Science.gov

Sample records for hard outer shell

  1. Intershell correlations in photoionization of outer shells

    NASA Astrophysics Data System (ADS)

    Amusia, M. Ya.; Chernysheva, L. V.; Drukarev, E. G.

    2016-02-01

    We demonstrate that the cross sections for photoionization of the outer shells are noticeably modified at the photon energies close to the thresholds of ionization of the inner shells due to correlations with the latter. The correlations may lead to increase or to decrease of the cross sections just above the ionization thresholds.

  2. Outer shell, inner blocklets, and granule architecture of potato starch.

    PubMed

    Huang, Junrong; Wei, Ningguo; Li, Hongliang; Liu, Shuxing; Yang, Daqing

    2014-03-15

    Potato starch was heated in distilled water and acetic acid solution (pH = 1.5), respectively, then washed with anhydrous ethanol and dried. After cooked in water with certain program, high-resolution scanning electron micrographs (SEM) of broken granules showed isolated outer shells. After treatment with acetic acid, SEM images of dissilient granules exhibited outer shells with randomly assembled spherical inner blocklets. A refined blocklet model was proposed for potato starch granule, the smaller blocklets were compacted densely to form the stiffer outer shell, and the larger blocklets were packed loosely to form the inner shells. PMID:24528740

  3. The hard sphere view of the outer core

    NASA Astrophysics Data System (ADS)

    Helffrich, George

    2015-12-01

    The hard sphere model for liquids attempts to capture the physical behavior of a real liquid in a simple conceptual model: a fluid of fixed size spheres that only interact repulsively when they come into contact. Is the model good enough to use for modeling internal planetary structure? To answer this question, I survey variants of hard sphere liquid theory by applying them to the Earth's outer core to determine which of them explains wavespeeds in the outer core best. The variants explored here are the Carnahan-Starling hard sphere model, the Mansoori-Canfield extension to hard sphere mixtures, the transition metal hard sphere liquid, and the Lennard-Jones hard sphere liquid with attractive forces. With an empirical addition of a temperature dependence to the liquid's hard sphere diameter, all of the variants explored can replicate wavespeeds in most of the radius range of the outer core. The hard sphere model for liquid transition metals explains the wavespeed best because it yields a mean liquid atomic weight of 48.8 g mo l -1 at 10 wt% light element abundance in the core which is in good cosmochemical agreement with core light element models. Other variants also fit core wavespeeds but require implausibly low liquid mean atomic weight implying excessive incorporation of hydrogen or helium in the core. Applied to the detailed wavespeed structure of the Earth's outermost outer core, the model suggests that the mean atomic weight could be reduced by up to 1.74% or the temperature could be increased by up to 400 K relative to an adiabatic profile, or there could be 8% fewer valence electrons in the liquid.

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

    DOEpatents

    Leach, David; Bergendahl, Peter Allen; Waldo, Stuart Forrest; Smith, Robert Leroy; Phelps, Robert Kim

    2001-01-01

    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.

  5. Elasticity of interfacial rafts of hard particles with soft shells.

    PubMed

    Knoche, Sebastian; Kierfeld, Jan

    2015-05-19

    We study an elasticity model for compressed protein monolayers or particle rafts at a liquid interface. Based on the microscopic view of hard-core particles with soft shells, a bead-spring model is formulated and analyzed in terms of continuum elasticity theory. The theory can be applied, for example, to hydrophobin-coated air-water interfaces or, more generally, to liquid interfaces coated with an adsorbed monolayer of interacting hard-core particles. We derive constitutive relations for such particle rafts and describe the buckling of compressed planar liquid interfaces as well as their apparent Poisson ratio. We also use the constitutive relations to obtain shape equations for pendant or buoyant capsules attached to a capillary, and to compute deflated shapes of such capsules. A comparison with capsules obeying the usual Hookean elasticity (without hard cores) reveals that the hard cores trigger capsule wrinkling. Furthermore, it is shown that a shape analysis of deflated capsules with hard-core/soft-shell elasticity gives apparent elastic moduli which can be much higher than the original values if Hookean elasticity is assumed. PMID:25901364

  6. Correlation of HI shells and CO clumps in the outer Milky Way

    NASA Astrophysics Data System (ADS)

    Ehlerová, S.; Palouš, J.

    2016-03-01

    Context. HI shells, which may be formed by the activity of young and massive stars, or connected to energy released by interactions of high-velocity clouds with the galactic disk, may be partly responsible both for the destruction of CO clouds and for the creation of others. It is not known which effect prevails. Aims: We study the relation between HI shells and CO in the outer parts of the Milky Way, using HI and CO surveys and a catalogue of previously identified HI shells. Methods: For each individual location, the distance to the nearest HI shell is calculated and it is specified whether it lies in the interior of an HI shell, in its walls, or outside an HI shell. The method takes into account irregular shapes of HI shells. Results: We find a lack of CO clouds in the interiors of HI shells and their increased occurrence in walls. Properties of clouds differ for different environments: interiors of HI shells, their walls, and unperturbed medium. Conclusions: CO clouds found in the interiors of HI shells are those that survived and were robbed of their more diffuse gas. Walls of HI shells have a high molecular content, indicative of an increased rate of CO formation. Comparing the CO fractions within HI shells and outside in the unperturbed medium, we conclude that HI shells are responsible for a ~20% increase in the total amount of CO in the outer Milky Way.

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

    SciTech Connect

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

    2013-09-10

    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.

  8. 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, 2014

    2012-05-08

    ... AGENCY Notice of Approval of Clean Air Act Outer Continental Shelf Permits Issued to Shell Offshore, Inc... Title V air quality operating permit to Shell Offshore, Inc. (``Shell'') for operation of the Kulluk... March 30, 2012, the EAB issued an order denying review of all three petitions. See In re Shell...

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

    SciTech Connect

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

    2014-06-14

    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.

  10. Driven self-assembly of hard nanoplates on soft elastic shells

    NASA Astrophysics Data System (ADS)

    Zhang, Yao-Yang; Hua, Yun-Feng; Deng, Zhen-Yu

    2015-11-01

    The driven self-assembly behaviors of hard nanoplates on soft elastic shells are investigated by using molecular dynamics (MD) simulation method, and the driven self-assembly structures of adsorbed hard nanoplates depend on the shape of hard nanoplates and the bending energy of soft elastic shells. Three main structures for adsorbed hard nanoplates, including the ordered aggregation structures of hard nanoplates for elastic shells with a moderate bending energy, the collapsed structures for elastic shells with a low bending energy, and the disordered aggregation structures for hard shells, are observed. The self-assembly process of adsorbed hard nanoplates is driven by the surface tension of the elastic shell, and the shape of driven self-assembly structures is determined on the basis of the minimization of the second moment of mass distribution. Meanwhile, the deformations of elastic shells can be controlled by the number of adsorbed rods as well as the length of adsorbed rods. This investigation can help us understand the complexity of the driven self-assembly of hard nanoplates on elastic shells. Project supported by the National Natural Science Foundation of China (Grant No.21174131).

  11. Applications of exchange coupled bi-magnetic hard/soft and soft/hard magnetic core/shell nanoparticles

    NASA Astrophysics Data System (ADS)

    López-Ortega, Alberto; Estrader, Marta; Salazar-Alvarez, German; Roca, Alejando G.; Nogués, Josep

    2015-02-01

    The applications of exchange coupled bi-magnetic hard/soft and soft/hard ferromagnetic core/shell nanoparticles are reviewed. After a brief description of the main synthesis approaches and the core/shell structural-morphological characterization, the basic static and dynamic magnetic properties are presented. Five different types of prospective applications, based on diverse patents and research articles, are described: permanent magnets, recording media, microwave absorption, biomedical applications and other applications. Both the advantages of the core/shell morphology and some of the remaining challenges are discussed.

  12. 77 FR 3771 - Notice of Issuance of Final Outer Continental Shelf Air Permit for Shell Offshore, Inc.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-25

    ... From the Federal Register Online via the Government Publishing Office ENVIRONMENTAL PROTECTION AGENCY Notice of Issuance of Final Outer Continental Shelf Air Permit for Shell Offshore, Inc. AGENCY... on November 30, 2011, EPA issued a final Outer Continental Shelf (OCS) air permit for Shell...

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

    NASA Astrophysics Data System (ADS)

    Nogues, Josep

    2013-03-01

    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. In collaboration with A. Lopez-Ortega, M. Estrader, G. Salazar-Alvarez, S. Estrade, F. Peiro, I.V. Golossvsky, M. Vasilakaki, K.N. Trohidou, R.K. Dumas, D.J. Keavney, M. Laver, K. Krycka, J. Borchers, M. Varela, S. Suriach, M.D. Baro, J. Sort

  14. Viscoelastic Relaxation of Tidally Induced Stresses in the Ice Shells of Outer Solar System Satellites

    NASA Astrophysics Data System (ADS)

    Crawford, Z. A.; Mullen, M.; Wahr, J.; Pappalardo, R. T.; Stempel, M. M.; Barr, A. C.; Collins, G.

    2006-12-01

    A significant fraction of icy satellites appear to have an ice shell decoupled from the moon's solid interior by a global ocean. Such satellites when in an eccentric orbit will experience diurnal tidal deformation and stresses within the shell. Further, non-synchronous rotation (NSR) of decoupled ice shells has been suggested as a potential source of large surface stresses. These stresses may be stored elastically, released through brittle failure, or relaxed away viscously. Prior work has focused on elastic behavior, since the surface temperatures in the outer solar system are so low. However, much of a convecting ice shell may be warm enough to behave viscously on NSR timescales. Near the melting point it may even be possible for some diurnal stress to relax away. We model an ice shell as two Maxwell viscoelastic layers with independent viscosities. Frequency dependent degree-two Love numbers are calculated assuming a silicate core, global ocean, and the two layer ice shell for both NSR and diurnal forcing frequencies. When orbital eccentricity is set to zero, we find that surface stresses due to NSR depend on the ratio of the NSR forcing period to the shell's relaxation time: γ = \\frac{PNSR}{τMaxwell} When γ >> 1 the shell behaves viscously, and when γ << 1 the shell behaves elastically. Since the upper and lower shells have different relaxation times, assuming the surface is colder than the interior there are three possible regimes: when both layers behave elastically, the resulting stresses are similar to previously published results. When both layers behave viscously, surface stresses are greatly reduced. When the upper layer behaves elastically, and the lower layer behaves viscously NSR stresses are effectively concentrated in the upper layer, and are somewhat larger than if the entire shell is elastic. As the elastic proportion of the shell is reduced, the magnitude of the surface stresses increases. When the lower shell behaves viscously and the upper shell behaves elastically, the surface stresses are very similar to those resulting from a thin elastic shell floating directly on a liquid ocean. If orbital eccentricity is non-zero and γ >> 1 for the upper layer, then the shorter period results in the diurnal stresses dominating. The existence of surface features on Europa that apparently stem from diurnal stresses suggests that at some point in the recent geologic past the upper shell has behaved viscously on the timescale of NSR. We would like to thank PG&G and OPR for their support of this research.

  15. Ultrastructural characteristics of ostrich eggshell: outer shell membrane and the calcified layers.

    PubMed

    Richards, P D; Richards, P A; Lee, M E

    2000-06-01

    The ultrastructure of the eggshell of the domestic hen has been well researched and structural studies of other avian species, such as the ostrich, often base their interpretation of egg shell structure on that of the chicken. In the ostrich, lowered hatchability and hatching trauma may be due to shell ultrastructural abnormalities. In the present study the ultrastructure of the calcified portion, and the outer shell membrane (OSM), of domesticated ostrich eggshells was investigated using standard electron microscopic techniques. Transmission and scanning electron microscopy studies demonstrated intimate contact between cup-shaped structures present on the OSM and the mammillary layer of the calcified portion of the shell. The initial calcium carbonate growth of the calcified shell was of a dendritic nature with nucleation sites on the surface of the cup's contents. The dendritic growth gave way to a more randomly-orientated, smaller crystallite growth structure, which changed in form as it neared the vertical crystal layer (VCL). The VCL is described as being both amorphous and 'crumbly' depending on the plane of fracture. These observations suggest that firstly, initial calcification is contained within the cups and is then directed outwards to form the shell and that secondly, the VCL may contain an evolutionary, calcified cuticular layer. These observations serve as a baseline for studies investigating the effect of shell structure and strength on hatchling trauma and the influence of maternal diet. PMID:11030359

  16. Design of small, hard-shell overflow dams on compressible foundations

    SciTech Connect

    Huang, B.; Gu, S.

    1998-04-01

    Considering the peculiarities of small hydropower station construction, the province of Hebei, China, has creatively built a series of hard-shell overflow dams on compressible foundations designed to meet the different geographic and geological characteristics of the sites. Structurally, locally collected stones are used as dam filter; then concrete or reinforced concrete is used to form a hard-shell overflow face slab. In upstream seepage control design, natural sealing methods are used to replace the artificial upstream blanket designs, in consideration of the river flow condition of high sediment density and high suspended sediment concentration. Based on the riverbed foundation characteristics and the hydrological properties, synthetic energy dissipation methods are used instead of the usual still plunge pool methods to simplify the dam structure and to reduce the construction cost. This is a theoretical study commissioned by the Hebei Bureau of Water Resources on the design of hard-shell overflow dams that have been constructed on compressible foundations. The major technical problems of constructing hard-shell dams on compressible foundations are (a) dam body stability and face slab structure stress analysis; (b) the influence of the settlement of the foundation and dam body on the face slab and the superstructure; (c) downstream energy dissipation and erosion control measures; and (d) seepage damage control measures of the dam body and foundation.

  17. Drug release from and mechanical properties of press-coated tablets with hydroxypropylmethylcellulose acetate succinate and plasticizers in the outer shell.

    PubMed

    Fukui, E; Miyamura, N; Yoneyama, T; Kobayashi, M

    2001-04-17

    Dissolution profiles of diltiazem hydrochloride (DIL) contained in core tablets from press-coated (PC) tablets with hydroxypropylmethylcellulose acetate succinate (HPMCAS) and plasticizers-adsorbent in the outer shell were investigated. Although, on the addition of triethyl citrate (TEC), triacetin (TA), and acetyltriethy citrate (ATEC) as plasticizers, DIL release was suppressed completely in first fluid (pH 1.2) for 10 h, it was not suppressed in HPMCAS on the addition of dibutyl sebacate (DBS) and acetylated monoglyceride. On the other hand, DIL in second fluid (pH 6.8) was released rapidly after a lag time in all the PC tablets. Water-soluble plasticizers such as TEC, TA, and ATEC showed greater compatibility to HPMCAS, and the results were consistent with suppression of DIL release in first fluid. Furthermore, as to PC tablets with HPMCAS and TEC-adsorbent, the DIL release in second fluid did not change after pretreatment in first fluid by the paddle-beads methods. To evaluate the resistance of the outer shell against such a mechanical impact, tablets with HPMCAS, HPMCAS and TEC- or DBS-adsorbent (H, HT, or HD tablets, respectively) were prepared. In compressive load-strain curves after immersion in first fluid, wet crushing strength was lower in the order of HT > H > HD tablets. Also, the curves of HT tablets at 3 and 21 h after immersion were quite different from those of other tablets, and it was hard to find crushing points. These results suggested that the resistance of the outer shell was due to plastic deformation properties involving some interaction between HPMCAS and TEC. PMID:11292540

  18. Inner and Outer Coordination Shells of Mg(2+) in CorA Selectivity Filter from Molecular Dynamics Simulations.

    PubMed

    Kitjaruwankul, Sunan; Wapeesittipan, Pattama; Boonamnaj, Panisak; Sompornpisut, Pornthep

    2016-01-28

    Structural data of CorA Mg(2+) channels show that the five Gly-Met-Asn (GMN) motifs at the periplasmic loop of the pentamer structure form a molecular scaffold serving as a selectivity filter. Unfortunately, knowledge about the cation selectivity of Mg(2+) channels remains limited. Since Mg(2+) in aqueous solution has a strong first hydration shell and apparent second hydration sphere, the coordination structure of Mg(2+) in a CorA selectivity filter is expected to be different from that in bulk water. Hence, this study investigated the hydration structure and ligand coordination of Mg(2+) in a selectivity filter of CorA using molecular dynamics (MD) simulations. The simulations reveal that the inner-shell structure of Mg(2+) in the filter is not significantly different from that in aqueous solution. The major difference is the characteristic structural features of the outer shell. The GMN residues engage indirectly in the interactions with the metal ion as ligands in the second shell of Mg(2+). Loss of hydrogen bonds between inner- and outer-shell waters observed from Mg(2+) in bulk water is mostly compensated by interactions between waters in the first solvation shell and the GMN motif. Some water molecules in the second shell remain in the selectivity filter and become less mobile to support the metal binding. Removal of Mg(2+) from the divalent cation sensor sites of the protein had an impact on the structure and metal binding of the filter. From the results, it can be concluded that the GMN motif enhances the affinity of the metal binding site in the CorA selectivity filter by acting as an outer coordination ligand. PMID:26727882

  19. 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

    Shang Yazhuo; Hu Jun; Liu Honglai; Hu Ying

    2010-03-15

    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.

  20. Building nanocomposite magnets by coating a hard magnetic core with a soft magnetic shell.

    PubMed

    Liu, Fei; Zhu, Jinghan; Yang, Wenlong; Dong, Yunhe; Hou, Yanglong; Zhang, Chenzhen; Yin, Han; Sun, Shouheng

    2014-02-17

    Controlling exchange coupling between hard magnetic and soft magnetic phases is the key to the fabrication of advanced magnets with tunable magnetism and high energy density. Using FePt as an example, control over the magnetism in exchange-coupled nanocomposites of hard magnetic face-centered tetragonal (fct) FePt and soft magnetic Co (or Ni, Fe2C) is shown. The dispersible hard magnetic fct-FePt nanoparticles are first prepared with their coercivity (Hc) reaching 33?kOe. Then core/shell fct-FePt/Co (or Ni, Fe2C) nanoparticles are synthesized by reductive thermal decomposition of the proper metal precursors in the presence of fct-FePt nanoparticles. These core/shell nanoparticles are strongly coupled by exchange interactions and their magnetic properties can be rationally tuned by the shell thickness of the soft phase. This work provides an ideal model system for the study of exchange coupling at the nanoscale, which will be essential for building superstrong magnets for various permanent magnet applications in the future. PMID:24453167

  1. Transcriptome response to copper heavy metal stress in hard-shelled mussel (Mytilus coruscus)

    PubMed Central

    Xu, Meiying; Jiang, Lihua; Shen, Kang-Ning; Wu, Changwen; He, Guangyuan; Hsiao, Chung-Der

    2015-01-01

    The hard-shelled mussel (Mytilus coruscus) has considerably one of the most economically important marine shellfish worldwide and considered as a good invertebrate model for ecotoxicity study for a long time. In the present study, we used Illumina sequencing technology (HiSeq2000) to sequence, assemble and annotate the transcriptome of the hard-shelled mussel which challenged with copper pollution. A total of 21,723,913 paired-end clean reads (NCBI SRA database SRX1411195) were generated from HiSeq2000 sequencer and 96,403 contigs (with N50 = 1118 bp) were obtained after de novo assembling with Trinity software. Digital gene expression analysis reveals 1156 unigenes are upregulated and 1681 unigenes are downregulated when challenged with copper. By KEGG pathway enrichment analysis, we found that unigenes in four KEGG pathways (aminoacyl-tRNA biosynthesis, apoptosis, DNA replication and mismatch repair) show significant differential expressed between control and copper treated groups. We hope that the gill transcriptome in copper treated hard-shelled mussel can give useful information to understand how mussel handles with heavy metal stress at molecular level. PMID:26981394

  2. Transcriptome response to copper heavy metal stress in hard-shelled mussel (Mytilus coruscus).

    PubMed

    Xu, Meiying; Jiang, Lihua; Shen, Kang-Ning; Wu, Changwen; He, Guangyuan; Hsiao, Chung-Der

    2016-03-01

    The hard-shelled mussel (Mytilus coruscus) has considerably one of the most economically important marine shellfish worldwide and considered as a good invertebrate model for ecotoxicity study for a long time. In the present study, we used Illumina sequencing technology (HiSeq2000) to sequence, assemble and annotate the transcriptome of the hard-shelled mussel which challenged with copper pollution. A total of 21,723,913 paired-end clean reads (NCBI SRA database SRX1411195) were generated from HiSeq2000 sequencer and 96,403 contigs (with N50 = 1118 bp) were obtained after de novo assembling with Trinity software. Digital gene expression analysis reveals 1156 unigenes are upregulated and 1681 unigenes are downregulated when challenged with copper. By KEGG pathway enrichment analysis, we found that unigenes in four KEGG pathways (aminoacyl-tRNA biosynthesis, apoptosis, DNA replication and mismatch repair) show significant differential expressed between control and copper treated groups. We hope that the gill transcriptome in copper treated hard-shelled mussel can give useful information to understand how mussel handles with heavy metal stress at molecular level. PMID:26981394

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

    PubMed

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

    2000-09-28

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

  4. Collision safety of a hard-shell low-mass vehicle.

    PubMed

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

    1994-06-01

    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 EuroSID1-dummy well below current injury tolerance criteria. PMID:8011053

  5. Imaging of hard X-rays from implosions of CH shells at Omega

    NASA Astrophysics Data System (ADS)

    Lemieux, Daniel; Grim, Gary; Barber, Brad; Aragonez, Robert; Clark, David; Danly, Chris

    2013-10-01

    Making use of the recently designed gamma ray imaging system prototype made for the National Ignition Facility, images of hard X-rays produced in implosions of plastic shells using the Omega laser are presented. Preheating from hot-electrons produced by two-plasmon-decay is a concern for direct drive implosions as it increases the adiabat of the fuel assembly. The hot-electrons undergo bremsstrahlung scattering in the CH material, producing X-rays ranging from a few keV to a few hundred keV. These X-rays are produced in implosions of 875 micron CH shells, filled with 3He, and are imaged using a 200 micron pinhole onto an LYSO scintillator system. Copper is used as a high-pass filter of the signal. A description of the gamma ray imaging diagnostic will be presented along with images of the hard X-rays. Prepared by LANL under Contract DE-AC-52-06-NA25396, TSPA.

  6. Outer electrospun polycaprolactone shell induces massive foreign body reaction and impairs axonal regeneration through 3D multichannel chitosan nerve guides.

    PubMed

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

    2014-01-01

    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

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

    PubMed Central

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

    2014-01-01

    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

  8. Equatorial symmetry of Boussinesq convective solutions in a rotating spherical shell allowing rotation of the inner and outer spheres

    SciTech Connect

    Kimura, Keiji; Takehiro, Shin-ichi; Yamada, Michio

    2014-08-15

    We investigate properties of convective solutions of the Boussinesq thermal convection in a moderately rotating spherical shell allowing the respective rotation of the inner and outer spheres due to the viscous torque of the fluid. The ratio of the inner and outer radii of the spheres, the Prandtl number, and the Taylor number are fixed to 0.4, 1, and 500{sup 2}, respectively. The Rayleigh number is varied from 2.6 10{sup 4} to 3.4 10{sup 4}. In this parameter range, the behaviours of obtained asymptotic convective solutions are almost similar to those in the system whose inner and outer spheres are restricted to rotate with the same constant angular velocity, although the difference is found in the transition process to chaotic solutions. The convective solution changes from an equatorially symmetric quasi-periodic one to an equatorially symmetric chaotic one, and further to an equatorially asymmetric chaotic one, as the Rayleigh number is increased. This is in contrast to the transition in the system whose inner and outer spheres are assumed to rotate with the same constant angular velocity, where the convective solution changes from an equatorially symmetric quasi-periodic one, to an equatorially asymmetric quasi-periodic one, and to equatorially asymmetric chaotic one. The inner sphere rotates in the retrograde direction on average in the parameter range; however, it sometimes undergoes the prograde rotation when the convective solution becomes chaotic.

