments in a spherical vessel, designed to model the convective state of Earth's outer core. Heat transfer, zonal fluid velocities, and properties of temperature fluctuations were measured for different rotation rates O and temperature drops DeltaT across the convecting sodium.

Woodrow Shew

2004-01-01

163

The Impact of Ceramic Shell Strength on Hot Tearing during Investment Casting  

NASA Astrophysics Data System (ADS)

The effect of ceramic shell strength on hot tearing susceptibility during solidification was inspected practicing investment casting of the cobalt-base superalloy samples with the same casting conditions, but different ceramic shell systems. Results showed that the lower the ceramic shell strength upon using polymer additives, the lower the hindered contraction rate, and the lower the hindered contraction rate, the smaller the hot tearing tendency. Optical microscopy and electron microscopy scanning revealed that the hot tear propagated along the last solidified interdendritic phase, and that the hot tear surface had two major modes: 1) the ductile region in the outer layer; and 2) the inner region of liquid embrittlement.

Norouzi, Saeid; Farhangi, Hassan

2011-01-01

164

Deformation of an elastic shell with variable thickness: a comparison of different methods  

NASA Astrophysics Data System (ADS)

Deformation of the outermost parts of single-plate planetary bodies is often modelled in terms of the response of a spherical elastic shell to surface or basal loading. As the thickness of such elastic lithosphere is usually much smaller than the radius of the body, the deformation is commonly approximated by that obtained for a thin elastic shell of uniform thickness. The main advantage of the thin shell approximation is its simplicity—the solution can be expressed analytically if the thickness of the shell is uniform, but even in the case of a thin shell of variable thickness, when the problem must be solved numerically, the computational costs are much lower than in a fully 3-D case. Here we analyse the error of the thin shell approximation by comparing it with the solution obtained for a shell of finite thickness using finite element methods. Special attention is paid to a shell of variable thickness and, in general, to the effect of elastic thickness variations on local deformation. For a shell of uniform thickness with the outer radius corresponding to Mars, we find that the error in radial displacement at low harmonic degrees (?? 20) does not exceed 5 per cent for small shell thicknesses (d? 50 km) and 10 per cent for thick shells (d˜ 250 km). Similar accuracy is also found for a shell of variable thickness if the thin shell approximation is used. Our numerical tests indicate that local deformation of a shell is mostly sensitive to the average thickness of the shell in the near zone while the effect of thickness variations in the far zone can be neglected in the first approximation. Consequently, the extremely simple thin shell method, designed for shells of uniform thickness, can be effectively used to obtain a reasonably accurate estimate of deflection even in the case of a shell with varying thickness. Finally, we investigate the deformation of an elastic lithosphere due to viscous flow beneath the shell, and we propose an extension of the concept, recently developed to correct dynamic topography for the effect of an elastic lithosphere, to the case of a shell of variable thickness.

Kalousová, K.; Sou?ek, O.; ?adek, O.

2012-08-01

165

Autoimmunity and the outer retina.  

PubMed

Structurally and therefore antigenically the retina is a complex tissue. Since it develops as an extension from the neural tube it shares with the brain several cell membranes and cytoplasm associated antigens including those present in neurofilaments of the various neurones and the glial filaments of the astrocytes. The advent of monoclonal antibodies has helped to dissect, in detail, the antigenic makeup of the retina. Nervous system antigens (NS-3, 4 and 7) are generously represented in the retina. At least in the chick eye there seems to be a concentration gradient of retinal antigens along a dorsoventral axis which is believed to provide means by which neurones of developing retinal signal and receive the positional information necessary for the formation of specific synapses. It now seems certain that organ-specific antigens are presented not only in the photoreceptors and the retinal pigment epithelium but also in the retinal ganglion cells and the astrocytes. Photoreceptor outer-segment contains soluble antigens which when injected in rats, rabbits, guinea-pigs or monkeys produce varying degrees of intraocular inflammation leading to uveitis, retinal detachment, photoreceptor degeneration and occasionally retinal vasculitis. Both cell-mediated and humoral immunity to photoreceptor antigen has been demonstrated in various types of uveitis (including toxoplasmosis and sarcoidosis), pars planitis, vitriitis, Behçets disease, sympathetic ophthalmitis, Vogt-Koyanagi-Harada syndrome, birdshot retinopathy, retinitis pigmentosa and retinal vasculitis. Retinal autoimmunity is also found in retinal detachment and diabetic retinopathy, particularly after Argon laser photocoagulation. Antibodies to retinal antigens are also found in patients with systemic lupus erythematosus and other systemic immune disorders without ocular involvement. The precise pathogenetic role of retinal autoimmunity in eye disease is therefore uncertain. It may simply represent an epiphenomenon which develops afer retinal damage due to physical, micro-organismal or immunological insult. Alternatively it is possible that although autoimmunity does not initiate ocular inflammation it perpetuates and maintains the inflammatory state and produces further damage to ocular tissues. PMID:6611615

Rahi, A H; Addison, D J

1983-01-01

166

Hard diffraction in CDF  

SciTech Connect

The aim of these studies is to use hard (large Q{sup 2}) processes to investigate the partonic nature of the pomeron. We have measured events with large rapidity gaps between balancing high E{sub T} jets, events with two forward (same-side) jets and a large gap (diffractive di-jet production), diffractive W{sup {+-}} production and diffractive heavy flavor (J/{psi} and b-quark) production. Candidate events of the type double-pomeron {yields} di-jet are observed. I close with a look at the future (Run II).

Albrow, M.G.; CDF Collaboration

1997-10-01

167

Hard metal composition  

DOEpatents

A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 weight percent boron carbide and the remainder a metal mixture comprising from 70 to 90 percent tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 to 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

Sheinberg, Haskell (Los Alamos, NM)

1986-01-01

168

FABRICATION OF A NEW TYPE OF DOUBLE SHELL TARGET HAVING A PVA INNER LAYER  

SciTech Connect

OAK-B135 The General Atomics Target Fabrication team was tasked in FY03, under its ICF Target Support contract, to make a new type of double-shell target. its specifications called for the outer shell to have an inner lining of PVA (poly(vinyl alcohol)) that would keep the xenon gas fill from occupying the target wall. The inner shell consisted of a glass shell coated with 2000 {angstrom} of silver and filled with 9 atm of deuterium. Furthermore, the delivery deadline was less than seven weeks away. This paper describes the fielding of this double-shell target, made possible through the combined efforts of Lawrence Livermore National Laboratory and General Atomics target fabrication specialists.

STEINMAN,D.A; WALLACE,R; GRANT,S.E; HOPPE,M.L; SMITH,JR.J.N

2003-06-01

169

Hard Metal Disease  

PubMed Central

In Great Britain there have been no published reports of respiratory disease occurring amongst workers in the hard metal (tungsten carbide) industry. In this paper the clinical and radiological findings in six cases and the pathological findings in one are described. In two cases physiological studies indicated mild alveolar diffusion defects. Histological examination in a fatal case revealed diffuse pulmonary interstitial fibrosis with marked peribronchial and perivascular fibrosis and bronchial epithelial hyperplasia and metaplasia. Radiological surveys revealed the sporadic occurrence and low incidence of the disease. The alterations in respiratory mechanics which occurred in two workers following a day's exposure to dust are described. Airborne dust concentrations are given. The industrial process is outlined and the literature is reviewed. The toxicity of the metals is discussed, and our findings are compared with those reported from Europe and the United States. We are of the opinion that the changes which we would describe as hard metal disease are caused by the inhalation of dust at work and that the component responsible may be cobalt. Images

Bech, A. O.; Kipling, M. D.; Heather, J. C.

1962-01-01

170

Testing and analysis to determine the shell thickness required to prevent puncture  

Microsoft Academic Search

Type B radioactive material packages are required to withstand a hypothetical puncture accident of a free fall from a height of one meter onto a 15 cm diameter mild steel puncture probe. For many packages it is desirable to have this accident event not result in puncture or tearing of the outer shell of the package. The wall thickness necessary

D. J. Ammerman; H. D. Radloff; E. J. Eifert

1998-01-01

171

Induction of through-thickness temperature gradients in thin shell ceramic composite cylinders by thermal radiation  

Microsoft Academic Search

Silicon carbide matrix composites are candidate materials to serve as high-temperature combustor liners. This application exposes the liner to thermal gradients through the thickness which contribute major sources of stress. To evaluate the liner’s potential performance, thermal gradients were induced with an axisymmetric, direct current, electric arc lamp within the cylinder. Simultaneously, the outer surface of the shell was cooled

J. C. Goldsby; M. C. Halbig

2001-01-01

172

The outer disks of nearby galaxies  

NASA Astrophysics Data System (ADS)

This dissertation presents three observational projects designed to characterize the outer disks of nearby galaxies (beyond the optical radius R25). Until very recently, outer disks remained an elusive and poorly-understood component of disk galaxies. We first present a Large Binocular Telescope (LBT) optical imaging survey of nearby outer disks to examine the basic properties of this component. Our LBT observations indicate that most nearby galaxies host an outer disk with star formation occurring at a very low level. We detect hundreds of outer disk star clusters and show that they typically have masses between 100--10,000 solar masses and ages up to a Gyr. The clusters are born in groups that can remain clustered for a Gyr or more, while the clusters slowly evaporate stars into a diffuse stellar component. The clusters appear to form from localized overdensities in the gas distribution primarily associated with spiral structure. The clusters extend to 2R25 in our sample. We find that some clusters may also reside well outside of their host galaxy's gas disk. Our second project is a kinematic study of H-alpha knots in the outer disk of the large, isolated, face-on galaxy NGC 628, using Inamori Magellan Areal Camera and Spectrograph (IMACS) observations from the Magellan telescope. This galaxy shows a kinematically cold outer disk (velocity dispersion < 11 km/s) with a mass density Sigma = 7.5 solar masses per square pc. Our observations cannot exclude uniform star formation lasting a Hubble time in this outer disk and confirm that this component is an extension of the kinematically-cold inner disk. Our third project is a search for molecular emission in the outer disk of NGC 628, using the sensitive Atacama Large Millimeter Array (ALMA) receiver on the Submillimeter Telescope (SMT). We did not detect emission from our outer disk pointings, though we are able to provide useful estimates for future ALMA observations of outer disk knots. Our SMT observations indicate that the H2 / HI ratio is ˜100x lower in the outer disk than in the inner disk, which likely explains, at least in part, the trend towards smaller clusters and lower star formation rates at larger radii.

Herbert-Fort, Stephane

173

Multicolor photometry of outer Jovian satellites  

NASA Astrophysics Data System (ADS)

Multicolor photometry was obtained of satellites J6 Himalia, J7 Elara, and J10 Lysithea in the prograde cloud of outer Jovian satellites, and of J8 Pasiphae, J9 Sinope, and J11 Carme in the retrograde cloud. The data for J9 are fragmentary; otherwise, the satellites all look like C-class asteroids, except J11, which shows a remarkable brightness in the ultraviolet. The absence of D-class spectra among the outer Jovian satellites suggests that they were not derived from the same population as the outer-belt and Trojan asteroid populations.

Tholen, D. J.; Zellner, B.

1984-05-01

174

Core–shell structured and electro-magnetic functionalized polyaniline composites  

Microsoft Academic Search

Core–shell structured and electro-magnetic functionalized polyaniline (PANI) composites were chemically prepared by micro-spherical hydroxyl iron (Fe(OH)) magnet as the hard-template associated with a self-assembly process in the presence of ?-naphthalene sulfonic acid (?-NSA) as the dopant. Field emitting scanning electron microscope (SEM) and transmission electron microscope (TEM) measurements indicate that the electro-magnetic functionalized PANI–?-NSA\\/Fe(OH) composites have a novel core–shell structure,

Xin Li; Jiaoyan Shen; Meixiang Wan; Zhaojia Chen; Yen Wei

2007-01-01

175

Thin plastic shell x-ray optics: an update  

NASA Astrophysics Data System (ADS)

We present new results from a program to develop large area X-ray telescopes that are made from thin plastic shells. We use multi-shell cylindrical lenses in a point-to-point configuration to form full aperture images of the small focal spot in a an X-ray tube on a microchannel plate detector. The image data are analyzed to yield radial profiles and encircled energy curves. The derived parameters can be extrapolated to the case of a telescope that is a conical approximation to Wolter 1 optics. The plastic shells can be coated with suitable mono- or multilayers that allow for a wideband coverage of X-ray energies. Our current program is focused on the development of a large area, hard X-ray telescope for a balloon payload.

Schnopper, Herbert W.; Barbera, Marco; Silver, Eric H.; Ingram, Russell H.; Christensen, Finn E.; Romaine, Suzanne E.; Cohen, Lester M.; Collura, Alfonso; Murray, Stephen S.

2003-03-01

176

Review of Recovery and Recolonization of Hard Substrate Communities of the Outer Continental Shelf.  

National Technical Information Service (NTIS)

The 1-page report summarizes knowledge of how marine benthic communities off California respond to both natural and anthropogenic disturbances. The results from the study will aid the MMS in making environmental assessments and management decisions associ...

A. Lissner

1988-01-01

177

Review of recovery and recolonization of hard substrate communities of the Outer Continental Shelf. Final report  

SciTech Connect

This report summarizes knowledge of how marine benthic communities off California respond to both natural and anthropogenic disturbances. The results from the study will aid the MMS in making environmental assessments and management decisions associated with potential oil and gas leasing, exploration, and development activities. The objectives of the report on recovery and recolonization are: (1) to review relevant recovery and recolonization studies, pertinent life-history information, and data gaps.

Lissner, A.

1988-06-01

178

Acidic Shell Proteins of the Mediterranean Fan Mussel Pinna nobilis.  

PubMed

In molluscs, the shell secretion process is controlled by a set of extracellular macromolecules collectively called the shell matrix. The shell matrix, which is produced by the mantle epithelial cells during mineralization, is predominantly composed of proteins, glycoproteins, acidic polysaccharides, and chitin that precisely regulate the deposition of calcium carbonate outside the mantle cells. In the present paper, we focus on the shell of Pinna nobilis, the giant Mediterranean fan mussel, usually considered as a model for studying molluscan biomineralization processes. P. nobilis exhibits indeed a nacro-prismatic shell, the outer layer of which is constituted of the so-called "regular simple calcitic prisms," according to Carter and Clark (1985). We review here the microstructural characteristics of the prisms and nacre and the biochemical properties of their associated matrices. In particular, the calcitic prisms of P. nobilis are characterized by a cortege of unusually acidic intraprismatic proteins, while the ones of the nacreous layer seem less acidic. A brief description of the molecular characterization of three acidic proteins, caspartin, calprismin and mucoperlin, is given. In particular, we show that extremely acidic intracrystalline proteins such as caspartin interact with calcium carbonate at different scales, from micrometric to crystal lattice levels. PMID:21877273

Marin, Frédéric; Narayanappa, Prabakaran; Motreuil, Sébastien

2011-01-01

179

Golden Rule of Radiation Hardness: a Study of Strain Effect on Controlled Radiation Damage  

NASA Astrophysics Data System (ADS)

Stain is widely presented in microstructures. Strain effect to radiation hardness is critical in understanding and engineering nano-materials. Here we studied the strain effect on the controlled radiation damage in monolayer hexagonal boron nitride (h-BN) through ab initio density functional theory calculations. We observed a general behavior of reduction in the radiation hardness by the strain, for both B-vacancy and N-vacancy configurations, in both compressive and tensive strain states, at the directions of zigzag, armchair and bi-axial. We proposed a golden rule of the radiation hardness states that any effort adding energy to the system will reduce the radiation hardness. Such golden rule of radiation hardness could be widely applied to material design and engineering for those devices working in irradiation-enrich environments, for example, electronic and optoelectronic devices in outer space.

Peng, Qing; Ji, Wei; de, Suvranu

2012-02-01

180

The role of the zebra mussel ( Dreissena polymorpha ) in structuring macroinvertebrate communities on hard substrata  

Microsoft Academic Search

We examined the importance of the Eurasian zebra mussel (Dreissena polymorpha) in structuring macroinvertebrate communities on hard substrata in the Great Lakes - St. Lawrence River system. An experiment using artificial substrata (i.e., cement bricks with either a layer of living zebra mussels, a layer of intact empty shells that mimicked living mussels, or with no added layer) showed that

Anthony Ricciardi; Fred G. Whoriskey; Joseph B. Rasmussen

1997-01-01

181

Nuclear Shell Structure  

Microsoft Academic Search

The existence of closed shells in nuclei is indicated by the particular stability and abundance of nuclear systems with certain numbers of neutrons and of protons. An interesting correspondence exists between these numbers and the degeneracy of energy levels in the model of free particles in a simple rectangular potential well. The empirical relations suggest the addition of a central

Eugene Feenberg; Kenyon C. Hammack

1949-01-01

182

Shell Creek Summers  

ERIC Educational Resources Information Center

|In 2002 Shell Creek Watershed Improvement Group turned to the Newman Grove Public Schools' science department to help educate the public on water quality in the watershed and to establish a monitoring system that would be used to improve surface and groundwater quality in the creek's watershed. Nebraska Department of Environmental Quality…

Seier, Mark; Goedeken, Suzy

2005-01-01

183

Snail Shell Science.  

ERIC Educational Resources Information Center

|Presents three inquiry-based lessons to develop the science process skills of observation, identification, and classification. Activities use whelk eggs and snail shells as the focus of the students' inquiries. Provides a list of 19 facts about whelks and snails. (MDH)|

Matthews, Catherine

1992-01-01

184

Agreement, Shells, and Focus.  

ERIC Educational Resources Information Center

Reconsiders development and licensing of agreement as a syntactic projection and argues for a productive developmental relation between agreement and the category of focus. Suggests that focus projections are initially selected by a variety of functional heads with real semantic content, then, over time decays into a simple concord shell. Upon…

Simpson, Andrew; Wu, Zoe

2002-01-01

185

Shell Creek Summers  

ERIC Educational Resources Information Center

In 2002 Shell Creek Watershed Improvement Group turned to the Newman Grove Public Schools' science department to help educate the public on water quality in the watershed and to establish a monitoring system that would be used to improve surface and groundwater quality in the creek's watershed. Nebraska Department of Environmental Quality provided…

Seier, Mark; Goedeken, Suzy

2005-01-01

186

Automorphisms of Free Groups and Outer Space  

Microsoft Academic Search

This is a survey of recent results in the theory of automorphism groups of finitely-generated free groups, concentrating on results obtained by studying actions of these groups on Outer space and its variations.

Karen Vogtmann

2002-01-01

187

Mycobacterial outer membranes: in search of proteins  

PubMed Central

Summary The cell wall is a major virulence factor of Mycobacterium tuberculosis and contributes to its intrinsic drug resistance. Recently, cryo-electron microscopy showed that the mycobacterial cell wall lipids form an unusual outer membrane. Identification of the components of the uptake and secretion machinery across this membrane is critical for understanding the physiology and pathogenicity of M. tuberculosis and for the development of better anti-tuberculosis drugs. Although the genome of M. tuberculosis appears to encode over 100 putative outer membrane proteins, only a few have been identified and characterized. Here, we summarize the current knowledge on the structure of the mycobacterial outer membrane and its known proteins. Through comparison to transport processes in Gram-negative bacteria, we highlight several hypothetical outer membrane proteins of M. tuberculosis awaiting discovery.

Niederweis, Michael; Danilchanka, Olga; Huff, Jason; Hoffmann, Christian; Engelhardt, Harald

2010-01-01

188

Cosmic ray gradients in the outer heliosphere.  

NASA Astrophysics Data System (ADS)

Pioneer 10 and 11 spacecraft are now probing the outer heliosphere. The authors have used the UCSD instruments on board to study the gradient, and to look at the time and spatial variations of the cosmic ray intensities.

Fillius, W.; Wake, B.; Ip, W.-H.; Axford, I.

1983-08-01

189

7 CFR 51.2002 - Split shell.  

Code of Federal Regulations, 2013 CFR

...51.2002 Split shell. Split shell means a shell having any crack which is open and conspicuous for a distance of more than one-fourth the circumference of the shell, measured in the direction of the...

2013-01-01

190

Outer Billiards and the Pinwheel Map  

Microsoft Academic Search

In this paper we establish a kind of bijection between the orbits of a\\u000apolygonal outer billiards system and the orbits of a related (and simpler to\\u000aanalyze) system called the pinwheel map. One consequence of the result is that\\u000athe outer billiards system has unbounded orbits if and only if the pinwheel map\\u000ahas unbounded orbits. As the pinwheel

Richard Evan Schwartz

2010-01-01

191

Planetary Aeronomy of the Outer Solar System  

NASA Astrophysics Data System (ADS)

This talk will give a historical tour of the highlights of my research on atmospheres in the outer solar system and their interaction with the magnetospheric plasma. Topics include atmospheric photochemistry, the Io plasma torus, the Galilean satellites, and the nitrogen atmospheres on Titan, Triton, and Pluto. The important role of observations combined with theory will be emphasized. The talk will finish with current research on the role that atmospheric escape plays on atmospheric structure in the outer solar system.

Strobel, Darrell

2012-10-01

192

[Hard metal interstitial lung disease].  

PubMed

Hard metal lung disease is an unusual disease which can occur in individuals exposed to hard metals. Clinically, the condition resembles hypersensitivity pneumonitis depending mainly on individual susceptibility, which eventually progresses to pulmonary fibrosis. We present two patients with pulmonary fibrosis, who were actually diagnosed after an exhaustive anamnesis and examination of the tissue by scanning microscope to discard hard metals. The evaluation of wedge biopsies by scanning electronic microscope can be very helpful in those cases without a specific diagnosis. PMID:19962814

Montero, M Angeles; de Gracia, Javier; Morell, Ferràn

2009-12-04

193

Diffusion welding of hard alloys  

Microsoft Academic Search

1.The hot pressing method, which is characterized by induction heating in graphite dies, can be used for the diffusion welding of tungsten-cobalt hard alloys and the “baking-on” of new hard-alloy layers consisting of hard-alloy powder mixtures.2.Mechanical tests have shown that the strength secured by means of diffusion welding at 1400° according to the proposed method approaches the strength of the

K. S. Gerasimenko; S. I. Spirina

1967-01-01

194

Sea shells and blood cells  

NSDL National Science Digital Library

Scientists know that oysters make their shells from crystals but where the crystals are made is still a mystery. A new study in the 09 April 2004 issue of the journal Science suggests that these shell-building crystals are formed in a special class of blood cells that travel to the site of shell formation and unload their crystal cargo.

American Association for the Advancement of Science (AAAS;)

2004-04-09

195

Extending synchrotron-based atomic physics experiments into the hard X-ray region  

SciTech Connect

The high-brightness, hard x-ray beams available from third-generation synchrotron sources are opening new opportunities to study the deepest inner shells of atoms, an area where little work has been done and phenomena not observed in less tightly bound inner-shells are manifested. In addition scattering processes which are weak at lower energies become important, providing another tool to investigate atomic structure as well as an opportunity to study photon/atom interactions beyond photoabsorption. In this contribution the authors discuss some of the issues related to extending synchrotron-based atomic physics experiments into the hard x-ray region from the physical and the experimental point of view. They close with a discussion of a technique, resonant Raman scattering, that may prove invaluable in determining the spectra of the very highly-excited states resulting from the excitation of deep inner shells.

LeBrun, T. [Argonne National Lab., IL (United States). Physics Div.

1996-12-31

196

Microstructure, Composition, and Hardness of Rockwell C Hardness Blocks.  

National Technical Information Service (NTIS)

The microstructure, composition, and hardness of hardness blocks (Rockwell C scale) that are commonly available in the country were examined. Blocks near HRC levels of 25, 45, and 65 were obtained from each of six sources to represent the HRC measurement ...

T. A. Siewert A. Tomer

1991-01-01

197

Shape evolution of a core-shell spherical particle under hydrostatic pressure.  

PubMed

The morphological evolution by surface diffusion of a core-shell spherical particle has been investigated theoretically under hydrostatic pressure when the shear modulii of the core and shell are different. A linear stability analysis has demonstrated that depending on the pressure, shear modulii, and radii of both phases, the free surface of the composite particle may be unstable with respect to a shape perturbation. A stability diagram finally emphasizes that the roughness development is favored in the case of a hard shell with a soft core. PMID:22587137

Colin, Jérôme

2012-03-30

198

Bioluminescent signals spatially amplified by wavelength-specific diffusion through the shell of a marine snail  

PubMed Central

Some living organisms produce visible light (bioluminescence) for intra- or interspecific visual communication. Here, we describe a remarkable bioluminescent adaptation in the marine snail Hinea brasiliana. This species produces a luminous display in response to mechanical stimulation caused by encounters with other motile organisms. The light is produced from discrete areas on the snail's body beneath the snail's shell, and must thus overcome this structural barrier to be viewed by an external receiver. The diffusion and transmission efficiency of the shell is greater than a commercial diffuser reference material. Most strikingly, the shell, although opaque and pigmented, selectively diffuses the blue-green wavelength of the species bioluminescence. This diffusion generates a luminous display that is enlarged relative to the original light source. This unusual shell thus allows spatially amplified outward transmission of light communication signals from the snail, while allowing the animal to remain safely inside its hard protective shell.

Deheyn, Dimitri D.; Wilson, Nerida G.

2011-01-01

199

Thickness constraints on the icy shells of the galilean satellites from a comparison of crater shapes.  

PubMed

A thin outer ice shell on Jupiter's large moon Europa would imply easy exchange between the surface and any organic or biotic material in its putative subsurface ocean. The thickness of the outer ice shell is poorly constrained, however, with model-dependent estimates ranging from a few kilometres to ten or more kilometres. Here I present measurements of depths of impact craters on Europa, Ganymede and Callisto that reveal two anomalous transitions in crater shape with diameter. The first transition is probably related to temperature-dependent ductility of the crust at shallow depths (7 8 km on Europa). The second transition is attributed to the influence of subsurface oceans on all three satellites, which constrains Europa's icy shell to be at least 19 km thick. The icy lithospheres of Ganymede and Callisto are equally ice-rich, but Europa's icy shell has a thermal structure about 0.25 0.5 times the thicknesses of Ganymede's or Callisto's shells, depending on epoch. The appearances of the craters on Europa are inconsistent with thin-ice-shell models and indicate that exchange of oceanic and surface material could be difficult. PMID:12024207

Schenk, Paul M

2002-05-23

200

Measuring the Hardness of Minerals  

ERIC Educational Resources Information Center

|The author discusses Moh's hardness scale, a comparative scale for minerals, whereby the softest mineral (talc) is placed at 1 and the hardest mineral (diamond) is placed at 10, with all other minerals ordered in between, according to their hardness. Development history of the scale is outlined, as well as a description of how the scale is used…

Bushby, Jessica

2005-01-01

201

Nonconventional Hard-Metal Compositions.  

National Technical Information Service (NTIS)

A novel hard-metal composition comprising borides and carbides of tungsten, nickel, and iron is made by reaction hot-pressing mixtures of elemental tungsten, nickel, and iron powders with small quantities of boron carbide. The hardness of these compositio...

H. Sheinberg

1982-01-01

202

Hard Disk Drive Manufacturing Optimization  

Microsoft Academic Search

Rapid increase in demand for high hard disk data storage density is forcing R&D centers and manufacturing companies to focus on continuous improvement of hard disk drive (HDD) performance. Current HDD records data on the magnetic disk or platter by controlling a magnetizing ferromagnetic material directionally. The data are read from the disk using a magnetic head by detecting the

Riadh Zaier; Jamil Abdo

2012-01-01

203

Rheological Properties of Water Ice-Applications to Satellites of the Outer Planets  

NASA Astrophysics Data System (ADS)

The icy moons of the outer solar system have not been quiescent bodies, in part because many have a substantial water component and have experienced significant internal heating. We can begin to understand the thermal evolution of the moons and the rate of viscous relaxation of surface topography because we now have good constraints on how ice (in several of its polymorphic forms) flows under deviatoric stress at planetary conditions. Details of laboratory-derived flow laws for pure, polycrystalline ice are reviewed in detail. One of the more important questions at hand is the role of ice grain size. Grain size may be a dynamic quantity within the icy moons, and it may (or may not) significantly affect rheology. One recent beneficiary of revelations about grain-size-sensitive flow is the calculation of the rheological structure of Europa's outer ice shell, which may be no thicker than 20 km.

Durham, W. B.; Stern, L. A.

204

Bioerosion of gastropod shells: with emphasis on effects of coralline algal cover and shell microstructure  

NASA Astrophysics Data System (ADS)

Organisms boring into fifty nine species of gastropod shells on reefs around Guam were the bryozoan Penetrantia clionoides; the acrothoracian barnacles Cryptophialus coronorphorus, Cryptophialus zulloi and Lithoglyptis mitis; the foraminifer Cymbaloporella tabellaeformis, the polydorid Polydora sp. and seven species of clionid sponge. Evidence that crustose coralline algae interfere with settlement of larvae of acrothoracian barnacles, clionid sponges, and boring polychaetes came from two sources: (1) low intensity of boring in limpet shells, a potentially penetrable substrate that remains largely free of borings by virtue of becoming fully covered with coralline algae at a young age and (2) the extremely low levels of boring in the algal ridge, a massive area of carbonate almost entirely covered by a layer of living crustose corallines. There was a strong negative correlation between microstructural hardness and infestation by acrothoracian barnacles and no correlation in the case of the other borers. It is suggested that this points to a mechanical rather than a chemical method of boring by the barnacles. The periostracum, a layer of organic material reputedly a natural inhibitor of boring organisms, was bored by acrothoracican barnacles and by the bryozoan. The intensity of acrothoracican borings is shown to have no correlation with the length of the gastropod shell.

Smyth, Miriam J.

1989-12-01

205

A split in the outer radiation belt by magnetopause shadowing: Test particle simulations  

NASA Astrophysics Data System (ADS)

We developed a three-dimensional relativistic test particle code and used it to calculate the trajectories of relativistic electrons in the outer radiation belt. By applying time-varying magnetic field data calculated from the Tsyganenko model and using observed solar wind data and the Dst index, we examined the drift loss of relativistic electrons by magnetopause shadowing (MPS). Since other loss processes such as wave-particle interactions are not included in this simulation, the pure MPS effect can be discussed. A split was found in the outer radiation belt after the enhancement of the solar wind dynamic pressure. Isolated electrons outside of the split have a narrow pitch angle distribution around 90° and are confined to a narrow range of the L shell. We found that the existence of the isolated electrons depends on the large geomagnetic tilt angle. These findings indicate that the split can be seen during summer and winter after MPS occurs. We suggest that this split in the outer radiation belt during summer and winter is evidence that MPS actually causes the loss of the outer radiation belt.

Saito, S.; Miyoshi, Y.; Seki, K.

2010-08-01

206

Design and synthesis of highly luminescent near-infrared-emitting water-soluble CdTe/CdSe/ZnS core/shell/shell quantum dots.  

PubMed

Applications of water-dispersible near-infrared (NIR)-emitting quantum dots (QDs) have been hampered by their instability and low photoluminescence (PL) efficiencies. In this paper, water-soluble highly luminescent NIR-emitting QDs were developed through constructing CdTe/CdSe/ZnS core/shell/shell nanostructure. The CdTe/CdSe type-II structure yields the QDs with NIR emission. By varying the size of CdTe cores and the thickness of the CdSe shell, the emission wavelength of the obtained nanostructure can span from 540 to 825 nm. In addition, the passivation of the ZnS shell with a substantially wide bandgap confines the excitons within the CdTe/CdSe interface and isolates them from the solution environment and consequently improves the stability of the nanostructure, especially in aqueous media. An effective shell-coating route was developed for the preparation of CdTe/CdSe core/shell nanostructures by selecting capping reagents with a strong coordinating capacity and adopting a low temperature for shell deposition. An additional ZnS shell was deposited around the outer layer of CdTe/CdSe QDs to form the core/shell/shell nanostructure through the decomposition of single molecular precursor zinc diethyldithiocarbamate in the crude CdTe/CdSe reaction solution. The water solubilization of the initially oil-soluble CdTe/CdSe/ZnS QDs was achieved through ligand replacement by 3-mercaptopropionic acid. The as-prepared water-soluble CdTe/CdSe/ZnS QDs possess PL quantum yields as high as 84% in aqueous media, which is one of the best results for the luminescent semiconductor nanocrystals. PMID:19772326

Zhang, Wenjin; Chen, Guanjiao; Wang, Jian; Ye, Bang-Ce; Zhong, Xinhua

2009-10-19

207

Baseline Microstructural Characterization of Outer 3013 Containers  

SciTech Connect

Three DOE Standard 3013 outer storage containers were examined to characterize the microstructure of the type 316L stainless steel material of construction. Two of the containers were closure-welded yielding production-quality outer 3013 containers; the third examined container was not closed. Optical metallography and Knoop microhardness measurements were performed to establish a baseline characterization that will support future destructive examinations of 3013 outer containers in the storage inventory. Metallography revealed the microstructural features typical of this austenitic stainless steel as it is formed and welded. The grains were equiaxed with evident annealing twins. Flow lines were prominent in the forming directions of the cylindrical body and flat lids and bottom caps. No adverse indications were seen. Microhardness values, although widely varying, were consistent with annealed austenitic stainless steel. The data gathered as part of this characterization will be used as a baseline for the destructive examination of 3013 containers removed from the storage inventory.

