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1

Radiation hardness of the LHCb Outer Tracker  

NASA Astrophysics Data System (ADS)

This paper presents results on the radiation hardness of the LHCb Outer Tracker (OT) during LHC operation in 2010 and 2011. Modules of the OT have shown to suffer from ageing effects that lead to gain loss, after irradiation in the laboratory. Under irradiation at moderate intensities an insulating layer is formed on the anode wire of the OT straw cells. This ageing effect is caused by contamination of the counting gas due to outgassing of the glue used in the construction of the OT modules. Two methods to monitor gain stability in the OT are presented: module scans with radioactive sources and the study of hit efficiency as a function of amplifier threshold. No gain loss is observed after receiving 1.3 fb-1 of integrated luminosity corresponding to an integrated charge of 0.055 C/cm in the hottest spot of the detector.

van Eijk, D.; Bachmann, S.; Bauer, Th.; Färber, Ch.; Bien, A.; Coco, V.; Deckenhoff, M.; Dettori, F.; Ekelhof, R.; Gersabeck, E.; Karbach, T. M.; Koopman, R.; Kozlinskiy, A.; Langenbruch, Ch.; Linn, Ch.; Merk, M.; Meissner, M.; Morawski, P.; Pellegrino, A.; Serra, N.; Seyfert, P.; Spaan, B.; Swientek, S.; Storaci, B.; Szczekowski, M.; Tuning, N.; Uwer, U.; Visser, E.; Wiedner, D.; Witek, M.

2012-09-01

2

Metal oxide-hydrogen battery having an outer safety shell  

SciTech Connect

A metal oxide hydrogen battery assembly is described, comprising a metal oxide hydrogen battery having an outer pressure vessel and having at least one cell module contained within the pressure vessel, said pressure vessel containing pressurized hydrogen gas, said cell module having a positive and a negative terminal, an outer gas-impermeable shell disposed around the pressure vessel to provide a space there between, electrical connecting means connected to said terminals and extending through said pressure vessel and extending to the exterior of said shell, and vent conduit means communicating with said space for venting any hydrogen gas leaking from said pressure vessel from said space to the exterior.

Jones, K.R.

1993-06-01

3

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

4

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

NASA Technical Reports Server (NTRS)

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

Pokrovskiy, G. I.

1974-01-01

5

On the strong influence of inner shell resonances upon the outer shell photoionization of endohedral atoms  

NASA Astrophysics Data System (ADS)

It is demonstrated by the example of the Xe atom stuffed inside the C60 fullerene, i.e., the endohedral Xe@C60, that the so-called confinement resonances in 4 d subshell strongly affect the photoionization cross section of outer 5 p and subvalent 5 s electrons near the 4 d ionization threshold. It is a surprise that these narrow inner 4 d shell resonances are not smeared out in the outer shell photoionization cross section. On the contrary; the inner shell resonances affect the outer cross section by enhancing them enormously. Close to its own photoionization thresholds, 5 p and 5 s photoionization cross sections of Xe@C60 are dominated by their own confinement resonances greatly affected by the amplification of the incoming radiation intensity due to polarization by it of the C60 electron shell. Between 4 d and 5 p thresholds, the effect of 4 d is becoming stronger while own resonances of 5 p and 5 s are becoming much less important.

Amusia, M. Ya.; Chernysheva, L. V.

2012-03-01

6

Inner shell resonances in the outer shell photoionization of Xe@C60  

NASA Astrophysics Data System (ADS)

Fullerenes C60 can be stuffed by almost all atoms A or even simple molecules. It is demonstrated by the example of the 5p-subshell of the Xe atom stuffed inside the C60 fullerene, i.e. the endohedral Xe@C60 that the so-called confinement resonances in 4d subshell strongly affect the absolute and differential in the photoelectron emission angle cross-section of 5p electrons photoionization in the region of 4d ionization threshold. It is a sort of a surprise that the narrow inner shell resonances are not smeared out in the outer shell photoionization cross-section. Inner shell resonances affect the outer cross-section by enhancing this enormously and modifying 5p dipole and non-dipole angular anisotropy parameters. Close to its own photoionization threshold, 5p photoionization cross-section of Xe@C60 is dominated by its own confinement resonances greatly enhanced by the intensity of incoming radiation due to polarization of the C60 electron shell by the incoming photon beam. In between, the 4d and 5p thresholds, the effect of 4d is becoming stronger while own resonances of 5p are becoming less and less important.

Amusia, Miron; Chernysheva, Larissa

2012-06-01

7

77 FR 27054 - Notice of Approval of Clean Air Act Outer Continental Shelf Permits Issued to Shell Offshore, Inc...  

Federal Register 2010, 2011, 2012, 2013

...Air Act Outer Continental Shelf Permits Issued to Shell Offshore, Inc. for the Kulluk Conical Drilling...construct and Title V air quality operating permit to Shell Offshore, Inc. (``Shell'') for operation of the Kulluk conical...

2012-05-08

8

77 FR 7148 - Notice of Approval of Clean Air Act Outer Continental Shelf Permits Issued to Shell Gulf of...  

Federal Register 2010, 2011, 2012, 2013

...Air Act Outer Continental Shelf Permits Issued to Shell Gulf of Mexico, Inc., and Shell Offshore, Inc. for the Discoverer Drillship AGENCY...Continental Shelf (OCS) permit applications, one from Shell Gulf of Mexico, Inc., for operation of the...

2012-02-10

9

Matrix proteins in the outer shells of molluscs.  

PubMed

The shells of molluscs are composed mainly of calcium carbonate crystals, with small amounts of matrix proteins. For more than 50 years, they have attracted attention for their unique mechanical and biological properties. Only recently, however, have researchers begun to realize that it is the matrix proteins that control the formation of calcium carbonate crystals and play key roles in their extraordinary properties, despite the fact that matrix proteins comprise less than 5% of the shell weight. This article reviews the matrix proteins identified to date from the shells of molluscs, their structural characteristics, and their roles in shell formation. Some suggestions are given for further investigation based on the summary and analysis. PMID:16614870

Zhang, Cen; Zhang, Rongqing

2006-01-01

10

Strong exchange coupling in conventional and inverse ferrimagnetic hard/soft and soft/hard core/shell heterostructured nanoparticles  

NASA Astrophysics Data System (ADS)

Bi-magnetic core/shell nanoparticles are becoming increasingly appealing for diverse fields such as for permanent magnets, microawave absortion, biomedical applications, sensing applications, or future magnetic recording media. Ferrromagnetic (FM)/ antiferromagnetic (AFM) core/shell nanoparticles (or inverted AFM/FM) have been extensively studied. However, exchange coupled hard/soft, or inverse soft/hard, core/shell nanoparticles have been far less investigated. Interestingly, most bi-magnetic core/shell systems are derived by simple partial oxidation of the core, e.g., Co/CoO (FM/AFM) or FePt/Fe3O4 (hard/soft) and only few studies of heterostructured (where core and shell are formed by different magnetic ions) can be found in the literature. We have investigated conventional hard/soft and inverted soft/hard core/shell hetroestructured nanoparticles based on magnetically soft iron oxide (Fe3O4) and magnetically hard manganese oxide (Mn3O4). The core/shell samples were synthesized by seeded growth using either Fe3O4 or Mn3O4 nanoparticles as seeds. Subsequently, thin layers of the complementary material were grown by thermal decomposition of the corresponding metallorganic precursors. The structure characterization (X-ray diffraction and electron diffraction) confirms the presence of cubic (Fe3O4) and tetragonal (Mn3O4) phases both at the bulk and local levels. In addition, high resolution transmission electron microscopy (HR-TEM) with electron energy loss spectroscopy (EELS) mapping confirms the core/shell structure of the nanopartciles. Magnetic characterization and element-selective hysteresis loops obtained by x-ray magnetic circular dichroism (XMCD) reveal a strong exchange coupling between the core and the shell which results in homogeneous loops with moderate coercivity. Moreover, the magnetic properties can be tuned by controlling the core diameter or shell thickness. However, the results depend only weakly on the hard/soft or inverse soft/hard morphology.

Nogues, Josep

2013-03-01

11

Evolution of Titan's outer icy shell: Role of ocean crystallization and surface weathering  

NASA Astrophysics Data System (ADS)

The Cassini-Huygens mission has brought evidences for an internal ocean lying under an outer ice shell. The structure and evolution of the outer ice shell and of the internal ocean are essential to understand Titan's surface morphology as well as its atmosphere evolution. The observed shape and the gravity field of Titan provide information on the present-day structure of the H2O mantle, in terms of ocean/ice interface depth and crustal density. By modeling consistently topography and gravity data, we have quantified the amplitudes of ice shell thickness and/or crustal density variations. Moreover, we have constrained the possible viscosity structure of the outer shell and thermal gradients by modeling the topography relaxation rate. Lateral variations in the thickness of the outer ice shell may be explained by heterogeneous ocean crystallization, while surface weathering by liquid hydrocarbons may generate surface erosion and crustal alteration. To determine how these processes affect Titan's dynamics, we model heat and mass transfers between the internal ocean, the ice shell and the atmosphere and we determine the time evolution of long-wavelength topography and surface stress patterns for different evolutionary scenarios. Finally, we compare our predicted maps of surface stress and heat flux anomalies with the global repartition of the morphological features observed by VIMS and Radar.

Lefevre, A.; Tobie, G.; Amit, H.; Cadek, O.; Choblet, G.; Le Mouelic, S.; Mitri, G.; Sotin, C.

2013-12-01

12

Detecting the Rapidly Expanding Outer Shell of the Crab Nebula: Where to Look  

NASA Astrophysics Data System (ADS)

We present a range of steady-state photoionization simulations, corresponding to different assumed shell geometries and compositions, of the unseen postulated rapidly expanding outer shell to the Crab Nebula. The properties of the shell are constrained by the mass that must lie within it, and by limits to the intensities of hydrogen recombination lines. In all cases the photoionization models predict very strong emissions from high ionization lines that will not be emitted by the Crab's filaments, alleviating problems with detecting these lines in the presence of light scattered from brighter parts of the Crab. The near-NIR [Ne VI] ?7.652 ?m line is a particularly good case; it should be dramatically brighter than the optical lines commonly used in searches. The C IV ?1549 doublet is predicted to be the strongest absorption line from the shell, which is in agreement with Hubble Space Telescope observations. We show that the cooling timescale for the outer shell is much longer than the age of the Crab, due to the low density. This means that the temperature of the shell will actually "remember" its initial conditions. However, the recombination time is much shorter than the age of the Crab, so the predicted level of ionization should approximate the real ionization. In any case, it is clear that IR observations present the best opportunity to detect the outer shell and so guide future models that will constrain early events in the original explosion.

Wang, Xiang; Ferland, G. J.; Baldwin, J. A.; Loh, E. D.; Richardson, C. T.

2013-09-01

13

DETECTING THE RAPIDLY EXPANDING OUTER SHELL OF THE CRAB NEBULA: WHERE TO LOOK  

SciTech Connect

We present a range of steady-state photoionization simulations, corresponding to different assumed shell geometries and compositions, of the unseen postulated rapidly expanding outer shell to the Crab Nebula. The properties of the shell are constrained by the mass that must lie within it, and by limits to the intensities of hydrogen recombination lines. In all cases the photoionization models predict very strong emissions from high ionization lines that will not be emitted by the Crab's filaments, alleviating problems with detecting these lines in the presence of light scattered from brighter parts of the Crab. The near-NIR [Ne VI] {lambda}7.652 {mu}m line is a particularly good case; it should be dramatically brighter than the optical lines commonly used in searches. The C IV {lambda}1549 doublet is predicted to be the strongest absorption line from the shell, which is in agreement with Hubble Space Telescope observations. We show that the cooling timescale for the outer shell is much longer than the age of the Crab, due to the low density. This means that the temperature of the shell will actually ''remember'' its initial conditions. However, the recombination time is much shorter than the age of the Crab, so the predicted level of ionization should approximate the real ionization. In any case, it is clear that IR observations present the best opportunity to detect the outer shell and so guide future models that will constrain early events in the original explosion.

Wang Xiang; Ferland, G. J. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Baldwin, J. A.; Loh, E. D.; Richardson, C. T., E-mail: xiang.wang@uky.edu [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-2320 (United States)

2013-09-10

14

Polymeric micelles possessing polyethyleneglycol as outer shell and their unique behaviors in accelerated blood clearance phenomenon.  

PubMed

Polymeric micelles are assemblies of synthetic polymers and have been studied and developed as drug carriers for targeting. Polymeric micelles are composed of the inner core and the outer shell, and typically form from AB-type block copolymers in which two polymer blocks are connected in a tandem form. Polyethyleneglycol (PEG) has been most commonly used as one polymer block composing the outer shell. This review describes the reasons that PEG is used for the outer shell of the polymeric micelle carrier systems. On the other hand, accelerated blood clearance (ABC) phenomenon is a well-known immunological response of PEG-coated liposomes. Since the ABC phenomenon greatly influences targeting functions of carrier systems, elaborative studies on polymeric micelles' ABC phenomenon have been done, and revealed different behaviors of the polymeric micelle systems from those of PEG-coated liposomes. These studies indicate that polymeric micelle systems are highly feasible tools for contrast agent targeting as well as theranostics. PMID:23727909

Shiraishi, Kouichi; Yokoyama, Masayuki

2013-01-01

15

Preliminary engineering studies for the support shell of the outer tracker of the SDC detector  

SciTech Connect

The Solenoidal Detector Collaboration (SDC) detector is in the conceptual design phase. ORNL is currently working with various sub-groups on the design of the outer tracker portion of the SDC detector. A major focus in the outer tracker design is the structure that mounts and supports the tracking elements. This structure must meet extreme requirements of alignment and stability while containing a minimum of material. This report describes the requirements, evaluations, and analyses that have been performed on the two options being explored; a cylindrical support shell and a modular support shell.

Vandergriff, D.H.; Mayhall, J.

1991-09-01

16

Electronic transport properties of inner and outer shells in near ohmic-contacted double-walled carbon nanotube transistors  

NASA Astrophysics Data System (ADS)

We investigate electronic transport properties of field-effect transistors based on double-walled carbon nanotubes, of which inner shells are metallic and outer shells are semiconducting. When both shells are turned on, electron-phonon scattering is found to be the dominant phenomenon. On the other hand, when outer semiconducting shells are turned off, a zero-bias anomaly emerges in the dependence of differential conductance on the bias voltage, which is characterized according to the Tomonaga-Luttinger liquid model describing tunneling into one-dimensional materials. We attribute these behaviors to different contact conditions for outer and inner shells of the double-walled carbon nanotubes. A simple model combining Luttinger liquid model for inner metallic shells and electron-phonon scattering in outer semiconducting shells is given here to explain our transport data at different temperatures.

Zhang, Yuchun; Zhou, Liyan; Zhao, Shangqian; Wang, Wenlong; Wang, Enge; Liang, Wenjie

2014-06-01

17

Hard Clam, 'Mercenaria mercenaria': Shell Growth Patterns in Chesapeake Bay.  

National Technical Information Service (NTIS)

Dark bands in the middle honogeneous layer of Mercanaria mercenaria shells, formed each summer and early fall in lower Chesapeake Bay experimental and wild populations, were used to determine age. Distinct growth cessation marks caused by low winter water...

L. W. Fritz D. S. Haven

1983-01-01

18

Effect of magnesium stearate or calcium stearate as additives on dissolution profiles of diltiazem hydrochloride from press-coated tablets with hydroxypropylmethylcellulose acetate succinate in the outer shell.  

PubMed

Effect of magnesium stearate (MgSt) or calcium stearate (CaSt) on the dissolution profiles of diltiazem hydrochloride in the core of press-coated (PC) tablets with an outer shell composed of hydroxypropylmethylcellulose acetate succinate (HPMCAS) was evaluated by porosity and changes in IR spectra of tablets. In JP first fluid (pH 1.2), the lag time increased with decreasing porosity and was greatest by the addition of MgSt to HPMCAS. While, in JP second fluid (pH 6.8), it increased with decreasing porosity by the addition of CaSt, but hardly changed by the addition of MgSt. Thus, using tablets prepared with the same composition as the outer shell, the changes in IR spectra and uptake amount of the dissolution media after immersion in first fluid and second fluid were determined. The results suggested that some physicochemical interaction occur between MgSt and HPMCAS in tablets with HPMCAS and MgSt and the uptake increased markedly in each dissolution medium. These phenomena seem to cause a prolongation of lag time in first fluid but a shortening of it in second fluid in PC tablets with HPMCAS and MgSt. In contrast, CaSt and HPMCAS did not show such interactions and increased the hydrophobic properties of the outer shell. Consequently, the lag time was only slightly prolonged in first fluid, however, markedly prolonged in second fluid due to suppression of second fluid penetration into micro pores in the outer shell and HPMCAS gel formation on the surface in PC tablets with HPMCAS and CaSt. PMID:11274815

Fukui, E; Miyamura, N; Kobayashi, M

2001-03-23

19

Mutation of outer-shell residues modulates metal ion co-ordination strength in a metalloenzyme.  

PubMed

The metal ion co-ordination sites of many metalloproteins have been characterized by a variety of spectroscopic techniques and small-molecule model systems, revealing many important insights into the structural determinants of metal ion co-ordination. However, our understanding of this fundamentally and practically important phenomenon remains frustratingly simplistic; in many proteins it is essentially impossible to predict metal ion specificity and the effects of remote 'outer-shell' residues on metal ion co-ordination strength are also poorly defined. This is exemplified by our inability to explain why metalloenzymes with identical metal ion co-ordination spheres, such as the closely related orthologues of bacterial PTE (phosphotriesterase) from Agrobacterium radiobacter and Pseudomonas diminuta, display different metal ion specificity and co-ordination strength. In the present study, we present a series of PTE variants that all possess identical metal ion co-ordination spheres, yet display large differences in their metal ion co-ordination strength. Using measurement of the rates of metal ion dissociation from the active site alongside analysis of structural data obtained through X-ray crystallography, we show that 'outer-shell' residues provide essential support for the metal ion ligands, in effect buttressing them in their optimal orientation. Remote mutations appear to modulate metal ion interactions by increasing or decreasing the stabilizing effects of these networks. The present study therefore provides a description of how the greater protein fold can be modified to 'tune' the strength of metal ion co-ordination and metal ion specificity, as well as reinforcing the concept of proteins as ensembles of conformational states with unique structures and biochemical properties. PMID:20459397

Foo, Jee-Loon; Jackson, Colin J; Carr, Paul D; Kim, Hye-Kyung; Schenk, Gerhard; Gahan, Lawrence R; Ollis, David L

2010-07-15

20

Hard shell gas-filled contrast enhancement particles for colour Doppler ultrasound imaging of tumors†  

PubMed Central

Hollow hard shell particles of 200 nm and 2 micron diameter with a 10 nm thick porous silica shell have been synthesized using polystyrene templates and a sol–gel process. The template ensures than the hollow particles are monodispersed, while the charged silica surface ensures that they remain suspended in solution for weeks. When filled with perfluorocarbon gas, the particles behave as an efficient contrast agent for colour Doppler ultrasound imaging in human breast tissue. The silica shell provides unique properties compared to conventional soft shell particles employed as ultrasound contrast agents: uniform size control, strong adsorption to tissue and cells immobilizing particles at the tissue injection site, a long imaging lifetime, and a silica surface that can be easily modified with biotargeting ligands or small molecules to adjust the surface charge and polarity.

Martinez, H. Paul; Kono, Yuko; Blair, Sarah L.; Sandoval, Sergio; Wang-Rodriguez, Jessica

2011-01-01

21

Robust antiferromagnetic coupling in hard-soft bi-magnetic core/shell nanoparticles  

NASA Astrophysics Data System (ADS)

The growing miniaturization demand of magnetic devices is fuelling the recent interest in bi-magnetic nanoparticles as ultimate small components. One of the main goals has been to reproduce practical magnetic properties observed so far in layered systems. In this context, although useful effects such as exchange bias or spring magnets have been demonstrated in core/shell nanoparticles, other interesting key properties for devices remain elusive. Here we show a robust antiferromagnetic (AFM) coupling in core/shell nanoparticles which, in turn, leads to the foremost elucidation of positive exchange bias in bi-magnetic hard-soft systems and the remarkable regulation of the resonance field and amplitude. The AFM coupling in iron oxide—manganese oxide based, soft/hard and hard/soft, core/shell nanoparticles is demonstrated by magnetometry, ferromagnetic resonance and X-ray magnetic circular dichroism. Monte Carlo simulations prove the consistency of the AFM coupling. This unique coupling could give rise to more advanced applications of bi-magnetic core/shell nanoparticles.

Estrader, M.; López-Ortega, A.; Estradé, S.; Golosovsky, I. V.; Salazar-Alvarez, G.; Vasilakaki, M.; Trohidou, K. N.; Varela, M.; Stanley, D. C.; Sinko, M.; Pechan, M. J.; Keavney, D. J.; Peiró, F.; Suriñach, S.; Baró, M. D.; Nogués, J.

2013-12-01

22

Robust antiferromagnetic coupling in hard-soft bi-magnetic core/shell nanoparticles.  

PubMed

The growing miniaturization demand of magnetic devices is fuelling the recent interest in bi-magnetic nanoparticles as ultimate small components. One of the main goals has been to reproduce practical magnetic properties observed so far in layered systems. In this context, although useful effects such as exchange bias or spring magnets have been demonstrated in core/shell nanoparticles, other interesting key properties for devices remain elusive. Here we show a robust antiferromagnetic (AFM) coupling in core/shell nanoparticles which, in turn, leads to the foremost elucidation of positive exchange bias in bi-magnetic hard-soft systems and the remarkable regulation of the resonance field and amplitude. The AFM coupling in iron oxide-manganese oxide based, soft/hard and hard/soft, core/shell nanoparticles is demonstrated by magnetometry, ferromagnetic resonance and X-ray magnetic circular dichroism. Monte Carlo simulations prove the consistency of the AFM coupling. This unique coupling could give rise to more advanced applications of bi-magnetic core/shell nanoparticles. PMID:24343382

Estrader, M; López-Ortega, A; Estradé, S; Golosovsky, I V; Salazar-Alvarez, G; Vasilakaki, M; Trohidou, K N; Varela, M; Stanley, D C; Sinko, M; Pechan, M J; Keavney, D J; Peiró, F; Suriñach, S; Baró, M D; Nogués, J

2013-01-01

23

Structure and dynamics of Titan’s outer icy shell constrained from Cassini data  

NASA Astrophysics Data System (ADS)

The Cassini-Huygens mission has brought evidence for an internal ocean lying beneath an outer icy shell on Titan. The observed topography differs significantly from the reference hydrostatic shape, while the measured geoid anomalies (estimated up to degree three) remain weak. This suggests compensation either by deflections of the ocean/ice interface or by density variations in an upper crust. However, the observed degree-three gravity signal indicates either that the topography is not perfectly compensated, or that mass anomalies exist in the deep interior, or a combination of both. To investigate the compensation mechanisms, we developed an interior structure model satisfying simultaneously the surface gravity and long-wavelength topography. We quantified the excess deflection of ocean/ice I interface, the density anomalies in the upper crust, or the deflection of the ice/rock interface needed to explain the observed degree-three anomalies. Finally, we tested the long-term mechanical stability of the internal mass anomalies by computing the relaxation rate of each internal interface in response to interface mass load. We showed that the computed deflection of the ocean/ice I interface is stable only for a conductive highly viscous layer above a relatively cold ocean (T < 250 K). Solutions with a moderately convecting ice shell are possible only for models with crustal density variations. Due to fast relaxation, the high pressure ice layer cannot be the source of the degree three geoid anomalies. The existence of mass anomalies in the rocky core remains a possible explanation. Estimation of the degree-four gravity signal by future Cassini flybys will further constrain the compensation mechanism and the source of gravity anomalies.

Lefevre, Axel; Tobie, Gabriel; Choblet, Gaël; ?adek, Ond?ej

2014-07-01

24

Triple assembly of ZnO, large-scale hollow spherical shells with flower-like species consisting of rods grown on the outer surfaces of shells  

SciTech Connect

Novel large-scale hollow ZnO spherical shells were synthesized by ionic liquids assisted hydrothermal oxidization of pure zinc powder without any catalyst at a relatively low temperature of 160 deg. C. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) patterns show that the shells are composed of ZnO and the structure of the shells is very unique. Textured flower-like ZnO consisting of ZnO rods is grown on the outer surfaces of shells forming a triple assembly. Room-temperature photoluminescence spectra of the oxidized material show a sharp peak at 379 nm and a wider broad peak centered at 498 nm. The possible growth mechanism of the triple assembly of ZnO is discussed in detail. - Graphical abstract: A proposed growth mechanism of large scale hollow ZnO. Bubbles provide the aggregation center for ionic liquids that leads to the formation of hollow Zn particle-dotted shells, buoyancy promotes shells to go upward, the breach occurs when shells are subjected to overpressure.

Shang Yazhuo; Hu Jun [Key Laboratory for Advanced Materials, East China University of Science and Technology, Shanghai, 200237 (China); Liu Honglai, E-mail: yazhuoshang@ecust.edu.c [Key Laboratory for Advanced Materials, East China University of Science and Technology, Shanghai, 200237 (China); Hu Ying [Key Laboratory for Advanced Materials, East China University of Science and Technology, Shanghai, 200237 (China)

2010-03-15

25

Percolative properties of hard oblate ellipsoids of revolution with a soft shell.  

PubMed

We present an in-depth analysis of the geometrical percolation behavior in the continuum of random assemblies of hard oblate ellipsoids of revolution. Simulations were carried out by considering a broad range of aspect ratios, from spheres up to aspect-ratio-100 platelike objects, and with various limiting two-particle interaction distances, from 0.05 times the major axis up to 4.0 times the major axis. We confirm the widely reported trend of a consistent lowering of the hard particle critical volume fraction with increase of the aspect ratio. Moreover, by assimilating the limiting interaction distance to a shell of constant thickness surrounding the ellipsoids, we propose a simple relation based on the total excluded volume of these objects which allows us to estimate the critical concentration from a quantity that is quasi-invariant over a large spectrum of limiting interaction distances. Excluded volume and volume quantities are derived explicitly. PMID:19256821

Ambrosetti, Gianluca; Johner, Niklaus; Grimaldi, Claudio; Danani, Andrea; Ryser, Peter

2008-12-01

26

Percolative properties of hard oblate ellipsoids of revolution with a soft shell  

NASA Astrophysics Data System (ADS)

We present an in-depth analysis of the geometrical percolation behavior in the continuum of random assemblies of hard oblate ellipsoids of revolution. Simulations were carried out by considering a broad range of aspect ratios, from spheres up to aspect-ratio-100 platelike objects, and with various limiting two-particle interaction distances, from 0.05 times the major axis up to 4.0 times the major axis. We confirm the widely reported trend of a consistent lowering of the hard particle critical volume fraction with increase of the aspect ratio. Moreover, by assimilating the limiting interaction distance to a shell of constant thickness surrounding the ellipsoids, we propose a simple relation based on the total excluded volume of these objects which allows us to estimate the critical concentration from a quantity that is quasi-invariant over a large spectrum of limiting interaction distances. Excluded volume and volume quantities are derived explicitly.

Ambrosetti, Gianluca; Johner, Niklaus; Grimaldi, Claudio; Danani, Andrea; Ryser, Peter

2008-12-01

27

Outer Electrospun Polycaprolactone Shell Induces Massive Foreign Body Reaction and Impairs Axonal Regeneration through 3D Multichannel Chitosan Nerve Guides  

PubMed Central

We report on the performance of composite nerve grafts with an inner 3D multichannel porous chitosan core and an outer electrospun polycaprolactone shell. The inner chitosan core provided multiple guidance channels for regrowing axons. To analyze the in vivo properties of the bare chitosan cores, we separately implanted them into an epineural sheath. The effects of both graft types on structural and functional regeneration across a 10?mm rat sciatic nerve gap were compared to autologous nerve transplantation (ANT). The mechanical biomaterial properties and the immunological impact of the grafts were assessed with histological techniques before and after transplantation in vivo. Furthermore during a 13-week examination period functional tests and electrophysiological recordings were performed and supplemented by nerve morphometry. The sheathing of the chitosan core with a polycaprolactone shell induced massive foreign body reaction and impairment of nerve regeneration. Although the isolated novel chitosan core did allow regeneration of axons in a similar size distribution as the ANT, the ANT was superior in terms of functional regeneration. We conclude that an outer polycaprolactone shell should not be used for the purpose of bioartificial nerve grafting, while 3D multichannel porous chitosan cores could be candidate scaffolds for structured nerve grafts.

Behrens, Peter; Wienecke, Soenke; Chakradeo, Tanmay; Glasmacher, Birgit

2014-01-01

28

Outer Electrospun Polycaprolactone Shell Induces Massive Foreign Body Reaction and Impairs Axonal Regeneration through 3D Multichannel Chitosan Nerve Guides.  

PubMed

We report on the performance of composite nerve grafts with an inner 3D multichannel porous chitosan core and an outer electrospun polycaprolactone shell. The inner chitosan core provided multiple guidance channels for regrowing axons. To analyze the in vivo properties of the bare chitosan cores, we separately implanted them into an epineural sheath. The effects of both graft types on structural and functional regeneration across a 10?mm rat sciatic nerve gap were compared to autologous nerve transplantation (ANT). The mechanical biomaterial properties and the immunological impact of the grafts were assessed with histological techniques before and after transplantation in vivo. Furthermore during a 13-week examination period functional tests and electrophysiological recordings were performed and supplemented by nerve morphometry. The sheathing of the chitosan core with a polycaprolactone shell induced massive foreign body reaction and impairment of nerve regeneration. Although the isolated novel chitosan core did allow regeneration of axons in a similar size distribution as the ANT, the ANT was superior in terms of functional regeneration. We conclude that an outer polycaprolactone shell should not be used for the purpose of bioartificial nerve grafting, while 3D multichannel porous chitosan cores could be candidate scaffolds for structured nerve grafts. PMID:24818158

Duda, Sven; Dreyer, Lutz; Behrens, Peter; Wienecke, Soenke; Chakradeo, Tanmay; Glasmacher, Birgit; Haastert-Talini, Kirsten

2014-01-01

29

Collision safety of a hard-shell low-mass vehicle  

SciTech Connect

Low-mass vehicles and in particular low-mass electric vehicles as produced today in very small quantities are in general not designed for crashworthiness in collisions. Particular problems of compact low-mass cars are: reduced length of the car front, low mass compared to other vehicles, and heavy batteries in the case of an electric car. With the intention of studying design improvements, three frontal crash tests were run last year: the first one with a commercial, lightweight electric car; the second with a reinforced version of the same car; and the last one with a car based on a different structural design with a `hard-shell` car body. Crash tests showed that the latter solution made better use of the small zone available for continuous energy absorption. The paper discusses further the problem of frontal collisions between vehicles of different weight and, in particular, the side collision. A side-collision test was run with the hard-shell vehicle following the ECE lateral-impact test procedure at 50 km/h and led to results for the EuroSIDI-dummy well below current injury tolerance criteria.

Kaeser, R.; Walz, F.H.; Brunner, A.

1994-06-01

30

Semi-wild chimpanzees open hard-shelled fruits differently across communities.  

PubMed

Researchers investigating the evolutionary roots of human culture have turned to comparing behaviours across nonhuman primate communities, with tool-based foraging in particular receiving much attention. This study examined whether natural extractive foraging behaviours other than tool selection differed across nonhuman primate colonies that had the same foods available. Specifically, the behaviours applied to open the hard-shelled fruits of Strychnos spp. were examined in three socially separate, semi-wild colonies of chimpanzees (Pan troglodytes) that lived under shared ecological conditions at Chimfunshi Wildlife Orphanage, and were comparable in their genetic makeup. The chimpanzees (N = 56) consistently applied six techniques to open these fruits. GLMM results revealed differences in the number of combined technique types to open fruits across the colonies. They also showed colony differences in the application of three specific techniques. Two techniques (full biting and fruit cracking) were entirely absent in some colonies. This study provides empirical evidence that natural hard-shelled fruit-opening behaviours are distinct across chimpanzee colonies, differences that most likely have not resulted from ecological and genetic reasons. PMID:24337784

Rawlings, Bruce; Davila-Ross, Marina; Boysen, Sarah T

2014-07-01

31

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

32

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

33

Antibonding. beta. * valence MOs in the inner-shell and outer-shell spectra of the fluorobenzenes  

SciTech Connect

Electron transmission, inner-shell electron energy loss and magnetic circular dichroism spectra have been analyzed in an effort to trace the positions of the sigma* antibonding valence MOs in benzene and its fluorinated derivatives. The correlation of negative-ion resonances in these systems shows clearly that a sigma* valence level descends with increasing fluorination so as to become the lowest virtual MO in hexafluorobenzene. In addition to the low-lying sigma* negative-ion shape resonances, several negative-ion Feshbach resonances are identified as involving 3s and 3p Rydberg orbitals. The carbon K-shell spectra of benzene and its fluorinated derivatives below the respective C 1s ionization potentials are dominated by excitations to 1..pi..* and 2..pi..* valence levels. A systematic shift of the sigma* levels to lower energy with increasing fluorination is observed which is consistent with the perfluoro effect. Resonances terminating at sigma*(C-C) are found to dominate the C 1s near continuum, with dramatic enhancement of these transitions in the more highly fluorinated species. Investigation of hexafluoro- and 1,2,4,5-tetrafluorobenzene by vacuum-ultraviolet magnetic circular dichroism in the vapor phase confirms the presence of bands which are not ..pi.. ..-->.. ..pi..*. Once again, low-lying sigma* MOs are invoked as terminating orbitals.

Hitchcock, A.P.; Fischer, P.; Gedanken, A.; Robin, M.B.

1987-01-29

34

In vitro Release Characteristics of Hard Shell Capsule Products Coated with Aqueous and Organic-Based Enteric Polymers  

Microsoft Academic Search

In this article, an overview of the rationale for the use of enteric coated (EC) dosage forms is presented. The benefits and disadvantages inherent in the use of aqueous dispersions and organic solutions of the various polymers to generate these products are discussed. The comparative dissolution stability of a hard shell capsule product coated with enteric polymers applied as either

K. S. Murthy; Daniel A. Kubert; Mahdi B. Fawzi

1988-01-01

35

The influence of pellet shape and film coating on the filling of pellets into hard shell capsules  

Microsoft Academic Search

Pellets of different shape, varying from spherical to cylindrical, were filled into hard shell capsules. When no film coat was applied, the pellets had not to be perfectly spherical in order to be filled reproducibly. An aspect ratio of 1.2 or less appeared to be the threshold value. However, pronounced surface roughness hindered the filling process, and hence it appears

Ranjana Chopra; Fridrun Podczeck; J. Michael Newton; Göran Alderborn

2002-01-01

36

Flexural models of trench/outer rise topography of coronae on Venus with axisymmetric spherical shell elastic plates  

NASA Technical Reports Server (NTRS)

Magellan altimetry has revealed that many coronae on Venus have trenches or moats around their peripheries and rises outboard of the trenches. This trench/outer rise topographic signature is generally associated with the tectonic annulus of the corona. Sandwell and Schubert have interpreted the trench/outer rise topography and the associated tectonic annulus around coronae to be the result of elastic bending of the Venus lithosphere (though the tectonic structures are consequences of inelastic deformation of the lithosphere). They used two-dimensional elastic plate flexure theory to fit topographic profiles across a number of large coronae and inferred elastic lithosphere thicknesses between about 15 and 40 km, similar to inferred values of elastic thickness for the Earth's lithosphere at subduction zones around the Pacific Ocean. Here, we report the results of using axisymmetric elastic flexure theory for the deformation of thin spherical shell plates to interpret the trench/outer rise topography of the large coronae modeled by Sandwell and Schubert and of coronae as small as 250 km in diameter. In the case of a corona only a few hundred kilometers in diameter, the model accounts for the small planform radius of the moat and the nonradial orientation of altimetric traces across the corona. By fitting the flexural topography of coronae we determine the elastic thickness and loading necessary to account for the observed flexure. We calculate the associated bending moment and determine whether the corona interior topographic load can provide the required moment. We also calculate surface stresses and compare the stress distribution with the location of annular tectonic features.

Moore, W.; Schubert, Gerald; Sandwell, David T.

1992-01-01

37

Vibration of a single microcapsule with a hard plastic shell in an acoustic standing wave field.  