  9. Wrinkle-assisted linear assembly of hard-core/soft-shell particles: impact of the soft shell on the local structure.

    PubMed

    Müller, Mareen; Karg, Matthias; Fortini, Andrea; Hellweg, Thomas; Fery, Andreas

    2012-04-01

    This article addresses wrinkle assisted assembly of core-shell particles with hard cores and soft poly-(N-isopropylacrylamide) shells. As core materials we chose silica as well as silver nanoparticles. The assembled structures show that the soft shells act as a separator between the inorganic cores. Anisotropic alignment is found on two length scales, macroscopically guided through the wrinkle structure and locally due to deformation of the polymer shell leading to smaller inter-core separations as compared to assembly on flat substrates without confinement. The structures were analysed by means of scanning electron microscopy. Radial distribution functions are shown, clearly highlighting the impact of confinement on nearest neighbour distances and symmetry. The observed ordering is directly compared to Monte-Carlo simulations for hard-core/soft-shell particles, showing that the observed symmetries are a consequence of the soft interaction potential and differ qualitatively from a hard-sphere situation. For the silver-poly-(N-isopropylacrylamide) particles, we show UV-vis absorbance measurements revealing optical anisotropy of the generated structures due to plasmon coupling. Furthermore, the high degree of order of the assembled structures on macroscopic areas is demonstrated by laser diffraction effects. PMID:22395669

  10. Some Investigations on Hardness of Investment Casting Process After Advancements in Shell Moulding for Reduction in Cycle Time

    NASA Astrophysics Data System (ADS)

    Singh, R.; Mahajan, V.

    2014-07-01

    In the present work surface hardness investigations have been made on acrylonitrile butadiene styrene (ABS) pattern based investment castings after advancements in shell moulding for replication of biomedical implants. For the present study, a hip joint, made of ABS material, was fabricated as a master pattern by fused deposition modelling (FDM). After preparation of master pattern, mold was prepared by deposition of primary (1°), secondary (2°) and tertiary (3°) coatings with the addition of nylon fibre (1-2 cm in length of 1.5D). This study outlines the surface hardness mechanism for cast component prepared from ABS master pattern after advancement in shell moulding. The results of study highlight that during shell production, fibre modified shells have a much reduced drain time. Further the results are supported by cooling rate and micro structure analysis of casting.

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

    SciTech Connect

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

    1987-01-29

    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.

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

    PubMed

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

    2013-07-15

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

  13. The F type mitochondrial genome of hard-shelled mussel: Mytilus coruscus (Mytiloida, Mytilidae).

    PubMed

    Lee, Yu-Cheol; Lee, Youn-Ho

    2016-01-01

    We determined the complete mitochondrial genome of the female hard-shelled mussel Mytilus coruscus (Gould, 1869) (F type). The F type genome is composed of 16,642 bp in length including 12 protein coding genes (PCGs), 2 rRNA and 23 tRNA with the same gene content and order as the other Mytilus species which is characterized by the absence of the ATPase8 gene and addition of tRNA(Met) (AUA). The nucleotide composition of the genome shows that the percentage of A+T (63.2%) is higher than those of M. edulis complex species (M. edulis, M. galloprovincialis, M. trossulus) but lower than that of M. californianus. The F type mitochondrial genome of M. coruscus will provide useful information on the evolutionary history of the Mytilus species in the family Mitilidae. PMID:24730572

  14. Shell hardness and compressive strength of the Eastern oyster, Crassostrea virginica, and the Asian oyster, Crassostrea ariakensis.

    PubMed

    Lombardi, Sara A; Chon, Grace D; Lee, James Jin-Wu; Lane, Hillary A; Paynter, Kennedy T

    2013-12-01

    The valves of oysters act as a physical barrier between tissues and the external environment, thereby protecting the oyster from environmental stress and predation. To better understand differences in shell properties and predation susceptibilities of two physiologically and morphologically similar oysters, Crassostrea virginica and Crassostrea ariakensis, we quantified and compared two mechanical properties of shells: hardness (resistance to irreversible deformation; GPa) and compressive strength (force necessary to produce a crack; N). We found no differences in the hardness values between foliated layers (innermost and outermost foliated layers), age class (C. virginica: 1, 4, 6, 9 years; C. ariakensis: 4, 6 years), or species. This suggests that the foliated layers have similar properties and are likely composed of the same material. The compressive force required to break wet and dry shells was also not different. However, the shells of both six- and nine-year-old C. virginica withstood higher compressive force than C. virginica shells aged either one or four, and the shells of C. ariakensis at both ages studied (4- and 6-years-old). Differences in ability to withstand compressive force are likely explained by differences in thickness and density between age classes and species. Further, we compared the compressive strength of differing ages of these two species to the crushing force of common oyster predators in the Chesapeake Bay. By studying the physical properties of shells, this work may contribute to a better understanding of the mechanical defenses of oysters as well as of their predation vulnerabilities. PMID:24445443

  15. Preparation of magnetic spinel ferrite core/shell nanoparticles: Soft ferrites on hard ferrites and vice versa

    NASA Astrophysics Data System (ADS)

    Masala, Ombretta; Hoffman, Darin; Sundaram, Nalini; Page, Katharine; Proffen, Thomas; Lawes, Gavin; Seshadri, Ram

    2006-09-01

    Hard/soft CoFe 2O 4/ZnFe 2O 4 and soft/hard ZnFe 2O 4/CoFe 2O 4 core/shell nanoparticles were prepared by combining high-temperature thermolysis of metal oxide precursors with seed-mediated growth. Magnetic properties of the core/shell nanoparticles were compared to those of individual CoFe 2O 4 and ZnFe 2O 4 nanoparticles of similar size prepared by the same method. The structure of the core/shell materials was established using a combination of X-ray and neutron powder diffraction, and transmission electron microscopy. Further evidence for core/shell structure was obtained from magnetic measurements using a SQUID magnetometer. Magnetization measurements as a function of temperature reveal that the core/shell nanoparticles display a single blocking temperature suggesting that the spins of the hard CoFe 2O 4 and the soft ZnFe 2O 4 are strongly coupled and respond jointly to changes of temperature and magnetic field. The blocking temperature increases according to the relative amount of hard magnetic material (CoFe 2O 4) in the nanoparticles in the range of 46-150 K. Magnetic measurements on the nanoparticles as pressed powders and as dispersions in paraffin wax indicate that interparticle interactions significantly influence magnetization and coercivity of the particles, and these must be taken into account before the magnetization behavior of the core/shell structures can be interpreted in terms of coupling between the soft and hard magnetic materials.

  16. Structural and electrical properties of core shell structured GaP nanowires with outer Ga2O3 oxide layers

    NASA Astrophysics Data System (ADS)

    Kim, B.-K.; Oh, H.; Jeon, E.-K.; Kim, S.-R.; Kim, J.-R.; Kim, J.-J.; Lee, J.-O.; Lee, C. J.

    2006-11-01

    This paper presents a review of our current experimental research on GaP nanowires grown by a vapor deposition method. Their structural, electrical, opto-electric transport, and gas-adsorption properties are reviewed. Our structural studies showed that a GaP nanowire consisted of a core shell structure with a single-crystalline GaP core and an outer Ga2O3 layer. The individual GaP nanowires exhibited n-type field effects. Their electron mobilities were in the range of about 6 to 22 cm2/V s at room temperature. When the nanowires were illuminated with an ultraviolet light source, an abrupt increase of conductance occurred resulting from carrier generation in the nanowire and de-adsorption of adsorbed OH- or O2 - ions on the Ga2O3 surface shell. Using an intrinsic Ga2O3 shell layer as a gate dielectric, top-gated GaP nanowire field-effect transistors were fabricated and characterized. Like other metal oxide nanowires, the carrier concentration and mobility of GaP nanowires were significantly affected by the surface molecular adsorption of OH or O2. The GaP nanowire devices were fabricated as sensors for NO2, NH3, and H2 gases by using a simple metal decoration technique.

  17. Double-Shelled Nanocages with Cobalt Hydroxide Inner Shell and Layered Double Hydroxides Outer Shell as High-Efficiency Polysulfide Mediator for Lithium-Sulfur Batteries.

    PubMed

    Zhang, Jintao; Hu, Han; Li, Zhen; Lou, Xiong Wen David

    2016-03-14

    Lithium-sulfur (Li-S) batteries have been considered as a promising candidate for next-generation electrochemical energy-storage technologies because of their overwhelming advantages in energy density. Suppression of the polysulfide dissolution while maintaining a high sulfur utilization is the main challenge for Li-S batteries. Here, we have designed and synthesized double-shelled nanocages with two shells of cobalt hydroxide and layered double hydroxides (CH@LDH) as a conceptually new sulfur host for Li-S batteries. Specifically, the hollow CH@LDH polyhedra with complex shell structures not only maximize the advantages of hollow nanostructures for encapsulating a high content of sulfur (75 wt %), but also provide sufficient self-functionalized surfaces for chemically bonding with polysulfides to suppress their outward dissolution. When evaluated as cathode material for Li-S batteries, the CH@LDH/S composite shows a significantly improved electrochemical performance. PMID:26894940

  18. Outer-Shell Double Photoionization of CH4 and CH2Cl2 Molecules

    NASA Astrophysics Data System (ADS)

    Alcantara, K. F.; Gomes, A. H. A.; Sigaud, L.; Wolf, W.; Santos, A. C. F.

    In this work the roles of the shake-off and knockout processes in the double photoionization of the CH2Cl2 and CH4 molecules have been studied. The probabilities for both mechanisms accompanying valence-shell photoionization have been estimated as a function of incident photon energy using Samson's (1990) and Thomas's (1994) models, respectively. The experimental results are in qualitative accord with the models.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

  20. Bubble generation and venous air filtration by hard-shell venous reservoirs: a comparative study.

    PubMed

    Mitchell, S J; Willcox, T; Gorman, D F

    1997-09-01

    We have previously shown significant bubble formation in Medtronic Maxima hard-shell venous reservoirs (HSVRs). In the present study, we not only investigated the mechanism of this bubble formation, but also the extent of bubble clearance by membrane oxygenators and arterial line filters. In addition, we also compared the performance of five HSVRs with respect to bubble formation and venous air filtration. Salvaged clinical CPB circuits containing different HSVRs were studied by downstream Doppler monitoring under fixed flow-decreasing volume, fixed volume-increasing flow, and entrained venous air conditions. Bubbles formed in the Medtronic Maxima top entry HSVR at volumes below 800 ml and flows above 3.5 l min-1, and were incompletely removed by a membrane oxygenator and arterial line filter. Decreased bubbling was seen when the reservoir atmosphere was flushed with CO2, suggesting that these bubbles formed in a fountain at the venous inflow. The Medtronic Maxima Forte HSVR formed significantly fewer bubbles at low volumes, and filtered venous air effectively. Negligible bubble formation occurred in the Sorin, Terumo, or Baxter reservoirs. The minimum recommended operating volume for the Medtronic Maxima top entry reservoir should be reset at 600 ml and this device should always be used with an arterial filter. Bubble formation is substantially reduced in the new Medtronic Maxima Forte HSVR and this device is a good filter for venous air. PMID:9300478

  1. Excitation and ionization of outer shells in Rb by electron impact

    NASA Astrophysics Data System (ADS)

    Roman, V.; Kupliauskienė, A.; Borovik, A.

    2015-10-01

    The relativistic distorted-wave and binary-encounter-dipole approximations were employed for calculating the electron-impact single ionization cross sections of the 5s, 4p6, 4s2, 3d10 shells and 4p6 excitation cross section for Rb atom taking into account both configuration interaction and relativistic effects. The capabilities of the most used theoretical approaches in describing the single ionization of Rb atom were considered by comparing the present and other available calculated data with the experimental total ionization and total direct single ionization cross sections over the electron-impact energy range from the 5s threshold to 600 eV. The best agreement within experimental uncertainty was obtained by using the non-relativistic binary-encounter-dipole approximation included in the LANL Atomic Physics Codes package. At present none of the used approximations (plane-wave Born or relativistic distorted wave) can satisfactorily describe the experimental excitation-autoionization cross section in rubidium because the efficient formation of the 4p6 core-excited negative-ion rubidium states at near-threshold impact energies is ignored in calculations.

  2. Light absorption and plasmon exciton interaction in three-layer nanorods with a gold core and outer shell composed of molecular J- and H-aggregates of dyes

    NASA Astrophysics Data System (ADS)

    Shapiro, B. I.; Tyshkunova, E. S.; Kondorskiy, A. D.; Lebedev, V. S.

    2015-12-01

    Optical properties of hybrid rod-like nanoparticles, consisting of a gold core, an intermediate passive organic layer (spacer) and outer layer of ordered molecular cyanine dye aggregates, are experimentally and theoretically investigated. It is shown that these dyes can form not only ordered J-aggregates but also H-aggregates (differing by the packing angle of dye molecules in an aggregate and having other spectral characteristics) in the outer shell of the hybrid nanostructure. Absorption spectra of synthesised three-layer nanorods are recorded, and their sizes are determined. The optical properties of the composite nanostructures under study are found to differ significantly, depending on the type of the molecular aggregate formed in the outer shell. The experimental data are quantitatively explained based on computer simulation using the finite-difference time-domain (FDTD) method, and characteristic features of the plasmon exciton interaction in the systems under study are revealed.

  3. Imprinting on empty hard gelatin capsule shells containing titanium dioxide by application of the UV laser printing technique.

    PubMed

    Hosokawa, Akihiro; Kato, Yoshiteru; Terada, Katsuhide

    2014-08-01

    The purpose of this study was to examine the application of ultraviolet (UV) laser irradiation to printing hard gelatin capsule shells containing titanium dioxide (TiO2) and to clarify how the color strength of the printing by the laser could be controlled by the power of the irradiated laser. Hard gelatin capsule shells containing 3.5% TiO2 were used in this study. The capsules were irradiated with pulsed UV laser at a wavelength of 355 nm. The color strength of the printed capsule was determined by a spectrophotometer as total color difference (dE). The capsules could be printed gray by the UV laser. The formation of many black particles which were agglomerates of oxygen-defected TiO2 was associated with the printing. In the relationship between laser peak power of a pulse and dE, there were two inflection points. The lower point was the minimal laser peak power to form the black particles and was constant regardless of the dosage forms, for example film-coated tablets, soft gelatin capsules and hard gelatin capsules. The upper point was the minimal laser peak power to form micro-bubbles in the shells and was variable with the formulation. From the lower point to the upper point, the capsules were printed gray and the dE of the printing increased linearly with the laser peak power. Hard gelatin capsule shells containing TiO2 could be printed gray using the UV laser printing technique. The color strength of the printing could be controlled by regulating the laser energy between the two inflection points. PMID:23786207

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

    SciTech Connect

    Milisavljevic, Dan; Fesen, Robert A.

    2013-08-01

    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.

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

    PubMed

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

    2013-11-18

    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 2.820.26 N for hypromellose capsules and 4.540.26 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

  6. Influence of capsule shell composition on the performance indicators of hypromellose capsule in comparison to hard gelatin capsules.

    PubMed

    Al-Tabakha, Moawia M; Arida, Adi Issam; Fahelelbom, Khairi M S; Sadek, Bassem; Saeed, Dima Ahmed; Abu Jarad, Rami A; Jawadi, Jeevani

    2015-01-01

    The purpose of this study was to assess the in vitro performances of "vegetable" capsules in comparison to hard gelatin capsules in terms of shell weight variation, reaction to different humidity conditions, resistance to stress in the absence of moisture, powder leakage, disintegration and dissolution. Two types of capsules made of HPMC produced with (Capsule 2) or without (Capsule 3) a gelling agent and hard gelatin capsules (Capsule 1) were assessed. Shell weight variability was relatively low for all tested capsules shells. Although Capsule 1 had the highest moisture content under different humidity conditions, all capsule types were unable to protect the encapsulated hygroscopic polyvinylpyrrolidone (PVP) powder from surrounding humidity. The initial disintegration for all Capsule 1 occurred within 3?min, but for other types of capsules within 6?min (n?=?18). Dissolution of acetaminophen was better when the deionized water (DIW) temperature increased from 32 to 42?C in case of Capsule 1, but the effect of temperature was not significant for the other types of capsules. Acetaminphen dissolution from Capsule 1 was the fastest (i.e. >90% in 10?min) and independent of the media pH or contents unlike Capsule 2 which was influenced by the pH and dissolution medium contents. It is feasible to use hypromellose capsules shells with or without gelling agent for new lines of pharmaceutical products, however, there is a window for capsule shells manufacturing companies to improve the dissolution of their hypromellose capsules to match the conventional gelatin capsule shells and eventually replace them. PMID:25586554

  7. Migration of Salmonella Enteritidis PT 30 through almond hulls and shells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of Salmonella to migrate from an external aqueous environment through the almond hull and shell, and to colonize the kernel, was evaluated in two ways. First, the outer surface of shell halves from five varieties of almonds that differed in shell hardness were placed in contact with a s...

  8. Molecular characterization of alpha-keratins in comparison to associated beta-proteins in soft-shelled and hard-shelled turtles produced during the process of epidermal differentiation.

    PubMed

    Dalla Valle, L; Michieli, F; Benato, F; Skobo, T; Alibardi, L

    2013-11-01

    The tough corneous layer in the carapace and plastron of hard-shelled turtles derives from the accumulation of keratin-associated beta-proteins (KAbetaPs, formerly called beta-keratins) while these proteins are believed to be absent in soft-shelled turtles. Our bioinformatics and molecular study has instead shown that the epidermis of the soft-shelled turtle Apalone spinifera expresses beta-proteins like or even in higher amount than in the hard-shelled turtle Pseudemys nelsoni. The analysis of a carapace cDNAs library has allowed the identification and characterization of three alpha-keratins of type I and of ten beta-proteins (beta-keratins). The acidic alpha-keratins probably combine with the basic beta-proteins but the high production of beta-proteins in A. spinifera is not prevalent over that of alpha-keratin so that their combination does not determine the formation of hard corneous material. Furthermore the presence of a proline and cisteine in the beta-sheet region of beta-proteins in A. spinifera may be unsuited to form hard masses of corneous material. The higher amount of beta-proteins over alpha-keratins instead occurs in keratinocytes of the hard and inflexible epidermis of P. nelsoni determining the deposition of hard corneous material. The study suggests that the hardness of the corneous layer derives not exclusively from the interactions between alpha-keratins with KAbetaPs but also from the different dynamic of accumulation and loss of corneocytes in the corneous layer of the hard shelled turtles where a prevalent accumulation and piling of corneocytes takes place versus the soft shelled turtle where a rapid turnover of the stratum corneum occurs. PMID:23794440

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

    USGS Publications Warehouse

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

    1995-01-01

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

  10. 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

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

    2010-10-15

    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

  11. Hard sphere packings within cylinders.

    PubMed

    Fu, Lin; Steinhardt, William; Zhao, Hao; Socolar, Joshua E S; Charbonneau, Patrick

    2016-02-23

    Arrangements of identical hard spheres confined to a cylinder with hard walls have been used to model experimental systems, such as fullerenes in nanotubes and colloidal wire assembly. Finding the densest configurations, called close packings, of hard spheres of diameter σ in a cylinder of diameter D is a purely geometric problem that grows increasingly complex as D/σ increases, and little is thus known about the regime for D > 2.873σ. In this work, we extend the identification of close packings up to D = 4.00σ by adapting Torquato-Jiao's adaptive-shrinking-cell formulation and sequential-linear-programming (SLP) technique. We identify 17 new structures, almost all of them chiral. Beyond D ≈ 2.85σ, most of the structures consist of an outer shell and an inner core that compete for being close packed. In some cases, the shell adopts its own maximum density configuration, and the stacking of core spheres within it is quasiperiodic. In other cases, an interplay between the two components is observed, which may result in simple periodic structures. In yet other cases, the very distinction between the core and shell vanishes, resulting in more exotic packing geometries, including some that are three-dimensional extensions of structures obtained from packing hard disks in a circle. PMID:26843132

  12. Evaluating the sensitivity, reproducibility and flexibility of a method to test hard shell capsules intended for use in dry powder inhalers.

    PubMed

    Chong, Rosalind H E; Jones, Brian E; Díez, Fernando; Birchall, James C; Coulman, Sion A

    2016-03-16

    Pharmaceutical tests for hard shell capsules are designed for orally administered capsules. The use of capsules in dry powder inhalers is widespread and increasing and therefore more appropriate tests are required to ensure quality and determine if these capsules are fit for purpose. This study aims to determine the flexibility, reproducibility and sensitivity of a quantitative method that is designed to evaluate the puncture characteristics of different capsule shell formulations under different climatic conditions. A puncture testing method was used to generate force displacement curves for five capsule formulations that were stored and tested at two different temperatures (5°C and 19°C). Force-displacement puncture profiles were reproducible for individual capsule shell formulations. The methodology was able to discriminate between capsules produced using different primary materials i.e. gelatin versus hypromellose, as well as more minor changes to capsule formulation i.e. different material grades and excipients. Reduced temperature increased the forces required for capsule puncture however further work is required to confirm its significance. Results indicate the method provides a reproducible and sensitive means of evaluating capsule puncture. Future studies should validate the methodology at different test sites, using different operators and with different capsule shell formulations. PMID:26806464

  13. LC and ferromagnetic resonance in soft/hard magnetic microwires

    NASA Astrophysics Data System (ADS)

    Tian, Bin; Vazquez, Manuel

    2015-12-01

    The magnetic behavior of soft/hard biphase microwires is introduced here. The microwires consist of a Co59.1Fe14.8Si10.2B15.9 soft magnetic nucleus and a Co90Ni10 hard outer shell separated by an intermediate insulating Pyrex glass microtube. By comparing the resistance spectrums of welding the ends of metallic core (CC) or welding the metallic core and outer shell (CS) to the connector, it is found that one of the two peaks in the resistance spectrum is because the LC resonance depends on the inductor and capacitors in which one is the capacitor between the metallic core and outer shell, and the other is between the outer shell and connector. Correspondingly, another peak is for the ferromagnetic resonance of metallic core. After changing the capacitance of the capacitors, the frequency of LC resonance moves to high frequency band, and furthermore, the peak of LC resonance in the resistance spectrum disappeared. These magnetostatically coupled biphase systems are thought to be of large potential interest as sensing elements in sensor devices.