Zapp, Phillip E.; Dunn, Kerry A

2005-07-31

208

Shell model calculations of 109Sb in the sdgh shell  

NASA Astrophysics Data System (ADS)

The energy spectra of the antimony isotope 109Sb in the sdgh shell are calculated in the nuclear shell model approach by using the CD-Bonn nucleon-nucleon interaction. The modified Drexel University parallel shell model code (DUPSM) was used for the calculations with maximum Hamiltonian dimension of 762 253 of 5.14% sparsity. The energy levels are compared to the recent experimental results. The calculations were done on the Cyborg Parallel Cluster System at Drexel University.

Dikmen, E.; Novoselsky, A.; Vallieres, M.

2001-12-01

209

The Oxidant Thimerosal Modulates Gating Behavior of KCNQ1 by Interaction with the Channel Outer Shell  

Microsoft Academic Search

Thimerosal (o-Ethylmercurithio)benzoic acid, TMS), a membrane-impermeable, sulfhydryl-oxidizing agent, has been described to increase the K+ current IKs in KCNE1-injected Xenopus laevis oocytes. Since there are no cysteine residues in the extracellular domain of KCNE1, it has been proposed that TMS interacts with its partner protein KCNQ1. The aim of this study was therefore to investigate the interaction of TMS with

G. Kerst; H. Brousos; R. Schreiber; R. Nitschke; M. J. Hug; R. Greger; M. Bleich

2002-01-01

210

Neutrino-induced Neucleosynthesis in Supernova Helium Shells  

NASA Astrophysics Data System (ADS)

We re-examine a neutrino-driven r-process mechanism in the helium shell of a core-collapse supernova. We analyze the pre-shock evolution in detail using recent stellar models. In addition we perform full hydrodynamic simulations including the effect of shock, finding that the outer helium shells can be the site for an r-process. We find that this mechanism could succeed in early stars of metallicity ? 10-3 the solar value, at relatively low temperatures and neutron densities, producing A ˜ 130 and 195 abundance peaks over ˜ 50--60 s. The mechanism is extremely sensitive to the neutrino emission model and to neutrino oscillations. While this mechanism is not very sensitive to the explosion energy, mixing of the ejecta can be different for different explosion energies. We discuss the implications of an r-process that could alter interpretations of abundance data from metal-poor stars.

Banerjee, Projjwal

211

Titan exploration in the Outer Planets Program  

NASA Astrophysics Data System (ADS)

Although the next NASA Outer Planets Flagship Mission is expected to be directed to the Jovian system focusing on Europa, Titan after Cassini-Huygens remains a high priority target of interest due to its parallels with the Earth (including weather) and potential for astrobiology. This talk will discuss the possibilities for future robotic exploration of Titan in the context of the NASA Outer Planets Program, including Discovery and New Frontiers-class spacecraft, and the necessary precursor activities to missions such as technology development.

Niebur, Curt

2010-04-01

212

Continuum Mechanical Model of the Outer Hair Cell  

NASA Astrophysics Data System (ADS)

Knowledge of the mechanical properties of the outer hair cell (OHC) is essential for understanding its electromechanical action. To provide insight into underlying mechanics, we developed a finite-element-model of the OHC. The model contains both an intracellular viscous fluid and a homogeneous shell-like structure for the basolateral wall, including anisotropic viscoelastic material properties. We found that the viscosity of the intracellular fluid could not yield the frequency dependent behaviour of the measured impedance. Shear viscosity needed to be included in the basolateral wall to obtain an adequate representation. The required value of the dynamic viscosity is on the order of 103 mPa.s and, therefore, 1000 fold higher than for water. Furthermore, changing the compressibility of the basolateral wall from 106 to 109 Pa suggests that the impedance is not significantly affected by this parameter. Finally, our calculations indicate that up to at least 10 kHz the measured impedances result from passive mechanical properties of the OHC.

Fleischer, Mario; Harasztosi, Csaba; Nowotny, Manuela; Zahnert, Thomas; Gummer, Anthony W.

2011-11-01

213

Fabrication and catalytic performance of highly stable multifunctional core-shell zeolite composites.  

PubMed

Multifunctional Fe3O4@SiO2-Au@silicalite-1 core-shell magnetic zeolite composites were fabricated by combining a series of sol-gel process and vapor-phase transfer of silicalite-1 zeolite nanocrystal-seeded silica shells. The obtained composite has high magnetization (32.00 emu/g), stably confined and active gold nanoparticles (ca. 15 nm), and a hierarchical silicalite-1 outer shell. The core-shell composite exhibits a high efficiency of magnetic separability, excellent catalytic performance, and reusability for the reduction of 4-nitrophenol with conversion of 98% in 12 min. Moreover, it preserves a good stability after a high-temperature hydrothermal treatment. PMID:24041421

Wang, Xiaofang; Cui, Yuanzheng; Wang, Yang; Song, Xiaowei; Yu, Jihong

2013-09-16

214

Fabrication of bifunctional core-shell Fe3O4 particles coated with ultrathin phosphor layer  

NASA Astrophysics Data System (ADS)

Bifunctional monodispersed Fe3O4 particles coated with an ultrathin Y2O3:Tb3+ shell layer were fabricated using a facile urea-based homogeneous precipitation method. The obtained composite particles were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), quantum design vibrating sample magnetometry, and photoluminescence (PL) spectroscopy. TEM revealed uniform spherical core-shell-structured composites ranging in size from 306 to 330 nm with a shell thickness of approximately 25 nm. PL spectroscopy confirmed that the synthesized composites displayed a strong eye-visible green light emission. Magnetic measurements indicated that the composite particles obtained also exhibited strong superparamagnetic behavior at room temperature. Therefore, the inner Fe3O4 core and outer Y2O3:Tb3+ shell layer endow the composites with both robust magnetic properties and strong eye-visible luminescent properties. These composite materials have potential use in magnetic targeting and bioseparation, simultaneously coupled with luminescent imaging.

Atabaev, Timur Sh; Kim, Hyung-Kook; Hwang, Yoon-Hwae

2013-08-01

215

Prevention of the Outer Space Weaponization  

NASA Astrophysics Data System (ADS)

9 states. The satellites of various functions (early warning, communication, data acquisition, reconnaissance and navigation) were actively used and continue to be used with the purposes of raising efficiency of ground armed forces, especially in fight against international terrorism. At the same time such satellites are not a weapon in the sense of that word since they do not create the threats of armed attack in outer space or from outer space. Moreover, they promote maintaining of stability in the international relations. For this reason the reconnaissance and data acquisition satellites used for the verification of observance by States of the arms limitation agreements are under international protection as national technical means of the control. Similar protection is enjoyed by the early warning satellites. With the help of space communication facilities the more reliable operative connection of the statesmen is organized in the strained situations. By this way the probability of making of the incorrect retaliatory decisions in critical political situations is reduced. At the same time it's necessary to take into consideration that the activities of such satellite systems are tightly connected with ground armed forces of the states. the earth, what from the point of view of international law may be qualified as establishing a partial demilitarization regime in outer space. After the prohibition of anti-satellite weapons (ASAT) and anti-satellite (ASAT) weapons it will be possible to speak about establishing of an international legal regime of complete demilitarization in outer space eliminating any kinds of weapon from outer space. in a peaceful time. weaponization.The main task of this paper is to analyze and to discuss the present binding regime of the outer space deweaponization and particular measures on consolidation and strengthening of this regime. agreements of the Russian Federation and the USA into multilateral Treaties. Such "immunity" would cover all operating space objects, irrespective of their military or civil designation. This approach is quite justified taking into consideration that military sattelites enhanced international peace and security and had broad advantages, such as treaty compliance and monitoring, the global positioning system, counter-terrorism and sanctions enforcement. Many examples of the last years demonstrate the tendency of engagement of military satellites into commercial space services. transparency on the pre-launch stage of space activity, including satellite inspection before ignition. Objects Flight Path Tracking. implemantation of a non-use of force and threat of force - a fundamental principle of modern international law. This implies the application of the menshened principle of international law by means of a treaty to the outer space activities with reference to the actions made in outer space, or directed from outer space against targets on the Earth as well as directed from the Earth against objects moving in outer space. to the possibility of conclusion in future of a multilateral arrangement on the prohibition of the space-based ABM. Accordingly, it is discussed the problem of an efficient international control over the prohibition of placement of the above mentioned weapons into outer space. to the challenges of the new millennium. 8

Zhukov, Gennady P.

2002-01-01

216

Isolation and Characterization of the Outer Membrane of Borrelia hermsii  

Microsoft Academic Search

The outer membrane of Borrelia hermsii has been shown by freeze-fracture analysis to contain a low density of membrane-spanning outer membrane proteins which have not yet been isolated or identified. In this study, we report the purification of outer membrane vesicles (OMV) from B. hermsii HS-1 and the subsequent identification of their constituent outer membrane proteins. The B. hermsii outer

ELLEN S. SHANG; JONATHAN T. SKARE; MAURICE M. EXNER; DAVID R. BLANCO; BRUCE L. KAGAN; JAMES N. MILLER; MICHAEL A. LOVETT

217

Tidal Stress on Europa: Sensitivity to Ice Shell Thickness  

NASA Astrophysics Data System (ADS)

On Europa, tidal stress computed with a thin-shell approximation have been used successfully to explain many characteristics of the tectonic features observed (Helfenstein and Parmentier. 1985. Icarus \\textbf{61}.; McEwen. 1986. Icarus \\textbf{321}.; Greenberg et al. 1998. Icarus \\textbf{135}.; Greenberg and Geissler. 2002. Meteoritics and Planetary Science \\textbf{37}.). For example, cycloidal cracks have been reproduced by tracking crack propagation as the diurnally varying tidal stresses exceed the tensile strength of the surface ice (Hoppa et al. 1999. Icarus \\textbf{153}; Sarid et al. 2005. DPS). The thin shell approximation assumes the outer layer is an elastic sheet, decoupled from the deeper interior of the body by a fluid layer. The sheet deforms to fit the tidal figure taken by the body's interior, producing stress on the surface. To compute Europa's tidal deformation with a finite thickness to the outer elastic shell, we treat Europa as an incompressible body with layers homogeneous in density and rigidity (Sabadini and Vermeersen. 2004. Global Dynamics of the Earth). This method predicts the stress on its surface for various assumed internal structures. We find that the stress on Europa's surface is sensitive to the thickness of the icy crust. For a thick ice layer, approaching the thickness of the total H2O layer, the stresses are qualitatively different from thin ice shells, predicting compression along the tidal bulges. These stresses might be similar to the stresses produced on moons with deep subsurface oceans, like Ganymede. Even if the ice is only 10 or 20 km thick, there are substantial differences in the theoretical stresses from those predicted by the traditional thin-sheet method. Using stresses produced by multi-layered models of Europa to understand the tectonic fabric of its surface has the potential to constrain the thickness of Europa's icy crust.

Hurford, T. A.; Greenberg, R.

2005-08-01

218

The detached dust and gas shells around the carbon star U Antliae  

NASA Astrophysics Data System (ADS)

Context. Geometrically thin, detached shells of gas have been found around a handful of carbon stars. The current knowledge on these shells is mostly based on CO radio line data. However, imaging in scattered stellar light adds important new information as well as allows studies of the dust shells. Aims: Previous observations of scattered stellar light in the circumstellar medium around the carbon star U Ant were taken through filters centred on the resonance lines of K and Na. These observations could not separate the scattering by dust and atoms. The aim of this paper is to remedy this situation. Methods: We have obtained polarization data on stellar light scattered in the circumstellar medium around U Ant through filters which contain no strong lines, making it possible to differentiate between the two scattering agents. Kinematic, as well as spatial, information on the gas shells were obtained through high-resolution echelle spectrograph observations of the KI and NaD lines. Results: We confirm the existence of two detached shells around U Ant. The inner shell (at a radius of ?43´´ and a width of ?2´´) consists mainly of gas, while the outer shell (at a radius of ?50´´ and a width of ?7´´) appears to consist exclusively of dust. Both shells appear to have an over-all spherical geometry. The gas shell mass is estimated to be 2 × 10-3~M?, while the mass of the dust shell is estimated to be 5 × 10-5~M?. The derived expansion velocity, from the KI and NaD lines, of the gas shell, 19.5 km s-1, agrees with that obtained from CO radio line data. The inferred shell age is 2700 years. There is structure, e.g. in the form of arcs, inside the gas shell, but it is not clear whether these are due to additional shells. Conclusions: Our results support the hypothesis that the observed geometrically thin, detached shells around carbon stars are the results of brief periods of intense mass loss, probably associated with thermal pulses, and subsequent wind-wind interactions. The separation into a gas and a dust shell, with different widths, is most likely the effect of different dynamical evolutions of the two media after their ejection.

Maercker, M.; Olofsson, H.; Eriksson, K.; Gustafsson, B.; Schöier, F. L.

2010-02-01

219

Thermal coupling between the mantle, outer core and inner core: an experimental model  

NASA Astrophysics Data System (ADS)

Thermal coupling between the mantle and the outer core has been proposed based upon the correlation between the patterns of stationary geomagnetic field and the seismic heterogeneity of the lower mantle (Bloxham and Gubbins, 1987). We have studied how such thermal heterogeneity can affect the outer core flow, using laboratory experiments in a rapidly rotating hemispherical shells (Sumita and Olson, 1999, 2002). Here I review the results obtained from these experiments, and offer their implications to the Earth's core. We use a hemispherical shell with an outer diameter of 30 cm and spin it at 207 rpm to achieve an Ekman number of 4.7 × 10-6. By circulating a cooling water through the inner sphere, we impose a radial temperature gradient, and achieve a Rayleigh number of up to 44 times the critical value. For most Rayleigh numbers (Ra/Rac > 8), thermal convection consists of meandering plumes that originate from inner and outer boundaries and are advected westward by the mean zonal flow (Sumita and Olson, 2000). When we impose a thermal anomaly at the outer boundary using a strip heater we find that the warm fluid generated by the heater flows eastward. When Q\\ast = (Applied total heat flow)/(Total heat flow at ICB) > 0.7, we find that a stationary front forms at the east of the heater which separates the warm eastward flow and cold westward flow. The stationary front take the form of a spiral and extends from the outer boundary towards the inner boundary, along which a jet flows towards the inner boundary. Simple estimate shows that the condition Q\\ast > 1 can be satisified in the Earth's core. Since centrifugal force is used to simulate the radially dependent gravity, a heater in the experiment corresponds to a cold anomaly at the CMB. Seismic tomography suggest that such an anomaly exists beneath east Asia. Our experiments suggest that there is a cold eastward flow in the Pacific and a warm westward flow elsewhere which is consistent with the core flow model obtained from geomagnetic secular variation (Bloxham and Jackson, 1991). Our experiments also suggest that inner core growth rate is fast at the western hemisphere, which coincides with the region of large P-wave anisotropy of the inner core (Tanaka and Hamaguchi, 1997). According to the model of Yoshida et al. (1996), elastic strain energy of deformed crystals, which is the cause for preferred orientation, scales as \\propto (growth rate)2, and thus explains the region of large anisotropy in the western hemisphere. Sumita and Olson, 1999, Science, 286, 1547-1549. ibid, 2002, J.Geophys. Res., 107, 10.1029/2001JB000548.

Sumita, I.

2007-12-01

220

Shell Creek Summers  

NSDL National Science Digital Library

What would motivate high school students to donate valuable summer vacation time to do science research?--the opportunity to make a difference! The Shell Creek Watershed Improvement Group (SCWIG) was formed to identify and promote needed conservation practices within a local watershed, and turned to the high school science department to help educate the public on water quality in the watershed and to establish a monitoring system that would be used to improve surface and groundwater quality. Since 2002, for the past three summers, in this ongoing project, students collect water quality data and report their findings to the three involved community organizations.

Seier, Mark; Goedeken, Suzy

2005-04-01

221

Eikonal Corrections to Hard Processes.  

National Technical Information Service (NTIS)

We consider within Quantum Chromodynamics those semi-inclusive hard processes where two large mass scales appear. Summation of single and double logarithms arising from soft gluonic emission introduces eikonal form factors. We obtain a satisfactory agreem...

G. Bordes A. Nicolaidis

1981-01-01

222

Melting of polydisperse hard disks  

NASA Astrophysics Data System (ADS)

The melting of a polydisperse hard-disk system is investigated by Monte Carlo simulations in the semigrand canonical ensemble. This is done in the context of possible continuous melting by a dislocation-unbinding mechanism, as an extension of the two-dimensional hard-disk melting problem. We find that while there is pronounced fractionation in polydispersity, the apparent density-polydispersity gap does not increase in width, contrary to 3D polydisperse hard spheres. The point where the Young’s modulus is low enough for the dislocation unbinding to occur moves with the apparent melting point, but stays within the density gap, just like for the monodisperse hard-disk system. Additionally, we find that throughout the accessible polydispersity range, the bound dislocation-pair concentration is high enough to affect the dislocation-unbinding melting as predicted by Kosterlitz, Thouless, Halperin, Nelson, and Young.

Pronk, Sander; Frenkel, Daan

2004-06-01

223

Water Hardness and Cardiovascular Disease.  

National Technical Information Service (NTIS)

A brief review of the present state of knowledge regarding the relationship of water hardness to cardiovascular disease. Also included are recommendations for future research and a statement on the appropriateness of modifying current water treatment prac...

1979-01-01

224

THE ORBITS OF THE OUTER URANIAN SATELLITES  

SciTech Connect

We report on the numerically integrated orbits for the nine outer Uranian satellites. The orbits are calculated based on fits to the astrometric observations for the period from 1984 to 2006. The results include the state vectors, post-fit residuals, and mean orbital elements. We also assess the accuracy of the orbital fits and discuss the need for future measurements.

Brozovic, M.; Jacobson, R. A. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States)], E-mail: marina.brozovic@jpl.nasa.gov

2009-04-15

225

A Model Environment for Outer Zone Electrons.  

National Technical Information Service (NTIS)

A brief morphology of outer zone electrons is given to illustrate the nature of the phenomena that we are attempting to model. This is followed by a discussion of the data processing that was done with the various data received from the experimenters befo...

G. W. Singley J. I. Vette

1972-01-01

226

Versatile Langmuir Probe for Outer Planet Missions  

Microsoft Academic Search

This presentation outlines the design of a Versatile Langmuir Probe (VLP), intended to be deployed as a key instrument on the Europa Jupiter Systems Mission (EJSM) and other outer planet missions. The VLP will make in-situ planetary plasma particle, plasma wave, and electric field measurements that will be critical in developing a comprehensive picture of planetary processes. The VLP is

D. Allen; C. S. Fish; F. J. Crary; P. Leung; R. Frampton; C. Swenson; D. C. Thompson; L. Peltz

2009-01-01

227

BIOREACTOR DESIGN - OUTER LOOP LANDFILL, LOUISVILLE, KY  

EPA Science Inventory

Bioreactor field demonstration projects are underway at the Outer Loop Landfill in Louisville, KY, USA. The research effort is a cooperative research effort between US EPA and Waste Management Inc. Two primary kinds of municipal waste bioreactors are under study at this site. ...

228

Depletion of the Outer Asteroid Belt  

NASA Astrophysics Data System (ADS)

The depletion of the outer asteroid belt has been a puzzle for planetary scientists for a long time. Theories based on gravitational perturbations from planets at their current orbits fail to explain the observed structure of the outer belt, particularly between 3.5 and 3.9 astronomical units. However, the orbital configuration of planets today may not represent what it was when asteroids were formed. In the early history of the Solar system, orbital migration of the giant planets has been shown to be quite possible (Fernandez and Ip, 1984, Icarus 58:109-120; Fernandez and Ip, 1996, Planet. Sp. Sci. 44:431-439). This early dynamical history of the outer planets is also supported by a recent theory for the origin of Pluto and the structure of the Kuiper belt (Malhotra 1993, Nature 365:819-821; Malhotra 1995, AJ 110:420-429). We have studied the evolution of asteroids subject to perturbations of the giant planets, and we show that outer belt asteroids are depleted efficiently due to the mean motion resonance sweeping that accompanied the migration of giant planets.

Liou, J. C.; Malhotra, R.

1996-09-01

229

THE RENEWAL OF PHOTORECEPTOR CELL OUTER SEGMENTS  

Microsoft Academic Search

The utilization of methionine-aH by retinal photorcceptor cells has been studied by radio- autographic tcchnique in the rat, mouse, and frog. In all three species, the labeled amino acid is conccntratcd initially in the inner segment of the cell. Within 24 hr, the radioactive material is displaced to the base of the outer segment, where it accumulates as a distinct

RICHARD W. YOUNG

1967-01-01

230

Small Bodies of the Outer Solar System  

Microsoft Academic Search

The population of small bodies of the outer Solar System includes objects of different nature: Jupiter Trojans, Centaurs, trans-Neptunian objects, cometary nuclei and satellites of the giant planets. The analysis of these bodies can give us important hints on the composition of the primordial solar nebula at large heliocentric distances, and on the processes which governed the early phases of

E. Dotto; M. A. Barucci

2004-01-01

231

Future exploration of the outer solar system  

Microsoft Academic Search

Exploration of the outer solar system is constrained by vast distances, consequent communications and light time limitations, power, and long flight times. Early reconnaissance missions (Pioneer 10 and 11, Voyager 1 and 2) employed relatively fast trajectories resulting in very fast fly-bys. The next generation of exploration (Galileo and Cassini) has been characterized by spacecraft with large propellant systems and

T. Johnson

2004-01-01

232

Dust environment in the outer Solar System  

Microsoft Academic Search

Since the discovery of the first Edgeworth-Kuiper Belt (EKB) object in 1992, more than 600 EKB objects have been discovered so far. Collisions among EKB objects could produce a significant amount of dust in the outer Solar System. Due to interactions with the giant planets, the EKB dust disk has non-uniform distributions in both radial and azimuthal directions. Some of

J.-C. Liou

2003-01-01

233

Cratering Rates in the Outer Solar System  

NASA Astrophysics Data System (ADS)

We assess the sizes and numbers of the comets, and discuss impact rates by comets and asteroids on planets and satellites throughout the outer solar system. We do some other stuff too, but you can read about that in the abstract.

Zahnle, K.; Schenk, P.; Dones, L.; Levison, H.

2003-03-01

234

Improved Outer Seal for First Stage Turbine.  

National Technical Information Service (NTIS)

The patent application relates to an outer air seal for the first stage turbine of an engine having the seal segments made of a high strength base material with a highly oxidation-corrosion resistant abradable alloy layer bonded to the surface. Another em...

A. F. Corey

1974-01-01

235

Outer-rotor polysilicon wobble micromotors  

Microsoft Academic Search

This paper reports the development of a new class of polysilicon surface-micromachined wobble micromotors in which the rotor outer radius is exposed for mechanical coupling and the first instance of a polysilicon wobble micromotor directly driving another mechanical component. These motors are fabricated in a three-mask process which results in a flange bearing. The rotor and stator are fabricated from

Keren Deng; Mehran Mehregany

1998-01-01

236

The magnetospheres of the outer planets  

SciTech Connect

Research on the magnetospheres of all of the outer planets including Jupiter, Uranus, Neptune, and Pluto is reviewed for the 1987-1990 time period. Particular attention is given to magnetospheric structure, plasma transport, Jovian aurora, Io and the plasma torus, Titan and its magnetospheric interactions, rings and dusty plasmas, magnetospheric convection, and satellite interactions.

Mcnutt, R.L., Jr. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

237

Nonthermal support for the outer intracluster medium  

NASA Astrophysics Data System (ADS)

We submit that nonthermalized support for the outer intracluster medium in relaxed galaxy clusters is provided by turbulence, which is driven by inflows of intergalactic gas across the virial accretion shocks. We expect this component to increase briskly during the cluster development for z ? 1/2, owing to three factors. First, the accretion rates of gas and dark matter subside when they feed on the outer wings of the initial perturbations in the accelerating Universe. Second, the infall speeds decrease across the progressively shallower gravitational potential at the shock position. Third, the shocks eventually weaken and leave less thermal energy to feed the intracluster entropy, but relatively more bulk energy to drive turbulence into the outskirts. The overall outcome from these factors is physically modeled and analytically computed; thus we ascertain how these concur in setting the equilibrium of the outer intracluster medium, and predict how the observables in X-rays and ?waves are affected, so as to probe the development of outer turbulence over wide cluster samples. By the same token, we quantify the resulting negative bias to be expected in the total mass evaluated from X-ray measurements.

Cavaliere, A.; Lapi, A.; Fusco-Femiano, R.

2011-01-01

238

Meteorites from the Outer Solar System?  

Microsoft Academic Search

We investigate the possibility that a small fraction of meteorites originate from the outer solar system, i.e., from the Kuiper belt, the Oort cloud, or from the Jupiter-family comet reservoir. Dynamical studies and meteor observations show that it is possible for cometary solid fragments to reach Earth with a velocity not unlike that of asteroidal meteorites. Cosmochemical data and orbital

Matthieu Gounelle; Alessandro Morbidelli; P. A. Bland; P. Spurny; E. D. Young; Mark Sephton

2008-01-01

239

Elastic recovery at hardness indentations  

Microsoft Academic Search

The mechanics of hardness indentation are considered. On the basis of a cycle in which the loading is elastic-plastic and the unloading (and subsequent reloading) elastic, an expression is derived for the relative depth recovery of the impression as a function of hardness\\/modulus,H\\/E. Experimental observations on indented surfaces of selected materials, mostly ceramics, using a tilting procedure in the scanning

B. R. Lawn; V. R. Howes

1981-01-01

240

30 CFR 77.1710-1 - Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced...  

Code of Federal Regulations, 2013 CFR

...Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced...Distinctively colored hard hats or hard caps; identification for newly employed, inexperienced miners. Hard hats or hard caps distinctively different in color...

2013-07-01

241

30 CFR 75.1720-1 - Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced...  

Code of Federal Regulations, 2013 CFR

...Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced...Distinctively colored hard hats, or hard caps; identification for newly employed, inexperienced miners. Hard hats or hard caps distinctively different in color...

2013-07-01

242

Tests und Inbetriebnahme der LHCb Outer Tracker Front-end Elektronik und eine Studie zur Abschätzung des Untergrundes im Zerfall $B^{0}_{s} \\\\to J\\\\Psi \\\\Phi$  

Microsoft Academic Search

The readout electronic of the LHCb outer tracker measures the drift time of a straw tube. The front-end electronic consists of three radiation hard chips. The ASDBLR preamplifier amplifies and discriminates the charge puls produced by the drift chamber. The OTIS-TDC chip measures the drift time every 25 ns on 32 detector channels. The generated data is send via an

Jan Knopf; Ulrich Uwer

2009-01-01

243

Analysis of the Outer Continental Shelf Lands Act amendments of 1978  

SciTech Connect

Studies which estimate potential offshore oil and gas resources and recoverable hard minerals were used to justify the Federal leasing provisions of the Outer Continental Shelf Lands Act Amendments of 1978. The amendments are examined in terms of their policy objectives and the leasing problems they address. Internal conflicts among the objectives (e.g., between resource development and environmental protection and between Federal and private participation) have raised criticism. The concession approach is continued, although the world trend is away from Federal policies which take a comprehensive view of energy and resource issues. The amendments also establish funds for oil spill pollution, damages to commerical fishing, and assistance to coastal states. (DCK)

Krueger, R.B. (Nossaman, Krueger and Marsh, Los Angeles, CA); Singer, L.H.

1979-10-01

244

In situ lyophilisation of nifedipine directly in hard gelatine capsules.  

PubMed

Hydrophobic drugs present a challenge due to: (i) adhesion and agglomeration; hence the choice of the suitable processing technique to have the drugs into orally administered dosage forms is critical. (ii) Poor dissolution and poor aqueous solubility; hence poor bioavailability. A novel method which is in situ lyophilisation directly in hard gelatin capsule shells was used in this research to enhance the dissolution of nifedipine (a model hydrophobic drug) in the presence of co-povidone, Pluronic(®)F-127 and inulin as enhancement excipients (to the best of our knowledge those excipients have not been previously used with nifedipine in lyophilised forms). Solutions of nifedipine and excipients in a range of concentrations (0.5, 1, 5 and 10%w/v) were prepared using a co-solvent system of tert- butyl alcohol/water mixture. These solutions were filled directly into bodies of size 000 hard gelatin capsule shells and freeze dried. Pure drug and all formulations were characterised by solubility, wetting studies and in vitro dissolution. Also, conformational integrity and thermal characteristics of nifedipine formulations were investigated using FT-IR spectroscopy and differential scanning calorimetry (DSC), respectively. The in situ lyophilisation of nifedipine with excipients, looks a promising method not only to improve the hydrophobic drug dissolution but also to be cost effective. PMID:22992055

Crum, Matthew; Elkordy, Amal Ali; Zarara, Moataz; Elkordy, Eman Ali

2012-09-20

245

Biomechanics of turtle shells: how whole shells fail in compression.  

PubMed

Turtle shells are a form of armor that provides varying degrees of protection against predation. Although this function of the shell as armor is widely appreciated, the mechanical limits of protection and the modes of failure when subjected to breaking stresses have not been well explored. We studied the mechanical properties of whole shells and of isolated bony tissues and sutures in four species of turtles (Trachemys scripta, Malaclemys terrapin, Chrysemys picta, and Terrapene carolina) using a combination of structural and mechanical tests. Structural properties were evaluated by subjecting whole shells to compressive and point loads in order to quantify maximum load, work to failure, and relative shell deformations. The mechanical properties of bone and sutures from the plastral region of the shell were evaluated using three-point bending experiments. Analysis of whole shell structural properties suggests that small shells undergo relatively greater deformations before failure than do large shells and similar amounts of energy are required to induce failure under both point and compressive loads. Location of failures occurred far more often at sulci than at sutures (representing the margins of the epidermal scutes and the underlying bones, respectively), suggesting that the small grooves in the bone created by the sulci introduce zones of weakness in the shell. Values for bending strength, ultimate bending strain, Young's modulus, and energy absorption, calculated from the three-point bending data, indicate that sutures are relatively weaker than the surrounding bone, but are able to absorb similar amounts of energy due to higher ultimate strain values. PMID:23203474

Magwene, Paul M; Socha, John J

2012-11-30

246

GMI spectra of amorphous wires with different types of magnetic anisotropy in the core and the shell regions  

Microsoft Academic Search

The giant magneto-impedance (GMI) spectra of amorphous wires with low magnetostriction are studied theoretically, based on the model of an amorphous wire consisting of a uniformly magnetized inner core with axial anisotropy and an outer shell where the easy anisotropy axis may be circumferential or radial. It is shown that the presence of the uniformly magnetized core considerably modifies the

N. A Usov; A. S Antonov; A. N Lagar'kov; A. B Granovsky

1999-01-01

247

Application of Shell Model with the Modified Surface delta Interaction to exp 42 Ca and exp 42 Sc Nuclei.  

National Technical Information Service (NTIS)

The shell model with MSDI residual interaction is used to investigate properties of levels in the exp 42 Ca and exp 42 Sc nuclei. The exp 40 Ca core with two active outer nucleons is assumed. The energy matrices are diagonalized and the calculated level s...

A. Jasielska S. Wiktor

1975-01-01

248

Vulnerability of the paper Nautilus (Argonauta nodosa) shell to a climate-change ocean: potential for extinction by dissolution.  