PubMed

Observation techniques for measuring the small vibration of a single microcapsule of tens of nanometers in an acoustic standing wave field are discussed. First, simultaneous optical observation of a microbubble vibration by two methods is investigated, using a high-speed video camera, which permits two-dimensional observation of the bubble vibration, and a laser Doppler vibrometer (LDV), which can observe small bubble vibration amplitudes at high frequency. Bubbles of tens of micrometers size were trapped at the antinode of an acoustic standing wave generated in an observational cell. Bubble vibration at 27 kHz could be observed and the experimental results for the two methods showed good agreement. The radial vibration of microcapsules with a hard plastic shell was observed using the LDV and the measurement of the capsule vibration with radial oscillation amplitude of tens of nanometers was successful. The acoustic radiation force acting on microcapsules in the acoustic standing wave was measured from the trapped position of the standing wave and the radial oscillation amplitude of the capsules was estimated from the theoretical equation of the acoustic radiation force, giving results in good agreement with the LDV measurements. The radial oscillation amplitude of a capsule was found to be proportional to the amplitude of the driving sound pressure. A larger expansion ratio was observed for capsules closer to the resonance condition under the same driving sound pressure and frequency. PMID:21507751

Koyama, Daisuke; Kotera, Hironori; Kitazawa, Natsuko; Yoshida, Kenji; Nakamura, Kentaro; Watanabe, Yoshiaki

2011-04-01

38

Thermodynamic functions and phase diagram of water and high-pressure ices: Implication to an outer water-ice shell of Ganymede  

Microsoft Academic Search

Water and water ice are important components of many space objects. Astrophysical and spectroscopic research shows that Solar system giant planets' satellites (Europa, Ganymede, Callisto, Titan & Enceladus), small transneptunian planets, asteroids and comets contain considerable amount of water and ice. «Galileo» and «Cassini-Huygens» missions show that liquid water could possibly exist under outer ice shells of Jupiter and Saturn

Dmitry Antsyshkin; Anna Dunaeva; Oleg Kuskov

2010-01-01

39

An in vitro investigation of the suitability of press-coated tablets with hydroxypropylmethylcellulose acetate succinate (HPMCAS) and hydrophobic additives in the outer shell for colon targeting  

Microsoft Academic Search

To develop a new colon targeting formulation, which can suppress drug release completely during 12 h in the stomach and release the drug rapidly after a lag time of 3±1 h in the small intestine, the use of press-coated tablets with hydroxypropylmethylcellulose acetate succinate (HPMCAS) in the outer shell was investigated. The release of diltiazem hydrochloride (DIL) as a model

Eiji Fukui; Nobuteru Miyamura; Masao Kobayashi

2001-01-01

40

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

2013-10-01

41

A DETAILED KINEMATIC MAP OF CASSIOPEIA A'S OPTICAL MAIN SHELL AND OUTER HIGH-VELOCITY EJECTA  

SciTech Connect

We present three-dimensional (3D) kinematic reconstructions of optically emitting material in the young Galactic supernova remnant Cassiopeia A (Cas A). These Doppler maps have the highest spectral and spatial resolutions of any previous survey of Cas A and represent the most complete catalog of its optically emitting material to date. We confirm that the bulk of Cas A's optically bright ejecta populate a torus-like geometry tilted approximately 30 Degree-Sign with respect to the plane of the sky with a -4000 to +6000 km s{sup -1} radial velocity asymmetry. Near-tangent viewing angle effects and an inhomogeneous surrounding circumstellar material/interstellar medium environment suggest that this geometry and velocity asymmetry may not be faithfully representative of the remnant's true 3D structure or the kinematic properties of the original explosion. The majority of the optical ejecta are arranged in several well-defined and nearly circular ring-like structures with diameters between approximately 30'' (0.5 pc) and 2' (2 pc). These ejecta rings appear to be a common phenomenon of young core-collapse remnants and may be associated with post-explosion input of energy from plumes of radioactive {sup 56}Ni-rich ejecta that rise, expand, and compress non-radioactive material. Our optical survey encompasses Cas A's faint outlying ejecta knots and exceptionally high-velocity NE and SW streams of S-rich debris often referred to as ''jets''. These outer knots, which exhibit a chemical make-up suggestive of an origin deep within the progenitor star, appear to be arranged in opposing and wide-angle outflows with opening half-angles of Almost-Equal-To 40 Degree-Sign.

Milisavljevic, Dan [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, 02138 (United States); Fesen, Robert A., E-mail: dmilisav@cfa.harvard.edu [6127 Wilder Lab, Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States)

2013-08-01

42

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 500 N 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±0.26 N for hypromellose capsules and 4.54±0.26 N 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

2013-11-18

43

Dynamical behavior caused by numerical dynamo simulations in a rotating spherical shell with the heterogeneous outer boundary  

NASA Astrophysics Data System (ADS)

We use numerical dynamo simulations in a rotating spherical shell to investigate the thermal structure in the core influenced by the heterogeneous top boundary. The experimental study in a rotating hemispherical shell with huge anomalous heterogeneous outer boundary suggested that the ';front' structure caused by huge amplitude of thermal anomalies at the top boundary but not checked in the various dynamo regimes [Sumita and Olson, 2002], which predicted that the major physical mechanism for the ';front' structure could be understood by the thermal wind balance. Aurnou and Aubert [2011] suggested that there would be several regimes when the heterogeneous condition at the top boundary was imposed in numerical dynamo simulations but not investigated thermal structure in the core to check the experimental consequences as well as the regime transition between convective and boundary modulated dynamo regimes. Here we use two Ekman number (10^-4 and 3x10^-5) and fixed magnetic and thermal Prandtl number (the unity) with varying various Rayleigh number defined the amplitude of lateral variation of heat flux across the top boundary. The pattern of heterogeneous boundary condition is used as (l,m)=(2,2). The two or more ';fronts' are found in imposed heterogeneous boundary at least. These fronts are very small time-dependence for their positions with large lateral temperature variations near fronts. This means that the ';front' structure could be found in the MHD dynamo system as well as non-magnetic cases shown in Sumita and Olson [2002] because the Lorentz force contribution to thermal wind balance seems to be very weak compared to the buoyancy flux to balance the Coriolis effect. More information will be provided in the presentation.

Nakagawa, T.; Aubert, J.

2013-12-01

44

Oxygen and Carbon Stable Isotope and Sr:Ca Records in Outer and Middle Microstructural Layers of Bivalve Shells (Mercenaria campechiensis)  

NASA Astrophysics Data System (ADS)

? 18O, ? 13C, and Sr:Ca records contained in the aragonitic shells of the northern and southern quahogs (Mercenaria mercenaria and M. campechiensis, respectively) have been used in paleoclimate and paleoecological studies, although these environmental proxies have not yet been calibrated. Early geochemical studies of quahog shells focused on the outer prismatic layer. Because of innovations in microsampling techniques, recent studies focus on the middle cross-lamellar layer, providing high temporal resolution. Do both microstructural layers record similar profiles of ? 18O, ? 13C, and Sr:Ca? If not, which layer more faithfully records ambient conditions? Here, we provide a preliminary calibration of ? 18O and ? 13C using shells of M. campechiensis and test the hypothesis that both microstructural layers record similar geochemical information. Quahogs were collected alive near Bokeelia, SW Florida. The USGS maintained fortnightly to monthly temperature and salinity records at this site. These data, together with mixing equations of ? 18OWATER- and ? 13CDIC-salinity, were used to construct predictive model shells. The last 2 years of shell growth were sampled at 0.1-0.5 mm intervals yielding ˜100 ? g of material that was split for isotopic and elemental analyses. Comparison of model and observed shells reveals a predictable offset in ? 18O, where the model is offset by +1.3‰ relative to the observed shell. When corrected for the offset, ? 18O shell closely matches the model. Values range from -2.5 to +2‰ . Profiles of ? 18O from outer and middle layers are nearly identical. ? 13C of the middle layer is more variable and can be as much as 2.4‰ more positive than the outer layer. Observed ? 13C in the middle layer follows the general trend of the model, but winter-spring shell growth is offset by -1.7‰ relative to the model. Sr:Ca ratios from the middle layer can be as much as 0.4 mmol/mol higher than the outer layer. We conclude that either microstructural layer can be used to study variation in ? 18O because both layers preserve nearly identical profiles. Observed offsets in ? 13C and Sr:Ca ratios between microstructural layers can potentially complicate calibration and environmental/ climate reconstructions. The next phase of our research is to understand the mechanisms that control these offsets and determine which microstructural layer is better suited for geochemical study.

Surge, D.; Owens, S.

2003-12-01

45

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

46

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

47

The influence of pellet shape and film coating on the filling of pellets into hard shell capsules.  

PubMed

Pellets of different shape, varying from spherical to cylindrical, were filled into hard shell capsules. When no film coat was applied, the pellets had not to be perfectly spherical in order to be filled reproducibly. An aspect ratio of 1.2 or less appeared to be the threshold value. However, pronounced surface roughness hindered the filling process, and hence it appears necessary to monitor this parameter. After coating of the pellets with an ethylcellulose film, none of the batches could be filled to an acceptable standard, because electrostatic loading led to a blockage of the filling mechanism. However, the addition of 1% talcum powder was sufficient to remove all charges, and again filling became a function of the pellet shape, confirming the threshold aspect ratio value of 1.2. PMID:11976021

Chopra, Ranjana; Podczeck, Fridrun; Newton, J Michael; Alderborn, Göran

2002-05-01

48

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

2010-10-15

49

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

50

Temporal variations of the outer atmosphere and the dust shell of the carbon-rich Mira variable V Ophiuchi probed with VLTI/MIDI  

NASA Astrophysics Data System (ADS)

Aims:We present the first multi-epoch N-band spectro-interferometric observations of the carbon-rich Mira variable V Oph using MIDI at the ESO's Very Large Telescope Interferometer. Our aim is to study temporal variations of physical properties of the outer atmosphere and the circumstellar dust shell based on spectrally-dispersed N-band visibilities over the C2H2 (+HCN) features and the dust emission. Methods: Our MIDI observations were carried out at three different phases 0.18, 0.49, and 0.65, with three different baselines (projected baseline lengths of 42-124 m) using four 8.2 m Unit Telescopes (UT2-UT4, UT1-UT4, and UT2-UT3 baseline configurations). Results: The wavelength dependence of the uniform-disk diameters obtained at all epochs is characterized by a roughly constant region between 8 and 10 ?m with a slight dip centered at 9.5 ?m and a gradual increase longward of 10 ?m. These N-band angular sizes are significantly larger than the estimated photospheric size of V Oph. The angular sizes observed at different epochs reveal that the object appears smaller at phase 0.49 (minimum light) with uniform-disk diameters of 5-12 mas than at phases 0.18 ( 12-20 mas) and 0.65 ( 9-15 mas). We interpret these results with a model consisting of optically thick C2H2 layers and an optically thin dust shell. Our modeling suggests that the C2H2 layers around V Oph are more extended ( 1.7-1.8 Rstar) at phases 0.18 and 0.65 than at phase 0.49 ( 1.4 Rstar) and that the C2H2 column densities appear to be the smallest at phase 0.49. We also find that the dust shell consists of amorphous carbon and SiC with an inner radius of 2.5 Rstar, and the total optical depths of ?V ? 0.6-0.9 (?11.3 ?m ? 0.003 and 0.004 for amorphous carbon and SiC, respectively) found at phases 0.18 and 0.65 are higher than the value obtained at phase 0.49, ?V ? 0.3 (?11.3 ?m ? 0.001 and 0.002 for amorphous carbon and SiC, respectively). Conclusions: Our MIDI observations and modeling indicate that carbon-rich Miras also have extended layers of polyatomic molecules as previously confirmed in oxygen-rich Miras. The temporal variation of the N-band angular size is largely governed by the variations of the opacity and the geometrical extension of the C2H2 layers and the dust shell, and consequently, this masks the size variation of the photosphere. Also, the observed weakness of the mid-infrared C2H2 absorption in carbon-rich Miras can be explained by the emission from the extended C2H2 layers and the dust shell. Based on observations made with the Very Large Telescope Interferometer of the European Southern Observatory. Program ID: 075.D-0607. Table 4 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/466/1099

Ohnaka, K.; Driebe, T.; Weigelt, G.; Wittkowski, M.

2007-05-01

51

Structural determinants of the outer shell of ?-carboxysomes in Synechococcus elongatus PCC 7942: roles for CcmK2, K3-K4, CcmO, and CcmL.  

PubMed

Cyanobacterial CO(2)-fixation is supported by a CO(2)-concentrating mechanism which improves photosynthesis by saturating the primary carboxylating enzyme, ribulose 1, 5-bisphosphate carboxylase/oxygenase (RuBisCO), with its preferred substrate CO(2). The site of CO(2)-concentration is a protein bound micro-compartment called the carboxysome which contains most, if not all, of the cellular RuBisCO. The shell of ?-type carboxysomes is thought to be composed of two functional layers, with the inner layer involved in RuBisCO scaffolding and bicarbonate dehydration, and the outer layer in selective permeability to dissolved solutes. Here, four genes (ccmK2-4, ccmO), whose products were predicted to function in the outer shell layer of ?-carboxysomes from Synechococcus elongatus PCC 7942, were investigated by analysis of defined genetic mutants. Deletion of the ccmK2 and ccmO genes resulted in severe high-CO(2)-requiring mutants with aberrant carboxysomes, whilst deletion of ccmK3 or ccmK4 resulted in cells with wild-type physiology and normal ultrastructure. However, a tandem deletion of ccmK3-4 resulted in cells with wild-type carboxysome structure, but physiologically deficient at low CO(2) conditions. These results revealed the minimum structural determinants of the outer shell of ?-carboxysomes from this strain: CcmK2, CcmO and CcmL. An accessory set of proteins was required to refine the function of the pre-existing shell: CcmK3 and CcmK4. These data suggested a model for the facet structure of ?-carboxysomes with CcmL forming the vertices, CcmK2 forming the bulk facet, and CcmO, a "zipper protein," interfacing the edges of carboxysome facets. PMID:22928045

Rae, Benjamin D; Long, Benedict M; Badger, Murray R; Price, G Dean

2012-01-01

52

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

53

Anti-inflammatory activity and mechanism of a lipid extract from hard-shelled mussel (Mytilus coruscus) on chronic arthritis in rats.  

PubMed

The present study was designed to investigate the anti-inflammatory activity and mechanism of a lipid extract from hard-shelled mussel (Mytilus coruscus) on adjuvant-induced (AIA) and collagen-induced arthritis (CIA) in rats. AIA and CIA rats that received hard-shelled mussel lipid extract (HMLE group) at a dose of 100 mg/kg demonstrated significantly lower paw swelling and arthritic index, but higher body weight gain than those which received olive oil (control group). Similar results were found in arthritic rats that received New Zealand green-lipped mussel lipid extract (GMLE) at the same dosage. The levels of leukotriene B? (LTB?), prostaglandin E? (PGE?), thromboxane B? (TXB?) in the serum, and interleukin-1? (IL-1?), IL-6, interferon-? (INF-?), tumor necrosis factor-? (TNF-?) in the ankle joint synovial fluids of HMLE group rats were significantly lower than those of control group. However, the levels of IL-4 and IL-10 in HMLE group rats were significantly higher than those in the control group. Decreased mRNA expressions of matrix metalloproteinase 1 (MMP1) and MMP13, but increased tissue inhibitor of metalloproteinase 1 (TIMP1) were observed in the knee joint synovium tissues of HMLE group rats when compared with the control group. No hepatotoxicity was observed in both HMLE and GMLE group rats. The present results indicated that HMLE had a similarly strong anti-inflammatory activity as GMLE. Such a strong efficacy could result from the suppression of inflammatory mediators (LTB?, PGE?, TXB?), pro-inflammatory cytokines (IL-1?, IL-6, INF-?, TNF-?) and MMPs (MMP1, MMP13), and the promotion of anti-inflammatory cytokines (IL-4, IL-10) and TIMPs (TIMP1) productions. PMID:24473164

Li, Guipu; Fu, Yuanqing; Zheng, Jusheng; Li, Duo

2014-02-01

54

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

55

Double-shelled target simulations with LASNEX  

Microsoft Academic Search

Double-shelled inertial confinement fusion targets in which the outer shell is exploded have been studied with LASNEX. To achieve high DT density, configurations have been found in which the inner shell is ablatively driven by the hot outer shell. Calculations indicate that greater than 100 times liquid DT density can be achieved with the Shiva laser while still retaining some

McClellan

1978-01-01

56

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

2013-01-01

57

Organic-inorganic double shell composite microcapsules.  

PubMed

Here we present novel double shell composite microcapsules (melamine formaldehyde (MF) polymer inner shell and ripened CaCO(3) nanoparticle outer shell) prepared using a method based on in situ polymerisation to form a MF polymer shell inside the ripened CaCO(3) nanoparticulate microcapsules wall. PMID:20177627

Long, Yue; Vincent, Brian; York, David; Zhang, Zhibing; Preece, Jon A

2010-03-14

58

Inner shell radial pin geometry and mounting arrangement  

DOEpatents

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

59

Shell-Tile Thermal-Protection System  

NASA Technical Reports Server (NTRS)

Durable shell-tile thermal-protection system consists of interlocking upper and lower hard caps, incorporating appropriate stiffeners and enclosing lightweight fibrous insulation. New shell tile more durable than reusable surface insulation (RSI) currently used on Space Shuttle orbiter.

Macconochie, I. O.; Lowson, A. G.; Kelly, H. N.

1983-01-01

60

Shell forming system  

NASA Technical Reports Server (NTRS)

Hollow shells of high uniformity are formed by emitting liquid through an outer nozzle and gas through an inner nozzle, to form a hollow extrusion, by flowing the gas at a velocity between about 1.3 and 10 times the liquid velocity. The natural breakup rate of the extrusion can be increased to decrease shell size by applying periodic perturbations to one of the materials prior to exiting the nozzles, to a nozzle, or to the extrusion.

Kendall, Jr., James M. (Inventor); Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor)

1990-01-01

61

Thick-shell nanocrystal quantum dots  

DOEpatents

Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.

Hollingsworth, Jennifer A. (Los Alamos, NM); Chen, Yongfen (Eugene, OR); Klimov, Victor I. (Los Alamos, NM); Htoon, Han (Los Alamos, NM); Vela, Javier (Los Alamos, NM)

2011-05-03

62

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

63

Removable inner turbine shell with bucket tip clearance control  

SciTech Connect

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, B.F.; Knuijt, H.M.; Eldrid, S.Q.; Myers, A.; Coneybeer, K.E.; Johnson, D.M.; Kellock, I.R.

2000-07-04

64

Bio-relevant dissolution testing of hard capsules prepared from different shell materials using the dynamic open flow through test apparatus.  

PubMed

Current compendial dissolution and disintegrating testing is unable to mimic physiological conditions affecting gastric drug release from immediate release dosage forms. In order to obtain more realistic data, a novel test setup was developed that we term a 'dynamic open flow through test apparatus'. It is based on the previously described dissolution stress test device and attempts to simulate the intra-gastric dissolution conditions pertinent to immediate release dosage forms administered under fasting conditions with respect to flow rates, intra-gastric temperature profiles and gastric motility. The concept of the dynamic open flow through test apparatus has been tested using five different types of hard capsules: conventional hard gelatin capsules (HGC), three hypromellose based capsules (Vcaps, Vcaps Plus and DRcaps) and pullulan based capsules (Plantcaps). These were of different sizes but all contained 100mg caffeine in each formulation, adjusted to avoid buoyancy by addition of excipient. When the capsules were stressed in the apparatus under the dynamic flow conditions applying mild pressure simulating gastric motility, release from release from Vcaps Plus, Vcaps and Plantcaps capsules was very well comparable to HGC. Capsules are usually swallowed with cold water and the temperature dependency of release from gelatin was noted as a significant factor, since heat exchange in the stomach is slow. PMID:24021609

Garbacz, Grzegorz; Cadé, Dominique; Benameur, Hassan; Weitschies, Werner

2014-06-16

65

Hardness Test  

Microsoft Academic Search

\\u000a The hardness of materials is commonly characterized using indentation techniques. The hardness values depend on the tool employed\\u000a and the measured parameter, for wood, the anisotropy, heterogeneity and hygroscopicity also influence the measurements. In\\u000a this chapter, different methods used for hardness testing of wood are presented. Possible correlations between the different\\u000a hardness figures and other mechanical properties are indicated, in

Mariapaola Riggio; Maurizio Piazza

66

The outer solar system  

Microsoft Academic Search

The outer solar system extends beyond a heliocentric distance of 5 AU. It contains the giant planets and their systems (rings and satellites), the Kuiper belt, the comets (except those which approach episodically the inner solar system) and, at its outer edge, the Oort cloud. The outer solar system physically corresponds to the region located outside the « snow line

T. Encrenaz

2009-01-01

67

Analysis Procedures for Double-Shell Target Concentricity and Wall Thickness  

SciTech Connect

The LLNL Target Fabrication Team (TFT) asked the Center for Non-Destructive Characterization (CNDC) to use CNDC's KCAT or Xradia's Micro computed tomography (CT) system to collect three-dimensional (3D) tomographic data of a set of double-shell targets and determine, among other items, the following: (1) the concentricity of the outer surface of the inner shell with respect to the inner surface of the outer shell with an accuracy of 1-2 micrometers, and (2) the wall thickness uniformity of the outer shell with an accuracy of 1-2 micrometers. The CNDC used Xradia's Micro CT system to collect the data. Bill Brown performed the concentricity analysis, and John Sain performed the wall thickness uniformity analysis. Harry Martz provided theoretical guidance, and Dan Schneberk contributed technical (software) support. This document outlines the analysis procedures used in each case. The double-shell targets, as shown in Figures 1 and 2, consist of an inner shell (or capsule), a two-piece spherical aerogel intermediary shell, and a two-piece spherical outer shell. The three elements are designed and fabricated to be concentric--with the aerogel shell acting as a spacer between the inner shell and outer shell--with no to minimum air gaps in the final assembly. The outer diameters of the aerogel and outer shells are 444 and 550 micrometers, respectively, so the wall thickness of the outer shell is 53 micrometers.

Sain, J D; Brown, W D; Martz, H E; Schneberk, D J

2006-03-02

68

Shell Designs.  

National Technical Information Service (NTIS)

The shell designs consist of two series of related designs (the uniform shell designs and the simplicial shell designs) that are used for fitting second-order response surfaces over spherical regions. The shell designs for two, four, six, and eight factor...

R. B. Crosier

1993-01-01

69

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

Federal Register 2010, 2011, 2012, 2013

...Outer Continental Shelf Sand, Gravel, and Shell Resources for Coastal Restoration and...BOEMRE to obtain OCS sand, gravel, and shell resources for use in shore protection and...procedures for obtaining sand, gravel, and shell resources can be found on the BOEMRE...

2010-09-07

70

Sound Transmission through Two Concentric Cylindrical Sandwich Shells  

NASA Technical Reports Server (NTRS)

This paper solves the problem of sound transmission through a system of two infinite concentric cylindrical sandwich shells. The shells are surrounded by external and internal fluid media and there is fluid (air) in the annular space between them. An oblique plane sound wave is incident upon the surface of the outer shell. A uniform flow is moving with a constant velocity in the external fluid medium. Classical thin shell theory is applied to the inner shell and first-order shear deformation theory is applied to the outer shell. A closed form for transmission loss is derived based on modal analysis. Investigations have been made for the impedance of both shells and the transmission loss through the shells from the exterior into the interior. Results are compared for double sandwich shells and single sandwich shells. This study shows that: (1) the impedance of the inner shell is much smaller than that of the outer shell so that the transmission loss is almost the same in both the annular space and the interior cavity of the shells; (2) the two concentric sandwich shells can produce an appreciable increase of transmission loss over single sandwich shells especially in the high frequency range; and (3) design guidelines may be derived with respect to the noise reduction requirement and the pressure in the annular space at a mid-frequency range.

Tang, Yvette Y.; Silcox, Richard J.; Robinson, Jay H.

1996-01-01

71

Method of fabricating nested shells and resulting product  

DOEpatents

A multiple shell structure and a method of manufacturing such structure wherein a hollow glass microsphere is surface treated in an organosilane solution so as to render the shell outer surface hydrophobic. The surface treated glass shell is then suspended in the oil phase of an oil-aqueous phase dispersion. The oil phase includes an organic film-forming monomer, a polymerization initiator and a blowing agent. A polymeric film forms at each phase boundary of the dispersion and is then expanded in a blowing operation so as to form an outer homogeneously integral monocellular substantially spherical thermoplastic shell encapsulating an inner glass shell of lesser diameter.

Henderson, Timothy M. (Ann Arbor, MI); Kool, Lawrence B. (Ann Arbor, MI)

1982-01-01

72

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

73

Outer planet satellites  

NASA Technical Reports Server (NTRS)

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.

Schenk, Paul M.

1991-01-01

74

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 SiO?/Au/N-doped TiO? 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

2013-08-20

75

Turbine blade with spar and shell  

DOEpatents

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

76

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

77

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

78

Sound Transmission through Cylindrical Shell Structures Excited by Boundary Layer Pressure Fluctuations.  

National Technical Information Service (NTIS)

This paper examines sound transmission into two concentric cylindrical sandwich shells subject to turbulent flow on the exterior surface of the outer shell. The interior of the shells is filled with fluid medium and there is an airgap between the shells i...

J. H. Robinson R. J. Silcox Y. Y. Tang

1996-01-01

79

Interior remodeling of the shell by a gastropod mollusc  

PubMed Central

As the Conus shell grows by spiraling of the outer lip around the axis, profound internal shell dissolution thins the walls of the protected penultimate whorl from several millimeters to <50?m. Shell material is added to the inside of the spire and the anterior part of the columella. The resulting shell has a uniformly thick last whorl and thickened spire that enhance defense against crushing predators and a greatly expanded interior living space for the animal. Images

Kohn, Alan J.; Myers, Elizabeth R.; Meenakshi, V. R.

1979-01-01

80

Multi-element spherical shell generation  

NASA Technical Reports Server (NTRS)

A nozzle assembly in a multi-element spherical shell generation system includes first and second side-by-side spaced apart nozzles and a web portion extending between and connecting the nozzles. The first nozzle has an inner orifice adapted to discharge a first filler material and an outer annular orifice separated from and defined in concentric relation about the inner orifice and adapted to discharge a first shell material. The second nozzle has an inner orifice adapted to discharge a second filler material and an outer annular orifice separated from and defined in concentric relation about the inner orifice and adapted to discharge a second shell material. A multi-element spherical shell can be formed through employment of the nozzle assembly by merger with one another after discharge from the outer orifices of the nozzles of a pair of adjacent annular streams of liquid or molten shell wall material of different compositions and encapsulation by the mixed shell wall materials of a common encapsulated core fluids also simultaneously discharged by the inner orifices nozzles. On the other hand, the pair of encapsulating streams of shell wall material can be of the same materials which merge together and encapsulate core fluids of different compositions which will merge together after discharge from the nozzles.

Morrison, Andrew D. (inventor)

1990-01-01

81

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

82

IRAS Results on Outer Galaxy Star Formation. (Abstract Only).  

National Technical Information Service (NTIS)

An infrared defined (60 micron) sample of IRAS sources were systematically studied in order to investigate star formation in the outer Galaxy. Five percent of the sample are point sources with IRAS spectra that suggest the emission is from a dust shell su...

S. Terebey M. Fich

1989-01-01

83

The Outer Ejecta  

NASA Astrophysics Data System (ADS)

? Carinae is surrounded by a complex circumstellar nebula ejected during more than one eruption, the great eruption in the 1840s and the second or lesser eruption in the 1890s. Beyond the well-defined edges of its famous bipolar nebula are additional nebulous features and ejecta referred to as the outer ejecta. The outer ejecta includes a variety of structures of very different sizes and morphologies distributed in a region 0.67 pc in diameter with a mass of > 2-4 M?. Some individual features in the outer ejecta are moving extremely fast, up to 3,200 km/s, with most of the expansion velocities between 400-900 km/s. As a consequence of these high velocities, structures in the outer ejecta interact with the surrounding medium and with each other. The strong shocks that arise from these interactions give rise to soft X-ray emission. The global expansion pattern of the outer ejecta reveals an overall bipolar distribution, giving a symmetric structure to its morphologically more irregular appearance. The long, highly collimated filaments, called strings, are particularly unusual. The material in the strings follow a Hubble-flow and appear to originate at the central star. The properties of the nebulae associated with other LBVs also are described and compared with ? Car. HR Car and AG Car show similar bipolar morphologies but are much older; HR Car's nebula may be ? Car's older twin. The larger, extended nebulae detected around the giant eruption LBV P Cygni, and the extended nebulosity associated with AG Car and HR Car could be either from previous eruptions or facsimiles to ? Car's outer ejecta.

Weis, Kerstin

84

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

85

Lunch in Outer Space!  

NSDL National Science Digital Library

Students learn about the unique challenges astronauts face while eating in outer space. They explore different food choices and food packaging. Students learn about the engineering design process, and then, as NASA engineering teams, they design and build original model devices to help astronauts eat in a microgravity environment --- their own creative devices for food storage and meal preparation.

Integrated Teaching And Learning Program

86

Outer Planet Icy Satellites  

NASA Technical Reports Server (NTRS)

An outer planet icy satellite is any one of the celestial bodies in orbit around Jupiter, Saturn, Uranus, Neptune, or Pluto. They range from large, planet-like geologically active worlds with significant atmospheres to tiny irregular objects tens of kilometers in diameter. These bodies are all believed to have some type of frozen volatile, existing alone or in combination with other volatiles.

Buratti, B.

1994-01-01

87

Mining outer space  

Microsoft Academic Search

The need to develop new mineral resources as terrestrial supplies are depleted could lead to mining efforts in outer space, where other bodies can be found with materials similar to those of the earth. The high cost of direct sampling requires that earth-based observations be made first, followed by unmanned flights and landing missions. The surface composition of over 100

M. J. Gaffey; T. B. McCord

1977-01-01

88

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

89

Acoustic radiation from single and double ribbed circular cylindrical shells  

NASA Astrophysics Data System (ADS)

Measurements of the acoustic radiation from single and double ribbed circular cylindrical shells were made on the NUSC Transducer Calibration Platform (TCP) in Lake Seneca, NY. Six different types of mechanical drives were used at each of three locations inside the inner shell. Measurements of the shell vibration and acoustic radiation were made with and without outer shells installed around the inner shell structure. For two types of drives, measurements were made with a pressure release layer installed between the inner and outer shell surfaces. Acoustic radiation measurements were made as a function of frequency from 20 to 5,000 Hz and as a function of observation direction at several frequencies for each shell and drive measurement configuration. Measured acoustic radiation data as a function of frequency have been processed. Analysis of the processed data is presented and discussed. It is shown that the location of the drive had a significant effect on the acoustic radiation. The outer shell reduced the acoustic radiation at shell resonant frequencies, but had little effect on other frequencies. The pressure release layer in the double shell had little effect on the acoustic radiation.

Burroughs, C. B.; Hayek, S. I.; Hallander, J. E.; Bostian, D. A.

1984-03-01

90

MORPHOMETRICS OF HARD STRUCTURES IN CUTTLEFISH  

Microsoft Academic Search

Cuttlefishes exhibit several hard structures that have been charac- terised using morphometric analysis. Most of these data come from cuttlebones, al- though statoliths and beaks are also used. It appears that morphometric techniques are mainly used for taxonomic purposes. However, some analyses have emphasised functional morphology and macroevolution. Morphological features (including the inner shell) of cuttlefishes and their availability for

P. NEIGE

2006-01-01

91

Reversible photoswitching of dye-doped core-shell nanoparticles.  

PubMed

We present a simple and versatile mechanism for the reversible photoswitching of dye-doped core-shell nanoparticles. Photochromic dithienylethenes are incorporated into the outer shell, close enough to the dyes entrapped in the core to efficiently quench them by energy transfer when photoconverted with UV light. The emission can be switched back on by irradiation with ? > 450 nm. PMID:21909549

Genovese, Damiano; Montalti, Marco; Prodi, Luca; Rampazzo, Enrico; Zaccheroni, Nelsi; Tosic, Oliver; Altenhöner, Kai; May, Florian; Mattay, Jochen

2011-10-21

92

Nuclear interlevel transfer driven by collective outer shell electron oscillations  

SciTech Connect

The general problem of dynamic electron-nucleus coupling is discussed, and the possibility of using this mechanism to initiate gamma-ray lasing. Single-particle and collective mechanisms are considered. The problems associated with accurate calculation of these processes are discussed, and some numerical results are given. Work in process in described. 10 refs., 7 figs.

Rinker, G.A.; Solem, J.G.; Biedenharn, L.C.

1986-10-20

93

Ionization from the outer shell of Ar by proton impact  

NASA Astrophysics Data System (ADS)

Recent results for proton-argon total ionization cross sections [Kirchner et al. Phys. Rev. Lett. 79, 1658 (1997)] show large disagreement between theory and experiment for energies below 80 keV. To address this problem we have employed a recently developed theoretical method with a more pragmatic approach to the charge screening both in the initial and final channels. The target is considered as a one-electron atom and the interactions between this active electron and remaining target electrons are treated by a model potential including both short- and long-range effects. In the final channel the usual product of two continuum distorted wave functions each associated with a distinct electron-nucleus interaction is used. New results in the present calculation show good agreement in total cross sections for the energy range 10 300 keV with the measurement of Rudd et al. [Rev. Mod. Phys. 57, 965 (1985)].

Bhattacharya, S.; Das, R.; Deb, N. C.; Roy, K.; Crothers, D. S.

2003-11-01

94

Probabilistic Dynamic Buckling of Smart Composite Shells  

NASA Technical Reports Server (NTRS)

A computational simulation method is presented to evaluate the deterministic and nondeterministic dynamic buckling of smart composite shells. The combined use of composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fibers embedded in the plies right below the outer plies. The results show that, on the average, the use of smart fibers improved the shell buckling resistance by about 10 percent at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fiber volume ratio and ply thickness have major effects on the buckling load while uncertainties in the electric field strength and smart material volume fraction have moderate effects. For the specific shell considered in this evaluation, the use of smart composite material is not recommended because the shell buckling resistance can be improved by simply re-arranging the orientation of the outer plies, as shown in the dynamic buckling analysis results presented in this report.

Abumeri, Galib H.; Chamis, Christos C.

2003-01-01

95

Probabilistic Dynamic Buckling of Smart Composite Shells  

NASA Technical Reports Server (NTRS)

A computational simulation method is presented to evaluate the deterministic and nondeterministic dynamic buckling of smart composite shells. The combined use of intraply hybrid composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fibers embedded in the plies right next to the outer plies. The results show that, on the average, the use of smart fibers improved the shell buckling resistance by about 10% at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fiber volume ratio and ply thickness have major effects on the buckling load while uncertainties in the electric field strength and smart material volume fraction have moderate effects. For the specific shell considered in this evaluation, the use of smart composite material is not recommended because the shell buckling resistance can be improved by simply re-arranging the orientation of the outer plies, as shown in the dynamic buckling analysis results presented in this report.

Chamis, Christos C.; Abumeri, Galib H.

2007-01-01

96

Varying the spherical shell geometry in rotating thermal convection  

Microsoft Academic Search

The effect of spherical shell geometry on rapidly-rotating thermal convection is studied in a suite of high resolution three-dimensional numerical simulations. The geometry is characterized by the radius ratio, ? = ri\\/ro, where ri is the inner shell radius, and ro is the outer shell radius. In this study, ? is varied over the broad range 0.10 to 0.92 in

F. M. Al-Shamali; M. H. Heimpel; J. M. Aurnou

2004-01-01

97

Correlation between shell colour and ultrastructure in pheasant eggs.  

PubMed

1. The histochemistry and ultrastructure of pheasant eggs were compared on the basis of blue or brown shell colour. 2. Differences in lectin histochemistry of the outer shell membrane calcification surface indicate a biochemical disruption of the calcification sites in blue eggs. 3. Significant differences were observed in all aspects of eggshell ultrastructure with blue eggs having thinner shells with structural defects. 4. Poor hatchability of blue eggs may reflect high rates of weight loss associated with a defective eggshell. PMID:11469553

Richards, P D; Deeming, D C

2001-07-01

98

K-shell photoionization of multielectron atomic systems  

NASA Technical Reports Server (NTRS)

A simplified procedure is proposed for calculating the cross section for photoionization from the K-shell for a general atomic system that contains an arbitrary number of outer-shell electrons. The procedure retains the formalism of the one-electron atom case (pure Coulomb-field problem) by determining the effective nuclear charge reduced from Z by 'screening parameters' associated with the other K-shell electron and the outer-bound electrons. The parameters are determined essentially by fitting the atom's radial electric field to Coulomb form at the distance from the nucleus where the integrand of the dipole radial integral is peaked.

Gould, R. J.

1980-01-01

99

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

2013-04-01

100

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

101

Study of a double-shell solar house with natural and forced convection  

Microsoft Academic Search

A 2-story double-shell solar house was the subject of the analysis. The house has an inner and outer shell with 30 cm space between. An analysis considering natural convection was used to determine the velocity of the air flow around the space between the shells. Solar gain at the south envelope produces warmed air which rises, while heat loss at

Z. H. Hsu; D. C. Hopkins; C. W. Chiang

1981-01-01

102

Shell Games.  

ERIC Educational Resources Information Center

The author critiques the program design and educational aspects of the Shell Games, a program developed by Apple Computer, Inc., which can be used by the teacher to design objective tests for adaptation to specific assessment needs. (For related articles, see EC 142 959-962.) (Author)

Atkinson, Bill

1982-01-01

103

Vibration of Shells  

NASA Technical Reports Server (NTRS)

The vibrational characteristics and mechanical properties of shell structures are discussed. The subjects presented are: (1) fundamental equations of thin shell theory, (2) characteristics of thin circular cylindrical shells, (3) complicating effects in circular cylindrical shells, (4) noncircular cylindrical shell properties, (5) characteristics of spherical shells, and (6) solution of three-dimensional equations of motion for cylinders.

Leissa, A. W.

1973-01-01

104

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

105

Swelling Kinetics of a Microgel Shell  

NASA Astrophysics Data System (ADS)

Tanaka's approach to swelling kinetics of a solid gel sphere is extended to a spherical microgel shell. The boundary condition at the inner surface is obtained from the minimization of shear elastic energy. Temporal evolution of a shell is represented in a form of expansion over eigenfunctions of the corresponding diffusion equation. The swelling of Tanaka's solid spherical gel is recovered as a special case of our general solution if the inner radius approaches zero. To test our theoretical model, we prepared monodisperse poly-N-isopropylacrylamide (PNIPAM) hydrogel shells using a microfluidic device. The temporal dependence of the inner and outer radii of the shell was measured and the data was fitted to our theoretical model. As a result, we obtained the collective diffusion constants for shrinking and for swelling processes. The obtained values for microgel shells are in excellent agreement with the previous results obtained for sub-millimeter PNIPAM solid spheres in the same temperature interval. Our model shows that the characteristic swelling time of a gel shell should be proportional to the square of its outer radius---just as with Tanaka's model.

Wahrmund, Joshua; Kim, Jin-Woong; Chu, Liang-Yin; Wang, Chanjie; Li, Yong; Fernandez-Nieves, Alberto; Weitz, David A.; Krokhin, Arkadii; Hu, Zhibing

2011-03-01

106

78 FR 1759 - Notice of Approval of Clean Air Act Outer Continental Shelf Minor Source/Title V Minor Permit...  

Federal Register 2010, 2011, 2012, 2013

...Approval of Clean Air Act Outer Continental Shelf Minor Source/Title V Minor Permit Modification Issued to Shell Offshore, Inc...Air Act Outer Continental Shelf (``OCS'') Minor Source/Title V Permit No. R10OCS03000 (``permits''). The...