  14. Structural Determinants of the Outer Shell of ?-Carboxysomes in Synechococcus elongatus PCC 7942: Roles for CcmK2, K3-K4, CcmO, and CcmL

    PubMed Central

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

    2012-01-01

    Cyanobacterial CO2-fixation is supported by a CO2-concentrating mechanism which improves photosynthesis by saturating the primary carboxylating enzyme, ribulose 1, 5-bisphosphate carboxylase/oxygenase (RuBisCO), with its preferred substrate CO2. The site of CO2-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-CO2-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 CO2 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

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

    PubMed

    Biscardi, Brianna; Welsh, Wendy; Kennedy, Anthony

    2012-05-01

    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

  16. Anti-Inflammatory Activity and Mechanism of a Lipid Extract from Hard-Shelled Mussel (Mytilus Coruscus) on Chronic Arthritis in Rats

    PubMed Central

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

    2014-01-01

    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 B4 (LTB4), prostaglandin E2 (PGE2), thromboxane B2 (TXB2) in the serum, and interleukin-1β (IL-1β), IL-6, interferon-γ (INF-γ), tumor necrosis factor-α (TNF-α) 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 (LTB4, PGE2, TXB2), pro-inflammatory cytokines (IL-1β, IL-6, INF-γ, TNF-α) and MMPs (MMP1, MMP13), and the promotion of anti-inflammatory cytokines (IL-4, IL-10) and TIMPs (TIMP1) productions. PMID:24473164

  17. Interfacial effect on physical properties of composite media: Interfacial volume fraction with non-spherical hard-core-soft-shell-structured particles.

    PubMed

    Xu, Wenxiang; Duan, Qinglin; Ma, Huaifa; Chen, Wen; Chen, Huisu

    2015-01-01

    Interfaces are known to be crucial in a variety of fields and the interfacial volume fraction dramatically affects physical properties of composite media. However, it is an open problem with great significance how to determine the interfacial property in composite media with inclusions of complex geometry. By the stereological theory and the nearest-surface distribution functions, we first propose a theoretical framework to symmetrically present the interfacial volume fraction. In order to verify the interesting generalization, we simulate three-phase composite media by employing hard-core-soft-shell structures composed of hard mono-/polydisperse non-spherical particles, soft interfaces, and matrix. We numerically derive the interfacial volume fraction by a Monte Carlo integration scheme. With the theoretical and numerical results, we find that the interfacial volume fraction is strongly dependent on the so-called geometric size factor and sphericity characterizing the geometric shape in spite of anisotropic particle types. As a significant interfacial property, the present theoretical contribution can be further drawn into predicting the effective transport properties of composite materials. PMID:26522701

  18. Interfacial effect on physical properties of composite media: Interfacial volume fraction with non-spherical hard-core-soft-shell-structured particles

    NASA Astrophysics Data System (ADS)

    Xu, Wenxiang; Duan, Qinglin; Ma, Huaifa; Chen, Wen; Chen, Huisu

    2015-11-01

    Interfaces are known to be crucial in a variety of fields and the interfacial volume fraction dramatically affects physical properties of composite media. However, it is an open problem with great significance how to determine the interfacial property in composite media with inclusions of complex geometry. By the stereological theory and the nearest-surface distribution functions, we first propose a theoretical framework to symmetrically present the interfacial volume fraction. In order to verify the interesting generalization, we simulate three-phase composite media by employing hard-core-soft-shell structures composed of hard mono-/polydisperse non-spherical particles, soft interfaces, and matrix. We numerically derive the interfacial volume fraction by a Monte Carlo integration scheme. With the theoretical and numerical results, we find that the interfacial volume fraction is strongly dependent on the so-called geometric size factor and sphericity characterizing the geometric shape in spite of anisotropic particle types. As a significant interfacial property, the present theoretical contribution can be further drawn into predicting the effective transport properties of composite materials.

  19. Interfacial effect on physical properties of composite media: Interfacial volume fraction with non-spherical hard-core-soft-shell-structured particles

    PubMed Central

    Xu, Wenxiang; Duan, Qinglin; Ma, Huaifa; Chen, Wen; Chen, Huisu

    2015-01-01

    Interfaces are known to be crucial in a variety of fields and the interfacial volume fraction dramatically affects physical properties of composite media. However, it is an open problem with great significance how to determine the interfacial property in composite media with inclusions of complex geometry. By the stereological theory and the nearest-surface distribution functions, we first propose a theoretical framework to symmetrically present the interfacial volume fraction. In order to verify the interesting generalization, we simulate three-phase composite media by employing hard-core-soft-shell structures composed of hard mono-/polydisperse non-spherical particles, soft interfaces, and matrix. We numerically derive the interfacial volume fraction by a Monte Carlo integration scheme. With the theoretical and numerical results, we find that the interfacial volume fraction is strongly dependent on the so-called geometric size factor and sphericity characterizing the geometric shape in spite of anisotropic particle types. As a significant interfacial property, the present theoretical contribution can be further drawn into predicting the effective transport properties of composite materials. PMID:26522701

  20. Ocean acidification alters the material properties of Mytilus edulis shells

    PubMed Central

    Fitzer, Susan C.; Zhu, Wenzhong; Tanner, K. Elizabeth; Phoenix, Vernon R.; Kamenos, Nicholas A.; Cusack, Maggie

    2015-01-01

    Ocean acidification (OA) and the resultant changing carbonate saturation states is threatening the formation of calcium carbonate shells and exoskeletons of marine organisms. The production of biominerals in such organisms relies on the availability of carbonate and the ability of the organism to biomineralize in changing environments. To understand how biomineralizers will respond to OA the common blue mussel, Mytilus edulis, was cultured at projected levels of pCO2 (380, 550, 750, 1000 µatm) and increased temperatures (ambient, ambient plus 2°C). Nanoindentation (a single mussel shell) and microhardness testing were used to assess the material properties of the shells. Young's modulus (E), hardness (H) and toughness (KIC) were measured in mussel shells grown in multiple stressor conditions. OA caused mussels to produce shell calcite that is stiffer (higher modulus of elasticity) and harder than shells grown in control conditions. The outer shell (calcite) is more brittle in OA conditions while the inner shell (aragonite) is softer and less stiff in shells grown under OA conditions. Combining increasing ocean pCO2 and temperatures as projected for future global ocean appears to reduce the impact of increasing pCO2 on the material properties of the mussel shell. OA may cause changes in shell material properties that could prove problematic under predation scenarios for the mussels; however, this may be partially mitigated by increasing temperature. PMID:25540244

  1. Ocean acidification alters the material properties of Mytilus edulis shells.

    PubMed

    Fitzer, Susan C; Zhu, Wenzhong; Tanner, K Elizabeth; Phoenix, Vernon R; Kamenos, Nicholas A; Cusack, Maggie

    2015-02-01

    Ocean acidification (OA) and the resultant changing carbonate saturation states is threatening the formation of calcium carbonate shells and exoskeletons of marine organisms. The production of biominerals in such organisms relies on the availability of carbonate and the ability of the organism to biomineralize in changing environments. To understand how biomineralizers will respond to OA the common blue mussel, Mytilus edulis, was cultured at projected levels of pCO2 (380, 550, 750, 1000 µatm) and increased temperatures (ambient, ambient plus 2°C). Nanoindentation (a single mussel shell) and microhardness testing were used to assess the material properties of the shells. Young's modulus (E), hardness (H) and toughness (KIC) were measured in mussel shells grown in multiple stressor conditions. OA caused mussels to produce shell calcite that is stiffer (higher modulus of elasticity) and harder than shells grown in control conditions. The outer shell (calcite) is more brittle in OA conditions while the inner shell (aragonite) is softer and less stiff in shells grown under OA conditions. Combining increasing ocean pCO2 and temperatures as projected for future global ocean appears to reduce the impact of increasing pCO2 on the material properties of the mussel shell. OA may cause changes in shell material properties that could prove problematic under predation scenarios for the mussels; however, this may be partially mitigated by increasing temperature. PMID:25540244

  2. Micromechanical properties and structural characterization of modern inarticulated brachiopod shells

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

    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.

  3. Thermally activated coercivity in core-shell permanent magnets

    NASA Astrophysics Data System (ADS)

    Bance, S.; Fischbacher, J.; Schrefl, T.

    2015-05-01

    Finite element micromagnetic simulations are used to compute the temperature-dependent hysteresis properties of Nd2Fe14B permanent magnets in order to assess the influence of a hard (Dy,Nd)2Fe14B shell. The simulations show that the 4 nm thick shell cancels out the reduction in coercivity from an outer defect layer, which is known to exist at the grain boundaries in NdFeB permanent magnets. Activation volumes are computed and shown to depend on the structure's configuration as well as the temperature.

  4. Lipid Extract from Hard-Shelled Mussel (Mytilus coruscus) Improves Clinical Conditions of Patients with Rheumatoid Arthritis: A Randomized Controlled Trial

    PubMed Central

    Fu, Yuanqing; Li, Guipu; Zhang, Xinhua; Xing, Gengyan; Hu, Xiaojie; Yang, Lifeng; Li, Duo

    2015-01-01

    Studies have suggested a lipid extract from hard-shelled mussel (Mytilus coruscus) (HMLE) possessed strong anti-inflammatory activity in arthritis model of rats. This study investigated whether HMLE could improve clinical conditions of rheumatoid arthritis patients. Fifty rheumatoid arthritis patients (28–75 years) were randomly assigned to receive HMLE capsules or receive placebo capsules for 6 months. Forty-two subjects and 50 subjects were included in per-protocol and intention-to-treat analysis, respectively. Significant differences in changes on disease activity score (DAS28) and clinical disease activity index (CDAI) after 6-month intervention (p < 0.01) were observed in both analyses with more evident efficacy shown in per-protocol population (∆DAS28 = 0.47; ∆CDAI = 4.17), which favored the benefits of the HMLE group. TNF-α (tumor necrosis factor α), interleukin (IL)-1β and PGE2 (prostaglandin E2) but not IL-6, were significantly decreased in both groups, and the decrements were much larger in the HMLE group for TNF-α and PGE2 after 6 months from baseline (p < 0.05). IL-10 was significantly increased in both groups and the change was much more evident in the HMLE group (p < 0.05). In conclusion, HMLE exhibited benefits for the clinical conditions of rheumatoid patients in relation to improvement in the balance between pro- and anti-inflammatory factors, which indicated its potential to serve as adjunctive treatment for rheumatoid arthritis. (ClinicalTrials.gov NCT02173587). PMID:25602164

  5. Material with core-shell structure

    DOEpatents

    Luhrs, Claudia; Richard, Monique N.; Dehne, Aaron; Phillips, Jonathan; Stamm, Kimber L.; Fanson, Paul T.

    2011-11-15

    Disclosed is a material having a composite particle, the composite particle including an outer shell and a core. The core is made from a lithium alloying material and the outer shell has an inner volume that is greater in size than the core of the lithium alloying material. In some instances, the outer mean diameter of the outer shell is less than 500 nanometers and the core occupies between 5 and 99% of the inner volume. In addition, the outer shell can have an average wall thickness of less than 100 nanometers.

  6. Multi-Shell Hollow Nanogels with Responsive Shell Permeability

    PubMed Central

    Schmid, Andreas J.; Dubbert, Janine; Rudov, Andrey A.; Pedersen, Jan Skov; Lindner, Peter; Karg, Matthias; Potemkin, Igor I.; Richtering, Walter

    2016-01-01

    We report on hollow shell-shell nanogels with two polymer shells that have different volume phase transition temperatures. By means of small angle neutron scattering (SANS) employing contrast variation and molecular dynamics (MD) simulations we show that hollow shell-shell nanocontainers are ideal systems for controlled drug delivery: The temperature responsive swelling of the inner shell controls the uptake and release, while the thermoresponsive swelling of the outer shell controls the size of the void and the colloidal stability. At temperatures between 32 °C < T < 42 °C, the hollow nanocontainers provide a significant void, which is even larger than the initial core size of the template, and they possess a high colloidal stability due to the steric stabilization of the swollen outer shell. Computer simulations showed, that temperature induced switching of the permeability of the inner shell allows for the encapsulation in and release of molecules from the cavity. PMID:26984478

  7. The ultrastructure of shelled and unshelled cashew nuts.

    PubMed

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

    2013-01-01

    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

  8. 46 CFR 154.170 - Outer hull steel plating.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Outer hull steel plating. 154.170 Section 154.170... Structure § 154.170 Outer hull steel plating. (a) Except as required in paragraph (b) of this section, the outer hull steel plating, including the shell and deck plating must meet the material standards of...

  9. 46 CFR 154.170 - Outer hull steel plating.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Outer hull steel plating. 154.170 Section 154.170... Structure § 154.170 Outer hull steel plating. (a) Except as required in paragraph (b) of this section, the outer hull steel plating, including the shell and deck plating must meet the material standards of...

  10. 46 CFR 154.170 - Outer hull steel plating.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Outer hull steel plating. 154.170 Section 154.170... Structure § 154.170 Outer hull steel plating. (a) Except as required in paragraph (b) of this section, the outer hull steel plating, including the shell and deck plating must meet the material standards of...

  11. 46 CFR 154.170 - Outer hull steel plating.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Outer hull steel plating. 154.170 Section 154.170... Structure § 154.170 Outer hull steel plating. (a) Except as required in paragraph (b) of this section, the outer hull steel plating, including the shell and deck plating must meet the material standards of...

  12. 46 CFR 154.170 - Outer hull steel plating.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Outer hull steel plating. 154.170 Section 154.170... Structure § 154.170 Outer hull steel plating. (a) Except as required in paragraph (b) of this section, the outer hull steel plating, including the shell and deck plating must meet the material standards of...

  13. Shell forming apparatus

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Granett, Dan (Inventor); Akutagawa, Wesley M. (Inventor)

    1987-01-01

    A nozzle assembly is described for use in a system that forms small gas-filled shells, which avoids the need for holding a miniature inner nozzle precisely concentric with a miniature outer nozzle. The outer nozzle has a diameter which is less than about 0.7 millimeter, which results in fluid passing through the nozzle having a progressively greater velocity at locations progressively further from the walls of the outer nozzle across most of the nozzle. This highly variable velocity profile automatically forces gas to the center of the outer nozzle. The end of the inner nozzle, which emits gas, is spaced upstream from the tip of the outer nozzle, to provide a distance along which to center the gas. This self-centering characteristic permits the inner nozzle to be positioned so its axis is not concentric with the axis of the outer nozzle.

  14. Multiple shell fusion targets

    DOEpatents

    Lindl, J.D.; Bangerter, R.O.

    1975-10-31

    Multiple shell fusion targets for use with electron beam and ion beam implosion systems are described. The multiple shell targets are of the low-power type and use a separate relatively low Z, low density ablator at large radius for the outer shell, which reduces the focusing and power requirements of the implosion system while maintaining reasonable aspect ratios. The targets use a high Z, high density pusher shell placed at a much smaller radius in order to obtain an aspect ratio small enough to protect against fluid instability. Velocity multiplication between these shells further lowers the power requirements. Careful tuning of the power profile and intershell density results in a low entropy implosion which allows breakeven at low powers. For example, with ion beams as a power source, breakeven at 10-20 Terrawatts with 10 MeV alpha particles for imploding a multiple shell target can be accomplished.

  15. Thick-shell nanocrystal quantum dots

    DOEpatents

    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

    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.

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

    PubMed

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

    2014-06-16

    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

  17. Optimum rotationally symmetric shells for flywheel rotors

    SciTech Connect

    Blake, Henry W.

    2000-01-01

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

  18. Optimum rotationally symmetric shells for flywheel rotors

    SciTech Connect

    Blake, H.W.

    2000-04-04

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

  19. Removable inner turbine shell with bucket tip clearance control

    DOEpatents

    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

    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.

  20. G359.97-0.038: A Hard X-Ray Filament Associated with a Supernova Shell-Molecular Cloud Interaction

    NASA Astrophysics Data System (ADS)

    Nynka, Melania; Hailey, Charles J.; Zhang, Shuo; Morris, Mark M.; Zhao, Jun-Hui; Goss, Miller; Bauer, Franz E.; Boggs, Stephen E.; Craig, William W.; Christensen, Finn E.; Gotthelf, Eric V.; Harrison, Fiona A.; Mori, Kaya; Perez, Kerstin M.; Stern, Daniel; Zhang, William W.

    2015-02-01

    We present the first high-energy X-ray (>10 keV) observations of the non-thermal filament G359.97-0.038 using the Nuclear Spectroscopic Telescope Array (NuSTAR). This filament is one of approximately 20 X-ray filaments of unknown origin located in the central 20 pc region in the Galactic Center near Sgr A*. Its NuSTAR and Chandra broadband spectrum is characterized by a single power law with ? = 1.3 0.3 that extends from 2 to 50 keV, with an unabsorbed luminosity of 1.3 1033 erg s-1 (d/8 kpc)2 in the 2-8 keV band. Despite possessing a cometary X-ray morphology that is typical of a pulsar wind nebula (PWN) in high-resolution Chandra imaging, our spatially resolved Chandra spectral analysis found no significant spectral softening along the filament as would be expected from particle synchrotron cooling. Coincident radio emission is detected using the Very Large Array at 5.5 and 8.3 GHz. We examine and subsequently discard a PWN or magnetic flux tube as the origin of G359.97-0.038. We use broadband spectral characteristics and a morphological analysis to show that G359.97-0.038 is likely an interaction site between the shell of Sgr A East and an adjacent molecular cloud. This is supported by CS molecular line spectroscopy and the presence of an OH maser.

  1. Shell and coil heat exchanger

    SciTech Connect

    Dempsey, J.C.

    1993-07-20

    A heat exchanger is described comprising: a shell having: a tubular outer wall having a first and second end, a tubular inner wall having a first and second end coaxial with the outer wall, and first and second end plates attached to the first and second ends of the outer and inner walls to form an enclosed tubular shell cavity there between having a first and second end; means for admitting a first fluid into the shell cavity; means for removing the first fluid from the shell cavity; a spiral coil of tubing having a first and second end sealingly exiting through the shell cavity wall for carrying a second fluid there between, the spiral coil lying within the shell cavity and having a plurality of spiral windings formed about the axis thereof, the spiral coil sized to fit between the inner and outer shell wall with limited radial clearance to allow limited axial flow of the first fluid, the winding axially spaced from one another to define a spiral flow path there between for the first fluid, the radial clearance and axial spacing relatively sized to induce the first fluid to travel in a substantially spiral motion to enhance the heat transfer between the first and second fluids; an auxiliary coil of tubing having a first and second end sealing extending through the shell cavity for carrying a third fluid there between, the auxiliary coil lying within the shell cavity and having a plurality of windings formed about the axis thereof and axially spaced apart from the spiral coil, for transferring heat between the first and third fluids; and a divider plate dividing the shell cavity into two coaxial cylindrical regions, a primary region in which lies the spiral coil and an auxiliary region in which lies the auxiliary coil, and means to admit and means to remove a fourth fluid from the auxiliary region.

  2. Method to produce large, uniform hollow spherical shells

    DOEpatents

    Hendricks, Charles D. (Livermore, CA)

    1985-01-01

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

  3. Diffusion, sedimentation, and rheology of concentrated suspensions of core-shell particles.

    PubMed

    Abade, Gustavo C; Cichocki, Bogdan; Ekiel-Je?ewska, Maria L; Ngele, Gerhard; Wajnryb, Eligiusz

    2012-03-14

    Short-time dynamic properties of concentrated suspensions of colloidal core-shell particles are studied using a precise force multipole method which accounts for many-particle hydrodynamic interactions. A core-shell particle is composed of a rigid, spherical dry core of radius a surrounded by a uniformly permeable shell of outer radius b and hydrodynamic penetration depth ?(-1). The solvent flow inside the permeable shell is described by the Brinkman-Debye-Bueche equation, and outside the particles by the Stokes equation. The particles are assumed to interact non-hydrodynamically by a hard-sphere no-overlap potential of radius b. Numerical results are presented for the high-frequency shear viscosity, ?(?), sedimentation coefficient, K, and the short-time translational and rotational self-diffusion coefficients, D(t) and D(r). The simulation results cover the full three-parametric fluid-phase space of the composite particle model, with the volume fraction extending up to 0.45, and the whole range of values for ?b, and a/b. Many-particle hydrodynamic interaction effects on the transport properties are explored, and the hydrodynamic influence of the core in concentrated systems is discussed. Our simulation results show that for thin or hardly permeable shells, the core-shell systems can be approximated neither by no-shell nor by no-core models. However, one of our findings is that for ?(b - a) ? 5, the core is practically not sensed any more by the weakly penetrating fluid. This result is explained using an asymptotic analysis of the scattering coefficients entering into the multipole method of solving the Stokes equations. We show that in most cases, the influence of the core grows only weakly with increasing concentration. PMID:22423856

  4. Sound Transmission through Two Concentric Cylindrical Sandwich Shells

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    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.

  5. The Outer Limits: English.

    ERIC Educational Resources Information Center

    Tyler, Barbara R.; Biesekerski, Joan

    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

  6. Method of fabricating nested shells and resulting product

    DOEpatents

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

    1982-01-01

    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.

  7. Core-shell nanostructured catalysts.

    PubMed

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

    2013-08-20

    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

  8. Outer planet satellites

    SciTech Connect

    Schenk, P.M. )

    1991-01-01

    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.

  9. Turbine blade with spar and shell

    DOEpatents

    Davies, Daniel O.; Peterson, Ross H.

    2012-04-24

    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.

  10. Role of shell crossing on the existence and stability of trapped matter shells in spherical inhomogeneous ?-CDM models

    NASA Astrophysics Data System (ADS)

    Le Delliou, Morgan; Mena, Filipe C.; Mimoso, Jos P.

    2011-05-01

    We analyze the dynamics of trapped matter shells in spherically symmetric inhomogeneous ?-CDM models. The investigation uses a generalized Lematre-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.

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

    SciTech Connect

    Le Delliou, Morgan; Mena, Filipe C.; Mimoso, Jose P.

    2011-05-15

    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.

  12. Saturn's outer magnetosphere

    NASA Technical Reports Server (NTRS)

    Schardt, A. W.; Behannon, K. W.; Carbary, J. F.; Eviatar, A.; Lepping, R. P.; Siscoe, G. L.

    1983-01-01

    Similarities between the Saturnian and terrestrial outer magnetosphere are examined. Saturn, like Earth, has a fully developed magnetic tail, 80 to 100 RS in diameter. One major difference between the two outer magnetospheres is the hydrogen and nitrogen torus produced by Titan. This plasma is, in general, convected in the corotation direction at nearly the rigid corotation speed. Energies of magnetospheric particles extend to above 500 keV. In contrast, interplanetary protons and ions above 2 MeV have free access to the outer magnetosphere to distances well below the Stormer cutoff. This access presumably occurs through the magnetotail. In addition to the H+, H2+, and H3+ ions primarily of local origin, energetic He, C, N, and O ions are found with solar composition. Their flux can be substantially enhanced over that of interplanetary ions at energies of 0.2 to 0.4 MeV/nuc.