PubMed

Shell calcification in argonauts is unique. Only females of these cephalopods construct the paper nautilus shell, which is used as a brood chamber for developing embryos in the pelagic realm. As one of the thinnest (225 ?m) known adult mollusc shells, and lacking an outer protective periostracum-like cover, this shell may be susceptible to dissolution as the ocean warms and decreases in pH. Vulnerability of the A. nodosa shell was investigated through immersion of shell fragments in multifactorial experiments of control (19 °C/pH 8.1; pCO(2) 419; ?(Ca) = 4.23) and near-future conditions (24 °C/pH 7.8-7.6; pCO(2) 932-1525; ?(Ca) = 2.72-1.55) for 14 days. More extreme pH treatments (pH 7.4-7.2; pCO(2) 2454-3882; ?(Ca) = 1.20-0.67) were used to assess tipping points in shell dissolution. X-ray diffractometry revealed no change in mineralogy between untreated and treated shells. Reduced shell weight due to dissolution was evident in shells incubated at pH 7.8 (projected for 2070) after 14 days at control temperature, with increased dissolution in warmer and lower pH treatments. The greatest dissolution was recorded at 24 °C (projected for local waters by 2100) compared to control temperature across all low-pH treatments. Scanning electron microscopy revealed dissolution and etching of shell mineral in experimental treatments. In the absence of compensatory mineralization, the uncovered female brood chamber will be susceptible to dissolution as ocean pH decreases. Since the shell was a crucial adaptation for the evolution of the argonauts' holopelagic existence, persistence of A. nodosa may be compromised by shell dissolution in an ocean-change world. PMID:23111135

Wolfe, Kennedy; Smith, Abigail M; Trimby, Patrick; Byrne, Maria

2012-10-01

249

The high radial velocity of an outer filament of the Helix nebula (NGC 7293)  

NASA Astrophysics Data System (ADS)

An echele spectrograph was used to obtain a series of long-slit high-resolution line profiles of H-alpha and forbidden N Ii lines from the center of the Helix nebula (NGC 7293) to the filament 11 arcmin east. This filament shows a blue-shifted velocity of about 50 km/s with respect to the nebula mean velocity, i.e. larger than the approximately 25 km/s expansion of the bright helical ring. It is suggested that this feature may be part of a radially expanding ellipsoidal shell whose long axis is inclined towards the line-of-sight. Possible mechanisms for the formation of such a high-velocity feature are discussed. Collision of a hot fast wind and a cold red-giant wind cannot easily account for the presence of multiple shells nor the high radial velocity of the outer filament. A high-mass-loss high-velocity ejection event ('superwind') at the end of the red-giant phase of an AGB star is suggested as a more probable cause or the high-velocity outer structure.

Walsh, J. R.; Meaburn, J.

1987-02-01

250

Poloidal rotation velocities in the outer half of Alcator-C plasmas  

NASA Astrophysics Data System (ADS)

Poloidal rotation velocities in the outer half of ohmically heated Alcator-C plasmas have been determined from the Doppler shift of impurity emission lines. The measurements were made using a high-resolution photon-counting detector, sensitive to wavelengths from ~1200 to ~2000 Å, mounted in the exit plane of a 1-m Ebert-Fastie spectrometer. The following transitions were used: 2s2p1P°1-2p2 1D2 at 1371.292 at 1371.292 Å in O v, 2s 2S1/2-2p2P°1/2 at 1242.804 Å in N v (both of which exist near the limiter radius in Alcator-C), and 1s2s 3S1-1s2p 3°2 at 1623.63 Å in O vii (which exists at r/a~0.8). The measured rotation velocities are 4-5×105 cm/s in the direction of the electron diamagnetic drift at the radius of the O v emission shell and ~6×105 cm/s at the radius of the O vii emission shell, again in the electron diamagnetic drift direction. Therefore poloidal rotation of the outer half of the Alcator-C plasma with a velocity of several times 105 cm/s in the direction of the electron diamagnetic drift is firmly established by these measurements.

Benjamin, R. D.; Terry, J. L.; Moos, H. W.

1990-01-01

251

Development of polyvinyl alcohol shells overcoated with polystyrene layer for inertial confinement fusion experiments  

SciTech Connect

In inertial fusion experiments, the use of polymer shells provides more efficient ablative implosion and significantly reduced radiation preheat compared with the glass shells currently used. We have developed a method of fabricating polyvinyl alcohol (PVA) shells overcoated with a polystyrene (PS) layer. The method utilizes the emulsion technique previously developed by us, and employs three different liquid phases. A 5 wt. % aqueous PVA solution is mixed with a 7 wt. % PS solution in dichloromethane while stirring. The mixture is then poured into a 1 wt. % PS solution in cidhloromethane while stirring. The mixture is then poured into a 1 wt. % aqueous gelatin solution. The resulting emulsion is heated to evaporate the dichloromethane, resulting in solid PS shells encapsulating the PVA solution. The PS shells are subsequently washed and dried in vacuum to drive off the remaining water. As a result, a PVA shell is formed inside an overcoating PS shell which exhibits a good surface quality in the outer diameter and wall thickness regime currently desired by inertial confinement fusion experimenters.

Kubo, U.; Tsubakihara, H.

1987-07-01

252

Shell optimizes beta field completions  

Microsoft Academic Search

Shell California Production Inc., a subsidiary of Shell Oil Co., has developed innovative perforating, washing, and gravel packing techniques to optimize production rates of the Beta field, offshore Long Beach, Calif. Field development is complicated because the heavy oil reservior, which consists of nine separate, unconsolidated sand intervals, lies at a shallow depth, with the gross pay section as thick

1983-01-01

253

Nested shell superconducting magnet designs  

Microsoft Academic Search

A novel concept for manufacturing the toroidal field coil is described. In the nested shell concept, the conductor is layer-wound in grooves in a shell that lies in the toroidal direction. This simplifies substantially the winding process, both in laying down the conductor and in reducing the number of joints in the graded case. An entire row (of the same

L. Bromberg; P. Titus; J. E. C. Williams

1991-01-01

254

Omega-Gate p-MOSFET With Nanowirelike SiGe\\/Si Core\\/Shell Channel  

Microsoft Academic Search

We demonstrated, for the first time, p-MOSFETs (LG ges 40 nm) with SiGe\\/Si core\\/shell channel integrated on bulk Si using a CMOS-compatible top-down processes. The Omega-shaped nanowire (NW)-like channels comprised of ~12-nm-thick inner SiGe core and 4-nm-thick outer Si shell. The devices exhibited good subthreshold characteristics (with SS ~128 mV\\/dec), suggesting successful surface passivation of the SiGe NW body by

Y. Jiang; N. Singh; T. Y. Liow; P. C. Lim; S. Tripathy; G. Q. Lo; D. S. H. Chan; D.-L. Kwong

2009-01-01

255

7 CFR 983.30 - Shelled pistachios.  

Code of Federal Regulations, 2010 CFR

... 2009-01-01 false Shelled pistachios. 983.30 Section 983.30 Agriculture...Nuts), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA Definitions § 983.30 Shelled pistachios. Shelled pistachios means...

2009-01-01

256

7 CFR 983.29 - Shelled pistachios.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture...Nuts), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND... Definitions § 983.29 Shelled pistachios. Shelled pistachios means...

2010-01-01

257

Formaldehyde in the Far Outer Galaxy: Constraining the Outer Boundary of the Galactic Habitable Zone  

Microsoft Academic Search

We present results from an initial survey of the 212111 transition of formaldehyde (H2CO) at 140.8 GHz in giant molecular clouds in the far outer Galaxy (RG 16 kpc). Formaldehyde is a key prebiotic molecule that likely plays an important role in the development of amino acids. Determining the outermost extent of the H2CO distribution can constrain the outer limit

Samantha K. Blair; Loris Magnani; Jan Brand; Jan G. A. Wouterloot

2008-01-01

258

Aqueous synthesis of glutathione-capped CdTe/CdS/ZnS and CdTe/CdSe/ZnS core/shell/shell nanocrystal heterostructures.  

PubMed

Here we demonstrate the aqueous synthesis of colloidal nanocrystal heterostructures consisting of the CdTe core encapsulated by CdS/ZnS or CdSe/ZnS shells using glutathione (GSH), a tripeptide, as the capping ligand. The inner CdTe/CdS and CdTe/CdSe heterostructures have type-I, quasi-type-II, or type-II band offsets depending on the core size and shell thickness, and the outer CdS/ZnS and CdSe/ZnS structures have type-I band offsets. The emission maxima of the assembled heterostructures were found to be dependent on the CdTe core size, with a wider range of spectral tunability observed for the smaller cores. Because of encapsulation effects, the formation of successive shells resulted in a considerable increase in the photoluminescence quantum yield; however, identifying optimal shell thicknesses was required to achieve the maximum quantum yield. Photoluminescence lifetime measurements revealed that the decrease in the quantum yield of thick-shell nanocrystals was caused by a substantial decrease in the radiative rate constant. By tuning the diameter of the core and the thickness of each shell, a broad range of high quantum yield (up to 45%) nanocrystal heterostructures with emission ranging from visible to NIR wavelengths (500-730 nm) were obtained. This versatile route to engineering the optical properties of nanocrystal heterostructures will provide new opportunities for applications in bioimaging and biolabeling. PMID:22551311

Samanta, Anirban; Deng, Zhengtao; Liu, Yan

2012-05-14

259

Site-specific carbon deposition for hierarchically ordered core/shell-structured graphitic carbon with remarkable electrochemical performance.  

PubMed

A fascinating core-shell-structured graphitic carbon material composed of ordered microporous core and uniform mesoporous shell is fabricated for the first time through a site-specific chemical vapor deposition process by using a nanozeolite@mesostructured silica composite molecular sieve as the template. The mesostructure-directing agent cetyltrimethylammonium bromide in the shell of the template can be either burned off or carbonized so that it is successfully utilized as a pore switch to turn the shell of the template "on" or "off" to allow selective carbon deposition. The preferred carbon deposition process can be performed only in the inner microporous zeolite cores or just within the outer mesoporous shells, resulting in a zeolite-like ordered microporous carbon or a hollow mesoporous carbon. Full carbon deposition in the template leads to the new core-shell-structured microporous@mesoporous carbon with a nanographene-constructed framework for fast electron transport, a microporous nanocore with large surface area for high-capacity storage of lithium ions, a mesoporous shell with highly opened mesopores as a transport layer for lithium ions and electron channels to access inner cores. The ordered micropores are protected by the mesoporous shell, avoiding pore blockage as the formation of solid electrolyte interphase layers. Such a unique core-shell-structured microporous@mesoporous carbon material represents a newly established lithium ion storage model, demonstrating high reversible energy storage, excellent rate capability, and long cyclic stability. PMID:24039038

Lv, Yingying; Wu, Zhangxiong; Qian, Xufang; Fang, Yin; Feng, Dan; Xia, Yongyao; Tu, Bo; Zhao, Dongyuan

2013-09-13

260

NICMOS Study of Nova Shells  

NASA Astrophysics Data System (ADS)

We propose to obtain multi-wavelength infrared images of the old nova shells of QU Vul, QV Vul, V1974 Cyg, and V723 Cas. The angular expansion rates and spatial distribution of the ejecta in both the continuum and emission lines of ionized gas will be determined. The objectives of our observations are to utilize HST's unique angular resolution and wavelength coverage to compare current observations of the shell of these unique novae with the angular expansion rates predicted from radio, optical, and infrared measurements made in the early phases of their eruption, and to determine the ionization and density structure of the clumpy ejecta. From the flux of the free-free continuum emission shell masses will be derived. The proposed HST NICMOS observations offer the unique possibility to significantly improve our knowledge of basic physical parameters such as luminosity and shell mass and the structure of nova shells.

Krautter, Joachim

1997-12-01

261

Helical shell models for MHD  

NASA Astrophysics Data System (ADS)

A shell model for magnetohydrodynamics (MHD) is derived directly from the dynamical system driving the evolution of three helical modes interacting in a triad. The use of helical modes implies that two shell variables are required for the velocity as well as for the magnetic field. The advantage of the method is the automatic conservation of all the ideal quadratic MHD invariants. The number of coupling constants is however larger than in traditional shell models. This difficulty is worked around by introducing an averaging procedure that allows to derive the shell model coupling constants directly from the MHD equations. The resulting shell model is used to explore the influence of a helical forcing on the global properties of MHD turbulence close to the onset of the dynamo regime.

Lessinnes, T.; Plunian, F.; Carati, D.

2009-11-01

262

Outer crust of nonaccreting cold neutron stars  

NASA Astrophysics Data System (ADS)

The properties of the outer crust of nonaccreting cold neutron stars are studied by using modern nuclear data and theoretical mass tables, updating in particular the classic work of Baym, Pethick, and Sutherland. Experimental data from the atomic mass table from Audi, Wapstra, and Thibault of 2003 are used and a thorough comparison of many modern theoretical nuclear models, both relativistic and nonrelativistic, is performed for the first time. In addition, the influences of pairing and deformation are investigated. State-of-the-art theoretical nuclear mass tables are compared to check their differences concerning the neutron drip line, magic neutron numbers, the equation of state, and the sequence of neutron-rich nuclei up to the drip line in the outer crust of nonaccreting cold neutron stars.

Rüster, Stefan B.; Hempel, Matthias; Schaffner-Bielich, Jürgen

2006-03-01

263

Outer zone energetic electron spectral measurements  

Microsoft Academic Search

Detailed spectral measurements of energetic electrons between 47-5100 keV have been made with the SC-3 experiment aboard the P78-2 (SCATHA) spacecraft. During the period 29 January-2 February 1979 the spacecraft was in a highly elliptical orbit. Measurements of the outer radiation belt electrons over a range of the closed interval between 3.5 and 8.0 were made near the geomagnetic equator

J. B. Reagan; R. W. Nightingale; E. E. Gaines; W. L. Imhof; E. G. Stassinopoulos

1980-01-01

264

Strongly Contracting Geodesics in Outer Space  

Microsoft Academic Search

We study the Lipschitz metric on Outer Space and prove that fully irreducible elements of Out(F_n) act by hyperbolic isometries with axes which are strongly contracting. As a corollary, we prove that the axes of fully irreducible automorphisms in the Cayley graph of Out(F_n) are stable, meaning that a quasi-geodesic with endpoints on the axis stays within a bounded distance

Yael Algom-Kfir

2008-01-01

265

Planetary protection guidelines for outer planet missions.  

PubMed

Facilities, techniques, and operational procedures used to implement Planetary Protection (PP) requirements for the Viking Project are reviewed in order to better define the COSPAR resolution which proposes that Outer Planet spacecraft be assembled using Viking-like clean room technology. It is concluded that, for such missions, PP requirements can be met by adopting Viking clean room standards, personnel and operation procedures, and by establishing PP as an official entity in project management. PMID:11965661

Stabekis, P; DeVincenzi, D L

1978-01-01

266

Photometric properties of outer planetary satellites  

Microsoft Academic Search

Optical broadband photometry for the satellites J6, J7, J8, S7, S9, U3, U4, and N1 and polarimetry for J6, obtained between 1970 and 1979, are presented. The outer Jovian satellites resemble C-type asteroids; J6 has a rotational lightcurve with a period of approximately 9.5 hr. The satellites beyond Jupiter also show C-like colors with the exception of S7 Hyperion. S9

J. Degewij; B. Zellner; L. E. Andersson

1980-01-01

267

Cosmic ray gradients in the outer heliosphere  

NASA Astrophysics Data System (ADS)

Launched in 1972 and 1973 respectively, the Pioneer 10 and 11 spacecraft are now probing the outer heliosphere on their final escape from the sun. The data in this paper extend for almost an entire solar cycle from launch to early 1983, when Pioneer 10 was at a heliocentric distance of 29 AU and Pioneer 11, 13 AU. The UCSD instruments on board were used to study the gradient, and to look at the time and spatial variations of the cosmic ray intensities.

Walker, F.; Wake, B.; Ip, W.-H.; Axford, I.

1983-08-01

268

K-Shell Vacancy Production and Sharing in (0.2-1.75) MEV/u Fe, co + cr Collisions  

NASA Astrophysics Data System (ADS)

K-shell ionization cross sections and mean vacancy sharing probabilities measured in the near-symmetric collision systems Fe and Co + Cr at 0.2 -1.75 MeV/u energies are reported. The cross section values have been corrected for multiple ionization in the outer (L, M) shells by using the energy and yield shift method. Mean ionization probabilities per electron in the outer shells have been estimated. Calculations in the Briggs model, using SCA with relativistic hydrogenic wave functions and binding correction, could explain the 2p? -molecular orbital ionization cross sections at higher energies (?1 MeV/u). The vacancy sharing results show that predictions of a two-state coupling Meyerhof-Demkov model is less fulfilled at higher energies (?1.5 MeV/u). Note from Publisher: This article contains the abstract and references only.

Ciortea, C.; Piticu, I.; Fluera?u, D.; Dumitriu, D. E.; Enulescu, A.; Gugiu, M. M.; Radu, A. T.

2004-09-01

269

Causes and consequences of outer core stratification  

NASA Astrophysics Data System (ADS)

The Earth's outer core appears to be compositionally layered. Exotic mechanisms such as an original chemically layered core preserved from the Earth's accretionary period, or compositionally different core material delivered by a Moon-creating impactor are conceivable, but require a core whose outermost part has been stratified throughout core history, relying on unknowable processes to achieve. Barodiffusion and core-mantle reaction lead to layers significantly thinner than observed. We show that a balance of mass transferred from the inner core to the top of the outer core is possible, and that the stratification could arise as a byproduct of light element accumulation. However, if a subadiabatic thermal gradient at the top of the outer core exists that quells radial flow, it could serve as a witness of light element accumulation by preventing mixing with the convecting part of the core. The temperature difference through a subadiabatic layer could be 80-300 K and carry heat fluxes through the core-mantle boundary of 0.5-23 TW, given uncertainty in core properties.

Helffrich, George; Kaneshima, Satoshi

2013-10-01

270

Involute, minimal, outer, and increasingly trapped spheres  

SciTech Connect

Seven different refinements of trapped surfaces are proposed, each intended as potential stability conditions. This article concerns spherical symmetry, but each condition can be generalized. Involute trapped spheres satisfy a similar condition to minimal trapped spheres, which are strictly minimal with respect to the Kodama vector. There is also a weaker version of involute trapped spheres. Outer trapped spheres have positive surface gravity. Increasingly (future, respectively, past) trapped spheres generate spheres which are more trapped in a (future, respectively, past) causal direction, with three types: in any such causal direction, along the dual Kodama vector, and in some such causal direction. Assuming the null energy condition, the seven conditions form a strict hierarchy, in the above order. In static space-times, they reduce to three inequivalent definitions, namely, minimal, outer, and increasingly trapped spheres. For a widely considered class of so-called nice (or nondirty) black holes, minimal trapped and outer trapped become equivalent. Reissner-Nordstroem black holes provide examples of this, and that the increasingly trapped differs. Examples where all three refinements differ are provided by a simple family of dirty black holes parametrized by mass and singularity area.

Hayward, Sean A. [Center for Astrophysics, Shanghai Normal University, 100 Guilin Road, Shanghai 200234 (China)

2010-01-15

271

11. VIEW LOOKING EAST, TRACK REMNANTS, OUTER BULKHEAD REMNANT, AND ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

11. VIEW LOOKING EAST, TRACK REMNANTS, OUTER BULKHEAD REMNANT, AND OUTER END OF BRICK ELEVATOR WALL REMAINS, EXTENSION PIER IN BACKGROUND - West Shore Railroad, Pier 7 Grain Elevator, Hudson River & Pershing Road vicinity, West New York, Hudson County, NJ

272

Mineral Resource Management of the Outer Continental Shelf.  

National Technical Information Service (NTIS)

The discussion of the management of the mineral resources of the Outer Continental Shelf leads to the following conclusions: The oil and gas production from the Outer Continental Shelf represents an increasing percentage of the total United States product...

A. E. LaPointe C. B. John M. V. Adams R. F. Kelley R. W. Meurer

1976-01-01

273

Outer Measure, Borel Sets and Lebesgue Measure in the Plane.  

National Technical Information Service (NTIS)

The essential properties of general Lebesque outer measure are discussed. The complete measure space, consisting of the general Lebesque outer measure restricted to the measurable sets, is developed and this measure is shown to be unique. Two characteriza...

D. M. Heming

1970-01-01

274

Benefits of Nuclear Electric Propulsion for Outer Planet Exploration.  

National Technical Information Service (NTIS)

Nuclear electric propulsion (NEP) offers significant benefits to missions for outer planet exploration. Reaching outer planet destinations, especially beyond Jupiter, is a struggle against time and distance. For relatively near missions, such as a Europa ...

L. Kos L. Johnson J. Jones A. Trausch B. Eberle G. Woodcock

2002-01-01

275

Indentation hardness evaluation of cathodic arc deposited thin hard coatings  

Microsoft Academic Search

One trend in the development of wear-resistant vapour deposited coatings is to make them increasingly harder and thinner, by improvement and optimisation of the deposition processes. A complex interdependence exists between the individual properties of a coating and a substrate on the one hand, and those of the ‘composite’ coated system on the other. For example, system stiffness and hardness

J. R. Tuck; A. M. Korsunsky; D. G. Bhat; S. J. Bulla

2001-01-01

276

Magnetic levitation for hard superconductors  

SciTech Connect

An approach for calculating the interaction between a hard superconductor and a permanent magnet in the field-cooled case is proposed. The exact solutions were obtained for the point magnetic dipole over a flat ideally hard superconductor. We have shown that such an approach is adaptable to a wide practical range of melt-textured high-temperature superconductors{close_quote} systems with magnetic levitation. In this case, the energy losses can be calculated from the alternating magnetic field distribution on the superconducting sample surface. {copyright} {ital 1998 American Institute of Physics.}

Kordyuk, A.A. [Institute of Metal Physics, 252680 Kiev 142 (Ukraine)

1998-01-01

277

Future hard disk drive systems  

NASA Astrophysics Data System (ADS)

This paper briefly reviews the evolution of today's hard disk drive with the additional intention of orienting the reader to the overall mechanical and electrical architecture. The modern hard disk drive is a miracle of storage capacity and function together with remarkable economy of design. This paper presents a personal view of future customer requirements and the anticipated design evolution of the components. There are critical decisions and great challenges ahead for the key technologies of heads, media, head-disk interface, mechanics, and electronics.

Wood, Roger

2009-03-01

278

Mobile hard substrata - An additional biodiversity source in a high latitude shallow subtidal system  

NASA Astrophysics Data System (ADS)

This study demonstrates the importance of a hard mobile substratum (hermit crab shells) for Arctic biodiversity. Based on previous observations from other geographic regions we hypothesized that this niche at high latitudes would support a higher biodiversity of epifauna than might be predicted from similar substrata. We test whether the hermit crab epifauna is specific to that substratum providing unique biodiversity components to the local community. From four study sites in Isfjorden (78°N), West Spitsbergen and two study sites in Northern Norway (69°N) we collected approximately 50 each of hermit crabs, gastropods and pebbles, of visually similar surface area using SCUBA diving. Hermit crab shells were colonized by a larger number of epifaunal species than either gastropods or pebbles, even when they were of a larger size. Among 87 taxa found on all the three substrata, 22 occurred only on hermit crab shells. Except for two study sites hermit crab shells also supported more individuals. This study shows that the contribution of shells carried by hermit crabs to high-latitude, shallow-subtidal diversity is higher than might be predicted by their surface area alone and that hermit crabs modify, maintain and create a unique habitat. This is the result of a number of factors interacting positively on the presence of epifauna including shell surface heterogeneity and the complex influence of the crab host.

Balazy, Piotr; Kuklinski, Piotr

2013-03-01

279

Fabrication of core–shell microcapsules using PLGA and alginate for dual growth factor delivery system  

Microsoft Academic Search

To effectively harness the great potential of stem cells, we designed a dual growth factor delivery system for the application toward stem cell differentiation into specific lineages. This system carries a core–shell structure within microcapsules made of poly(l-lactide-co-glycolide) (PLGA) and alginate, which were fabricated using a coaxial electro-dropping method. Both PLGA and alginate were supplied from the inner and outer

Dong Hoon Choi; Chul Ho Park; Ik Hwan Kim; Heung Jae Chun; Dong Keun Han

2010-01-01

280

Utilization of the coconut shell of babaçu ( Orbignya sp.) to produce cement-bonded particleboard  

Microsoft Academic Search

This experiment evaluated the use of the material of the outer coconut shell of babaçu (Orbignya sp.), a palm tree from Brazil, for the manufacture of particleboards bonded with Portland cement. Four treatments were analyzed at two target densities (1.2 g\\/cm3 and 1.4 g\\/cm3) and two levels (0% and 4%) of addition of calcium chloride. The lignocellulosic material from babaçu

Renato Rocha Almeida; Cláudio Henrique Soares Del Menezzi; Divino Eterno Teixeira

2002-01-01

281

Electrospinning of artemisinin-loaded core-shell fibers for inhibiting drug re-crystallization.  

PubMed

The main aim of this study was to inhibit the re-crystallization of a potent antimalarial drug, artemisinin (ART), by encapsulating it in core-shell fibers via a coaxially electrospun method. The ART-infiltrated cellulose acetate (CA) solution as the core material and poly(vinyl pyrrolidone) (PVP) solution as the shell material were used to prepared ART-loaded core-shell fibers ([ART/CA]/PVP). Transmission electron microscopy images confirmed the core-shell structures of the coaxially electrospun fibers. The scanning electron microscope (SEM), X-ray diffraction, and differential scanning calorimetry were performed to characterize the physical states of ART in the fibers. It was observed that ART crystals were formed in the ART-loaded CA/PVP composite fibers (ART/CA/PVP) during the electrospinning process and increased during storage duration. While ART crystals hardly were observed in the fresh core-shell [ART/CA]/PVP fibers with high ART entrapped amount (20 wt.%) and a little was detected after 6-month storage. Fourier transform infrared spectroscopy (FTIR) results illustrated the hydrogen bonding interaction between ART and CA in the core-shell [ART/CA]/PVP fibers mainly contributed to the amorphous state of ART. Importantly, combination of the hydrophilic PVP shell and the amorphous ART in CA core, the core-shell [ART/CA]/PVP fibers provided a continued and stable ART release manner. Ex vivo permeation studies suggested the amorphous ART in the medicated core-shell fibers could permeate through the stratum corneum smoothly. Hence, the core-shell [ART/CA]/PVP fiber matrix could provide a potential application in transdermal patches. PMID:23565867

Shi, Yongli; Zhang, Jianhua; Xu, Shuxin; Dong, Anjie

2012-08-13

282

27 CFR 9.207 - Outer Coastal Plain.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Outer Coastal Plain. 9.207 Section 9.207 Alcohol...Viticultural Areas § 9.207 Outer Coastal Plain. (a) Name. The name of the viticultural...described in this section is âOuter Coastal Plainâ. For purposes of part 4 of this...

2013-04-01

283

Peaceful Use of Outer Space: principles of Japanese Policies on Utilization and Activities in Outer space  

NASA Astrophysics Data System (ADS)

" P e aceful use of outer space of outer space.....Principles of exploitation of outer space was passed in the Japanese Diet. It clearly mentioned that any activity of launching space object into outer space and developing launching rocket should be exclusively for peaceful purpose. NASDA was also established based upon the same principles of the public law. Japanese interpretation of Space Treaty and other related international agreements has been more strict on peaceful use of outer space, like non-military use rather than non-aggressive, because of influence of Japanese Constitution. Treaty and other agreements is analyzed through rapid development of its space activities, technologies and international cooperation with other space powers. Through more than thirty years experiences in space activities in public and private sectors, Japanese domestic laws and policies have not been changed in relation with basic principles. and laws relating to space activities in order to develop new space law and more international cooperation for space utilization rather than military use in new century.

Kosuge, Toshio

2002-01-01

284

Distant HII Regions in the Outer and Outer Scutum Centaurus Arms  

NASA Astrophysics Data System (ADS)

Galactic HII regions are the formation sites of massive OB stars and, as such, are the archetypical tracers of Galactic spiral structure. They are the brightest objects in the Galaxy at radio an infrared wavelengths and can be located across the entire Galactic disk. Therefore, we argue that HII regions are the best indicators of ongoing massive star formation in the outer Galactic disk. Here, I will discuss our efforts to identify distant HII regions using mid-infrared data from WISE or Spitzer, and to follow up with radio recombination line spectroscopic measurements with the Green Bank Telescope. In the first Galactic quadrant, we have found over 30 HII regions in the Outer Arm, and two in the Outer Scutum-Centaurus arm. Prior to our work almost nothing was known about massive star formation in this part of the Galaxy. The Outer Scutum-Centaurus arm detections are the most distant known Galactic HII regions, up to 24 kpc from he Sun and 17 kpc from the Galactic center. In the second and third Galactic quadrants, we have measured the recombination line emission from ~150 newly idenfified HII regions. We will discuss star formation rates and efficiencies in the outer Galactic disk, as well as the completeness of our census of massive star formation.

Anderson, Loren D.; Bania, T. M.; Balser, D. S.; Wenger, T.

2013-06-01

285

Formaldehyde in the far outer galaxy: constraining the outer boundary of the galactic habitable zone.  

PubMed

We present results from an initial survey of the 2(12)-1(11) transition of formaldehyde (H2CO) at 140.8 GHz in giant molecular clouds in the far outer Galaxy (RG >or= 16 kpc). Formaldehyde is a key prebiotic molecule that likely plays an important role in the development of amino acids. Determining the outermost extent of the H2CO distribution can constrain the outer limit of the Galactic Habitable Zone, the region where conditions for the formation of life are thought to be most favorable. We surveyed 69 molecular clouds in the outer Galaxy, ranging from 12 to 23.5 kpc in galactocentric radius. Formaldehyde emission at 140.8 GHz was detected in 65% of the clouds. The H2CO spectral line was detected in 26 of the clouds with RG > 16 kpc (detection rate of 59%), including 6 clouds with RG > 20 kpc (detection rate of 55%). Formaldehyde is readily found in the far outer Galaxy-even beyond the edge of the old stellar disk. Determining the relatively widespread distribution of H2CO in the far outer Galaxy is a first step in establishing how favorable an environment this vast region of the Galaxy may be toward the formation of life. PMID:18266563

Blair, Samantha K; Magnani, Loris; Brand, Jan; Wouterloot, Jan G A

2008-02-01

286

Au34-: A Fluxional Core-Shell Cluster  

SciTech Connect

Among the large Aun – clusters for n > 20, the photoelectron spectra of Au34 – exhibit the largest energy gap (0.94 eV) with well-resolved spectral features, making it a good candidate for structural consideration in conjunction with theoretical studies. Extensive structural searches at several levels of theory revealed that the low-lying isomers of Au34 – can be characterized as fluxional core-shell type structures with 4 or 3 inner atoms and 30 or 31 outer atoms, i.e., Au4@Au30 – and Au3@Au31 –, respectively. Detailed comparisons between theoretical and photoelectron results suggest that the most probable ground state structures of Au34 – are of the Au4@Au30 – type. The 30 outer atoms seem to be disordered or fluxional, giving rise to a number of low-lying isomers with very close energies and simulated photoelectron spectra. The fluxional nature of the outer layer in large gold clusters or nanoparticles may have important implications for their remarkable catalytic activities.

Gu, Xiao; Bulusu, Satya; Li, Xi; Zeng, Xiao Cheng; Li, Jun; Gong, Xingao G.; Wang, Lai S.

2007-06-14

287

Jastrow wave function for condensed phases of Bose particles: Hard-sphere system  

Microsoft Academic Search

By a Monte Carlo variational calculation, it is shown that the description of the ground-state properties of a hard-sphere Bose system is improved if the Jastrow wave function contains a correlation structure at distances intermediate between the first and the second shell of neighbors. We relate these correlations to the zero-point motion of rotons. We predict that the oscillations of

C. de Michelis; G. Masserini; L. Reatto

1978-01-01

288

Shell`s new business segment sparks pipeline construction  

SciTech Connect

Shell Oil Co., the largest producer in the Gulf of Mexico is taking the next step to market its expertise and infrastructure with a new organization called Shell Midstream Enterprises (SME). SME`s primary customers will be Gulf of Mexico and Gulf Coast producers who can tie in to Shell`s infrastructure rather than building their own. And, the company has planned for the growth of this new business by building additional capacity into its systems to meet industry needs. This includes, among other things, production handling on offshore platforms, oil and gas gathering and transportation, natural gas processing and fractionation, natural gas liquids supply and transportation, crude oil trading, telecommunications and property transaction capabilities. The pipeline segment is of course a big piece of that. Shell`s existing pipeline assets associated with the new business include: Seven natural gas gathering systems which include about 65 miles of pipe that currently transport 230 MMcf/d of natural gas through these systems, and more than 1,000 miles of off-shore related crude oil pipelines with capacity of about 1 million barrels daily. This paper discusses these facilities.

Tubb, M.