2013-01-09

107

Outer Solar System Nomenclature  

NASA Technical Reports Server (NTRS)

This grant has supported work by T. Owen and B. A. Smith on planetary and satellite nomenclature, carried out under the general auspices of the International Astronomical Union (IAU). The IAU maintains a Working Group on Planetary and Satellite Nomenclature (WGPSN) whose current chair is Prof.Kaare Aksnes of the Rosseland Institute for Theoretical Astrophysics in Oslo, Norway. Both Owen and Smith are members of the WGPSN; Owen as chair of the Outer Solar System Task Group, and Smith as chair of the Mars Task Group. The major activity during the last grant period (2002) was the approval of several new names for features on Mars by Smith's group and features on Jovian satellites plus new names for satellites of Jupiter, Saturn and Uranus by Owen's group. Much of this work was accomplished by e-mail exchanges, but the new nomenclature was formally discussed and approved at a meeting of the WGPSN held in conjunction with the Division for Planetary Sciences meeting in Birmingham, Alabama in October 2002.

Owen, Tobias C.; Grant, John (Technical Monitor)

2003-01-01

108

The Outer Heliosphere  

NASA Technical Reports Server (NTRS)

In explaining and describing the forces that shape the bubble of solar wind surrounding the Sun, there is a dearth of information. But observations from space are alleviating this situation. Three spacecraft moving away from the Sun-Pioneer 10 and Voyagers 1 and 2-are expected to penetrate the boundaries of the heliosphere within the next few years. All three spacecraft first passed close to Jupiter, and now their extended missions have become explorations of the outer heliosphere. The boundaries of the heliosphere are a standing "termination shock" in the solar wind surrounding the Sun and the "heliopause," dividing the solar wind from the local interstellar medium. Uncertainties about the size and shape of these boundaries make it difficult to estimate exactly the time when the spacecraft will pass them. The termination shock may be nearly spherical or highly elongated, depending on how fast the local interstellar medium is flowing past the heliosphere. Pioneer 10, traveling downstream from the oncoming interstellar wind, may reach the termination shock first if, in fact, the shock is spherical. If the shock is elongated, having a larger dimension in the downstream direction, then Voyagers 1 and 2, traveling upstream, will encounter the shock first. Once these two spacecraft reach the termination shock, they will then pass through a region of solar wind plasma that has been heated by the shock. After a few years, they will pass the heliopause and go into the interstellar medium.

Axford, W. I.; Suess, S. T.

1998-01-01

109

Relativistic electron drift shell splitting  

NASA Astrophysics Data System (ADS)

A survey of equatorial outer radiation belt relativistic electron pitch angle distributions measured on the Polar satellite shows anisotropies that are consistent with the effects of drift shell splitting. Simulations based on the observed radial intensity gradients and on drift shell calculations in a magnetospheric field model show that for low geomagnetic activity levels, the measured average anisotropies are similar to those predicted. With increasing geomagnetic activity the anisotropies do not change as much as is predicted, particularly on the nightside where the pitch angle distributions have local minima in the direction perpendicular to the magnetic field. At a given location and activity level there is substantial variability in the measured anisotropies about their long-term averages.

Selesnick, R. S.; Blake, J. B.

2002-09-01

110

Solutocapillary convection in spherical shells  

NASA Astrophysics Data System (ADS)

A linear stability study of solutocapillary driven Marangoni instabilities in small spherical shells is presented. The shells contain a binary fluid with an evaporating solvent. The viscosity is a strong function of the solvent concentration, the inner surface of the shell is assumed impermeable and stress free, while nonlinear boundary conditions are modeled and prescribed at the receding outer boundary. A time-dependent diffusive state is possible and may lose stability through the Marangoni mechanism due to surface tension dependence on solvent concentration (buoyant forces are negligible in this microscale problem). A frozen-time or quasisteady state linear stability analysis is performed to compute the critical Reynolds number and degree of surface harmonics, as well as the maximum growth rate of perturbations at specified parameters. The development of maximum growth rates in time was also computed by solving the initial value problem with random initial conditions. Results from both approaches are in good agreement except at short times where there is dependence on initial conditions. The physical problem models the manufacturing of spherical shells used as targets in inertial confinement fusion experiments where perfect sphericity is demanded for efficient fusion ignition. It is proposed that the Marangoni instability might be the source of observed surface roughness. Comparisons with the available experiments are made with reasonable qualitative and quantitative agreement.

Subramanian, Pravin; Zebib, Abdelfattah; McQuillan, Barry

2005-01-01

111

The outer detector of Borexino  

NASA Astrophysics Data System (ADS)

The performance of the Borexino Outer Detector is described. It is a large water Cherenkov detector for identifying cosmic muons, penetrating the whole detector system. The Outer Detector is important for tagging cosmic muon generated background events in Borexino. Here, we present the muon identification efficiency and show the capability of muon tracking reconstruction.

Göger-Neff, M.; Lewke, T.; Oberauer, L.; Wurm, M.

2014-05-01

112

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

113

Turbine airfoil with outer wall thickness indicators  

DOEpatents

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

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

2013-08-06

114

Carbon nanotube core graphitic shell hybrid fibers.  

PubMed

A carbon nanotube yarn core graphitic shell hybrid fiber was fabricated via facile heat treatment of epoxy-based negative photoresist (SU-8) on carbon nanotube yarn. The effective encapsulation of carbon nanotube yarn in carbon fiber and a glassy carbon outer shell determines their physical properties. The higher electrical conductivity (than carbon fiber) of the carbon nanotube yarn overcomes the drawbacks of carbon fiber/glassy carbon, and the better properties (than carbon nanotubes) of the carbon fiber/glassy carbon make up for the lower thermal and mechanical properties of the carbon nanotube yarn via synergistic hybridization without any chemical doping and additional processes. PMID:24224730

Hahm, Myung Gwan; Lee, Jae-Hwang; Hart, Amelia H C; Song, Sung Moo; Nam, Jaewook; Jung, Hyun Young; Hashim, Daniel Paul; Li, Bo; Narayanan, Tharangattu N; Park, Chi-Dong; Zhao, Yao; Vajtai, Robert; Kim, Yoong Ahm; Hayashi, Takuya; Ku, Bon-Cheol; Endo, Morinobu; Barrera, Enrique; Jung, Yung Joon; Thomas, Edwin L; Ajayan, Pulickel M

2013-12-23

115

Role of reactant transport in determining the properties of NIF shells made by interfacial polycondensation  

SciTech Connect

Polymer shells up to 2 mm in diameter were prepared using an interfacial polycondensation / cross-linking reaction occurring at the surface of an oil drop. The oil phase is comprised of a solution (20 wt% or less) of isophthaloyl dichloride (IPC) dissolved in an organic solvent. An interfacial reaction is initiated when the IPC-loaded oil drop is submerged in an aqueous solution of poly(p-vinylphenol) (PVP), a poly(electrolyte) at elevated pH. Composition, structure, and surface finish for fully-formed dry shells were assessed using a number of techniques including scanning electron microscopy (SEM), atomic force microscopy (AFM), fourier-transform infrared spectroscopy (FTIR), pyrolysis-gas chromatography (GC) mass spectroscopy (MS), microhardness measurements, gas permeability, and solvent permeability measurements. From deposition rate data, a reaction mechanism and key reaction parameters were identified. The deposition rate of shell membrane material was found to be a diffusion limited reaction of IPC through the forming membrane to the exterior shell interface (which is believed to be the reaction front). The final thickness of the film deposited at the interface and the rate of deposition were found to be strong functions of the IPC concentration and oil phase solvent. Films made with diethyl phthalate (DEP) were thinner and harder than films made using 1,6-dichlorohexane (DCH) as a solvent. Differences in solubility of the forming membrane in DCH and DEP appear to be able to account for the differences in deposition rate and the hardness (related to cross-linking density). The deposition can be thought of as a phase separation which is affected by both the poly(electrolyte) / ionomer transition and the amount of cross-linking. Finally, it was found that the choice of oil phase solvent profoundly affects the evolution of the outer surface roughness.

Hamilton, K.E.; Letts, S.A.; Buckley, S.R.; Fearon, E.M.; Wilemski, G.; Cook, R.C. [Lawrence Livermore National Lab., CA (United States); Schroen-Carey, D. [W.J. Schafer and Associates, Livermore, CA (United States)

1997-03-01

116

Comparative analysis of shell rendering and shear-warp rendering  

NASA Astrophysics Data System (ADS)

In Medical Imaging, shell rendering and shear-warp rendering are two of the most efficient and effective voxel-based techniques for volume visualization. This work presents a comparative analysis of shell rendering and shear-warp rendering in terms of storage, speed, and image quality. We have chosen 10 different objects of various sizes, shapes and topologies and one 1-GHz Pentium-III PC with 512 MB RAM for our experiments. Hard and fuzzy boundaries of up to 2,833 K voxels in size have been created to test both methods in surface and volume rendering, respectively. Hard surface shell rendering and surface shear-warp rendering required less than 0.5 second. In the worst case, volume shell rendering required 1.45 second, while volume shear-warp rendering spent 0.65 second for the same task. Shear-warp rendering uses on average from 3 to 6 times more memory space than shell rendering, but it can be up to 2.79 times faster than shell rendering. On average, shear-warp rendering is as fast as shell rendering for hard boundaries and 1.7 times faster than shell rendering for fuzzy boundaries. We have also observed that both can produce similar high-quality images.

Falcao, Alexandre X.; Rocha, Leonardo M.; Udupa, Jayaram K.

2002-05-01

117

Hard Rock Penetration Technology.  

National Technical Information Service (NTIS)

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 Overvi...

2005-01-01

118

Thermoelectric Outer Planets Spacecraft (TOPS)  

NASA Technical Reports Server (NTRS)

The research and advanced development work is reported on a ballistic-mode, outer planet spacecraft using radioisotope thermoelectric generator (RTG) power. The Thermoelectric Outer Planet Spacecraft (TOPS) project was established to provide the advanced systems technology that would allow the realistic estimates of performance, cost, reliability, and scheduling that are required for an actual flight mission. A system design of the complete RTG-powered outer planet spacecraft was made; major technical innovations of certain hardware elements were designed, developed, and tested; and reliability and quality assurance concepts were developed for long-life requirements. At the conclusion of its active phase, the TOPS Project reached its principal objectives: a development and experience base was established for project definition, and for estimating cost, performance, and reliability; an understanding of system and subsystem capabilities for successful outer planets missions was achieved. The system design answered long-life requirements with massive redundancy, controlled by on-board analysis of spacecraft performance data.

1973-01-01

119

Strategy for Outer Planets Exploration.  

National Technical Information Service (NTIS)

NASA's Planetary Programs Office formed a number of scientific working groups to study in depth the potential scientific return from the various candidate missions to the outer solar system. The results of these working group studies were brought together...

1975-01-01

120

The Double Chooz Outer Veto  

NASA Astrophysics Data System (ADS)

Double Chooz is unique among reactor neutrino experiments for its Outer Veto -- a multi-layered plastic scintillator strip muon detector. The far detector Outer Veto covers 95,^2 on top of the main detector volumes and is composed of 44 modules, each made up of 64 scintillator strips outfitted with wavelength-shifting fibers coupled to a multi-anode PMT. The Outer Veto serves two purposes: first, as a veto, it reduces muon-induced backgrounds to the neutrino signal, in particular the fast neutron and stopping muon backgrounds; second, the high-quality muon tracking it provides allows for detailed studies of these backgrounds, as well as long-lived backgrounds, which cannot be vetoed, such as ^9Li and ^8He. I will describe the design of the Outer Veto, its performance, and some background studies.

Conover, Emily

2013-04-01

121

Wear of hard materials by hard particles  

SciTech Connect

Hard materials, such as WC-Co, boron carbide, titanium diboride and composite carbide made up of Mo2C and WC, have been tested in abrasion and erosion conditions. These hard materials showed negligible wear in abrasion against SiC particles and erosion using Al2O3 particles. The WC-Co materials have the highest wear rate of these hard materials and a very different material removal mechanism. Wear mechanisms for these materials were different for each material with the overall wear rate controlled by binder composition and content and material grain size.

Hawk, Jeffrey A.

2003-10-01

122

Hardness of Covalent Crystals  

Microsoft Academic Search

Based on the idea that the hardness of covalent crystal is intrinsic and equivalent to the sum of the resistance to the indenter of each bond per unit area, a semiempirical method for the evaluation of hardness of multicomponent crystals is presented. Applied to beta-BC2N crystal, the predicted value of hardness is in good agreement with the experimental value. It

Faming Gao; Julong He; Erdong Wu; Shimin Liu; Dongli Yu; Dongchun Li; Siyuan Zhang; Yongjun Tian

2003-01-01

123

Orbital momentum profiles and binding energy spectra for the complete valence shell of molecular fluorine.  

National Technical Information Service (NTIS)

The first electronic structural study of the complete valence shell binding energy spectrum of molecular fluorine, encompassing both the outer and inner valence regions, is reported. These binding energy spectra as well as the individual orbital momentum ...

Y. Zheng C. E. Brion M. J. Brunger K. Zhao A. M. Grisogono

1996-01-01

124

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

125

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

126

Shell-armored wood cobbles as a potential criterion for detrital coal deposits  

SciTech Connect

Shell-armored wood cobbles occur on detrital-peat beaches along the seaward edge of the Mississippi Delta. Shell material consists exclusively of Mulinia lateralis, a dwarf surf clam. Soft, heavy, waterlogged wood fragments are abraded and become armored by hard shells in response to wave activity on the beach. Although their preservation potential is suspect, fossilized shell-armored wood clasts would probably be recognized as a type of coal ball and might indicate an allochthonous origin for the host coal.

DiMarco, M.J.; Nummedal, D.

1986-01-01

127

Handbook of hard coatings  

SciTech Connect

This book discusses the hard coatings classified as tribologically hard, which are wear resistant and low friction. Three sections discuss tribological properties and new developments. With the development of modern technology in the areas of optical, optoelectronic, and defense related applications, the traditional term hard coatings can be extended. Thus, a system which operates satisfactorily, in a given environment can be said to be hard with respect to that environment. Many hard coatings are ceramic compounds such as oxides, carbides, nitrides, ceramic alloys, cements, diamonds and cubic nitride.

Bunshah, R.; Weissmantel, C. [eds.

2000-07-01

128

Single and dual-band multimode hard horn antennas with partly corrugated walls  

Microsoft Academic Search

We introduce a partly corrugated hard horn, consisting of a smooth-walled horn with an attached longitudinally corrugated outer section. This alleviates the problems with the manufacturing when the longitudinal corrugations extend into the throat of the horn. The transition between the inner smooth walled part and the outer corrugated part is abrupt. This is used and controlled to design better

Omid Sotoudeh; Per-Simon Kildal; Per Ingvarson; Sergei P. Skobelev

2006-01-01

129

A pulsatile drug delivery system based on rupturable coated hard gelatin capsules  

Microsoft Academic Search

The objective of this study was to develop and evaluate a pulsatile drug delivery system based on drug-containing hard gelatin capsules, which were coated with a swelling layer and an outer insoluble, water-permeable polymeric coating. An inner pressure developed by the swelling layer resulted in the rupture of the outer coating. Preliminary studies with a simulated rupture test demonstrated the

T. Bussemer; A. Dashevsky; R. Bodmeier

2003-01-01

130

Formation of shells in major mergers  

NASA Technical Reports Server (NTRS)

Numerical simulations are used to study the fate of disks in mergers between equal-mass galaxies. Contrary to popular belief, mergers between equal-mass galaxies can form shells, loops, and ripples. Material that was originally in the outer disk of the premerger spirals falls into the remnant late in the merger event, long after the inner region of the remnant has relaxed. Thus, its evolution is similar to that of an accreted dwarf satellite that forms shells through 'phase wrapping'. However, the mechanism described in this letter avoids a number of difficulties with the accretion model; specifically, it can explain the observed correlation between properties of the host galaxies and shell alignments and luminosities. In view of this, we argue that many shell systems may have originated through 'major' mergers of comparable-mass galaxies rather than via 'minor' mergers or accretions. In particular, the shell elliptical NGC 3923 appears to be a good candidate for shell formation by a major merger.

Hernquist, Lars; Spergel, David N.

1992-01-01

131

Does the Crab Have a Shell?  

NASA Astrophysics Data System (ADS)

We present deep images of a region around the Crab Nebula made with the VLA, utilizing new imaging and deconvolution algorithms in a search for a faint radio shell. The existence of a high-velocity, hydrogen-rich envelope has been predicted to account for the low total mass and kinetic energy of the observed nebula. No radio emission was detected from an extended source outside the Crab Nebula. Our limits on surface brightness are sufficiently low to rule out the existence of a shell around the Crab whose brightness is at least 2 orders of magnitude below that of SN 1006, the faintest historical shell-type supernova remnant. We consider models for the progenitor star and the presupernova environment and conclude that if a fast, outer shock exists, then it has a sharply reduced efficiency at accelerating relativistic particles from the kinetic energy of the blast wave. We also looked for a steepening of the spectral index along the boundary of the Crab Nebula itself, the signature of an outer shock. However, contrary to previous claims, no such steepening was found. The absence of any evidence at radio wavelengths that either the Crab Nebula or a hypothetical shell is interacting with the ambient medium leads to an interpretation that the supernova of A.D. 1054 was a peculiar low-energy event.

Frail, D. A.; Kassim, N. E.; Cornwell, T. J.; Goss, W. M.

1995-12-01

132

Frequency Response Model and Simulation of Transmembrane Potentials on Cellular Inner and Outer Membranes  

Microsoft Academic Search

In order to calculate transmembrane potentials of both inner and outer membranes more accurately, this paper presented a multi-shelled dielectric model for spherical cell according to the structure of cell, because the influence of organelles such as nuclear on the electric field distribution should be account for. Based on this model, the general method for analyzing the frequency response of

Xin Chen; Chenguo Yao; Chengxiang Li; Caixin Sun; Yan Mi; Cong Li; Lina Hu

2007-01-01

133

Origin of Outer Solar System  

NASA Technical Reports Server (NTRS)

Our ongoing research program combines extensive deep and wide-field observations using a variety of observational platforms with numerical studies of the dynamics of small bodies in the outer solar system in order to advance the main scientific goals of the community studying the Kuiper belt and the outer solar system. These include: (1) determining the relative populations of the known classes of KBOs as well as other possible classes; ( 2 ) determining the size distributions or luminosity function of the individual populations or the Kuiper belt as a whole; (3) determining the inclinations distributions of these populations; (4) establishing the radial extent of the Kuiper belt; ( 5 ) measuring and relating the physical properties of different types of KBOs to those of other solar system bodies; and, (6) completing our systematic inventory of the satellites of the outer planets.

Holman, Matthew J.; Lindstrom, David (Technical Monitor)

2005-01-01

134

Vibration effect on hardness measurement  

Microsoft Academic Search

In this paper, the effect of ground vibration on hardness measurement, Rockwell scale C hardness, Vickers scale HV1 hardness and Leeb hardness is studied. The hardness machines were placed on the vibration table. The vibration signal is single frequency sinusoidal wave, which frequency and amplitude of vibration can be controlled. The hardness value at free from vibration state is used

Tassanai Sanponpute; Apichaya Meesaplak

2010-01-01

135

Hardness of Quasicrystals  

NASA Astrophysics Data System (ADS)

Vickers hardness measurements have been made at room temperature for four thermodynamically stable quasicrystals. The hardness value of Al-Li-Cu icosahedral quasicrystal is about 500 (kg/mm2) and those of Al-transition metal quasicrystals are commonly around 1000, which is extremely high for aluminum based alloys. Anisotropy in the hardness in Al-Co-Ni decagonal quasicrystal is rather small.

Takeuchi, Shin; Iwanaga, Hiroshi; Shibuya, Tadaharu

1991-03-01

136

Stability of axially compressed cylindrical composite shells in the presence of nonstationary heating  

Microsoft Academic Search

The problem of smooth cylindrical composite shells uniformly compressed in the axial direction and subjected to nonstationary heating is solved in the linear quasi-static formulation. Expressions are obtained for the critical loads and their regions of application are determined. The calculations are compared with experimental data obtained by linearly heating the outer surface of axially compressed smooth cylindrical shells of

L. G. Belozerov; V. A. Kireev

1973-01-01

137

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

138

Genotype-specific growth of hard clams (genus Mercenaria ) in a hybrid zone: variation among habitats  

Microsoft Academic Search

Shell growth rate is an important component of fitness in bivalve molluscs. Using the ? parameter computed from the von Bertalanffy growth equation, we quantitatively compared rates of annual shell grwoth among the hard clams Mercenaria mercenaria, M. campechiensis, and their hybrids sampled from a variety of habitats in the Indian River lagoon, Florida, USA, a zone of species overlap

W. S. Arnold; T. M. Bert; D. C. Marelli; H. Cruz-Lopez; P. A. Gill

1996-01-01

139

IRAS results on outer galaxy star formation  

NASA Technical Reports Server (NTRS)

An infrared defined (60 micron) sample of IRAS sources were systematically studied in order to investigate star formation in the outer Galaxy. Five percent of the sample are point sources with IRAS spectra that suggest the emission is from a dust shell surrounding a mature star. Ninety five percent have spectra where flux density strictly rises with wavelength. The sources are extended, and it is shown that Point Source Catalog fluxes seriously underestimate total fluxes. CO kinematic distances were reliably assigned to two thirds of the sources. Most of the infrared luminosities correspond to B spectral types. Six cm continuum emission were detected from all sources inferred to have spectral type B1 or earlier. The combined IRAS/CO/6 cm data show these sources are young, moderately massive stars that are embedded in interstellar clouds. The young embedded sources define a distinct band in an IRAS color-colar diagram. Normal IRAS galaxies fall in the same band, consistent with the interpretation that their infrared emission is due to star formation.

Terebey, Susan; Fich, Michel

1989-01-01

140

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...

141

The Law of Outer Space  

Microsoft Academic Search

The Soviet author somewhat repetitiously discusses the concepts of air space and national sovereignty in the space age. He summarizes the opinions of a number of Western authorities on international law and notes that most of them agree with the Soviet view that state sovereignty does not extend to outer space. Certain official Soviet views and proposals concerning airspace violations,

A. Galina

1959-01-01

142

Formation of the outer planets  

Microsoft Academic Search

A discussion is given of a number of physical processes which were probably important during the formation of the outer planets if these formed from a gaseous solar nebula in which magnetic effects were not important. Arguments are given that large-scale gravitational instabilities in the solar nebula did not occur. Qualitative consideration is given to the conditions in which dynamical

A. G. W. Cameron

1973-01-01

143

Slingshot to the Outer Planets  

NSDL National Science Digital Library

Students are introduced to the engineering challenges involved with interplanetary space travel. In particular, they learn about the gravity assist or "slingshot" maneuver often used by engineers to send spacecraft to the outer planets. Using magnets and ball bearings to simulate a planetary flyby, students investigate what factors influence the deflection angle of a gravity assist maneuver.

Integrated Teaching And Learning Program

144

The pollen tube: a soft shell with a hard core.  

PubMed

Plant cell expansion is controlled by a fine-tuned balance between intracellular turgor pressure, cell wall loosening and cell wall biosynthesis. To understand these processes, it is important to gain in-depth knowledge of cell wall mechanics. Pollen tubes are tip-growing cells that provide an ideal system to study mechanical properties at the single cell level. With the available approaches it was not easy to measure important mechanical parameters of pollen tubes, such as the elasticity of the cell wall. We used a cellular force microscope (CFM) to measure the apparent stiffness of lily pollen tubes. In combination with a mechanical model based on the finite element method (FEM), this allowed us to calculate turgor pressure and cell wall elasticity, which we found to be around 0.3 MPa and 20-90 MPa, respectively. Furthermore, and in contrast to previous reports, we showed that the difference in stiffness between the pollen tube tip and the shank can be explained solely by the geometry of the pollen tube. CFM, in combination with an FEM-based model, provides a powerful method to evaluate important mechanical parameters of single, growing cells. Our findings indicate that the cell wall of growing pollen tubes has mechanical properties similar to rubber. This suggests that a fully turgid pollen tube is a relatively stiff, yet flexible cell that can react very quickly to obstacles or attractants by adjusting the direction of growth on its way through the female transmitting tissue. PMID:23106269

Vogler, Hannes; Draeger, Christian; Weber, Alain; Felekis, Dimitris; Eichenberger, Christof; Routier-Kierzkowska, Anne-Lise; Boisson-Dernier, Aurélien; Ringli, Christoph; Nelson, Bradley J; Smith, Richard S; Grossniklaus, Ueli

2013-02-01

145

Circumstellar shells resolved in IRAS survey data. II - Analysis  

NASA Technical Reports Server (NTRS)

IRAS survey data for 512 red giant stars and young planetary nebulae were processed using a computer program which fitted the data to an idealized model of a circumstellar shell. Seventy-six of these stars were found to have circumstellar shells resolved in the 60-micron survey data. Forty pct of the 76 stars are carbon stars. Thirteen are Mira variables. The evolution of these shells, involving the interaction of the expelled material with the ISM, is modeled, and the results suggest that the period during which Mira variables lose mass lasts for approximately 10 exp 5 yr. Carbon stars are found to shed mass for about 2 x 10 exp 5 yr. The expansion velocity of the outer shell for the largest shells will normally be lower by a factor of 3-5 than the expansion velocity obtained from CO observations.

Young, K.; Phillips, T. G.; Knapp, G. R.

1993-01-01

146

Strategy for exploration of the outer planets: 1986-1996  

NASA Technical Reports Server (NTRS)

Over the past decade COMPLEX has published three strategy reports which, taken together, encompass the entire planetary system and recommend a coherent program of planetary exploration. The highest priority for outer planet exploration during the next decade is intensive study of Saturn (the planet, satellites, rings, and magnetosphere) as a system. The Committee additionally recommends that NASA engage in the following supporting activities: increased support of laboratory and theoretical studies; pursuit of earth-based and earth-orbital observations; commitment to continued operation of productive spacecraft; implementation of the instrument development plan as appropriate for the outer solar system; studies of deep atmospheric probes; development of penetrators or other hard landers; development of radiation-hardened spacecraft; and development of low-thrust propulsion systems. Longer-term objectives include exploration and intensive study of: the Uranus and Neptune systems; planetology of the Galilean satellites and Titan; and the inner Jovian system.

1986-01-01

147

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

148

The effect of size on the acoustic response of polymer-shelled ultrasound microbubble contrast agents  

NASA Astrophysics Data System (ADS)

Hard-shelled microbubble contrast agents differ from lipid-shelled agents in that the extra stability provided by their shell prevents dissolution of small gas bubbles: consequently, stable agents can be manufactured with diameters below 1 ?m. Near-micron and submicron-sized contrast agents may enable new biomedical applications because they can traverse narrow barriers such as the lymphatic endothelium and the permeable vascular endothelium found in actively growing solid tumors. However, several studies have suggested fundamental differences in the mechanisms of acoustic response of ``soft'' lipid-shelled ultrasound microbubble contrast agents and ``hard'' albumin- or polymer-shelled agents. In particular, hard-shelled contrast agents exhibit strong echoes only after the shell is damaged and the enclosed gas is allowed to oscillate freely. Here three polymer-shelled agents with mean diameters of 0.74 ?m, 0.91 ?m, and 1.33 ?m (POINT Biomedical Corp.) are investigated. Significant differences among the agents exist in the probability of response to acoustic interrogation, but not the amplitude or frequency of their acoustic response. These results are explained by a hypothesis of a pressure-dependent threshold diameter above which single hard-shelled agents respond to acoustic interrogation. The implications of this hypothesis for the design of imaging methods and clinical protocols using these agents will be presented.

Bloch, Susannah H.; Ferrara, Katherine W.; Wisner, Erik R.

2005-04-01

149

Monodisperse magnetic core/shell microspheres with Pd nanoparticles-incorporated-carbon shells.  

PubMed

This work reports a hard self-template method to synthesize core/shell like Fe3O4@C microparticles, in which the Pd nanocrystals can be alternatively incorporated into the carbon shells. The Fe3O4@polyaniline core/shell microspheres were first synthesized as the precursor by in situ polymerization of aniline onto the surface of the Fe3O4 microspheres. In a subsequent carbonization of the precursor under a vacuum oven, the Fe3O4 core was preserved and the polyaniline shell transferred into carbon shells enveloping the magnetic sphere, forming magnetic Fe3O4@C microspheres. The Pd ions could be impregnated into the polyaniline shell, and thus the obtained composites were transformed into Fe3O4@C/Pd microspheres under the same vacuum heating progress. The as-obtained system demonstrates superparamagnetic characteristics, which would benefit its potential application in nanocatalysts. This strategy provides an efficient approach for tailoring core/shell materials with desired functionalities and structures by adjusting the precursors and structure-directing agents. PMID:24323164

Fang, Qunling; Cheng, Qing; Xu, Huajian; Xuan, Shouhu

2014-02-14

150

The hard metal diseases  

SciTech Connect

Hard metal is a mixture of tungsten carbide and cobalt, to which small amounts of other metals may be added. It is widely used for industrial purposes whenever extreme hardness and high temperature resistance are needed, such as for cutting tools, oil well drilling bits, and jet engine exhaust ports. Cobalt is the component of hard metal that can be a health hazard. Respiratory diseases occur in workers exposed to cobalt--either in the production of hard metal, from machining hard metal parts, or from other sources. Adverse pulmonary reactions include asthma, hypersensitivity pneumonitis, and interstitial fibrosis. A peculiar, almost unique form of lung fibrosis, giant cell interstitial pneumonia, is closely linked with cobalt exposure.66 references.

Cugell, D.W. (Department of Medicine, Northwestern University Medical School, Chicago, IL (United States))

1992-06-01

151

Turbine airfoil with a compliant outer wall  

DOEpatents

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

152

Hollow Pollen Shells to Enhance Drug Delivery  

PubMed Central

Pollen grain and spore shells are natural microcapsules designed to protect the genetic material of the plant from external damage. The shell is made up of two layers, the inner layer (intine), made largely of cellulose, and the outer layer (exine), composed mainly of sporopollenin. The relative proportion of each varies according to the plant species. The structure of sporopollenin has not been fully characterised but different studies suggest the presence of conjugated phenols, which provide antioxidant properties to the microcapsule and UV (ultraviolet) protection to the material inside it. These microcapsule shells have many advantageous properties, such as homogeneity in size, resilience to both alkalis and acids, and the ability to withstand temperatures up to 250 °C. These hollow microcapsules have the ability to encapsulate and release actives in a controlled manner. Their mucoadhesion to intestinal tissues may contribute to the extended contact of the sporopollenin with the intestinal mucosa leading to an increased efficiency of delivery of nutraceuticals and drugs. The hollow microcapsules can be filled with a solution of the active or active in a liquid form by simply mixing both together, and in some cases operating a vacuum. The active payload can be released in the human body depending on pressure on the microcapsule, solubility and/or pH factors. Active release can be controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell.

Diego-Taboada, Alberto; Beckett, Stephen T.; Atkin, Stephen L.; Mackenzie, Grahame

2014-01-01

153

Hollow pollen shells to enhance drug delivery.  

PubMed

Pollen grain and spore shells are natural microcapsules designed to protect the genetic material of the plant from external damage. The shell is made up of two layers, the inner layer (intine), made largely of cellulose, and the outer layer (exine), composed mainly of sporopollenin. The relative proportion of each varies according to the plant species. The structure of sporopollenin has not been fully characterised but different studies suggest the presence of conjugated phenols, which provide antioxidant properties to the microcapsule and UV (ultraviolet) protection to the material inside it. These microcapsule shells have many advantageous properties, such as homogeneity in size, resilience to both alkalis and acids, and the ability to withstand temperatures up to 250 °C. These hollow microcapsules have the ability to encapsulate and release actives in a controlled manner. Their mucoadhesion to intestinal tissues may contribute to the extended contact of the sporopollenin with the intestinal mucosa leading to an increased efficiency of delivery of nutraceuticals and drugs. The hollow microcapsules can be filled with a solution of the active or active in a liquid form by simply mixing both together, and in some cases operating a vacuum. The active payload can be released in the human body depending on pressure on the microcapsule, solubility and/or pH factors. Active release can be controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell. PMID:24638098

Diego-Taboada, Alberto; Beckett, Stephen T; Atkin, Stephen L; Mackenzie, Grahame

2014-01-01

154

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

2011-06-01

155

Formation of Gaseous Shells  

NASA Astrophysics Data System (ADS)

HI observations have revealed in several shell galaxies the presence of gaseous shells slightly displaced from the stellar shells radially, in the outward direction. We propose a mechanism to form this gaseous shells, based on the well-known phase-wrapping process of the companion matter in a merger, with nearly radial orbits. The mechanism relies on the existence of a clumpy interstellar matter, and on dynamical friction experienced by the companion core.

Combes, F.; Charmandaris, V.

156

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

157

Geometrical interpretation for the outer SU(3) outer multiplicity label  

NASA Technical Reports Server (NTRS)

A geometrical interpretation for the outer multiplicity rho that occurs in a reduction of the product of two SU(3) representations, (lambda(sub pi), mu(sub pi)) x (lambda(sub nu), mu(sub nu)) approaches sigma(sub rho)(lambda, mu)(sub rho), is introduced. This coupling of proton (pi) and neutron (nu) representations arises, for example, in both boson and fermion descriptions of heavy deformed nuclei. Attributing a geometry to the coupling raises the possibility of introducing a simple interaction that provides a physically meaningful way for distinguishing multiple occurrences of (lambda, mu) values that can arise in such products.

Draayer, Jerry P.; Troltenier, D.

1995-01-01

158

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

159

Manipulation of emission energy in GaAs/AlGaAs core-shell nanowires with radial heterostructure  

NASA Astrophysics Data System (ADS)

Photoluminescence was studied in GaAs/AlGaAs nanowires (NWs) with different radial heterostructures. We demonstrated that manipulation of the emission energy may be achieved by appropriate choice of the shell structure. The emission at highest energy is generated in the NWs with tunneling thin AlGaAs inner shell and thin GaAs outer shell due to recombination of the photoexcited electrons confined in the outer shell with the holes in the core. Lower energy emission was shown to occur in the NWs with thick outer shell grown in the form of a short-period GaAs/AlGaAs multiple quantum well structure. In this case, the tunneling probability through the multiple quantum wells controls the energy emitted by the NWs. The doping of core results in dominated low energy emission from the GaAs core.

Barbosa, B. G.; Arakaki, H.; de Souza, C. A.; Pusep, Yu. A.

2014-03-01

160

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

161

Micro\\/nanomechanical characterization of a natural nanocomposite material---the shell of Pectinidae  

Microsoft Academic Search

Micro\\/nanomechanical characterization of the shell of a scallop, a member of the Pectinidae family, has been carried out. Hardness and elastic modulus were measured by nanoindentation using a nanoindenter. Micro\\/nanoscale cracks were generated by microindentation using a microindenter. The shell's crossed lamellar structure and indentation cracks were imaged using an optical microscope, an atomic force microscope and a scanning electron

Xiaodong Li; Patrick Nardi

2004-01-01

162

Instrumental Texture Profile Analysis (TPA) of Shelled Sunflower Seed Caramel Snack Using Response Surface Methodology  

Microsoft Academic Search

Models capable of predicting product quality of shelled sunflower seed caramel snack have been developed using response surface methodology. The textural profile analysis was conducted on the snacks using a texture analyzer. The quality attributes measured were hardness, cohesiveness, springiness, chewiness, and resilience as a function of sugar and sunflower kernels content. The sugar and shelled seed proportions affect the

R. K. Gupta; Alka Sharma; R. Sharma

2007-01-01

163

Fluctuating shells under pressure.  

PubMed

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. PMID:23150558

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

2012-11-27

164

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

165

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.

166

The foreshocks of outer planets  

NASA Astrophysics Data System (ADS)

The presence of non-absorbing planetary obstacles in the supermagnetosonic solar wind makes foreshocks a rather common element throughout the solar system. Although the observations at Earth represent a vital element in the study of the physical processes occurring on planetary foreshocks at large, these phenomena necessarily occur at the particular parameter values relevant for our planet. In particular, the shocks of the outer planets are characterized by high solar wind Mach numbers, and in the case of the giant planets, by an extremely high size parameter/solar wind ion gyroradius ratio, in contrast to small magnetized planets, or unmagnetized planets such as Mercury and Mars, respectively. In addition, the geometry of their foreshocks present symmetries associated with the evolution of the interplanetary magnetic field direction with heliospheric distance, and waves within a range of frequencies which is unusual for the inner solar system. In this work, we review past and current studies on the foreshocks of outer planets from in situ magnetic field and plasma observations, with emphasis on Jupiter and Saturn. In particular, we will discuss the properties of plasma waves found within their ion foreshocks, the possible mechanisms generating them, and the similarities and differences with foreshock wave phenomena at Earth.

Bertucci, C.; Andres, N.; Gomez, D. O.; Mazelle, C. X.; Achilleos, N. A.; Dougherty, M. K.