  13. Ionic bonding of lanthanides, as influenced by d- and f-atomic orbitals, by core-shells and by relativity.

    PubMed

    Ji, Wen-Xin; Xu, Wei; Schwarz, W H Eugen; Wang, Shu-Guang

    2015-03-15

    Lanthanide trihalide molecules LnX3 (X = F, Cl, Br, I) were quantum chemically investigated, in particular detail for Ln = Lu (lutetium). We applied density functional theory (DFT) at the nonrelativistic and scalar and SO-coupled relativistic levels, and also the ab initio coupled cluster approach. The chemically active electron shells of the lanthanide atoms comprise the 5d and 6s (and 6p) valence atomic orbitals (AO) and also the filled inner 4f semivalence and outer 5p semicore shells. Four different frozen-core approximations for Lu were compared: the (1s(2) -4d(10) ) [Pd] medium core, the [Pd+5s(2) 5p(6) = Xe] and [Pd+4f(14) ] large cores, and the [Pd+4f(14) +5s(2) 5p(6) ] very large core. The errors of LuX bonding are more serious on freezing the 5p(6) shell than the 4f(14) shell, more serious upon core-freezing than on the effective-core-potential approximation. The LnX distances correlate linearly with the AO radii of the ionic outer shells, Ln(3+) -5p(6) and X(-) -np(6) , characteristic for dominantly ionic Ln(3+) -X(-) binding. The heavier halogen atoms also bind covalently with the Ln-5d shell. Scalar relativistic effects contract and destabilize the LuX bonds, spin orbit coupling hardly affects the geometries but the bond energies, owing to SO effects in the free atoms. The relativistic changes of bond energy BE, bond length Re , bond force k, and bond stretching frequency vs do not follow the simple rules of Badger and Gordy (Re ∼BE∼k∼vs ). The so-called degeneracy-driven covalence, meaning strong mixing of accidentally near-degenerate, nearly nonoverlapping AOs without BE contribution is critically discussed. PMID:25565146

  14. Law in Outer Space.

    ERIC Educational Resources Information Center

    Schmidt, William G.

    1997-01-01

    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,

  15. Snail Shell

    USGS Multimedia Gallery

    Plant seems to be a Heliotropum sp. Huge snail shells litter the wetland around Asuncion Bay. Near 251549S, 573747W. La plantita detrs del caracol parece ser un Heliotropium sp., Boraginaceae....

  16. Outer planets probe testing

    NASA Technical Reports Server (NTRS)

    Smittkamp, J. A.; Grote, M. G.; Edwards, T. M.

    1977-01-01

    An atmospheric entry Probe is being developed by NASA Ames Research Center (ARC) to conduct in situ scientific investigations of the outer planets' atmospheres. A full scale engineering model of an MDAC-E Probe configuration, was fabricated by NASA ARC. Proof-of-concept test validation of the structural and thermal design is being obtained at NASA ARC. The model was successfully tested for shock and dynamic loading and is currently in thermal vacuum testing.

  17. Shelled opisthobranchs.

    PubMed

    Mikkelsen, Paula M

    2002-01-01

    In his contributions to the monographic series "Manual of Conchology", Henry Pilsbry reviewed the subgroup Tectibranchiata, comprising those opisthobranch snails that (at least primitively) still possess a shell (Pilsbry, 1894-1896). Exemplified by the Cephalaspidea (bubble shells), others included in this group at Pilsbry's time and since were Anaspidea (sea hares) and the shelled members of Notaspidea (side-gilled slugs) and Sacoglossa (leaf slugs). Pilsbry (and others since his time) considered tectibranchs to be the "root stock" from which more advanced gastropods such as Nudibranchia and Pulmonata were derived. Tectibranch systematics is firmly based on conchology and most species were originally described from empty shells. However, soft-anatomical characters were acknowledged quite early on as equally important in tectibranchs, due to the reduction of their shells and their evolutionary proximity to unshelled gastropods. Today, Tectibranchiata is not recognized as a natural taxon although the word "tectibranch" (like "prosobranch" and "mesogastropod") continues in vernacular use. Shelled opisthobranchs have been redistributed among various taxa, including several new ones--the unresolved basal opisthobranchs (Architectibranchia) and the "lower Heterobranchia", an enigmatic and currently much-studied group of families considered basal to all of Euthyneura (Opisthobranchia and landsnails (Pulmonata)). Despite their polyphyletic status, shelled opisthobranchs remain important subjects in evolutionary studies of gastropods--as the most basal members of nearly every opisthobranch clade and as organisms with mosaic combinations of primitive and derived features within evolutionary "trends" (e.g., loss of the shell, detorsion, concentration of the nervous system, ecological specialization, etc.). Although they play a pivotal role, the shelled opisthobranchs have received minimal attention in more comprehensive gastropod studies, often relegated to token representatives at the derived end of prosobranchs or at the basal end of nudibranchs. The choice of this representative in a larger study is critical if its morphology and/or molecules are to adequately exemplify a larger group. This review explores the shelled opisthobranchs, including their history, current status and presumed synapomorphies, and emphasizes the importance of anatomical data to our current understanding of these "transitional" forms. A synthetic phylogenetic analysis, based on a combination of characters used in four published phylogenies involving tectibranchs, shows the current state of our knowledge and emphasizes areas for future study. The results indicate that Opisthobranchia, Cephalaspidea and Sacoglossa are monophyletic taxa, and that Acteon, the traditional basal opisthobranch, is convincingly a lower heterobranch. In most of the resulting cladograms, Anaspidea formed a monophyletic group with Cephalaspidea, as did pleurobranchoidean Notaspidea with Nudibranchia (the latter recently named as Nudipleura Wägele and Willan, 2000). PMID:12094725

  18. Photoionization of the outer electrons in noble gas endohedral atoms

    SciTech Connect

    Amusia, M. Ya. Baltenkov, A. S.; Chernysheva, L. V.

    2008-08-15

    We suggest a prominent modification of the outer shell photoionization cross section in noble gas (NG) endohedral atoms NG-C{sub n} under the action of the electron shell of fullerene C{sub n}. This shell leads to two important effects: a strong enhancement of the cross section due to fullerene shell polarization under the action of the incoming electromagnetic wave and to prominent oscillation of this cross section due to the reflection of a photoelectron from the NG by the fullerene shell. Both factors lead to powerful maxima in the outer shell ionization cross sections of NG-C{sub n}, which we call giant endohedral resonances. The oscillator strength reaches a very large value in the atomic scale, 25. We consider atoms of all noble gases except He. The polarization of the fullerene shell is expressed in terms of the total photoabsorption cross section of the fullerene. The photoelectron reflection is taken into account in the framework of the so-called bubble potential, which is a spherical {delta}-type potential. It is assumed in the derivations that the NG is centrally located in the fullerene. It is also assumed, in accordance with the existing experimental data, that the fullerene radius R{sub C} is much larger than the atomic radius r{sub A} and the thickness {delta}{sub C} of the fullerene shell. As was demonstrated recently, these assumptions allow us to represent the NG-C{sub n} photoionization cross section as a product of the NG cross section and two well-defined calculated factors.

  19. Jupiter's outer atmosphere.

    NASA Technical Reports Server (NTRS)

    Brice, N. M.

    1973-01-01

    The current state of the theory of Jupiter's outer atmosphere is briefly reviewed. The similarities and dissimilarities between the terrestrial and Jovian upper atmospheres are discussed, including the interaction of the solar wind with the planetary magnetic fields. Estimates of Jovian parameters are given, including magnetosphere and auroral zone sizes, ionospheric conductivity, energy inputs, and solar wind parameters at Jupiter. The influence of the large centrifugal force on the cold plasma distribution is considered. The Jovian Van Allen belt is attributed to solar wind particles diffused in toward the planet by dynamo electric fields from ionospheric neutral winds, and the consequences of this theory are indicated.

  20. Outer Solar System Nomenclature

    NASA Technical Reports Server (NTRS)

    Owen, Tobias C.

    1998-01-01

    The Principal Investigator's responsibilities on this grant fell into two categories according to his participation. In the nomenclature work of the International Astronomical Union (IAU). Owen is chair of the Task Group for the Outer Solar System. He is also a member of the IAU's Working Group on Planetary and Satellite Nomenclature (WGPSN) which is composed of the chairs of the several Task Groups plus the presidents of two IAU Commissions and several outside consultants. The WGPSN is presided over by its President, Professor Kaare Aksnes from the Rosseland Institute for Theoretical Astrophysics in Oslo, Norway.

  1. The microindentation behavior of several mollusk shells

    SciTech Connect

    Laraia, V.J.; Heuer, A.H. . Dept. of Materials Science and Engineering)

    1990-01-01

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

  2. Probabilistic Dynamic Buckling of Smart Composite Shells

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Abumeri, Galib H.

    2007-01-01

    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.

  3. Probabilistic Dynamic Buckling of Smart Composite Shells

    NASA Technical Reports Server (NTRS)

    Abumeri, Galib H.; Chamis, Christos C.

    2003-01-01

    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.

  4. Shell-in-Shell TiO2 hollow microspheres and optimized application in light-trapping perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Sun, Hongxia; Ruan, Peng; Bao, Zhongqiu; Chen, Lei; Zhou, Xingfu

    2015-02-01

    The shell-in-shell structured TiO2 hollow microspheres with enhanced light scattering ability were synthesized via a facile one step hydrothermal process. The diameter of the microsphere is about 1.5 ?m, the core of the unique shell-in-shell structure is composed of TiO2 nanoparticles with a diameter of about 15 nm, while the shell is constructed with ?50 nm TiO2 nanocubes. The hollow space between the outer shell and the inner shell is about 230 nm. The formation mechanism of the unique shell-in-shell structure is interpreted. The design and the optimized application of shell-in-shell structured TiO2 hollow microspheres in the light-trapping perovskite solar cells are also investigated. Owing to the light scattering properties of the shell-in-shell structure of the hollow microsphere, the optimized photoelectrode exhibits an enhanced photoelectric conversion efficiency of 4.29% using perovskite CH3NH3PbI3 as the sensitizer. The shell-in-shell hollow TiO2 microsphere shows a 21.2% increase in conversion efficiency when compared with P25 nanoparticels photoanode. The conversion efficiency enhancement is mainly attributed to the increase of short-current density induced by the light scattering effect.

  5. Outer planets satellites

    NASA Technical Reports Server (NTRS)

    Morrison, D.

    1983-01-01

    The present investigation takes into account the published literature on outer planet satellites for 1979-1982. It is pointed out that all but three (the moon and the two Martian satellites) of the known planetary satellites are found in the outer solar system. Most of these are associated with the three regular satellite systems of Jupiter, Saturn, and Uranus. The largest satellites are Titan in the Saturn system and Ganymede and Callisto in the Jupiter system. Intermediate in size between Mercury and Mars, each has a diameter of about 5000 km. Presumably each has an internal composition about 60 percent rock and 40 ice, and each is differentiated with a dense core extending out about 75 percent of the distance to the surface, with a mantle of high-pressure ice and a crust of ordinary ice perhaps 100 km thick. Attention is also given to Io, Europa, the icy satellites of Saturn, the satellites of Uranus, the small satellites of Jupiter and Saturn, Triton and the Pluto system, and plans for future studies.

  6. Shell Games.

    ERIC Educational Resources Information Center

    Atkinson, Bill

    1982-01-01

    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)

  7. Snail Shell

    USGS Multimedia Gallery

    Plant seems to be a Heliotropum sp. Huge snail shells litter the wetland around Asuncion Bay. Near 25°15’49’’S, 57°37’47’’W. La plantita detrás del caracol parece ser un Heliotropium sp., Boraginaceae....

  8. Energetic particle drift motions in the outer dayside magnetosphere

    SciTech Connect

    Buck, R.M.

    1987-12-01

    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.

  9. The development of the mammalian outer and middleear.

    PubMed

    Anthwal, Neal; Thompson, Hannah

    2016-02-01

    The mammalian ear is a complex structure divided into three main parts: the outer; middle; and inner ear. These parts are formed from all three germ layers and neural crest cells, which have to integrate successfully in order to form a fully functioning organ of hearing. Any defect in development of the outer and middle ear leads to conductive hearing loss, while defects in the inner ear can lead to sensorineural hearing loss. This review focuses on the development of the parts of the ear involved with sound transduction into the inner ear, and the parts largely ignored in the world of hearing research: the outer and middle ear. The published data on the embryonic origin, signalling, genetic control, development and timing of the mammalian middle and outer ear are reviewed here along with new data showing the Eustachian tube cartilage is of dual embryonic origin. The embryonic origin of some of these structures has only recently been uncovered (Science, 339, 2013, 1453; Development, 140, 2013, 4386), while the molecular mechanisms controlling the growth, structure and integration of many outer and middle ear components are hardly known. The genetic analysis of outer and middle ear development is rather limited, with a small number of genes often affecting either more than one part of the ear or having only very small effects on development. This review therefore highlights the necessity for further research into the development of outer and middle ear structures, which will be important for the understanding and treatment of conductive hearing loss. PMID:26227955

  10. Inner and outer beauty.

    PubMed

    Raymond, Kenneth N; Brown, Casey J

    2012-01-01

    Symmetry and pattern are precious forms of beauty that can be appreciated on both the macroscopic and molecular scales. Crystallographers have long appreciated the intimate connections between symmetry and molecular structure, reflected in their appreciation for the artwork of Escher. This admiration has been applied in the design of highly symmetrical coordination compounds. Two classes of materials are discussed: extended coordination arrays and discrete supramolecular assemblies. Extended coordination polymers have been implemented in gas separation and storage due to the remarkably porosity of these materials, aided by the ability to design ever-larger inner spaces within these frameworks. In the case of discrete symmetrical structures, defined inner and outer space present a unique aesthetic and chemical environment. The consequent host-guest chemistry and applications in catalysis are discussed. PMID:22076081

  11. Building Atoms Shell by Shell.

    ERIC Educational Resources Information Center

    Sussman, Beverly

    1993-01-01

    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

  12. Vibration of Shells

    NASA Technical Reports Server (NTRS)

    Leissa, A. W.

    1973-01-01

    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.

  13. Shell worlds

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

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

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

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

  15. Strategy for outer planets exploration

    NASA Technical Reports Server (NTRS)

    1975-01-01

    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 in a series of symposia to evaluate the potential outer planet missions and to discuss strategies for exploration of the outer solar system that were consistent with fiscal constraints and with anticipated spacecraft and launch vehicle capabilities. A logical, scientifically sound, and cost effective approach to exploration of the outer solar system is presented.

  16. Method to produce large, uniform hollow spherical shells

    DOEpatents

    Hendricks, C.D.

    1983-09-26

    The invention is a method to produce large uniform hollow spherical shells by (1) forming uniform size drops of heat decomposable or vaporizable material, (2) evaporating the drops to form dried particles, (3) coating the dried particles with a layer of shell forming material and (4) heating the composite particles to melt the outer layer and to decompose or vaporize the inner particle to form an expanding inner gas bubble. The expanding gas bubble forms the molten outer layer into a shell of relatively large diameter. By cycling the temperature and pressure on the molten shell, nonuniformities in wall thickness can be reduced. The method of the invention is utilized to produce large uniform spherical shells, in the millimeter to centimeter diameter size range, from a variety of materials and of high quality, including sphericity, concentricity and surface smoothness, for use as laser fusion or other inertial confinement fusion targets as well as other applications.

  17. Extreme electron fluxes in the outer zone

    NASA Astrophysics Data System (ADS)

    O'Brien, T. P.; Fennell, J. F.; Roeder, J. L.; Reeves, G. D.

    2007-01-01

    Following the work of Koons (2001), we examine the statistical properties of extremely high fluxes of MeV electrons in the outer zone. We extend the analysis to include a variety of timescales and energies using observations from Los Alamos monitors at geosynchronous orbit and to include outer zone fluxes observed from L 2-8 by spacecraft in highly elliptical Molniya orbits. We use the statistical formalism of the generalized extreme value distribution, which represents the probability distribution of the maximum value taken out of a sample of fixed size. By taking the maximum flux observed in many nonoverlapping intervals of several hours to several days, we can determine whether the maximum flux is likely to have a finite upper limit or an exponential or power law tail. Our analysis indicates that MeV electron fluxes over a broad range of energies, L shells, and timescales have a finite upper limit, a true worst case. However, the statistical estimate of this upper limit is inherently uncertain. We compare our upper limits to the internal charging specifications provided by Fennell et al. (2000). We discuss several possible physical explanations for the flux limits.

  18. Chemistry and processing of polymer shells

    NASA Astrophysics Data System (ADS)

    Alfonso, Emmanuel Limjuco

    The fabrication of high-quality spherical shells, used as fuel capsules in fusion experiments, is essential to the progress of the inertial confinement fusion program. Two types of shell were produced: (1) Polystyrene shells were made in a microencapsulation method. The yield, diameter, wall thickness, vacuole content, and surface finish were determined for shells prepared with an organic phase of toluene and 1,2-dichloroethane with polystyrene concentrations varied from 5 to 13 wt% and an internal water phase that sometimes contained surfactants. (2) Polyimide shells were made by vapor-phase deposition onto depolymerizable spherical mandrels. High-aspect-ratio polyimide shells with diameters ranging from 700 to 1000 mum and wall thicknesses from 2 to 13 mum have been fabricated. Estimates of the composition, surface roughness, burst and buckle pressures, elastic modulus, tensile strength, permeability, and film stress have been obtained. These shells have been characterized in terms of morphological properties: the shell dimensions (diameter and wall thickness), sphericity, wall structure, outer and inner surface finish, and transparency. The structure of the outer surface and wall cross section varied strongly with the processing conditions (e.g., deposition temperatures, system pressure), while the inner surface was shown to be very smooth. The transparency of near-stoichiometric polyimide shells and flat films was demonstrated. Rutherford backscattering and nuclear resonance analysis techniques were used to provide the elemental composition and density, which were very near the theoretical values. Polyimide shells' minimum tensile strengths and moduli were determined from burst and buckle pressure tests. The tensile strength approached that reported for Kapton-HN film. The elastic moduli varied with processing conditions. The vapor-deposited polyimide was found to possess mechanical strength properties similar to commercially available polyimides. The room-temperature permeabilities were measured for polyamic acid and polyimide shells and flat films. The D 2 and N2 permeabilities for shells and flat films from earlier versions of the deposition systems were orders of magnitude higher than the reported literature values. The D2 and He permeabilities for shells from more recent system configurations were nearly identical to the reported literature values.

  19. Structures in the Outer Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Fletcher, L.; Cargill, P. J.; Antiochos, S. K.; Gudiksen, B. V.

    2015-05-01

    The structure and dynamics of the outer solar atmosphere are reviewed with emphasis on the role played by the magnetic field. Contemporary observations that focus on high resolution imaging over a range of temperatures, as well as UV, EUV and hard X-ray spectroscopy, demonstrate the presence of a vast range of temporal and spatial scales, mass motions, and particle energies present. By focusing on recent developments in the chromosphere, corona and solar wind, it is shown that small scale processes, in particular magnetic reconnection, play a central role in determining the large-scale structure and properties of all regions. This coupling of scales is central to understanding the atmosphere, yet poses formidable challenges for theoretical models.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  1. The Leptospiral Outer Membrane

    PubMed Central

    Haake, David A; Zückert, Wolfram R

    2015-01-01

    The outer membrane (OM) is the front line of leptospiral interactions with their environment and the mammalian host. Unlike most invasive spirochetes, pathogenic leptospires must be able survive in both free-living and host-adapted states. As organisms move from one set of environmental conditions to another, the OM must cope with a series of conflicting challenges. For example, the OM must be porous enough to allow nutrient uptake, yet robust enough to defend the cell against noxious substances. In the host, the OM presents a surface decorated with adhesins and receptors for attaching to, and acquiring, desirable host molecules such as the complement regulator, Factor H. On the other hand, the OM must enable leptospires to evade detection by the host’s immune system on their way from sites of invasion through the bloodstream to the protected niche of the proximal tubule. The picture that is emerging of the leptospiral OM is that, while it shares many of the characteristics of the OMs of spirochetes and Gram-negative bacteria, it is also unique and different in ways that make it of general interest to microbiologists. For example, unlike most other pathogenic spirochetes, the leptospiral OM is rich in lipopolysaccharide (LPS). Leptospiral LPS is similar to that of Gram-negative bacteria but has a number of unique structural features that may explain why it is not recognized by the LPS-specific Toll-like receptor 4 of humans. As in other spirochetes, lipoproteins are major components of the leptospiral OM, though their roles are poorly understood. The functions of transmembrane OMPs in many cases are better understood thanks to homologies with their Gram-negative counterparts and the emergence of improved genetic techniques. This chapter will review recent discoveries involving the leptospiral OM and its role in leptospiral physiology and pathogenesis. Readers are referred to earlier, excellent summaries related to this subject (Adler and de la Peña Moctezuma, 2010; Cullen et al., 2004; Haake, 2000; Haake and Matsunaga, 2010; Ko et al., 2009; Raja and Natarajaseenivasan, 2013; Zuerner et al., 2000). PMID:25388136

  2. Separating in shell pistachio nuts from kernels using impact vibration analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    SciTech Connect

    M. M. Lewis

    2001-11-27

    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).

  4. Turbine airfoil with outer wall thickness indicators

    DOEpatents

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

    2013-08-06

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

  5. Acetabular shell deformation as a function of shell stiffness and bone strength.

    PubMed

    Dold, Philipp; Pandorf, Thomas; Flohr, Markus; Preuss, Roman; Bone, Martin C; Joyce, Tom J; Holland, James; Deehan, David

    2016-04-01

    Press-fit acetabular shells used for hip replacement rely upon an interference fit with the bone to provide initial stability. This process may result in deformation of the shell. This study aimed to model shell deformation as a process of shell stiffness and bone strength. A cohort of 32 shells with two different wall thicknesses (3 and 4 mm) and 10 different shell sizes (44- to 62-mm outer diameter) were implanted into eight cadavers. Shell deformation was then measured in the cadavers using a previously validated ATOS Triple Scan III optical system. The shell-bone interface was then considered as a spring system according to Hooke's law and from this the force exerted on the shell by the bone was calculated using a combined stiffness consisting of the measured shell stiffness and a calculated bone stiffness. The median radial stiffness for the 3-mm wall thickness was 4192 N/mm (range, 2920-6257 N/mm), while for the 4-mm wall thickness the median was 9633 N/mm (range, 6875-14,341 N/mm). The median deformation was 48 µm (range, 3-187 µm), while the median force was 256 N (range, 26-916 N). No statistically significant correlation was found between shell stiffness and deformation. Deformation was also found to be not fully symmetric (centres 180° apart), with a median angle discrepancy of 11.5° between the two maximum positive points of deformation. Further work is still required to understand how the bone influences acetabular shell deformation. PMID:26888887

  6. Outer pseudoring in the galaxy

    NASA Astrophysics Data System (ADS)

    Mel'Nik, A. M.

    2006-01-01

    The kinematics of the Sagittarius (R = 5.7 kpc),Carina (R = 6.5 kpc), Cygnus (R = 6.8 kpc), and Perseus (R = 8.2 kpc) arms suggests the existence of two spiral patterns in the Galaxy that rotate with different speeds. The inner spiral pattern that is represented by the Sagittarius arm rotates with the speed of the bar, b = 60 5 km s-1 kpc-1, while the outer spiral pattern that includes the Carina, Cygnus, and Perseus arms rotates with a lower speed, s = 12 22 km s-1 kpc-1.The existence of an outer slow tightly wound spiral pattern and an inner fast spiral pattern can be explained by numerically simulating the dynamics of outer pseudorings. The outer Lindblad resonance of the bar must be located between the Sagittarius and Carina arms. The Cygnus arm appears as a connecting link between the fast and slow spiral patterns.

  7. Thermoelectric Outer Planets Spacecraft (TOPS)

    NASA Technical Reports Server (NTRS)

    1973-01-01

    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.

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

    SciTech Connect

    Hamilton, K.E.; Letts, S.A.; Buckley, S.R.; Fearon, E.M.; Wilemski, G.; Cook, R.C.; Schroen-Carey, D.

    1997-03-01

    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.

  9. Handbook of hard coatings

    SciTech Connect

    Bunshah, R.; Weissmantel, C.

    2000-07-01

    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.