1996-08-01

289

K-shell and L-shell plasma spectroscopy experiments  

SciTech Connect

Detailed atomic level populations in high temperature and dense plasmas have become increasingly important in laser generated plasmas. Certain spectral line intensity ratios are density-dependent while others are temperature-dependent. Both can be used to extract information concerning population kinetics and ion level populations. In order to be useful these dependencies must be characterized by independent means. In laser produced plasmas this can be done via holographic interferometry for electron density determinations and via the slope of the H-like free-bound continuum of K-shell lines for electron temperature determinations. The characterization of density- and temperature-dependent L-shell lines can be accomplished in ionization balance experiments in which laser irradiance is varied on targets which contain both K-shell and L-shell emitters. The K-shell free-bound continua provide the local temperature determination while holographic interferometry yields density profile information, from which the temperature and density dependent L-shell lines can be characterized. This paper discusses these concepts.

Charatis, G. (KMS Fusion, Inc., Ann Arbor, MI (USA))

1990-10-01

290

Super-Hard X-Ray Emission from ? Carinae Observed with Suzaku  

NASA Astrophysics Data System (ADS)

We present the Suzaku results of ? Carinae in the 5-50keV range conducted twice around the apastron in 2005 August for 50ks and in 2006 February for 20ks. The X-ray Imaging Spectrometer (XIS) produced hard (5-12keV) band spectra, resolving K shell lines from highly ionized Fe and Ni. The Hard X-ray Detector yielded a significant detection in the super-hard (15-50keV) band, which was uncontaminated by near-by sources. We constrained the temperature of the optically thin thermal plasma emission dominant in the hard band to be 3-4keV using the K-shell line features with the XIS. We found significant excess emission above the thermal emission in the super-hard band with the PIN, confirming the previous INTEGRAL ISGRI report. The entire 5-50keV spectra were fitted by a combination of a thermal plasma model plus a flat power-law, or a very hot thermal bremsstrahlung model for the excess emission. No significant change of the excess emission was found at different epochs within the systematic and statistical uncertainties, and no flare-like flux amplification was seen in the hard band, indicating that the excess emission is a steady phenomenon. We argue that the super-hard emission is attributable to the inverse Compton of stellar UV photons by non-thermal electrons or to the thermal bremsstrahlung of very hot plasma, and not to the bremsstrahlung by non-thermal electrons colliding with cold ambient matter.

Sekiguchi, Akiko; Tsujimoto, Masahiro; Kitamoto, Shunji; Ishida, Manabu; Hamaguchi, Kenji; Mori, Hideyuki; Tsuboi, Yohko

2009-08-01

291

A hard case for modeling  

Microsoft Academic Search

What happens to a human head when it is hit in an accident or by a weapon, or subjected to the violence of an emergency ejection from a combat plane? This question is something that interests QinetiQ, part of the former UK Defence Evaluation and Research Agency (DERA). Controlled experimentation on live subjects is hardly an option, but computer modeling

George Marsh

2002-01-01

292

Hard Probes 2012: Experimental Summary  

NASA Astrophysics Data System (ADS)

The 5thinternational Conference on Hard and Electromagnetic Probes in High-Energy Nuclear Collisions was held in May 2012 in Cagliari, Italy. This contribution summarises some of the experimental highlights presented at the meeting, concentrating on new results from LHC and RHIC on parton energy loss ('jet-quenching') and heavy quark meson production ('quarkonia suppression').

Schukraft, J.

2013-08-01

293

Hard scattering in ?p interactions  

NASA Astrophysics Data System (ADS)

We report on the investigation of the final state in interactions of quasi-real photons with protons. The data were taken with the H1 detector at the HERA ep collider. Evidence for hard interactions is seen in both single particle spectra and jet formation. The data can best be described by inclusion of resolved photon processess as predicted by QCD.

Ahmed, T.; Andreev, V.; Andrieu, B.; Arpagaus, M.; Babayev, A.; Bärwolff, H.; Ban, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bassler, U.; Beck, G. A.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bergstein, H.; Bernardi, G.; Bernet, R.; Berthon, U.; Bertrand-Coremans, G.; Besancon, M.; Biddulph, P.; Binder, E.; Bizot, J. C.; Blobel, V.; Borras, K.; Bosetti, P. C.; Boudry, V.; Bourdarios, C.; Brasse, F.; Braun, U.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Burke, S.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Clarke, D.; Clegg, A. B.; Colombo, M.; Coughlan, J. A.; Courau, A.; Coutures, C.; Cozzika, G.; Criegee, L.; Cvach, J.; Dainton, J. B.; Danilov, M.; Dann, A. W. E.; Dau, W. D.; David, M.; Deffur, E.; Delcourt, B.; Delbuono, L.; Devel, M.; Deroeck, A.; Dingus, P.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Drescher, A.; Duboc, J.; Düllmann, D.; Dünger, O.; Duhm, H.; Eberle, M.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellis, N. N.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Evrard, E.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Feng, Y.; Fensome, I. F.; Ference, J.; Ferrarotto, F.; Flauger, W.; Fleischer, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formanek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Fuhrmann, P.; Gabathuler, E.; Gamerdinger, K.; Garvey, J.; Gayler, J.; Gellrich, A.; Gennis, M.; Gensch, U.; Genzel, H.; Gerhards, R.; Gillespie, D.; Godfrey, L.; Goerlach, U.; Goerlich, L.; Goldberg, M.; Goodall, A. M.; Gorelov, I.; Goritchev, P.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Greif, H.; Grindhammer, G.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Handschuh, D.; Hanlon, E. M.; Hapke, M.; Harjes, J.; Hartz, P.; Haydar, R.; Haynes, W. J.; Heatherington, J.; Hedberg, V.; Hedgecock, R.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herma, R.; Herynek, I.; Hildesheim, W.; Hill, P.; Hilton, C. D.; Hladky, J.; Hoeger, K. C.; Huet, Ph.; Hufnagel, H.; Huot, N.; Ibbotson, M.; Jabiol, M. A.; Jacholkowska, A.; Jacobson, C.; Jaffre, M.; Jönsson, L.; Johannsen, K.; Johnson, D.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kasarian, S.; Kaschowitz, R.; Kasselmann, P.; Kathage, U.; Kaufmann, H. H.; Kenyon, I. R.; Kermiche, S.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Köhler, T.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Krüger, U.; Kubenka, J. P.; Küster, H.; Kuhlen, M.; Kurca, T.; Kurzhöfer, J.; Kuznik, B.; Lander, R.; Landon, M. P. J.; Langkau, R.; Lanius, P.; Laporte, J. F.; Lebedev, A.; Lenhardt, U.; Leuschner, A.; Leverenz, C.; Levin, D.; Levonian, S.; Ley, Ch.; Lindström, G.; Loch, P.; Lohmander, H.; Lopez, G. C.; Lüers, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Masson, S.; Mavroidis, A.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Merz, T.; Meyer, C. A.; Meyer, H.; Meyer, J.; Mikocki, S.; Milone, V.; Monnier, E.; Moreau, F.; Moreels, J.; Morris, J. V.; Morton, J. M.; Müller, K.; Murin, P.; Murray, S. A.; Nagovizin, V.; Naroska, B.; Naumann, Th.; Newton, D.; Nguyen, H. K.; Niebergall, F.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Orenstein, S.; Ould-Saada, F.; Pascaud, C.; Patel, G. D.; Peppel, E.; Peters, S.; Phillips, H. T.; Phillips, J. P.; Pichler, Ch.; Pilgram, W.; Pitzl, D.; Prosi, R.; Raupach, F.; Rauschnabel, K.; Reimer, P.; Ribarics, P.; Riech, V.; Riedlberger, J.; Rietz, M.; Robertson, S. M.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Royon, C.; Rudowicz, M.; Ruffer, M.; Rusakov, S.; Rybicki, K.; Ryseck, E.; Sacton, J.; Sahlmann, N.; Sanchez, E.; Sankey, D. P.; Savitsky, M.; Schacht, P.; Schleper, P.; von Schlippe, W.; Schmidt, C.; Schmidt, D.; Schmitz, W.; Schröder, V.; Schulz, M.; Schwind, A.; Scobel, W.; Seehausen, U.; Sell, R.; Seman, M.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shooshtari, H.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Smirnov, P.; Smith, J. R.; Smolik, L.; Soloviev, Y.; Spitzer, H.; Staroba, P.; Steenbock, M.; Steffen, P.; Steinberg, R.; Steiner, H.; Stella, B.; Stephens, K.; Strachota, J.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Taylor, R. E.; Thompson, G.; Thompson, R. J.; Tichomirov, I.; Trenkel, C.; Truöl, P.; Tchernyshov, V.; Turnau, J.; Tutas, J.; Urban, L.; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Vanesch, P.; Vartapetian, A.; Vasdik, J.; Vecko, M.; Verrecchia, P.; Vick, R.; Villet, G.; Vogel, E.; Wacker, K.; Walker, I. W.; Walther, A.; Weber, G.; Wegener, D.; Wegner, A.

1992-12-01

294

Development of radiation hard scintillators.  

National Technical Information Service (NTIS)

Substantial improvements have been made in the radiation hardness of plastic scintillators. Cylinders of scintillating materials 2.2 cm in diameter and 1 cm thick have been exposed to 10 Mrads of gamma rays at a dose rate of 1 Mrad/h in a nitrogen atmosph...

A. Pla-Dalmau D. Woods F. Markley G. Foster R. Blackburn

1992-01-01

295

Infinite Hard-Sphere System.  

National Technical Information Service (NTIS)

The time-evolution for the system of infinitely many particles in space interacting by a hard-sphere potential is constructed. Examples abound of configurations of the infinite system having more than one solution to the Newtonian equations of motion. A r...

R. K. Alexander

1975-01-01

296

Fatigue of biomaterials: Hard tissues  

Microsoft Academic Search

The fatigue and fracture behavior of hard tissues are topics of considerable interest today. This special group of organic materials comprises the mineralized (roughly 50% mineral by volume or greater) and load-bearing tissues of the human body; it includes bone, cementum, dentin and enamel. An understanding of their fatigue behavior and the influence of loading conditions and physiological factors (e.g.

D. Arola; D. Bajaj; J. Ivancik; H. Majd; D. Zhang

2010-01-01

297

HR Del Remnant Anatomy Using Two-Dimensional Spectral Data and Three-Dimensional Photoionization Shell Models  

NASA Astrophysics Data System (ADS)

The HR Del nova remnant was observed with the IFU-GMOS at Gemini North. The spatially resolved spectral data cube was used in the kinematic, morphological, and abundance analysis of the ejecta. The line maps show a very clumpy shell with two main symmetric structures. The first one is the outer part of the shell seen in H?, which forms two rings projected in the sky plane. These ring structures correspond to a closed hourglass shape, first proposed by Harman & O'Brien. The equatorial emission enhancement is caused by the superimposed hourglass structures in the line of sight. The second structure seen only in the [O III] and [N II] maps is located along the polar directions inside the hourglass structure. Abundance gradients between the polar caps and equatorial region were not found. However, the outer part of the shell seems to be less abundant in oxygen and nitrogen than the inner regions. Detailed 2.5-dimensional photoionization modeling of the three-dimensional shell was performed using the mass distribution inferred from the observations and the presence of mass clumps. The resulting model grids are used to constrain the physical properties of the shell as well as the central ionizing source. A sequence of three-dimensional clumpy models including a disk-shaped ionization source is able to reproduce the ionization gradients between polar and equatorial regions of the shell. Differences between shell axial ratios in different lines can also be explained by aspherical illumination. A total shell mass of 9 × 10-4 M sun is derived from these models. We estimate that 50%-70% of the shell mass is contained in neutral clumps with density contrast up to a factor of 30.

Moraes, Manoel; Diaz, Marcos

2009-12-01

298

HR Del REMNANT ANATOMY USING TWO-DIMENSIONAL SPECTRAL DATA AND THREE-DIMENSIONAL PHOTOIONIZATION SHELL MODELS  

SciTech Connect

The HR Del nova remnant was observed with the IFU-GMOS at Gemini North. The spatially resolved spectral data cube was used in the kinematic, morphological, and abundance analysis of the ejecta. The line maps show a very clumpy shell with two main symmetric structures. The first one is the outer part of the shell seen in H{alpha}, which forms two rings projected in the sky plane. These ring structures correspond to a closed hourglass shape, first proposed by Harman and O'Brien. The equatorial emission enhancement is caused by the superimposed hourglass structures in the line of sight. The second structure seen only in the [O III] and [N II] maps is located along the polar directions inside the hourglass structure. Abundance gradients between the polar caps and equatorial region were not found. However, the outer part of the shell seems to be less abundant in oxygen and nitrogen than the inner regions. Detailed 2.5-dimensional photoionization modeling of the three-dimensional shell was performed using the mass distribution inferred from the observations and the presence of mass clumps. The resulting model grids are used to constrain the physical properties of the shell as well as the central ionizing source. A sequence of three-dimensional clumpy models including a disk-shaped ionization source is able to reproduce the ionization gradients between polar and equatorial regions of the shell. Differences between shell axial ratios in different lines can also be explained by aspherical illumination. A total shell mass of 9 x 10{sup -4} M {sub sun} is derived from these models. We estimate that 50%-70% of the shell mass is contained in neutral clumps with density contrast up to a factor of 30.

Moraes, Manoel [Rua do Matao, 1226, Cidade Universitaria, Sao Paulo, SP 05508-090 sala F-308 (Brazil); Diaz, Marcos [Rua do Matao, 1226, Cidade Universitaria, Sao Paulo, SP 05508-090 sala F-303 (Brazil)], E-mail: mcvmjr@astro.iag.usp.br, E-mail: marcos@astro.iag.usp.br

2009-12-15

299

Ultrastructural studies on the nematode Xiphinema diversicaudatum: Egg shell formation.  

PubMed

The ultrastructure of the formation of the egg shell in the longidorid nematode Xiphinema diversicaudatum is described. Upon fertilization a vitelline membrane, which constitutes the vitelline layer of the egg shell, is formed. The chitinous layer is secreted in the perivitelline space, between the vitelline layer and the egg cell membrane. On completion of the chitinous layer, the material of the lipid layer is extruded from the egg cytoplasm to the outer surface, through finger-like projections. Both chitinous and lipid layers are secreted by granules in the egg cytoplasm that disappear as the layers are completed. Chitinous and lipid layers are formed during the passage of the egg through the oviduct. The vitelline layer is enriched with secretions produced by the oviduct cells and then by phospholipids secreted by the cells of the pars dilatata oviductus. The inner uterine layer is also formed by deposition of secretory products apposed on the egg shell in the distal uterine region and Z-differentiation. In the proximal part of the uterus, the egg has a discontinuous electron-dense layer, the external uterine layer. Tangential sections between chitinous and uterine layers revealed the presence of holes, possibly egg pores, delimited by the two uterine layers. PMID:18621237

Bleve-Zacheo, T; Melillo, M T; Zacheo, G

1993-06-01

300

Insulative laser shell coupler  

DOEpatents

A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dielectric break ring, and a pair of threaded ring sections is disclosed. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections. 4 figs.

Arnold, P.A.; Anderson, A.T.; Alger, T.W.

1994-09-20

301

Nonlinear Dynamics of Hemispherical Shells.  

National Technical Information Service (NTIS)

The nonlinear dynamic response of a thin, clamped hemispherical shell subjected to a suddenly applied pressure is obtained. The governing fourth order, coupled, nonlinear equations are rewritten in finite difference form and the resulting matrix equation ...

J. M. Klosner R. Longhitano

1972-01-01

302

Nonlinear Theory of Elastic Shells.  

National Technical Information Service (NTIS)

Nonlinear theory of elastic shells is developed which incorporates both geometric and physical nonlinearities and which does not make use of the well known Love-Kirchhoff hypothesis. The resulting equations are formulated in tensorial notation and are red...

J. A. Costa

1979-01-01

303

Spherical Foundation Shell with a Ring Beam  

Microsoft Academic Search

Elastic shell bending theory is applied to the problem of an axisymmetric foundation that consists of two spherical shell segments and a ring beam. The loading consists of a uniform vertical line load applied axisymmetrically on the ring beam. A two parameter foundation model is assumed and shell-beam as well as shell-soil stress and deformation interaction is considered. Theoretical results

D. Redekop; A. K. Sharma

1986-01-01

304

Gas hydrates of outer continental margins  

SciTech Connect

Gas hydrates are crystalline substances in which a rigid framework of water molecules traps molecules of gas, mainly methane. Gas-hydrate deposits are common in continental margin sediment in all major oceans at water depths greater than about 300 m. Thirty-three localities with evidence for gas-hydrate occurrence have been described worldwide. The presence of these gas hydrates has been inferred mainly from anomalous lacoustic reflectors seen on marine seismic records. Naturally occurring marine gas hydrates have been sampled and analyzed at about tensites in several regions including continental slope and rise sediment of the eastern Pacific Ocean and the Gulf of Mexico. Except for some Gulf of Mexico gas hydrate occurrences, the analyzed gas hydrates are composed almost exclusively of microbial methane. Evidence for the microbial origin of methane in gas hydrates includes (1) the inverse relation between methane occurence and sulfate concentration in the sediment, (2) the subparallel depth trends in carbon isotopic compositions of methane and bicarbonate in the interstitial water, and (3) the general range of {sup 13}C depletion ({delta}{sub PDB}{sup 13}C = {minus}90 to {minus}60 {per thousand}) in the methane. Analyses of gas hydrates from the Peruvian outer continental margin in particular illustrate this evidence for microbially generated methane. The total amount of methane in gas hydrates of continental margins is not known, but estimates of about 10{sup 16} m{sup 3} seem reasonable. Although this amount of methane is large, it is not yet clear whether methane hydrates of outer continental margins will ever be a significant energy resource; however, these gas hydrates will probably constitute a drilling hazard when outer continental margins are explored in the future.

Kvenvolden, K.A. (Geological Survey, Menlo Park, CA (USA))

1990-05-01

305

The outer haloes of massive, elliptical galaxies  

NASA Astrophysics Data System (ADS)

The outer haloes of massive elliptical galaxies are dark-matter dominated regions where stellar orbits have longer dynamical timescales than the central regions and therefore better preserve their formation history. Dynamical models out to large radii suffer from a degeneracy between mass and orbital structure, as the outer kinematics are unable to resolve higher moments of the line-of-sight velocity distribution. We mitigate this degeneracy for a sample of quiescent, massive, nearby ellipticals by determining their mass distributions independently using a non-parametric method on X-ray observations of the surrounding hot interstellar medium. We then create dynamical models using photometric and kinematic constraints consisting of integral-eld, long-slit and planetary nebulae (PNe) data extending to ~50 kpc. The rst two galaxies of our sample, NGC 5846 and NGC 1399, were found to have very shallow pro jected light distributions with a power law index of ~1.5 and a dark matter content of 70-80% at 50 kpc. Spherical Jeans models of the data show that, in the outer haloes of both galaxies, the pro jected velocity dispersions are almost inde- pendent of the anisotropy and that the PNe prefer the lower end of the range of mass distributions consistent with the X-ray data. Using the N-body code NMAGIC, we cre- ated axisymmetric models of NGC 5846 using the individual PNe radial velocities in a likelihood method and found them to be more constraining than the binned velocity dispersions. Characterising the orbital structure in terms of spherically averaged proles of the velocity dispersions we nd ?? > ?r > ??.

Das, Payel; Gerhard, Ortwin; de Lorenzi, Flavio; McNeil, Emily; Churazov, Eugene; Coccato, Lodovico

2010-11-01

306

Sea Scallop Shell Lab Handout  

NSDL National Science Digital Library

Used in combination with the Sea Scallop Shell Lab teacher's guide, students will examine sea scallop shells to figure out as much as possible about the scallops living on the sea floor in one three important fishery grounds, Hudson Canyon, off New Bedford, MA, and George's Bank. The activity emphasizes observation, measurements, and basic calculations. The teacher's guide is available from the COSEE-NE OSEI resource site.

307

Membrane Stresses in Axisymmetric Shells  

Microsoft Academic Search

\\u000a A shell is any structure or part of a structure in which one local dimension is much smaller than the other two. Shells abound in\\u000a all branches of engineering and in the natural world. Examples include gas tanks, thin-walled pipes and air ducts, grain hoppers,\\u000a car bodies, aircraft wings and fuselages, window panes, eggshells, wineglasses, concrete roofs and the human

J. R. Barber

308

Nucleonic Shells: a Paradigm Shift?  

Microsoft Academic Search

Shell structure is a fundamental property of leptodermous finite Fermi systems. It results from a one-body motion of weakly interacting quasi-particles in an average mean-field potential. The concept of single-particle motion in nuclei, developed in the late forties, is a cornerstone of nuclear structure. But how robust is this concept? A significant new theme concerns shell structure near the particle

Witold Nazarewicz

2006-01-01

309

The Outer Banks of North Carolina  

USGS Publications Warehouse

Understanding the natural dynamics of barrier islands in the key to recognizing and estimation both the short-term and the long-term hazards of living on them. This report summarizes how the barrier islands were created, how they have changed, and why they will continue to change in spite of efforts to halt the natural processes. The Outer Banks of North Carolina are used as an example in this report, but the principles outlined are applicable to other barrier islands on the Atlantic and Gulf coasts.

Dolan, Robert; Lins, Harry F.

1986-01-01

310

The outer space of a free product  

Microsoft Academic Search

We associate a contractible ``outer space'' to any free product of groups\\u000aG=G_1*...*G_q. It equals Culler-Vogtmann space when G is free,\\u000aMcCullough-Miller space when no G_i is Z. Our proof of contractibility (given\\u000awhen G is not free) is based on Skora's idea of deforming morphisms between\\u000atrees.\\u000a Using the action of Out(G) on this space, we show that Out(G)

Vincent Guirardel; Gilbert Levitt

2006-01-01

311

On the origin of thin detached gas shells around AGB stars: Insights from time-dependent hydrodynamical simulations  

NASA Astrophysics Data System (ADS)

We have applied two different computer codes to study the time-dependent hydrodynamics of circumstellar gas/dust shells of AGB stars in their final stages of evolution. We verify that a presumed short episode of high mass loss translates into a correspondingly narrow, high-density shell moving through the circumstellar envelope at supersonic speed, provided that the mass loss rate, and hence the outflow velocity, is essentially constant during the mass loss `eruption'. In principle, this scenario remains a viable explanation for the existence of the very thin molecular shells recently detected around some carbon-rich AGB stars. We discovered that an alternative mechanism producing very thin shells of greatly enhanced gas density can operate in the dusty outflows from carbon-rich AGB stars: the interaction of a faster inner wind running into a slower outer wind, sweeping up matter at the interface between both type of winds. We show that this mechanism easily leads to the formation of very thin shells without the need to invoke large variations of the mass loss rate on very short time scales. Finally, we demonstrate that a typical He-shell flash produces both a mass loss `eruption' and a two-wind interaction due to the increased outflow velocity during the high mass loss phase, leading to the formation of a thin compressed gas shell. We propose that this mechanism is responsible for the origin of the observed very thin CO shell around the optically visible carbon star TT Cygni.

Steffen, Matthias; Schönberner, Detlef

312

Structural Analysis of CsoS1A and the Protein Shell of the Halothiobacillus neapolitanus Carboxysome  

PubMed Central

The carboxysome is a bacterial organelle that functions to enhance the efficiency of CO2 fixation by encapsulating the enzymes ribulose bisphosphate carboxylase/oxygenase (RuBisCO) and carbonic anhydrase. The outer shell of the carboxysome is reminiscent of a viral capsid, being constructed from many copies of a few small proteins. Here we describe the structure of the shell protein CsoS1A from the chemoautotrophic bacterium Halothiobacillus neapolitanus. The CsoS1A protein forms hexameric units that pack tightly together to form a molecular layer, which is perforated by narrow pores. Sulfate ions, soaked into crystals of CsoS1A, are observed in the pores of the molecular layer, supporting the idea that the pores could be the conduit for negatively charged metabolites such as bicarbonate, which must cross the shell. The problem of diffusion across a semiporous protein shell is discussed, with the conclusion that the shell is sufficiently porous to allow adequate transport of small molecules. The molecular layer formed by CsoS1A is similar to the recently observed layers formed by cyanobacterial carboxysome shell proteins. This similarity supports the argument that the layers observed represent the natural structure of the facets of the carboxysome shell. Insights into carboxysome function are provided by comparisons of the carboxysome shell to viral capsids, and a comparison of its pores to the pores of transmembrane protein channels.

Tsai, Yingssu; Sawaya, Michael R; Cannon, Gordon C; Cai, Fei; Williams, Eric B; Heinhorst, Sabine; Kerfeld, Cheryl A; Yeates, Todd O

2007-01-01

313

On implementation of a nonlinear four node shell finite element for thin multilayered elastic shells  

Microsoft Academic Search

A simple non-linear stress resultant four node shell finite element is presented. The underlying shell theory is developed from the three dimensional continuum theory via standard assumptions on the displacement field. A model for thin shells is obtained by approximating terms describing the shell geometry. In this work the rotation of the shell director is parameterized by the two Euler

B. Brank; F. B. Damjani?; D. Peric

1995-01-01

314

Au(core)/Pd(shell) structures analyzed by high-resolution medium energy ion scattering  

NASA Astrophysics Data System (ADS)

Bimetallic nano-particles taking a core/shell structure dispersed on metal-oxide supports work more efficiently than the mono-metallic ones as heterogeneous catalyst. In order to elucidate the high catalytic activities, it is essential to analyze quantitatively the size and structure of the core/shell particles. Here, we demonstrate that high-resolution medium energy ion scattering (MEIS) spectrometry makes it possible to identify growth of bimetallic core/shell nano-particles and also to determine the average size of core and shell, respectively, together with the size distribution with an accuracy better than 0.1 nm. As an example, Au(core)/Pd(shell) particles with a nominal size (outer diameter) of 2.4 and 3.7 nm prepared by an alcohol reduction technique were analyzed using 120 keV He+ ions. The present analysis clearly showed formation of Au(core)/Pd(shell) structures with almost the same radii as those expected from the chemical preparation condition. Growth of Au/Pd alloyed particles and significant inclusion of Au and Pd mono-metallic particles were ruled out.

Matsumoto, H.; Mitsuhara, K.; Visikovskiy, A.; Akita, T.; Toshima, N.; Kido, Y.

2010-07-01

315

Shell-core bi-layered scaffolds for engineering of vascularized osteon-like structures.  

PubMed

Bottom-up assembly of osteon-like structures into large tissue constructs represents a promising and practical strategy toward the formation of hierarchical cortical bone. Here, a unique two-step approach, i.e., the combination of electrospinning and twin screw extrusion (TSE) techniques was used to fabricate a microfilament/nanofiber shell-core scaffold that could precisely control the spatial distribution of different types of cells to form vascularized osteon-like structures. The scaffold contained a helical outer shell consisting of porous microfilament coils of polycaprolactone (PCL) and biphasic calcium phosphates (BCP) that wound around a hollow electrospun PCL nanofibrous tube (the core). The porous helical shell supported the formation of bone-like tissues, while the luminal surface of nanofibrous core enabled endothelialization to mimic the function of Haversian canal. Culture of mouse pre-osteoblasts (POBs, MC 3T3-E1) onto the coil shells revealed that coils with pitch sizes greater than 135 ?m, in the presence of BCP, favored the proliferation and osteogenic differentiation of POBs. The luminal surface of PCL nanofibrous core supported the adhesion and spreading of mouse endothelial cells (ECs, MS-1) to form a continuous endothelial lining with the function similar to blood vessels. Taken together, the shell-core bi-layered scaffolds with porous, coil-like shell and nanofibrous tubular cores represent a new scaffolding technology base for the creation of osteon analogs. PMID:23896002

Chen, Xuening; Ergun, Asli; Gevgilili, Halil; Ozkan, Seher; Kalyon, Dilhan M; Wang, Hongjun

2013-07-27

316

Osmotic pressure acting on a semipermeable shell immersed in a solution of polyions.  

PubMed

We study theoretically the osmotic equilibria for a shell immersed in a suspension of polyions (e.g., colloids, polyelectrolytes, etc.). The shell is treated as impermeable for polyions, but allowing free diffusion of counterions that permeate inside the shell. From the solution of linearized Poisson-Boltzmann equation, we obtain the distribution of a potential and concentration profiles for polyions and counterions. We then obtain an explicit formula for the excess osmotic pressure of a polyion solution exerted on the shell, which includes a quadratic term in order to provide a self-consistency of a linear theory. As a result this pressure is larger than given by a concentration of polyions at the outer shell boundary obtained within linearized theory. It is, however, always smaller than or equal to the bulk osmotic pressure. This difference is attributed to a repulsive electrostatic disjoining pressure due to an overlap of counterion clouds inside the shell. A comparison with molecular dynamics simulations is provided and demonstrates that although the concentration profiles obtained within a linear theory deviate from simulation data at large potential, the theoretical and simulation pressures are in surprisingly good harmony. PMID:19123526

Tsekov, Roumen; Stukan, Mikhail R; Vinogradova, Olga I

2008-12-28

317

A yolk-shell design for stabilized and scalable li-ion battery alloy anodes.  

PubMed

Silicon is regarded as one of the most promising anode materials for next generation lithium-ion batteries. For use in practical applications, a Si electrode must have high capacity, long cycle life, high efficiency, and the fabrication must be industrially scalable. Here, we design and fabricate a yolk-shell structure to meet all these needs. The fabrication is carried out without special equipment and mostly at room temperature. Commercially available Si nanoparticles are completely sealed inside conformal, thin, self-supporting carbon shells, with rationally designed void space in between the particles and the shell. The well-defined void space allows the Si particles to expand freely without breaking the outer carbon shell, therefore stabilizing the solid-electrolyte interphase on the shell surface. High capacity (?2800 mAh/g at C/10), long cycle life (1000 cycles with 74% capacity retention), and high Coulombic efficiency (99.84%) have been realized in this yolk-shell structured Si electrode. PMID:22551164

Liu, Nian; Wu, Hui; McDowell, Matthew T; Yao, Yan; Wang, Chongmin; Cui, Yi

2012-05-07

318

Tri-soft shell technique.  

PubMed

Soft-shell techniques exist for lower viscosity dispersive with higher viscosity cohesive ophthalmic viscosurgical devices (OVDs) (soft-shell technique [SST]), viscoadaptive OVDs with balanced salt solution (ultimate soft-shell technique), intraoperative floppy-iris syndrome (soft-shell bridge), and many specific modifications for disinserted zonular fibers, frayed iris strands, Fuchs endothelial dystrophy, small holes in the posterior capsule with protruding vitreous, capsular dye use, and others. Soft-shell techniques exist because it is rheologically impossible to control the surgical environment with a single OVD as well as with an ordered combination of rheologically different OVDs. Surgeons frequently confuse these techniques because of their multitude. This paper unifies all SSTs into a single improved tri-soft shell technique (TSST), from which basic specific applications to unusual circumstances are simple and intuitive. As shown with previous SSTs, the TSST allows surgeons to perform complex tasks with greater surgical facility and to protect endothelial cells better than with single OVDs. PMID:23889867

Arshinoff, Steve A; Norman, Richard

2013-08-01

319

Reverse vesicles of ferrum laurate metallosurfactant in non-aqueous solution dried to produce solid shells.  

PubMed

Ferrum laurate [Fe(OOCC(11) H(23))(3)] metallosurfactant can successfully self-assemble into reversed vesicles in organic media such as pure CHCl(3) and a mixed solvent of CHCl(3) and CH(3)OH. Deformed solid vesicles, including collapsed erythrocyte-like and broken hollow shells, were obtained directly by slectively drying the organic solvents. The morphology of the reversed vesicles of metallosurfactant in the organic media to hardly solid shells is maintained and it is ascribed to the evaporation rate of the solvents and the interactions between ferrum laurate and solvents. PMID:22997149

Dong, Renhao; Hao, Jingcheng

2012-09-20

320

Structural basis for the fracture toughness of the shell of the conch Strombus gigas.  

PubMed

Natural composite materials are renowned for their mechanical strength and toughness: despite being highly mineralized, with the organic component constituting not more than a few per cent of the composite material, the fracture toughness exceeds that of single crystals of the pure mineral by two to three orders of magnitude. The judicious placement of the organic matrix, relative to the mineral phase, and the hierarchical structural architecture extending over several distinct length scales both play crucial roles in the mechanical response of natural composites to external loads. Here we use transmission electron microscopy studies and beam bending experiments to show that the resistance of the shell of the conch Strombus gigas to catastrophic fracture can be understood quantitatively by invoking two energy-dissipating mechanisms: multiple microcracking in the outer layers at low mechanical loads, and crack bridging in the shell's tougher middle layers at higher loads. Both mechanisms are intimately associated with the so-called crossed lamellar microarchitecture of the shell, which provides for 'channel' cracking in the outer layers and uncracked structural features that bridge crack surfaces, thereby significantly increasing the work of fracture, and hence the toughness, of the material. Despite a high mineral content of about 99% (by volume) of aragonite, the shell of Strombus gigas can thus be considered a 'ceramic plywood' and can guide the biomimetic design of tough, lightweight structures. PMID:10890440

Kamat, S; Su, X; Ballarini, R; Heuer, A H

2000-06-29

321

Feshbach resonances in inner-shell photodetachment: The case of Te{sup -}  

SciTech Connect

Bound 4d inner-shell excited states have been observed as 4d{sup 10}5s{sup 2}5p{sup 5}{yields}4d{sup 9}5s{sup 2}5p{sup 6} {sup 2}D{sub 5/2,3/2} Feshbach resonances in the photodetachment spectrum of Te{sup -} utilizing the merged-beam technique at the storage ring ASTRID. The strong binding of these core-excited levels, 2.95 and 1.47 eV respectively, is attributed to the extra stability of the full 5p shell. The role of the present data as a prototype spectrum for negative ions having an outer shell with a single vacancy in the initial state is discussed.