2012-12-01

167

Manganese speciation in Diplodon chilensis patagonicus shells: a XANES study  

Microsoft Academic Search

In addition to other types of climate archives, biogenic skeletons of a variety of different organisms (i.e. shells of bivalves, skeletal hard parts of corals or sponges) are increasingly used for high-resolution climate reconstructions. Bivalves are particularly suited for such analyses because they are geographically broadly distributed and have been shown to record climate and environmental information reliably and over

A. L. Soldati; V. Vicente-Vilas; J. Goettlicher; D. E. Jacob

2009-01-01

168

Synthesis of the double-shell anatase-rutile TiO2 hollow spheres with enhanced photocatalytic activity  

NASA Astrophysics Data System (ADS)

A novel double-shell TiO2 hollow sphere with an inner anatase shell and an outer rutile shell was synthesized by a simple sol-gel method and silica protected calcination process. The structure and formation mechanism was proposed based on characterization using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The double-shell spheres have a uniform diameter of 360 nm and a typical yolk-shell structure. Moreover, the double-shell TiO2 hollow spheres possess a large specific surface area (169 m2 g-1). Due to the high surface area, multiple light reflection and beneficial electron conduction between the inner anatase and outer rutile shell of this special structure, the as-prepared double-shell TiO2 catalysts show remarkably enhanced photoactivity compared to the commercial P25 catalyst. In particular, rhodamine B molecules can be completely decomposed in the presence of the double-shell spheres after 60 minutes of irradiation with UV light. In addition, the high activity is retained after five cycles, indicating the stability and reusability of the double-shell catalyst.A novel double-shell TiO2 hollow sphere with an inner anatase shell and an outer rutile shell was synthesized by a simple sol-gel method and silica protected calcination process. The structure and formation mechanism was proposed based on characterization using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The double-shell spheres have a uniform diameter of 360 nm and a typical yolk-shell structure. Moreover, the double-shell TiO2 hollow spheres possess a large specific surface area (169 m2 g-1). Due to the high surface area, multiple light reflection and beneficial electron conduction between the inner anatase and outer rutile shell of this special structure, the as-prepared double-shell TiO2 catalysts show remarkably enhanced photoactivity compared to the commercial P25 catalyst. In particular, rhodamine B molecules can be completely decomposed in the presence of the double-shell spheres after 60 minutes of irradiation with UV light. In addition, the high activity is retained after five cycles, indicating the stability and reusability of the double-shell catalyst. Electronic supplementary information (ESI) available: UV-vis diffuse reflection spectra and the summarisation of BET surface and average pore size. See DOI: 10.1039/c3nr04043g

Li, Shunxing; Chen, Jie; Zheng, Fengying; Li, Yancai; Huang, Fuying

2013-11-01

169

Double-shell capsules, an alternative to the single-shell cryogenic NIF design  

NASA Astrophysics Data System (ADS)

Recently, Los Alamos has renewed its effort[1] to design and evaluate double-shell capsules as an alternative to the single- shell cryogenic NIF design.[2] The recent work by Livermore is being used as a starting point.[3-4] One to two megajoules of laser energy is used as input into the designs being considered. Sensitivity studies to P2 and P4 radiation flux asymmetries have been done and are presented in a separate talk.[5] Also, mix calculations of both the NIF capsule design and the double-shell design recently fielded on Omega3 will be presented in another talk.[6] Fully integrated calculations of the double-shell designs will be presented. Preliminary simulations with Rage, an Eulerian AMR code, will be shown that address the issue associated with gaps created by bringing two hemispheres together to create the outer shell. 1. M.S. Varnum et al., Phys. Rev. Lett. 84, 5153 (2000). 2. D.A. Callahan et al., Phys. of Plasmas 13, 56307 (2005). 3. P.A. Amendt et al., Phys. Rev. Lett. 94, 65004 (2005); private communication. 4. J.L. Milovich et al., Phys. of Plasmas 11, 1552 (2004). 5. I.L. Tregillis, this conference. 6. N.D. Delamater et al., this conference. *Work supported by US DOE/NNSA, performed at LANL, operated by LANS LLC under Contract DE-AC52-06NA25396.

Magelssen, G. R.; Delamater, N. D.; Gunderson, M. A.; Tregillis, I. L.; Schmitt, M. J.

2007-11-01

170

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.

171

Chemistry of the outer planets  

NASA Technical Reports Server (NTRS)

Various aspects were studied of past or present chemistry in the atmospheres of the outer planets and their satellites using lab simulations. Three areas were studied: (1) organic chemistry induced by kinetically hot hydrogen atoms in the region of Jupiter's atmosphere containing the ammonia cirrus clouds; (2) the conversion of NH3 into N2 by plasmas associated with entry of meteors and other objects into the atmosphere of early Titan; and (3) the synthesis of simple hydrocarbons and HCN by lightning in mixtures containing N2, CH4, and NH3 representing the atmospheres of Titan and the outer planets. The results showed that: (1) hot H2 atoms formed from the photodissociation of NH3 in Jupiter's atmosphere could account for some of the atmospheric chemistry in the ammonia cirrus cloud region; (2) the thermalization of hot H2 atoms in atmospheres predominated by molecular H is not as rapid as predicted by elastic collision theory; (3) the net quantum loss of NH3 in the presence of a 200 fold excess of H2 is 0.02, much higher than was expected from the amount of H2 present; (4) the conversion of NH3 into N2 in plasmas associated with infalling meteors is very efficient and rapid, and could account for most of the N2 present on Titan; (5) the yields of C2H2 and HCN from lightning induced chemistry in mixtures of CH4 and N2 is consistent with quenched thermodynamic models of the discharge core; and (6) photolysis induced by the UV light emitted by the gases in the hot plasmas may account for some, if not most, of the excess production of C2H6 and the more complex hydrocarbons.

Scattergood, Thomas W.

1992-01-01

172

Fabrication and optical absorption of size-tunable core-shell structured ZnO nanotube-CdTe arrays  

Microsoft Academic Search

Core-shell structured ZnO nanotube-CdTe nanocomposite arrays have been synthesized by one-step thermal evaporation of CdTe on single-crystalline ZnO nanotube arrays, which are on the ITO glass. The CdTe nanocrystal shells can be formed both at the inner and outer side of the ZnO nanotubes. It is found that the shell thickness is about 100 nm for the ZnO nanotubes with

Xina Wang; Yeming Xu; Hao Wang; Quan Li

2010-01-01

173

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

174

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

175

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

176

Overview: Hard Rock Penetration  

Microsoft Academic Search

The Hard Rock Penetration program is developing technology to reduce the costs of drilling and completing geothermal wells. Current projects include: lost circulation control, rock penetration mechanics, instrumentation, and industry\\/DOE cost shared projects of the Geothermal Drilling organization. Last year, a number of accomplishments were achieved in each of these areas. A new flow meter being developed to accurately measure

Dunn

1992-01-01

177

Overview - Hard Rock Penetration  

Microsoft Academic Search

The Hard Rock Penetration program is developing technology to reduce the costs of drilling and completing geothermal wells. Current projects include: lost circulation control, rock penetration mechanics, instrumentation, and industry\\/DOE cost shared projects of the Geothermal Drilling Organization. Last year, a number of accomplishments were achieved in each of these areas. A new flow meter being developed to accurately measure

Dunn; James C

1992-01-01

178

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

179

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

180

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

181

Hard Sphere Gas Model  

NSDL National Science Digital Library

The Ejs Hard Sphere Gas model displays a three-dimensional (ideal) gas made out of hard disks. Particles are initialized with a random speed and in a random direction and move with constant velocity until a collision occurs. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Hard Sphere Gas model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_newton_HardShpereGas.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for statistical mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-07-06

182

Optimized Double-Shell Ignition Designs for Various Pusher Materials  

NASA Astrophysics Data System (ADS)

The Lawrence Livermore National Laboratory (LLNL) is pursuing double-shell capsules as a non-cryogenic alternative path to ignition at the National Ignition Facility (NIF). Double-shell capsules consist of high pressure DT gas contained within a small metal pusher or inner shell with an inner radius of 300 to 400 microns. The pusher is supported by low density foam which is held within the ablator or outer shell. There are a number of materials that could be chosen for the pusher shell. It is important to determine which material will lead to the most robust ignition characteristics. It is also important to determine which materials will be easiest to fabricate and to fill with DT fuel. In order to address the issue of which pusher material offers the most robust ignition characteristics, a series of one dimensional numerical optimizations was done. For each choice of pusher material a configuration was found which maximized the calculated yield using the CALEICF code. The calculated yield was not the so-called clean yield but included the negative effects of a one dimensional mix model. This paper presents the results of these optimized double-shell ignition designs for pushers made out of: gold-copper, tungsten, tantalum, platinum-iridium, molybdenum, copper and titanium. Also presented is an analysis of the highest gas pressure that can be safely contained by each pusher material which is then compared with the required DT gas pressure for the double-shell design.

Tipton, Robert; Amendt, Peter; Milovich, Jose

2003-10-01

183

I Learned about Shells!  

NSDL National Science Digital Library

Through the use of nonfiction text, students will be able to share their prior knowledge and schema of shells. Students will practice gathering information from a text, help create a KEL chart through class and small group discussions, and will use the information learned to create an informative writing about shell animals.

Ryan, Kris

2012-06-26

184

Discrete Shells Origami  

Microsoft Academic Search

We introduce a way of simulating the creation of simple Origami (paper folding). The Origami is created in a thin shell simulation that realistically models the behavior and physical properties of paper. We demonstrate how to fold and crease the simulated paper wherever the user desires. This work employs cutting- edge advances in the field of discrete shell modeling to

Rob Burgoon; Zoë J. Wood; Eitan Grinspun

2006-01-01

185

SHELL METHOD DEMO GALLERY  

NSDL National Science Digital Library

This is a gallery of animations that can be used to illustrate the shell method for computing volumes of solids of revolution. The animations are designed to be used by the instructor in a classroom setting or by students as they acquire a visual background relating to solids of revolution and the steps of the shell method.

Roberts, Lila F.; Hill, David R.

2002-02-02

186

Outer trapped surfaces are dense near MOTSs  

NASA Astrophysics Data System (ADS)

We show that any vacuum initial data set containing a marginally outer trapped surface S and satisfying a ‘no KIDs’ condition can be perturbed near S so that S becomes strictly outer trapped in the new vacuum initial data set. This, together with the results in Eichmair et al (2012), gives a precise sense in which generic initial data containing marginally outer trapped surfaces lead to geodesically incomplete spacetimes.

Chru?ciel, Piotr T.; Galloway, Gregory J.

2014-02-01

187

High Rayleigh number rotating thermal convection with lateral heat-flux variations at the outer boundary  

NASA Astrophysics Data System (ADS)

The problem of thermally driven convection in a rapidly rotating spherical shell with homogeneous boundary conditions has been widely studied owing to its application to planetary cores. The dynamics of this system are determined by the Rayleigh number Ra, measuring the strength of the thermal driving force, the Prandtl number Pr, the ratio of viscous and thermal diffusion, and the Ekman number E, measuring the strength of the Coriolis force. The main challenges are to understand the behaviour of the system in the limits of small E and high Ra that characterise many core regions. An important modification to this homogeneous problem in the geophysical context is the addition of lateral variations in heat-flux at the outer boundary with amplitude measured by the nondimensional parameter q*, the ratio of peak-to-peak heat-flux variations on the boundary to the average outer boundary heat-flux. We study rapidly rotating convection in a spherical shell for Pr=1, 10-4 ? E ? 10-6, 0 ? q* ? 10 and Rayleigh numbers up to 400 times the critical value for the onset of homogeneous convection. Homogeneous (q*=0) and inhomogeneous solutions are compared in terms of their spatio-temporal behaviour and heat transfer properties. We also investigate the extent to which the effects of heat-flux anomalies imposed at the outer boundary penetrate into the deep interior of the shell.

Davies, C. J.

2013-12-01

188

Cohesive Elements for Shells  

NASA Technical Reports Server (NTRS)

A cohesive element for shell analysis is presented. The element can be used to simulate the initiation and growth of delaminations between stacked, non-coincident layers of shell elements. The procedure to construct the element accounts for the thickness offset by applying the kinematic relations of shell deformation to transform the stiffness and internal force of a zero-thickness cohesive element such that interfacial continuity between the layers is enforced. The procedure is demonstrated by simulating the response and failure of the Mixed Mode Bending test and a skin-stiffener debond specimen. In addition, it is shown that stacks of shell elements can be used to create effective models to predict the inplane and delamination failure modes of thick components. The results indicate that simple shell models can retain many of the necessary predictive attributes of much more complex 3D models while providing the computational efficiency that is necessary for design.

Davila, Carlos G.; Camanho, Pedro P.; Turon, Albert

2007-01-01

189

Specialized shell-breaking crab claws in Cretaceous seas.  

PubMed

Here we report on a large brachyuran crab species from the Late Cretaceous of Mexico that has claws indicative of highly specialized shell-breaking behaviour. This crab possessed dimorphic claws (the right larger than the left), armed with several broad teeth, including a curved tooth structure found at the base of the movable finger of the right claw. The curved tooth is similar to the one observed on claws of many living durophagous crabs that use it as a weapon to peel, crush or chip the edges of hard-shelled prey, particularly molluscs. These morphological traits suggest that specialized shell-breaking crab predators had evolved during the Cretaceous, which contradicts previous findings supporting an Early Cenozoic origin for specialized shell crushers within the brachyuran clade. PMID:18331975

Dietl, Gregory P; Vega, Francisco J

2008-06-23

190

The development of hard x-ray optics at MSFC  

NASA Astrophysics Data System (ADS)

We have developed the electroformed-nickel replication process to enable us to fabricate light-weight, high-quality mirrors for the hard-x-ray region. Two projects currently utilizing this technology are the production of 240 mirror shells, of diameters ranging from 50 to 94 mm, for our HERO balloon payload, and 150- and 230-mm-diameter shells for a prototype Constellation-X hard-x-ray telescope module. The challenge for the former is to fabricate, mount, align and fly a large number of high-resolution mirrors within the constraints of a modest budget. For the latter, the challenge is to maintain high angular resolution despite weight-budget-driven mirror shell thicknesses (100 ?m) which make the shells extremely sensitive to fabrication and handling stresses, and to ensure that the replication process does not degrade the ultra-smooth surface finish (~3 Å) required for eventual multilayer coatings. We present a progress report on these two programs.

Ramsey, Brian D.; Elsner, Ron F.; Engelhaupt, Darell; Gubarev, Mikhail V.; Kolodziejczak, Jeffery J.; O'Dell, Stephen L.; Speegle, Chet O.; Weisskopf, Martin C.

2004-02-01

191

Development of hard x-ray optics at MSFC  

NASA Astrophysics Data System (ADS)

We are fabricating optics for the hard-x-ray region using electroform nickel replication. The attraction of this process, which has been widely used elsewhere, is that the resulting full shell optics are inherently stable and thus can have very good angular resolution. The challenge with this process is to develop lightweight optics, and to keep down the costs of mandrel fabrication. We accomplished the former through the development of high-strength, low-stress nickel alloys that permit very thin, stable, shells without fabrication- and handling-induced deformations. For the latter, we have utilized inexpensive grinding and diamond turning to figure the mandrels and then purpose-built polishing machines to finish the surface. In-house plating tanks and a simple water-bath separation system complete the process. To date we have built shells ranging in size from 5 cm diameter to 50 cm, and with thickness down to 100 micron. For our HERO balloon program, we are fabricating over 200 iridium-coated shells, 250 microns thick, for hard-x-ray imaging up to 75 keV. Early test results on these have indicated half-power-diameters of 15 arcsec. The status of these developments will be reviewed.

Ramsey, Brian D.; Elsner, Ronald F.; Engelhaupt, Darell E.; O'Dell, Stephen L.; Speegle, Chet O.; Weisskopf, Martin C.

2003-03-01

192

Photoelectrochemical Behavior of Hierarchically Structured Si/WO3 Core-Shell Tandem Photoanodes.  

PubMed

WO3 thin films have been deposited in a hierarchically structured core-shell morphology, with the cores consisting of an array of Si microwires and the shells consisting of a controlled morphology WO3 layer. Porosity was introduced into the WO3 outer shell by using a self-assembled microsphere colloidal crystal as a mask during the deposition of the WO3 shell. Compared to conformal, unstructured WO3 shells on Si microwires, the hierarchically structured core-shell photoanodes exhibited enhanced near-visible spectral response behavior, due to increased light absorption and reduced distances over which photogenerated carriers were collected. The use of structured substrates also improved the growth rate of microsphere-based colloidal crystals and suggests strategies for the use of colloidal materials in large-scale applications. PMID:24678723

Coridan, Robert H; Arpin, Kevin A; Brunschwig, Bruce S; Braun, Paul V; Lewis, Nathan S

2014-05-14

193

Outer atmospheres of late stars  

SciTech Connect

The short-wavelength spectra of the stars UX Ari during flare activity and in the quiet state and RW Aur are analyzed. An independent determination of the electron density made it possible to draw the reliable conclusion from the line intensities that the extent of the transition region between chromosphere and corona is considerably greater for these stars and Capella than for the sun. Two groups of stars are distinguished: 1) rotating red dwarfs; 2) subgiants belonging to systems of the RS C Vn-type and T Tau-type stars. The former are characterized by coronal loops emitting in the x-ray region. The appearance of considerable fluxes in lines of ions with T/sub i/roughly-equal10/sup 5/ /sup 0/K in stars of the latter group without x-ray enhancement is connected with direct heating with T = 10/sup 4/--10/sup 5/ /sup 0/K and with the development of upward-intensifying motions. Such a dynamical model of the outer atmosphere differs considerably from the usually considered outflow of the solar-wind type, efficiently cooling the coronas of stars with low gravity.

Katsova, M.M.

1982-11-01

194

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

2013-10-18

195

76 FR 2919 - Outer Continental Shelf Official Protraction Diagram and Supplemental Official Outer Continental...  

Federal Register 2010, 2011, 2012, 2013

...Supplemental Official Outer Continental Shelf Block Diagrams AGENCY: Bureau of Ocean Energy...Supplemental Official Outer Continental Shelf Block Diagrams...Diagram (OPD) and Supplemental Official OCS Block Diagrams (SOBDs) located in the...

2011-01-18

196

Multimode short-wavelength perturbation growth studies for the National Ignition Facility double-shell ignition target designs  

NASA Astrophysics Data System (ADS)

Detailed multimode two-dimensional simulations of short-wavelength perturbations imposed on the material interfaces of a recently proposed indirect-drive double-shell ignition target [Amendt et al., Phys. Plasmas 9, 2221 (2002)] are presented. In this work, the effect of roughness imposed only on the surfaces of the inner shell is studied. Realistic perturbations are adopted from a measured spectrum of a glass capsule (as a surrogate for the high-Z inner shell). It is found that perturbing the inner surface of the inner shell shows minimal degradation in capsule performance. On the other hand, when roughness is imposed on the outer surface of the inner shell, the growth of large Legendre mode number perturbations (l>200) leads to shell breakup. Further analysis reveals a new pathway for the Rayleigh-Taylor (RT) instability. L-shell radiation (>8 keV) from the high-Z hohlraum wall ablates the outer surface of the high-Z inner shell, promoting large outward expansion which is reversed by the converging outer shell. The classic conditions for RT instability are met: low density material pushing onto the higher density inner shell. It is shown that this effect can be controlled by tamping the outward expansion of the inner shell with a variety of materials. Simulations with separate CH and Ti tampers demonstrate that the redesigned capsule can withstand perturbations with high mode number content without exhibiting shell breakup. Furthermore, the outstanding question of determining the cutoff mode number (lc) is addressed by performing simulations with successively larger maximum l, reaching values beyond 1000, and calculating the mix width of the pusher/tamper interface for the CH-tamped case. These numerical studies suggest that the mix width approaches a constant value close to 40% of the shell width at peak compression. While not a proof that lc has been found, this result suggests that a mix-relevant mode number may be within reach of current simulation capabilities.

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

2004-04-01

197

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

198

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

199

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

200

Dinosaurs, Diamonds, and Things from Outer Space, The Great Extinction  

NASA Astrophysics Data System (ADS)

This book explains, in a new and convincing theory, why most life on earth perished 65 million years ago. Intended for a broad audience, the book will also be of great interest to scientists - most of whom now agree that an object from outer space hit the earth with unimaginable force 65 million years ago. But what kind of object? Carlisle's scenario suggests that the event was a complex sequence, beginning with a nearby star turning supernova. The first effect of this on earth was the arrival of massive radiation, ten or twenty times the heat of the sun, igniting worldwide forest fires. The blast also perturbed the cloud of comets that surrounds the solar system, and some few centuries later one or more of these (loaded with interstellar diamonds) hit the earth, producing `nuclear winter' and causing a tremendous acidification of the oceans. Each step of this theory is backed up by hard evidence.

Carlisle, David Brez

201

Monodisperse and multilayer core–shell latex via surface cross-linking emulsion polymerization  

Microsoft Academic Search

We describe a method for the synthesis of phase-separated polymer latex with a monodisperse and multilayer core–shell (MMLCS) morphology by surface cross-linking emulsion polymerization. Poly(butyl acrylate)(PBA) was used for the seed and the core of the latex, the inner shell was poly(butyl acrylate-styrene) cross-linked with divinylbenzene (DVB) to avoid phase inversion, and the poly(methyl methacrylate-butyl acrylate-glycidyl methacrylate) was the outer

Yuanchun Mu; Teng Qiu; Xiaoyu Li

2009-01-01

202

Hard Metal Interstitial Lung Disease  

Microsoft Academic Search

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

M. Ángeles Montero; Javier de Gracia; Ferràn Morell

2010-01-01

203

Hard-core liquid-crystal fibers  

NASA Astrophysics Data System (ADS)

Self-organized liquid-crystal filamentary forms arise in many mixtures of the smectogen compounds at the transition from the isotropic melt. In some mixtures, a subsequent phase transition to the crystal or crystal smectic phase occurs at the core of the filaments. The resulting hard-core fibers act as anisotropic cylindrical lenses composed of the crystalline core surrounded by the nematic shell. In this work, the filaments, referred to as nematoids, have been obtained in several binary mixtures based on five mesogens: 4,4'-dipentylazoxybenzene, 4-dodecyloxy-4'- pentylbiphenyl, 4-hexyl-4'nonyloxybiphenyl, 4-acetyl-4'-dodecylbiphenyl and 4''-pentylcyclohexyl 4-(4'- pentylcyclohexyl) benzoate within a silicone oil as an inert liquid. To characterize the molecular arrangements within the nematoids, we present the microinterferometric measurements of the refractive index distribution within the fibers and its changes at the phase transitions.

Adamczyk, Antoni

2008-08-01

204

Hollow spherical shell manufacture  

DOEpatents

A process for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry.

O'Holleran, Thomas P. (Belleville, MI)

1991-01-01

205

Hollow spherical shell manufacture  

DOEpatents

A process is disclosed for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry. 3 figures.

O'Holleran, T.P.

1991-11-26

206

Shell Shock Structural Code.  

National Technical Information Service (NTIS)

SHELL SHOCK is a computer code that performs a frequency analysis and determines the static and dynamic response of any structure represented by mass, damping, and stiffness matrices. These matrices may be formed directly by the user, formed internally by...

J. E. Grant V. K. Gabrielson

1975-01-01

207

Name That Shell  

NSDL National Science Digital Library

The way a firework shell is designed and assembled determines the shape and color of a firework display. Choose a video clip and try to identify each firework variety in this interactive activity from the NOVA Web site.

Foundation, Wgbh E.

2004-01-29

208

Seafloor Manifestations of Fluid Venting and Shallow Gas-hydrate BSRs at the Outer Ridge of the Eastern Nankai Trough  

NASA Astrophysics Data System (ADS)

A multichannel seismic profile across the outer ridge of the eastern Nankai Trough shows abnormal shallow bottom simulating reflectors (BSRs) of gas hydrate in proportion to water depth and regional heat flow. Such shallow BSRs suggest fluid venting along the active fault estimated from swath bathymetry and subbottom profile survey. We conducted detail seafloor observation and sampling by JAMSTEC deep-tow video system, ROV "Dolphin 3K" and submersible "Shinkai 2000" in 2002. Dense clam colonies were observed around the summit of the ridge at a water depth of 1050m. Each colony mainly consists of Calyptogena sp., tubeworms and white bacterial mats, and sometimes includes small colony of Bathymodiolus sp. Existence of fossil cemented shell within active colony indicates repetition of methane seep at the same locality. Chimney-like or Pinnacle-like structures, composed of carbonate cemented sandstone, are observed at the northern slope of the ridge. These chimneys are regarded as ancient fluid conduits. Their exposure up to 2 meters above the seafloor indicates very active erosion after cold seepage. The seafloor near the summit is partly covered by thin sandy sediments and mostly exhibits carbonate pavement with a large number of NW-SE trending fractures. Shapes of some clam colonies are also elongated toward NW-SE suggesting effect of fracture patterns developed in the hard-ground below thin cover sediment. These fractures are probably caused by right lateral displacement of active faults across the ridge. It is inferred that up-dip fluid/gas migration through this fault causes pervasive fluid expulsion as well as shallow BSRs.

Ashi, J.; Saito, S.; Aoike, K.; Toki, T.; Kuramoto, S.; Henry, P.

2002-12-01

209

Corrasion of a remoulded cohesive bed by saltating littorinid shells  

NASA Astrophysics Data System (ADS)

Corrasion of a standard cohesive bed due to saltating gastropod shells of the species Littorina has been examined in a laboratory mini flume. The purpose of the study was to examine the effects of shell size and number on bed erosion rate. The movement of shells by flows explain why intertidal, glacial clays in the Bay of Fundy (which are covered in places with Littorinid shells) suffer erosion because bed erosion rate increased up to 20-fold with the introduction of a single shell to the flume (27 m -2). The standard bed was made of potters clay which had an erosion threshold of 0.19 Pa and a fluid-induced erosion rate Eo=0.072( Uy- Ucrit) gm -2 s -1, where Uy is the azimuthal current speed at height y=0.10 m. Shells of seven differing sizes ( ds) were used to define the process of erosion by shell impacts. The threshold for shell motion ( Ugcrit) was linearly related to shell size in the form: Ugcrit=9.17×10 -3 ds-0.22 m s -1. Motion began by intermittent rolling, followed by continuous rolling and then by saltation. The shell speed in saltation was 68% that of Uy, thus 32% of the horizontal shell momentum was transmitted to the bed. The length/height ratio of saltations was 6.3, and was constant for all sizes, and the mean saltation frequency was 1.7 s -1. The shell erosion rate ( Es) increased with shell diameter for both the rolling and saltating phases. During the rolling phase, Es was up to 5 times greater than Eo at the same current speed. During saltation, Es was up to 20 times greater than Eo at the same current speed. The effect of shell number (1-7) was examined for the 7-10 mm size class. During rolling, Es increased linearly with shell number. For the saltating phase, Es increased in an asymptotic fashion, suggesting that groups of saltating shells affect the erosion process differently than single shells. The ballistic momentum flux ( T) of saltating shells is highly dependent on the area of impact ( Ag), which in the case of the littorinids, is along the rounded outer lip of the aperture (measured to be 0.5% of the nominal cross-sectional area of the shell). T increased with shell mass ( Mg) and current speed ( Uy). Below 0.29 m s -1, T< ?o; for 0.29< Uy<0.35 m s -1, T? ?o; and for Uy>0.35 m s -1, T> ?o where ?o is the fluid-induced shear stress. The total erosion rate ( Etot= Es+ Eo) was compared to the excess total bed shear stress ( ?tot- ?crit) and found to be linearly related in the form: E tot=0.010 [? tot-? crit] gm -2 s -1. Es appeared to be in linear continuity with Eo if the impact area was set to 0.05% of the estimated shell nominal cross-sectional area.

Amos, C. L.; Sutherland, T. F.; Cloutier, D.; Patterson, S.

2000-07-01

210

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

211

RESISTANCE OF THE SHELL MEMBRANE AND MINERAL LAYER TO DIFFUSION OF OXYGEN AND WATER IN FLEXIBLE-SHELLED EGGS OF THE SNAPPING TURTLE (CHELYDRA SERPENTINA)  

Microsoft Academic Search

At oviposition, flexible eggshells of many turtles have an outer mineral layer and an inner membrane layer of approximately equal thickness. We measured conductances of both layers to H20 and 02 at various levels of eggshell hydration. Both the mineral layer of the eggshell and the shell membrane offer significant resistance to diffusion of water vapor and oxygen in eggshells

MARTIN E. FEDER; SALLY L. SATEL; ALLEN G. GIBBS

212

Large scale production of yolk-shell ?-tricalcium phosphate powders, and their bioactivities as novel bone substitutes.  

PubMed

This paper proposes the production of yolk-shell structured ?-tricalcium phosphate (?-TCP) powders using a spray-drying method, suitable for commercial scale production. Spray-dried precursor powders, consisting of calcium-phosphate salts and each of the various carbon source materials, are combusted in an oxygen atmosphere to obtain a yolk-shell structure. Only dextrin among the carbon source materials investigated shows promise in the production of ?-TCP yolk-shell powders. By evaluating their apatite-forming capacity in simulated body fluid, the outstanding bioactivity of ?-TCP yolk-shell powders is confirmed: numerous acicular and newly formed hydroxyl carbonate apatite crystals cover the entire ?-TCP surface after a single day of soaking. These crystals are observed on both the outer and inner surfaces of the shells, and on the outer surface of the core, which is encouraging for its potential use as a bone grafting material. PMID:25005151

Cho, Jung Sang; Lee, Jong-Heun; Kang, Yun Chan

2014-07-23

213

Proton microprobe studies of fluorine distributions in mollusc shells  

NASA Astrophysics Data System (ADS)

Since the mineral in mollusc shells, calcium carbonate, has no site in the crystal for a fluorine ion we would expect this element to occur as only a trace element in shells. Our measurements have revealed something quite different: in seven of eight species we found in both aragonite and calcite shells some growth layers with concentrations as high as 150 ppm by weight, and in a common species of oyster layers about 0.15 mm wide with up to 1700 ppm; this is more than occurs in human tooth enamel, whose apatite has an affinity for fluorine ions. The overall pattern of fluorine was quite different to that of the other minor element strontium, although in several species peaks in the two distributions occurred in exactly the same layers, showing that they had a common cause. The highest fluorine concentration is usually found near the outer surface of the oldest part of the shell, but the evidence suggests that it was deposited during calcification and did not diffuse in aftewards from seawater; for example in the youngest parts of the shell the distribution is several times broader. Two species of oyster (with calcite shells) showed completely different fluorine patterns: the flat oyster Tiostrea had a constant level of about 30 ppm, whereas the Pacific oyster Crassotreh gigas revealed isolated narrow layers with concentrations as high as 1700 ppm. These two species have quite different reproductive behaviour and it is possible that Sr and F markings are formed during the spawning period.

Coote, G. E.; Trompetter, W. J.

1995-09-01

214

A rigid and weathered ice shell on Titan.  

PubMed

Several lines of evidence suggest that Saturn's largest moon, Titan, has a global subsurface ocean beneath an outer ice shell 50 to 200?kilometres 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. PMID:23985871

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

2013-08-29

215

Iron Oxide Versus Fe Pt \\/Fe O : Improved Magnetic Properties of Core\\/Shell Nanoparticles for Biomedical Applications  

Microsoft Academic Search

In this paper, synthesis of the Fe55Pt45\\/Fe3O4 core\\/shell structured nanoparticles using the modified polyol process combined with the seed-mediated growth method is reported. Iron oxide shell thickness was tuned controlling the Fe(acac) 3\\/FePt seeds in the reaction medium. Annealing of the core\\/shell structure leads to iron-rich layer formation around the hard FePt phase in the nanoparticle core. However, the 2

L. C. Varanda; M. Imaizumi; F. J. Santos; M. Jafelicci Jr.

2008-01-01

216

Improved Method of Design for Folding Inflatable Shells  

NASA Technical Reports Server (NTRS)

An improved method of designing complexly shaped inflatable shells to be assembled from gores was conceived for original application to the inflatable outer shell of a developmental habitable spacecraft module having a cylindrical mid-length section with toroidal end caps. The method is also applicable to inflatable shells of various shapes for terrestrial use. The method addresses problems associated with the assembly, folding, transport, and deployment of inflatable shells that may comprise multiple layers and have complex shapes that can include such doubly curved surfaces as toroids and spheres. One particularly difficult problem is that of mathematically defining fold lines on a gore pattern in a double- curvature region. Moreover, because the fold lines in a double-curvature region tend to be curved, there is a practical problem of how to implement the folds. Another problem is that of modifying the basic gore shapes and sizes for the various layers so that when they are folded as part of the integral structure, they do not mechanically interfere with each other at the fold lines. Heretofore, it has been a common practice to design an inflatable shell to be assembled in the deployed configuration, without regard for the need to fold it into compact form. Typically, the result has been that folding has been a difficult, time-consuming process resulting in a An improved method of designing complexly shaped inflatable shells to be assembled from gores was conceived for original application to the inflatable outer shell of a developmental habitable spacecraft module having a cylindrical mid-length section with toroidal end caps. The method is also applicable to inflatable shells of various shapes for terrestrial use. The method addresses problems associated with the assembly, folding, transport, and deployment of inflatable shells that may comprise multiple layers and have complex shapes that can include such doubly curved surfaces as toroids and spheres. One particularly difficult problem is that of mathematically defining fold lines on a gore pattern in a double- curvature region. Moreover, because the fold lines in a double-curvature region tend to be curved, there is a practical problem of how to implement the folds. Another problem is that of modifying the basic gore shapes and sizes for the various layers so that when they are folded as part of the integral structure, they do not mechanically interfere with each other at the fold lines. Heretofore, it has been a common practice to design an inflatable shell to be assembled in the deployed configuration, without regard for the need to fold it into compact form. Typically, the result has been that folding has been a difficult, time-consuming process resulting in a

Johnson, Christopher J.

2009-01-01

217

Effects of alga polysaccharide capsule shells on in-vivo bioavailability and disintegration  

NASA Astrophysics Data System (ADS)

Gelatin has been used in hard capsule shells for more than a century, and some shortcomings have appeared, such as high moisture content and risk of transmitting diseases of animal origin to people. Based on available studies regarding gelatin and vegetable shells, we developed a new type of algal polysaccharide capsule (APPC) shells. To test whether our products can replace commercial gelatin shells, we measured in-vivo plasma concentration of 12 selected volunteers with a model drug, ibuprofen, using high performance liquid chromatography (HPLC), by calculating the relative bioavailability of APPC and Qualicaps® referenced to gelatin capsules and assessing bioequivalence of the three types of shells, and calculated pharmacokinetic parameters with the software DAS 2.0 (China). The results show that APPC shells possess bioequivalence with Qualicaps® and gelatin shells. Moreover, the disintegration behavior of four types of shells (APPC, Vegcaps®, Qualicaps® and gelatin shells) with the content of lactose and radioactive element (99mTc) was observed via gamma-scintigraphic images. The bioavailability and gamma-scintigraphic studies showed that APPC was not statistically different from other vegetable and gelatin capsule shells with respect to in-vivo behavior. Hence, it can be concluded that APPCs are exchangeable with other vegetable and gelatin shells.

Li, Ting; Guo, Shuju; Ma, Lin; Yuan, Yi; Han, Lijun

2012-01-01

218

Geographic variation of shell bionts in the deep-sea snail Gaza  

NASA Astrophysics Data System (ADS)

Recent studies of bathyal environments indicate that microhabitats contribute significantly to biodiversity. We suggest that microhabitats may also be useful in direct comparisons of biotic diversity patterns across large areas. Using a technique developed by palaeontologists, we document the diversity and abundance of taxa occurring on the hard substrate provided by gastropod shells of the bathyal (200 m) trochid gastropod Gaza. Because the shell surfaces are comparable, shell-associated biota and their diversity may be contrasted across basins with relatively few compounding variables. Animals found attached to the outside of the shells, epibionts, included folliculinids, encrusting bryozoans and foraminifera; within the shell, endobiontic spionid polychaetes had occupied the columella of the shell, apparently destroying both the protoconch and part of the shell's base. Both types of bionts were common on shells from continental margins of North and South America but were wholly absent on shells from the Lesser Antilles. Hypotheses that shell depth distributions (372-910 m) and shell age, biont dispersal potential and biotic interactions contribute to the large-scale differences in biont distribution are considered but rejected in favour of the hypothesis that terrigenous sediments and their associated nutrients are primary contributors to the observed geographic pattern.

Voight, Janet R.; Walker, Sally E.

1995-08-01

219

Hard noncommutative loops resummation.  

PubMed

The noncommutative version of the Euclidean g2phi4 theory is considered. By using Wilsonian flow equations the ultraviolet renormalizability can be proved to all orders in perturbation theory. On the other hand, the infrared sector cannot be treated perturbatively and requires a resummation of the leading divergences in the two-point function. This is analogous to what is done in the hard thermal loops resummation of finite temperature field theory. Next-to-leading order corrections to the self-energy are computed, resulting in O(g3) contributions in the massless case, and O(g6logg2) in the massive one. PMID:11863880

Griguolo, Luca; Pietroni, Massimo

2002-02-18

220

Visual indication of mechanical damage using core-shell microcapsules.  

PubMed

We report a new core-shell microcapsule system for the visual detection of mechanical damage. The core material, 1,3,5,7-cyclooctatetraene, is a conjugated cyclic olefin and a precursor to intensely colored polyacetylene. A combination of poly(urea-formaldehyde) and polyurethane is required to effectively encapsulate the volatile core material. Increasing the outer shell wall thickness and including a core-side prepolymer improves the thermal stability and free-flowing nature of these capsules, which tend to leach and rupture with thinner shell walls. Capsules ruptured in the presence of the Grubbs-Love ruthenium catalyst show immediate color change from nearly colorless to red-orange and dark purple over time, and color change in thin films resulted from scratch damage. PMID:22114767

Odom, Susan A; Jackson, Aaron C; Prokup, Alex M; Chayanupatkul, Sarut; Sottos, Nancy R; White, Scott R; Moore, Jeffrey S

2011-12-01

221

Is the Outer Solar System Really Chaotic?  

Microsoft Academic Search

The existence of chaos among the system of Jovian planets (Jupiter, Saturn, Uranus, and Neptune) is not yet firmly established. Although Laskar originally found no chaos in the outer Solar System, his \\

Wayne B. Hayes

2006-01-01

222

Turbulent Boundary Layer Inner-Outer Interactions.  

National Technical Information Service (NTIS)

A summary of work performed to study the interactions between the inner and outer regions of a turbulent boundary layer is presented. The interactions were studied by observing the response of the boundary layer to different perturbations. The inner regio...

D. G. Bogard C. Lim A. Kohli

1993-01-01

223

Outer planet probe engineering model structural tests  

NASA Technical Reports Server (NTRS)

A series of proof of concept structural tests was performed on an engineering model of the Outer Planets Atmospheric Entry Probe. The tests consisted of pyrotechnic shock, dynamic and static loadings. The tests partially verified the structural concept.

Smittkamp, J. A.; Gustin, W. H.; Griffin, M. W.

1977-01-01

224

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

225

Uranyl peroxide oxalate cage and core-shell clusters containing 50 and 120 uranyl ions.  