  10. Shell structure characteristics of pelagic and benthic molluscs from Antarctic waters

    NASA Astrophysics Data System (ADS)

    Sato-Okoshi, Waka; Okoshi, Kenji; Sasaki, Hiroshi; Akiha, Fumihiro

    2010-08-01

    The surface of the shell of the pelagic Antarctic gastropod, Limacina helicina antarctica forma antarctica, was smooth, with rib-like structures also observed. The larger specimen, with six to seven whorls, had visible ribs on its most outer whorl. The shell thickness of L. helicina antarctica forma antarctica was very thin, approximately 5-7 ?m, on an individual with a shell diameter of 1.4 mm. Shell microstructure, as examined by SEM, was composed mostly of a crossed-lamellar structure. Shell thickness of the dominant benthic bivalve Laternula elliptica, was approximately 99-132 ?m on an individual of shell length 19 mm. It was composed of two calcareous layers, including a thick outer homogeneous or granular layer and a thin nacreous inner layer. The characteristics of shell structure are discussed with reference to previous results, and in terms of adaptation to Antarctic waters.

  11. FIRST 100 T NON-DESTRUCTIVE MAGNET OUTER COIL SET

    SciTech Connect

    J. BACON; A. BACA; ET AL

    1999-09-01

    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.

  12. Nuclear shells, sub-shells and shell evolution

    NASA Astrophysics Data System (ADS)

    Bentley, Ian

    2015-04-01

    Shell structure in nuclei is seen in transition rates, binding energies and the energetics of excited states. The robustness of shells have been tested using extrema and differential observables. The shell and sub-shell closures between 8 <= N , Z <= 50 , and missing signatures of shells will be a primary focus, as will the migration of shells in energies of 61+,81+, and 101+ states. Pairing correlations have been determined across the chart of the nuclides using linear fits as a function of I(I + 1) for I >= 20 yrast states. These correlations occur at roughly the same locations as binging energy based correlations, but are noticeably larger in magnitude. A discussion of the comparison of experimentally determined pairing correlations and pairing calculations using the BCS formalism for gadolinium nuclei will be included.

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

    SciTech Connect

    DiMarco, M.J.; Nummedal, D.

    1986-01-01

    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.

  14. Nanorod and nanoparticle shells in concentration gradient core-shell lithium oxides for rechargeable lithium batteries.

    PubMed

    Yoon, Sung-June; Myung, Seung-Taek; Noh, Hyung-Joo; Lu, Jun; Amine, Khalil; Sun, Yang-Kook

    2014-12-01

    The structure, electrochemistry, and thermal stability of concentration gradient core-shell (CGCS) particles with different shell morphologies were evaluated and compared. We modified the shell morphology from nanoparticles to nanorods, because nanorods can result in a reduced surface area of the shell such that the outer shell would have less contact with the corrosive electrolyte, resulting in improved electrochemical properties. Electron microscopy studies coupled with electron probe X-ray micro-analysis revealed the presence of a concentration gradient shell consisting of nanoparticles and nanorods before and after thermal lithiation at high temperature. Rietveld refinement of the X-ray diffraction data and the chemical analysis results showed no variations of the lattice parameters and chemical compositions of both produced CGCS particles except for the degree of cation mixing (or exchange) in Li and transition metal layers. As anticipated, the dense nanorods present in the shell gave rise to a high tap density (2.5 g?cm(-3) ) with a reduced pore volume and surface area. Intimate contact among the nanorods is likely to improve the resulting electric conductivity. As a result, the CGCS Li[Ni0.60 Co0.15 Mn0.25 ]O2 with the nanorod shell retained approximately 85.5% of its initial capacity over 150 cycles in the range of 2.7-4.5 V at 60?C. The charged electrode consisting of Li0.16 [Ni0.60 Co0.15 Mn0.25 ]O2 CGCS particles with the nanorod shell also displayed a main exothermic reaction at 279.4?C releasing 751.7?J?g(-1) of heat. Due to the presence of the nanorod shell in the CGCS particles, the electrochemical and thermal properties are substantially superior to those of the CGCS particles with the nanoparticle shell. PMID:25044175

  15. Mussel Shell Evaluation as Bioindicator For Heavy Metals

    NASA Astrophysics Data System (ADS)

    Andrello, Avacir Casanova; Lopes, Fbio; Galvo, Tiago Dutra

    2010-05-01

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

  16. The Fabrication of Replicated Optics for Hard X-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Speegle, C. O.; Ramsey, B. D.; Engelhaupt, D.

    2000-01-01

    We describe the fabrication process for producing shallow-graze-angle mirrors for hard x-ray astronomy. This presentation includes the generation of the necessary super-polished mandrels, their metrology, and the subsequent mirror shell electroforming and testing.

  17. Distributed neural signals on parabolic cylindrical shells

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  18. Ordering of hard particles between hard walls

    NASA Astrophysics Data System (ADS)

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

    2001-05-01

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

  19. Ormosils of high hardness

    SciTech Connect

    Iwamoto, Takashi; Mackenzie, J.D.

    1994-12-31

    Organically modified silicates (ormosils) of high hardness were prepared by the reactions of tetraethoxysilane (TEOS) and polydimethylsiloxane (PDMS) aided by ultrasonic irradiation. The mechanisms leading to the hard ormosil formation were investigated by liquid state {sup 29}Si NMR spectroscopy. PDMS chains were found to be broken into shorter chains and/or 4-membered siloxane rings during the reaction and finally, all PDMS chains were chemically incorporated as short chains into silica networks. Vickers hardnesses of the hard ormosils were measured and compared with those of the hardest transparent plastics. Whereas the hardest transparent plastics have Vickers hardness values of less than 25 kg/mm{sup 2}, the hard ormosils have Vickers hardnesses tip to higher than 150 kg/mm{sup 2}. A theoretical model was developed for the calculation of Vickers hardnesses of the hard ormosils and agreed well with experimental results. Predictions based on this theory indicate that even harder ormosils can be made when Al{sub 2}O{sub 3}, ZrO{sub 2} and TiO{sub 2} are substituted for SiO{sub 2}. Results based on these new ormosils are also presented.

  20. 75 FR 3915 - Environmental Documents Prepared in Support of Sand and Gravel Activities on the Outer...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-25

    ... Minerals Management Service Environmental Documents Prepared in Support of Sand and Gravel Activities on... for three sand and gravel activities proposed on the Outer Continental Shelf (OCS) and described in... noncompetitive basis, the rights to OCS sand, gravel, or shell resources for shore protection, beach or...

  1. 76 FR 3152 - Agency Information Collection Activity: 1010-NEW, Upcoming Projects Considering the Use of Outer...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-19

    ... September 7, 2010, we published a Federal Register notice (75 FR 54369) announcing that we would submit this...: 1010-NEW, Upcoming Projects Considering the Use of Outer Continental Shelf (OCS) Sand, Gravel, and... respondents will submit to BOEMRE to obtain OCS sand, gravel, and shell resources for use in shore...

  2. Magnetic properties of core/shell nanoparticles with magnetic or nonmagnetic shells

    NASA Astrophysics Data System (ADS)

    Sebt, S. A.; Bakhshayeshi, A.; Abolhassani, M. R.

    2012-09-01

    In a model presented here, the effects of interparticle exchange and random magnetocrystalline anisotropy are added to the previous models of magnetization reversal for core/shell nanostructures in order to achieve better agreement with experimental data. The results from this model are compared with ones from the Stoner-Wohlfarth model in order to help us to interpret the shell thickness dependence of the coercivity in FePt/Fe3O4 core/shell nanoparticles and describe the difference between the results from the Stoner-Wohlfarth model and experimental data arising as the shell thickness increases. For magnetic shells in the FePt/Fe3O4 core/shell system, the effective coupling between particles increases with increasing shell thickness, which leads to coercivity destruction for stronger couplings. The nucleation mode penetrates from the soft phase into the hard phase when the exchange energy density is able to compete against the random anisotropy. According to the boundary conditions, in the harder regions with higher exchange stiffness, the magnetization variation should be small and so the magnetization modes should become more localized. We discuss localized and delocalized modes. The nonlocalized modes propagating in the soft phase for the non-zero shell thickness can have an effect on the quality of particle exchange interactions. In the case of nonmagnetic shells in the FePt/SiO2 core/shell system, the same model predicts a coercivity increase with increasing shell thickness. The increase in coercivity is due to the weakening of the particle coupling with the increasingly nonmagnetic shell. We present a model for exchange bias in these systems in order to interpret the coupling effects for the core and shell in the core/shell system. Chemical intermixing at the interface leads to spin glass-like behavior of the core/shell interface which affects the strength of coupling of the core and shell spins. In the random anisotropy model there is not so much of an effect when just high anisotropy cores and we do not expect a major difference between the superparamagnetic limits predicted by the Stoner-Wohlfarth and exchange models. Considering a bulging mode to occur in the core will have an effect on the results due to the magnetization reversal mechanisms.

  3. Physics of the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Gazis, P. R.

    1991-01-01

    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.

  4. Plasmas in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Belcher, J. W.; Richardson, J. D.; Lazarus, A. J.; Gazis, P. R.; Barnes, A.

    1995-01-01

    We review the observed properties of the solar wind in the outer heliosphere, including observations from Voyager and the Pioneers, as well as from inner heliospheric probes as appropriate. These observations are crucial to modeling of the heliosphere and its interactions with the interstellar medium, since the wind ram pressure and its temporal variations are important in understanding the distance to the termination shock and heliopause and how those boundaries might vary in time. We focus on results since Solar Wind 7. Among the issues we will discuss are: (1) the time scales for and statistical properties of variations in the ram pressure in the outer heliosphere, and how those variations might affect the morphology of the heliospheric/interstellar medium interface; (2) the question of possible solar wind slowing in the outer heliosphere due to the pick-up of interstellar ions; (3) the issue of whether there is bulk heating of the solar wind associated either with interstellar ion pick-up or with continued heating due to stream-stream interactions; (4) evidence for latitudinal variations in solar wind properties; and (5) the 1.3 year periodicities apparent in the outer heliosphere, and the close correspondence with similar variations seen with inner heliospheric probes.

  5. 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...

  6. Magnetosphere of the outer planets

    NASA Technical Reports Server (NTRS)

    Kennel, C. F.

    1972-01-01

    Scaling laws for possible outer planet magnetospheres are derived. These suggest that convection and its associated auroral effects will play a relatively smaller role than at earth, and that there is a possibility that they could have significant radiation belts of energetic trapped particles.

  7. Session: Hard Rock Penetration

    SciTech Connect

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

    1992-01-01

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

  8. Hardness Tester for Polyur

    NASA Technical Reports Server (NTRS)

    Hauser, D. L.; Buras, D. F.; Corbin, J. M.

    1987-01-01

    Rubber-hardness tester modified for use on rigid polyurethane foam. Provides objective basis for evaluation of improvements in foam manufacturing and inspection. Typical acceptance criterion requires minimum hardness reading of 80 on modified tester. With adequate correlation tests, modified tester used to measure indirectly tensile and compressive strengths of foam.

  9. The hard metal diseases

    SciTech Connect

    Cugell, D.W. )

    1992-06-01

    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.

  10. Strategy for exploration of the outer planets: 1986-1996

    NASA Technical Reports Server (NTRS)

    1986-01-01

    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.

  11. Turbine airfoil with a compliant outer wall

    DOEpatents

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

    2012-04-03

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

  12. Endoliths in Lithophaga lithophaga shells--Variation in intensity of infestation and species occurrence.

    PubMed

    Peharda, Melita; Calcinai, Barbara; Puljas, Sanja; Golubi?, Stjepko; Arapov, Jasna; Thbault, Julien

    2015-07-01

    Pronounced differences with respect to the extent of infestation and the degree of Lithophaga lithophaga shell damage inflicted by euendolithic taxa at two sites in the Adriatic Sea representing different productivity conditions, are described. Shells collected from the eastern part of Katela Bay, which is characterized by higher primary productivity, have significantly more shell damage then the shell collected from a site on the outer coast of the island of ?iovo exposed to the oligotrophic Adriatic Sea. The presence of endoliths and their perforations were detected in different layers of the shell, including solidly mineralized parts of the skeleton and within the organic lamellae incorporated into the shell. Phototrophic endoliths were not observed in the specimens. The most serious damage to L.lithophaga shells was the boring clionaid sponge Pione vastifica, which was more common in shells collected from Katela. PMID:25982321

  13. Photoionization of two-shell endohedral atoms

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

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

  14. Hollow Pollen Shells to Enhance Drug Delivery

    PubMed Central

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

    2014-01-01

    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

  15. New polymer target-shell properties and characterizations. Appendix A

    SciTech Connect

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

    1993-12-31

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

  16. Origin of Outer Solar System

    NASA Technical Reports Server (NTRS)

    Holman, Matthew J.; Boyce, J. (Technical Monitor)

    2003-01-01

    We feel that at the present moment the available theoretical models of the Kuiper belt are still in advance of the data, and thus our main task has been to conduct observational work guided by theoretical motivations. Our efforts over the past year can be divided into four categories: A) Wide-field Searches for Kuiper Belt Objects; B) Pencil-beam Searches for Kuiper Belt Objects; C) Wide-field Searches for Moons of the Outer Planets; D) Pencil-beam Searches for Faint Uranian and Neptunian Moons; E) Recovery Observations. As of April 2002, we have conducted several searches for Kuiper belt objects using large-format mosaic CCD camera on 4-meter class telescopes. In May 1999, we used the Kitt Peak 4-meter with the NOAO Mosaic camera we attempted a search for KBOs at a range of ecliptic latitudes. In addition to our wide-field searches, we have conducted three 'pencil-beam' searches in the past year. In a pencil-beam search we take repeated integrations of the same field throughout a night. After preprocessing the resulting images we shift and recombine them along a range of rates and directions consistent with the motion of KBOs. Stationary objects then smear out, while objects moving at near the shift rate appear as point sources. In addition to our searches for Kuiper belt objects, we are completing the inventory of the outer solar system by search for faint satellites of the outer planets. In August 2001 we conducted pencil beam searches for faint Uranian and Neptunian satellites at CFHT and CTIO. These searches resulted in the discover of two Neptunian and four Uranian satellite candidates. The discovery of Kuiper belt objects and outer planet satellites is of little use if the discoveries are not followed by systematic, repeated astrometric observations that permit reliable estimates of their orbits.

  17. Physics of the outer heliosphere

    SciTech Connect

    Gazis, P.R. )

    1991-01-01

    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.

  18. Advances in the Manufacture of Omega-scale Double-shell Targets

    NASA Astrophysics Data System (ADS)

    Bono, M.

    2005-10-01

    The double-shell ignition target design consists of a low-Z outer shell that absorbs hohlraum-generated x-rays, implodes, and collides with a high-Z inner shell containing DT fuel. Efforts are continuing to field scaled ignition-like double shells on the Omega laser facility over a range of inner-shell Z. Previous ignition-like double-shell implosions on Omega used a low-Z CH inner shell [1]. The current target contains a higher-Z glass inner shell of diameter 216 microns, which is supported by SiO2 aerogel inside a Br-doped CH ablator shell of diameter 550 microns. Fielding double-shell targets has historically been limited by the ability to successfully fabricate them, but several technological advances have recently been made in the manufacturing process. The inner capsule will be cast in SiO2 aerogel of density 50 mg/cc, whose outer contour will be machined concentric to the inner capsule. This piece will then be assembled between two hemispherical ablator shells that mate at a step-joint with an adhesive-filled gap of thickness 100 nm. Three-dimensional tomographs made of each target using an x-ray micro-tomography system will allow precise characterization of the targets. [1] P. Amendt et al., Phys. Rev. Lett. 94, 065004 (2005).

  19. Defects in liquid crystal nematic shells

    NASA Astrophysics Data System (ADS)

    Fernandez-Nieves, A.; Utada, A. S.; Vitelli, V.; Link, D. R.; Nelson, D. R.; Weitz, D. A.

    2006-03-01

    We generate water/liquid crystal (LC)/water double emulsions via recent micro-capillary fluidic devices [A. S. Utada, et.al. Science 308, 537 (2005)]. The resultant objects are stabilized against coalescence by using surfactants or adequate polymers; these also fix the boundary conditions for the director field n. We use 4-pentyl-4-cyanobiphenyl (5CB) and impose tangential boundary conditions at both water/LC interfaces by having polyvinyl alcohol (PVA) dispersed in the inner and outer water phases. We confirm recent predictions [D. R. Nelson, NanoLetters 2, 1125 (2002)] and find that four strength s=+1/2 defects are present; this is in contrast to the two s=+1 defect bipolar configuration observed for bulk spheres [A. Fernandez-Nieves, et.al. Phys. Rev. Lett. 92, 105503 (2004)]. However, these defects do not lie in the vertices of a tetrahedron but are pushed towards each other until certain equilibration distance is reached. In addition to the four defect shells, we observe shells with two s=+1 defects and even with three defects, a s=+1 and two s=+1/2. We argue these configurations arise from nematic bulk distortions that become important as the shell thickness increases. Finally, by adding a different surfactant, sodium dodecyl sulphate (SDS), to the outer phase, we can change the director boundary conditions at the outermost interface from parallel to homeotropic, to induce coalescing of the two pair of defects in the four defect shell configuration to yield two defect bipolar shells.

  20. Organizing Your Hard Disk.

    ERIC Educational Resources Information Center

    Stocker, H. Robert; Hilton, Thomas S. E.

    1991-01-01

    Suggests strategies that make hard disk organization easy and efficient, such as making, changing, and removing directories; grouping files by subject; naming files effectively; backing up efficiently; and using PATH. (JOW)

  1. Fabrication of sub-micrometer-sized jingle bell-shaped hollow spheres from multilayered core-shell particles.

    PubMed

    Gu, Shunchao; Kondo, Tomohiro; Mine, Eiichi; Nagao, Daisuke; Kobayashi, Yoshio; Konno, Mikio

    2004-11-01

    Jingle bell-shaped hollow spheres were fabricated starting from multilayered particles composed of a silica core, a polystyrene inner shell, and a titania outer shell. Composite particles of silica core-polystyrene shell, synthesized by coating a 339-nm-sized silica core with a polystyrene shell of thickness 238 nm in emulsion polymerization, were used as core particles for a succeeding titania-coating. A sol-gel method was employed to form the titania outer shell with a thickness of 37 nm. The inner polystyrene shell in the multilayered particles was removed by immersing them in tetrahydrofuran. These successive procedures could produce jingle bell-shaped hollow spheres that contained a silica core in the titania shell. PMID:15380440

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

    NASA Technical Reports Server (NTRS)

    Draayer, Jerry P.; Troltenier, D.

    1995-01-01

    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.

  3. Shell Worlds: The Question of Shell Stability

    NASA Astrophysics Data System (ADS)

    Roy, K. L.; Kennedy, R. G., III; Fields, D. E.

    The initial idea of shell worlds was first proposed in the January 2009 edition of JBIS. In that paper the stability of the shell around a central world was not discussed at any length except to say that it was stable due to forces induced by gravity. This paper demonstrates in a qualitative and quantitative manner that a material shell supported by atmospheric pressure around a moon or small planet is indeed stable and does not require active measures to remain centered, provided that the central body is large enough. The minimal size of the central body to provide this stability is discussed.

  4. The Development of Hard-X-Ray Optics at MSFC

    NASA Technical Reports Server (NTRS)

    Ramsey, Brian D.; Elsner, R. F.; Engelhaupt, D. E.; Kolodziejczak, J. J.; ODell, S. L.; Speegle, C. O.; Weisskopf, M. C.; Six, Frank (Technical Monitor)

    2002-01-01

    We are fabricating optics for the hard-x-ray region using electroless nickel replication. The attraction of this process, which has been widely used elsewhere, is that the resulting full shell optics are inherently table and thus can have very good angular resolution. The challenge with this process is to develop lightweight optics (nickel has a relatively high density of 8.9 g / cu cm), and to keep down the costs of mandrel fabrication. We accomplished the former through the development of high-strength nickel alloys that permit very thin 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 (high energy replicated optics) 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 and other hard-x-ray optics will be reviewed.

  5. Convection electric field effects on outer radiation belt electron precipitation

    NASA Technical Reports Server (NTRS)

    Gelpi, C.; Benbrook, J. R.; Sheldon, W. R.

    1986-01-01

    A model is presented for the possible diurnal modulation of outer radiation belt electron precipitation by considering the effect of the convection electric field on geomagnetically trapped electrons. The modulation flux is the flux due to electrons in the drift loss cone, i.e., those which drift into the bounce loss cone. The electron flux in the drift loss cone is related to the time allowable for diffusion from the stably trapped population to the drift loss cone for precipitation at a specific geographic location. This time, which is termed the maximum L-shell lifetime, is obtained by computing electron trajectories, using a realistic magnetic field model and a simple model for the electric field. The maximum L-shell lifetimes are taken to be the times between successive entries into the bounce loss cone. Conservation of the first two adiabatic invariants, as electrons are slowly energized by the convection electric field, leads to variations in pitch angle, maximum L-shell lifetimes, and, consequently, to changes in the electron flux in the drift loss cone. These results are compared with observations of precipitating electrons made with sounding rocket payloads.

  6. Outer scale of atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Lukin, Vladimir P.

    2005-10-01

    In the early 70's, the scientists in Italy (A.Consortini, M.Bertolotti, L.Ronchi), USA (R.Buser, Ochs, S.Clifford) and USSR (V.Pokasov, V.Lukin) almost simultaneously discovered the phenomenon of deviation from the power law and the effect of saturation for the structure phase function. During a period of 35 years we have performed successively the investigations of the effect of low-frequency spectral range of atmospheric turbulence on the optical characteristics. The influence of the turbulence models as well as a outer scale of turbulence on the characteristics of telescopes and systems of laser beam formations has been determined too.

  7. Magnetospheres of the outer planets

    SciTech Connect

    Cheng, A.F.

    1986-12-01

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

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

    SciTech Connect

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

    2014-03-21

    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.

  9. Exchange coupled SrFe12O19/Fe-Co core/shell particles with different shell thickness

    NASA Astrophysics Data System (ADS)

    Xu, Xia; Hong, Yang-Ki; Park, Jihoon; Lee, Woncheol; Lane, Alan M.

    2015-11-01

    SrFe12O19/Fe-Co core/shell particles with different shell thickness were synthesized by polyol reduction of Fe and Co ions at 180C with SrFe12O19 particles dispersed in solvent. The core/shell structure is formed by magnetic self-assembly due to the remanent magnetization of SrFe12O19 particles. Within a limited concentration range, the shell thickness could be controlled by regulating the concentration of Fe and Co ions. Core/shell structured SrFe12O19/Fe-Co particles showed more effective exchange coupling effects between hard and soft phases than physically mixed SrFe12O19 and Fe-Co particles. [Figure not available: see fulltext.