Kjeldsen, H.; Folkmann, F.; Jacobsen, T.S.; West, J.B. [Department of Physics and Astronomy, University of Aarhus, DK - 8000 Aarhus C (Denmark); Daresbury Laboratory, Warrington WA4 4AD (United Kingdom)

2004-05-01

322

Polymer shell as a protective layer for the sandwiched gold nanoparticles and their recyclable catalytic property.  

PubMed

Poly(ethyleneglycol methacrylate) (PEGDMA) shell was used as a protective layer for the sandwiched gold nanoparticles, which were prepared through the in situ reduction in the HAuCl4 precursor in the presence of (aminopropyl)trimethoxysilane (APS) modified silica/PEGDMA core-shell microspheres. In this process, the silica/PEGDMA core-shell microspheres were afforded by the distillation-precipitation polymerization of the EGDMA monomer on the APS-modified silica particles with the aid of hydrogen-bonding interaction. The gold nanoparticles were formed at the interface between the silica core and the PEGDMA outer layer through the strong coordinate interaction between the gold nanoparticles and the amino groups on the surface of the silica during the reduction in HAuCl4. The sandwiched gold nanoparticles exhibited highly catalytic efficiency and facile recovery with good stability. PMID:23332796

Liu, Bin; Wang, Xiaoman; Zhao, Yanwei; Wang, Jianchao; Yang, Xinlin

2012-12-26

323

Hard spheres out of equilibrium  

NASA Astrophysics Data System (ADS)

In this thesis, experiments and simulations are combined to investigate the nonequilibrium behaviour of hard spheres. In the first chapters we use Molecular Dynamics simulations to investigate the dynamic glass transition of polydisperse hard spheres. We show that this dynamic transition is accompanied by a thermodynamic signature. The higher-order derivatives of the pressure change abruptly at the dynamic glass transition. If a system is compressed beyond this dynamic transition, the pressure increases until it diverges when the system is completely jammed. The density at which the pressure diverges depends on the compression speed. We proceed with experiments on colloidal polymethylmethacrylate (PMMA) particles which closely resemble hard spheres. We investigate the effect of compression using gravity and electric field gradients on the nucleation and on the glass transition. The transition from glass to crystal is gradual and is strongly effected by gravity. We go back to computer simulations to investigate two different techniques to calculate the rate at which a hard-sphere system nucleates. We find that the two techniques yield similar results for the nucleation rate as well as the critical nucleus shape. From this we conclude that the simulation techniques are valid. A combination of simulations and experiments is used to study the nucleation of hard spheres on seed structures. We initiate the nucleation with a seed of particles kept in place by optical tweezers. We show that whereas the nucleation itself can be well described as an equilibrium process, the growth after nucleation can not. We demonstrate that defects play an important role in the growth of the crystal. Colloidal hard spheres can also be driven out of equilibrium using shear. We perform experiments on an equilibrium fluid phase below the coexistence density of the fluid. We show that we can induce order in an equilibrium fluid using oscillatory shear. We find five different phases for varying frequency and amplitude: four known phases and one new phase. The formation of all phases occurs via nucleation and growth and the melting, when the shear is stopped, starts on the edges and near the defects of the crystal phases. In the final chapter, we investigate the interactions between rough colloidal particles in the presence of polymers. We investigate whether surface roughness can be used to reduce the depletion attraction. We find that when the polymer is smaller than the surface roughness the attraction can be reduced significantly compared to smooth colloids.

Hermes, M.

2010-05-01

324

What Happened in the Outer Solar System?  

NASA Astrophysics Data System (ADS)

The Kuiper belt was initially envisioned as a thin disk of proto-cometary bodies slowly decreasing in number beyond the edge of the known planetary system. The first insights that the Kuiper belt was more complicated were from Malhotra, who realized that the dynamical distribution of objects in the Kuiper belt preserves the signature of an early episode of planetary migration, and by Stern, who showed that the numbers, masses, and velocities of objects currently in the Kuiper belt imply that significant mass depletion and velocity evolution must have occurred in earlier times. Increasingly detailed observations and analyses of the Kuiper belt are showing increasingly complex deviations from the original simplistic view. Using a variety of techniques, I will demonstrate that the inclination distribution of the classical Kuiper belt shows two dynamically distinct populations interspersed, that the radial distribution of Kuiper belt objects shows a sharp edge beyond about 48 AU, that the colors of classical Kuiper belt objects appear correlated with inclination, and that the spectra of Kuiper belt objects show large variability. I will attempt to synthesize a coherent picture of the outer solar system from these disparate observations and answer the question of what happened in the outer solar system.

Brown, M. E.

2001-11-01

325

Residual Stress Testing of Outer 3013 Containers  

SciTech Connect

A Gas Tungsten Arc Welded (GTAW) outer 3013 container and a laser welded outer 3013 container have been tested for residual stresses according to the American Society for Testing Materials (ASTM) Standard G-36-94 [1]. This ASTM standard describes a procedure for conducting stress-corrosion cracking tests in boiling magnesium chloride (MgCl2) solution. Container sections in both the as-fabricated condition as well as the closure welded condition were evaluated. Significantly large residual stresses were observed in the bottom half of the as-fabricated container, a result of the base to can fabrication weld because through wall cracks were observed perpendicular to the weld. This observation indicates that regardless of the closure weld technique, sufficient residual stresses exist in the as-fabricated container to provide the stress necessary for stress corrosion cracking of the container, at the base fabrication weld. Additionally, sufficiently high residual stresses were observed in both the lid and the body of the GTAW as well as the laser closure welded containers. The stresses are oriented perpendicular to the closure weld in both the container lid and the container body. Although the boiling MgCl2 test is not a quantitative test, a comparison of the test results from the closure welds shows that there are noticeably more through wall cracks in the laser closure welded container than in the GTAW closure welded container.

Dunn, K.

2004-02-12

326

Future exploration of the outer solar system  

NASA Astrophysics Data System (ADS)

Exploration of the outer solar system is constrained by vast distances, consequent communications and light time limitations, power, and long flight times. Early reconnaissance missions (Pioneer 10 and 11, Voyager 1 and 2) employed relatively fast trajectories resulting in very fast fly-bys. The next generation of exploration (Galileo and Cassini) has been characterized by spacecraft with large propellant systems and relatively slow (gravity assist) trajectories needed energetically to achieve orbit around Jupiter and Saturn. All of these spacecraft utilized radioisotope thermoelectric generators for reliable, but modest power. Future exploration priorities require highly capable spacecraft systems that go into orbit around the primary planet and then perform multiple tasks (e.g. orbiting individual moons and delivering surface and atmospheric scientific probes). To achieve major scientific advances will require significant increases in communication rates, improved instrumentation and high power available for experiments. Fission-powered nuclear electric propulsion is being studied to meet these requirements. A Jupiter Icy Moons Orbiter is proposed as the first of this class of new, highly capable missions. The paper will review the scientific rationale for the JIMO mission and prospects for applying these techniques to exploration of Saturn and the other outer planets.

Johnson, T.

327

Hard Photodisintegration of 3He  

NASA Astrophysics Data System (ADS)

Large angle photodisintegration of two nucleons from the 3He nucleus is studied within the framework of the hard rescattering model (HRM). In the HRM the incoming photon is absorbed by one nucleon's valence quark that then undergoes a hard rescattering reaction with a valence quark from the second nucleon producing two nucleons emerging at large transverse momentum . Parameter free cross sections for pp and pn break up channels are calculated through the input of experimental cross sections on pp and pn elastic scattering. The calculated cross section for pp breakup and its predicted energy dependency are in good agreement with recent experimental data. Predictions on spectator momentum distributions and helicity transfer are also presented.

Granados, Carlos

2011-02-01

328

Weld cladding of hard surfaces  

NASA Astrophysics Data System (ADS)

A literature study about clad welding of hard surfaces on steel is performed. The purpose was to see what kind of methods are mainly used, and particular attention is paid to clad welding of rolls. The main impression from this study is that several methods are in use. Some of these must be considered as 'too exotic' for the aim of the program, such as laser build-up welding. However, clad welding of hard surfaces to rolls is widely used around the world, and there is no need for particularly advanced welding methods to perform the work. The welding consumables and the way the welding is carried out is of more important character. The report will give some comments to this, and hopefully will give a short review of the current technology in this field.

Habrekke, T.

1993-02-01

329

Ultrasonic material hardness depth measurement  

DOEpatents

The invention is an ultrasonic surface hardness depth measurement apparatus and method permitting rapid determination of hardness depth of shafts, rods, tubes and other cylindrical parts. The apparatus of the invention has a part handler, sensor, ultrasonic electronics component, computer, computer instruction sets, and may include a display screen. The part handler has a vessel filled with a couplant, and a part rotator for rotating a cylindrical metal part with respect to the sensor. The part handler further has a surface follower upon which the sensor is mounted, thereby maintaining a constant distance between the sensor and the exterior surface of the cylindrical metal part. The sensor is mounted so that a front surface of the sensor is within the vessel with couplant between the front surface of the sensor and the part.

Good, Morris S. (Richland, WA); Schuster, George J. (Kennewick, WA); Skorpik, James R. (Kennewick, WA)

1997-01-01

330

Highly-resolved 2D HYDRA simulations of Double-Shell Ignition Designs  

SciTech Connect

Double-shell (DS) targets (Amendt, P. A. et al., 2002) offer a complementary approach to the cryogenic baseline design (Lindl, J. et al., 2004) for achieving ignition on the National Ignition Facility (NIF). Among the expected benefits are the ease of room temperature preparation and fielding, the potential for lower laser backscatter and the reduced need for careful shock timing. These benefits are offset, however, by demanding fabrication tolerances, e.g., shell concentricity and shell surface smoothness. In particular, the latter is of paramount importance since DS targets are susceptible to the growth of interface perturbations from impulsive and time-dependent accelerations. Previous work (Milovich, J. L. et al., 2004) has indicated that the growth of perturbations on the outer surface of the inner shell is potentially disruptive. To control this instability new designs have been proposed requiring bimetallic inner shells and material-matching mid-Z nanoporous foam. The challenges in manufacturing such exotic foams have led to a further evaluation of the densities and pore sizes needed to reduce the seeding of perturbations on the outer surface of the inner shell, thereby guiding the ongoing material science research efforts. Highly-resolved 2D simulations of porous foams have been performed to establish an upper limit on the allowable pore sizes for instability growth. Simulations indicate that foams with higher densities than previously thought are now possible. Moreover, while at the present time we are only able to simulate foams with average pore sizes larger than 1 micron (due to computational limitations), we can conclude that these pore sizes are potentially problematic. Furthermore, the effect of low-order hohlraum radiation asymmetries on the growth of intrinsic surface perturbations is also addressed. Highly-resolved 2D simulations indicate that the transverse flows that are set up by these low-order mode features (which can excite Kelvin-Helmholtz instabilities) are not large enough to offset the overall robustness of our current design.

Milovich, J L; Amendt, P; Hamza, A; Marinak, M; Robey, H

2006-06-30

331

Acinetobacter baumannii Secretes Cytotoxic Outer Membrane Protein A via Outer Membrane Vesicles  

Microsoft Academic Search

Acinetobacter baumannii is an important nosocomial pathogen that causes a high morbidity and mortality rate in infected patients, but pathogenic mechanisms of this microorganism regarding the secretion and delivery of virulence factors to host cells have not been characterized. Gram-negative bacteria naturally secrete outer membrane vesicles (OMVs) that play a role in the delivery of virulence factors to host cells.

Jong Sook Jin; Sang-Oh Kwon; Dong Chan Moon; Mamata Gurung; Jung Hwa Lee; Seung Il Kim; Je Chul Lee; Stefan Bereswill

2011-01-01

332

Isolation of the outer membrane and characterization of the major outer membrane protein from Spirochaeta aurantia.  

PubMed Central

The outer membrane of Spirochaeta aurantia was isolated after cells were extracted with sodium lauryl sarcosinate and was subsequently purified by differential centrifugation and KBr isopycnic gradient centrifugation. The purified outer membrane was obtained in the form of carotenoid-containing vesicles. Four protein species with apparent molecular weights of 26,000 (26K), 36.5K, 41K, and 48.5K were readily observed as components of the vesicles. The 36.5K protein was the major polypeptide and constituted approximately 90% of the outer membrane protein observed on sodium dodecyl sulfate-polyacrylamide gels. Under mild denaturing conditions the 36.5K major protein exhibited an apparent molecular weight of approximately 90,000. This, together with the results of protein cross-linking studies, indicates that the 36.5K polypeptide has an oligomeric conformation in the native state. Reconstitution of solubilized S. aurantia outer membrane into lipid bilayer membranes revealed the presence of a porin, presumably the 36.5K protein, with an estimated channel diameter of 2.3 nm based on the measured single channel conductance of 7.7 nS in 1 M KCl. Images

Kropinski, A M; Parr, T R; Angus, B L; Hancock, R E; Ghiorse, W C; Greenberg, E P

1987-01-01

333

Cyclic strength of hard metals  

Microsoft Academic Search

The fatigue limit of the titanium carbide and tungsten carbide alloys investigated on a basis of 5·108 cycles lies in the range (20–30)·107 Pa, and is thus comparable with the endurance of type ShKh high-carbon (~1% C-Mn-Si-Cr) ball-bearing steels. The strength and character of fracture of the hard metals are determined by the properties and structural state of their phase

N. N. Sereda; A. K. Gerikhanov; M. S. Koval'chenko; L. G. Pedanov

1985-01-01

334

BGO crystals - radiation hard scintillators  

Microsoft Academic Search

A new version of the Bridgman technique of Bi4Ge3O12 (BGO) crystal growth was developed. The first radiation hardness measurement of new BGO grown by this technique shows excellent characteristics. The optical transmission at a peak emission 0.48 mum of these crystals degraded by no more than 10% when irradiated by photons from 60Co decay up to a total dose of

V. V. Yanovsky; V. A. Chizhov; V. M. Skorikov

1991-01-01

335

Splitting (complicated) surfaces is hard  

Microsoft Academic Search

Let M be an orientable combinatorial surface. A cycle on M is splitting if it has no self-intersections and it partitions M into two components, neither of which is homeomorphic to a disk. In other words, splitting cycles are simple, separating, and non-contractible. We prove that finding the shortest splitting cycle on a combinatorial surface is NP-hard but fixed-parameter tractable

Erin W. Chambers; Éric Colin De Verdière; Jeff Erickson; Francis Lazarus; Kim Whittlesey

2008-01-01

336

Splitting (complicated) surfaces is hard  

Microsoft Academic Search

Let M be an orientable surface without boundary. A cycle on M is splitting if it has no self-intersections and it partitions M into two components, neither homeomorphic to a disk. In other words, splitting cycles are simple, separating, and non-contractible. We prove that finding the shortest splitting cycle on a combinatorial surface is NP-hard but fixed-parameter tractable with respect

Erin W. Chambers; Éric Colin De Verdière; Jeff Erickson; Francis Lazarus; Kim Whittlesey

2006-01-01

337

What's on Your Hard Drive?  

Microsoft Academic Search

What’s on Your Hard Drive? Whether you love ’em or hate ’em, dev tools play an integral role in a programmer’s existence. They were (hopefully!) designed to make your job easier, although all too often the exact opposite seems to be the case. Is there a tool so exceptionally brilliant that you just can’t live without it? Have you encountered

Charlene O'Hanlon

2006-01-01

338

Studies on dynamic behavior of composite and isotropic cylindrical shells with PZT layers under axisymmetric temperature variation  

NASA Astrophysics Data System (ADS)

A comparative study is presented on the vibratory characteristics of isotropic and orthotropic cylindrical shells with perfectly bonded piezoelectric material on the inner and outer surface of the shell lamina. The variation of free vibration natural frequencies and active damping ratios are simulated under varying magnitude of steady state axisymmetric temperatures. The objectives are explained by presenting the results of the numerical study on cylindrical shells made of mild steel and HS-graphite/epoxy bonded with PZT piezoelectric material. The vibratory characteristics under the above circumstances are interpreted from the point of view of initial stresses developed due to thermal loading. Apart from this, the changes in the vibratory characteristics due to different fiber orientations are examined. It is found from the studies that the frequency characteristic with respect to fiber orientation under thermal environment is highly dependent on the boundary condition considered for the shell laminate.

Kadoli, Ravikiran; Ganesan, N.

2004-03-01

339

Impact of aging on radiation hardness  

SciTech Connect

Burn-in effects are used to demonstrate the potential impact of thermally activated aging effects on functional and parametric radiation hardness. These results have implications on hardness assurance testing. Techniques for characterizing aging effects are proposed.

Shaneyfelt, M.R.; Winokur, P.S.; Fleetwood, D.M. [and others

1997-07-01

340

Hard x-ray and hot electron environment in vacuum hohlraums at the National Ignition Facility  

SciTech Connect

Time resolved hard x-ray images (hv>9 keV) and time integrated hard x-ray spectra (hv=18-150 keV) from vacuum hohlraums irradiated with four 351 nm wavelength National Ignition Facility [J. A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Technol. 26, 755 (1994)] laser beams are presented as a function of hohlraum size, laser power, and duration. The hard x-ray images and spectra provide insight into the time evolution of the hohlraum plasma filling and the production of hot electrons. The fraction of laser energy detected as hot electrons (F{sub hot}) shows a correlation with laser intensity and with an empirical hohlraum plasma filling model. In addition, the significance of Au K-alpha emission and Au K-shell reabsorption observed in some of the bremsstrahlung dominated spectra is discussed.

McDonald, J.W.; Suter, L.J.; Landen, O.L.; Foster, J.M.; Celeste, J.R.; Holder, J.P.; Dewald, E.L.; Schneider, M.B.; Hinkel, D.E.; Kauffman, R.L.; Atherton, L.J.; Bonanno, R.E.; Dixit, S.N.; Eder, D.C.; Haynam, C.A.; Kalantar, D.H.; Koniges, A.E.; Lee, F.D.; MacGowan, B.J.; Manes, K.R. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)] (and others)

2006-03-15

341

A survey of the anisotropy of the outer electron radiation belt during high-speed-stream-driven storms  

NASA Astrophysics Data System (ADS)

Electron measurements on board six spacecraft in geosynchronous orbit are superposed-epoch analyzed for 42 high-speed-stream-driven storms. Using pitch angle-resolved fluxes in the range 30 keV to 1.7 MeV, the evolution of the outer electron radiation belt and the suprathermal tail of the electron plasma sheet are studied. The outer electron radiation belt exhibits perpendicular-dominated anisotropies on the dayside and parallel-dominated anisotropies on the nightside consistent with shell splitting in a distorted magnetosphere. The magnitudes of the radiation-belt anisotropies are weak prior to storm onset and become very large during the storms. The magnitudes of the anisotropies lessen with time as the storm ages and the radiation belt heats, probably owing to a weakening of the magnetic field distortion as the storm ages. When a calm before the storm occurs, the dayside radiation belt approaches isotropy, probably owing to pitch angle scattering in the outer plasmasphere that fills during the calm. If no calm before the storm occurs, the dayside radiation belt is strongly perpendicular dominated. The local-time pattern of anisotropy in storms is very different for the suprathermal tail of the electron plasma sheet, which tends to be perpendicular on the nightside and isotropic elsewhere. The magnitudes of the anisotropies of the suprathermal tail are a factor of ˜10 weaker than the anisotropies of the outer electron radiation belt.

Borovsky, Joseph E.; Denton, Michael H.

2011-05-01

342

ONE-DIMENSIONAL ACCELERATOR IN PULSAR OUTER MAGNETOSPHERE REVISITED  

SciTech Connect

We re-examine the one-dimensional (1D) vacuum and nonvacuum accelerators in the outer magnetosphere of rotation-powered pulsars by considering the limit of trans-field height through pair-production process. In the original 1D nonvacuum outer gap model, both the Poisson equation for electrical potential and the Boltzmann equations of particles and gamma-rays are solved self-consistently by assuming the trans-field height as a free parameter, usually resulting in a narrow outer gap (i.e., gap length along magnetic field lines is short). In the modified 1D nonvacuum outer gap model, two improvements have been made: the trans-field height is limited by photon-photon pair production process and the outer boundary of the outer gap can be extended outside the light cylinder. Under the above assumptions, we self-consistently solve the Poisson equation for electrical potential, and the Boltzmann equations of electrons/positrons and gamma-rays in both vacuum and nonvacuum outer gaps for the parameters of both Vela and Geminga pulsars. We obtain an approximate geometry of the outer gap, i.e., the trans-field height is limited by the pair-production process and increases with the radial distance to the star, and the width of the outer gap starts at the inner boundary (near the null charge surface in the vacuum case) and ends at the outer boundary which is located inside or outside the light cylinder depending on the inclination angle. Our calculated results also indicate that gamma-ray spectrum from a wide outer gap is flatter than the one from a narrow outer gap and the relation between the electric field and trans-field height has an important effect on the structure of the outer gap.

Lin, G. F.; Zhang, L., E-mail: lizhang@ynu.edu.c [Department of Physics, Yunnan University, Kunming (China)

2009-07-10

343

Radio seismology of the outer solar corona  

NASA Astrophysics Data System (ADS)

Context. Observed oscillations of coronal loops in extreme ultraviolet (EUV) lines have been successfully used to estimate plasma parameters in the inner corona (<0.2 R0, where R0 is the solar radius). However, coronal seismology in EUV lines fails for higher altitudes because of rapid decrease in line intensity. Aims: We aim to use radio observations to estimate the plasma parameters of the outer solar corona (>0.2 R0). Methods: We used the large Ukrainian radio telescope URAN-2 to observe type IV radio bursts at the frequency range of 8-32 MHz during the time interval of 09:50-12:30 UT on April 14, 2011. The burst was connected to C2.3 flare, which occurred in AR 11190 during 09:38-09:49 UT. The dynamic spectrum of radio emission shows clear quasi-periodic variations in the emission intensity at almost all frequencies. Results: Wavelet analysis at four different frequencies (29 MHz, 25 MHz, 22 MHz, and 14 MHz) shows the quasi-periodic variation of emission intensity with periods of ~34 min and ~23 min. The periodic variations can be explained by the first and second harmonics of vertical kink oscillation of transequatorial coronal loops, which were excited by the same flare. The apex of transequatorial loops may reach up to 1.2 R0 altitude. We derive and solve the dispersion relation of trapped magnetohydrodynamic oscillations in a longitudinally inhomogeneous magnetic slab. The analysis shows that a thin (with width to length ratio of 0.1), dense (with the ratio of internal and external densities of ?20) magnetic slab with weak longitudinal inhomogeneity of the Alfvén speed may trap the observed oscillations. Seismologically estimated Alfvén speed inside the loop at the height of ~1 R0 is ~1000 km s-1. The magnetic field strength at this height is estimated as ~0.9 G. Extrapolation of magnetic field strength to the inner corona gives ~10 G at the height of 0.1 R0. Conclusions: Radio observations can be successfully used for the sounding of the outer solar corona, where EUV observations of coronal loops fail. Therefore, radio seismology of the outer solar corona is complementary to EUV seismology of the inner corona.

Zaqarashvili, T. V.; Melnik, V. N.; Brazhenko, A. I.; Panchenko, M.; Konovalenko, A. A.; Franzuzenko, A. V.; Dorovskyy, V. V.; Rucker, H. O.

2013-07-01

344

Low Temperature Processing of Core-Shell Baroplastics  

NASA Astrophysics Data System (ADS)

Baroplastics are nanophase materials that exhibit the ability to flow and be molded under pressure at reduced temperatures. Core-shell nanoparticle baroplastics comprised of one soft component, such as poly(butyl acrylate), and one glassy component, such as polystyrene, were synthesized by miniemulsion polymerization and processed at temperature as low as 25^oC by compression molding and extrusion. The resulting specimens are clear and well-defined solid objects with a diverse range of mechanical properties depending on composition, ranging from tough, rigid materials to rubbery materials comparable to commercial thermoplastic elastomers. SANS and DSC measurements on the core-shell materials before and after processing reveal pressure induced partial mixing of the hard and soft components, while TEM studies show that the core-shell morphology is substantially retained, even after 20 reprocessing cycles. Mechanical properties of the processed samples were measured to elucidate the effects of processing pressure and temperature and to isolate the role of the pressure-induced miscibility.

Gonzalez Leon, Juan A.

2005-03-01

345

Surface Integrity Generated by Precision Hard Turning  

Microsoft Academic Search

Rolling contact fatigue tests were conducted to find the effect of precision hard turning. The tests showed that hard turning provides as good a fatigue performance as grinding. Hard turning produces compressive residual stresses in a deep subsurface, which contribute to a long fatigue life. The effect of cutting parameters on residual stress was investigated in order to find why

Y. Matsumoto; F. Hashimoto; G. Lahoti

1999-01-01

346

Plasmons for Coulomb Coupled Spherical Shells  

NASA Astrophysics Data System (ADS)

We report calculations of the collective plasmon excitations for an electron gas confined to the surface of a spherical shell. The energy spectra of the plasmons and particle-hole modes are presented as functions of the radius of the shell as well as the angular momentum quantum number L. We compare results for the plasma excitations for a single shell, a pair of concentric shells as well as when two shells have their centers separated by a distance which exceeds the sum of the radii of the two shells. For the single shell and pair of concentric shells, the plasma modes are labelled by the angular momentum quantum number L only. However, for the pair of non-concentric shells, the plasma modes are labelled by both L and M, the projection of angular momentum on the z axis. These results have been obtained in the random phase approximation (RPA).

Balassis, Antonios; Iurov, Andrii; Gumbs, Godfrey

2013-03-01

347

The outer boundary of the earth's electron radiation belt: Dependence upon L, energy, and equatorial pitch angle  

SciTech Connect

The authors present measurements of electrons made with high energy and pitch angle resolution, made at the equator, looking over a range of L shells in the neighborhood of the nightside trapping boundary. They define the trapping boundary to be the position where the trapped fluxes are equivalent to the background level. The transition region is studied in detail. Fine scale experimental measurements are of use in bringing together theoretical models which attempt to explain precipitating electrons from the outer boundary of the earth's electron radiation belt, with the broad range of measurements which are presently available. They took advantage of the measurement capabilities of the CRRES and SCATHA satellites for this work.

Imhof, W.L.; Robinson, R.M.; Nightingale, R.W.; Gaines, E.E.; Vondrak, R.R. (Lockheed Palo Alto Research Lab., CA (United States))

1993-04-01

348

Shell optimizes beta field completions  

SciTech Connect

Shell California Production Inc., a subsidiary of Shell Oil Co., has developed innovative perforating, washing, and gravel packing techniques to optimize production rates of the Beta field, offshore Long Beach, Calif. Field development is complicated because the heavy oil reservior, which consists of nine separate, unconsolidated sand intervals, lies at a shallow depth, with the gross pay section as thick as 1,200 ft (Figs. 1 and 2). To develop these sands economically, using only two drilling platforms, and to be able to initiate an early waterflood, Shell designed the wells to have: Highly deviated, S-shaped well bores. Isolated, multizone completions, capable of being selectively produced from or injected into for any combination of zones (Fig. 3). Sand-free production, so performance of the electrical submersible pumps used for artificial lift is not impeded. When perforating the wells, Shell selected and modified a tubing-conveyed perforating system. In addition, as part of the completion program, Shell developed inside casing gravel packing tools to optimize selective, multizone, one-trip gravel pack operations.

Moore, S.D.

1983-12-01

349

Shell models of magnetohydrodynamic turbulence  

NASA Astrophysics Data System (ADS)

Shell models of hydrodynamic turbulence originated in the seventies. Their main aim was to describe the statistics of homogeneous and isotropic turbulence in spectral space, using a simple set of ordinary differential equations. In the eighties, shell models of magnetohydrodynamic (MHD) turbulence emerged based on the same principles as their hydrodynamic counter-part but also incorporating interactions between magnetic and velocity fields. In recent years, significant improvements have been made such as the inclusion of non-local interactions and appropriate definitions for helicities. Though shell models cannot account for the spatial complexity of MHD turbulence, their dynamics are not over simplified and do reflect those of real MHD turbulence including intermittency or chaotic reversals of large-scale modes. Furthermore, these models use realistic values for dimensionless parameters (high kinetic and magnetic Reynolds numbers, low or high magnetic Prandtl number) allowing extended inertial range and accurate dissipation rate. Using modern computers it is difficult to attain an inertial range of three decades with direct numerical simulations, whereas eight are possible using shell models.In this review we set up a general mathematical framework allowing the description of any MHD shell model. The variety of the latter, with their advantages and weaknesses, is introduced. Finally we consider a number of applications, dealing with free-decaying MHD turbulence, dynamo action, Alfvén waves and the Hall effect.

Plunian, Franck; Stepanov, Rodion; Frick, Peter

2013-02-01

350

US outer continental shelf petroleum resources  

SciTech Connect

Despite the need to develop US petroleum resources on the outer continental shelf (OCS), controversy and uncertainty continue over the establishment of a ''proper policy'' for the OCS. Following a brief background review of the history of OCS legislation, the authors survey recent empirical investigations into the problems and prospects of competitive leasing and development that cover industry concentration, bidding patterns, and rate of return. They also describe ecological issues affecting exploration and development in the OCS regions. The conflict between energy resource issues and environmental issues in this area revolves around the question of acceptable levels of economic sanctions and environmental protection coincident with the optimal level of exploration and developement activity. 20 references.

Desvousges, W.H.; Piette, M.J.

1984-04-01

351

Outer solar system for 200 million years  

SciTech Connect

A special-purpose computer is used to integrate the orbits of the outer five planets for more than 100 Myr into the future and more than 100 Myr into the past. The strongest features in the Fourier transforms of the orbital elements of the Jovian planets can be identified with the frequencies predicted by linear secular theory. Many of the weaker features in the Fourier spectra are identified as linear combinations of the basic frequencies. Serious differences are noted between the present measurements and the predictions of Bretagnon (1974). The amplitude of the 3.796 Myr period libration of Pluto's longitude of perihelion is modulated with a period of 34 Myr. Very long periods, on the order of 137 Myr, are also seen. The orbit of Pluto is stable for the duration of the integration; the maximum Liapunov characteristic exponent is less than 10 to the -6.8 power/yr. 21 references.

Applegate, J.H.; Douglas, M.R.; Gursel, Y.; Sussman, G.J.; Wisdom, J.

1986-07-01

352

Investigation of shell cracking on the steam generators at Indian Point Unit No. 3  

SciTech Connect

A metallurgical investigation was performed on specimens from the shell of steam generators No. 31 and 32 of the Indian Point 3 Power Plant. The examination consisted of optical microscopy, SEM/EDS, hardness measurements, and two different heat treatments. The shell material exhibited high values in hardness prior to the heat treatments, which was indicative that relatively high residual stresses may have been present in the areas of the welds. All observed cracks were transgranular in appearance and were associated with pits on the vessel's inside surfaces. Beach marks were observed on a fracture face from steam generator No. 32, as well as possible fatigue striations. The report concludes that the cracking was caused by a low cycle corrosion fatigue phenomenon with cracks initiating at areas of localized corrosion and propagating by fatigue.

Czajkowski, C.J.

1983-06-01

353

Shell disturbances and butyltins burden in commercial bivalves collected from the Bizerta lagoon (northern Tunisia).  