PubMed

Cage clusters built from uranyl hexagonal bipyramids and oxalate ligands crystallize from slightly acidic aqueous solution under ambient conditions, facilitating structure analysis. Each cluster contains uranyl ions coordinated by peroxo ligands in a bidentate configuration. Uranyl ions are bridged by shared peroxo ligands, oxalate ligands, or through hydroxyl groups. U(50)Ox(20) contains 50 uranyl ions and 20 oxalate groups and is a topological derivative of the U(50) cage cluster that has a fullerene topology. U(120)Ox(90) contains 120 uranyl ions and 90 oxalate groups and is the largest and highest mass cluster containing uranyl ions that has been reported. It has a core-shell structure, in which the inner shell (core) consists of a cluster of 60 uranyl ions and 30 oxalate groups, identical to U(60)Ox(30), with a fullerene topology. The outer shell contains 12 identical units that each consist of five uranyl hexagonal bipyramids that are linked to form a ring (topological pentagon), with each uranyl ion also coordinated by a side-on nonbridging oxalate group. The five-membered rings of the inner and outer shells (the topological pentagons) are in correspondence and are linked through K cations. The inner shell topology has therefore templated the location of the outer shell rings, and the K counterions assume a structure-directing role. Small-angle X-ray scattering data demonstrated U(50)Ox(20) remains intact in aqueous solution upon dissolution. In the case of clusters of U(120)Ox(90), the scattering data for dissolved crystals indicates the U(60)Ox(30) core persists in solution, although the outer rings of uranyl bipyramids contained in the U(120)Ox(90) core-shell cluster appear to detach from the cluster when crystals are dissolved in water. PMID:22296269

Ling, Jie; Qiu, Jie; Burns, Peter C

2012-02-20

226

Outer membrane protein profiles of Haemophilus pleuropneumoniae.  

PubMed Central

Outer membrane protein profiles of Haemophilus pleuropneumoniae were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cells were disrupted by sonication, and outer membrane-enriched fractions were prepared by differential centrifugation and selective solubilization of the inner membrane with sodium N-lauroyl sarcosinate. Colony type, growth medium, time of harvest, and in vitro or in vivo passage had no appreciable effect on the protein profiles of the strains examined. Seven patterns were distinguished among the reference strains of the nine capsular serotypes. These patterns were based on the mobility of the major outer membrane proteins migrating in the 39,000- to 44,000-molecular-weight region of the gel, a 16K to 16.5K protein, and a heat-modifiable 29K protein. Strains of serotypes 1 and 9 had identical outer membrane protein profiles, as did strains of serotypes 2 and 6. The reference strains of the remaining five serotypes each had a distinct pattern. The outer membrane protein profiles of 95 field isolates belonging to serotypes 1, 5, 7, and 9 from swine in the midwestern United States were determined and compared with the reference patterns. The results indicate that the population of H. pleuropneumoniae is clonal, with three predominant clones distinguished by both serotype and outer membrane protein profile responsible for the majority of H. pleuropneumoniae disease occurring in swine in the United States. Images

Rapp, V J; Munson, R S; Ross, R F

1986-01-01

227

Sound Transmission through Cylindrical Shell Structures Excited by Boundary Layer Pressure Fluctuations  

NASA Technical Reports Server (NTRS)

This paper examines sound transmission into two concentric cylindrical sandwich shells subject to turbulent flow on the exterior surface of the outer shell. The interior of the shells is filled with fluid medium and there is an airgap between the shells in the annular space. The description of the pressure field is based on the cross-spectral density formulation of Corcos, Maestrello, and Efimtsov models of the turbulent boundary layer. The classical thin shell theory and the first-order shear deformation theory are applied for the inner and outer shells, respectively. Modal expansion and the Galerkin approach are used to obtain closed-form solutions for the shell displacements and the radiation and transmission pressures in the cavities including both the annular space and the interior. The average spectral density of the structural responses and the transmitted interior pressures are expressed explicitly in terms of the summation of the cross-spectral density of generalized force induced by the boundary layer turbulence. The effects of acoustic and hydrodynamic coincidences on the spectral density are observed. Numerical examples are presented to illustrate the method for both subsonic and supersonic flows.

Tang, Yvette Y.; Silcox, Richard J.; Robinson, Jay H.

1996-01-01

228

Quantitative Ray Methods for Scattering of Sound by Spherical Shells.  

NASA Astrophysics Data System (ADS)

The application of ray methods to the scattering of high-frequency plane waves from evacuated elastic spherical shells is investigated. The investigation of ray methods for spherical shells is a precursor to the application of such methods to shells having more complicated shapes. The scattered pressure in the farfield of the shell is p _{sc} = p_{i}(a/2r)f( theta)exp(ikr) where p_{i } is the plane wave amplitude. The outer radius of the shell is a, h = a - b is the shell's thickness, and r is the distance to an observation point. Ray models are developed to synthesize the form function f( theta,ka) where k is the wavenumber of the incident wave and theta is the scattering angle. The forward scattering amplitude, f(theta = 0), is related to the extinction cross section, sigma_{e}, by the optical theorem. If the absorption by the scatterer is negligible, then sigma_{rm e} is equal to the scattering cross section sigma_{t}. A ray synthesis partitions f(theta = 0) into a component for ordinary forward diffraction about the shell, f_{FD}, and contributions from surface guided elastic waves. For high -frequency scattering, the relevant surface guided elastic waves are leaky Lamb waves. A similar ray synthesis of the backscattering amplitude f(theta=pi) contains a specular reflection component, f _{^}(theta=pi), and leaky Lamb wave contributions. A generalization of the geometrical theory of diffraction is employed to synthesize f_{l}(theta=0, {ka }) and f_{l}(theta= pi, {ka}) for the lth leaky Lamb wave contribution. The syntheses for forward and backwards scattering correctly describe the leaky Lamb wave contributions and are expressible in a Fabry-Perot resonator form. While the ray description of backscattering ordinarily accurately reproduces exact computations and experiments with tone burst, certain anomalies are discussed. A ray synthesis of f_{^} demonstrates a significant longitudinal resonance effect when k _{L}h = npi,n = 1, 2,..., where k_ {L} = omega/c _{L} is the longitudinal wavenumber within the shell. The analysis of f_{^ } is for an elastic material with vanishing shear velocity. The relevant range of ka is 7 <=q ka <=q 100. The shell is surrounded by water and is composed of 440c stainless steel with inner-to-outer radii ratio b/a = 0.838.

Kargl, Steven Gregory

1990-01-01

229

Sensational spherical shells  

NASA Technical Reports Server (NTRS)

Fluid-dynamic and capillary forces can be used to form nearly perfect, very small spherical shells when a liquid that can solidify is passed through an annular die to form an annular jet. Gravity and certain properties of even the most ideal materials, however, can cause slight asymmetries. The primary objective of the present work is the control of this shell formation process in earth laboratories rather than space microgravity, through the development of facilities and methods that minimize the deleterious effects of gravity, aerodynamic drag, and uncontrolled cooling. The spherical shells thus produced can be used in insulation, recyclable filter materials, fire retardants, explosives, heat transport slurries, shock-absorbing armor, and solid rocket motors.

Lee, M. C.; Kendall, J. M., Jr.; Bahrami, P. A.; Wang, T. G.

1986-01-01

230

Hard metal composition  

SciTech Connect

This patent describes a hard composition of matter having a Rockwell A hardness value of at least approximately 85, comprising the compressed and densified reaction product of: a minor amount of a boron carbide component selected from the group consisting of (a) boron carbide and (b) boron and carbon, the boron and carbon being present in amounts sufficient to form boron carbide in situ, wherein the boron carbide component consists essentially of B/sub 4/C; a major amount of a metal mixture consisting essentially of: (a) a first metal component selected from the group consisting of tungsten and molybdenum and mixtures thereof, and (b) a second metal component selected from the group consisting of nickel and iron and mixtures thereof; wherein the minor amount of the boron carbide component is between 3% and 6% by weight of the composition of matter when the first metal component is tungsten. The minor amount of the boron carbide component is between 6% and 10% by weight of the composition when the first metal component is molybdenum. The boron carbide component is between 3% and 10% when the first metal component is a mixture of tungsten and molybdenum, with the remainder of the composition being formed of the metal mixture, and wherein the first metal component is from 70% to less than about 90% by weight of the metal mixture when the first metal component is tungsten, and wherein the first metal component is from 72% to less than about 90% by weight of the metal mixture when the first metal component is molybdenum.

Sheinberg, H.

1986-12-02

231

Interactive design of large end rings on stiffened conical shells using composites  

NASA Technical Reports Server (NTRS)

Design study methods and results for a composite reinforced base ring for the conical aeroshell structure of the planetary lander vehicle for Project Viking, an unmanned mission to Mars, are presented. The aeroshell is a ring and stringer-stiffened conical shell structure having a half angle of 70 degrees with a large base ring mounted at the outer edge of the cone and a large pay-load ring in the interior with many smaller rings spaced along the inside shell surface. The purpose of the structure is to develop the aerodynamic drag required to decelerate the lander in the Mars atmosphere to facilitiate a soft landing. The design of a shell structure of this complexity requires the use of the latest technology available in a large general-purpose shell buckling program. The large general-purpose non-linear shell buckling program (BOSOR 2) which was used for this purpose is described.

Davis, R. C.; Cooper, P. A.

1974-01-01

232

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

233

Shell effects in Pb(p,xn) preequilibrium neutron emission  

SciTech Connect

The /sup 204/, 206, 207, 208Pb(p,xn) reactions have been investigated at E/sub p/ = 25.5 MeV. The hard energy spectra and the structures observed in the preequilibrium continuum are attributed to the nearby double shell closure. Application of semiclassical preequilibrium models requires the reduction of the state density g and/or the use of (1p)(1n)/sup -1/ state densities based on realistic single particle level schemes.

Harder, K.; Kaminsky, A.; Mordhorst, E.; Scobel, W.; Trabandt, M.

1987-08-01

234

The application of shell strength measurements in Egg Shell quality determination  

Microsoft Academic Search

Comparisons of shell thickness, specific gravity and shell strength (breaking strength and shell deformation under load) for individual loads have been made and correlation coefficients determined. The relationship between egg size, shell strength and shell deformation have been investigated.Shell strength has been correlated with shell thickness and specific gravity, but due to the complex nature of shell strength, it has

M. J. Gaisford

1965-01-01

235

Photoelectron Angular Distributions of s Electrons in Open-Shell Atoms  

Microsoft Academic Search

It is shown that the photoelectron angular distribution of s electrons in an open-shell atom, having outer configuration ns2npq, is not described by the asymmetry parameter beta=2, as predicted by more approximate theories, but has dramatic variations with energy even within LS coupling. Calculations for the 3s subshell in Cl are presented as an example.

Anthony F. Starace; Robert H. Rast; Steven T. Manson

1977-01-01

236

Photoelectron angular distributions of s electrons in open-shell atoms  

Microsoft Academic Search

It is shown that the photoelectron angular distribution of s electrons in an open-shell atom, having outer configuration ns²np\\/sup q\\/, is not described by the asymmetry parameter ..beta.. = 2, as predicted by more approximate theories, but has dramatic variations with energy even within LS coupling. Calculations for the 3s subshell in Cl are presented as an example.

Anthony Starace; Robert Rast; Steven Manson

1977-01-01

237

Strain history of ice shells of the Galilean satellites from radar detection of crystal orientation fabric  

Microsoft Academic Search

Orbital radar sounding has been suggested as a means of determining the subsurface thermal and physical structure of the outer ice I shells of the Galilean satellites. At radar frequencies, the dielectric permittivity of single- and polycrystalline water ice I is anisotropic. Crystal orientation fabric (COF), which is indicative of strain history, can be unambiguously detected by comparing the received

Amy C. Barr; David E. Stillman

2011-01-01

238

Instability Localized at the Inner Surface of an Imploding Spherical Shell.  

National Technical Information Service (NTIS)

It is shown that in an imploding spherical shell the surface instabilities are of two different types. The first, which occurs at the outer surfaces, is the Rayleigh-Taylor instability. The second instability occurs at the inner surface. This latter insta...

S. J. Han

1983-01-01

239

Postbuckling of internal pressure loaded FGM cylindrical shells surrounded by an elastic medium  

Microsoft Academic Search

This paper presents a study on the postbuckling response of a functionally graded cylindrical shell of finite length embedded in a large outer elastic medium and subjected to internal pressure in thermal environments. The surrounding elastic medium is modeled as a tensionless Pasternak foundation that reacts in compression only. The postbuckling analysis is based on a higher order shear deformation

Hui-Shen Shen; Jie Yang; Sritawat Kitipornchai

2010-01-01

240

Laser sintering (SLS) of hard metal powders for abrasion resistant coatings  

Microsoft Academic Search

Selective laser sintering (SLS), one of the new RP, RT and RM techniques, may be able to provide a process to form hard coating, which increases the life of machine parts in abrasive conditions. It is known that cemented carbide (WC–Co) parts can be made by this technology, although not to full density. A porous shell of WC–Co, shaped to

K Maeda; T. H. C Childs

2004-01-01

241

A New 'Shell Casting' Technic.  

National Technical Information Service (NTIS)

A new shell investment was formulated that hardened rapidly enough so that consecutive layers could be applied to a wax pattern without requiring intermediate drying cycles between each layer. This new 'shell casting investment' is a two component system....

E. R. Dootz R. G. Craig F. A. Peyton

1966-01-01

242

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

243

Shell radiance texture functions  

Microsoft Academic Search

The appearance of an inhomogeneous translu- cent material depends substantially on its volumetric variations and their efiects upon subsurface scattering. For e-cient rendering that accounts for both surface mesostructures and volumetric variations of such mate- rials, shell texture functions have precomputed irradi- ance within a volume with respect to incoming illumina- tion, but even with this irradiance data a fair

Ying Song; Yanyun Chen; Xin Tong; Stephen Lin; Jiaoying Shi; Baining Guo; Heung-yeung Shum

2005-01-01

244

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

245

Shell Higher Olefins Process.  

ERIC Educational Resources Information Center

Shows how olefin isomerization and the exotic olefin metathesis reaction can be harnessed in industrial processes. Indicates that the Shell Higher Olefins Process makes use of organometallic catalysts to manufacture alpha-olefins and internal carbon-11 through carbon-14 alkenes in a flexible fashion that can be adjusted to market needs. (JN)

Lutz, E. F.

1986-01-01

246

EOS TPC analysis shell.  

National Technical Information Service (NTIS)

Key features of the general purpose event-based-data analysis shell (TAS) for the EOS TPC at LBL are described including the code development/code management procedures used. The architecture is designed with a view towards a distributed and multi-process...

D. L. Olson

1991-01-01

247

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

248

MHD processes in the outer heliosphere  

NASA Technical Reports Server (NTRS)

The magnetic field measurements from Voyager and the magnetohydrodynamic (MHD) processes in the outer heliosphere are reviewed. A bibliography of the experimental and theoretical work concerning magnetic fields and plasmas observed in the outer heliosphere is given. Emphasis in this review is on basic concepts and dynamical processes involving the magnetic field. The theory that serves to explain and unify the interplanetary magnetic field and plasma observations is magnetohydrodynamics. Basic physical processes and observations that relate directly to solutions of the MHD equations are emphasized, but obtaining solutions of this complex system of equations involves various assumptions and approximations. The spatial and temporal complexity of the outer heliosphere and some approaches for dealing with this complexity are discussed.

Burlaga, L. F.

1984-01-01

249

TRAO Outer Galaxy Survey in 13CO  

NASA Astrophysics Data System (ADS)

We present a result of 13CO(1-0) survey toward the Outer Galactic Plane using the multi-beam receiver system installed on the 14 m telescope at Taeduk Radio Astronomy Observatory(TRAO). Our target region is from l=120o to 140o and b=-1o to +1o, which is the part of the 12CO Outer Galactic Plane Survey (Heyer et al. 1998). All data are on 50" grid, and the beamsize is also 50". Velocity resolution is 0.63 km/sec, and the total velocity range is from -150 km/sec to 100 km/sec. A total of 23,000 spectra were obtained. The rms noise is about 0.15 K per channel for unsmoothed raw data. We will present a few initial results of the survey database, comparing with 12CO Outer Galactic Plane Survey database.

Lee, Youngung

2014-06-01

250

Origin of the Outer Solar System  

NASA Technical Reports Server (NTRS)

Our ongoing research program combines extensive deep and wide-field observations using a variety of observational platforms with numerical studies of the dynamics of small bodies in the outer solar system in order to advance the main scientific goals of the community studying the Kuiper belt and the outer solar system. These include: (1) determining the relative populations of the known classes of KBOs as well as other possible classes; (2) determining the size distributions or luminosity function of the individual populations or the Kuiper belt as a whole; (3) determining the inclinations distributions of these populations; (4) establishing the radial extent of the Kuiper belt; (5) measuring and relating the physical properties of different types of KBOs to those of other solar system bodies; and, (6) completing our systematic inventory of the satellites of the outer planets.

Holman, Matthew J. (Principal Investigator); Boyce, Joseph (Technical Monitor)

2003-01-01

251

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

252

Surface scattering of core-shell particles with anisotropic shell.  

PubMed

The Bobbert-Vlieger solution to light scattering of a spherical particle suspended above a surface is extended to model the scattering of core-shell structures with anisotropic shell. Numerical modeling demonstrates that ellipsometry has potential to resolve particle shell anisotropy down to 1.8×10(-4) for SiO(2)@Au core-shell particles in air with 50 nm core diameter and 10 nm shell thickness deposited on a silicon Si [100] substrate with a density of 1???m(-2). Application of the Ibrahim and Bashara criterion for ellipsometer parameter cross correlation identifies variable-angle ellipsometry as a viable experimental approach to separate particle core radius and shell thickness from the shell anisotropy. Ellipsometry is also identified as an alternative technique for determination of liposome anisotropy and for the study of liposome fusion with a substrate in the formation process of supported lipid bilayers. PMID:24561952

De Beule, Pieter A A

2014-01-01

253

Rollable Thin-Shell Nanolaminate Mirrors  

NASA Technical Reports Server (NTRS)

A class of lightweight, deployable, thin-shell, curved mirrors with built-in precise-shape-control actuators is being developed for high-resolution scientific imaging. This technology incorporates a combination of advanced design concepts in actuation and membrane optics that, heretofore, have been considered as separate innovations. These mirrors are conceived to be stowed compactly in a launch shroud and transported aboard spacecraft, then deployed in outer space to required precise shapes at much larger dimensions (diameters of the order of meters or tens of meters). A typical shell rollable mirror structure would include: (1) a flexible single- or multiple-layer face sheet that would include an integrated reflective surface layer that would constitute the mirror; (2) structural supports in the form of stiffeners made of a shape-memory alloy (SMA); and (3) piezoelectric actuators. The actuators, together with an electronic control subsystem, would implement a concept of hierarchical distributed control, in which (1) the SMA actuators would be used for global shape control and would generate the large deformations needed for the deployment process and (2) the piezoelectric actuators would generate smaller deformations and would be used primarily to effect fine local control of the shape of the mirror.

Hickey, Gregory; Lih, Shyh-Shiuh; Barbee, Troy, Jr.

2003-01-01

254

Rebuilding of the Earth's outer electron belt during 8-10 October 2012  

NASA Astrophysics Data System (ADS)

Geomagnetic storms often include strong magnetospheric convection caused by sustained periods of southward interplanetary magnetic field. During periods of strong convection, the Alfvén layer, which separates the region of sunward convection from closed drift shells, is displaced earthward allowing plasma sheet particles with energies in the hundreds of keV direct access inside of geosynchronous. Subsequent outward motion of the Alfvén boundary and adiabatic energization during storm recovery traps plasma sheet electrons on closed drift shells providing a seed population for the outer radiation belts. In situ observations of the 8-10 October 2012 geomagnetic storm and MHD test particle simulations illustrate the morphology of this process. Data and modeling results support the conclusion that recovery of ~ 1 MeV electrons at geosynchronous is mainly due to global convection and dipolarization associated injections from the plasma sheet.

Kress, B. T.; Hudson, M. K.; Paral, J.

2014-02-01

255

76 FR 4129 - Notice on Outer Continental Shelf Oil and Gas Lease Sales  

Federal Register 2010, 2011, 2012, 2013

...Shell Oil Company. Shell Offshore Inc. SWEPI LP. Shell Frontier Oil & Gas Inc. Shell Onshore Ventures Inc. SOI Finance Inc. Shell Rocky Mountain Production LLC. Shell Gulf of Mexico Inc. East Resources Management, LLC. Group...

2011-01-24

256

Can the Ice I Shells of Icy Satellites Convect?  

NASA Astrophysics Data System (ADS)

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, and by extrapolation to midsized icy satellites as well. Conductive heat transport and internal melting are predicted to be, or have been, widespread in the outer solar system. Convection, and the tectonics that result, would then only occur in ice I shells whose viscosities are lowered by tidal flexing, e.g., Europa (McKinnon, GRL 26, 951-954), Ganymede, or Triton. This analysis is, while correct, incomplete. At low stresses, where non-Newtonian viscosities can be arbitrarily large, convective instabilities may arise in the diffusional creep regime. Lattice diffusion creep has not been directly observed in water ice, but measurements of diffusion coefficients imply Newtonian viscosities low enough (for warm enough ice) that convection is expected above Callisto's internal liquid layer for plausible ice grain sizes (less than 5 mm). Convective heat flows will exceed steady-state radiogenic values unless the convective adiabat is cooler than the minimum melting temperature (251 K). In convective equilibrium, Callisto's stagnant lid is quite thick (about 100 km), and compatible with the lack of active geology, but the existence of the ocean requires an antifreeze.

McKinnon, W. B.

2001-11-01

257

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

258

Outer-shell excitation mechanisms and static-mode laser-fluorescence spectroscopy of sputtered atoms  

SciTech Connect

A review of the literature on atoms sputtered in electronically excited states is given together with a discussion of various mechanisms that have been proposed to account for the observations. The major observational features that have emerged from the older studies may be summarized as follows: (1) the kinetic energies of neutral atoms in highly excited electronic states are 1-2 orders of magnitude greater than E/sub b/, the surface binding energy; (2) relative yields show approximately exponential dependence on excitation energy with characteristic temperatures measured in thousands of degrees; (43) absolute yields are lower by 2-3 orders of magnitude than secondary ion yields which themselves are usually very small compared to total sputtering yields. In many cases, excited-state yields increase 1-2 orders of magnitude as a result of surface oxidation. 83 references.

Gruen, D.M.; Pellin, M.J.; Young, C.E.; Mendelsohn, M.H.; DeWald, A.B.

1982-01-01

259

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

NASA Technical Reports Server (NTRS)

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 kilometers 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 thickness 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.

Schenk, Paul M.

2002-01-01

260

Micropipette aspiration on the outer hair cell lateral wall.  

PubMed Central

The mechanical properties of the lateral wall of the guinea pig cochlear outer hair cell were studied using the micropipette aspiration technique. A fire-polished micropipette with an inner diameter of approximately 4 microm was brought into contact with the lateral wall and negative pressure was applied. The resulting deformation of the lateral wall was recorded on videotape and subjected to morphometric analysis. The relation between the length of the aspirated portion of the cell and aspiration pressure is characterized by the stiffness parameter, K(s) = 1.07 +/- 0.24 (SD) dyn/cm (n = 14). Values of K(s) do not correlate with the original cell length, which ranges from 29 to 74 microm. Theoretical analysis based on elastic shell theory applied to the experimental data yields an estimate of the effective elastic shear modulus, mu = 15.4 +/- 3.3 dyn/cm. These data were obtained at subcritical aspiration pressures, typically less than 10 cm H2O. After reaching a critical (vesiculation) pressure, the cytoplasmic membrane appeared to separate from the underlying structures, a vesicle with a length of 10-20 microm was formed, and the cytoplasmic membrane resealed. This vesiculation process was repeated until a cell-specific limit was reached and no more vesicles were formed. Over 20 vesicles were formed from the longest cells in the experiment. Images FIGURE 3 FIGURE 7

Sit, P S; Spector, A A; Lue, A J; Popel, A S; Brownell, W E

1997-01-01

261

The Shell Island Dilemma  

NSDL National Science Digital Library

The objective of this inquiry simulation is to investigate the issues concerning the fate of the Shell Island Resort, which is in danger of being destroyed by a migrating inlet, and then debate the future of this and other oceanfront structures threatened by coastal erosion. As students engage in their investigation, they are asked to identify the social, political, and scientific issues with which different stakeholders must deal. They will place themselves into the role of one of the stakeholders. The site lists the stakeholders and provides several sources of information for each. After reviewing the resources, students will prepare a statement to decide what should be the next course of action regarding the Shell Island Resort. Students then will present statements in a debate to decide the future of the resort.

262

Shoulder and hip joints for hard space suits and the like  

NASA Technical Reports Server (NTRS)

For use in hard space suits and the like, a joint between the torso covering and the upper arm covering (i.e., shoulder) or between the torso covering and upper leg covering (i.e., hip) is disclosed. Each joint has an outer covering and a inner covering. The outer covering has plural perferably truncated toroidal sections decreasing in size proceeding outwardly. In one embodiment at each joint there are two bearings, the first larger than the second. The outer race of the larger bearing is attached to the outer edge of the smaller end of each section and the inner race of the larger bearing is attached to the end wall. The inner race of the smaller bearing is attached to the end wall. The outer race of the smaller bearing is attached to the larger end of the next section. Each bearing hask appropriate seals. Between each section is a rubber ring for the comfort of the wearer. Such rubber rings have radial flanges attached to the inner races of two adjacent bearings. Matching semicircular grooves are formed in the abutting overlapping surfaces. Bellows-like inner walls are also provided for each section fixed at one end to an inner cylindrical flange and, at the opposite end, to an end wall. Each outer section may rotate 360 deg relative to the next outer section, whereas the bellows sections do not rotate, but rather expand or contract locally as the rigid sections rotate relative to each other.

Vykukal, H. C.

1986-01-01

263

Future exploration of the outer solar system  

NASA Astrophysics Data System (ADS)

Missions to the frigid outer reaches of our solar system present significant technological challenges, but there remains a breathtaking scope for new and exciting discoveries. Leigh Fletcher reports on an RAS meeting that demonstrated a host of innovative ideas to explore the giant planets.

Fletcher, Leigh

2013-04-01

264

Quasiperiodic Variations in The Outer Zone  

NASA Astrophysics Data System (ADS)

The temporal characteristics of energetic electron variation in the outer zone are examined using data detected on geosynchronous orbit and middle-earth orbit. The data detected of energetic electron over 2 solar activity cycle on geosynchronous orbit are analyzed, and the data detected on the middle-earth orbit over half a solar cycle are analyzed. Investigating the temporal characteristic of these data, we find that there are some quasiperiodic variations on variable timescales. On large timescale, the energetic electron fluxes in the outer zone are varying correlated with solar activity cycle obviously. The filter analysis in different frequency reveals that there is clear seasonal fluctuation in the outer zone, and 27-day quasiperiodic variation usually emerges in the approach to the solar minimum. Analyzing the seasonal fluctuation in detail, we find that the maximum fluxes of energetic electron occur near the equinoxes with some delay, and the minimum fluxes occur near the solstices. The seasonal fluctuation is correlated with the seasonal variation of efficiency of solar-terrestrial energy coupling. The investigation to the interplanetary conditions reveals that while the 27-day quasiperiodic variation of energetic electron in the outer zone emerges the solar wind speed and interplanetary magnetic field fluctuate in the similar period, and this kind of quasiperiodic variation is correlated with the long-lived coronal hole close to the solar equator.

Yang, Xiaochao; Zhu, Guangwu; Liang, Jinbao; Zhang, Xiaoxin; Wang, Chunqin; Jing, Tao

2014-05-01

265

Ground Based Studies of the Outer Planets  

NASA Technical Reports Server (NTRS)

This report covers progress to date under this grant on our continuing program to conduct ground based studies of the outer solar system planets and satellites, with emphasis on spectroscopy and atmospheric phenomena. The research continues under our new PAST grant, NNG04G131G beginning 5/1/2004. The original period of performance of the subject grant was 3/1/2001 to 2/28/2004, but was extended one year at no cost. Although there is some overlap in the scientific projects conducted during the extended year with those of the new grant, this report is confined to the portion of the work funded under NAG5-10435. The primary goals for this grant period were a comparative study of outer planet thermospheres/ionospheres near solar maximum, extended to the mid-IR, and the investigation of molecular dimers in outer solar system atmospheres. This project supports NASA's planned space missions, Jupiter Polar Orbiter, outer Planet Microprobes, and the recent Cassini flyby of Jupiter. It also supports the OSS strategic plan themes, The Exploration of the Solar System and The Sun-Earth Connection/ Understanding comparative planetary space environments.

Trafton, Laurence M.

2005-01-01

266

To the Outer Solar System and Beyond  

Microsoft Academic Search

The Space Age is nearly 50 years old but exploration of the outer planets and beyond has only just begun. Deep-Space Probes Second Edition draws on the latest research to explain why we should explore beyond the edge of the Solar System and how we can build highly sophisticated robot spacecraft to make the journey. Many technical problems remain to

Gregory L. Matloff

2005-01-01

267

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

268

The Exploration of Outer Space With Cameras  

Microsoft Academic Search

This monograph ``chronicles the use of television cameras and other visual imaging systems by NASA on unmanned outer space probes and in the exploration of the Solar System's planetary bodies.''The book is technically well organized and a nicely printed volume with the unfortunate exception of the 32 illustrative plates that are of nothing less than abysmal quality. Included in the

Michael J. S. Belton

1984-01-01

269

Structural basis for outer membrane lipopolysaccharide insertion.  

PubMed

Lipopolysaccharide (LPS) is essential for most Gram-negative bacteria and has crucial roles in protection of the bacteria from harsh environments and toxic compounds, including antibiotics. Seven LPS transport proteins (that is, LptA-LptG) form a trans-envelope protein complex responsible for the transport of LPS from the inner membrane to the outer membrane, the mechanism for which is poorly understood. Here we report the first crystal structure of the unique integral membrane LPS translocon LptD-LptE complex. LptD forms a novel 26-stranded ?-barrel, which is to our knowledge the largest ?-barrel reported so far. LptE adopts a roll-like structure located inside the barrel of LptD to form an unprecedented two-protein 'barrel and plug' architecture. The structure, molecular dynamics simulations and functional assays suggest that the hydrophilic O-antigen and the core oligosaccharide of the LPS may pass through the barrel and the lipid A of the LPS may be inserted into the outer leaflet of the outer membrane through a lateral opening between strands ?1 and ?26 of LptD. These findings not only help us to understand important aspects of bacterial outer membrane biogenesis, but also have significant potential for the development of novel drugs against multi-drug resistant pathogenic bacteria. PMID:24990744

Dong, Haohao; Xiang, Quanju; Gu, Yinghong; Wang, Zhongshan; Paterson, Neil G; Stansfeld, Phillip J; He, Chuan; Zhang, Yizheng; Wang, Wenjian; Dong, Changjiang

2014-07-01

270

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

271

The Outer Planets\\/Solar Probe Project  

Microsoft Academic Search

As part of NASA's Origins program, the Outer Planets\\/Solar Probe Project was established in early 1998. This flight project is composed of three challenging and exciting missions which span the far reaches of the solar system. Europa Orbiter, with a planned launch in November of 2003, will travel to Jupiter's moon, Europa, in search of a subsurface liquid water ocean

R. W. Maddock; K. B. Clark; C. A. Henry; P. J. Hoffman

1999-01-01

272

The Outer Planets: Getting There Fast  

NASA Technical Reports Server (NTRS)

In this paper, a brief review is given of NASA's outer planet missions as performed with chemical propulsion systems. The Kuiper Express is discussed as an illustration of the integrated approach that should be used in mission and spacecraft design to maximize science return.

Penzo, Paul A.

1996-01-01

273

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. ...

274

[Chemistry in Outer Solar System and Beyond  

NASA Technical Reports Server (NTRS)

During the three years of the NASA Planetary Atmospheres grant NAG51 1032, we have developed photochemical models for Jupiter, Saturn, Uranus, Neptune, Io, and extrasolar giant planets. We have compared the Io and outer planet model predictions with various infrared and microwave observations.

2004-01-01

275

Thermomechanical Postbuckling of Shells  

NASA Technical Reports Server (NTRS)

A number of issues involving the postbuckling of doubly-curved panels exposed to a non-uniform temperature field and subjected to a system of mechanical loads are considered in this paper. Effects played by transverse shear, initial geometric imperfections, membrane and thickness-wise temperature gradient, tangential edge constraints, linear/non-linear elastic foundation are incorporated and their implications on the non-linear response behavior of shells are discussed. Issues related with the delay of the occurrence of the snap-through buckling, alleviation of its intensity and even with its removal are addressed and remarks on conditions rendering a curved panel insensitive to initial geometric imperfections are included. Results on small vibration of shells about sub- and post-critical ranges are provided and structural modeling issues playing a non-negligible role towards a reliable prediction of the postbuckling behavior of shells under complex loading conditions are discussed. Results on non-linear response of flat reinforced panels subjected to thermomechanical loads are also presented. Finally, problems not covered by this article are briefly indicated.

Librescu, Liviu

1998-01-01

276

Detecting the Rapidly Expanding out Shell of the Crab Nebula: Where to Look  

NASA Astrophysics Data System (ADS)

We present a range of steady-state photoionization simulations, corresponding to different assumed shell geometries and compositions, of the unseen postulated rapidly expanding outer shell to the Crab Nebula. The properties of the shell are constrained by the mass that must lie within it, and by limits to the intensities of hydrogen recombination lines. In all cases the photoionization models predict that the NIR [Ne VI] ?7.65 ?m line should be the strongest line emitted by the shell. This line is predicted to be dramatically brighter than the optical lines commonly used in searches. The C IV ?1549Å doublet is predicted to be the strongest absorption line from the shell, which is in agreement with HST observations. However we show that the cooling timescale for the fast shell is much longer than the age of the Crab, due to the low density. This means that the temperature of the shell will actually “remember” its initial conditions. The recombination time is much shorter than the age of the Crab, so the predicted level of ionization should approximate the real ionization. In any case, it is clear that IR observations present the best opportunity to detect the fast shell and so guide future models that will constrain early events in the original explosion.

Wang, Xiang; Ferland, G. J.; Baldwin, J. A.; Loh, E. D.; Richardson, C. T.

2013-06-01

277

Drift shells and aurora computed using the O8 magnetic field model for Neptune  

NASA Technical Reports Server (NTRS)

Charged particle drift shells are calculated using the O8 magnetic field model for Neptune. Inner drift shell morphologies differ significantly from dipolar drift shells for the parts of drift shells inward of r = 2 R(sub N). Outer drift shells (L approx. greater than 10), when traced down to Neptune's surface following magnetic field lines, are simple closed loops around magnetic poles. Inner drift shells (L approx. less than 4), on the other hand, when traced to the surface, are also single loops but stretched in a previously unknown way: sometimes with a cusp and sometimes into two joined loops. Inner drift shell footprints on R = 1 provide the basis for identifying precipitation L shells, interpreting observed aurora, and predicting additional emissions on that part of Neptune's surface unobserved by the Ultraviolet Spectrometer (UVS). Precipitation in a global magnetic anomaly, `ordinary' auroral precipitation near the south magnetic pole, and precipitation from field lines with no magnetic field minimum above Neptune's exobase collectively appear to account for all of the observed auroral emission regions at Neptune. To the extent that aurora can be understood in this model, it is suggested O8 may be reasonably accurate.

Paranicas, C.; Cheng, A. F.

1994-01-01

278

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

279

STP Hard Disks MD Program  

NSDL National Science Digital Library

The STP Hard Disks MD program simulates the dynamics of a system of hard disks. The default parameters are N=64 particles in a box of length L = 18.0 and a temperature T=1.0. The particles are initially in a regular array. STP HardDisksMD is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double-clicking the stp_HardDisksMD.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2009-03-06

280

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

281

Confined Hard Disk System Model  

NSDL National Science Digital Library

The Confined Hard Disk System is an idealized statistical mechanics model that simulates a two-dimensional system of hard disks confined to a box with a constant temperature thermal reservoir at one end and a movable piston at the other. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. The model computes and plots the time evolution of the kinetic energy K per particle, the pressure P, and the volume V. The model also displays histograms and mean values of these quantities. The Confined Hard Disk System was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_hd_ConfinedHardDiskSystem.jar file will run the program if Java is installed.

Christian, Wolfgang

2010-12-27

282

Ejs Hard Disk Gas Model  

NSDL National Science Digital Library

The Ejs Hard Disk Gas model displays a two-dimensional gas made out of hard disks. Particles are initialized with a speed v=1 in a random direction and move with constant velocity until a collision occurs. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Hard Disk Gas model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_newton_HardDiskGas.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for statistical mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-07-06

283

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

284

QPX Disease in Hard Clams  

NSDL National Science Digital Library

This New York SeaGrant PDF-brochure examines QPX (Quahog Parasite Unknown, a disease-causing parasite) as it relates to the hard clam fishery in New York. It discusses the origin of QPX, how it infects hard clams, where it has been found, signs of QPX disease, why people in New York should be concerned, and what is being done to control its spread.

Barnes, Debra; Allam, Bassem; Gall, Ken; Seagrant, New Y.

285

Microstructural design of hard coatings  

Microsoft Academic Search

Microstructural design has attracted increasing interest in modern development of hard coatings for wear-resistant applications. In plasma-assisted vapor deposited thin films, the material’s microstructure can be designed during growth or post-deposition annealing treatments. In this review, we demonstrate the correlation between microstructure and mechanical as well as tribological properties of hard ceramic coatings. This is done for single-phase coatings and

Paul H. Mayrhofer; Christian Mitterer; Lars Hultman; Helmut Clemens

2006-01-01

286

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

287

Myxobacteria produce outer membrane-enclosed tubes in unstructured environments.  