  10. Fluctuating shells under pressure

    PubMed Central

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

    2012-01-01

    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

  11. Yolk/shell nanoparticles: classifications, synthesis, properties, and applications

    NASA Astrophysics Data System (ADS)

    Purbia, Rahul; Paria, Santanu

    2015-11-01

    Core/shell nanoparticles were first reported in the early 1990s with a simple spherical core and shell structure, but the area is gradually diversifying in multiple directions such as different shapes, multishells, yolk/shell etc., because of the development of different new properties of the materials, which are useful for several advanced applications. Among different sub-areas of core/shell nanoparticles, yolk/shell nanoparticles (YS NPs) have drawn significant attention in recent years because of their unique properties such as low density, large surface area, ease of interior core functionalization, a good molecular loading capacity in the void space, tunable interstitial void space, and a hollow outer shell. The YS NPs have better properties over simple core/shell or hollow NPs in various fields including biomedical, catalysis, sensors, lithium batteries, adsorbents, DSSCs, microwave absorbers etc., mainly because of the presence of free void space, porous hollow shell, and free core surface. This review presents an extensive classification of YS NPs based on their structures and types of materials, along with synthesis strategies, properties, and applications with which one would be able to draw a complete picture of this area.

  12. Yolk/shell nanoparticles: classifications, synthesis, properties, and applications.

    PubMed

    Purbia, Rahul; Paria, Santanu

    2015-12-21

    Core/shell nanoparticles were first reported in the early 1990s with a simple spherical core and shell structure, but the area is gradually diversifying in multiple directions such as different shapes, multishells, yolk/shell etc., because of the development of different new properties of the materials, which are useful for several advanced applications. Among different sub-areas of core/shell nanoparticles, yolk/shell nanoparticles (YS NPs) have drawn significant attention in recent years because of their unique properties such as low density, large surface area, ease of interior core functionalization, a good molecular loading capacity in the void space, tunable interstitial void space, and a hollow outer shell. The YS NPs have better properties over simple core/shell or hollow NPs in various fields including biomedical, catalysis, sensors, lithium batteries, adsorbents, DSSCs, microwave absorbers etc., mainly because of the presence of free void space, porous hollow shell, and free core surface. This review presents an extensive classification of YS NPs based on their structures and types of materials, along with synthesis strategies, properties, and applications with which one would be able to draw a complete picture of this area. PMID:26567966

  13. Hard superconducting nitrides

    PubMed Central

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

    2005-01-01

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

  14. Spitzer/IRAC Near-Infrared Features in the Outer Parts of S4G Galaxies

    NASA Astrophysics Data System (ADS)

    Laine, Seppo J.; S4G Team

    2013-01-01

    We have visually classified the outer regions of galaxies in the Spitzer Survey of Stellar Structure in Galaxies (S4G), concentrating on features such as asymmetries, extensions, tidal tails, warps, polar rings and shells. We also noted obvious interactions, mergers and companion galaxies. We give statistics of these features and compare the asymmetry estimates to those found by more quantitative methods. We find a strong increase in the fraction of asymmetries towards late T-types. We speculate on the connection between the fraction of outer disk asymmetries and the frequency of interactions during the lifetime of these galaxies.

  15. Replicated Nickel Optics for the Hard-X-Ray Region

    NASA Technical Reports Server (NTRS)

    Ramsey, Brian

    2005-01-01

    Replicated nickel optics has been used extensively in x-ray astronomy, most notable for the XMM/Newton mission. Thc combination of relative ease of fabrication and the inherent stability of full shell optics, make them FIJI attractive approach for medium-resolution, high-throughput applications. MSFC has been developing these optics for use in the hard-x-ray region. Efforts at improving the resolution of these, particularly the very-thin shells required to meet thc weight budget of future missions, will be described together with the prospects for significant improvements down to the 5-arcsec level.

  16. Global storm time depletion of the outer electron belt

    NASA Astrophysics Data System (ADS)

    Ukhorskiy, A. Y.; Sitnov, M. I.; Millan, R. M.; Kress, B. T.; Fennell, J. F.; Claudepierre, S. G.; Barnes, R. J.

    2015-04-01

    The outer radiation belt consists of relativistic (>0.5 MeV) electrons trapped on closed trajectories around Earth where the magnetic field is nearly dipolar. During increased geomagnetic activity, electron intensities in the belt can vary by orders of magnitude at different spatial and temporal scales. The main phase of geomagnetic storms often produces deep depletions of electron intensities over broad regions of the outer belt. Previous studies identified three possible processes that can contribute to the main-phase depletions: adiabatic inflation of electron drift orbits caused by the ring current growth, electron loss into the atmosphere, and electron escape through the magnetopause boundary. In this paper we investigate the relative importance of the adiabatic effect and magnetopause loss to the rapid depletion of the outer belt observed at the Van Allen Probes spacecraft during the main phase of 17 March 2013 storm. The intensities of >1 MeV electrons were depleted by more than an order of magnitude over the entire radial extent of the belt in less than 6 h after the sudden storm commencement. For the analysis we used three-dimensional test particle simulations of global evolution of the outer belt in the Tsyganenko-Sitnov (TS07D) magnetic field model with an inductive electric field. Comparison of the simulation results with electron measurements from the Magnetic Electron Ion Spectrometer experiment shows that magnetopause loss accounts for most of the observed depletion at L>5, while at lower L shells the depletion is adiabatic. Both magnetopause loss and the adiabatic effect are controlled by the change in global configuration of the magnetic field due to storm time development of the ring current; a simulation of electron evolution without a ring current produces a much weaker depletion.

  17. Effect of milling time and CNT concentration on hardness of CNT/Al{sub 2024} composites produced by mechanical alloying

    SciTech Connect

    Perez-Bustamante, R.; Perez-Bustamante, F.; Estrada-Guel, I.; Licea-Jimenez, L.; Miki-Yoshida, M.; Martinez-Sanchez, R.

    2013-01-15

    Carbon nanotube/2024 aluminum alloy (CNT/Al{sub 2024}) composites were fabricated with a combination of mechanical alloying (MA) and powder metallurgy routes. Composites were microstructurally and mechanically evaluated at sintering condition. A homogeneous dispersion of CNTs in the Al matrix was observed by a field emission scanning electron microscopy. High-resolution transmission electron microscopy confirmed not only the presence of well dispersed CNTs but also needle-like shape aluminum carbide (Al{sub 4}C{sub 3}) crystals in the Al matrix. The formation of Al{sub 4}C{sub 3} was suggested as the interaction between the outer shells of CNTs and the Al matrix during MA process in which crystallization took place after the sintering process. The mechanical behavior of composites was evaluated by Vickers microhardness measurements indicating a significant improvement in hardness as function of the CNT content. This improvement was associated to a homogeneous dispersion of CNTs and the presence of Al{sub 4}C{sub 3} in the aluminum alloy matrix. - Highlights: Black-Right-Pointing-Pointer The 2024 aluminum alloy was reinforced by CNTs by mechanical alloying process. Black-Right-Pointing-Pointer Composites were microstructural and mechanically evaluated after sintering condition. Black-Right-Pointing-Pointer The greater the CNT concentration, the greater the hardness of the composites. Black-Right-Pointing-Pointer Higher hardness in composites is achieved at 20 h of milling. Black-Right-Pointing-Pointer The formation of Al{sub 4}C{sub 3} does not present a direct relationship with the milling time.

  18. The Dynamo Bifurcation in Rotating Spherical Shells

    NASA Astrophysics Data System (ADS)

    Morin, Vincent; Dormy, Emmanuel

    We investigate the nature of the dynamo bifurcation in a configuration applicable to the Earth's liquid outer core, i.e. in a rotating spherical shell with thermally driven motions. We show that the nature of the bifurcation, which can be either supercritical or subcritical or even take the form of isola (or detached lobes) strongly depends on the parameters. This dependence is described in a range of parameters numerically accessible (which unfortunately remains remote from geophysical application), and we show how the magnetic Prandtl number and the Ekman number control these transitions.

  19. Imperfection Insensitive Thin Shells

    NASA Astrophysics Data System (ADS)

    Ning, Xin

    The buckling of axially compressed cylindrical shells and externally pressurized spherical shells is extremely sensitive to even very small geometric imperfections. In practice this issue is addressed by either using overly conservative knockdown factors, while keeping perfect axial or spherical symmetry, or adding closely and equally spaced stiffeners on shell surface. The influence of imperfection-sensitivity is mitigated, but the shells designed from these approaches are either too heavy or very expensive and are still sensitive to imperfections. Despite their drawbacks, these approaches have been used for more than half a century. This thesis proposes a novel method to design imperfection-insensitive cylindrical shells subject to axial compression. Instead of following the classical paths, focused on axially symmetric or high-order rotationally symmetric cross-sections, the method in this thesis adopts optimal symmetry-breaking wavy cross-sections (wavy shells). The avoidance of imperfection sensitivity is achieved by searching with an evolutionary algorithm for smooth cross-sectional shapes that maximize the minimum among the buckling loads of geometrically perfect and imperfect wavy shells. It is found that the shells designed through this approach can achieve higher critical stresses and knockdown factors than any previously known monocoque cylindrical shells. It is also found that these shells have superior mass efficiency to almost all previously reported stiffened shells. Experimental studies on a design of composite wavy shell obtained through the proposed method are presented in this thesis. A method of making composite wavy shells and a photogrametry technique of measuring full-field geometric imperfections have been developed. Numerical predictions based on the measured geometric imperfections match remarkably well with the experiments. Experimental results confirm that the wavy shells are not sensitive to imperfections and can carry axial compression with superior mass efficiency. An efficient computational method for the buckling analysis of corrugated and stiffened cylindrical shells subject to axial compression has been developed in this thesis. This method modifies the traditional Bloch wave method based on the stiffness matrix method of rotationally periodic structures. A highly efficient algorithm has been developed to implement the modified Bloch wave method. This method is applied in buckling analyses of a series of corrugated composite cylindrical shells and a large-scale orthogonally stiffened aluminum cylindrical shell. Numerical examples show that the modified Bloch wave method can achieve very high accuracy and require much less computational time than linear and nonlinear analyses of detailed full finite element models. This thesis presents parametric studies on a series of externally pressurized pseudo-spherical shells, i.e., polyhedral shells, including icosahedron, geodesic shells, and triambic icosahedra. Several optimization methods have been developed to further improve the performance of pseudo-spherical shells under external pressure. It has been shown that the buckling pressures of the shell designs obtained from the optimizations are much higher than the spherical shells and not sensitive to imperfections.

  20. A surface crack in shells under mixed-mode loading conditions

    NASA Technical Reports Server (NTRS)

    Joseph, P. F.; Erdogan, F.

    1988-01-01

    The present consideration of a shallow shell's surface crack under general loading conditions notes that while the mode I state can be separated, modes II and III remain coupled. A line spring model is developed to formulate the part-through crack problem under mixed-mode conditions, and then to consider a shallow shell of arbitrary curvature having a part-through crack located on the outer or the inner surface of the shell; Reissner's transverse shear theory is used to formulate the problem under the assumption that the shell is subjected to all five moment and stress resultants.

  1. Outer Appearances Can Be Deceiving

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This graph shows the chemical composition of the rock at Gusev Crater dubbed 'Mazatzal' after it was brushed and ground by the Mars Exploration Rover Spirit's rock abrasion tool. The data, taken by the rover's alpha particle X-ray spectrometer over the last few sols, show that the amount of chlorine and sulfur tri-oxide in Mazatzal first increased after brushing, then diminished after grinding. The interior of the rock appears to have the same chemical make-up as other volcanic or basalt rocks studied in the Gusev Crater area ('Adirondack' and 'Humphrey'). Its outer coating or rind, on the other hand, appears to be of a different constitution. Scientists are still puzzling out the implications of these data.

    The larger symbols on the graph represent inferred rock compositions, while the smaller symbols are actual data points. Observations were made at the target dubbed 'New York' on Mazatzal.

  2. Outer planet entry nonequilibrium heating

    NASA Technical Reports Server (NTRS)

    Leibowitz, L. P.; Kuo, T. J.

    1975-01-01

    An analytical tool has been developed which enables the impact of nonequilibrium effects on outer planet entry heating to be estimated. The analysis combines recent shock tube experiments, flow field calculations, and planetary entry trajectory analysis. The thickness of the nonequilibrium layer and its variation around the entry body have been correlated by a reaction flow parameter over a wide range of entry conditions. The influence of nonequilibrium effects on heating during entry into Saturn and Jupiter model atmospheres has been studied and the effect of vehicle size and ballistic coefficient determined. A nonequilibrium layer of significant thickness was found to exist during portions of entry into Saturn and Jupiter warm atmospheres. However, the nonequilibrium layer was found to be thin during the peak heating portions of the trajectory and resulted in reductions in total probe heating of less than 15 per cent.

  3. Aft outer rim seal arrangement

    SciTech Connect

    Lee, Ching-Pang; Tham, Kok-Mun; Schroeder, Eric; Meeroff, Jamie; Miller, Jr., Samuel R; Marra, John J; Campbell, Christian X

    2015-04-28

    An outer rim seal arrangement (10), including: an annular rim (70) centered about a longitudinal axis (30) of a rotor disc (31), extending fore and having a fore-end (72), an outward-facing surface (74), and an inward-facing surface (76); a lower angel wing (62) extending aft from a base of a turbine blade (22) and having an aft end (64) disposed radially inward of the rim inward-facing surface to define a lower angel wing seal gap (80); an upper angel wing (66) extending aft from the turbine blade base and having an aft end (68) disposed radially outward of the rim outward-facing surface to define a upper angel wing seal gap (80, 82); and guide vanes (100) disposed on the rim inward-facing surface in the lower angel wing seal gap. Pumping fins (102) may be disposed on the upper angel wing seal aft end in the upper angel wing seal gap.

  4. CSI: Hard Drive

    ERIC Educational Resources Information Center

    Sturgeon, Julie

    2008-01-01

    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.…

  5. CSI: Hard Drive

    ERIC Educational Resources Information Center

    Sturgeon, Julie

    2008-01-01

    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.

  6. Work Hard. Be Nice

    ERIC Educational Resources Information Center

    Mathews, Jay

    2009-01-01

    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,

  7. Budgeting in Hard Times.

    ERIC Educational Resources Information Center

    Parrino, Frank M.

    2003-01-01

    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)

  8. Running in Hard Times

    ERIC Educational Resources Information Center

    Berry, John N., III

    2009-01-01

    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,…

  9. Running in Hard Times

    ERIC Educational Resources Information Center

    Berry, John N., III

    2009-01-01

    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,

  10. Chemistry of the outer planets

    NASA Technical Reports Server (NTRS)

    Scattergood, Thomas W.

    1992-01-01

    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.

  11. Comparative Study Of Outer Halos Of Planetary Nebula NGC 246, NGC 1501, And NGC 2022

    NASA Astrophysics Data System (ADS)

    Arion, Douglas N.; Finnvik, S.; Troyer, Z.

    2012-01-01

    A number of planetary nebulae exhibit multiple shell structures, including concentric outer halos. Three such nebulae have been studied by obtaining deep images in [O III] to identify linkages between structures observed in the inner nebula and structures found in the outer halos. Three different planetaries were studied - NGC 246, 1501, and 2022, and all exhibit similar morphologies, suggesting similar evolutionary pathways. Of note are jet structures that appear to extend through all of the shell/halo layers, implying that the layers were ejected before the jets. Data were obtained on the 0.9m WIYN telescope at Kitt Peak National Observatory and the 1.52m Kuiper Telescope of the University of Arizona Steward Observatory. This work was supported in part by the Wisconsin Space Grant Consortium and a private bequest from Ms. Linda Staubitz.

  12. Microstructures and mechanical behavior of mollusk shells

    SciTech Connect

    Laraia, V.J.; Heuer, A.H. . Dept. of Materials Science and Engineering)

    1991-03-01

    Biological hard tissues are load-bearing structural materials, composed of a mineral (ceramic) component and an organic (protein) component. The microstructures of three composite designs commonly found in mollusk shells, the nacreous, foliated, and crossed-lamellar structures are discussed. Although all of these can be viewed as laminar composites, differences exist in the morphology, crystal structure, defect microstructure, and spatial organization of the mineral, CaCo{sub 3}. Electron microscopy investigations of these materials reveal a variety of crystallographic defects, the details of which have been used to refine existing models for biomineralization in these tissues. Flexural strengths in four-point bending are on the order of 100 Mpa. Examples of graceful failure'', i.e. stable crack growth in bulk samples, in the crossed-lamellar and foliated structures are reported. Fractography of such specimens reveals that a number of familiar toughening mechanisms operate together to produce this desirable structural flaw tolerance. Even more unusual is the fact that mollusk shells are harder than the native minerals from which they are made The damage zones and the anisotropy of hardness suggest an explanation for the anomalous hardness based on microstructural design rather than on intrinsic hardening of the mineral phase. 27 refs., 15 figs., 2 tabs.

  13. Shell Cracking Strength in Almond (Prunus dulcis [Mill.] D.A. Webb.)and its implication in uses as a value-added product.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Researchers are currently developing new uses for almond shells, an abundant agricultural by-product. While almond varieties are classified by processing facilities as being either hard or soft shelled, shell morphological characteristics and compositional components contribute to the variability p...

  14. Elbow and knee joint for hard space suits

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C.

    1986-01-01

    An elbow or knee joint for a hard space suit or similar usage is formed of three serially connected rigid sections which have truncated spherical configurations. The ends of each section form solid geometric angles, and the sections are interconnected by hermetically sealed ball bearings. The outer two sections are fixed together for rotation in a direction opposite to rotation of the center section. A preferred means to make the outer sections track each other in rotation comprises a rotatable continuous bead chain which engages sockets circumferentially spaced on the facing sides of the outer races of the bearings. The joint has a single pivot point and the bearing axes are always contained in a single plane for any articulation of the joint. Thus flexure of the joint simulates the coplanar flexure of the knee or elbow and is not susceptible to lockup.

  15. Holographic gravitational infall in the hard wall model

    NASA Astrophysics Data System (ADS)

    Craps, Ben; Lindgren, E. J.; Taliotis, Anastasios; Vanhoof, Joris; Zhang, Hongbao

    2014-10-01

    An infalling shell in the hard wall model provides a simple holographic model for energy injection in a confining gauge theory. Depending on its parameters, a scalar shell either collapses into a large black brane, or scatters between the hard wall and the anti-de Sitter boundary. In the scattering regime, we find numerical solutions that keep oscillating for as long as we have followed their evolution, and we provide an analytic argument that shows that a black brane can never be formed. This provides examples of states in infinite-volume field theory that never thermalize. We find that the field theory expectation value of a scalar operator keeps oscillating, with an amplitude that undergoes modulation.

  16. Iridescence color of shells

    NASA Astrophysics Data System (ADS)

    Liu, Yan

    2002-06-01

    Some shells from both salt water and fresh water show the phenomenon of iridescence color. Pearls and mother-of-pearls also display this phenomenon. In the past, the cause of the iridescence color was attributed to interference. A scanning electron microscope (SEM) was used to study the surface structure of the shell of the mollusk Pinctada Margaritifera. There is a groove structure of reflection grating on the surface area in where the iridescence color appears. An optic experiment with a laser obtained a diffraction pattern produced by the reflection grating structure of the shell. The study led to a conclusion that the iridescence color of the shell is caused by diffraction. A SEM image of the shells of an abalone Haliotis Rufescens (red abalone) showed a statistically regularly arranged tile structure that serves as a two-dimensional grating. This grating structure causes the iridescence color of the shell of red abalone. The dominant color of the iridescence of shells is caused by the uneven grating efficiency in the visible wavelength range when a shell functions as a reflection grating. The wavelength of the dominant color should be at or near the wavelength of the maximum efficiency of the grating.

  17. Outer trapped surfaces are dense near MOTSs

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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.

  18. Cohesive Elements for Shells

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  19. Thermodynamics of rotating thin shells in the BTZ spacetime

    NASA Astrophysics Data System (ADS)

    Lemos, Jos P. S.; Lopes, Francisco J.; Minamitsuji, Masato; Rocha, Jorge V.

    2015-09-01

    We investigate the thermodynamic equilibrium states of a rotating thin shell, i.e., a ring, in a (2 +1 )-dimensional spacetime with a negative cosmological constant. The inner and outer regions with respect to the shell are given by the vacuum anti-de Sitter and the rotating Baados-Teitelbom-Zanelli spacetimes, respectively. The first law of thermodynamics on the thin shell, together with three equations of state for the pressure, the local inverse temperature and the thermodynamic angular velocity of the shell, yields the entropy of the shell, which is shown to depend only on its gravitational radii. When the shell is pushed to its own gravitational radius and its temperature is taken to be the Hawking temperature of the corresponding black hole, the entropy of the shell coincides with the Bekenstein-Hawking entropy. In addition, we consider simple anstze for the equations of state, as well as a power-law equation of state where the entropy and the thermodynamic stability conditions can be examined analytically.

  20. Chemical Component and Proteomic Study of the Amphibalanus (= Balanus) amphitrite Shell.

    PubMed

    Zhang, Gen; He, Li-Sheng; Wong, Yue-Him; Xu, Ying; Zhang, Yu; Qian, Pei-Yuan

    2015-01-01

    As typical biofoulers, barnacles possess hard shells and cause serious biofouling problems. In this study, we analyzed the protein component of the barnacle Amphibalanus (= Balanus) amphitrite shell using gel-based proteomics. The results revealed 52 proteins in the A. Amphitrite shell. Among them, 40 proteins were categorized into 11 functional groups based on KOG database, and the remaining 12 proteins were unknown. Besides the known proteins in barnacle shell (SIPC, carbonic anhydrase and acidic acid matrix protein), we also identified chorion peroxidase, C-type lectin-like domains, serine proteases and proteinase inhibitor proteins in the A. Amphitrite shell. The sequences of these proteins were characterized and their potential functions were discussed. Histology and DAPI staining revealed living cells in the shell, which might secrete the shell proteins identified in this study. PMID:26222041

  1. Chemical Component and Proteomic Study of the Amphibalanus (= Balanus) amphitrite Shell

    PubMed Central

    Zhang, Gen; He, Li-sheng; Wong, Yue-Him; Xu, Ying; Zhang, Yu; Qian, Pei-yuan

    2015-01-01

    As typical biofoulers, barnacles possess hard shells and cause serious biofouling problems. In this study, we analyzed the protein component of the barnacle Amphibalanus (= Balanus) amphitrite shell using gel-based proteomics. The results revealed 52 proteins in the A. Amphitrite shell. Among them, 40 proteins were categorized into 11 functional groups based on KOG database, and the remaining 12 proteins were unknown. Besides the known proteins in barnacle shell (SIPC, carbonic anhydrase and acidic acid matrix protein), we also identified chorion peroxidase, C-type lectin-like domains, serine proteases and proteinase inhibitor proteins in the A. Amphitrite shell. The sequences of these proteins were characterized and their potential functions were discussed. Histology and DAPI staining revealed living cells in the shell, which might secrete the shell proteins identified in this study. PMID:26222041

  2. Hard Times Hit Schools

    ERIC Educational Resources Information Center

    McNeil, Michele

    2008-01-01

    Hard-to-grasp dollar amounts are forcing real cuts in K-12 education at a time when the cost of fueling buses and providing school lunches is increasing and the demands of the federal No Child Left Behind Act still loom larger over states and districts. "One of the real challenges is to continue progress in light of the economy," said Gale Gaines,…

  3. SUPER HARD SURFACED POLYMERS

    SciTech Connect

    Mansur, Louis K; Bhattacharya, R; Blau, Peter Julian; Clemons, Art; Eberle, Cliff; Evans, H B; Janke, Christopher James; Jolly, Brian C; Lee, E H; Leonard, Keith J; Trejo, Rosa M; Rivard, John D

    2010-01-01

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

  4. Softeners for hardness removal.

    PubMed

    Shetty, Rashma; Manjunath, N T; Babu, B T Suresh

    2005-10-01

    The depletion of water resources, both surface and subsurface and deterioration of water quality made researchers and policy makers to think of the possible remedies to make water sources potable / wholesome. There is a need to address the problems of hardness and fluoride in subsurface water on priority basis. In this direction, bench scale studies were conducted to evaluate the performance of water softeners. Indepth studies were carried out at University B.D.T College of Engineering, Davangere, Karnataka, to assess the performance of bench scale softeners of D to H ratio 1:2, 1:3, 1:4 in removing hardness of varied concentrations from both synthetic and natural water samples. Studies revealed that irrespective of D to H ratio of softeners, the waters having hardness concentration up to 1000 mg/l can be treated to the same degree (81.68% and above). The findings of regeneration studies and cost economics are also summarized in this paper. PMID:17051915

  5. The photochemistry of carbon-rich circumstellar shells

    NASA Technical Reports Server (NTRS)

    Huggins, P. J.; Glassgold, A. E.