PubMed

Shell disturbances and soft tissues butyltin burden were investigated in commercial bivalves Lithophaga lithophaga, Mytilus galloprovincialis, Solen marginatus and Crassostrea gigas from the Bizerta lagoon. Shell disturbances were found in all bivalves, being scarce in S. marginatus. In the internal valve of L. lithophaga, burrowing annelids and sipunculids living inside galleries were observed, while in the external valve, brown-blackish or white stains were found. In M. galloprovincialis, a yellowish mass located at the shell anterior side was found fixed firmly to the pearly layer by a hard brownish structure covering some annelid elliptic eggs. In the internal shell layer of some specimens collected in April, embryos belonging to tubiculous annelids at various developmental stages were observed. In C. gigas, shell thickening was revealed in some specimens corresponding to white doughy deposits at the internal valve and between shell layers. In S. marginatus, only one specimen showing a cavity at the posterior site was found. Total butyltin concentrations in the studied bivalves varied between 30 and 245 ng/g dry weight with tributyltin (TBT) being the predominant compound. The highest concentration was recorded in L. lithophaga collected from the Bizerta Bay and the lowest concentration in S. marginatus from Maghraoua. This study provided baseline data that could serve for long-term monitoring of TBT pollution in Tunisia, since legislation to reduce the use of TBT-based antifouling paints has not been introduced yet. PMID:22170157

Kefi, Ferdaous Jaafar; Lahbib, Youssef; Abdallah, Lamia Gargouri Ben; El Menif, Najoua Trigui

2011-12-15

354

Alternative mechanisms of increased eggshell hardness of avian brood parasites relative to host species  

PubMed Central

Obligate brood parasitic birds lay their eggs in nests of other species and parasite eggs typically have evolved greater structural strength relative to host eggs. Increased mechanical strength of the parasite eggshell is an adaptation that can interfere with puncture ejection behaviours of discriminating hosts. We investigated whether hardness of eggshells is related to differences between physical and chemical traits from three different races of the parasitic common cuckoo Cuculus canorus, and their respective hosts. Using tools developed for materials science, we discovered a novel correlate of increased strength of parasite eggs: the common cuckoo's egg exhibits a greater microhardness, especially in the inner region of the shell matrix, relative to its host and sympatric non-host species. We then tested predictions of four potential mechanisms of shell strength: (i) increased relative thickness overall, (ii) greater proportion of the structurally harder shell layers, (iii) higher concentration of inorganic components in the shell matrix, and (iv) elevated deposition of a high density compound, MgCO3, in the shell matrix. We confirmed support only for hypothesis (i). Eggshell characteristics did not differ between parasite eggs sampled from different host nests in distant geographical sites, suggesting an evolutionarily shared microstructural mechanism of stronger parasite eggshells across diverse host-races of brood parasitic cuckoos.

Igic, Branislav; Braganza, Kim; Hyland, Margaret M.; Silyn-Roberts, Heather; Cassey, Phillip; Grim, Tomas; Rutila, Jarkko; Moskat, Csaba; Hauber, Mark E.

2011-01-01

355

Alternative mechanisms of increased eggshell hardness of avian brood parasites relative to host species.  

PubMed

Obligate brood parasitic birds lay their eggs in nests of other species and parasite eggs typically have evolved greater structural strength relative to host eggs. Increased mechanical strength of the parasite eggshell is an adaptation that can interfere with puncture ejection behaviours of discriminating hosts. We investigated whether hardness of eggshells is related to differences between physical and chemical traits from three different races of the parasitic common cuckoo Cuculus canorus, and their respective hosts. Using tools developed for materials science, we discovered a novel correlate of increased strength of parasite eggs: the common cuckoo's egg exhibits a greater microhardness, especially in the inner region of the shell matrix, relative to its host and sympatric non-host species. We then tested predictions of four potential mechanisms of shell strength: (i) increased relative thickness overall, (ii) greater proportion of the structurally harder shell layers, (iii) higher concentration of inorganic components in the shell matrix, and (iv) elevated deposition of a high density compound, MgCO(3), in the shell matrix. We confirmed support only for hypothesis (i). Eggshell characteristics did not differ between parasite eggs sampled from different host nests in distant geographical sites, suggesting an evolutionarily shared microstructural mechanism of stronger parasite eggshells across diverse host-races of brood parasitic cuckoos. PMID:21561966

Igic, Branislav; Braganza, Kim; Hyland, Margaret M; Silyn-Roberts, Heather; Cassey, Phillip; Grim, Tomas; Rutila, Jarkko; Moskát, Csaba; Hauber, Mark E

2011-05-11

356

Plastic buckling of cylindrical shells  

SciTech Connect

Cylindrical shells exhibit buckling under axial loads at stresses much less than the respective theoretical critical stresses. This is due primarily to the presence of geometrical imperfections even through such imperfections could be very small (e.g., comparable to thickness). Under internal pressure, the shell regains some of its buckling strength. For a relatively large radius-to-tickness ratio and low internal pressure, the effect can be reasonably estimated by an elastic analysis. However, for low radius-to-thickness ratios and greater pressures, the elastic-plastic collapse controls the failure load. In order to quantify the elastic-plastic buckling capacity of cylindrical shells, an analysis program was carried out by use of the computer code BOSOR5 developed by Bushnell of Lockheed Missiles and Space company. The analysis was performed for various radius-to- thickness ratios and imperfection amplitudes. The analysis results are presented in this paper.

Bandyopadhyay, K.; Xu, J.; Shteyngart, S. [Brookhaven National Lab., Upton, NY (United States); Eckert, H. [USDOE, Germantown, MD (United States)

1994-05-01

357

The maximum hardness principle implies the hard/soft acid/base rule  

NASA Astrophysics Data System (ADS)

A recent paper [P. W. Ayers, J. Chem. Phys122, 141102 (2005)] considered the hard/soft acid/base exchange reaction, showing that the products associated with the hard/soft acid/base rule (in which the hard acid and hard base are bound, as are the soft acid and soft base) have lower energy than the alternative (in which the hard acid and soft base would have been bound and similarly the soft acid and hard base). Here we show that the maximum hardness principle also predicts this result. Unlike the previous derivation, we do not need to make any assumptions about the relative strength of the acids and bases.

Chattaraj, Pratim K.; Ayers, Paul W.

2005-08-01

358

Corrugated outer sheath gas-insulated transmission line  

DOEpatents

A gas-insulated transmission line includes two transmission line sections each of which are formed of a corrugated outer housing enclosing an inner high-voltage conductor disposed therein, with insulating support means supporting the inner conductor within the outer housing and an insulating gas providing electrical insulation therebetween. The outer housings in each section have smooth end sections at the longitudinal ends thereof which are joined together by joining means which provide for a sealing fixed joint.

Kemeny, George A. (Pittsburgh, PA); Cookson, Alan H. (Churchill Boro, PA)

1981-01-01

359

Effects of shell morphology on mechanics of zebra and quagga mussel locomotion.  

PubMed

Although zebra mussels (Dreissena polymorpha) initially colonized shallow habitats within the North American Great Lakes, quagga mussels (Dreissena bugensis) are becoming dominant in both shallow- and deep-water habitats. Shell morphology differs among zebra, shallow quagga and deep quagga mussels but functional consequences of such differences are unknown. We examined effects of shell morphology on locomotion for the three morphotypes on hard (typical of shallow habitats) and soft (characteristic of deep habitats) sedimentary substrates. We quantified morphology using the polar moment of inertia, a parameter used in calculating kinetic energy that describes shell area distribution and resistance to rotation. We quantified mussel locomotion by determining the ratio of rotational (K(rot)) to translational kinetic energy (K(trans)). On hard substrate, K(rot):K(trans) of deep quagga mussels was fourfold greater than for the other morphotypes, indicating greater energy expenditure in rotation relative to translation. On soft substrate, K(rot):K(trans) of deep quagga mussels was approximately one-third of that on hard substrate, indicating lower energy expenditure in rotation on soft substrate. Overall, our study demonstrates that shell morphology correlates with differences in locomotion (i.e. K(rot):K(trans)) among morphotypes. Although deep quagga mussels were similar to zebra and shallow quagga mussels in terms of energy expenditure on sedimentary substrate, their morphology was energetically maladaptive for linear movement on hard substrate. As quagga mussels can possess two distinct morphotypes (i.e. shallow and deep morphs), they might more effectively utilize a broader range of substrates than zebra mussels, potentially enhancing their ability to colonize a wider range of habitats. PMID:21653816

Peyer, Suzanne M; Hermanson, John C; Lee, Carol Eunmi

2011-07-01

360

The distribution of microborings in molluscan shells from recent reef environments at Lee Stocking Island, Bahamas  

Microsoft Academic Search

Summary  The distribution of microbial borings in bivalve shells was assessed between five research sites in windward and leeward environments\\u000a at the Lee Stocking Island, Bahamas. The research sites are on windward coral reefs (sites B at 2 m, Fat 12 m, and C at 30\\u000a m), a tidal channel stromatolite reef (site A at 5 m), and a leeward hard

Gudrun Radtke

1993-01-01

361

Poloidal rotation velocities in the outer half of Alcator- C plasmas  

SciTech Connect

Poloidal rotation velocities in the outer half of ohmically heated Alcator-{ital C} plasmas have been determined from the Doppler shift of impurity emission lines. The measurements were made using a high-resolution photon-counting detector, sensitive to wavelengths from {similar to}1200 to {similar to}2000 {Angstrom}, mounted in the exit plane of a 1-m Ebert-Fastie spectrometer. The following transitions were used: 2{ital s}2{ital p}{sup 1}{ital P}{sup 0}{sub 1}--2{ital p}{sup 2} {sup 1}D{sub 2} at 1371.292 {Angstrom} in O V, 2{ital s} {sup 2}{ital S}{sub 1/2}--2{ital p}{sup 2}{ital P}{sup 0}{sub 1/2} at 1242.804 {Angstrom} in N V (both of which exist near the limiter radius in Alcator-{ital C}), and 1{ital s}2{ital s} {sup 3}S{sub 1}--1{ital s}2{ital p} {sup 3}P{degree}{sub 2} at 1623.63 {Angstrom} in O VII (which exists at {ital r}/{ital a}{similar to}0.8). The measured rotation velocities are 4--5{times}10{sup 5} cm/s in the direction of the electron diamagnetic drift at the radius of the O V emission shell and {similar to}6{times}10{sup 5} cm/s at the radius of the O VII emission shell, again in the electron diamagnetic drift direction. Therefore poloidal rotation of the outer half of the Alcator-{ital C} plasma with a velocity of several times 10{sup 5} cm/s in the direction of the electron diamagnetic drift is firmly established by these measurements.

Benjamin, R.D.; Terry, J.L.; Moos, H.W. (Department of Physics and Astronomy The Johns Hopkins University, Baltimore, Maryland 21218 (USA))

1990-01-15

362

Photon bremsstrahlung and diffusive broadening of a hard jet  

SciTech Connect

The photon bremsstrahlung rate from a quark jet produced in deep-inelastic scattering (DIS) off a large nucleus is studied in the collinear limit. The leading medium-enhanced higher twist corrections that describe the multiple scattering of the jet in the nucleus are re-summed to all orders of twist. The propagation of the jet in the absence of further radiative energy loss is shown to be governed by a transverse momentum diffusion equation. We compute the final photon spectrum in the limit of soft photons, taking into account the leading and next-to-leading terms in the photon momentum fraction y. In this limit, the photon spectrum in a physical gauge is shown to arise from two interfering sources: one where the initial hard scattering produces an off-shell quark, which immediately radiates the photon and then undergoes subsequent soft rescattering, and an alternative in which the quark is produced on-shell and propagates through the medium until it is driven off-shell by rescattering and radiates the photon. Our result has a simple formal structure as a product of the photon splitting function, the quark transverse momentum distribution coming from a diffusion equation, and a dimensionless factor that encodes the effect of the interferences encountered by the propagating quark over the length of the medium. The destructive nature of such interferences in the small-y limit is responsible for the origin of the Landau-Pomeranchuck-Migdal (LPM) effect. Along the way we also discuss possible implications for quark jets in hot nuclear matter.

Majumder, A.; Mueller, B. [Department of Physics, Duke University, Durham, North Carolina 27708 (United States); Fries, R. J. [Cyclotron Institute and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); RIKEN/BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2008-06-15

363

Prevalence of anisotropic shell growth in rare earth core-shell upconversion nanocrystals.  

PubMed

Through a series of carefully executed experiments, we discovered the prevalence of anisotropic shell growth in many upconversion NaREF4 systems caused by a combination of factors: selective adsorption of ligands on the core surface due to the core crystal structure, ligand etching, and the lattice mismatch between core and shell components. This could lead to incomplete shell formation in core-shell nanocrystals under certain conditions. Shell growth is always faster in the a and b crystallographic directions than in the c direction. In the case of a larger lattice mismatch between the core and shell, shell growth only occurs in the a and b directions resulting in an oblong core-shell structure. These findings are useful for rationalizing shell-dependent emission properties, understanding the emission mechanisms in complex core-shell nanostructures, and for creating accurate models of core-shell designs for multifunctionality and optimal performance in applications. PMID:23570424

Zhang, Chao; Lee, Jim Yang

2013-04-15

364

Shell may expand detergent alcohols  

SciTech Connect

Shell Chemical is studying plans to expand detergent alcohols capacity in the US, CW has learned. The company is considering adding capacity for about 80 million lbs/year. If the project is approved, it would be implemented at the company`s Geismar, LA site. Shell will make a final decision on whether to proceed with the project within six months. It has been rumored to be considering a capacity addition as a result of tightening supply of natural and synthetic detergent alcohols.

NONE

1996-10-23

365

Evaluation of absolute hardness: a new approach.  

PubMed

By taking the energy to be a Morse-like function of the number of electrons, E(N) = ?{1 - e(-?(N-?))}(2) - ?, the electronic chemical potential and global hardness values for a set of atoms and some molecules are calculated from the accurate definitions of these two concepts and using the hybrid B3LYP functional and 6-311++G** basis set. By a comparison between the obtained hardnesses and the corresponding experimental values, it is found that the proposed model yields better values for hardnesses with respect to those that are obtained from the other frequently used methods. It is claimed that the difference between the calculated and experimental hardness values may arise from the approximate equation used for the evaluation of experimental hardnesses. Both of the calculated and experimental molecular hardnesses are used to investigate the change of hardness during the course of some exothermic reactions according to the maximum hardness principle (MHP). It is shown that the obtained hardnesses of reactions from the calculated hardnesses (??(calc)) are more successful in predicting the directions of these reactions than those that are evaluated from the experimental hardnesses (??(exp)). PMID:23360416

Noorizadeh, Siamak; Parsa, Hadi

2013-01-29

366

Local hardness equalization: Exploiting the ambiguity  

NASA Astrophysics Data System (ADS)

In the density-functional theory of chemical reactivity, the local hardness is known to be an ambiguous concept. The mathematical structure associated with this problematic situation is elaborated and three common definitions for the local hardness are critically examined: the frontier local hardness [S. K. Ghosh, Chem. Phys. Lett. 172, 77 (1990)], the total local hardness [S. K. Ghosh and M. Berkowitz, J. Chem. Phys. 83, 2976 (1985)], and the unconstrained local hardness [P. W. Ayers and R. G. Parr, J. Am. Chem. Soc. 122, 2010 (2000)]. The frontier local hardness has particularly nice properties: (a) it has smaller norm than most, if not all, other choices of the local hardness and (b) it is ``unbiased'' in an information-theoretic sense. For the ground electronic state of a molecular system, the frontier local hardness is equal to the global hardness. For an electronic system in its ground state, both the chemical potential and the frontier local hardness are equalized. The frontier local hardness equalization principle provides a computational approach for designing reagents with desirable chemical reactivity profiles.

Ayers, Paul W.; Parr, Robert G.

2008-05-01

367

Bi-functional RuO2-Co3O4 core-shell nanofibers as a multi-component one-dimensional water oxidation catalyst.  

PubMed

The core-shell structure of RuO2-Co3O4 fibers comprising the inner region of highly conductive RuO2 and the outer region of catalytic Co3O4 provided a fast and effective transport pathway for holes to O2-evolving sites, leading to a highly efficient water oxidation performance. PMID:23928721

Ko, Jong Wan; Ryu, Won-Hee; Kim, Il-Doo; Park, Chan Beum

2013-09-26

368

Off-shell nilpotency for on-shell reducibility  

SciTech Connect

In this paper the direct way of Lagrangian BRS gauge-fixing the authors proposed recently is applied to reducible gauge theories: antisymmetric tensor gauge theories are considered as definite examples. It enables us to do without ad hoc ghosts for ghosts. It also achieves BRS-exact forms of full gauge-fixing terms by means of off-shell nilpotent BRS transformations.

Izawa, K.I. (Kyoto Univ. (Japan). Dept. of Physics)

1992-10-20

369

Hard sphere gas state equation  

NASA Astrophysics Data System (ADS)

The dynamic evolution of a gas of N hard spheres determines the equation of state once the equilibrium is reached, after a short transient. The system is investigated in the thermodynamic limit. The algorithms based on a tricky management of the collisions list allow to simulate up to N=10 spheres, rendering the statistical error sufficiently small in simulations involving 10 collisions. The effect of boundaries is discussed, and, to avoid any dependence, periodic boundary conditions are chosen in a box, whose edge is much larger than the spheres radius. The initial state is the symmetric close packing and, by reducing the hard spheres radius, we follow the evolution of the mean free path as a function of the density y (where y is the ratio between the volume of the spheres and the total volume). We observe the solid-fluid first-order phase transition and follow the fluid branch until the hard spheres gas is very dilute. The phase transition is well resolved due to the improved statistics and to the choice, as order parameter, of the mean free path rather than Z=PV/NkT, which has a singularity at zero mean free path. The equations of state in the fluid and solid branches are compared with the Taylor series for the mean free path, obtained from the virial expansions of Z. The second-order truncations P2(y), appear to provide the best fit to the mean free path. This suggests an approximation to Z as Z=1+B2y/P2(y), where B2 is the second virial coefficient.

Rambaldi, Sandro; Salustri, Giovanna; Benedetti, Carlo

2006-02-01

370

The Hard Problem of Cooperation  

PubMed Central

Based on individual variation in cooperative inclinations, we define the “hard problem of cooperation” as that of achieving high levels of cooperation in a group of non-cooperative types. Can the hard problem be solved by institutions with monitoring and sanctions? In a laboratory experiment we find that the answer is affirmative if the institution is imposed on the group but negative if development of the institution is left to the group to vote on. In the experiment, participants were divided into groups of either cooperative types or non-cooperative types depending on their behavior in a public goods game. In these homogeneous groups they repeatedly played a public goods game regulated by an institution that incorporated several of the key properties identified by Ostrom: operational rules, monitoring, rewards, punishments, and (in one condition) change of rules. When change of rules was not possible and punishments were set to be high, groups of both types generally abided by operational rules demanding high contributions to the common good, and thereby achieved high levels of payoffs. Under less severe rules, both types of groups did worse but non-cooperative types did worst. Thus, non-cooperative groups profited the most from being governed by an institution demanding high contributions and employing high punishments. Nevertheless, in a condition where change of rules through voting was made possible, development of the institution in this direction was more often voted down in groups of non-cooperative types. We discuss the relevance of the hard problem and fit our results into a bigger picture of institutional and individual determinants of cooperative behavior.

Eriksson, Kimmo; Strimling, Pontus

2012-01-01

371

Biogenesis of outer membranes in Gram-negative bacteria.  

PubMed

The outer membrane, an essential organelle of Gram-negative bacteria, is composed of four major components: lipopolysaccharide, phospholipids, beta-barrel proteins, and lipoproteins. The mechanisms underlying the transport of these components to outer membranes are currently under extensive examination. Among them, the sorting of lipoproteins to the outer membrane of Escherichia coli has been clarified in detail. The Lol system, composed of five proteins, catalyzes outer membrane sorting of lipoproteins. Various Lpt proteins have recently been identified as factors involved in the transport of lipopolysaccharide to the outer membrane, although the mechanism remains largely unknown. Proteins with alpha-helical membrane spanning segments are found in the inner membrane, whereas amphipathic beta-barrel proteins span the outer membrane. These beta-barrel proteins are inserted into the outer membranes through a central core protein BamA (YaeT) with the help of four outer membrane lipoproteins. In contrast, little is known about how phospholipids are transported to the outer membrane. PMID:19270402

Tokuda, Hajime

2009-03-07

372

Recommended Exploration Strategy for the Outer Planets 2013-2022: Goals and Priorities  

NASA Astrophysics Data System (ADS)

Important scientific discoveries continue to be made in the outer solar system through NASA missions and research programs (for example, via the ongoing Cassini mission at Saturn, the New Horizons encounter with Jupiter in 2007, and earth-based studies of Uranus and Neptune). The Outer Planets Assessment Group (OPAG) was established by NASA to identify scientific priorities and pathways for outer solar system exploration, because the outer solar system provides critical clues to unraveling the mysteries of how solar systems form and evolve, how planetary systems become habitable, and how life has evolved in our solar system. Addressing such scientific questions requires a balanced strategy of outer solar system exploration that includes steady support for vigorous programs of basic research, data analysis, and technology development. Fundamental new discoveries are best made with a mixture of mission sizes that includes large (flagship) missions, along with medium-sized and smaller-sized (as practical) missions. Such a strategy is most efficiently implemented as a coherent Outer Planets Exploration Program. Missions to the outer solar system are major undertakings, requiring large and expensive launch vehicles, long mission durations, highly reliable (frequently radiation hard) and autonomous spacecraft, and radioisotope power sources in most cases. OPAG recommends that the Decadal Survey explore the possibilities for a program structure/categorization that could allow ‘small flagship’ class missions to be considered, providing a greater range of choice and capabilities in the mix to balance program size and science return. With the Galileo mission concluded, the Cassini equinox mission in progress, and Juno in development, OPAG strongly endorses the competitive selection by NASA of the Jupiter Europa Orbiter (JEO) as the next Outer Planets Flagship and as part of the Europa Jupiter System Mission (EJSM) with ESA, a collaboration that includes a Ganymede orbiter and an increased focus on Jupiter science; OPAG strongly recommends support of JEO and EJSM in the Decadal Survey. In addition, OPAG strongly endorses approval by NASA of the Cassini Solstice Mission, including the Juno-like end-of-mission scenario, given the likely phenomenal return on investment. OPAG also advocates the need for a focused technology program for the next Outer Planet Flagship Mission after EJSM, in order to be ready for a launch in the mid-2020s. In this regard, a return to Titan and Enceladus is the highest priority. Technologies that require long-term investment for missions beyond the next decade should also be considered. New Frontiers class missions that should be considered in the interim include (but not in priority order) probe missions to the giant planets, an Io observer, a Neptune/Triton/KBO rendezvous, and a Titan in-situ explorer or probe, and OPAG recommends that these be studied, costed, and added the approved New Frontiers mission set.

McKinnon, W. B.; Johnson, T. V.

2009-12-01

373

Crystallization of hard aspherical particles  

NASA Astrophysics Data System (ADS)

We use numerical simulations to study the crystallization of monodisperse systems of hard aspherical particles. We find that particle shape and crystallizability can be easily related to each other when particles are characterized in terms of two simple and experimentally accessible order parameters: one based on the particle surface-to-volume ratio and the other on the angular distribution of the perturbations away from the ideal spherical shape. We present a phase diagram obtained by exploring the crystallizability of 487 different particle shapes across the two-order-parameter spectrum. Finally, we consider the physical properties of the crystalline structures accessible to aspherical particles and discuss limits and relevance of our results.

Miller, William L.; Bozorgui, Behnaz; Cacciuto, Angelo

2010-04-01

374

Dual shell pressure balanced vessel  

DOEpatents

A dual-wall pressure balanced vessel for processing high viscosity slurries at high temperatures and pressures having an outer pressure vessel and an inner vessel with an annular space between the vessels pressurized at a pressure slightly less than or equivalent to the pressure within the inner vessel.

Fassbender, Alexander G. (West Richland, WA)

1992-01-01

375

Acinetobacter baumannii outer membrane protein A modulates the biogenesis of outer membrane vesicles.  

PubMed

Acinetobacter baumannii secretes outer membrane vesicles (OMVs) during both in vitro and in vivo growth, but the biogenesis mechanism by which A. baumannii produces OMVs remains undefined. Outer membrane protein A of A. baumannii (AbOmpA) is a major protein in the outer membrane and the C-terminus of AbOmpA interacts with diaminopimelate of peptidoglycan. This study investigated the role of AbOmpA in the biogenesis of A. baumannii OMVs. Quantitative and qualitative approaches were used to analyze OMV biogenesis in A. baumannii ATCC 19606T and an isogenic ?AbOmpA mutant. OMV production was significantly increased in the ?AbOmpA mutant compared to wild-type bacteria as demonstrated by quantitation of proteins and lipopolysaccharides (LPS) packaged in OMVs. LPS profiles prepared from OMVs from wild-type bacteria and the ?AbOmpA mutant had identical patterns, but proteomic analysis showed different protein constituents in OMVs from wild-type bacteria compared to the ?AbOmpA mutant. In conclusion, AbOmpA influences OMV biogenesis by controlling OMV production and protein composition. PMID:22367951

Moon, Dong Chan; Choi, Chul Hee; Lee, Jung Hwa; Choi, Chi-Won; Kim, Hye-Yeon; Park, Jeong Soon; Kim, Seung Il; Lee, Je Chul

2012-02-27

376

Refined Triangular Plate and Shell Elements.  

National Technical Information Service (NTIS)

In this work several refinements of small strain triangular plate and shallow shell elements are discussed. These element types are closely connected in the present work, because the shell elements are formulated on the basis of the plate bending elements...

F. van Keulen

1993-01-01

377

Short-Wavelength Perturbation Growth Studies for NIF Double-Shell Ignition Target Designs  

SciTech Connect

A major challenge in achieving ignition with double-shells is controlling the mix of the dense, high-Z pusher into the DT gas. During implosion, interface perturbations become unstable as they are subjected to either impulsive (Richtmyer-Meshkov) or time-dependent (Rayleigh-Taylor) accelerations. These processes are especially critical for double-shells since density gradient stabilization mechanisms (that play a key role in the baseline cryogenic target) are not present. To study the nonlinear RT evolution for such a large range in modes we use the parallel 3-D rad-hydro code HYDRA. Simulations have revealed a new pathway for the RT instability of perturbations on the outer surface of the inner shell leading to shell disruption. We demonstrate that this instability can be controlled by tamping the inner shell with a low-Z material but it is not entirely suppressed. We find that the pusher/tamper interface transitions to turbulence at late times with large Reynolds number but still the integrity of the pusher is maintained. Furthermore, numerical studies suggest that for perturbations with mode numbers (l > 600), the mix-width at the pushed tamper interface approaches a constant value. Finally, to avoid turbulence onset altogether we investigate a new pusher with an imprinted density-gradient scale length in combination with a CuO/Cu{sub 2}O foam. Preliminary 2-D simulations with mode numbers up tp l = 612 show virtually no growth in this design.

Milovich, J L; Amendt, P; Marinak, M; Robey, H

2003-08-22

378

Outer-zone electron precipitation produced by a vlf transmitter. Technical report  

SciTech Connect

Using high-resolution pitch-angle measurements made by a magnetic-focusing electron spectrometer on the S3-3 satellite while in the drift-loss-cone region of the magnetosphere, characteristics of fluxes of 108 to 654-keV electrons precipitated in the inner zone, in the slot region, and in the outer zone of the magnetosphere are all shown to be consistent with the precipitation having been produced by the same ground-based VLF transmitter, UMS. Pitch angle measurements are used to locate the longitude of precipitation. The temporal pattern of transmitter operation obtained from synoptic data from a ground-based VLF receiver is used along with drift-rate calculations to predict the electron energies as a function of L-shell which should be observable by the S3-3 instrument. The predicted energy response is then compared with the in-situ observations, getting complete agreement. Finally, wave-particle resonance calculations are made for each of the three regions. The study indicates that ground-based VLF transmitters, which have previously been shown to produce precipitation in the inner zone and slot regions, are almost certainly instrumental in precipitating electrons in the outer zone also.

Vampola, A.L.; Adams, C.D.

1988-03-01

379

Are Short GRBs Really Hard?  

SciTech Connect

Thanks to the rapid position notice and response by HETE-2 and Swift, the X-ray afterglow emissions have been found for four recent short gamma-ray bursts (GRBs; GRB 050509b, GRB 050709, GRB 050724, and GRB 050813). The positions of three out of four short GRBs are coincident with galaxies with no current or recent star formation. This discovery tightens the case for a different origin for short and long GRBs. On the other hand, from the prompt emission point of view, a short GRB shows a harder spectrum comparing to that of the long duration GRBs according to the BATSE observations. We investigate the prompt emission properties of four short GRBs observed by Swift/BAT. We found that the hardness of all four BAT short GRBs is in between the BATSE range for short and long GRBs. We will discuss the spectral properties of short GRBs including the short GRB sample of Konus-Wind and HETE-2 to understand the hard nature of the BATSE short GRBs.

Sakamoto, T.; Cummings, J. [NASA Goddard Space Flight Center (United States); Barbier, L.; Barthelmy, S.; Gehrels, N.; Parsons, A.; Tueller, J.; Cline, T. [NASA Goddard Space Flight Center (United States); Fenimore, E.; Palmer, D. [Los Alamos National Laboratory (United States); Hullinger, D. [NASA Goddard Space Flight Center (United States); University of Maryland (United States); Krimm, H.; Markwardt, C. [NASA Goddard Space Flight Center (United States); Sato, G. [Institute of Space and Astronautical Science (United States); Aptekar, R.; Golenetskii, S.; Mazets, E.; Pal'shin, V. [Ioffe Physico-Technical Institute (Russian Federation); Ricker, G. [Massachusetts Institute of Technology (United States); Lamb, D. [University of Chicago (United States)] (and others)

2006-05-19

380

Stellar populations in shell galaxies  

NASA Astrophysics Data System (ADS)

UBV surface photometry of the shell galaxies Arp 230, NGC 7010, and Arp 223 is presented and all are found to be the result of mergers. In Arp 230. the merger of two spirals induced a burst of star formation which has declined in strength since the collision. The remnant seems likely to become elliptical. NGC 7010 has very red shells, perhaps redder than the galaxy itself. Evolution of the stellar content of these shells may be important. Arp 223 has shell colors which are slightly bluer than the main body of the galaxy, consistent with an origin in an Sb. Data indicate that the timescale since the interaction is typically approximately equal to 1 Gyr. Moreover, those ellipticals that have been formed by mergers should have complex stellar populations with a component formed in the collision. This extra component might be detectable by the methods of empirical population synthesis, at least to some age limit, making it possible to investigate the relative numbers of ellipticals formed in this manner by methods other than morphology.

McGaugh, Stacy S.; Bothun, Gregory D.

1990-10-01

381

Whiteand Brown-shelled Eggs  

Microsoft Academic Search

BIRDS which lay their eggs in comparatively unprotected places and in a hollow in the ground, as is the case with the pheasant, partridge, jungle fowl, &c., always lay coloured eggs closely resembling in tint the colouring of their surroundings. White-shelled eggs are laid only by birds which make a good nest-those which make it in a secluded spot, or

F. L. M

1906-01-01

382

Shell structures for biogas plants  

SciTech Connect

The shell structures designed for biogas plants of the fixed-dome type by the Bremen Overseas Research and Development Association are described. Biogas digesters of the design described have been successfully tested in Rwanda and India without structural or contractural problems.

Sasse, L.

1982-01-01

383

Thermostability of Plates and Shells.  

National Technical Information Service (NTIS)

The monograph is a study of the thermostability of plates and shells which are of great interest for modern engineering. Correct formulations of mechanical problems of thermostability and the methods for their solution are given in it, as well as specific...

P. M. Ogibalov V. F. Gribanov

1971-01-01

384

Time of Formation and Chemical Alteration of Small Icy Objects in the Outer Solar System  

NASA Astrophysics Data System (ADS)

We consider scenarios for the early chronology of outer solar system icy objects (e.g. satellites, dwarf planets) depending on the time at which these objects formed with respect to the production of calcium-aluminum inclusions. Recent models and observations indicate that the outer Solar system could have formed within a few My after the beginning of the Solar system. In such conditions meteorite parent bodies and icy objects (from planetesimals to large icy objects) could have had a similar early history. We investigate conditions that may drive hydrothermal activity in icy planetesimals, and the consequences of such activity for the early history of bigger objects. Early melting can be accompanied by hydrothermal circulation, resulting in aqueous alteration of the silicate interior and redistribution of major elements between the rock and volatile phases, as well as the destabilization of clathrates. These processes could have consequences on the long-term evolution of the larger bodies. For example, salts affect the melting temperature of icy shells and hydrated silicates affect heat transfer through a rocky core. We identify several classes of planetesimals based on size, time of formation, initial rock mass fraction and volatile composition. The smallest ones are not affected by short-lived radioisotope decay. The medium-sized planetesimals (in the 5-20 km range) are affected by partial melting while planetesimals several tens of km in radius could be fully differentiated before they accreted into larger objects. We explore the consequences of the potential diversity of early outer solar system planetesimal composition on the evolution of icy satellites and dwarf planets. Acknowledgements: This work has been conducted at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Copyright 2008 California Institute of Technology. Government sponsorship acknowledged.