PubMed

Myxobacteria are social microbes that exhibit complex multicellular behaviors. By use of fluorescent reporters, we show that Myxococcus xanthus isolates produce long narrow filaments that are enclosed by the outer membrane (OM) and contain proteins. We show that these OM tube (OMT) structures are produced at surprisingly high levels when cells are placed in liquid medium or buffer without agitation. OMTs can be long and easily exceed multiple cell lengths. When viewed by transmission electron microscopy, their morphology varies between tubes and chain-like structures. Intermediate-like structures are also found, suggesting that OMTs may transition between these two morphotypes. In support of this, video epifluorescence microscopy found that OMTs in solution dynamically twist and jiggle. On hard surfaces, myxobacteria glide, and upon cell-cell contact, they can efficiently exchange their OM proteins and lipids by a TraAB-dependent mechanism. Although the structure of OMTs hints at a possible role as conduits for exchange, evidence is presented to the contrary. For example, abundant OMT production occurs in traA or traB mutants and when cells are grown in liquid medium, yet transfer cannot occur under these conditions. Thus, genetic and environmental conditions that promote OMT production are incongruent with OM exchange. PMID:24391054

Wei, Xueming; Vassallo, Christopher N; Pathak, Darshankumar T; Wall, Daniel

2014-05-01

288

76 FR 63654 - Outer Continental Shelf Official Protraction Diagram, Lease Maps, and Supplemental Official Outer...  

Federal Register 2010, 2011, 2012, 2013

...Shelf Official Protraction Diagram, Lease Maps, and Supplemental Official Outer Continental...Official Protraction Diagram (OPD), Lease Maps, and Supplemental Official OCS Block Diagrams...OCS Official Protraction Diagram, Lease Maps, and Supplemental Official OCS Shelf...

2011-10-13

289

Pyrolysis characteristics and global kinetics of coconut and cashew nut shells  

Microsoft Academic Search

Coconut and cashew nut shells are two typical biomass wastes abundant in most of the tropical countries. However, despite their enormous potential as energy sources, they are hardly studied and their thermal characteristics are still not well known. In this study, both biomasses are thermally degraded through thermogravimetry and their characteristics such as devolatilisation profiles and kinetics are analyzed, from

Alberto J. Tsamba; Weihong Yang; Wlodzimierz Blasiak

2006-01-01

290

Resorcinol/formaldehyde foam shell targets for ICF  

SciTech Connect

Resorcinol/formaldehyde (R/F) low-density foam making processes have been adapted to microencapsulation techniques. This has been done in an effort to make low density, low Z, transparent foam shells for use as cryogenic ICF targets. It was necessary to modify the normal R/F formulation and processing to accelerate the gelation time from tens of hours to less than one hour. Proper selection of the inner and outer oil phase solvents was critical for density matching and prevention of the dehydration of the gelling preform, respectively. 12 refs., 5 figs., 1 tab.

Overturf, G.E. III.; Cook, R.; Letts, S.A.; Buckley, S.R. [Lawrence Livermore National Lab., CA (United States); McClellan, M.R.; Schroen-Carey, D. [W. J. Schafer and Associates, Livermore, CA (United States)

1995-12-01

291

Abundance Measurements in the Outer Galaxy  

NASA Astrophysics Data System (ADS)

We have observed far-infrared fine structure lines of N, O, and S in five H II regions in the far outer Galaxy (R > 15 kpc) using the Kuiper Airborne Observatory (KAO). These sources were selected from a radio continuum search we made with the VLA and Australia Telescope Compact Array. The far-infrared line observations, combined with the radio continuum fluxes from these regions, allow us to determine the abundances relative to hydrogen of these three elements in an extreme part of the Galaxy. These observations have extended, by almost a factor of 2, the range of galactocentric radius (R) over which abundances have been determined using this technique. Earlier studies of abundances in the Milky Way have indicated that there is a gradient in heavy element abundances between the Galactic center and the Solar circle, but the distribution in the outer Galaxy has been less certain (Shaver et al. 1983, MNRAS, 204, 53; Fich & Silkey 1991, ApJ, 366, 107); Simpson et al. 1995, ApJ, submitted), with one study indicating that the N abundance flattens out beyond the Solar circle (Fich & Silkey 1991). Our results seem to contradict this finding. Our abundance measurements are consistent with those found by Fich and Silkey for individual outer Galaxy HII regions. However, when they are combined with measurements made of inner Galaxy H II regions using the identical instruments and analysis techniques, our data suggest that the abundances in all three elements, N, O, and S, continue to fall in the outer Galaxy. For example, our results indicate that the abundance of N is 2--3 times lower in the outer Galaxy than at the Solar neighborhood, and is 10 times lower than in the inner Galaxy. This result, in addition to having important implications for models of Galactic chemical structure and evolution (see, e.g., Wilson and Matteucci 1992, A&AR, 4, 1), also confirms that the outer Galaxy is an ideal place to study a region of star-formation very different from the Solar neighborhood, but, unlike in other galaxies, close enough to allow detailed studies of individual star-forming regions.

Rudolph, Alexander L.; Simpson, Janet P.; Erickson, Edwin F.; Haas, Michael R.; Fich, Michel

1994-12-01

292

Current status of ASTRO-H Hard X-ray Telescopes (HXTs)  

NASA Astrophysics Data System (ADS)

ASTRO-H is an international X-ray mission of ISAS/JAXA, which will be launched in 2014. One of the main characteristics of ASTRO-H is imaging spectroscopy in the hard X-ray band above 10 keV. ASTRO-H will carry two identical Hard X-ray telescopes (HXTs), whose mirror surfaces are coated with Pt/C depth-graded multilayers to enhance hard X-ray effective area up to 80 keV. HXT was designed based on the telescope on board the SUMIT balloon borne experiment. After feasibility study of the HXT design, the FM design has been deteremined. Mass production of the mirror shells at Nagoya University has been going on since August 2010, and production of mirror shells for HXT-1 was completed in March 2012. After the integation of X-ray mirrors for HXT-1, we measured hard X-ray performance of selected mirror shells for HXT-1 at a synchrotron radiation facility, SPring-8 beamline BL20B2. We will perform environment tests and ground calibarations at SPring-8 for HXT-1. In HXT-2, foil production is going on.

Awaki, Hisamitsu; Kunieda, Hideyo; Furuzawa, Akihiro; Haba, Yoshito; Hayashi, Takayuki; Iizuka, Ryo; Ishibashi, Kazunori; Ishida, Manabu; Itoh, Masayuki; Kosaka, Tatsuro; Maeda, Yoshitomo; Matsumoto, Hironori; Miyazawa, Takuya; Mori, Hideyuki; Nagano, Hosei; Namba, Yoshiharu; Ogasaka, Yasushi; Ogi, Keiji; Okajima, Takashi; Sugita, Satoshi; Suzuki, Yoshio; Tamura, Keisuke; Tawara, Yuzuru; Uesugi, Kentaro; Yamashita, Koujun; Yamauchi, Shigeo

2012-09-01

293

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

294

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

2013-01-01

295

Wave observations in outer planet magnetospheres  

NASA Technical Reports Server (NTRS)

The first measurements of plasma waves and wave-particle interactions in the magnetospheres of the outer planets were provided by instruments on Voyager 1 and 2. At Jupiter, the observations yielded new information on upstream electrons and ions, bow shock dissipation processes, trapped radio waves in the magnetospheres and extended Jovian magnetotail, pitch angle diffusion mechanisms and whistlers from atmospheric lightning. Many of these same emissions were detected at Saturn. In addition, the Voyager plasma wave instruments detected dust particles associated with the tenuous outer rings of Saturn as they impacted the spacecraft. Most of the plasma wave activity at Jupiter and Saturn is in the audio range, and recordings of the wave observations have been useful for analysis.

Scarf, F. L.

1985-01-01

296

Distant asteroids and outer Jovian satellites  

NASA Technical Reports Server (NTRS)

Sixty percent of the sampled objects in the Hilda, Trojan and outer Jovian satellite locations belong to C-type and another 30% belong to a new group called RD-type (reddish and dark), sometimes referred to simply as D-type. Objects in this group have low albedo values between 2 and 4% and steep reflection spectra between 0.7 micron and 0.9 micron. Furthermore, 944 Hidalgo belongs to this group but shows color variation over its surface. Meteoritic minerals with similar optical reflection spectra are discussed. Trojans with sizes down to 15 km in the cloud preceding Jupiter are about 3.5 times more numerous than those in the following cloud. RD-type Trojans appear more often in the preceding cloud. There is a resemblance of spectrum, albedo and phase relation among the majority of Trojans and the outer Jovian satellites.

Degewij, J.; Van Houten, C. J.

1979-01-01

297

Performance of the LHCb Outer Tracker  

NASA Astrophysics Data System (ADS)

The LHCb Outer Tracker is a gaseous detector covering an area of 5 × 6 m2 with 12 double layers of straw tubes. The detector with its services are described together with the commissioning and calibration procedures. Based on data of the first LHC running period from 2010 to 2012, the performance of the readout electronics and the single hit resolution and efficiency are presented. The efficiency to detect a hit in the central half of the straw is estimated to be 99.2%, and the position resolution is determined to be approximately 200 ?m. The Outer Tracker received a dose in the hottest region corresponding to 0.12 C/cm, and no signs of gain deterioration or other ageing effects are observed.

2014-01-01

298

Origins of outer-planet satellites  

NASA Technical Reports Server (NTRS)

Aspects of satellite origin and evolution which bear on the formation of the solar system are addressed, with emphasis on the chemical evidence contained in satellites concerning the modification of the interstellar material which went to form the solar system. New results on the tidal evolution of outer-planet satellite systems are presented. The gross physical and chemical properties of the satellite systems of the outer planets are outlined. Models for regular satellite formation are reviewed. Attention is given to the evolution of the satellites, with emphasis on tidal evolution, including a discussion of the dynamical origin of Triton. The volatile budgets of Titan, Triton, and Pluto/Charon are discussed, and models are presented for the origin of these budgets which tie them to the larger set of processes associated with solar system formation.

Lunine, Jonathan I.; Tittemore, William C.

1993-01-01

299

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

300

Fluxgate magnetometers for outer planets exploration  

NASA Technical Reports Server (NTRS)

The exploration of the interplanetary medium and the magnetospheres of the outer planets requires the implementation of magnetic field measuring instrumentation with wide dynamic range, high stability, and reliability. The fluxgate magnetometers developed for the Pioneer 11 and Mariner-Jupiter-Saturn missions are presented. These instruments cover the range of .01 nT to 2 million nT with optimum performance characteristics and low power consumption.

Acuna, M. H.

1974-01-01

301

New fatty acids from outer space  

Microsoft Academic Search

A recent space exploration has revealed that in the far reaches of outer space matter attains a state of complete weightlessness.\\u000a Herman Brown, reporting on his latest spaced-out venture, indicates that weightless fatty acids obtained from the Superba\\u000a Galaxy are ideally suited for the manufacture of improved food additives. What a magnificent way to provide the diet-control\\u000a foodstuffs of the

H. Brown

1979-01-01

302

Fluxgate magnetometers for outer planets exploration  

Microsoft Academic Search

The exploration of the interplanetary medium and the magnetospheres of the outer planets requires the implementation of magnetic field measuring instrumentation with wide dynamic range, high stability, and reliability. The fluxgate magnetometers developed for the Pioneer 11 and Mariner-Jupiter-Saturn missions are presented. These instruments cover the range of .01 nT to2 times 10^{6}nT with optimum performance characteristics and low power

M. Acuna

1974-01-01

303

Ion anisotropies in the outer Jovian magnetosphere  

Microsoft Academic Search

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

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

1981-01-01

304

Cosmic ray gradients in the outer heliosphere  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

305

Involute, minimal, outer, and increasingly trapped spheres  

NASA Astrophysics Data System (ADS)

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-Nordström 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.

2010-01-01

306

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

307

7 CFR 51.2002 - Split shell.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Split shell. 51.2002 Section 51.2002 Agriculture...States Standards for Grades of Filberts in the Shell 1 Definitions § 51.2002 Split shell. Split shell means a shell having...

2009-01-01

308

7 CFR 51.2002 - Split shell.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Split shell. 51.2002 Section 51.2002 Agriculture...States Standards for Grades of Filberts in the Shell 1 Definitions § 51.2002 Split shell. Split shell means a shell having...

2010-01-01

309

Outer ear temperature and time of death.  

PubMed

From a research sample of 138 corpses, divided into four subgroups of ambient storage temperature (0-5 degrees C, 6-10 degrees C, 11-15 degrees C and 16-23 degrees C) four linear regression formulae of actual versus estimated post-mortem interval were obtained ('interval' formulae) using a single outer ear temperature measurement on both sides. This method showed the best correlation coefficient among five other methods previously proposed for time of death determination (rectal temperature, vitreous K+, CSF K+, blood log NA+/K+ and log Cl-), however its results were less accurate than those obtained with a multivariate equation combining several of the above mentioned methods. Eventually an equation expressing time of death (TOD) as a function of outer ear temperature (OE T degrees) and ambient temperature was also established from the whole research sample ('global' formulae). On a different sample of 141 corpses the regression formulae ('interval' and 'global') for the outer ear temperature were compared to three methods based on a single rectal temperature measurement ('rule of thumb' 1 and 2, Henssge nomogram) and therefore useful at the scene; the results of all methods were compared within the four subgroups of ambient temperature as well as in three subgroups of different post-mortem interval lengths (< 7 h, < 10 h, < 15 h). In all cases the outer ear temperature formulae provided better results than the rectal temperature methods (especially Henssge nomogram and rule of thumb 1). Moreover they did not show any post-mortem plateau which was present in almost 30% of cases when rectal temperature was measured in corpses kept at ambient temperature above 15 degrees C. Our results show that outer ear temperature measurement is the method which provides the best simplicity/quality ratio and should therefore be proposed for use at the scene when conditions are similar to those of our experiment (within buildings). A software equipped thermometer is required in order to use in each case the appropriate formula and confidence interval. PMID:9022275

Baccino, E; De Saint Martin, L; Schuliar, Y; Guilloteau, P; Le Rhun, M; Morin, J F; Leglise, D; Amice, J

1996-12-01

310

Biomineralisation in Mollusc shells  

NASA Astrophysics Data System (ADS)

The main components of Mollusc shells are carbonate minerals: calcite and aragonite. ACC is present in larval stages. Calcite and aragonite can be secreted simultaneously by the mantle. Despite the small number of varieties, the arrangement of the mineral components is diverse, and dependant upon the taxonomy. They are also associated with organic components much more diverse, the diversity of which reflects the large taxonomic diversity. From TGA analyses, the organic content (water included) is high (>5% in some layers). The biomineralisation process is not a passive precipitation process, but is strongly controlled by the organism. The biological-genetic control is shown by the constancy of the arrangement of the layers, the mineralogy and the microstructure in a given species. Microstructural units (i.e. tablets, prisms etc.) have shapes that do not occur in non-biogenic counterparts. Nacreous tablets, for example, are flattened on their crystallographic c axis, which is normally the axis of maximum growth rate for non-biogenic aragonite. Morever, their inner structure is species-specific: the arrangements of nacreous tablets in Gastropoda - Cephalopoda, and in Bivalvia differ, and the inner arrangement of the nacreous tablets is different in ectocochlear and endocochlear Cephalopoda. The organic-mineral ratios also differ in the various layers of a shell. Differences in chemical composition also demonstrates the biological-genetic control: for example, aragonite has a low Sr content unknown in non-biogenic samples; two aragonitic layers in a shell have different Sr and Mg contents, S is higher in calcitic layers. Decalcification releases soluble (SOM) and insoluble (IOM) organic components. Insoluble components form the main part of the intercrystalline membranes, and contain proteins, polysaccharides and lipids. Soluble phases are present within the crystals and the intercrystalline membranes. These phases are composed of more or less glycosylated proteins and polysaccharides, with a large range of molecular weights. Proteins are rich in acidic aminoacids (aspartic and glutamic acids). Sugars are usually sulphated, and very acidic. Several hundreds of proteins and sugars are present in the SOM. The compositions of IOM and SOM are characteristic for each layer present in a shell. Topographical relationships of mineral and organic components are visible at different scales of observation. SEM images of etched surfaces display the growth line rhythmicity and concordance between adjacent microstructural units. EPMA maps show similar chemical growth lines in various structures. Whatever the taxa, the average thickness of growth lines is about 2-3 µm, indicating an inner biological rhythm, not dependant on the environmental conditions. Such growth lines are observed in deep sea molluscs at depth where diurnal changes in light and temperature are absent. However, the role of the environment is shown by larger periodicities. Sulphur deserves a special interest, because it is associated with the organic matrices. Electrophoretic data have shown that acidic sulphated sugars are abundant in some layers. XANES analyses confirm these results. New microscopic techniques allow us to obtain images at a submicrometer scale. AFM images show that all the microstructural units (i.e. tablets, prisms etc.), calcite or aragonite, are composed of small sub-spherical granules with a diameter typically of about 50 nm. These granules are surrounded by a thin cortex (about 8 nm) of organic and/or amorphous material, and are organo-composite material as shown by phase images. They do not have crystalline shapes, despite the fact that the units they build are often monocrystalline. Molecular biology and genetic studies confirm that the control of the biomineralisation process is exerted at the scale of the whole organism: the expression of genes encoding major shell matrix proteins clearly indicates a regular separation of calcite and aragonite secretory activity. The main control on the structural and compositional features of mollusc she

Dauphin, Y.; Cuif, J. P.; Salomé, M.; Williams, C. T.

2009-04-01

311

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

312

Discovery of Molecular Gas Shells around the Unusual Galaxy Centaurus A  

NASA Astrophysics Data System (ADS)

Recent observations by an international team of astronomers [1] with the 15-metre Swedish-ESO Submillimetre Telescope at the La Silla observatory (Chile) have shown that the unusual, nearby galaxy Centaurus A is surrounded by shells in which carbon monoxide molecules are present. These new exciting results are the first of their kind. In addition to the intrinsic scientific value of this discovery, it also provides an instructive example of what will become possible for more distant galaxies with the projected Atacama Large Millimeter Array (ALMA) , now in the planning phase. Ellipticals and spirals Galaxies come in different shapes. Some of these take the form of more or less perfect spirals, some have the form of ellipsoids and still others have an irregular appearance. One of the major differences between elliptical and spiral galaxies is that the former do not possess extensive gaseous discs in which young stars can be formed. This is despite the fact that most elliptical galaxies are probably formed by the merger of two or more spiral galaxies. However, during such a process most of the gas in the spirals is either quickly turned into stars by massive bursts of star formation or is completely lost into the surrounding space. Shells around elliptical galaxies Most galaxies are members of groups. Once they have been formed, massive elliptical galaxies in these often behave like "cannibals" by swallowing one or more smaller companion galaxies. Some vestiges of such an event may remain visible for a certain time after the merger, normally in the form of weak structures in the otherwise smooth light distribution over the elliptical galaxy. These structures resemble the ripples or waves that develop on the water surface when you throw a small stone into a calm pond. While long-exposure photos show them as faint "rings" around the galaxy, they are in fact the projected images of three-dimensional structures and are often referred to as shells . By means of photometric and spectrographic studies of their light, it has been known since the early 1980's that such shells are made up of stars. It appears that they are quite common - about half of the nearby large elliptical galaxies have been found to be surrounded by stellar shells. More recently, in 1994, atomic hydrogen gas was discovered to be associated with some of the stellar shells. This discovery was a bit of a surprise, because the current theory predicts that when two galaxies merge, their gas and stars will behave very differently. While the individual stars hardly ever hit each other, the interstellar gas clouds collide violently. They will lose all their energy and the gas will fall towards the common centre where it is soon consumed in vigorous bursts of star formation. Why would there then be hydrogen gas in the outer shells of some elliptical galaxies? A possible origin of gaseous shells The astronomer team, headed by Vassilis Charmandaris [1] decided to look into this serious discrepancy between theory and observations. They believed that a possible explanation might be that this diffuse atomic gas is located, not in vast, very dilute clouds, but rather in smaller, much denser molecular clouds , such as these are known in our own galaxy, the Milky Way. Due to their relative compactness (more than 1000 molecules/cm 3 , i.e,. at least 100 times more than that of larger diffuse clouds), molecular clouds would behave more like the stars during the galaxy collision event. Indeed, realistic calculations showed that the dynamical behavior of such dense clouds would be intermediate between the stars and the diffuse hydrogen gas. Thus, while most of the gas would still end up in the centre of the remaining galaxy after a merger, a larger fraction of it would be able to survive at large distances from the nucleus. This would then be the origin of the observed hydrogen shells. During the merger, gas that originates from regions in the outskirts of the "cannibalized" galaxy - and farther out than most of the stars - would be liberated earlier

2000-03-01

313

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

2013-02-01

314

Fast ignition upon the implosion of a thin shell onto a precompressed deuterium-tritium ball  

NASA Astrophysics Data System (ADS)

Fast ignition of a precompressed inertial confinement fusion (ICF) target by a hydrodynamic material flux is investigated. A model system of hydrodynamic objects consisting of a central deuterium-tritium (DT) ball and a concentric two-layer shell separated by a vacuum gap is analyzed. The outer layer of the shell is an ablator, while the inner layer consists of DT ice. The igniting hydrodynamic flux forms as a result of laser-driven acceleration and compression of the shell toward the system center. A series of one-dimensional numerical simulations of the shell implosion, the collision of the shell with the DT ball, and the generation and propagation of thermonuclear burn waves in both parts of the system are performed. Analytic models are developed that describe the implosion of a thin shell onto a central homogeneous ball of arbitrary radius and density and the initiation and propagation of a thermonuclear burn wave induced by such an implosion. Application of the solution of a model problem to analyzing the implosion of a segment of a spherical shell in a conical channel indicates the possibility of fast ignition of a spherical ICF target from a conical target driven by a laser pulse with an energy of 500-700 kJ.

Gus'kov, S. Yu.; Zmitrenko, N. V.

2012-11-01

315

Thermally induced phase transition of glucose-sensitive core-shell microgels.  

PubMed

Four series of poly(N-isopropylacrylamide) (PNIPAM) (core)/poly(N-isopropylacrylamide-co-3-acrylamidophenylboronic acid) (P(NIPAM-AAPBA)) (shell) microgels were synthesized by the modification of PNIPAM (core)/poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-AA)) (shell) microgels with 3-aminophenylboronic acid (APBA). Their thermosensitive behaviors were studied by dynamic light scattering. Two or three phase transitions were detected depending on the shell thickness. These transitions were confirmed by the first derivative plot of the turbidity data. The first transition occurring at about 17 degrees C was assigned to that of the P(NIPAM-AAPBA) shell, whereas the second and third ones, which occur at about 22 and 28 degrees C, respectively, were assigned to that of the PNIPAM core. These results indicate that the influences of a shrunk P(NIPAM-AAPBA) shell on the different parts of the PNIPAM core are different. As the outer part, or the "shell" part of the PNIPAM core, directly connects with the P(NIPAM-AAPBA) shell, its phase transition temperature is reduced to a larger degree as compared with that of the inner part, or the "core" part. Glucose-induced swelling was observed for all the microgels, indicating their glucose-sensitivity. However, the degree of glucose-induced swelling is much smaller than that of the pure P(NIPAM-AAPBA) microgels. PMID:20356278

Luo, Qiaofang; Liu, Pengxiao; Guan, Ying; Zhang, Yongjun

2010-03-01

316

Atomic Inner-Shell Processes.  

National Technical Information Service (NTIS)

X-Ray and Auger transition probabilities were calculated for atoms that have been singly and multiply ionized in inner shells. The effects of relativity and configuration interaction on these rates were studied, and lifetimes of atomic inner-shell holes w...

B. Crasemann M. H. Chen

1981-01-01

317

Foam shell cryogenic ICF target  

SciTech Connect

A uniform cryogenic layer of DT fuel is maintained in a fusion target having a low density, small pore size, low Z rigid foam shell saturated with liquid DT fuel. Capillary action prevents gravitational slumping of the fuel layer. The saturated shell may be cooled to produce a solid fuel layer.

Darling, Dale H. (Pleasanton, CA)

1987-01-01

318

Prevelance and Distribution of QPX, Quahog Parasite Unknown, in Hard Clams Mercenaria Mercenaria in Virginia, USA  

NSDL National Science Digital Library

This Diseases of Aquatic Organisms abstract serves as the first documentation of QPX (Quahog Parasite Unknown, a parasite affecting hard shell clams) in the state of Virginia. It reports findings from a sampling program performed in 1996 and 1997 that showed light to moderate parasite intensity ranging from 4% to 48% of each sampling period. At the time this article was published, QPX had not had a significant impact on Virginia's hard clam fishery and aquaculture industry, but the authors recommend continued monitoring and research.

Burreson, Eugene M.; Ragone Calvo, Lisa M.; Walker, Juanita G.

2009-07-14

319

Hardness of ion implanted ceramics  

SciTech Connect

It has been established that the wear behavior of ceramic materials can be modified through ion implantation. Studies have been done to characterize the effect of implantation on the structure and composition of ceramic surfaces. To understand how these changes affect the wear properties of the ceramic, other mechanical properties must be measured. To accomplish this, a commercially available ultra low load hardness tester has been used to characterize Al/sub 2/O/sub 3/ with different implanted species and doses. The hardness of the base material is compared with the highly damaged crystalline state as well as the amorphous material.

Oliver, W.C.; McHargue, C.J.; Farlow, G.C.; White, C.W.

1985-01-01

320

Optimal Design of Nonlinear Shell Structures.  

National Technical Information Service (NTIS)

A numerical method for optimal design of nonlinear shell structures is described. The nonlinearity is only geometrical and the external load is assumed to be conservative. The nonlinear shell is analyzed using standard shell finite elements with the displ...

U. T. Ringertz

1991-01-01

321

33 CFR 117.323 - Outer Clam Bay  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Outer Clam Bay 117.323 Section 117.323 Navigation...Specific Requirements Florida § 117.323 Outer Clam Bay The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on...

2009-07-01

322

33 CFR 117.323 - Outer Clam Bay  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Outer Clam Bay 117.323 Section 117.323 Navigation...Specific Requirements Florida § 117.323 Outer Clam Bay The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on...

2010-07-01

323

33 CFR 117.323 - Outer Clam Bay.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Outer Clam Bay. 117.323 Section 117.323 Navigation...Specific Requirements Florida § 117.323 Outer Clam Bay. The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on...

2013-07-01

324

Shell forming system  

NASA Technical Reports Server (NTRS)

An apparatus is provided for forming gas-filled spheres of metal, glass or other material, which produces spheres (12) of uniform size and wall thickness in a relatively simple system. The system includes concentric nozzles, including an inner nozzle (18) through which gas flows and and an outer nozzle (20), which jointly define an annular passageway (50) through which a liquid flows. The flow rates are adjusted so that the gas flows at greater velocity than does the liquid, out of their respective nozzles, e.g. three times as great, in order to produce an extrusion (30) which undergoes axisymmetric oscillations resulting in the pinch off into hollow spheres with very uniform spacing. The system is useful not only where gas-filled spheres are required, but also is useful to accurately control the dispensing of solid, liquid, or gaseous materials.

Kendall, Jr., James M. (Inventor); Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor)

1987-01-01

325

Shell tile thermal protection system  

NASA Technical Reports Server (NTRS)

A reusable, externally applied thermal protection system for use on aerospace vehicles subject to high thermal and mechanical stresses utilizes a shell tile structure which effectively separates its primary functions as an insulator and load absorber. The tile consists of structurally strong upper and lower metallic shells manufactured from materials meeting the thermal and structural requirements incident to tile placement on the spacecraft. A lightweight, high temperature package of insulation is utilized in the upper shell while a lightweight, low temperature insulation is utilized in the lower shell. Assembly of the tile which is facilitated by a self-locking mechanism, may occur subsequent to installation of the lower shell on the spacecraft structural skin.

Macconochie, I. O.; Lawson, A. G.; Kelly, H. N. (inventors)

1984-01-01

326

Influence of algal and suspended sediment concentrations on the feeding physiology of the hard clam Mercenaria mercenaria  

Microsoft Academic Search

Short-term laboratory feeding experiments were conducted to determine the response of the hard clam Mercenaria mercenaria (L.) (32 mm in mean shell length) to increasing sediment concentrations. Clams were fed mixed suspensions of Pseudoisochrysis paradoxa (50 and 150 cells µl-1) and bottom sediments (0 to 44 mg l-1). Algal ingestion rate deelined with increasing sediment loads. This resulted primarily from

V. M. Bricelj; R. E. Malouf

1984-01-01

327

A new simple analytical expression for the average site–site radial distribution function of hard sphere chain fluid  

Microsoft Academic Search

A new simple analytical expression for the first coordination shell (1?x?2) of the average site–site intermolecular radial distribution function (ASSIRDF) of freely jointed tangent hard sphere chain fluid (FJTHSC) is proposed. The proposed expression is a polynomial expansion of packing fraction. The dependence of each polynomial coefficient on the radial coordinate and segment number is described by a polynomial expansion

H. Farrokhpour; M. Sohrabi Mahboub

2011-01-01

328

Lunar and Planetary Science XXXV: Outer Solar System  

NASA Technical Reports Server (NTRS)

The session 'Outer Solar System" inlcuded:Monte Carlo Modeling of [O I] 630 nm Auroral Emission on Io; The Detection of Iron Sulfide on Io; Io and Loki in 2003 as Seen from the Infrared Telescope Facility Using Mutual Satellite and Jupiter Occultations; Mapping of the Zamama-Thor Region of Io; First Solar System Results of the Spitzer Space Telescope; Mapping the Surface of Pluto with the Hubble Space Telescope; Experimental Study on Fischer-Tropsch Catalysis in the Circum-Saturnian Subnebula; New High-Pressure Phases of Ammonia Dihydrate; Gas Hydrate Stability at Low Temperatures and High Pressures with Applications to Mars and Europa; Laboratory UV Photolysis of Planetary Ice Analogs Containing H2O + CO2 (1:1); The OH Stretch Infrared Band of Water Ice and Its Temperature and Radiation Dependence; Band Position Variations in Reflectance Spectra of the Jovian Satellite Ganymede; Comparison of Porosity and Radar Models for Europa s Near Surface; Combined Effects of Diurnal and Nonsynchronous Surface Stresses on Europa; Europa s Northern Trailing Hemisphere: Lineament Stratigraphic Framework; Europa at the Highest Resolution: Implications for Surface Processes and Landing Sites; Comparison of Methods to Determine Furrow System Centers on Ganymede and Callisto; Resurfacing of Ganymede by Liquid-Water Volcanism; Layered Ejecta Craters on Ganymede: Comparisons with Martian Analogs; Evaluation of the Possible Presence of CO2-Clathrates in Europa s Icy Shell or Seafloor; Geosciences at Jupiter s Icy Moons: The Midas Touch; Planetary Remote Sensing Science Enabled by MIDAS (Multiple Instrument Distributed Aperture Sensor); and In Situ Surveying of Saturn s Rings.

2004-01-01

329

Dynamic indentation hardness of materials  

NASA Astrophysics Data System (ADS)

Indentation hardness is one of the simplest and most commonly used measures for quickly characterizing material response under static loads. Hardness may mean resistance to cutting to a machinist, resistance to wear to a tribologist, or a measure of flow stress to a design engineer. In this simple technique, a predetermined force is applied to an indenter for 5-30 seconds causing it to penetrate a specimen. By measuring the load and the indentation size, a hardness value is determined. However, the rate of deformation during indenter penetration is of the order of 10sp{-4}\\ ssp{-1}. In most practical applications, such as high speed machining or impact, material deforms at strain rates in excess of 10sp3{-}10sp5\\ ssp{-1}. At such high rates, it is well established that the plastic behavior of materials is considerably different from their static counterpart. For example, materials exhibit an increase in their yield stress, flow stress, fracture stress, and fracture toughness at high strain rates. Hence, the use of static hardness as an indicator of material response under dynamic loads may not be appropriate. Accordingly, a simple dynamic indentation hardness tester is developed for characterizing materials at strain rates similar to those encountered in realistic situations. The experimental technique uses elastic stress wave propagation phenomena in a slender rod. The technique is designed to deliver a single indentation load of 100-200 mus duration. Similar to static measurements, the dynamic hardness is determined from the measured load and indentation size. Hardness measurements on a range of metals have revealed that the dynamic hardness is consistently greater than the static hardness. The increase in hardness is strongly dependent on the crystal structure of the material. The observed trends in hardness are also found to be consistent with the yield and flow stresses of these materials under uniaxial compression. Therefore, it is suggested that the current technique can be used to assess the rate sensitive nature of engineering materials. To further characterize the plastic strains within the indentation volume, static microhardness measurements were also performed within this region. The contours of microhardness indicated that the plastic zone beneath the indenter is typically smaller under dynamic conditions compared to static loading for rate sensitive materials. To assess the influence of the elastic modulus, yield stress, and work hardening coefficient on the induced plastic volume, finite element simulations were performed using the explicit finite element code LS-DYNA3D. The parametric study revealed that the yield stress has the most significant influence on the size and shape of the plastic zone. The above microstructural and numerical results can be used as guidelines for proper selection and design of engineering materials in applications involving high strain rate loading. Moreover, the contours of microhardness variation can be used to verify the suitability of analytical models developed for characterizing the deformation behavior of engineering materials under complex three dimensional loads.

Koeppel, Brian James

330

Composite shell spacecraft seat  

NASA Technical Reports Server (NTRS)

A two-part seat (10) providing full body support that is specific for each crew member (30) on an individual basis. The two-part construction for the seat (10) can accommodate many sizes and shapes for crewmembers (30) because it is reconfigurable and therefore reusable for subsequent flights. The first component of the two-part seat construction is a composite shell (12) that surrounds the crewmember's entire body and is generically fitted to their general size in height and weight. The second component of the two-part seat (10) is a cushion (20) that conforms exactly to the specific crewmember's entire body and gives total body support in more complex environment.

Barackman, Victor J. (Inventor); Pulley, John K. (Inventor); Simon, Xavier D. (Inventor); McKee, Sandra D. (Inventor)

2008-01-01

331

The Young Outer Disk of M83  

NASA Astrophysics Data System (ADS)

Deep near-infrared images recorded with NICI on Gemini South are used to investigate the evolved stellar content in the outer southeast quadrant of the spiral galaxy M83. A diffuse population of asymptotic giant branch (AGB) stars is detected, indicating that there are stars outside of the previously identified young and intermediate age star clusters in the outer disk. The brightest AGB stars have M K >= -8, and the AGB luminosity function (LF) is well matched by model LFs that assume ages <=1 Gyr. The specific star formation rate (SFR) during the past few Gyr estimated from AGB star counts is consistent with that computed from mid-infrared observations of star clusters at similar radii, and it is concluded that the disruption timescale for star clusters in the outer disk is Lt1 Gyr. The LF and specific frequency of AGB stars vary with galactocentric radius, in a manner that is indicative of lower luminosity-weighted ages at larger radii. Modest numbers of red supergiants are also found, indicating that there has been star formation during the past 100 Myr, while the ratio of C stars to M giants is consistent with that expected for a solar metallicity system that has experienced a constant SFR for the past few Gyr. The results drawn from the properties of resolved AGB stars are broadly consistent with those deduced from integrated light observations in the UV. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a co-operative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council of Canada (Canada), CONICYT (Chile), the Australian Research Council (Australia), the Ministerio da Ciencia e Technologia (Brazil), and the Ministerio de Ciencia, Tecnologia e Innovacion Productiva (Argentina).

Davidge, T. J.

2010-08-01

332

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

333

TESTING HARDNESS OF METAL ITEMS WITH MET-UD COMBINED PORTABLE HARDNESS TESTER  

Microsoft Academic Search

A new approach to portable hardness testers has been developed and introduced. It makes it possible to inspect hardness by one and the same hardness tester applying both, the ultrasonic contact impedance method and rebound method. Hardness tester wide possibilities which allow to inspect hardness of metal and alloy products with all standardized scales (Rockwell, Brinell, Vickers and Shore) have

Edward Aslanyan; Alexander Doynikov; Victor Pivovarov

334

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

335

Overview of 2008 Outer Planet Flagship Studies  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the process involved in the Phase-2 studies for the next Outer Planets Flagship (OPF). These studies will be a cooperative effort with ESA and JAXA in partnership with NASA. The annoucement of oppurtunity (AO) for the science instruments and the launch approval/planetary protection processes are reviewed. There is also discussion about capturing relevant lessons from the Cassini team, supporting international collaboration, and support for science definition teams. Some mission specific tasks are also reviewed, for the three missions being proposed: (1) Europa Explorer, (2) Jupiter System Observer and (3) Titan Explorer. A timeline for the studies is also included.

Reh, Kim R.

2008-01-01

336

Outer planet spacecraft temperature testing and analysis  

NASA Technical Reports Server (NTRS)

Unmanned spacecraft flown on missions to the outer planets of the solar system have included flybys, planetary orbiters, and atmospheric probes during the last three decades. The thermal design, test, and analysis approach applied to these spacecraft evolved from the passive thermal designs applied to the earlier lunar and interplanetary spacecraft. The inflight temperature data from representative sets of engineering subsystems and science instruments from a subset of these spacecraft are compared to those obtained during the ground test programs and from the prelaunch predictions. Several lessons are presented with specific recommendations for considerations for new projects to aid in the planning of cost effective temperature design, test, and analysis programs.

Hoffman, A. R.; Avila, A.

2002-01-01

337

New fuzzy shell clustering algorithms for boundary detection and pattern recognition  

NASA Astrophysics Data System (ADS)

In this paper, we introduce new hard and fuzzy clustering algorithms called the c-quadric shells (CQS) algorithms. These algorithms are specifically designed to seek clusters that can be described by segments of second-degree curves, or more generally by segments of shells of hyperquadrics. Previous shell clustering algorithms have considered clusters of specific shapes such as circles (the fuzzy c-shells algorithm) or ellipses (the fuzzy c-ellipsoids algorithm). The advantage of our algorithm lies in the fact that it can be used to cluster mixtures of all types of hyperquadrics such as hyperspheres, hyperellipsoids, hyperparaboloids, hyperhyperboloids, and even hyperplanes. Several examples of clustering in the two-dimensional case are shown.

Krishnapuram, Raghu J.; Frigui, Hichem; Nasraoui, Olfa

1992-02-01

338

Metrics for Hard Goods Merchandising.  

ERIC Educational Resources Information Center

Designed to meet the job-related metric measurement needs of students interested in hard goods merchandising, this instructional package is one of five for the marketing and distribution cluster, part of a set of 55 packages for metric instruction in different occupations. The package is intended for students who already know the occupational…

Cooper, Gloria S., Ed.; Magisos, Joel H., Ed.

339

Is Carbon Hard or Soft?  

NSDL National Science Digital Library

The representation shows differences in the arrangement of carbon atoms that make up diamonds and graphite. Through text and pictures, the resource describes the difference in arrangement of two different carbon allotropes. The text relates the differences in arrangements to differences in the hardness (properties) of the materials.