    1982-01-01

    The effect of ambient ultraviolet photons on the chemical structure of carbon-rich, circumstellar envelopes is investigated with a simple formulation of the time-dependent, photochemical rate equations valid for optically thick shells. Molecules injected into the shielded inner envelope are broken down when they reach the outer regions where ambient ultraviolet photons can penetrate. A quantitative description of the abundance variations is obtained for the case of uniform expansion by detailed consideration of the shielding of the radiation by the dust and molecules of the envelope. Representative results are presented to illustrate the role of shielding in defining the extent of molecular envelopes, the formation of C I and C II shells by photodestruction of carbon-bearing molecules, and the development of layered chemical structures from the photobreakup of polyatomic molecules. Photochemistry makes the outer parts of thick, carbon-rich envelopes into complex regions containing radicals, ions, and atoms which are of considerable observational and theoretical interest.

  6. Applications of spherical shells

    NASA Technical Reports Server (NTRS)

    Wang, T. G.

    1985-01-01

    A new technique of producing hollow spheres of many materials at a very rapid rate, at very low cost, and with high reproducibility of shell diameter and wall thickness has been developed. Shells formed of metal or of other solid materials are expected to find numerous technical and industrial applications. For example, metal shells might be used as inertial confinement fusion targets, or as the principal constituents in lightweight structural materials for NASA Space Stations or DOD large antennas and mirrors, or be employed as containers for phase-change heat-storage media, or serve as containers for hazardous materials, or be employed as catalytic surface agents.

  7. Hard-pan soils - Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  8. 76 FR 2919 - Outer Continental Shelf Official Protraction Diagram and Supplemental Official Outer Continental...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-18

    ... Protraction Diagram and Supplemental Official Outer Continental Shelf Block Diagrams AGENCY: Bureau of Ocean... American Datum of 1983 (NAD 83) Outer Continental Shelf Official Protraction Diagram and Supplemental Official Outer Continental Shelf Block Diagrams. SUMMARY: Notice is hereby given that effective with...

  9. 76 FR 54787 - Outer Continental Shelf Official Protraction Diagram, Lease Maps, and Supplemental Official Outer...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-02

    ... Protraction Diagram, Lease Maps, and Supplemental Official Outer Continental Shelf Block Diagrams AGENCY... revised North American Datum of 1927 (NAD 27) Outer Continental Shelf Official Protraction Diagram, Lease Maps, and Supplemental Official Outer Continental Shelf Block Diagrams. SUMMARY: Notice is hereby...

  10. Outer Sphere Adsorption of Pb(II)EDTA on Goethite

    SciTech Connect

    Bargar, John R

    1999-07-16

    FTIR and EXAFS spectroscopic measurements were performed on Pb(II)EDTA adsorbed on goethite as functions of pH (4-6), Pb(II)EDTA concentration (0.11 {micro}M - 72 {micro}M), and ionic strength (16 {micro}M - 0.5M). FTIR measurements show no evidence for carboxylate-Fe(III) bonding or protonation of EDTA at Pb:EDTA = 1:1. Both FTIR and EXAFS measurements suggest that EDTA acts as a hexadentate ligand, with all four of its carboxylate and both amine groups bonded to Pb(II). No evidence was observed for inner-sphere Pb(II)-goethite bonding at Pb:EDTA = 1:1. Hence, the adsorbed complexes should have composition Pb(II)EDTA{sup 2{minus}}. Since substantial uptake of PbEDTA(II){sup 2{minus}} occurred in the samples, we infer that Pb(II)EDTA{sup 2{minus}} adsorbed as outer-sphere complexes and/or as complexes that lose part of their solvation shells and hydrogen bond directly to goethite surface sites. We propose the term ''hydration-sphere'' for the latter type of complexes because they should occupy space in the primary hydration spheres of goethite surface functional groups, and to distinguish this mode of sorption from common structural definitions of inner- and outer-sphere complexes. The similarity of Pb(II) uptake isotherms to those of other divalent metal ions complexed by EDTA suggests that they too adsorb by these mechanisms. The lack of evidence for inner-sphere EDTA-Fe(III) bonding suggests that previously proposed metal-ligand - promoted dissolution mechanisms should be modified, specifically to account for the presence of outer-sphere precursor species.

  11. Records of River Variation in the Shells of Freshwater Bivalves

    NASA Astrophysics Data System (ADS)

    Carroll, M.; Romanek, C.

    2005-12-01

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

  12. Autoprogrammed synthesis of triple-layered Au@Pd@Pt core-shell nanoparticles consisting of a Au@Pd bimetallic core and nanoporous Pt shell.

    PubMed

    Wang, Liang; Yamauchi, Yusuke

    2010-10-01

    Here we report an autoprogrammed synthesis of unique Au@Pd@Pt triple-layered core-shell structured nanoparticles consisting of a Au core, Pd inner layer, and nanoporous Pt outer shell. The proposed synthesis rationally utilizes the temporal separations of the depositions of Au, Pd, and Pt which affords spontaneously step-by-step formation of triple-layered core-shell colloids. The proposed one-step method is unique in its simplicity and is a significant finding for the facile creation of multilayered nanoarchitectures with designed compositions and desired functions. PMID:20831169

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

    NASA Astrophysics Data System (ADS)

    Fairn, A.; Amils, R.

    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 Europa's interior. Mission design will need to incorporate a drill system routine well suited to penetrate the ice shell tens of meters in the thinner areas, allowing to deep subsurface access and sampling. Landing and drilling targets should be selected among the zones where mapping indicates the presence of a thinner ice shell, as it may potentially suggest the existence of nutrient-rich hydrothermal plumes rising from the rocky interior and melting the ice from below, probably creating chaotic terrains [14]. Little-cratered, thin-crust areas would consequently be interpreted as key pacemakers to detect both the ice/ocean interface and the most complex environments under the ice shell. Additionally, drilling processes will be clearly easier in such zones. References: [1] Hoppa, G., et al. Science 285, 1899-1903 (1999). [2] Schenk, P.M. Nature 417, 419-421 (2002). [3] Anderson J.D. et al. Science 276, 1236-1239 (1997). [4] Anderson J.D. et al. Science 281, 2019-2022 (1998). [5] Carr, M.H., et al. Nature 391, 363-365 (1998). [6] Zahnle, K., et al. Icarus 163, 263-289 (2003). [7] Smith, B.A., et al. Science 206, 927-950 (1979). [8] Zahnle, K., et al. Icarus 136, 202-222 (1998). [9] Levison, H.F., et al. Icarus 143, 415-420 (2000). [10] Schenk, P.M. Lunar Planet. Sci. Conf. XXVII, #1137-1138 (1996). [11] Farrar, K.S. & Collins, G.C. Lunar Planet Sci. Conf. XXXIII, #1450 (2002). [12] Greenberg, R., et al. Icarus 141, 263-286 (1999). [13] Ojakangas, G.W. & Stevenson, D.J. Icarus 81, 220-241 (1989). [14] Collins, G.C. & Goodman, J.C. Europa's Icy Shell Conf., #7032 (2004). [15] Tobie, G., et al. J. Geophys. Res. 108, doi: 10.1029/2003JE002099 (2003). [16] Stevenson, D.J. Lunar Planet Sci. Conf. XXXI, #1506 (2000). [17] O'Brien, D.P., et al. Icarus 156, 152-161 (2002). [18] Buck, L., et al. Geophys. Res. Lett. 29, doi: 10.1029/2002GL016171 (2002). [19] Nimmo, F. Icarus in press (2004). [20] Pierazzo, E. and Chyba, C. F. Icarus 157, 120-127 (2002). [21] McCord, T.B. et al. Science 280, 1242-1245 (1998).

  14. Magnetic nanohybrids loaded with bimetal core-shell-shell nanorods for bacteria capture, separation, and near-infrared photothermal treatment.

    PubMed

    Hu, Bo; Wang, Ning; Han, Lu; Chen, Ming-Li; Wang, Jian-Hua

    2015-04-20

    A novel antimicrobial nanohybrid based on near-infrared (NIR) photothermal conversion is designed for bacteria capture, separation, and sterilization (killing). Positively charged magnetic reduced graphene oxide with modification by polyethylenimine (rGO-Fe3 O4 -PEI) is prepared and then loaded with core-shell-shell Au-Ag-Au nanorods to construct the nanohybrid rGO-Fe3 O4 -Au-Ag-Au. NIR laser irradiation melts the outer Au shell and exposes the inner Ag shell, which facilitates controlled release of the silver shell. The nanohybrids combine physical photothermal sterilization as a result of the outer Au shell with the antibacterial effect of the inner Ag shell. In addition, the nanohybrid exhibits high heat conductivity because of the rGO and rapid magnetic-separation capability that is attributable to Fe3 O4 . The nanohybrid provides a significant improvement of bactericidal efficiency with respect to bare Au-Ag-Au nanorods and facilitates the isolation of bacteria from sample matrixes. A concentration of 25 ?g mL(-1) of nanohybrid causes 100 % capture and separation of Escherichia coli O157:H7 (110(8) cfu mL(-1) ) from an aqueous medium in 10 min. In addition, it causes a 22 C temperature rise for the surrounding solution under NIR irradiation (785 nm, 50 mW cm(-2) ) for 10 min. With magnetic separation, 30 ?g mL(-1) of nanohybrid results in a 100 % killing rate for E. coli O157:H7 cells. The facile bacteria separation and photothermal sterilization is potentially feasible for environmental and/or clinical treatment. PMID:25754902

  15. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, T.P.

    1991-11-26

    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.

  16. Hollow spherical shell manufacture

    DOEpatents

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

    1991-01-01

    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.

  17. Hard metal composition

    DOEpatents

    Sheinberg, Haskell (Los Alamos, NM)

    1986-01-01

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

  18. Hard metal composition

    DOEpatents

    Sheinberg, H.

    1983-07-26

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

  19. Double shell liner implosions

    NASA Astrophysics Data System (ADS)

    Sorokin, S. A.; Chaikovsky, S. A.

    1997-05-01

    Experiments on the double shell liner (DSL) implosions with and without an initial axial magnetic were performed on the SNOP-3 pulse generator (1.1 MA, 100 ns). In implosions of a DSL without an initial axial magnetic field, high radial compressions of the inner shell were observed, as in previous experiments with an initial axial magnetic field. Possible mechanisms for the formation of the initial azimuthal magnetic field are discussed.

  20. Shells and Patterns

    ERIC Educational Resources Information Center

    Sutley, Jane

    2009-01-01

    "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

  1. Shells and Patterns

    ERIC Educational Resources Information Center

    Sutley, Jane

    2009-01-01

    "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…

  2. Inferring the State of Tidally-heated Satellite Ice Shells from Global Shape Measurements

    NASA Astrophysics Data System (ADS)

    Nimmo, F.; Thomas, P. C.; Pappalardo, R. T.; Moore, W. B.

    2006-12-01

    Several icy satellites of the outer solar system, notably Europa and Enceladus, are sufficiently tidally heated that they likely possess ice shells overlying oceans. Because tidal heating varies spatially [1], variations in ice shell thickness are likely to occur [2]. Lateral variations in shell thickness will in turn give rise to global topographic variations. The amplitude of this long-wavelength topography is potentially comparable to shape variations due to tidal and rotational stresses [3]. Thus, careful measurement of satellite shapes from limb profiles may be used to infer the nature of shell thickness variations, and thus the state of the ice shell. We demonstrate that limb profiles of Europa give no evidence for lateral shell thickness variations, in contrast to theoretical predictions [2] for a conductive ice shell above liquid water. There are two possible explanations: 1) the ice shell is sufficiently thick (> ~10 km) that lateral shell flow has smoothed out any variations; 2) the shell is heated mainly from below, resulting in a uniform, thin (~3 km) shell. Based on local topography from limb profiles and stereo topography [4] we favour the former explanation: a constant shell thickness rules out isostatic support, and the thin shell model is unable to flexurally support topography with amplitudes of ~1 km. Given sufficiently good limb profiles, a similar analysis may be carried out for Enceladus. Lateral variations in ice shell thickness also affect the tendency of a satellite to reorient itself [5]; thus, reorientation of Enceladus [6] may provide another constraint on the nature of the ice shell there. [1] G. Tobie et al., Icarus 177, 534-549, 2005. [2] Ojakangas and Stevenson, Icarus 81, 220-241, 1989 [3] Murray and Dermott, Solar System Dynamics, 2000 [4] Prockter and Schenk, Icarus 177, 305-326, 2005. [5] Ojakangas and Stevenson, Icarus 81, 242-270, 1989 [6] Nimmo and Pappalardo, Nature 441, 614-616, 2006.

  3. Stress Focusing in Creased Shells

    NASA Astrophysics Data System (ADS)

    Selden, Sarah; Evans, Arthur; Bende, Nakul; Hayward, Ryan; Santangelo, Christian

    2015-03-01

    Upon indentation, thin shells react by localizing strain energy in polygonal structures as opposed to a uniform axisymmetric distribution. While the formation of these localized structures are well-characterized for perfect shells, the introduction of a crease fundamentally changes the nature of the shell deformation. We perform finite element simulations, in tandem with experiments to explore the effect of a creased shell on the energy landscape. We find that the crease induces a new symmetry-breaking localization that does not appear in perfect shells, and we explore the deformation characteristics of the creased shell over a wide range of crease sizes, shell thickness, and crease orientations.

  4. Outer planets and icy satellites

    NASA Technical Reports Server (NTRS)

    Drobyshevski, E. M.

    1991-01-01

    The resources offered by the outer bodies in the Solar System, starting with the main belt asteroids and Jovian System, are not only larger and more diverse but may even be easier to reach than, say, those of Mars. The use of their material, including water and organic matter, depends exclusively on the general strategy of exploration of the Solar System. Of major interest in this respect are the large ice satellites - Titan, Ganymede, and Callisto. Motion through the planetary magnetospheres excites in their ice envelopes megampere currents which, in the presence of rocky, etc., inclusions with electronic conduction should lead to the bulk electrolysis of ice and accumulation in it of 2H2 + O2 in the form of a solid solution. With the concentration of 2H2 + O2 reaching about 15 wt. percent, the solution becomes capable of detonation by a strong meteoritic impact. An explosion of Ganymede's ice envelope about 0.5 By ago could account for the formation of the Trojans and irregular satellites, all known differences between Ganymede and Callisto, and many other things. The explosion of a small icy planet with M approx less than 0.5 Moon created the asteroid belt. Two to three explosions occurred on Io, and two on Europa. The specific features of the longperiod comets close to Saturn's orbit permit dating Titan's envelope explosion as 10,000 yr ago, which produced its thick atmosphere, young Saturn's rings, as well as a reservoir of ice fragments saturated by 2H2 + O2, i.e., cometary nuclei between the orbits of Jupiter and Saturn. Thus these nuclei should contain, besides organic matter, also 2H2 + O2, which could be used for their transportation as well as for fuel for spaceships. Ices of such composition can reside deep inside Deimos, the Trojans, C-asteroids, etc. The danger of a future explosion of Callisto's electrolyzed ices, which would result in a catastrophic bombardment of the Earth by comets, may be high enough to warrant a revision of the priorities and strategy of space exploration.

  5. Hard Metal Disease

    PubMed Central

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

    1962-01-01

    In Great Britain there have been no published reports of respiratory disease occurring amongst workers in the hard metal (tungsten carbide) industry. In this paper the clinical and radiological findings in six cases and the pathological findings in one are described. In two cases physiological studies indicated mild alveolar diffusion defects. Histological examination in a fatal case revealed diffuse pulmonary interstitial fibrosis with marked peribronchial and perivascular fibrosis and bronchial epithelial hyperplasia and metaplasia. Radiological surveys revealed the sporadic occurrence and low incidence of the disease. The alterations in respiratory mechanics which occurred in two workers following a day's exposure to dust are described. Airborne dust concentrations are given. The industrial process is outlined and the literature is reviewed. The toxicity of the metals is discussed, and our findings are compared with those reported from Europe and the United States. We are of the opinion that the changes which we would describe as hard metal disease are caused by the inhalation of dust at work and that the component responsible may be cobalt. Images PMID:13970036

  6. Incorporation of squalene into rod outer segments

    SciTech Connect

    Keller, R.K.; Fliesler, S.J. )

    1990-08-15

    We have reported previously that squalene is the major radiolabeled nonsaponifiable lipid product derived from ({sup 3}H)acetate in short term incubations of frog retinas. In the present study, we demonstrate that newly synthesized squalene is incorporated into rod outer segments under similar in vitro conditions. We show further that squalene is an endogenous constituent of frog rod outer segment membranes; its concentration is approximately 9.5 nmol/mumol of phospholipid or about 9% of the level of cholesterol. Pulse-chase experiments with radiolabeled precursors revealed no metabolism of outer segment squalene to sterols in up to 20 h of chase. Taken together with our previous absolute rate studies, these results suggest that most, if not all, of the squalene synthesized by the frog retina is transported to rod outer segments. Synthesis of protein is not required for squalene transport since puromycin had no effect on squalene incorporation into outer segments. Conversely, inhibition of isoprenoid synthesis with mevinolin had no effect on the incorporation of opsin into the outer segment. These latter results support the conclusion that the de novo synthesis and subsequent intracellular trafficking of opsin and isoprenoid lipids destined for the outer segment occur via independent mechanisms.

  7. A rigid and weathered ice shell on Titan.

    PubMed

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

    2013-08-29

    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

  8. Depletion of the Outer Asteroid Belt

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi; Malhotra, Renu

    1997-01-01

    During the early history of the solar system, it is likely that the outer planets changed their distance from the sun, and hence, their influence on the asteroid belt evolved with time. The gravitational influence of Jupiter and Saturn on the orbital evolution of asteroids in the outer asteroid belt was calculated. The results show that the sweeping of mean motion resonances associated with planetary migration efficiently destabilizes orbits in the outer asteroid belt on a time scale of 10 million years. This mechanism provides an explanation for the observed depletion of asteroids in that region.

  9. Improved Method of Design for Folding Inflatable Shells

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J.

    2009-01-01

    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

  10. Palaeoecology and evolution of marine hard substrate communities

    NASA Astrophysics Data System (ADS)

    Taylor, P. D.; Wilson, M. A.

    2003-07-01

    Marine organisms have occupied hard substrates since the Archaean. Shells, rocks, wood and sedimentary hardgrounds offer relatively stable habitats compared to unconsolidated sediments, but the plants and animals which inhabit them must develop means to gain and defend this premium attachment space. Hard substrate communities are formed by organisms with a variety of strategies for adhering to and/or excavating the substrates they inhabit. While mobile grazers, organically attached and even soft-bodied organisms may leave evidence of their former presence in ancient hard substrate communities, a superior fossil record is left by sessile encrusters with mineralised skeletons and by borers which leave trace fossils. Furthermore, encrusters and borers are preserved in situ, retaining their spatial relationships to one another and to the substrate. Spatial competition, ecological succession, oriented growth, and differential utilisation of exposed vs. hidden substrate surfaces can all be observed or inferred. Hard substrate communities are thus excellent systems with which to study community evolution over hundreds of millions of years. Here we review the research on modern and ancient hard substrate communities, and point to some changes that have affected them over geological time scales. Such changes include a general increase in bioerosion of hard substrates, particularly carbonate surfaces, through the Phanerozoic. This is, at least in part, analogous to the infaunalisation trends seen in soft substrate communities. Encrusting forms show an increase in skeletalisation from the Palaeozoic into the Mesozoic and Cenozoic, which may be a response to increasing levels of predation. Hard substrate communities, considering borers and encrusters together, show a rough increase in tiering through the Phanerozoic which again parallels trends seen in soft substrate communities. This extensive review of the literature on living and fossil hard substrate organisms shows that many opportunities remain for large-scale studies of trends through time at the community and clade levels. Palaeontologists will especially benefit by closer integration of their work with that of neontologists, particularly in aspects of ecology such as larval recruitment, competition and succession.

  11. Shape transformation of bimetallic Au–Pd core–shell nanocubes to multilayered Au–Pd–Au core–shell hexagonal platelets

    DOE PAGESBeta

    Bhattarai, Nabraj; Prozorov, Tanya

    2015-11-05

    Transformation of metallic or bimetallic (BM) nanoparticles (NPs) from one shape to another desired shape is of importance to nanoscience and nanotechnology, where new morphologies of NPs lead to enhancement of their exploitable properties. In this report, we present the shape transformation of Au octahedral NPs to Au–Pd core–shell nanocubes, followed by their transformation to nanostars and finally to multilayered Au–Pd–Au core–shell hexagonal platelets in the presence of T30 DNA. The weaker binding affinity of T30 DNA directs the growth to favor the formation of lower energy {111} facets, changing the morphology from nanocubes to nanostar. The nanostars, exhibiting unusualmore » intermediate morphologies, are comprised two sets of shell layers and have Au core, Pd intermediate shell, and Au outer shell. Similarly, the hexagonal platelets, which also have Au core and inner Pd shell, are encased in an external gold shell. As a result, the formation of multilayered Au–Pd–Au core–shell hexagonal platelets from Au–Pd core–shell nanocubes via the multilayered nanostars is monitored using scanning/transmission electron microscopy analysis.« less

  12. Shape transformation of bimetallic Au–Pd core–shell nanocubes to multilayered Au–Pd–Au core–shell hexagonal platelets

    SciTech Connect

    Bhattarai, Nabraj; Prozorov, Tanya

    2015-11-05

    Transformation of metallic or bimetallic (BM) nanoparticles (NPs) from one shape to another desired shape is of importance to nanoscience and nanotechnology, where new morphologies of NPs lead to enhancement of their exploitable properties. In this report, we present the shape transformation of Au octahedral NPs to Au–Pd core–shell nanocubes, followed by their transformation to nanostars and finally to multilayered Au–Pd–Au core–shell hexagonal platelets in the presence of T30 DNA. The weaker binding affinity of T30 DNA directs the growth to favor the formation of lower energy {111} facets, changing the morphology from nanocubes to nanostar. The nanostars, exhibiting unusual intermediate morphologies, are comprised two sets of shell layers and have Au core, Pd intermediate shell, and Au outer shell. Similarly, the hexagonal platelets, which also have Au core and inner Pd shell, are encased in an external gold shell. As a result, the formation of multilayered Au–Pd–Au core–shell hexagonal platelets from Au–Pd core–shell nanocubes via the multilayered nanostars is monitored using scanning/transmission electron microscopy analysis.