Castillo-Rogez, Julie; Haw, M.; Vance, S.; Matson, D.; Johnson, T.

2008-09-01

385

Thin-shell wormholes in dilaton gravity  

SciTech Connect

In this work we construct charged thin-shell Lorentzian wormholes in dilaton gravity. The exotic matter required for the construction is localized in the shell and the energy conditions are satisfied outside the shell. The total amount of exotic matter is calculated and its dependence with the parameters of the model is analyzed.

Eiroa, Ernesto F. [Instituto de Astronomia y Fisica del Espacio, C.C. 67, Suc. 28, 1428, Buenos Aires (Argentina); Simeone, Claudio [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pab. I, 1428, Buenos Aires (Argentina)

2005-06-15

386

Asymptotically Correct Shell Model for Nuclear Fission  

Microsoft Academic Search

A two-center shell model with oscillator potentials, l-->.s--> forces, and l-->2 terms is developed. The shell structures of the original spherical nucleus and those of the final fragments are reproduced. For small separation of the two centers the level structure resembles the Nilsson scheme. This two-center shell model might be of importance in problems of nuclear fission.

D. Scharnweber; U. Mosel; W. Greiner

1970-01-01

387

Molecular hardness and softness, local hardness and softness, hardness and softness kernels, and relations among these quantities  

Microsoft Academic Search

Hardness and softness kernels &eegr;(r,r’) and s(r,r’) are defined for the ground state of an atomic or molecular electronic system, and the previously defined local hardness and softness &eegr;(r) and s(r) and global hardness and softness &eegr; and S are obtained from them. The physical meaning of s(r), as a charge capacitance, is discussed (following Huheey and Politzer), and two

Max Berkowitz; Robert G. Parr

1988-01-01

388

Testing and analysis to determine the shell thickness required to prevent puncture  

SciTech Connect

Type B radioactive material packages are required to withstand a hypothetical puncture accident of a free fall from a height of one meter onto a 15 cm diameter mild steel puncture probe. For many packages it is desirable to have this accident event not result in puncture or tearing of the outer shell of the package. The wall thickness necessary to prevent this has historically been determined by test or the use of empirical relations. This technique generally results in overly conservative designs, but the degree of conservatism is uncertain. The use of modem finite element codes to determine package response to puncture accidents can result in designs that are both safe and economical. The work reported in this paper is aimed at developing a method to analytically determine the wall thickness required to prevent puncture. For designers and regulators to have confidence in this analytical method, however, it must be benchmarked against test results. A series of tests has been conducted with differing shell thicknesses, shell materials of mild steel and stainless steel, and shell backing materials of lead, foam, and air. The results of these tests have been compared with pre-test analytical predictions of the response obtained from the nonlinear transient dynamic finite element program PRONTO-2D. From this comparison it can be seen that the finite element method can accurately predict the response of packages to puncture accidents. This implies that an analytical technique based on the finite element method can be used to design packages having known response and margin of safety against tearing of the outer shell. In addition, the analytical technique can accurately predict the deformed shape of the package following the test. This may be important for subsequent calculations, such as external dose and heat input during a thermal event.

Ammerman, D.J.; Radloff, H.D.; Eifert, E.J.

1998-05-01

389

Insights from multiple structures of the shell proteins from the [beta]-carboxysome  

SciTech Connect

Carboxysomes are primitive bacterial organelles that function as a part of a carbon concentrating mechanism (CCM) under conditions where inorganic carbon is limiting. The carboxysome enhances the efficiency of cellular carbon fixation by encapsulating together carbonic anhydrase and the CO{sub 2}-fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). The carboxysome has a roughly icosahedral shape with an outer shell between 800 and 1500 {angstrom} in diameter, which is constructed from a few thousand small protein subunits. In the cyanobacterium Synechocystis sp. PCC 6803, the previous structure determination of two homologous shell protein subunits, CcmK2 and CcmK4, elucidated how the outer shell is formed by the tight packing of CcmK hexamers into a molecular layer. Here we describe the crystal structure of the hexameric shell protein CcmK1, along with structures of mutants of both CcmK1 and CcmK2 lacking their sometimes flexible C-terminal tails. Variations in the way hexamers pack into layers are noted, while sulfate ions bound in pores through the layer provide further support for the hypothesis that the pores serve for transport of substrates and products into and out of the carboxysome. One of the new structures provides a high-resolution (1.3 {angstrom}) framework for subsequent computational studies of molecular transport through the pores. Crystal and solution studies of the C-terminal deletion mutants demonstrate the tendency of the terminal segments to participate in protein-protein interactions, thereby providing a clue as to which side of the molecular layer of hexameric shell proteins is likely to face toward the carboxysome interior.

Tanaka, S.; Sawaya, M.R.; Phillips, M.; Yeates, T.O.; (UCLA)

2009-03-02

390

Estimation of calcified tissues hardness via calcium and magnesium ionic to atomic line intensity ratio in laser induced breakdown spectra  

NASA Astrophysics Data System (ADS)

Calcified tissues representing three different matrices, namely enamel of human teeth, shells and eggshell, have been studied via Laser Induced Breakdown Spectroscopy (LIBS) technique. The experimental CaII/CaI and MgII/MgI ratios have been measured, in view of the expected correlation between the extent of ionization caused by the laser induced shock wave (SW) and the hardness of the target. The ratio CaII/CaI between the ionic calcium line at 373.69 nm and the neutral line at 428.9 nm is obtained for enamel, shells and eggshell spectra, as well as the ratio MgII/MgI between the ionic magnesium line at 280.26 nm and the neutral line at 285.22 nm. The results show that such spectral lines intensities ratio differs for different matrices and is indeed related to the target materials hardness. It is also found that the MgII/MgI ratio is preferable as an indicator of hardness since these lines are less affected by self absorption. The SW front speed has been measured in the three cases and the obtained values confirm the proportionality to the target hardness. The results here obtained suggest the feasibility of the quantitative estimation of hardness for any other calcified tissues.

Abdel-Salam, Z. A.; Galmed, A. H.; Tognoni, E.; Harith, M. A.

2007-12-01

391

Extensions to a nonlinear finite-element axisymmetric shell model based on Reissner's shell theory  

SciTech Connect

Extensions to shell analysis not usually associated with shell theory are described in this paper. These extensions involve thick shells, nonlinear materials, a linear normal stress approximation, and a changing shell thickness. A finite element shell-of-revolution model has been developed to analyze nuclear material shipping containers under severe impact conditions. To establish the limits for this shell model, the basic assumptions used in its development were studied; these are listed in this paper. Several extensions were evident from the study of these limits: a thick shell, a plastic hinge, and a linear normal stress.

Cook, W.A.

1981-01-01

392

Outer magnetospheric structure: Jupiter and Saturn compared  

NASA Astrophysics Data System (ADS)

The Jovian dayside magnetosphere is traditionally divided into three different regions with the outermost region, colloquially referred to as the cushion region, existing between the outer edge of the magnetodisk and the magnetopause. Magnetometer and plasma data from 6 different spacecraft are used to determine the average properties of this region, including its characteristic thickness at the subsolar point, and these observations are compared with data from the Saturnian magnetosphere obtained using the Pioneer, Voyager, and Cassini spacecraft. Significant differences are found in the structure of the two rotationally driven magnetospheres with the Saturnian system showing little evidence for the cushion region seen at Jupiter. These differences are discussed in terms of the parameter regimes pertinent to each planet, and the potential effect of magnetodisk warping at Saturn is discussed. It is tentatively suggested that while the Jovian magnetodisk typically breaks down several tens of planetary radii inside the magnetopause, thus allowing plasma-depleted flux tubes beyond it to relax into the cushion region configuration, the Saturnian magnetodisk may persist until much closer to the magnetospheric boundary. A number of observational tests of this hypothesis are proposed, and the need for improved observations at both planets is stressed.

Went, D. R.; Kivelson, M. G.; Achilleos, N.; Arridge, C. S.; Dougherty, M. K.

2011-04-01

393

Ion anisotropies in the outer Jovian magnetosphere  

SciTech Connect

We present results from the Voyager 1 and 2 low-energy charged particle measurement of ion anisotropies in the outer Jovian magnetosphere (R> or approx. =20 R/sub J/). Theses anisotropies represent the first observed from an instrument rotating in the spin plane of Jupiter. For the several ion species ivestigated the first-order anisotropies are all strongly in the corotational sense throughout most of the Jovian magnestophere and out to the magnetopause on the dayside. There is some evidence for a small component of outward flow in the corotating region. Beyond approx.130--150 R/sub J/ along the Voyager outbound trajectories the anisotropies indicate a magnetospheric wind flowing outward from Jupiter. The change corotational to tailward flow on the nightside occurs well inside the magnetopause. The anisotropy amplitudes increase linearly with radial distance and, in the disc regions, decrease with distance from the magnetodisc mid-plane. In one case examined in detail using separtely identified H, He, and O/S ions the convection speed at 58 R/sub J/ is found to agree with the corotation speed (..cap omega..R) to within approx.3%. A linear Compton-Getting analysis reveals that the convective speeds in the dayside magnetosphere are in agreement with rigid corotation whenever the plasma flow direction is approximately in the corotation sense, while at other times the convection speeds are substantially less than corotation.

Carbary, J.F.; Krimigis, S.M.; Keath, E.P.; Gloeckler, G.; Axford, W.I.; Armstrong, T.P.

1981-09-30

394

Meridional plasma flow in the outer heliosphere  

SciTech Connect

Voyager 2 observations made in the outer heliosphere near 25 AU and within 2/sup 0/ of the heliographic equatorial plane show periodic variations in the meridional (North/South) flow velocities that are much more prominent than the East/West variations. An autocorrelation analysis shows that the flow variation has an approx.25.5 day period in the latter half of 1986, in approximate agreement with the solar rotation period. The turning of the flow from northward to southward is often accompanied by abrupt increases in solar wind speed and pressure consistent with changes expected at forward shocks, suggesting origins of non-radial flow in stream dynamics. Approximately 80/sup 0/ of the time, the magnetic field data indicate that the northward flow is seen when Voyager is above the current sheet and southward flow when it is below, but the transitions from northward to southward and vice versa do not occur at the crossings of the current sheet. Thus increased pressure in interaction regions remains the best candidate for the driver of the non-radial flows. copyright American Geophysical Union 1988

Lazarus, A.J.; Yedidia, B.; Villanueva, L.; McNutt R.L. Jr.; Belcher, J.W.; Villante, U.; Burlaga, L.F.

1988-12-01

395

Laboratory models of the Earth's outer core  

NASA Astrophysics Data System (ADS)

We construct liquid sodium experiments as models of the Earth's core. Key to understanding these several experimental devices is knowing how turbulence is effected by rotation and magnetic fields. In the approach to the planetary regeme, several remarkable behaviors appear [1]. As rotation and magnetic fields add some measure of elasticity to the flows, several types of driven planetary modes are observed depending on the force balances involved. Ordering the Coriolis, Lorentz, and inertial forces is key to understanding the complicated states observed. While these experiments are undertaken in part to understand the geodynamo, they have led to a number of different first observations, including the magneto-rotational instability [2] and inertial waves in spherical Couette flow. These different approaches to using laboratory experiments are opening up a new direction to understanding the dynamics of the Earth's outer core, other Planetary interiors, and a host of astrophysical objects. [1] W.L. Shew and D.P. Lathrop, ``Liquid sodium model of geophysical core convection,'' Phys. Earth and Planetary Interiors, 153, 136-149 (2005). [2] D.R. Sisan, N. Mujica, W.A. Tillotson, Y.-M. Huang, W.Dorland, A.B. Hassam, T.M. Antonsen, and D.P. Lathrop, ``Experimental Observation and Characterization of the Magnetorotational Instability,'' Phys. Rev. Lett. 93, 114502 (2004).

Lathrop, Daniel

2007-03-01

396

Ultraviolet Extinction in the Outer Galaxy  

NASA Astrophysics Data System (ADS)

We propose to test whether the empirical trend of increasing far-ultraviolet extinction and decreasing 2200 A bump strength with decreasing metallicity seen among the solar neighborhood, LMC, and SMC is also valid within the Milky Way. Recent re-examinations of the average extinction curve in the LMC suggest that the dependence may not be as strong as originally thought; stars outside of the atypical 30 Doradus region exhibit extinction remarkably similar to that of diffuse regions in the Milky Way. To test the validity of the trend requires observations of the extinction in other systems of different metallicities. Long exposure IUE spectra of luminous stars in M31 and M33 have been used to estimate the extinction in these galaxies but the low flux levels and uncertainties of the true stellar intrinsic colors make the results susceptible to large errors. To study extinction in systems of low metal content does not require observations of extragalactic stars, however. With the galactic abundance gradient, a metallicity comparable to that in the LMC is reached in only three or four kiloparsecs from the solar circle. We intend to measure the extinction curves toward several stars at this distance or beyond. The low nearby extinction toward much of the outer Galaxy ensures that the extinction of the stars is dominated by distant dust. The use of relatively bright and nearby stars will allow us to measure the extinction in an unexplored metal poor environment with unusually high precision.

Bohm-Vitense, Erika

397

The Outer Heliosphere: The Next Frontiers  

NASA Astrophysics Data System (ADS)

The 11th COSPAR Colloquium "The Outer Heliosphere: The Next Frontiers" was held in Potsdam, Germany, from July 24 to 28, 2000, and is the second dedicated to this subject after the first one held in Warsaw, Poland in 1989. Roughly a century has passed after the first ideas by Oliver Lodge, George Francis Fitzgerald and Kristan Birkeland about particle clouds emanating from the Sun and interacting with the Earth environment. Only a few decades after the formulation of the concepts of a continuous solar corpuscular radiation by Ludwig Bierman and a solar wind by Eugene Parker, heliospheric physics has evolved into an important branch of astrophysical research. Numerous spacecraft missions have increased the knowledge about the heliosphere tremendously. Now, at the beginning of a new millenium it seems possible, by newly developed propulasion technologies to send a spacecraft beyond the boundaries of the heliosphere. Such an Interstellar Proce will start the in-situ exploration of interstellar space and, thus, can be considered as the first true astrophysical spacecraft. The year 2000 appeared to be a highly welcome occassion to review the achievements since the last COSPAR Colloquia 11 years ago, to summarize the present developments and to give new impulse for future activities in heliospheric research.

Scherer, K.; Fichtner, Horst; Fahr, Hans Jörg; Marsch, Eckart

398

The Outer Heliosphere: The Next Frontier  

NASA Astrophysics Data System (ADS)

Only a few decades after the formulation of the concept of a continuous solar corpus- cular radiation by Ludwig Biermann and a solar wind by Eugene Parker, heliospheric physics has evolved into an important branch of astrophysical research. The solar wind forms a bubble, called the heliosphere, in the local interstellar medium, within which the solar system resides and whose size and properties are determined by the manner in which the solar wind and the partially ionized local interstellar medium are coupled. In the last decade, great progress has been made in our understanding of the physical processes thought to describe the outer heliosphere. Numerous spacecraft missions have increased our knowledge about the large-scale structure, the properties, and the character of the heliosphere tremendously. of these, the ageing spacecraft Voyager 1,2 might encounter the inner border of the heliospheric boundary region in the not too distant future. Now, at the beginning of a new millenium, it seems possible, by newly developed technologies to send an interstellar probe beyond the boundaries of the he- liosphere, in order to explore the local interstellar medium in situ. We shall review our basic understanding of global heliospheric structure, emphasizing the importance of the LISM-solar wind coupling, emphasizing the demands and constraints that this places on a mission to the edge of interstellar space.

Heber, B.; Zank, G. P.

399

Bathymetry and acoustic backscatter-outer mainland shelf, eastern Santa Barbara Channel, California  

USGS Publications Warehouse

In 2010 and 2011, scientists from the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC), acquired bathymetry and acoustic-backscatter data from the outer shelf region of the eastern Santa Barbara Channel, California. These surveys were conducted in cooperation with the Bureau of Ocean Energy Management (BOEM). BOEM is interested in maps of hard-bottom substrates, particularly natural outcrops that support reef communities in areas near oil and gas extraction activity. The surveys were conducted using the USGS R/V Parke Snavely, outfitted with an interferometric sidescan sonar for swath mapping and real-time kinematic navigation equipment. This report provides the bathymetry and backscatter data acquired during these surveys in several formats, a summary of the mapping mission, maps of bathymetry and backscatter, and Federal Geographic Data Committee (FGDC) metadata.

Dartnell, Peter; Finlayson, David P.; Ritchie, Andrew C.; Cochrane, Guy R.; Erdey, Mercedes D.

2012-01-01

400

Newborns' Face Recognition: Role of Inner and Outer Facial Features  

ERIC Educational Resources Information Center

|Existing data indicate that newborns are able to recognize individual faces, but little is known about what perceptual cues drive this ability. The current study showed that either the inner or outer features of the face can act as sufficient cues for newborns' face recognition (Experiment 1), but the outer part of the face enjoys an advantage…

Turati, Chiara; Macchi Cassia, Viola; Simion, Francesca; Leo, Irene

2006-01-01

401

Outer Continental Shelf oil pipelines under the Interstate Commerce Act  

Microsoft Academic Search

Since Congress did not repeal the Interstate Commerce Act (ICA) when it enacted the Outer Continental Shelf Lands Act of 1953, it is necessary to examine the jurisdictional provisions of the ICA to determine whether particular oil pipelines on the Outer Continental Shelf (OCS) are subject to ICA regulation. Certain pipeline operations will fall outside the scope of the ICA

Malet

1983-01-01

402

Identification of Major Outer Surface Proteins of Streptococcus agalactiae  

Microsoft Academic Search

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 electro- phoresis. 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.

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

2002-01-01

403

Lambda encodes an outer membrane protein: The lom gene  

Microsoft Academic Search

? infected minicells synthesize a polypeptide (Mr=20,500) which is incorporated almost exclusively into the outer membrane of the minicell envelope. The gene (lom=lambda outer membrane) encoding this polypeptide has been mapped in the nonessential region of the ? genome between coordinates 39.4% and 40.7% of ?.

John N. Reeve; Jocelyn E. Shaw

1979-01-01

404

Radio and plasma waves at the outer planets  

Microsoft Academic Search

We review our present knowledge of plasma waves and non-thermal radio emissions at the outer planets. The review mainly concerns waves linked to electron dynamics. After a summary of the basics of radio and plasma wave modes as derived from the theory and from observations in the Earth's vicinity, we discuss the counterpart of these waves as observed in outer

P. Zarka

2004-01-01

405

Outer Space Arms Control: Existing Regime and Future Prospects  

Microsoft Academic Search

The existing arms control regime for outer space bans attacks on satellites of other countries, except as acts of self-defense. The moon and other celestial bodies cannot be used for military activities. Detonating nuclear explosives in outer space is prohibited. Deployment in space of nuclear weapons or other weapons of mass destruction is prohibited. Development, testing, or deployment of space-based

Norman A Wulf

1985-01-01

406

Polarization scattering characteristics of chaff cloud in outer space  

Microsoft Academic Search

To meet the increasing need of modern ballistic missile countermeasure, it becomes more and more important to study chaff cloud's scattering characteristics in outer space more accurately. A coherent scattering model is presented to depict the polarization scattering process of chaff cloud in outer space instead of the traditional noncoherent model. Chaff cloud's polarization scattering matrix and RCS formulae are

Wang Xuesong; Chen Zhijie; Li Yongzhen

2001-01-01

407

Facile synthesis of yolk-shell magnetic mesoporous carbon microspheres for efficient enrichment of low abundance peptides.  

PubMed

Magnetic mesoporous carbon microspheres with a yolk-shell structure (YSMMCS) have been prepared via a new in situ carbon source strategy. The material was fabricated by two shells coated onto the Fe3O4 particles; the inner dense and thick silica shell could protect the magnetic core from harsh acidic solvents as well as induce the void between the core and the outer shell for the yolk-shell structure, while the outer organosilica shell was used as the template and carbon source for in situ preparation of a carbon shell with mesoporous structure. A C18-alkyl chain was incorporated in situ as the carbon precursor efficiently, avoiding the conventional infiltration step, which was very difficult to manipulate and time-consuming with the possibility of losing the carbon precursor. The resulting yolk-shell magnetic mesoporous carbon microspheres exhibited a high surface area (273.15 m(2) g(-1)), a large pore volume (0.31 cm(3) g(-1)), and a strong magnetic response (a saturation magnetization value of 34.57 emu g(-1)). As a result of the void between the core and the outer shell and the ?-? stacking effect, adsorption capacity reached 191.64 mg g(-1) by using Rhodamine B as a standard analyte, indicating the great potential application of the material as drug carriers. Owing to the inherent hydrophobicity and high surface area, the composite material showed better performance in the enrichment of peptides than a magnetic mesoporous silica material (Fe2O3@nSiO2@mSiO2). According to the LC-MS/MS results, about 51 and 29 nonredundant peptides were identified from tryptic digests of 5 nM BSA. Additionally, taking advantage of the mesoporous structure and strong magnetic response, the material was utilized to selectively extract low abundance endogenous peptides from human serum in the presence of high abundance proteins. Based on the LC-MS/MS results, 962 endogenous peptides were obtained by 2.5 mg YSMMCS relative to 539 endogenous peptides by 5 mg Fe2O3@nSiO2@mSiO2, confirming the outstanding performance of YSMMCS in peptidome analysis. PMID:24061763

Wan, Hao; Qin, Hongqiang; Xiong, Zhichao; Zhang, Weibing; Zou, Hanfa

2013-09-23

408

Post-Transgressive and Modern Erosion on the New Jersey Outer Shelf  

NASA Astrophysics Data System (ADS)

Recent erosion is evident on the outer New Jersey shelf (> 50 m water depth) based on analysis of multibeam bathymetry, backscatter, and chirp seismic reflection data, as well as grab samples and short cores. Truncation at the seafloor of the transgressive ravinement surface indicates that erosion occurred in the post-transgressive environment, i.e. after passage of the shoreline and development of the surficial sand sheet that caps the ravinement. Apparently moribund oblique sand ridges are also truncated by large, erosional swales oriented along the primary modern current direction, indicating that erosion likely post dates sand ridge evolution, which is known to persist to water depths of 40 m. Post-transgressive erosion has exposed a variety of strata at the seafloor, including: shallowly buried, fluvial channel systems, formed during or somewhat after the Last Glacial Maximum and filled during the transgression; the outer shelf wedge, likely deposited during falling sea level conditions; and a regional reflector, "R", that likely represents erosion during the last regression , i.e., exposing material >40 kyr. Depths of erosion range from a few meters to >10 m. A "ribbon" seafloor morphology marks much of the eroded regions. Ribbons are observed in the backscatter data as alternating bands of low and high backscatter elongated in the direction of bottom flow. Samples from the high backscatter regions are a mixture of shell hash, mud and sand; the latter exhibit populations of both abraded and unabraded grains. The shell hash is likely an erosional lag, perhaps remnants of the transgressive ravinement surface. The muds and unabraded grains are, because of negligible modern sediment input, evidence of newly eroded, previously undisturbed sediment. The lower-backscatter areas of the ribbon morphology consist of a well-sorted medium sand unit only a few tens of cm thick, overlying the shelly-muddy-sands. Well-rounded gravels and cobbles have been found in areas with very high backscatter; seismic data through one gravel mound indicates that it is likely derived from the base of an eroded fluvial/estuarine channel. Reworking of seafloor sediment in the post-transgressive regime appears to change from sand ridge evolution in inner to middle shelf depths to more predominantly erosional modification at outer shelf depths. We speculate that this change may be related to the reduction in the effectiveness of wave resuspension of sediment with increasing water depth.

Goff, J. A.; Austin, J. A.; Gulick, S.; Nordfjord, S.; Christensen, B.; Sommerfield, C.; Olson, H.; Alexander, C.

2004-12-01

409

Collisional inner-shell processes in highly-ionized Iron  

NASA Astrophysics Data System (ADS)

The RmaX consortium has been formed to study inner-shell processes of common astrophysical elements, including Fe. The aim is to calculate electron and photon collisional properties with atoms and ions for transitions in the soft X-Ray region. These calculations will exploit advances in the R-matrix outer-region codes (F. Robicheaux, T.W. Gorczyca, M.S. Pindzola and N.R. Badnell, Phys. Rev. A) 52 1319 (1995) to produce high precision data. Primarily, the Rydberg structure inherent in both excitation and photoionisation cross sections now allows for radiation damping. Radiation damping effects are evident in the higher members of any Rydberg series but can be more acutely felt in heavy, highly-charged systems. The results of initial calculations for Li-like and Be-like Fe will be presented. K- and L-shell electron- and photon-impact excitation and ionization as well as radiative rates for fine-structure levels are intended to be integrated into fundamental databases, such as ADAS. (H.P. Summers ADAS User manual Version 2.1) (1999).

Ballance, Connor P.; Badnell, Nigel R.; Berrington, Keith A.

2000-06-01

410

Binding energies for the inner hydration shells of Ca2+  

NASA Astrophysics Data System (ADS)

The sequential bond energies of Ca2+(H2O)x complexes, where x = 5-9, are determined by collision-induced dissociation (CID) using a guided ion beam tandem mass spectrometer with a recently developed electrospray ionization source. To our knowledge, this represents the first quantitative threshold CID study of multiply charged ions. The kinetic energy dependent cross sections are determined over a wide energy range to monitor all possible dissociation products and are modeled to obtain 0 and 298 K binding energies for loss of a single water molecule. These binding energies decrease monotonically for the Ca2+(H2O)5 complex to Ca2+(H2O)7 and plateau for Ca2+(H2O)7, Ca2+(H2O)8, and Ca2+(H2O)9. This suggests that six water molecules bind directly to the calcium ion and that three outer shell water molecules bind to inner shell water molecules through similar binding motifsE Our experimental results agree well with previous literature results obtained by equilibrium and BIRD studies. We also present an in-depth theoretical study of the structures and energetics of the Ca2+(H2O)x systems, employing several levels of theory. The present theoretical results focus on the larger hydrates (x = 8 and 9) where multiple low lying conformations are possible and there is little previous theory.

Carl, Damon R.; Moision, Robert M.; Armentrout, P. B.

2007-09-01

411

Convective Instabilities in Europa's Floating Ice Shell  

NASA Astrophysics Data System (ADS)

Models of the tidally heated ice shell proposed by Ojakangas and Stevenson for Europa generally find shell thicknesses less than 30 km. Past parameterized convection models indicate that these shell thicknesses are stable to convective overturn and should not lead to freezing of the ocean underneath. Here I apply the temperature- dependent viscosity convection scaling developed by Solomatov to the Europan ice shell. This scaling applies to basally heated square boxes with free-slip boundaries, which should be a good match to the Europan situation. The temperature-dependent properties of ice are linearized about 250 K, as any convective interior should be close to this temperature, with the colder ice forming an ostensibly passive, stagnant lid. Ice shells greater than ~ 20 km (at the equator) are found to be unstable to convection at their base, for melting point viscosities of 10(13) Pa-s. The critical shell thickness for convective onset is greater at the poles; it also depends on viscosity near the melting point, and so by the latest rheological laws, on grain size. Convection at the base of the ice shell does not freeze the ocean, however. Because of tidal heating, a "stagnant lid regime" ice shell is much more dissipative than a conductive shell of the same thickness. This causes a shell in which convection occurs to be thinner than a conductive shell undergoing the same tidal strain. The overall effect is to moderate the second-degree shell thickness variations found by Ojakangas and Stevenson (unless the shell is sufficiently thin to begin with), and impose an effective upper limit on the shell thickness. Tidal heating in the convecting base of the shell is non-uniform, which may lead to thermal instabilities, and the maximum stresses in the viscously creeping lid may be several 0.1 MPa, which could resolve as drag on the cold, elastic lithosphere. This research supported by NASA Planetary Geology and Geophysics grant NAG5- 3657.

McKinnon, W. B.

1997-07-01

412

Water hardness control by detergent builders  

Microsoft Academic Search

Commercial detergent additives to control water hardness are of three main types, sequestrant, precipitant or ion-exchange\\u000a builders. These builders lower the free hardness ion (Ca+2, Mg+2) concentration in a wash system by different mechanisms. An electrometric experimental method was used to evaluate the relative\\u000a water hardness control performances of different builder-types under conditions closely simulating those of detergent’s end-use.\\u000a Experimental

M. K. Nagarajan; H. L. Paine

1984-01-01

413

Shell Model Depiction of Isospin Mixing in sd Shell  

SciTech Connect

We constructed a new empirical isospin-symmetry breaking (ISB) Hamiltonian in the sd(1s{sub 1/2}, 0d{sub 5/2} and 0d{sub 3/2}) shell-model space. In this contribution, we present its application to two important case studies: (i){beta}-delayed proton emission from {sup 22}Al and (ii) isospin-mixing correction to superallowed 0{sup +}{yields}0{sup +}{beta}-decay ft-values.

Lam, Yi Hua; Smirnova, Nadya A. [CENBG (CNRS/IN2P3 - Universite Bordeaux 1) Chemin du Solarium, 33175 Gradignan (France); Caurier, Etienne [IPHC, IN2P3-CNRS et Universite Louis Pasteur, 67037 Strasbourg (France)

2011-11-30

414

Bimetallic Janus nanostructures via programmed shell growth.  

PubMed

We report the synthesis of compositionally asymmetric, core-Janus shell plasmonic nanostructures comprised of Au and Ag. Kinetic control was employed to achieve asymmetric shell growth on Au nanoparticles acting as cores. Subsequent differential surface functionalization of these nanostructures enabled programmed shell growth resulting in core-Janus shell nanostructures. UV/vis extinction spectra reveal that the localized surface plasmon resonance of the nanostructures depends on the composition and distribution of the components, providing additional handles to tune the optical properties of metal nanostructures. The core-Janus shell nanostructures demonstrated here are highly Raman-active making them attractive candidates for Raman-based biosensing and bioimaging applications. PMID:23386141

Gandra, Naveen; Portz, Christopher; Singamaneni, Srikanth

2013-02-06

415

Investigation of Li\\/Ca variations in aragonitic shells of the ocean quahog Arctica islandica, northeast Iceland  

Microsoft Academic Search

Interannual and intra-annual variations in lithium-to-calcium ratio were investigated with high temporal resolution in the aragonitic outer shell layer of juvenile Arctica islandica (Mollusca; Bivalvia) collected alive in 2006 off northeast Iceland. Li\\/Cashell ranged between 7.00 and 11.12 ?mol mol?1 and presented well-marked seasonal cycles with minimum values recorded at the annual growth lines; a general pattern was a progressive

Julien Thébault; Bernd R. Schöne; Nadine Hallmann; Matthias Barth; Elizabeth V. Nunn

2009-01-01

416

Magnetic Fields of the Outer Planets  

NASA Astrophysics Data System (ADS)

The rapidly rotating giant planets of the outer solar system all possess strong dynamo-driven magnetic fields that carve a large cavity in the flowing magnetized solar wind. Each planet brings a unique facet to the study of planetary magnetism. Jupiter possesses the largest planetary magnetic moment, 1.55×1020 Tm3, 2×104 times larger than the terrestrial magnetic moment whose axis of symmetry is offset about 10° from the rotation axis, a tilt angle very similar to that of the Earth. Saturn has a dipole magnetic moment of 4.6×1018 Tm3 or 600 times that of the Earth, but unlike the Earth and Jupiter, the tilt of this magnetic moment is less than 1° to the rotation axis. The other two gas giants, Uranus and Neptune, have unusual magnetic fields as well, not only because of their tilts but also because of the harmonic content of their internal fields. Uranus has two anomalous tilts, of its rotation axis and of its dipole axis. Unlike the other planets, the rotation axis of Uranus is tilted 97.5° to the normal to its orbital plane. Its magnetic dipole moment of 3.9×1017 Tm3 is about 50 times the terrestrial moment with a tilt angle of close to 60° to the rotation axis of the planet. In contrast, Neptune with a more normal obliquity has a magnetic moment of 2.2×1017 Tm3 or slightly over 25 times the terrestrial moment. The tilt angle of this moment is 47°, smaller than that of Uranus but much larger than those of the Earth, Jupiter and Saturn. These two planets have such high harmonic content in their fields that the single flyby of Voyager was unable to resolve the higher degree coefficients accurately. The four gas giants have no apparent surface features that reflect the motion of the deep interior, so the magnetic field has been used to attempt to provide this information. This approach works very well at Jupiter where there is a significant tilt of the dipole and a long baseline of magnetic field measurements (Pioneer 10 to Galileo). The rotation rate is 870.536° per day corresponding to a (System III) period of 9 h 55 min 26.704 s. At Saturn, it has been much more difficult to determine the equivalent rotation period. The most probable rotation period of the interior is close to 10 h 33 min, but at this writing, the number is still uncertain. For Uranus and Neptune, the magnetic field is better suited for the determination of the planetary rotation period but the baseline is too short. While it is possible that the smaller planetary bodies of the outer solar system, too, have magnetic fields or once had, but the current missions to Vesta, Ceres and Pluto do not include magnetic measurements.