340

Playing the Numbers: Hard Choices  

ERIC Educational Resources Information Center

Stateline.org recently called this recession the worst in 50 years for state budgets. As has been the case in past economic downturns, higher education looks to be particularly hard hit. Funds from the American Recovery and Relief Act may have postponed some of the difficulty for many colleges and universities, but the outlook for public higher…

Doyle, William R.

2009-01-01

341

Measuring the Hardness of Softballs  

Microsoft Academic Search

The following describes a method that may be used to measure the hardness and elasticity of balls with application to softballs. While standardized test methods currently exist to measure these properties, they do not represent the ball deformation rate and magnitude that occurs in play. The method described herein involves impacting a fixed solid cylinder (matched to the diameter of

Lloyd V. Smith

342

Ejs Hard Disk Collision Model  

NSDL National Science Digital Library

The Ejs Hard Disk Collision model displays a two-dimensional collision between two hard disks. The two disks have the same mass and only one mass is moving at the beginning of the simulation. The impact of the collision is offset by the impact parameter, b, which can be changed. The center-of-mass of the two masses is also shown. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Hard Disk Collision model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_newton_HardDiskCollision.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for Newtonian mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-07-06

343

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

344

Microencapsulation process factors which influence the sphericity of 1 mm o.d. poly({alpha}-methylstyrene) shells for ICF  

SciTech Connect

The authors have identified three process variables which determine the sphericity of polymer shells made by dual orifice microencapsulation. (1) The density mismatch between the outer aqueous solution and the polymer oil phase must be minimized. They have minimized this density mismatch by adjusting the water bath temperature. (2) The stir rate has an effect, with a minimum non-sphericity located near 50--70 rpm stir rate. (3) The outer aqueous solution must have enough total oil solvent (fluorobenzene in the drops) to be beyond the aqueous saturation level (1.5 g/{ell}) at the beginning of the solvent extraction. Using the optimal conditions for a 1000 {micro}m o.d. shell, they produce a minimum variation in the radius of a given shell, in the neighborhood of 0.4 {micro}m.

McQuillan, B.W.; Greenwood, A. [General Atomics, San Diego, CA (United States)

1999-03-01

345

REPAD: An empirical model of pitch angle distributions for energetic electrons in the Earth's outer radiation belt  

NASA Astrophysics Data System (ADS)

have recently conducted a statistical survey on pitch angle distributions of energetic electrons trapped in the Earth's outer radiation belt, and a new empirical model was developed based upon survey results. This model—relativistic electron pitch angle distribution (REPAD)—aims to present statistical pictures of electron equatorial pitch angle distributions, instead of the absolute flux levels, as a function of energy, L shell, magnetic local time, and magnetic activity. To quantify and facilitate this statistical survey, we use Legendre polynomials to fit long-term in situ directional fluxes observed near the magnetic equator from three missions: CRRES, Polar, and LANL-97A. As the first of this kind of model, REPAD covers the whole outer belt region, providing not only the mean and median pitch angle distributions in the area but also error estimates of the average distributions. Preliminary verification and validation results demonstrate the reliable performance of this model. Usage of REPAD is mainly to predict the full pitch angle distribution of fluxes along a given magnetic field line, or even on a given drift shell, based upon one single unidirectional or omnidirectional flux measurement anywhere on that field line. This can be particularly useful for data assimilation, which usually has large tolerance on data errors. In addition, relatively small variations in pitch angle distributions measured at L shell between ~ 4 and 5 justify the assumption of fixed pitch angle distributions at GPS equatorial crossings (L ~ 4.2) used in our previous studies.

Chen, Yue; Friedel, Reiner H. W.; Henderson, Michael G.; Claudepierre, Seth G.; Morley, Steven K.; Spence, Harlan E.

2014-03-01

346

Outer core compositional layering and constraints on core liquid transport properties  

NASA Astrophysics Data System (ADS)

A variety of studies of the Earth's outer core report wave speeds near the top of the core slightly lower than reference models for core properties. One interpretation of the slower wavespeed profile is that it could represent a change in the core's light element concentration with depth in the core. I explore the consequences of this idea by interpreting the velocity profile as arising from diffusion gradients imposed in the outer core by various mechanisms. In order to estimate relative diffusion rates for light elements in liquid iron I also examine theories for transport properties of high pressure metallic liquids that are based on hard-sphere models. From the seismic wavespeed profile, an effective diffusivity may be obtained, which ranges from 0.1 to 10×10-7 m s depending on the particular boundary condition or initial condition chosen. The upper bound of the range is higher than expected from high pressure experiments and models of diffusivity in liquid metals for all elements except H. The lower bound is within the uncertainty of theoretical predictions and experimental determinations given the range of expected outer core temperatures if diffusion involves low Z elements. Plausible agreement arises from a class of models that represent diffusion out of a compositionally different layer existing from the time of the formation of the Earth. If the wavespeed profile in the core is diffusive in nature, the data suggest that it is an original feature of the core.

Helffrich, George

2014-04-01

347

Outer core compositional layering and constraints on core liquid transport properties  

NASA Astrophysics Data System (ADS)

A variety of studies of the Earth's outer core report wave speeds near the top of the core slightly lower than reference models for core properties. One interpretation of the slower wavespeed profile is that it could represent a change in the core's light element concentration with depth in the core. I explore the consequences of this idea by interpreting the velocity profile as arising from diffusion gradients imposed in the outer core by various mechanisms. I also examine theories for transport properties of high pressure metallic liquids that are based on hard-sphere models. These theories predict core diffusivities on the order of 1 - 20 × 10-9 m2s-1. From the seismic wavespeed profile, an effective diffusivity may be obtained, which ranges from 0.1 - 10 × 10-7 m2s-1 depending on the particular boundary condition or initial condition chosen. The upper bound on the range is much higher than expected from high pressure experiments and models of diffusivity in liquid metals. The lower bound is within the uncertainty of theoretical predictions and experimental determinations given the range of expected outer core temperatures if diffusion involves low Z elements. Plausible agreement arises from a class of models that represent diffusion out of a compositionally different layer existing from the time of the formation of the Earth. If the wavespeed profile in the core is diffusive in nature, the data suggest that it is an original feature of the core.

Helffrich, George

2014-05-01

348

Pyrocarbon-coating on powdery hard-carbon using chemical vapor infiltration and its electrochemical characteristics  

Microsoft Academic Search

Using the pressure-pulsed chemical vapor infiltration technique, thin pyrocarbon films were coated on the surface of the hard-carbon particles. The crystallinity of pyrocarbon shell was higher than that of the core carbon. The BET surface area and the pores with the diameter of 1.5–5nm were extremely decreased after coating with 7wt.% pyrocarbon. These changes in the nano-scaled structure of carbon

Yoshimi Ohzawa; Yasuyuki Yamanaka; Kazuhisa Naga; Tsuyoshi Nakajima

2005-01-01

349

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

350

Glass shell manufacturing in space  

NASA Technical Reports Server (NTRS)

Highly-uniform, hollow glass spheres (shells), which are used for inertial confinement fusion targets, were formed from metal-organic gel powder feedstock in a vertical furnace. As a result of the rapid pyrolysis caused by the furnace, the gel is transformed to a shell in five distinct stages: (a) surface closure of the porous gel; (b) generation of a closed-cell foam structure in the gel; (c) spheridization of the gel and further expansion of the foam; (d) coalescence of the closed-cell foam to a single-void shell; and (e) fining of the glass shell. The heat transfer from the furnace to the falling gel particle was modeled to determine the effective heating rate of the gel. The model predicts the temperature history for a particle as a function of mass, dimensions, specific heat, and absorptance as well as furnace temperature profile and thermal conductivity of the furnace gas. A model was developed that predicts the gravity-induced degradation of shell concentricity in falling molten shells as a function of shell characteristics and time.

Downs, R. L.; Ebner, M. A.; Nolen, R. L., Jr.

1981-01-01

351

Baroplastic core-shell nanoparticles  

NASA Astrophysics Data System (ADS)

A novel class of baroplastic core-shell nanoparticles was designed based on the pressure-induced miscibility between a low Tg component core and a high Tg component shell and obtained by a two-stage miniemulsion polymerization technique. By changing the amount of surfactant and monomer feed ratio, the size and composition of core-shell nanoparticles were controlled and almost homogenous particles with very narrow particle size distribution were obtained in each synthetic step. Trilayerd core-shell nanoparticles, which have an additional inner-core, were also successfully synthesized by sequential addition of monomers. The baroplasticity of these core-shell nanoparticles was demonstrated by compression molding and characterized by SANS, DSC, and TEM. Transparent objects were molded at temperatures as low as 25 oC under 5000 psi pressure, and recycled up to 10 times, from poly(n-butyl acrylate)/polystyrene or poly(2-ethyl hexyl acrylate)/polystyrene systems. The particle size was found to play an important role to determine the optical and mechanical properties of the resulting product. By comparison with bilayered core-shell nanoparticles, improved mechanical properties were observed in trilayered systems due to the enlarged interface region. Finally, blend or hybrid baroplastic core-shell nanoparticles were prepared incorporating other polymer or inorganic nanoparticles.

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

2004-03-01

352

T2K Outer Detector Events  

NASA Astrophysics Data System (ADS)

In the long-baseline neutrino oscillation experiment, T2K, the Super-Kamiokande (Super-K) detector is used to detect neutrino interactions from a beam originating 295 km away. Super-K is a 50 kTon water Cerenkov detector originally built to observe proton decay, and to study atmospheric, solar and supernova neutrinos. As a result, it is divided into two segments: a cylindrical inner volume, termed the Inner Detector (ID), nested inside another cylindrical outer volume, termed the Outer Detector (OD). Typically, the OD's role in physics studies at Super-K is to act as a cosmic ray veto for the ID. However, in the T2K experiment neutrino interactions originating from the beam occur within a small, well-known time window. Accepting only coincident events with the beam into the T2K data sample provides a large enough suppression to the background rate that events containing light in the OD can still be considered as coming from neutrino interactions. From volume considerations alone, including such OD events provides an additional number of events comparable to the number of events expected in the ID. In this talk, I will describe the techniques used to separate neutrino events in the OD from the relatively small amount of backgrounds and present the results of these techniques from the first phase of data taking.

Wongjirad, Taritree

2011-04-01

353

Lateral interactions in the outer retina  

PubMed Central

Lateral interactions in the outer retina, particularly negative feedback from horizontal cells to cones and direct feed-forward input from horizontal cells to bipolar cells, play a number of important roles in early visual processing, such as generating center-surround receptive fields that enhance spatial discrimination. These circuits may also contribute to post-receptoral light adaptation and the generation of color opponency. In this review, we examine the contributions of horizontal cell feedback and feed-forward pathways to early visual processing. We begin by reviewing the properties of bipolar cell receptive fields, especially with respect to modulation of the bipolar receptive field surround by the ambient light level and to the contribution of horizontal cells to the surround. We then review evidence for and against three proposed mechanisms for negative feedback from horizontal cells to cones: 1) GABA release by horizontal cells, 2) ephaptic modulation of the cone pedicle membrane potential generated by currents flowing through hemigap junctions in horizontal cell dendrites, and 3) modulation of cone calcium currents (ICa) by changes in synaptic cleft proton levels. We also consider evidence for the presence of direct horizontal cell feed-forward input to bipolar cells and discuss a possible role for GABA at this synapse. We summarize proposed functions of horizontal cell feedback and feed-forward pathways. Finally, we examine the mechanisms and functions of two other forms of lateral interaction in the outer retina: negative feedback from horizontal cells to rods and positive feedback from horizontal cells to cones.

Thoreson, Wallace B.; Mangel, Stuart C.

2012-01-01

354

Crack problems in cylindrical and spherical shells  

NASA Technical Reports Server (NTRS)

Standard plate or shell theories were used as a starting point to study the fracture problems in thin-walled cylindrical and spherical shells, assuming that the plane of the crack is perpendicular to the surface of the sheet. Since recent studies have shown that local shell curvatures may have a rather considerable effect on the stress intensity factor, the crack problem was considered in conjunction with a shell rather than a plate theory. The material was assumed to be isotropic and homogeneous, so that approximate solutions may be obtained by approximating the local shell crack geometry with an ideal shell which has a solution, namely a spherical shell with a meridional crack, a cylindrical shell with a circumferential crack, or a cylindrical shell with an axial crack. A method of solution for the specially orthotropic shells containing a crack was described; symmetric and skew-symmetric problems are considered in cylindrical shells with an axial crack.

Erdogan, F.

1976-01-01

355

MicroShell Minimalist Shell for Xilinx Microprocessors  

NASA Technical Reports Server (NTRS)

MicroShell is a lightweight shell environment for engineers and software developers working with embedded microprocessors in Xilinx FPGAs. (MicroShell has also been successfully ported to run on ARM Cortex-M1 microprocessors in Actel ProASIC3 FPGAs, but without project-integration support.) Micro Shell decreases the time spent performing initial tests of field-programmable gate array (FPGA) designs, simplifies running customizable one-time-only experiments, and provides a familiar-feeling command-line interface. The program comes with a collection of useful functions and enables the designer to add an unlimited number of custom commands, which are callable from the command-line. The commands are parameterizable (using the C-based command-line parameter idiom), so the designer can use one function to exercise hardware with different values. Also, since many hardware peripherals instantiated in FPGAs have reasonably simple register-mapped I/O interfaces, the engineer can edit and view hardware parameter settings at any time without stopping the processor. MicroShell comes with a set of support scripts that interface seamlessly with Xilinx's EDK tool. Adding an instance of MicroShell to a project is as simple as marking a check box in a library configuration dialog box and specifying a software project directory. The support scripts then examine the hardware design, build design-specific functions, conditionally include processor-specific functions, and complete the compilation process. For code-size constrained designs, most of the stock functionality can be excluded from the compiled library. When all of the configurable options are removed from the binary, MicroShell has an unoptimized memory footprint of about 4.8 kB and a size-optimized footprint of about 2.3 kB. Since MicroShell allows unfettered access to all processor-accessible memory locations, it is possible to perform live patching on a running system. This can be useful, for instance, if a bug is discovered in a routine but the system cannot be rebooted: Shell allows a skilled operator to directly edit the binary executable in memory. With some forethought, MicroShell code can be located in a different memory location from custom code, permitting the custom functionality to be overwritten at any time without stopping the controlling shell.

Werne, Thomas A.

2011-01-01

356

A magnetic, luminescent and mesoporous core–shell structured composite material as drug carrier  

Microsoft Academic Search

In this paper, hydrothermal synthesized Fe3O4 microspheres have been encapsulated with nonporous silica and a further layer of ordered mesoporous silica through a simple sol–gel process. The surface of the outer silica shell was further functionalized by the deposition of YVO4:Eu3+ phosphors, realizing a sandwich structured material with mesoporous, magnetic and luminescent properties. The multifunctional system was used as drug

Piaoping Yang; Zewei Quan; Zhiyao Hou; Chunxia Li; Xiaojiao Kang; Ziyong Cheng; Jun Lin

2009-01-01

357

An experimental and theoretical study of the valence shell photoelectron spectrum of tetrafluoromethane  

Microsoft Academic Search

The complete valence shell photoelectron spectrum of tetrafluoromethane has been recorded using synchrotron radiation and the observed structure has been interpreted using ionisation energies and relative spectral intensities computed using the third-order algebraic-diagrammatic-construction (ADC(3)) scheme for the one-particle Green’s function and the outer valence Green’s function (OVGF) method. The ADC(3) calculations were performed using both the original variant based on

D. M. P. Holland; A. W. Potts; A. B. Trofimov; J. Breidbach; J. Schirmer; R. Feifel; T. Richter; K. Godehusen; M. Martins; A. Tutay; M. Yalcinkaya; M. Al-Hada; S. Eriksson; L. Karlsson

2005-01-01

358

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

2013-01-01

359

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

360

Hypersonic vibrations of Ag@SiO2 (cubic core)-shell nanospheres.  

PubMed

The intriguing optical and catalytic properties of metal-silica core-shell nanoparticles, inherited from their plasmonic metallic cores together with the rich surface chemistry and increased stability offered by their silica shells, have enabled a wide variety of applications. In this work, we investigate the confined vibrational modes of a series of monodisperse Ag@SiO(2) (cubic core)-shell nanospheres synthesized using a modified Sto?ber sol-gel method. The particle-size dependence of their mode frequencies has been mapped by Brillouin light scattering, a powerful tool for probing hypersonic vibrations. Unlike the larger particles, the observed spheroidal-like mode frequencies of the smaller ones do not scale with inverse diameter. Interestingly, the onset of the deviation from this linearity occurs at a smaller particle size for higher-energy modes than for lower-energy ones. Finite element simulations show that the mode displacement profiles of the Ag@SiO(2) core-shells closely resemble those of a homogeneous SiO(2) sphere. Simulations have also been performed to ascertain the effects that the core shape and the relative hardness of the core and shell materials have on the vibrations of the core-shell as a whole. As the vibrational modes of a particle have a bearing on its thermal and mechanical properties, the findings would be of value in designing core-shell nanostructures with customized thermal and mechanical characteristics. PMID:21087022

Sun, Jing Ya; Wang, Zhi Kui; Lim, Hock Siah; Ng, Ser Choon; Kuok, Meng Hau; Tran, Toan Trong; Lu, Xianmao

2010-12-28

361

Radio seismology of the outer solar corona  

NASA Astrophysics Data System (ADS)

Observed oscillations of coronal loops in extreme ultraviolet (EUV) lines have been successfully used to estimate plasma parameters in the inner corona (< 0.2R0, where R0 is the solar radius). However, coronal seismology in EUV lines fails for higher altitudes because of rapid decrease in line intensity. We aim to use radio observations to estimate the plasma parameters of the outer solar corona (> 0.2R0). 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. 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 (MHD) 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 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. 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. The research leading to these results has received funding from the Austrian 'Fonds zur Förderung der wissenschaftlichen Forschung' under project P24740-N27.

Zaqarashvili, Teimuraz; Melnik, Valentin; Brazhenko, Anatoliy; Panchenko, Mykhaylo; Konovalenko, Alexander; Dorovskyy, Vladimir; Rucker, Helmut

2014-05-01

362

THE OUTER DISKS OF DWARF IRREGULAR GALAXIES  

SciTech Connect

In order to explore the properties of extreme outer stellar disks, we obtained ultra-deep V and GALEX ultraviolet (UV) images of four dwarf irregular galaxies and one blue compact dwarf galaxy, and ultra-deep B images of three of these. Our V-band surface photometry extends to 29.5 mag arcsec{sup -2}. We convert the FUV and V-band photometry, along with H{alpha} photometry obtained in a larger survey, into radial star formation rate profiles that are sensitive to timescales from 10 Myr to the lifetime of the galaxy. We also obtained H I-line emission data and compare the stellar distributions, surface brightness profiles, and star formation rate profiles to H I-line emission maps, gas surface density profiles, and gas kinematics. Our data lead us to two general observations. First, the exponential disks in these irregular galaxies are extraordinarily regular. We observe that the stellar disks continue to decline exponentially as far as our measurements extend. In spite of lumpiness in the distribution of young stars and H I distributions and kinematics that have significant unordered motions, sporadic processes that have built the disks-star formation, radial movement of stars, and perhaps even perturbations from the outside-have, nevertheless, conspired to produce standard disk profiles. Second, there is a remarkable continuity of star formation throughout these disks over time. In four out of five of our galaxies the star formation rate in the outer disk measured from the FUV tracks that determined from the V-band, to within factors of five, requiring star formation at a fairly steady rate over the galaxy's lifetime. Yet, the H I surface density profiles generally decline with radius more shallowly than the stellar light, and the gas is marginally gravitationally stable against collapse into clouds. Outer stellar disks are challenging our concepts of star formation and disk growth and provide a critical environment in which to understand processes that mold galaxy disks.

Hunter, Deidre A.; Massey, Philip; Wilsey, Nick; Riabokin, Malanka [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Elmegreen, Bruce G. [IBM T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Oh, Se-Heon [Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701, Republic of South Africa (South Africa); Anderson, Ed [Department of Physics and Astronomy, Northern Arizona University, P.O. Box 6010, Flagstaff, AZ 86011-6010 (United States); Nordgren, Tyler E., E-mail: dah@lowell.edu, E-mail: phil.massey@lowell.edu, E-mail: njw459@truman.edu, E-mail: riabokin@msu.edu, E-mail: bge@watson.ibm.com, E-mail: seheon-oh@ast.uct.ac.za, E-mail: Ed.Anderson@nau.edu, E-mail: tyler_nordgren@redlands.edu [Department of Physics, University of Redlands, 1200 East Colton Avenue, Redlands, CA 92373 (United States)

2011-10-15

363

Shell design of functional hyperbranched molecules for surface assembly  

NASA Astrophysics Data System (ADS)

This study explores possibilities of obtaining of unique self-assembled, nanofibrillar structures from amphiphilic hyperbranched molecules on solid surfaces. To achieve this, we explore the multifunctional properties of hyperbranched polymers which are determined by the nature of the end groups and structure of the chemical composition of the core unit. We established that the combination of hydrophobic interactions and multiple hydrogen bonding events added to the dendritic core structure is responsible for stable assembling into nanofibrillar morphology at the air-water interface at both the nano and at microscales and determined compositional boundaries of this phenomenon. The core-shell architecture of the amphiphilic dendritic molecules suggested here provides exceptional stability of one-dimensional nanofibrillar structures. The critical condition for the formation of the nanofibrillar structures is the presence of both alkyl tails in the outer shell as the hydrophobic component and either amine or carboxyl groups in the shell as the hydrophilic component. The multiple intermolecular hydrogen bonding and polar interactions between flexible cores stabilize these nanofibers and make them robust against surface pressure and solvents. Moreover, discovered assembled nano-fibers formed by hyperbranched polymers have been used for templating of silver nanoparticles via growth from water subphase. We observed that hyperbranched polymers scaffolds can create aligned nanoparticle arrays, and also effectively control size of the particles to about 3 nm.

Ornatska, Maryna

364

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 dialectric break ring, and a pair of threaded ring sections. 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.

Arnold, Phillip A. (Livermore, CA); Anderson, Andrew T. (Livermore, CA); Alger, Terry W. (Tracy, CA)

1994-01-01

365

Transpecific microsatellites for hard pines.  

PubMed

Microsatellites are difficult to recover from large plant genomes so cross-specific utilisation is an important source of markers. Fifty microsatellites were tested for cross-specific amplification and polymorphism to two New World hard pine species, slash pine ( Pinus elliottii var. elliottii) and Caribbean pine ( P. caribaea var. hondurensis). Twenty-nine (58%) markers amplified in both hard pine species, and 23 of these 29 were polymorphic. Soft pine (subgenus Strobus) microsatellite markers did amplify, but none were polymorphic. Pinus elliottii var. elliottii and P. caribaea var. hondurensis showed mutational changes in the flanking regions and the repeat motif that were informative for Pinus spp. phylogenetic relationships. Most allele length variation could be attributed to variability in repeat unit number. There was no evidence for ascertainment bias. PMID:12582642

Shepherd, M.; Cross, M.; Maguire, L.; Dieters, J.; Williams, G.; Henry, J.

2002-04-01

366

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. 12 figs.

Good, M.S.; Schuster, G.J.; Skorpik, J.R.

1997-07-08

367

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

368

Collapsing thin shells with rotation  

NASA Astrophysics Data System (ADS)

We construct exact solutions describing the motion of rotating thin shells in a fully backreacted five-dimensional rotating black hole spacetime. The radial equation of motion follows from the Darmois-Israel junction conditions, where both interior and exterior geometries are taken to be equal angular momenta Myers-Perry solutions. We show that rotation generates anisotropic pressures and momentum along the shell. Gravitational collapse scenarios including rotation are analyzed and a new class of stationary solutions is introduced. Energy conditions for the anisotropic matter shell are briefly discussed. We find that the weak energy condition is not violated for the collapse scenario where the shell starts at rest from infinity, nor for the new class of stationary solutions in anti-de Sitter. We further prove that the cosmic censorship conjecture is always satisfied in our setup.

Delsate, Térence; Rocha, Jorge V.; Santarelli, Raphael

2014-06-01

369

Rotating Bands for Artillery Shells.  

National Technical Information Service (NTIS)

This report summarizes the work completed during a preliminary investigation of the applicability of the LAYERGLAZE (trade name) process to the fabrication of copper rotating bands on titanium artillery shell bodies. Two approaches were taken, one involvi...

E. M. Breinan M. J. Kaufman

1980-01-01

370

Suzaku Detection of Diffuse Hard X-Ray Emission Outside Vela X  

NASA Technical Reports Server (NTRS)

Vela X is a large, 3 deg x 2 deg, radio-emitting pulsar wind nebula (PWN) powered by the Vela pulsar in the Vela supernova remnant. Using four Suzaku/XIS observations pointed just outside Vela X, we find hard X-ray emission extending throughout the fields of view. The hard X-ray spectra are well represented by a power-law. The photon index is measured to be constant at Gamma approximates 2.4, similar to that of the southern outer part of Vela X. The power-law flux decreases with increasing distance from the pulsar. These properties lead us to propose that the hard X-ray emission is associated with the Vela PWN. The larger X-ray extension found in this work strongly suggests that distinct populations relativistic electrons form the X-ray PWN and Vela X, as was recently inferred from multiwavelength spectral modeling of Vela X.

Katsuda, Satoru; Mori, Koji; Petre, Robert; Yamaguchi, Hiroya; Tsunemi, Hiroshi; Bocchino, Fabrizio; Bamba, Aya; Miceli, Marco; Hewitt, John W.; Temim, Tea; Uchida, Hiroyuki; Yoshii, Rie

2011-01-01

371

Turbine blade with spar and shell  

Microsoft Academic Search

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

Daniel O. Davies; Ross H. Peterson

2012-01-01

372

Production of a cylindrical plasma shell  

Microsoft Academic Search

An apparatus forming a hollow plasma shell of 3 x 2 sq cm cross section and 40 cm in diameter is presented. The plasma shell is formed by injecting a neutral gas shell of argon via 36 evenly spaced supersonic injection nozzles and ionizing this shell with a high-voltage electrical discharge. Nozzle geometry gives a Mach 6 injection which maintains

R. D. Bengtson; D. L. Honea; D. Pease; J. H. Degnan; R. A. Golobic

1980-01-01

373

Crack-tip fields in anisotropic shells  

Microsoft Academic Search

Asymptotic crack-tip fields including the effect of transverse shear deformation in an anisotropic shell are presented. The material anisotropy is defined here as a monoclinic material with a plane symmetry at x3 = 0. In general, the shell geometry near the local crack tip region can be considered as a shallow shell. Based on Reissner shallow shell theory, an asymptotic

F. G. YUAN; S. YANG

2002-01-01

374

Hard-square lattice gas  

Microsoft Academic Search

We have studied the hard-square lattice gas, using corner transfer matrices. In particular, we have obtained the first 24 terms of the high-density series for the order parameter?2-?1. From these we estimate the critical activity to be 3.7962±0.0001. This is in excellent agreement with the earlier work of Gaunt and Fisher. It conflicts with the value 4.0 given by Müller-Hartmann

R. J. Baxter; I. G. Enting; S. K. Tsang

1980-01-01

375

Hard Disk PVT System Model  

NSDL National Science Digital Library

The Hard Disk PVT System simulates a two-dimensional system of particles confined between a thermal reservoir and a piston. This computer model is designed to study the equation of state for hard disks without other interactions. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. Users can set the initial particle energy, the initial particle separation, and the thermal reservoir temperature Tr. The thermal conductivity parameter ? determines the probability that a collision with the thermal wall will affect (thermalize) the colliding particle. If the conductivity is one, the particle velocity after a reservoir collision is set according to Maxwell-Boltzmann statistics. If the conductivity is zero, all reservoir collisions are elastic and the internal energy E of the system is conserved.   Particles in this model have unit mass and interact through contact forces. Collision times are computed analytically because particles and pistons move with constant velocity between collisions. The time evolution algorithm advances the particle and piston positions from collision to collision until the requested time step ?t is achieved. The time evolution is then paused, data is accumulated, and the screen is redrawn. The Hard Disk PVT model is a supplemental simulation for the article "Pressure Oscillations in Adiabatic Compression" by Roland Stout in The Physics Teacher 49(5), 280-281 (2011) and has been approved by the author and The Physics Teacher editor. The model was developed using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_hd_HardDiskPVTSystem.jar file will run the program if Java is installed.

Christian, Wolfgang

2011-03-12

376

Microwave assisted hard rock cutting  

DOEpatents

An apparatus for the sequential fracturing and cutting of subsurface volume of hard rock (102) in the strata (101) of a mining environment (100) by subjecting the volume of rock to a beam (25) of microwave energy to fracture the subsurface volume of rock by differential expansion; and , then bringing the cutting edge (52) of a piece of conventional mining machinery (50) into contact with the fractured rock (102).

Lindroth, David P. (Apple Valley, MN); Morrell, Roger J. (Bloomington, MN); Blair, James R. (Inver Grove Heights, MN)

1991-01-01

377

Helical shell models for MHD  

Microsoft Academic Search

A shell model for magnetohydrodynamics (MHD) is derived directly from the dynamical system driving the evolution of three\\u000a helical modes interacting in a triad. The use of helical modes implies that two shell variables are required for the velocity\\u000a as well as for the magnetic field. The advantage of the method is the automatic conservation of all the ideal quadratic

T. Lessinnes; F. Plunian; D. Carati

2009-01-01

378

How Many Under the Shell?  

NSDL National Science Digital Library

This interactive Flash applet helps students develop number sense and fluency with addition and subtraction facts within 10. Okta hides some bubbles under a shell, and then either adds more bubbles or takes some away. Students determine how many bubbles are left under the shell. Users can choose a specific one-digit starting number or let the applet choose randomly. Users can select addition, subtraction or both.

2000-01-01

379

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.

380

Plastic buckling of cylindrical shells  

Microsoft Academic Search

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,

K. Bandyopadhyay; J. Xu; S. Shteyngart; H. Eckert

1994-01-01

381

The progressive outer retinal necrosis syndrome.  

PubMed

The progressive outer retinal necrosis (PORN) syndrome is a recently described clinical variant of necrotizing herpetic retinopathy in patients with the acquired immunodeficiency syndrome (AIDS). It is caused by varicellazoster virus infection of the retina. Its course and clinical features distinguish it from the acute retinal necrosis syndrome and CMV retinopathy. Early disease is characterized by multifocal deep retinal opacification. Lesions rapidly coalesce and progress to total retinal necrosis over a short period of time. Despite aggressive therapy with intravenous antivirial drugs, prognosis is poor; disease progression and/or recurrence is common, and the majority of patients develop no light perception vision. Total retinal detachments are common. Prophylaxis against retinal detachment using laser retinopexy has not been useful in most cases. PORN syndrome is an uncommon, but devastating complication of AIDS. PMID:7852023

Holland, G N

1994-01-01

382

Photometric properties of outer planetary satellites  

NASA Technical Reports Server (NTRS)

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 Phoebe has a rotational lightcurve with period near either 11.25 or 21.1 hr. For U4 and N1 there is evidence for a lightcurve synchronous with the orbital revolution. The seven brighter Saturnian satellites show a regular relation between the ultraviolet dropoff and distance to the planet, probably related with differences in the rock component on their surfaces.

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

1980-01-01

383

Near infrared imaging of the outer planets  

NASA Technical Reports Server (NTRS)

In the last year we have continued our program of near infrared imaging of the outer planets of the solar system. Uranus is virtually invisible at 2.3 microns, showing that the methane is an effective absorber of the incident sunlight and that there is very little aerosol content in the upper atmosphere. On the other hand, Neptune shows a haze present over the entire Northern Hemisphere at 2.3 microns. This leads to the inference that there is an aerosol layer at a high altitude. We have recovered the Neptune satellite, 1989 N1, which was first discovered in Voyager images. The satellite is exceedingly faint in the near infrared, and was detectable only because the planet itself was comparatively faint at this wavelength. Observations of this satellite, coupled with the Voyager images, permit us to substantially refine the satellite's orbit, and hence carefully probe the gravitational field of Neptune.

Matthews, K.; Soifer, B. T.

1991-01-01

384

Variability in the outer planet aurorae  

NASA Technical Reports Server (NTRS)

Multiwavelength observations of the aurorae of the outer planets are reviewed emphasizing the findings on physical processes derived from specific wavelengths. The review examines features of the auroral zones such as ionospheric currents, atmospheric heating, and compositional changes in the aurorae of Jupiter, Saturn, Uranus, Neptune, and the earth for comparison. Jupiter's multiwavelength aurora receives special attention since recent observations shed light on the distribution of the UV auroral ovals, the spectroscopy of the UV auroral emissions, auroral dynamics and ion upwelling, and IR emission from auroral latitudes. The observational data on Jupiter facilitate the modeling of variability and detailed thermospheric and magnetospheric processes. Saturn can be studied by extending findings fron Jupiter's aurora, and deficiencies are found in the observational datasets for Neptune and Uranus.

Clarke, John T.

1992-01-01

385

Radial diffusion coefficients in the outer heliosphere  

NASA Astrophysics Data System (ADS)

When cosmic ray streaming in the heliosphere is negligible, the basic onedimensional transport model gives a simple approximation for the diffusion coefficient of cosmic ray particles, ~Zrr=CVSW/gr, where C is the Compton-Gettiing factor, VSW is the solar wind velocity and gr is the radial intensity gradients. In a separate paper at this conference we made detailed measurement of radial intensity gradients in the outer heliosphere from the combined data set observed over the solar activity minima of 1977/1997(qA>0). Using these detailed gradients and onedimensional transport model we calculate the diffusion coefficients in the outerheliosphere. These diffusion coefficients are compared with those of 1987 to also search for drift effects as manifested over two successive solar minima periods

Fujii, Z.; McDonald, F. B.; Moraal, H.

2001-08-01

386

UMass at TREC 2003: HARD and QA.  

National Technical Information Service (NTIS)

The Center for Intelligent Information Retrieval (CIIR) at UMass Amherst participated in two tracks for TREC 2003: High Accuracy Retrieval from Documents (HARD) and Question Answering (QA). In the HARD track, we developed document metadata to correspond t...

A. Corrada-Emmanuel C. Wade N. AbdulJaleel Q. Li X. Liu

2003-01-01

387

Hardness of Electrodeposited Nano-Nickel Revisited  

NASA Astrophysics Data System (ADS)

In the past, hardness measurements on nanocrystalline metals were limited to Vickers microhardness and nano-indentation tests, mainly due to sample size/thickness limitations. On the other hand, most industries require hardness values on the Rockwell scale and make extensive use of hardness conversion relationships for various hardness scales. However, hardness conversions currently do not exist for nanocrystalline metals. With recent advances in electrodeposition technology, thicker specimens with a wide range of grain sizes can now be produced. In this study, the relationships between Vickers and Rockwell hardness scales have been developed for such materials. In addition, hardness indentations were used to gain further insight into the work hardening of nanocrystalline and polycrystalline nickel. Vickers microhardness and nano-indentation profiles below large Rockwell indentations showed that polycrystalline nickel exhibited considerable strain hardening, as expected. On the other hand, for nanocrystalline nickel the micro-Vickers and nano-indentations hardness profile showed low strain hardening capacity.

Tang, Bill Tsz Fai

388

Outer Planet Mission Studies Neptune Aerocapture  

NASA Technical Reports Server (NTRS)

Current and previous studies of orbiter missions to the outer planets have clearly identified high-energy aerocapture as a critical and enabling technology. Aerocapture involves the use of aerodynamic lift to fly a trajectory through a planet's atmosphere to sufficiently decelerate an entry vehicle to capture into planetary orbit. In the past, numerous studies of different configurations of lifting entry vehicles were studied for various planetary orbiter missions which identified aerocapture as a feasible concept yet complex and technically challenging. In order to determine the feasibility of high-speed aerocapture at the outer planets, an accurate trajectory simulation of the flight vehicle is the critical first step in the proposed research. Vehicle response to aerodynamic loading must be predicted accurately in the trajectory simulations. For several Neptune orbiter missions currently under study at the Jet Propulsion Laboratory (JPL), entry velocities relative to the rotating atmosphere ranging from 25 to 30 km/sec, are to be expected. Preliminary trajectory analysis has identified the various flow regimes the entry vehicle is expected to fly in the 8 1% H2 and 19% He atmosphere of Neptune. The size and mass of the vehicle are also determined by the launch vehicle constraints and orbiter spacecraft requirements. For a given baseline arrival conditions of an inertial entry velocity of 28 km/sec and an entry mass of 400 kg, a medium lift (L/D = 1), axisymmetric biconic shaped vehicle was selected in order to satisfy entry corridor width requirements expected for Neptune aerocapture. The analysis summarized in this study indicates that a biconic entry vehicle is a feasible concept for a Neptune aerocapture orbiter mission. The preliminary entry trajectory simulations has demonstrated adequate entry corridor control authority. Furthermore, estimates of the stagnation point heating environment has enabled the preliminary selection of candidate lightweight ceramic TPS materials.

Wercinski, Paul F.; Langhoff, Steven R. (Technical Monitor)

1997-01-01

389

The Outer Planetary Mission Design Project  

NASA Astrophysics Data System (ADS)

With the recent focus from the planetary science community on the outer planets of the solar system, The University of Alabama in Huntsville Integrated Product Team program is embarking on a new challenge to develop an outer planetary mission for the academic year 2010-2011. Currently four bodies are of interest for this mission: Titan, Europa, Triton, and Enceledus, with one body being chosen by the instructors by the beginning of the fall semester. This project will use the 2010 Discovery Announcement of Opportunity as its Request for Proposal (RFP). All of the teams competing in this project will use the AO to respond with a proposal to the instructors for their proposed mission and spacecraft concept. The project employs the two-semester design sequence of the IPT program to provide a framework for the development of this mission. This sequence is divided into four phases. Phase 1 - Requirements Development - focuses on the development of both the scientific and engineering requirements of the mission. During this phase the teams work very closely with the PI organization, represented by the College of Charleston. Phase 2 - Team Formation and Architecture Development - concentrates on the assessment of the overall mission architecture from the launch vehicle to the ground operations of the proposed spacecraft. Phase 3 - System Definition - provides for spacecraft subsystem trade studies and further refinement of the specific spacecraft to meet the scientific requirements and objectives developed in Phase 1. Phase 4 - Design - is the phase where the engineers provide the spacecraft design that is required for the mission of interest. At the conclusion of Phases 2 and 4, an external review board evaluates the proposed designs and chooses one winner of the competition.

Benfield, Michael; Turner, M. W.

2010-10-01

390

Nuclear Electric Propulsion for Outer Space Missions  

NASA Technical Reports Server (NTRS)

Today we know of 66 moons in our very own Solar System, and many of these have atmospheres and oceans. In addition, the Hubble (optical) Space Telescope has helped us to discover a total of 100 extra-solar planets, i.e., planets going around other suns, including several solar systems. The Chandra (X-ray) Space Telescope has helped us to discover 33 Black Holes. There are some extremely fascinating things out there in our Universe to explore. In order to travel greater distances into our Universe, and to reach planetary bodies in our Solar System in much less time, new and innovative space propulsion systems must be developed. To this end NASA has created the Prometheus Program. When one considers space missions to the outer edges of our Solar System and far beyond, our Sun cannot be relied on to produce the required spacecraft (s/c) power. Solar energy diminishes as the square of the distance from the Sun. At Mars it is only 43% of that at Earth. At Jupiter, it falls off to only 3.6% of Earth's. By the time we get out to Pluto, solar energy is only .066% what it is on Earth. Therefore, beyond the orbit of Mars, it is not practical to depend on solar power for a s/c. However, the farther out we go the more power we need to heat the s/c and to transmit data back to Earth over the long distances. On Earth, knowledge is power. In the outer Solar System, power is knowledge. It is important that the public be made aware of the tremendous space benefits offered by Nuclear Electric Propulsion (NEP) and the minimal risk it poses to our environment. This paper presents an overview of the reasons for NEP systems, along with their basic components including the reactor, power conversion units (both static and dynamic), electric thrusters, and the launch safety of the NEP system.

Barret, Chris

2003-01-01

391

Synthesis of triple-layered Ag@Co@Ni core-shell nanoparticles for the catalytic dehydrogenation of ammonia borane.  

PubMed

Triple-layered Ag@Co@Ni core-shell nanoparticles (NPs) containing a silver core, a cobalt inner shell, and a nickel outer shell were formed by an in situ chemical reduction method. The thickness of the double shells varied with different cobalt and nickel contents. Ag0.04 @Co0.48 @Ni0.48 showed the most distinct core-shell structure. Compared with its bimetallic core-shell counterparts, this catalyst showed higher catalytic activity for the hydrolysis of NH3 BH3 (AB). The synergetic interaction between Co and Ni in Ag0.04 @Co0.48 @Ni0.48 NPs may play a critical role in the enhanced catalytic activity. Furthermore, cobalt-nickel double shells surrounding the silver core in the special triple-layered core-shell structure provided increasing amounts of active sites on the surface to facilitate the catalytic reaction. These promising catalysts may lead to applications for AB in the field of fuel cells. PMID:24302541

Qiu, Fangyuan; Liu, Guang; Li, Li; Wang, Ying; Xu, Changchang; An, Cuihua; Chen, Chengcheng; Xu, Yanan; Huang, Yanan; Wang, Yijing; Jiao, Lifang; Yuan, Huatang

2014-01-01

392

Experimental Investigation of the Effect of M-Band Preheating in Indirectly-Driven Double-Shell Implosions  

SciTech Connect

Experimental results are presented from several series of experiments studying the effect of 2-4 keV M-shell radiation on the implosion of double-shell capsules on the Omega Laser at the Laboratory for Laser Energetics. In the First series of experiments, precision machined double-shell capsules implosions are performed. A discrepancy is observed between the experimentally measured M-band fraction and the simulated value. The application of a time-dependent multiplier to the simulated M-band level results in a decrease in predicted yield of 35% and a corresponding increase in the YoC to 20-35%. In order to further investigate this discrepancy, a series of ''M-Band driven'' targets has been designed. An oversized outer shell is used to preferentially allow the M-band radiation to drive the implosion of a CH-tamped glass inner shell. The inner shell radius-time history is measured and is shown to be consistent with the simulations using the time-dependent M-band multipliers. The spatial distribution of this M-band source is also varied using hohlraums of different length and adjusting the laser pointing accordingly. The resulting asymmetry of the inner shell implosion is diagnosed both by x-ray backlighting prior to shell collision and by core emission.

Robey, H F; Amendt, P A; Park, H-S; Landen, O L; Watt, R G; Varnum, W S

2003-08-22

393

Elastic stability of cylindrical shells with soft elastic cores: Biomimicking natural tubular structures  

NASA Astrophysics Data System (ADS)

Thin walled cylindrical shell structures are widespread in nature: examples include plant stems, porcupine quills, and hedgehog spines. All have an outer shell of almost fully dense material supported by a low density, cellular core. In nature, all are loaded in combination of axial compression and bending: failure is typically by buckling. Natural structures are often optimized. Here we have analyzed the elastic buckling of a thin cylindrical shell supported by an elastic core to show that this structural configuration achieves significant weight saving over a hollow cylinder. The results of the analysis are compared with data from an extensive experimental program on uniaxial compression and four point bending tests on silicone rubber shells with and without compliant foam cores. The analysis describes the results of the mechanical tests well. Characterization of the microstructures of several natural tubular structures with foamlike cores (plant stems, quills, and spines) revealed them to be close to the optimal configurations predicted by the analytical model. Biomimicking of natural cylindrical shell structures and evolutionary design processes may offer the potential to increase the mechanical efficiency of engineering cylindrical shells.

Karam, Gebran Nizar

1994-01-01

394

Thin Shell Formation Time and [OIII] Line in Fast Wind Bubble  

NASA Astrophysics Data System (ADS)

We determine analytically the onset of thin-shell formation time of fast wind bubble with power-law energy injection E_in = E_0 t^s, and power-law ambient density structure, rho_0(r) = rho(bar)(r/r(bar))^-w. Thin-shell formation time, t_sf can be estimated by minimizing the total time elapsed before the complete cooling of shocked gas. For uniform medium (w = 0) and constant energy injection (s = 1), the onset of shell formation is found to be at t_sf = 5.2x10e3 yr, which agrees quite well with the results of FCT 1D numerical calculation. We solve the line transfer problem with previous result derived by numerical calculation in order to calculate line profile of [OIII] (lambda= 5007 A) forbidden line. In general, radiative outer shell causes the formation of double peaked line profile. Each peak corresponds to approaching and receding shells with large velocities. Our line profiles show good agreements with observation of expanding shell structure.

Choe, Seung-Urn; Lee, Yeong-Jin

1996-12-01

395

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

396

A Multi-Shell Shell Model For Heavy Nuclei  

NASA Astrophysics Data System (ADS)

The difficulty of performing a shell model calculation for heavy nuclei has been a long-standing problem in nuclear physics. Because of this, the study of nuclear structure in heavy nuclei has relied mainly on the mean field approximations. However, the necessity of the proper quantum mechanical treatment of nuclear states has been growing, and we are now facing the challenge of understanding the nuclear structure problems in many exotic systems that are important for nuclear astrophysics. Great effort has been devoted to developing a shell model for heavy nuclear system, but still there is a long way to go. The current large-scale shell model diagonalization can be best applied only up to the full pf-shell space. We propose a multi-shell shell model for heavy nuclei. The central idea of this proposal is to take the advantages of two existing models: the Projected Shell Model (PSM) [1] and the Fermion Dynamical Symmetry Model (FDSM) [2]. The PSM treats successfully the quasi-particle excitations and their coupling to the rotational motion, whereas the FDSM handles efficiently various low-spin collective excitation modes from the spherical to the well-deformed region. The new model that we suggest is able to describe simultaneously the single-particle and the collective excitations, yet keeping the model space tractable even for the heaviest system. [1] K. Hara and Y. Sun, Int. J. Mod. Phys. E4, 637 (1995). [2] C.-L. Wu, M. Guidry and D.H. Feng, Adv. Nucl. Phys. 21, 227 (1994).

Sun, Yang; Wu, Cheng-Li

2002-10-01

397

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

398

Carbon isotopes in mollusk shell carbonates  

Microsoft Academic Search

Mollusk shells contain many isotopic clues about calcification physiology and environmental conditions at the time of shell\\u000a formation. In this review, we use both published and unpublished data to discuss carbon isotopes in both bivalve and gastropod\\u000a shell carbonates. Land snails construct their shells mainly from respired CO2, and shell ?13C reflects the local mix of C3 and C4 plants

Ted A. McConnaughey; David Paul Gillikin

2008-01-01

399

Artificially soft and hard surfaces in electromagnetics  

Microsoft Academic Search

A transversely corrugated surface as used in corrugated horn antennas represents a soft boundary. A hard boundary is made by using longitudinal corrugations filled with dielectric material. The concept of soft and hard surfaces is treated in detail, considering different geometries. It is shown that both the hard and soft boundaries have the advantage of a polarization-independent reflection coefficient for

Per-Simon Kildal

1990-01-01

400

Model of hard spheroplatelets near a hard wall  

NASA Astrophysics Data System (ADS)

A system of hard spheroplatelets near an impenetrable wall is studied in the low-density Onsager approximation. Spheroplatelets have optimal shape between rods and plates, and the direct transition from the isotropic to biaxial nematic phase is present. A simple local approximation for the one-particle distribution function is used. Analytical results for the surface tension and the entropy contributions are derived. The density and the order-parameter profiles near the wall are calculated. The preferred orientation of the short molecule axes is perpendicular to the wall. Biaxiality close to the wall can appear only if the phase is biaxial in the bulk.

Kapanowski, A.; Abram, M.

2014-06-01

401

Controlled synthesis and magnetic properties of bimagnetic spinel ferrite CoFe2O4 and MnFe2O4 nanocrystals with core-shell architecture.  

PubMed

A combination of hard phase CoFe(2)O(4) and soft phase MnFe(2)O(4) as the bimagnetic nanocrystals in a core-shell architecture has been synthesized, and their magnetic properties have been systematically studied. Both HRTEM and EDS results confirmed the formation of bimagnetic core-shell structured nanocrystals. On the basis of the systematic and comparative studies of the magnetic properties of a mechanical mixture of pure CoFe(2)O(4) and MnFe(2)O(4) nanocrystals, chemically mixed Co(1-x)Mn(x)Fe(2)O(4) nanocrystals, and bimagnetic core-shell CoFe(2)O(4)@MnFe(2)O(4) and MnFe(2)O(4)@CoFe(2)O(4) nanocrystals, the bimagnetic core-shell nanocrystals show very unique magnetic properties, such as the blocking temperature and coercivity. Our results show that the coercivity correlates with the volume fraction of the soft phase as the theoretical hard-soft phase model has suggested. Furthermore, switching the hard phase CoFe(2)O(4) from the core to the shell shows great changes in the coercivity of the nanocrystals. The bimagnetic core-shell nanocrystals evidently demonstrate the rational design capability to separately control the blocking temperature and the coercivity in magnetic nanocrystals by varying the materials, their combination, and the volume ratio between the core and the shell and by switching hard or soft phase materials between the core and shell. Such controls via a bimagnetic core-shell architecture are highly desirable for magnetic nanocrystals in various applications. PMID:22621435

Song, Qing; Zhang, Z John

2012-06-20

402

Fault tolerant, radiation hard, high performance digital signal processor  

NASA Technical Reports Server (NTRS)

An architecture has been developed for a high-performance VLSI digital signal processor that is highly reliable, fault-tolerant, and radiation-hard. The signal processor, part of a spacecraft receiver designed to support uplink radio science experiments at the outer planets, organizes the connections between redundant arithmetic resources, register files, and memory through a shuffle exchange communication network. The configuration of the network and the state of the processor resources are all under microprogram control, which both maps the resources according to algorithmic needs and reconfigures the processing should a failure occur. In addition, the microprogram is reloadable through the uplink to accommodate changes in the science objectives throughout the course of the mission. The processor will be implemented with silicon compiler tools, and its design will be verified through silicon compilation simulation at all levels from the resources to full functionality. By blending reconfiguration with redundancy the processor implementation is fault-tolerant and reliable, and possesses the long expected lifetime needed for a spacecraft mission to the outer planets.

Holmann, Edgar; Linscott, Ivan R.; Maurer, Michael J.; Tyler, G. L.; Libby, Vibeke

1990-01-01

403

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

404

Shell layer variation in trace element concentration for the freshwater bivalve Elliptio complanata  

NASA Astrophysics Data System (ADS)

While the elemental chemistry of marine mollusk shells contains valuable environmental information, extending these interpretations to freshwater bivalve shells may be problematic, given the wide range of aqueous chemistries that exist in freshwater environments. To better understand the significance of these records, 20 bivalves were collected from four freshwater streams to determine the geochemical relationships that exist between the bivalve shell and their sources streams. The concentrations of manganese (Mn), copper (Cu), strontium (Sr), barium (Ba), and calcium (Ca) were analyzed by laser ablation inductively coupled plasma mass spectrometry across the inner (INL) and outer nacreous layer (ONL) of each shell for comparison to stream data collected over the period of shell growth. Within an individual shell, the content of Mn, Sr, and Ba were significantly higher in the INL than the ONL, while Cu concentrations were similar. Strontium and Ba concentrations co-varied between the two layers in 1:1 relationships, while Mn displayed a preferential enrichment in the INL that increased from 2:1 to 5:1 as the Mn content of the shell decreased. Each elemental profile can be correlated between shell layers, except for the trace element Cu, which appeared to be more closely related to the organic content of the shell. These results suggest that the major element geochemistry of the shell layers differentially reflect the aqueous chemistry of the water in which a bivalve lived, but that these records are most likely overprinted by physiological processes specific to the mantle tissue from which a particular shell layer is secreted. Distribution coefficients (shell M /Ca:water M /Ca, where M = trace element of interest) were calculated using the median molar elemental concentration for each shell (by layer), and the appropriate water concentration. Bivalves from a contaminated site were excluded from this analysis because their shells were anomalous in size and color. For the remaining 15 shells, distribution coefficients (INL and ONL) were: Mn (0.50 and 0.21), Sr (0.26 and 0.17), and Ba (0.05: INL only). Inner nacreous layer values were comparable to the upper end of published estimates for freshwater bivalves and fish otoliths, while the ONL values were comparable to the lower range of values. Inclusion of shells from the contaminated site resulted in the calculation of distribution coefficients that fell outside the range of published estimates. These results suggest that exposure to pollutants may have a bearing on the biological factors that control the elemental concentration of bivalve shells in freshwater environments. While researchers generally avoid sampling shell material from the INL because of the potential for shell dissolution, the similarity in elemental profile trends observed here suggests that both the INL and ONL record accurate geochemical information, but in distinct forms. An obvious advantage of INL analysis is the relative increase in elemental concentration, but this is afforded at the expense of spatial resolution. Considered collectively, these results suggest that valuable information can be gleaned from the elemental concentration of freshwater bivalve shells when care is taken in the choice of material from which these records are extracted.

Carroll, Monica; Romanek, Christopher S.

2008-10-01

405

Simulating the Outer Radiation Belt During the Rising Phase of Solar Cycle 24  

NASA Technical Reports Server (NTRS)

After prolonged period of solar minimum, there has been an increase in solar activity and its terrestrial consequences. We are in the midst of the rising phase of solar cycle 24, which began in January 2008. During the initial portion of the cycle, moderate geomagnetic storms occurred follow the 27 day solar rotation. Most of the storms were accompanied by increases in electron fluxes in the outer radiation belt. These enhancements were often preceded with rapid dropout at high L shells. We seek to understand the similarities and differences in radiation belt behavior during the active times observed during the of this solar cycle. This study includes extensive data and simulations our Radiation Belt Environment Model. We identify the processes, transport and wave-particle interactions, that are responsible for the flux dropout and the enhancement and recovery.

Fok, Mei-Ching; Glocer, Alex; Zheng, Qiuhua; Chen, Sheng-Hsien; Kanekal, Shri; Nagai, Tsungunobu; Albert, Jay

2011-01-01

406

Proton-proton bremsstrahlung: Consequences of different on-shell-point conditions  

SciTech Connect

Background: Proton-proton bremsstrahlung (pp{gamma}) is investigated both theoretically and experimentally. The pp{gamma} amplitudes can be classified according to the number and location of on-shell points at which they are evaluated. Quantitative understanding of the effect on the pp{gamma} cross section of using different on-shell-point conditions is lacking, but it is essential to identifying the photon emission mechanism governing the pp{gamma} process. Method: Four different pp{gamma} amplitudes, which include four-on-shell-point amplitudes and one-on-shell-point amplitude, are generated from a realistic one-boson-exchange (ROBE) model for pp scattering. These ROBE amplitudes are used to investigate the consequence of using different on-shell-point conditions in calculating the pp{gamma} cross sections. Purpose: We verify the validity of the ROBE pp{gamma} amplitudes. We explore similarities between the four-on-shell-point ROBE and two-u-two-t special (TuTts) soft-photon pp{gamma} amplitudes and important differences with the one-on-shell-point ROBE and Low pp{gamma} amplitudes. We demonstrate that the precision Kernfysisch Versneller Instituut (KVI) data can only be described by the four-on-shell-point (ROBE or TuTts) amplitude. We use the ROBE four-on-shell-point amplitude and one-on-shell-point amplitude to investigate systematically the effect of using different on-shell-point conditions to calculate the pp{gamma} cross section. Furthermore, we identify a general principle that governs the process. This general principle is also applicable to other bremsstrahlung processes involving the scattering of two identical nucleons. Results: (i) The four-on-shell-point ROBE (or TuTts) amplitude describes the high-precision KVI data much better than does the one-on-shell-point ROBE (or Low) amplitude. Although the contribution from the anomalous magnetic moment of the proton is very significant, it does not completely dominate the KVI pp{gamma} cross sections. (ii) The four-on-shell-point ROBE (or TuTts) amplitude describes the TRIUMF data better than does the one-on-shell-point ROBE (or Low) amplitude. (iii) The effect on the pp{gamma} cross section of using different on-shell-point conditions is significant in the hard-photon region, i.e., for small proton scattering angles {theta} (={theta}{sub 3}={theta}{sub 4}, symmetric scattering angles) far from the elastic limit ({theta}{yields}45 deg.); in contrast, the effect becomes insignificant in the vicinity of the elastic limit. Near the limit as {theta} tends to 45 deg. (or as the photon energy K approaches zero), the four-on-shell-point and one-on-shell-point amplitudes approach one another, a general principle applicable to all bremsstrahlung processes because only kinematics is involved. Conclusion: The four-on-shell-point ROBE amplitude provides a quantitative description of pp{gamma} cross sections. The anomalous magnetic moment is an important component of the photon emission mechanism. The four-on-shell-point property of the full ROBE amplitude is essential to properly describing the complete range of the precision KVI data and the TRIUMF data, although the one-on-shell-point ROBE amplitude is adequate in the region near the elastic limit.

Li, Yi; Liou, M. K.; Schreiber, W. M.; Gibson, B. F. [College of Physics and Technology, Guangxi University, Nanning, Guangxi 530004 (China); Department of Physics and Institute for Nuclear Theory, Brooklyn College of the City University of New York, Brooklyn, New York 11210 (United States); Department of Physics, College of Staten Island of the City University of New York, Staten Island, New York 10314 (United States); Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2011-09-15

407

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

2009-03-23

408

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

409

Tectonics of the Outer Planet Satellites  

NASA Technical Reports Server (NTRS)

Tectonic features on the satellites of the outer planets range from the familiar, such as clearly recognizable graben on many satellites, to the bizarre, such as the ubiquitous double ridges on Europa, the twisting sets of ridges on Triton, or the isolated giant mountains rising from Io's surface. All of the large and middle-sized outer planet satellites except Io are dominated by water ice near their surfaces. Though ice is a brittle material at the cold temperatures found in the outer solar system, the amount of energy it takes to bring it close to its melting point is lower than for a rocky body. Therefore, some unique features of icy satellite tectonics may be influenced by a near-surface ductile layer beneath the brittle surface material, and several of the icy satellites may possess subsurface oceans. Sources of stress to drive tectonism are commonly dominated by the tides that deform these satellites as they orbit their primary giant planets. On several satellites, the observed tectonic features may be the result of changes in their tidal figures, or motions of their solid surfaces with respect to their tidal figures. Other driving mechanisms for tectonics include volume changes due to ice or water phase changes in the interior, thermoelastic stress, deformation of the surface above rising diapirs of warm ice, and motion of subsurface material toward large impact basins as they fill in and relax. Most satellites exhibit evidence for extensional deformation, and some exhibit strike-slip faulting, whereas contractional tectonism appears to be rare. Io s surface is unique, exhibiting huge isolated mountains that may be blocks of crust tilting and foundering into the rapidly emptying interior as the surface is constantly buried by deposits from hyperactive volcanoes. Of the satellites, diminutive Enceladus is spectacularly active; its south polar terrain is a site of young tectonism, copious heat flow, and tall plumes venting into space. Europa's surface is pervasively tectonized, covered with a diverse array of exotic and incompletely understood tectonic features. The paucity of impact craters on Europa suggests that its tectonic activity is ongoing. Geysers on Triton show that some degree of current activity, while tectonic features that cross sparsely cratered terrain indicate that it may also be tectonically active. Ganymede and Miranda both exhibit ancient terrains that have been pulled apart by normal faulting. On Ganymede these faults form a global network, while they are confined to regional provinces on Miranda. Ariel, Dione, Tethys, Rhea, and Titania all have systems of normal faults cutting across their surfaces, though the rifting is less pronounced than it is on Ganymede and Miranda. Iapetus exhibits a giant equatorial ridge that has defied simple explanation. The rest of the large and middle-sized satellites show very little evidence for tectonic features on their surfaces, though the exploration of Titan's surface has just begun.

McKinnon, W. B.; Collins, G. C.; Moore, J. M.; Nimmo, F.; Pappalardo, R. T.; Prockter, L. M.; Schenk, P. M.

2010-01-01

410

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

411

Europa's Icy Shell: A Bridge Between Its Surface and Ocean  

NASA Technical Reports Server (NTRS)

Europa, a Moon-sized, ice-covered satellite of Jupiter, is second only to Mars in its astrobiological potential. Beneath the icy surface, an ocean up to 150 km deep is thought to exist, providing a potential habitat for life,and a tempting target for future space missions. The Galileo mission to the Jovian system recently ended, but there are already long-range plans to send much more capable spacecraft,such as the proposed Jupiter Icy Moons Orbiter (JIMO), to take a closer look at Europa and her siblings, Ganymede and Callisto, some time in the next two decades. Europak outer icy shell is the only interface between this putative ocean and the surface, but many aspects of this shell are presently poorly understood; in particular, its composition, thickness, deformational history, and mechanical properties. To discuss the ice shell and our current understanding of it, 78 scientists from the terrestrial and planetary science communities in the United States and Europe gathered for a 3-day workshop hosted by the Lunar and Planetary Institute in Houston in February. A key goal was to bring researchers from disparate disciplines together to discuss the importance and limitations of available data on Europa with a post-Galileo perspective. The workshop featured 2 days of reviews and contributed talks on the composition, physical properties, stratigraphy, tectonics, and future exploration of the ice shell and underlying ocean. The final morning included an extended discussion period, moderated by a panel of noted experts, highlighting outstanding questions and areas requiring future research.

Schenk, Paul; Mimmo, Francis; Prockter, Louise

2004-01-01

412

SN 1994W: an interacting supernova or two interacting shells?  

NASA Astrophysics Data System (ADS)

We present a multi-epoch quantitative spectroscopic analysis of the Type IIn supernova (Type IIn SN) 1994W, an event interpreted by Chugai et al. as stemming from the interaction between the ejecta of a SN and a 0.4Msolar circumstellar shell ejected 1.5yr before core collapse. During the brightening phase, our models suggest that the source of optical radiation is not unique, perhaps associated with an inner optically thick cold dense shell and outer optically thin shocked material. During the fading phase, our models support a single source of radiation, an hydrogen-rich optically thick layer with a near-constant temperature of ~7000K that recedes from a radius of 4.3 × 1015 at a peak to 2.3 × 1015cm 40 d later. We reproduce the hybrid narrow-core broad-wing line profile shapes of SN 1994W at all times, invoking an optically thick photosphere exclusively (i.e. without any external optically thick shell). In SN 1994W, slow expansion makes scattering with thermal electrons a key escape mechanism for photons trapped in optically thick line cores, and allows the resulting broad incoherent electron-scattering wings to be seen around narrow-line cores. In SNe with larger expansion velocities, the thermal broadening due to incoherent scattering is masked by the broad profile and the dominant frequency redshift occasioned by bulk motions. Given the absence of broad lines at all times and the very low 56Ni yields, we speculate whether SN 1994W could have resulted from an interaction between two ejected shells without core collapse. The high conversion efficiency of kinetic to thermal energy may not require a SN-like energy budget for SN1994W.

Dessart, Luc; Hillier, D. John; Gezari, Suvi; Basa, Stéphane; Matheson, Tom

2009-03-01

413

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

414

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

415

76 FR 67759 - Notice on Outer Continental Shelf Oil and Gas Lease Sales  

Federal Register 2010, 2011, 2012, 2013

...Corporation ExxonMobil Exploration Company Group II Shell Oil Company Shell Offshore Inc. SWEPI LP Shell Frontier Oil & Gas Inc. SOI Finance Inc. Shell Gulf of Mexico Inc. Group III BP America Production Company BP Exploration & Production Inc. BP...

2011-11-02

416

77 FR 24980 - Notice on Outer Continental Shelf Oil and Gas Lease Sales  

Federal Register 2010, 2011, 2012, 2013

...Corporation ExxonMobil Exploration Company Group II. Shell Oil Company Shell Offshore Inc. SWEPI LP Shell Frontier Oil & Gas Inc. SOI Finance Inc. Shell Gulf of Mexico Inc. Group III. BP America Production Company BP Exploration & Production Inc. BP...

2012-04-26

417

76 FR 28449 - Notice on Outer Continental Shelf Oil and Gas Lease Sales  

Federal Register 2010, 2011, 2012, 2013

...ExxonMobil Exploration Company. Group II. Shell Oil Company, Shell Offshore Inc., SWEPI LP, Shell Frontier Oil & Gas Inc., SOI Finance Inc., Shell Gulf of Mexico Inc. Group III. BP America Production Company, BP Exploration & Production Inc.,...

2011-05-17

418

77 FR 64826 - Notice on Outer Continental Shelf Oil and Gas Lease Sales  

Federal Register 2010, 2011, 2012, 2013

...Corporation ExxonMobil Exploration Company Group II. Shell Oil Company Shell Offshore Inc. SWEPI LP Shell Frontier Oil & Gas Inc. SOI Finance Inc. Shell Gulf of Mexico Inc. Group III. BP America Production Company BP Exploration & Production Inc. BP...

2012-10-23

419

Making Nozzles From Hard Materials  

NASA Technical Reports Server (NTRS)

Proposed method of electrical-discharge machining (EDM) cuts hard materials like silicon carbide into smoothly contoured parts. Concept developed for fabrication of interior and exterior surfaces and internal cooling channels of convergent/divergent nozzles. EDM wire at skew angle theta creates hyperboloidal cavity in tube. Wire offset from axis of tube and from axis of rotation by distance equal to throat radius. Maintaining same skew angle as that used to cut hyperboloidal inner surface but using larger offset, cooling channel cut in material near inner hyperboloidal surface.

Wells, Dennis L.

1989-01-01

420

Dissolution testing of soft shell capsules-acetaminophen and nifedipine.  

PubMed

The problem of pelliculation of soft gelatin capsules on aging has been studied. Pelliculation frequently differs in soft shell capsules from hard shell capsules because of the larger mass of gelatin in the softshell dosage form. Two batches of nifedipine soft shell capsules are described. One batch failed in vivo testing and the other batch did not, after storage at 25 degrees C, yet both batches failed dissolution testing by the USP apparatus II method. The USP dissolution apparatus III-method, however, distinguished correctly between the batches. The study reported here was carried out with acetaminophen and was set up to establish whether the USP apparatus III testing method would be more suitable, and if so, what the most desirable dissolution medium should be. To create controlled pelliculation, samples were made with 0, 20, and 80 ppm of formaldehyde. The resulting capsules were subjected to ambient and accelerated storage and dissolution testing was carried out. It was found that the USP apparatus III method best reflected distinction between acceptable and substandard capsules. PMID:9294822

Bottom, C B; Clark, M; Carstensen, J T

1997-09-01

421

Semiclassical environment of collapsing shells  

SciTech Connect

We explore in detail the semiclassical environment of collapsing shells of matter, and determine the semiclassical flux measured by a variety of observers. This study is a preliminary step in a broader investigation of thermodynamic properties of the geometry of collapsing objects. Specifically, in this paper we consider spherically symmetric null and timelike collapsing shells which form an event horizon, and calculate the flux measured by observers both inside and outside the shell, and both inside and outside the event horizon, and find nontrivial results in most of the cases. Additionally, we also investigate the environment of a shell which collapses but does not form a horizon, halting at some radius larger than the Schwarzschild radius, and find that such an object generically gives rise to a pulse of radiation which is sharply peaked as it travels inwards and is reflected at the origin, and eventually emerges from the shell in a thermalized form. Our results have potential consequences in addressing questions pertaining, e.g. to black hole entropy and backreaction.

Banerjee, Kinjal; Paranjape, Aseem [IUCAA, Post Bag 4, Ganeshkhind, Pune-411 007 (India); Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400 005 (India)

2009-12-15

422

Foam shell project: Progress report  

SciTech Connect

The authors report on their work to produce a foam shell target for two possible applications: (1) as liquid-layered cryogenic target on Omega Upgrade, and (2) as a back-up design for the NIF. This target consists of a roughly 1 mm diameter and 100 {mu}m thick spherical low-density foam shell surrounding a central void. The foam will be slightly overfilled with liquid D{sub 2} or DT, the overfilled excess being symmetrically distributed on the inside of the shell and supported by thermal gradient techniques. The outside of the foam is overcoated with full density polymer which must be topologically smooth. The technology for manufacturing this style of foam shell involves microencapsulation techniques and has been developed by the Japanese at ILE. Their goal is to determine whether this technology can be successfully adapted to meet US ICF objectives. To this end a program of foam shell development has been initiated at LLNL in collaboration with both the General Atomics DOE Target Fabrication Contract Corporation and the Target Fabrication Group at LLE.

Overturf, G.; Reibold, B.; Cook, B. [Lawrence Livermore National Lab., CA (United States); Schroen-Carey, D. [WJSA (United States)

1994-03-25

423

Infrared observations of outer planet satellites  

NASA Astrophysics Data System (ADS)

This task supports IR observations of the outer planet satellites. These data provide vital information about the thermophysical properties of satellite surfaces, including internal heat sources for Io. Observations include both broad and narrow band measurementsin the 2 to 20 micrometer spectral range. The program in the last year has aimed at obtaining lonitude coverage on Io to establish stability of hot spot patterns previously reported. Several runs produced the most complete data set for an apparition since the start of the program. Unfortunately, bad weather limited coverage of key longitude ranges containing the largest known hot spot Loki. Among the preliminary results is the observation of an outburst in Io's thermal flux that was measured at 4.8, 8.7 and 20 micrometer. Analysis of the data has given the best evidence to date of silicate volcanism on Io; this is one of the most significant pieces of the puzzle as to the relative roles of silicate and sulfur volcanism on Io. Researchers are collaborating with J. Goguen (NRC RRA to finish reduction of mutual event data, which have already improved ephermeris information for the satellites. The data appear to place significant limits on the characteristics of any leading side hot spots.

Johnson, T. V.

1988-08-01

424

Infrared observations of outer planet satellites  

NASA Technical Reports Server (NTRS)

This task supports IR observations of the outer planet satellites. These data provide vital information about the thermophysical properties of satellite surfaces, including internal heat sources for Io. Observations include both broad and narrow band measurementsin the 2 to 20 micrometer spectral range. The program in the last year has aimed at obtaining lonitude coverage on Io to establish stability of hot spot patterns previously reported. Several runs produced the most complete data set for an apparition since the start of the program. Unfortunately, bad weather limited coverage of key longitude ranges containing the largest known hot spot Loki. Among the preliminary results is the observation of an outburst in Io's thermal flux that was measured at 4.8, 8.7 and 20 micrometer. Analysis of the data has given the best evidence to date of silicate volcanism on Io; this is one of the most significant pieces of the puzzle as to the relative roles of silicate and sulfur volcanism on Io. Researchers are collaborating with J. Goguen (NRC RRA to finish reduction of mutual event data, which have already improved ephermeris information for the satellites. The data appear to place significant limits on the characteristics of any leading side hot spots.

Johnson, T. V.

1988-01-01

425

Magnetic Field in the Outer Heliosphere  

NASA Technical Reports Server (NTRS)

Observed properties of the magnetic field in the outer heliosphere are generally well described by the Parker model but evidence has accumulated of significant departures in the components and field magnitude. The radial component is independent of solar latitude at both solar minimum and maximum implying non-radial solar wind flow near the Sun driven by differential magnetic pressure. The azimuthal component deviates from the Parker values at high latitudes as a result of the non-radial flow near the Sun that causes fields to originate at higher latitudes than those at which they are observed far from the Sun. A turning of the spiral angle toward the radial direction by tens of degrees is often observed inside co-rotating rarefaction regions (dwells). A recent model attributes this effect to a motion of the field across polar coronal hole boundaries that results in different solar wind speeds along parts of the field line. The north-south component can depart from zero for many days as a result of the tilting of the interface between fast and slow streams. Recent Voyager observations show that, during solar minimum, the field magnitude is smaller than extrapolations outward from 1 AU. This 'flux deficit,' seen earlier in Pioneer data, may be explained by any of several physical models.

Smith, Edward J.

2004-01-01

426

Bacterial Outer Membrane Vesicles and Vaccine Applications  

PubMed Central

Vaccines based on outer membrane vesicles (OMV) were developed more than 20?years ago against Neisseria meningitidis serogroup B. These nano-sized structures exhibit remarkable potential for immunomodulation of immune responses and delivery of meningococcal antigens or unrelated antigens incorporated into the vesicle structure. This paper reviews different applications in OMV Research and Development (R&D) and provides examples of OMV developed and evaluated at the Finlay Institute in Cuba. A Good Manufacturing Practice (GMP) process was developed at the Finlay Institute to produce OMV from N. meningitidis serogroup B (dOMVB) using detergent extraction. Subsequently, OMV from N. meningitidis, serogroup A (dOMVA), serogroup W (dOMVW), and serogroup X (dOMVX) were obtained using this process. More recently, the extraction process has also been applied effectively for obtaining OMV on a research scale from Vibrio cholerae (dOMVC), Bordetella pertussis (dOMVBP), Mycobacterium smegmatis (dOMVSM), and BCG (dOMVBCG). The immunogenicity of the OMV has been evaluated for specific antibody induction, and together with functional bactericidal and challenge assays in mice has shown their protective potential. dOMVB has been evaluated with non-neisserial antigens, including with a herpes virus type 2 glycoprotein, ovalbumin, and allergens. In conclusion, OMV are proving to be more versatile than first conceived and remain an important technology for development of vaccine candidates.

Acevedo, Reinaldo; Fernandez, Sonsire; Zayas, Caridad; Acosta, Armando; Sarmiento, Maria Elena; Ferro, Valerie A.; Rosenqvist, Einar; Campa, Concepcion; Cardoso, Daniel; Garcia, Luis; Perez, Jose Luis

2014-01-01

427

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

428

THE OUTER MAGNETIC FIELD OF L183  

SciTech Connect

The L183 (= L134N) dark molecular cloud has been probed using deep near-infrared imaging polarimetry of stars to beyond 14 mag in H band (1.6 {mu}m), using the Mimir instrument on the 1.83 m Perkins Telescope. Nearly 400 arcmin{sup 2} were surveyed, including the dense core in L183, as seen in WISE Band 3 (12 {mu}m) extinction, and the near surroundings, revealing 35 stars with either detected polarizations or significant upper limits. Stars with detected polarizations are reddened if closer than 8 arcmin (0.25 pc at the 110 pc cloud distance) and unreddened beyond. The polarimetric sample probes as close to the core as 3 arcmin (0.1 pc), where A{sub V} {approx} 14 mag. Compared to the relatively unextincted surrounding stars, the reddened stars show no increase in polarization with extinction, suggesting that all of the polarization is induced in the outer layers of the cloud. This 0.25 pc radius envelope magnetic field does show a strong interaction with the L183 dark cloud. The envelope field is also virtually perpendicular, on the plane of the sky, to the field seen at 850 {mu}m, though more closely aligned with the rotation axis of the dense gas core. The physical size scale at which the envelope and the core magnetic fields either decouple from each other or strongly modify their directions must be inside the 0.1 pc region probed here.

Clemens, Dan P., E-mail: clemens@bu.edu [Institute for Astrophysical Research, Boston University, 725 Commonwealth Ave, Boston, MA 02215 (United States)

2012-03-20

429

Dominant thermogravimetric signatures of lignin in cashew shell as compared to cashew shell cake.  

PubMed

Dominant thermogravimetric signatures related to lignin were observed in cashew shell as compared to these signatures in cashew shell cake. The phenomenon of weakening of lignin from cashew shell to cashew shell cake was explained on the basis of changes in the activation energies. The pertinent temperature regimes responsible for the release of different constituents of both the bio-materials were identified and compared. The activation energies of cashew shell and cashew shell cake were compared using Kissinger-Akahira-Sunose method. Thermogravimetric profiling of cashew shell and cashew shell cake indicated that these were different kinds of bio-materials. PMID:24412920

Gangil, Sandip

2014-03-01

430

Preparation of alumina/silica core-shell abrasives and their CMP behavior  

NASA Astrophysics Data System (ADS)

Abrasive is one of key influencing factors on the surface quality during the chemical mechanic polishing (CMP). ?-Alumina particles, as a kind of widely used abrasive in CMP slurries, often cause to surface defects because of its high hardness. In the present paper, a series of novel alumina/silica core-shell abrasives in slurries were described. The CMP performances of the alumina/silica core-shell abrasives on hard disk substrate were investigated by using a SPEEDFAM-16B-4M CMP equipment. Experimental results indicate that the CMP performances a