Russell, C. T.; Dougherty, M. K.

2010-05-01

417

A Particle Simulation for the Pulsar Magnetosphere: Relationship of Polar Cap, Slot Gap, and Outer Gap  

NASA Astrophysics Data System (ADS)

To explain the pulsed emission of the rotation powered pulsars from radio to gamma-ray, polar cap models, slot gap models, and outer gap models are proposed. Recent observations suggest that these models are likely to co-exist in the same magnetosphere. If so, their mutual relation is known to be troublesome (Harding 2009), due to the boundary conditions and the direction of the current, which are properly assumed in each acceleration model. We performed a particle simulation for the global magnetospheric structure. Based on this simulation, we present a new picture of the global structure of the pulsar magnetosphere. It is found that a new dead zone is formed along the current neutral line that separates the oppositely directed current. We shall call this the current-neutral zone. We suggest that the polar cap accelerators and the slot gaps locate above the current-neutral zone, and the outer gap exist between the current neutral zone and the traditional dead zone. We also give an estimate of the super-rotation region.

Yuki, Shinya; Shibata, Shinpei

2012-06-01

418

Indentation of Ellipsoidal and Cylindrical Elastic Shells  

NASA Astrophysics Data System (ADS)

Thin shells are found in nature at scales ranging from viruses to hens’ eggs; the stiffness of such shells is essential for their function. We present the results of numerical simulations and theoretical analyses for the indentation of ellipsoidal and cylindrical elastic shells, considering both pressurized and unpressurized shells. We provide a theoretical foundation for the experimental findings of Lazarus et al. [following paper, Phys. Rev. Lett. 109, 144301 (2012)PRLTAO0031-9007] and for previous work inferring the turgor pressure of bacteria from measurements of their indentation stiffness; we also identify a new regime at large indentation. We show that the indentation stiffness of convex shells is dominated by either the mean or Gaussian curvature of the shell depending on the pressurization and indentation depth. Our results reveal how geometry rules the rigidity of shells.

Vella, Dominic; Ajdari, Amin; Vaziri, Ashkan; Boudaoud, Arezki

2012-10-01

419

Cell envelope and shape of Escherichia coli: multiple mutants missing the outer membrane lipoprotein and other major outer membrane proteins.  

PubMed Central

Starting with an Escherichia coli strain missing the outer membrane lipoprotein, multiple mutants were constructed than in addition to this defect miss the outer membrane proteins II, Ia and Ib, or Ia, Ib, and II. In contrast to all single mutants or strains missing the lipoprotein and polypeptides Ia and Ib, drastic influences on the integrity of the outer membrane and cell morphology were observed in mutants without lipoprotein and protein II. Such strains exhibited spherical morphology. They required increased concentrations of electrolytes for optimal growth, and Mg2+ or Ca2+ were the most efficient. These mutants were sensitive to hydrophobic antibiotics and detergents. Electron microscopy revealed abundant blebbing of the outer membrane, and it could clearly be seen that the murein layer was no longer associated with the outer membrane. Images

Sonntag, I; Schwarz, H; Hirota, Y; Henning, U

1978-01-01

420

Outer Continental Shelf Hard Minerals Leasing: Economic Feasibility Study of OCS Mining of Phosphorites Offshore Southern California.  

National Technical Information Service (NTIS)

The study sees offshore Southern California phosphorites as competing with Florida and Rocky Mountain phosphate rock for the Pacific Coast Markets. The study used the Port of Stockton, California as the central marketing point, and analyzed mineral recove...

1979-01-01

421

Moderately large vibrations of doubly curved shallow open shells composed of thick layers  

NASA Astrophysics Data System (ADS)

This paper addresses nonlinear flexural vibrations of shallow shells composed of three thick layers with different shear flexibility, which are symmetrically arranged with respect to the middle surface. The considered shell structures of polygonal planform are hard hinged simply supported (i.e. all in-plane rotations and the bending moment vanish) with the edges fully restraint against displacements in any direction. The kinematic field equations are formulated by layerwise application of a first-order shear deformation theory. A modification of Berger's theory is employed to model the nonlinear characteristics of the structural response. The continuity of the transverse shear stress across the interfaces is specified according to Hooke's law, and subsequently the equations of motion of this higher order problem can be derived in analogy to a homogeneous single-layer shear deformable shallow shell. Numerical results of rectangular shallow shells in nonlinear steady-state vibration are presented for various ratios of shell rise to thickness, and non-dimensional load amplitude.

Adam, Christoph

2007-02-01

422

Celestial mechanics of planet shells  

Microsoft Academic Search

The motion of a planet consisting of an external shell (mantle) and a core (rigid body), which are connected by a visco-elastic layer and mutually gravitationally interact with each other and with an external celestial body (considered as a material point), is studied (Barkin, 1999, 2002a,b; Vilke, 2004). Relative motions of the core and mantle are studied on the assumption

Yu V. Barkin; V. G. Vilke

2004-01-01

423

Case Study: AWARE at Shell  

Microsoft Academic Search

\\u000a In Chap. 10, Monique de Wit, Henry van Straten, and Mandar Apte describe AWARE (at work a global initiative of employees in\\u000a Shell with the objective of reducing stress and increasing self-awareness and interpersonal effectiveness). AWARE is a bottom\\u000a up, “staff helping staff” initiative that organizes learning workshops and sessions based on yoga, meditation, and profound breathing techniques for\\u000a all

Monique Wit; Henry Straten; Mandar Apte

424

Slow pyrolysis of pistachio shell  

Microsoft Academic Search

In this study, pistachio shell is taken as the biomass sample to investigate the effects of pyrolysis temperature on the product yields and composition when slow pyrolysis is applied in a fixed-bed reactor at atmospheric pressure to the temperatures of 300, 400, 500, 550, 700°C. The maximum liquid yield was attained at about 500–550°C with a yield of 20.5%. The

Esin Apaydin-Varol; Ersan Pütün; Ay?e E. Pütün

2007-01-01

425

Properties and Implications of Radial Transport in the Outer Electron Belt  

NASA Astrophysics Data System (ADS)

Earth's outer radiation belt extends above approximately 3.5 Re and is populated by relativistic electrons trapped in the geomagnetic field. Radiation levels across the belt can vary by multiple orders of magnitude on the time scales ranging from minutes to days. One of the basic processes leading to global variability of radiation levels in the belt is radial transport of electrons across their drift shell. The inward radial diffusion followed by "adiabatic" acceleration was the first mechanism put forward to explain creation of the outer belt. This paper reviews the results of recent analysis of basic properties of radial transport and discusses their implications to the global state of the belt. We will focus on stochastic transport which traditionally is referred to as radial diffusion. Stochastic radial transport is driven by interactions of the gradient curvature motion of the electron guiding center with ULF waves. Long-term electron motion can become stochastic due to non-linearity of electron interaction with the waves as well as to the random nature of their solar-wind driver. In spite of the underlying stochasticity the radial diffusion limit is not fully attainable in the outer radiation belt. This is attributed to the fact that phase correlations in electron motion do not have time to decay due to finite size of the system. As a result collective motion of the outer belt electrons can exhibit large deviations from radial diffusion. We will also discuss how the electron belt is affected by drift orbit bifurcations (DOBs). In a day-side compressed geomagnetic field electron orbits around Earth can exhibit bifurcations which violate their second adiabatic invariant and produce complex non-diffusive radial transport. Consequently, the third invariant is undefined for the bifurcating orbits, which means that electron motion can no not be analyzed in terms of adiabatic invariants. Even during quiet solar wind conditions DOBs affect a broad region of the belt penetrating inside the geosynchronous orbit. The pitch-angle and radial transport due to DOBs leads to their meandering back and forth across the region, producing mixing and recirculation of particle populations with different initial conditions at the time rates comparable or higher to standard radial transport estimates. Electron recirculation can greatly amplify the efficiency of acceleration by radial transport: the combined action of radial transport and DOBs can produce a factor of two increase in electron energization at each recirculation cycle.

Ukhorskiy, A. Y.; Sitnov, M. I.; Millan, R. M.; Kress, B. T.

2011-12-01

426

Influence of Substrate Hardness on the Properties of PVD Hard Coatings  

Microsoft Academic Search

Nowadays, hard coatings based on transition metal nitrides are extensively used for materials protection and particularly to improve the lifetime and performance of various cutting and forming tools. Practically, hard coatings need to be deposited on different kinds of substrate materials in different application areas. The physical properties, such as hardness, of the substrate may have evident influence on the

X. T. Zeng; Y. C. Liu; J. Wei; P. Holiday

2008-01-01

427

Phospholipid composition of highly purified mitochondrial outer membranes of rat liver and Neurospora crassa. Is cardiolipin present in the mitochondrial outer membrane?  

Microsoft Academic Search

Isolated mitochondrial outer membrane vesicles (OMV) are a suitable system for studying various functions of the mitochondrial outer membrane. For studies on mitochondrial lipid import as well as for studies on the role of lipids in processes occurring in the outer membrane, knowledge of the phospholipid composition of the outer membrane is indispensable. Recently, a mild subfractionation procedure was described

Anton I. P. M de Kroon; Danièle Dolis; Andreas Mayer; Roland Lill; Ben de Kruijff

1997-01-01

428

Regulating Mitochondrial Outer Membrane Proteins by Ubiquitination and Proteasomal Degradation  

PubMed Central

Mitochondrial outer membrane proteins have been found to be ubiquitinated and degraded by the proteasome. This process shares at least one component of the ERAD pathway of ER membrane protein degradation, the AAA ATPase cdc48/p97/VCP, thought to extract integral membrane proteins from the lipid bilayer and chaperone them to the proteasome. Proteasomal degradation of the outer mitochondrial membrane protein Mcl-1 regulates apoptosis whereas Parkin-mediated ubiquitination and degradation of Mitofusins can inhibit mitochondrial fusion and promote mitophagy. The breadth of outer mitochondrial membrane ubiquitin/proteasome substrates and the physiological relevance of their turnover is only beginning to be understood.

Karbowski, Mariusz; Youle, Richard J.

2011-01-01

429

Development of the Outer Surface Irradiated Laser Stress Improvement Process  

NASA Astrophysics Data System (ADS)

Outer Surface Irradiated Laser Stress Improvement Process (L-SIP) was developed as a counter measure for stress corrosion cracking at the tube and nozzle stub weld in the nuclear power plant and the thermal power plant. L-SIP is a technique for improving the inside tensile residual stress to the compressive stress. Rapidly heating by the laser beam irradiation to outer surface causes the temperature difference between outer surface and inner surface, and it can reduce the residual stress. In this paper, the developed system, the verification test results and the practical use situation are described.

Tsubota, Shuho; Kamo, Kazuhiko; Ohta, Takahiro; Ishide, Takashi; Nakamura, Yasuo; Ueda, Takeshi; Onitsuka, Hironori; Akaba, Takashi

430

Polar Phenomena in Outer Planet Atmospheres  

NASA Astrophysics Data System (ADS)

Infrared observations of the polar regions of the outer planets have revealed similarities to the Earth's atmosphere and some new phenomena. The most dominant force which is apparent in time-dependent studies of the poles is seasonal radiative forcing, which was detected in Saturn's stratosphere as early as 1973. For Saturn, Uranus and Neptune, planets with substantial obliquities, the seasonally dependent changes are predictable and can be used to constrain abundances of optically active gases and the rate of restoration by stratospheric circulation. In the case of Neptune, recent evidence shows that the heating is sufficient to allow a "leak" from the reservoir of methane in the deep atmosphere into the polar stratosphere. New thermal images of Uranus show that the winter pole of Uranus which has only recently emerged fully from darkness is colder than when it was in the middle of winter when Voyager 2 visited, confirming the substantial seasonal phase delay associated with radiative heating and cooling models. Even Jupiter with its 3-degree obliquity shows clear evidence for seasonal forcing of temperatures in the upper troposphere and stratosphere. The second most prominent characteristic of the resolvable polar temperature fields in Jupiter and Saturn is the formation of polar vortices. Jupiter's polar vortices are cold, similar to those detected in the terrestrial planets; they have sharp equatorward boundaries which are characterized by Rossby waves which rotate at the speed of the local zonal wind flow and are coincident with the similarly irregular boundaries of a polar haze, also known as "polar hoods". The cold vortex at Saturn's northern winter pole is muted, but Saturn also has a unique "warm polar vortex" in the south (late summer) pole which shows no apparent wave structure. Saturn's warm polar vortex has no counterpart in the Earth's atmosphere, where summer radiative warming simply dissipates the cold winter vortex. Saturn also possesses dynamically driven hot regions within 2 degrees of its poles where dynamics is driving relatively dry air downwards, causing adiabatic warming and clearing the atmosphere; this phenomenon also has no terrestrial counterpart. Jupiter's upper polar stratosphere is warmed in discrete local regions by Joule heating from energetic particles cascading into the neutral atmosphere. The northern auroral-related polar "hot spot" has a very predictable geometry, but an amplitude that is variable over time scales of months. On the other hand, the stratosphere 25-30 degrees from Neptune's pole shows signs of ephemeral hot spots which are more likely to related to dynamics. These phenomena provide a rich basis of constraints for global climate models which must, at least for Jupiter, be coupled with models of auroral energy transport.

Orton, G.; Fletcher, L.; Yanamandra-Fisher, P.; Leyrat, C.; Greathouse, T.; Parrish, P.; Encrenaz, T.; Simon-Miller, A.

2008-12-01

431

Synthesis of hierarchical hollow silica microspheres containing surface nanoparticles employing the quasi-hard template of poly(4-vinylpyridine) microspheres.  

PubMed

A facile method of preparing hierarchical hollow silica microspheres containing surface silica nanoparticles (HHSMs) through the sol-gel process of tetraethylorthosilicate employing a quasi-hard template of non-cross-linking poly(4-vinylpyridine) microspheres is proposed. The quasi-hard template contains the inherent catalyst of the basic pyridine group, and a few of the polymer chains can escape from the template matrix into the aqueous phase, which initiates the sol-gel process spontaneously both on the surface of the template used to prepare the hollow silica shell and in the aqueous phase to produce the surface silica nanoparticles. By tuning the weight ratio of the silica precursor to the quasi-hard template, HHSMs with a size of about 180 nm and a shell thickness ranging from 14 to 32 nm and surface silica nanoparticles ranging from 17 to 36 nm are produced initially through the deposition of surface silica nanoparticles onto the silica shell, followed by template removal either by calcination or solvent extraction. The synthesized HHSMs are characterized, and a possible mechanism for the synthesis of HHSMs is proposed. PMID:21671559

Su, Yang; Yan, Rui; Dan, Meihan; Xu, Jianxiong; Wang, Da; Zhang, Wangqing; Liu, Shuangxi

2011-06-23

432

After Hard Drives—What Comes Next?  

Microsoft Academic Search

There are numerous emerging nonvolatile memory technologies, which have been proposed as being capable of replacing hard disk drives (HDDs). In this paper, the prospects for these alternative technologies to displace HDDs in 2020 are analyzed. In order to compare technologies, projections were made of storage density and performance in year 2020 for both hard disks and the alternative technologies,

Mark H. Kryder; Chang Soo Kim

2009-01-01

433

"Hard Science" for Gifted 1st Graders  

ERIC Educational Resources Information Center

|"Hard Science" is designed to teach 1st grade gifted students accurate and high level science concepts. It is based upon their experience of the world and attempts to build a foundation for continued love and enjoyment of science. "Hard Science" provides field experiences and opportunities for hands-on discovery working beside experts in the…

DeGennaro, April

2006-01-01

434

HARD SPRING WHEAT TECHNICAL COMMITTEE 2007 CROP  

Technology Transfer Automated Retrieval System (TEKTRAN)

Twelve experimental lines of hard spring wheat were grown at up to five locations in 2007 and evaluated for kernel, milling, and bread baking quality against the check variety Glenn. Samples of wheat were submitted through the Wheat Quality Council and processed and milled at the USDA Hard Red Spri...

435

Etch durable spin-on hard mask  

Microsoft Academic Search

As decreasing the device feature size, the film stack structure used in resist process is also changing. Especially multilayer stack film structure is getting popular for pattern formation on critical layers. Our approach is to form a spin-on hard mask film with high etch resistance by introduction of a new baking function. The results show that a spin-on hard mask

Makoto Muramatsu; Mitsuaki Iwashita; Takashi Kondo; Hisashi Hirose; Seiji Fujimoto

2011-01-01

436

Roller burnishing of hard turned surfaces  

Microsoft Academic Search

In a hard roller burnishing operation, a hydrostatically borne ceramic ball rolls over the component surface under high pressures. The roughness peaks are flattened and the quality of the workpiece surface is improved. When combined with hard turning, this process provides a manufacturing alternative to grinding and honing operations.The studies determined optimum working parameter ranges. Parameter settings were shown to

F. Klocke; J. Liermann

1998-01-01

437

Rockwell Hardness Measurement of Metallic Materials.  

National Technical Information Service (NTIS)

The Rockwell hardness test continues to be applied as a tool for assessing the properties of a product while the tolerances on the acceptable material hardness have become tighter and tighter. The once-thought-of manufacturing tool has developed into a me...

S. R. Low

2001-01-01

438

Relation of Microindentation Hardness to Glass Composition.  

National Technical Information Service (NTIS)

Microindentation hardness measurements on Na2O-CaO-SiO2 and Na2O-Al2O3SiO2 glasses showed that Knoop hardness numbers are linearly related to oxide compositions expressed in mole fraction. Evaluations of the data indicate that these linear relations are u...

A. N. Georoff C. L. Babcock

1972-01-01

439

Radiation hardness studies of CVD diamond detectors  

Microsoft Academic Search

The inherent properties of diamond make it an ideal material for tracking detectors especially in the high rate, high radiation environments of future colliders such as the LHC. In order to survive in this environment, detectors must be radiation hard. We have constructed charged particle detectors using high quality CVD diamond and performed radiation hardness tests on them. The signal

C. Bauer; I. Baumann; C. Colledani; J. Conway; P. Delpierre; F. Djama; W. Dulinski; A. Fallou; K. K. Gan; R. S. Gilmore; E. Grigoriev; G. Hallewell; S. Han; T. Hessing; K. Honschied; J. Hrubec; D. Husson; H. Kagan; D. Kania; R. Kass; W. Kinnison; K. T. Knöpfle; M. Krammer; T. J. Llewellyn; P. F. Manfredi; L. S. Pan; H. Pernegger; M. Pernicka; R. Plano; V. Re; S. Roe; A. Rudge; M. Schaeffer; S. Schnetzer; S. Somalwar; V. Speziali; R. Stone; R. J. Tapper; R. Tesarek; W. Trischuk; R. Turchetta; G. B. Thomson; R. Wagner; P. Weilhammer; C. White; H. Ziock; M. Zoeller

1995-01-01

440

Rad Hard Active Media For Calorimeters  

Microsoft Academic Search

Zero-degree calorimeters have limited space and extreme levels of radiation. A simple, low cost, radiation hard design uses tungsten metal as the absorber and a suitable liquid as the Cerenkov radiator. In other applications a PPAC (Parallel Plate Avalanche Counter) operating with a suitable atmospheric-pressure gas is an attractive active material for a calorimeter. It can be made radiation hard

E. Norbeck; J. E. Olson; A. Moeller; Y. Onel

2006-01-01

441

Hard Metal Alveolitis Accompanied by Rheumatoid Arthritis  

Microsoft Academic Search

Hard metal lung diseases (HML) are rare, and complex to diagnose. We describe the case of a patient with allergic alveolitis accompanied by rheumatoid arthritis. A sharpener of hard metal by trade, our patient was a 45-year-old, nonsmoking Caucasian female who experienced symptoms of cough and phlegm, and dyspnea on exertion. Preliminary lung findings were inspiratory rales in both basal

Paula A. Hahtola; Ritva E. Järvenpää; Kari Lounatmaa; Jorma J. Mattila; Immo Rantala; Jukka A. Uitti; Seppo Sutinen

2000-01-01

442

Bimetallic Janus nanostructures via programmed shell growth  

NASA Astrophysics Data System (ADS)

We report the synthesis of compositionally asymmetric, core-Janus shell plasmonic nanostructures comprised of Au and Ag. Kinetic control was employed to achieve asymmetric shell growth on Au nanoparticles acting as cores. Subsequent differential surface functionalization of these nanostructures enabled programmed shell growth resulting in core-Janus shell nanostructures. UV/vis extinction spectra reveal that the localized surface plasmon resonance of the nanostructures depends on the composition and distribution of the components, providing additional handles to tune the optical properties of metal nanostructures. The core-Janus shell nanostructures demonstrated here are highly Raman-active making them attractive candidates for Raman-based biosensing and bioimaging applications.We report the synthesis of compositionally asymmetric, core-Janus shell plasmonic nanostructures comprised of Au and Ag. Kinetic control was employed to achieve asymmetric shell growth on Au nanoparticles acting as cores. Subsequent differential surface functionalization of these nanostructures enabled programmed shell growth resulting in core-Janus shell nanostructures. UV/vis extinction spectra reveal that the localized surface plasmon resonance of the nanostructures depends on the composition and distribution of the components, providing additional handles to tune the optical properties of metal nanostructures. The core-Janus shell nanostructures demonstrated here are highly Raman-active making them attractive candidates for Raman-based biosensing and bioimaging applications. Electronic supplementary information (ESI) available: Materials and methods. See DOI: 10.1039/c3nr34321a

Gandra, Naveen; Portz, Christopher; Singamaneni, Srikanth

2013-02-01

443

Hardness methods for testing maize kernels.  

PubMed

Maize is a highly important crop to many countries around the world, through the sale of the maize crop to domestic processors and subsequent production of maize products and also provides a staple food to subsistance farms in undeveloped countries. In many countries, there have been long-term research efforts to develop a suitable hardness method that could assist the maize industry in improving efficiency in processing as well as possibly providing a quality specification for maize growers, which could attract a premium. This paper focuses specifically on hardness and reviews a number of methodologies as well as important biochemical aspects of maize that contribute to maize hardness used internationally. Numerous foods are produced from maize, and hardness has been described as having an impact on food quality. However, the basis of hardness and measurement of hardness are very general and would apply to any use of maize from any country. From the published literature, it would appear that one of the simpler methods used to measure hardness is a grinding step followed by a sieving step, using multiple sieve sizes. This would allow the range in hardness within a sample as well as average particle size and/or coarse/fine ratio to be calculated. Any of these parameters could easily be used as reference values for the development of near-infrared (NIR) spectroscopy calibrations. The development of precise NIR calibrations will provide an excellent tool for breeders, handlers, and processors to deliver specific cultivars in the case of growers and bulk loads in the case of handlers, thereby ensuring the most efficient use of maize by domestic and international processors. This paper also considers previous research describing the biochemical aspects of maize that have been related to maize hardness. Both starch and protein affect hardness, with most research focusing on the storage proteins (zeins). Both the content and composition of the zein fractions affect hardness. Genotypes and growing environment influence the final protein and starch content and, to a lesser extent, composition. However, hardness is a highly heritable trait and, hence, when a desirable level of hardness is finally agreed upon, the breeders will quickly be able to produce material with the hardness levels required by the industry. PMID:19496585

Fox, Glen; Manley, Marena

2009-07-01

444

Hardness of group IVA and IVB nitrides  

NASA Astrophysics Data System (ADS)

The hardnesses of various phases of group IVA and IVB nitrides (M3N4, M=C, Si, Ge, Sn, Ti, Zr or Hf; MN, M=Ti, Zr or Hf) were calculated using the bond electronegativity model for material hardness. The hardnesses of group IV nitrides increase with an increase in their average coordination numbers except for carbon nitrides, for which increasing the average coordination numbers results in a reduction in hardness. We suggest that for light-element compounds, the diamond-like structure represents the hardest one among all possible structures, whereas a high coordination number is generally required for heavy-element compounds to achieve high hardness values. This work provides a useful guide for designing novel nitride materials having excellent mechanical performances.

Li, Keyan; Xue, Dongfeng

2010-05-01

445

Synthesis and characterization of model silica-gold core-shell nanohybrid systems to demonstrate plasmonic enhancement of fluorescence  

NASA Astrophysics Data System (ADS)

In this work, gold-silica plasmonic nanohybrids have been synthesized as model systems which enable tuning of dye fluorescence enhancement/quenching interactions. For each system, a dye-doped silica core is surrounded by a 15 nm spacer region, which in turn is surrounded by gold nanoparticles (GNPs). The GNPs are either covalently conjugated via mercapto silanization to the spacer or encapsulated in a separate external silica shell. The intermediate spacer region can be either dye doped or left undoped to enable quenching and plasmonic enhancement effects respectively. The study indicates that there is a larger enhancement effect when GNPs are encapsulated in the outer shell compared to the system of external conjugation. This is due to the environmental shielding provided by shell encapsulation compared to the exposure of the GNPs to the solvent environment for the externally conjugated system. The fluorescence signal enhancement of the nanohybrid systems was evaluated using a standard HRP-anti-HRP fluorescence based assay platform.

Roy, Shibsekhar; Dixit, Chandra K.; Woolley, Robert; O'Kennedy, Richard; McDonagh, Colette

2012-08-01

446

Shell evolution in the sd-pf shell studied by the shell model  

SciTech Connect

The structure of unstable nuclei around N = 28 is studied by large-scale shell-model calculations with a new effective interaction including a proper tensor force. The dominance of the tensor force is seen in several observables. The effect appears not only in the single-hole states in K isotopes but also in the occurance of large deformation in {sup 42}Si and in the distribution of the spectroscopic factors for proton pickup from {sup 48}Ca.

Utsuno, Yutaka [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Otsuka, Takaharu [Department of Physics and Center for Nuclear Study, University of Tokyo, Hongo Tokyo 113-0033 (Japan); RIKEN Nishina Center, Hirosawa, Wako Saitama 351-0198 (Japan); National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing MI 48824 (United States); Brown, B. Alex [Department of Physics and Astronomy, Michigan State University, East Lansing MI 48824 (United States); National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing MI 48824 (United States); Honma, Michio [Center for Nuclear Study, Aizu University, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580 (Japan); Mizusaki, Takahiro [Institute for National Sciences, Senshu University, Tama, Kawasaki, Kanagawa 214-8580 (Japan)

2009-05-04

447

Ion microprobe assessment of the heterogeneity of Mg/Ca, Sr/Ca and Mn/Ca ratios in Pecten maximus and Mytilus edulis (bivalvia) shell calcite precipitated at constant temperature  

NASA Astrophysics Data System (ADS)

Small-scale heterogeneity of biogenic carbonate elemental composition can be a significant source of error in the accurate use of element/Ca ratios as geochemical proxies. In this study ion microprobe (SIMS) profiles showed significant small-scale variability of Mg/Ca, Sr/Ca and Mn/Ca ratios in new shell calcite of the marine bivalves Pecten maximus and Mytilus edulis that was precipitated during a constant-temperature culturing experiment. Elevated Mg/Ca, Sr/Ca and Mn/Ca ratios were found to be associated with the deposition of elaborate shell features, i.e. a shell surface stria in P. maximus and surface shell disturbance marks in both species, the latter a common occurrence in bivalve shells. In both species the observed small-scale elemental heterogeneity most likely was not controlled by variable transport of ions to the extra-pallial fluid, but by factors such as the influence of shell organic content and/or crystal size and orientation, the latter reflecting conditions at the shell crystal-solution interface. In the mid and innermost regions of the P. maximus shell the lack of significant small-scale variation of Mg/Ca ratios, which is consistent with growth at constant temperature, suggest a potential application as a palaeotemperature proxy. Cross-growth band element/Ca ratio profiles in the interior of bivalve shells may provide more promising palaeo-environmental tools than sampling from the outer region of bivalve shells.

Freitas, P. S.; Clarke, L. J.; Kennedy, H.; Richardson, C. A.

2009-07-01

448

Single- and double-shelled coaxial nanocables of GaP with silicon oxide and carbon.  

PubMed

Coaxial nanocables of gallium phosphide (GaP) core with three different-typed single and double shells (i.e., silicon oxide (SiO(x)), carbon (C), and SiO(x)/C) were exclusively synthesized by the chemical vapor deposition method. The GaP/SiO(x)) nanocables were directly grown on gold-deposited silicon substrates. Deposition of C on the GaP nanowires and GaP/SiO(x) nanocables produces the GaP/C and GaP/SiO(x)/C nanocables, respectively. The outer diameter of the nanocables is <50 nm. The thickness and crystallinity of the C outer layers were controllable by the growth conditions. X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, and photoluminescence reveal that the outer layer formation reduces the surface defects of GaP nanowires. A great enhancement of the conductivity due to the C outer layers has been measured by the four-probe method. The growth process of these nanocables has been discussed on the basis of the vapor-liquid-solid mechanism. PMID:16851998

Bae, Seung Yong; Seo, Hee Won; Choi, Hyun Chul; Han, Doo Suk; Park, Jeunghee

2005-05-01

449

Low-Energy Nondipole Effects in Molecular Nitrogen Valence-Shell Photoionization  

SciTech Connect

Observations are reported for the first time of significant nondipole effects in the photoionization of the outer-valence orbitals of diatomic molecules. Measured nondipole angular-distribution parameters for the 3{sigma}{sub g}, 1{pi}{sub u}, and 2{sigma}{sub u} shells of N{sub 2} exhibit spectral variations with incident photon energies from thresholds to {approx}200 eV which are attributed via concomitant calculations to particular final-state symmetry waves arising from (E1)(multiply-in-circle sign)(M1,E2) radiation-matter interactions first-order in photon momentum. Comparisons with previously reported K-edge studies in N{sub 2} verify linear scaling with photon momentum, accounting in part for the significantly enhanced nondipole behavior observed in inner-shell ionization at correspondingly higher momentum values in this molecule.

Hemmers, O.; Lindle, D. W. [Department of Chemistry, University of Nevada, Las Vegas, Nevada 89154-4003 (United States); Guillemin, R.; Wolska, A. [Department of Chemistry, University of Nevada, Las Vegas, Nevada 89154-4003 (United States); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Rolles, D. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kanter, E. P.; Kraessig, B.; Southworth, S. H. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Wehlitz, R. [Synchrotron Radiation Center, University of Wisconsin, Stoughton, Wisconsin 53589 (United States); Zimmermann, B. [Max-Planck-Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, D-01189 Dresden (Germany); A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125 (United States); McKoy, V. [A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125 (United States); Langhoff, P. W. [San Diego Supercomputer Center, University of California, La Jolla, California 92093 (United States)

2006-09-08

450

Critical stability of almost adiabatic convection in a rapidly rotating thick spherical shell  

NASA Astrophysics Data System (ADS)

In this work, the convection equations in the almost adiabatic approximation is studied for which the choice of physical parameters is primarily based on possible applications to the hydrodynamics of the deep interiors of the Earth and planets and moons of the terrestrial group. The initial system of partial differential equations (PDEs) was simplified to a single second-order ordinary differential equation for the pressure or vertical velocity component to investigate the linear stability of convection. The critical frequencies, modified Rayleigh numbers, and distributions of convection are obtained at various possible Prandtl numbers and in different thick fluid shells. An analytical WKB-type solution was obtained for the case when the inner radius of the shell is much smaller than the outer radius and convective sources are concentrated along the inner boundary.

Starchenko, S. V.; Kotelnikova, M. S.

2013-02-01

451

Controlled synthesis of monodisperse SiO(2)--TiO(2) microspheres with a yolk-shell structure as effective photocatalysts.  

PubMed

Monodisperse yolk-shell SiO(2) -TiO(2) microspheres were synthesized using core-shell silica microspheres as templates. In the absence of prior surface modifications, a uniform coating of the TiO(2) layer on the core-shell silica was achieved through a sol-gel route. Mesoporous silica shells between the outer TiO(2) shell and the SiO(2) core were selectively removed by using a weak base, yielding yolk-shell SiO(2) -TiO(2) microspheres (ys-SiO(2) @TiO(2) ). Using the same templates, we synthesized Pt-encased microspheres (SiO(2) @Pt-TiO(2) ), in which Pt nanoparticles are embedded between the SiO(2) core and the TiO(2) shell. Selective etching of the silica shells in SiO(2) @Pt-TiO(2) yields Pt-encased yolk-shell SiO(2) -TiO(2) microspheres (ys-S