  13. Core–shell diodes for particle detectors

    NASA Astrophysics Data System (ADS)

    Jia, Guobin; Plentz, Jonathan; Höger, Ingmar; Dellith, Jan; Dellith, Andrea; Falk, Fritz

    2016-02-01

    High performance particle detectors are needed for fundamental research in high energy physics in the exploration of the Higgs boson, dark matter, anti-matter, gravitational waves and proof of the standard model, which will extend the understanding of our Universe. Future particle detectors should have ultrahigh radiation hardness, low power consumption, high spatial resolution and fast signal response. Unfortunately, some of these properties are counter-influencing for the conventional silicon drift detectors (SDDs), so that they cannot be optimized simultaneously. In this paper, the main issues of conventional SDDs have been analyzed, and a novel core–shell detector design based on micro- and nano-structures etched into Si-wafers is proposed. It is expected to simultaneously reach ultrahigh radiation hardness, low power consumption, fast signal response and high spatial resolution down to the sub-micrometer range, which will probably meet the requirements for the most powerful particle accelerators in the near future. A prototype core–shell detector was fabricated using modern silicon nanotechnology and the functionality was tested using electron-beam-induced current measurements. Such a high performance detector will open many new applications in extreme radiation environments such as high energy physics, astrophysics, high resolution (bio-) imaging and crystallography, which will push these fields beyond their current boundaries.

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    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.

  15. Energy-dependent dynamics of keV to MeV electrons in the inner zone, outer zone, and slot regions

    NASA Astrophysics Data System (ADS)

    Reeves, Geoffrey D.; Friedel, Reiner H. W.; Larsen, Brian A.; Skoug, Ruth M.; Funsten, Herbert O.; Claudepierre, Seth G.; Fennell, Joseph F.; Turner, Drew L.; Denton, Mick H.; Spence, Harlan E.; Blake, J. Bernard; Baker, Daniel N.

    2016-01-01

    We present observations of the radiation belts from the Helium Oxygen Proton Electron and Magnetic Electron Ion Spectrometer particle detectors on the Van Allen Probes satellites that illustrate the energy dependence and L shell dependence of radiation belt enhancements and decays. We survey events in 2013 and analyze an event on 1 March in more detail. The observations show the following: (a) at all L shells, lower energy electrons are enhanced more often than higher energies; (b) events that fill the slot region are more common at lower energies; (c) enhancements of electrons in the inner zone are more common at lower energies; and (d) even when events do not fully fill the slot region, enhancements at lower energies tend to extend to lower L shells than higher energies. During enhancement events the outer zone extends to lower L shells at lower energies while being confined to higher L shells at higher energies. The inner zone shows the opposite with an outer boundary at higher L shells for lower energies. Both boundaries are nearly straight in log(energy) versus L shell space. At energies below a few 100 keV, radiation belt electron penetration through the slot region into the inner zone is commonplace, but the number and frequency of "slot filling" events decreases with increasing energy. The inner zone is enhanced only at energies that penetrate through the slot. Energy- and L shell-dependent losses (that are consistent with whistler hiss interactions) return the belts to more quiescent conditions.

  16. Outer planet probe engineering model structural tests

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    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.

  17. Formaldehyde in the Far Outer Galaxy

    NASA Astrophysics Data System (ADS)

    Lugo, S. K.; Magnani, L.; Brand, J.; Wouterloot, J. G. A.

    2006-06-01

    We present results from an initial survey of the 212-111 transition of formaldehyde (H2CO) in the Far Outer Galaxy (galactocentric distances, Rg > 16 kpc). Formaldehyde is a key prebiotic molecule; determining the outermost extent of its distribution can be used to set a limit to the Galaxy's "Habitable Zone", the region where conditions for the formation of life are most favorable. We surveyed 67 clouds in the outer Galaxy ranging 12 - 23 kpc in distance from the Galactic Center. Formaldehyde emission at 140.8 GHz was detected from 44 of 67 lines of sight, including 7 clouds at Rg > 20 kpc. Formaldehyde is readily detectable even in the Far Outer Galaxy beyond the edge of the stellar disk. The widespread distribution of H2CO in the Far Outer Galaxy is a positive first step in determining how favorable are conditions in this large region towards the formation of life.

  18. The outer solar system - Perspectives for exobiology

    NASA Technical Reports Server (NTRS)

    Owen, T.

    1974-01-01

    An attempt is made to summarize the current knowledge about the composition and structures of outer planet atmospheres with special emphasis on Jupiter, Saturn, and Titan. The nature of the substances which are responsible for the yellow coloration observed on both Jupiter and Saturn is discussed. The analysis of planetary conditions conducted shows that the outer solar system offers a variety of environments in which natural experiments in prebiotic organic synthesis must be taking place at the present time.

  19. Outer Retinal Tubulation in Degenerative Retinal Disorders

    PubMed Central

    Goldberg, Naomi R.; Greenberg, Jonathan P.; Laud, Ketan; Tsang, Stephen; Freund, K. Bailey

    2013-01-01

    Objective To demonstrate outer retinal tubulation (ORT) in various degenerative retinal disorders. Methods This was a retrospective review of the multimodal imaging of 29 eyes of 15 patients with various retinal dystrophies and inflammatory maculopathies manifesting ORT. The morphologic features of ORT and its evolution over time were analyzed using spectral-domain optical coherence tomography (SD-OCT) data. Results Outer retinal tubulation was identified as round or ovoid structures with hyper-reflective borders in pattern dystrophy (6 eyes), acute zonal occult outer retinopathy (5 eyes), retinitis pigmentosa (4 eyes), Stargardt disease (4 eyes), gyrate atrophy (2 eyes), choroideremia (2 eyes), and various other degenerative conditions. These structures appeared to develop from the invagination of photoreceptors at the junction of intact and atrophic outer retina. During follow-up, the number and distribution of ORT largely remained stable. As zones of atrophy enlarged, the frequency of ORT appeared to increase. The ORT structures were found in fewer than 10% of patients with retinitis pigmentosa, Stargardt, or pattern dystrophy. Conclusion Outer retinal tubulation is found in various degenerative retinal disorders that share in common damage to the outer retina and/or retinal pigment epithelium. The presence of ORT may be in an indicator of underlying disease stage and severity. PMID:23676993

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

    NASA Astrophysics Data System (ADS)

    Norouzi, Saeid; Farhangi, Hassan

    2011-01-01

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

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

    SciTech Connect

    Norouzi, Saeid; Farhangi, Hassan

    2011-01-17

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

  2. Sensational spherical shells

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    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.

  3. First Images from HERO: A Hard-X-Ray Focusing Telescope

    NASA Technical Reports Server (NTRS)

    Ramsey, Brian D.; Alexander, Cheryl D.; Apple, Jeff A.; Benson, Carl M.; Dietz, Kurtis L.; Elsner, Ronald F.; Engelhaupt, Darell E.; Ghosh, Kajal K.; Kolodziejczak, Jeffery J.; ODell, Stephen L.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    We are developing a balloon-borne hard-x-ray telescope that utilizes grazing incidence optics. Termed HERO, for High-Energy Replicated Optics, the instrument will provide unprecented sensitivity in the hard-x-ray region and will achieve milliCrab-level sensitivity in a typical 3-hour balloon-flight observation and 50 microCrab sensitivity on ultra-long-duration flights. A recent proof-of-concept flight, featuring a small number of mirror shells captured the first focused hard-x-ray images of galactic x-ray sources. Full details of the payload, its expected future performance and its recent measurements are provided.

  4. Oyster shell conveyor used to lift shells from the dock ...

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

    Oyster shell conveyor used to lift shells from the dock into the receiving room housed in the 1965 concrete block addition. - J.C. Lore Oyster House, 14430 Solomons Island Road, Solomons, Calvert County, MD

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

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    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.

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

    SciTech Connect

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

    2003-06-01

    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.

  7. Fabrication of a New Type of Double-Shell Target Having a PVA Inner Layer

    SciTech Connect

    Steinman, D.A.; Wallace, R.; Grant, S.; Hoppe, M.C.; Smith, J.N. Jr.

    2004-03-15

    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 Angst 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.

  8. Physical Mechanisms and Scaling Laws of K-Shell Double Photoionization

    SciTech Connect

    Hoszowska, J.; Dousse, J.-Cl.; Berset, M.; Cao, W.; Fennane, K.; Kayser, Y.; Szlachetko, J.; Szlachetko, M.; Kheifets, A. K.; Bray, I.; Kavcic, M.

    2009-02-20

    We report on the photon energy dependence of the K-shell double photoionization (DPI) of Mg, Al, and Si. The DPI cross sections were derived from high-resolution measurements of x-ray spectra following the radiative decay of the K-shell double vacancy states. Our data evince the relative importance of the final-state electron-electron interaction to the DPI. By comparing the double-to-single K-shell photoionization cross-section ratios for neutral atoms with convergent close-coupling calculations for He-like ions, the effect of outer shell electrons on the K-shell DPI process is assessed. Universal scaling of the DPI cross sections with the effective nuclear charge for neutral atoms is revealed.

  9. Overview: Hard Rock Penetration

    SciTech Connect

    Dunn, J.C.

    1992-08-01

    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 drilling fluid outflow was tested extensively during Long Valley drilling. Results show that this meter is rugged, reliable, and can provide useful measurements of small differences in fluid inflow and outflow rates. By providing early indications of fluid gain or loss, improved control of blow-out and lost circulation problems during geothermal drilling can be expected. In the area of downhole tools for lost circulation control, the concept of a downhole injector for injecting a two-component, fast-setting cementitious mud was developed. DOE filed a patent application for this concept during FY 91. The design criteria for a high-temperature potassium, uranium, thorium logging tool featuring a downhole data storage computer were established, and a request for proposals was submitted to tool development companies. The fundamental theory of acoustic telemetry in drill strings was significantly advanced through field experimentation and analysis. A new understanding of energy loss mechanisms was developed.

  10. Overview: Hard Rock Penetration

    SciTech Connect

    Dunn, J.C.

    1992-01-01

    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 drilling fluid outflow was tested extensively during Long Valley drilling. Results show that this meter is rugged, reliable, and can provide useful measurements of small differences in fluid inflow and outflow rates. By providing early indications of fluid gain or loss, improved control of blow-out and lost circulation problems during geothermal drilling can be expected. In the area of downhole tools for lost circulation control, the concept of a downhole injector for injecting a two-component, fast-setting cementitious mud was developed. DOE filed a patent application for this concept during FY 91. The design criteria for a high-temperature potassium, uranium, thorium logging tool featuring a downhole data storage computer were established, and a request for proposals was submitted to tool development companies. The fundamental theory of acoustic telemetry in drill strings was significantly advanced through field experimentation and analysis. A new understanding of energy loss mechanisms was developed.

  11. Overview - Hard Rock Penetration

    SciTech Connect

    Dunn, James C.

    1992-03-24

    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 drilling fluid outflow was tested extensively during Long Valley drilling. Results show that this meter is rugged, reliable, and can provide useful measurements of small differences in fluid inflow and outflow rates. By providing early indications of fluid gain or loss, improved control of blow-out and lost circulation problems during geothermal drilling can be expected. In the area of downhole tools for lost circulation control, the concept of a downhole injector for injecting a two-component, fast-setting cementitious mud was developed. DOE filed a patent application for this concept during FY 91. The design criteria for a high-temperature potassium, uranium, thorium logging tool featuring a downhole data storage computer were established, and a request for proposals was submitted to tool development companies. The fundamental theory of acoustic telemetry in drill strings was significantly advanced through field experimentation and analysis. A new understanding of energy loss mechanisms was developed.

  12. Measuring the Hardness of Minerals

    ERIC Educational Resources Information Center

    Bushby, Jessica

    2005-01-01

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

  13. Shell Creek Summers

    ERIC Educational Resources Information Center

    Seier, Mark; Goedeken, Suzy

    2005-01-01

    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

  14. Snail Shell Science.

    ERIC Educational Resources Information Center

    Matthews, Catherine

    1992-01-01

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

  15. Agreement, Shells, and Focus.

    ERIC Educational Resources Information Center

    Simpson, Andrew; Wu, Zoe

    2002-01-01

    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

  16. Shell Higher Olefins Process.

    ERIC Educational Resources Information Center

    Lutz, E. F.

    1986-01-01

    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)

  17. Shell Creek Summers

    ERIC Educational Resources Information Center

    Seier, Mark; Goedeken, Suzy

    2005-01-01

    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…

  18. Spontaneous Regeneration of Human Photoreceptor Outer Segments

    PubMed Central

    Horton, Jonathan C.; Parker, Alicia B.; Botelho, James V.; Duncan, Jacque L.

    2015-01-01

    Photoreceptors are damaged in many common eye diseases, such as macular degeneration, retinal detachment, and retinitis pigmentosa. The development of methods to promote the repair or replacement of affected photoreceptors is a major goal of vision research. In this context, it would be useful to know whether photoreceptors are capable of undergoing some degree of spontaneous regeneration after injury. We report a subject who lost retinal function in a wide zone around the optic disc, giving rise to massive enlargement of the physiological blind spot. Imaging with an adaptive optics scanning laser ophthalmoscope (AOSLO) showed depletion of cone outer segments in the affected retina. A year later visual function had improved, with shrinkage of the enlarged blind spot. AOSLO imaging showed repopulation of cone outer segments, although their density remained below normal. There was a one-to-one match between sites of formerly missing outer segments and new outer segments that had appeared over the course of the years recovery. This correspondence provided direct morphological evidence that damaged cones are capable, under some circumstances, of generating new outer segments. PMID:26213154

  19. Spontaneous Regeneration of Human Photoreceptor Outer Segments.

    PubMed

    Horton, Jonathan C; Parker, Alicia B; Botelho, James V; Duncan, Jacque L

    2015-01-01

    Photoreceptors are damaged in many common eye diseases, such as macular degeneration, retinal detachment, and retinitis pigmentosa. The development of methods to promote the repair or replacement of affected photoreceptors is a major goal of vision research. In this context, it would be useful to know whether photoreceptors are capable of undergoing some degree of spontaneous regeneration after injury. We report a subject who lost retinal function in a wide zone around the optic disc, giving rise to massive enlargement of the physiological blind spot. Imaging with an adaptive optics scanning laser ophthalmoscope (AOSLO) showed depletion of cone outer segments in the affected retina. A year later visual function had improved, with shrinkage of the enlarged blind spot. AOSLO imaging showed repopulation of cone outer segments, although their density remained below normal. There was a one-to-one match between sites of formerly missing outer segments and new outer segments that had appeared over the course of the year's recovery. This correspondence provided direct morphological evidence that damaged cones are capable, under some circumstances, of generating new outer segments. PMID:26213154

  20. Effect of shells on photoluminescence of aqueous CdTe quantum dots

    SciTech Connect

    Yuan, Zhimin; Yang, Ping

    2013-07-15

    Graphical abstract: Size-tunable CdTe coated with several shells using an aqueous solution synthesis. CdTe/CdS/ZnS quantum dots exhibited high PL efficiency up to 80% which implies the promising applications for biomedical labeling. - Highlights: • CdTe quantum dots were fabricated using an aqueous synthesis. • CdS, ZnS, and CdS/ZnS shells were subsequently deposited on CdTe cores. • Outer ZnS shells provide an efficient confinement of electron and hole inside the QDs. • Inside CdS shells can reduce the strain on the QDs. • Aqueous CdTe/CdS/ZnS QDs exhibited high stability and photoluminescence efficiency of 80%. - Abstract: CdTe cores with various sizes were fabricated in aqueous solutions. Inorganic shells including CdS, ZnS, and CdS/ZnS were subsequently deposited on the cores through a similar aqueous procedure to investigate the effect of shells on the photoluminescence properties of the cores. In the case of CdTe/CdS/ZnS quantum dots, the outer ZnS shell provides an efficient confinement of electron and hole wavefunctions inside the quantum dots, while the middle CdS shell sandwiched between the CdTe core and ZnS shell can be introduced to obviously reduce the strain on the quantum dots because the lattice parameters of CdS is situated at the intermediate-level between those of CdTe and ZnS. In comparison with CdTe/ZnS core–shell quantum dots, the as-prepared water-soluble CdTe/CdS/ZnS quantum dots in our case can exhibit high photochemical stability and photoluminescence efficiency up to 80% in an aqueous solution, which implies the promising applications in the field of biomedical labeling.

  1. HI shells in the Leiden/Argentina/Bonn HI survey

    NASA Astrophysics Data System (ADS)

    Ehlerov, S.; Palou, J.

    2013-02-01

    Aims: We analyse the all-sky Leiden/Argentina/Bonn HI survey, where we identify shells belonging to the Milky Way. Methods: We used an identification method based on the search of continuous regions of a low brightness temperature that are compatible with given properties of HI shells. Results: We found 333 shells in the whole Galaxy. The size distribution of shells in the outer Galaxy is fitted by a power law with the coefficient of 2.6 corresponding to the index 1.8 in the distribution of energy sources. Their surface density decreases exponentially with a scale length of 2.8 kpc. The surface density of shells with radii ?100 pc in the solar neighbourhood is ~4 kpc-2 and the 2D porosity is ~0.7. Tables A.1 and A.2 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/550/A23

  2. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ....2002 Split shell. Split shell means a shell having any crack which is open and conspicuous for a distance of more than one-fourth the circumference of the shell, measured in the direction of the crack....

  3. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ....2002 Split shell. Split shell means a shell having any crack which is open and conspicuous for a distance of more than one-fourth the circumference of the shell, measured in the direction of the crack....

  4. MISTIC: Radiation hard ECRIS

    NASA Astrophysics Data System (ADS)

    Labrecque, F.; Lecesne, N.; Bricault, P.

    2008-10-01

    The ISAC RIB facility at TRIUMF utilizes up to 100 ?A from the 500 MeV H- cyclotron to produce RIB using the isotopic separation on line (ISOL) method. In the moment, we are mainly using a hot surface ion source and a laser ion source to produce our RIB. A FEBIAD ion source has been recently tested at ISAC, but these ion sources are not suitable for gaseous elements like N, O, F, Ne, , A new type of ion source is then necessary. By combining a high frequency electromagnetic wave and a magnetic confinement, the ECRIS [R. Geller, Electron Cyclotron Resonance Ion Source and ECR Plasmas, Institute of Physics Publishing, Bristol, 1996], [1] (electron cyclotron resonance ion source) can produce high energy electrons essential for efficient ionization of those elements. To this end, a prototype ECRIS called MISTIC (monocharged ion source for TRIUMF and ISAC complex) has been built at TRIUMF using a design similar to the one developed at GANIL [GANIL (Grand Acclrateur National d'Ions Lourds), www.ganil.fr], [2] The high level radiation caused by the proximity to the target prevented us to use a conventional ECRIS. To achieve a radiation hard ion source, we used coils instead of permanent magnets to produce the magnetic confinement. Each coil is supplied by 1000 A-15 V power supply. The RF generator cover a frequency range from 2 to 8 GHz giving us all the versatility we need to characterize the ionization of the following elements: He, Ne, Ar, Kr, Xe, C, O, N, F. Isotopes of these elements are involved in star thermonuclear cycles and, consequently, very important for researches in nuclear astrophysics. Measures of efficiency, emittance and ionization time will be performed for each of those elements. Preliminary tests show that MISTIC is very stable over a large range of frequency, magnetic field and pressure.

  5. Grinding tool for making hemispherical bores in hard materials

    DOEpatents

    Duran, E.L.

    1985-04-03

    A grinding tool for forming hemispherical bores in hard materials such as boron carbide. The tool comprises a hemicircular grinding bit, formed of a metal bond diamond matrix, which is mounted transversely on one end of a tubular tool shaft. The bit includes a spherically curved outer edge surface which is the active grinding surface of the tool. Two coolant fluid ports on opposite sides of the bit enable introduction of coolant fluid through the bore of the tool shaft so as to be emitted adjacent the opposite sides of the grinding bit, thereby providing optimum cooling of both the workpiece and the bit.

  6. 76 FR 63654 - Outer Continental Shelf Official Protraction Diagram, Lease Maps, and Supplemental Official Outer...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-13

    ... Enforcement) published a notice in the Federal Register (76 FR 54787) on September 2, 2011, entitled ``OCS... Bureau of Ocean Energy Management Outer Continental Shelf Official Protraction Diagram, Lease Maps, and Supplemental Official Outer Continental Shelf Block Diagrams AGENCY: Bureau of Ocean Energy Management...

  7. MHD processes in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.

    1984-01-01

    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.

  8. Chasing shadows in the outer solar system

    NASA Astrophysics Data System (ADS)

    Bianco, Federica

    The characteristics of the populations of objects that inhabit the outer solar system carry the fingerprint of the processes that governed the formation and evolution of the solar system. Occultation surveys push the limit of observation into the very small and distant outer solar system objects, allowing us to set constraints on the structure of the Kuiper belt, Scattered disk and Sedna populations. I collected, reduced, and analyzed vast datasets looking for occultations of stars by outer solar system objects, both working with the Taiwanese American Occultation Survey (TAOS) collaboration and leading the MMT/Megacam occultation effort. Having found no such events in my data, I was able to place upper limits on the Kuiper belt, scattered disk and Sedna population. These limits and their derivation are described here.

  9. Baseline Microstructural Characterization of Outer 3013 Containers

    SciTech Connect

    Zapp, Phillip E.; Dunn, Kerry A

    2005-07-31

    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.

  10. Ptolemy's treatment of the outer planets

    NASA Astrophysics Data System (ADS)

    Duke, Dennis

    2005-01-01

    The purpose of this paper is to investigate whether for the outer planets Ptolemy followed his otherwise consistent custom of describing a scenario that did not happen as he says, or whether, at least for the outer planets, he left us a more accurate rendition of events. The detailed reconstructions of Ptolemy's calculations that follow show that, at least in the Almagest, Ptolemy is a writer with consistent habits when it comes to observations. We begin by reviewing, with minimal editorial comment, Ptolemy's calculations for each planet.

  11. Hardness variability in commercial technologies

    SciTech Connect

    Shaneyfelt, M.R.; Winokur, P.S.; Meisenheimer, T.L.; Sexton, F.W.; Roeske, S.B.; Knoll, M.G.

    1994-12-01

    The radiation hardness of commercial Floating Gate 256K E{sup 2}PROMs from a single diffusion lot was observed to vary between 5 to 25 krad(Si) when irradiated at a low dose rate of 64 mrad(Si)/s. Additional variations in E{sup 2}PROM hardness were found to depend on bias condition and failure mode (i.e., inability to read or write the memory), as well as the foundry at which the part was manufactured. This variability is related to system requirements, and it is shown that hardness level and variability affect the allowable mode of operation for E{sup 2}PROMs in space applications. The radiation hardness of commercial 1-Mbit CMOS SRAMs from Micron, Hitachi, and Sony irradiated at 147 rad(Si)/s was approximately 12, 13, and 19 krad(Si), respectively. These failure levels appear to be related to increases in leakage current during irradiation. Hardness of SRAMs from each manufacturer varied by less than 20%, but differences between manufacturers are significant. The Qualified Manufacturer`s List approach to radiation hardness assurance is suggested as a way to reduce variability and to improve the hardness level of commercial technologies.

  12. Natural melting within a spherical shell

    NASA Technical Reports Server (NTRS)

    Bahrami, Parviz A.

    1990-01-01

    Fundamental heat transfer experiments were performed on the melting of a phase change medium in a spherical shell. Free expansion of the medium into a void space within the sphere was permitted. A step function temperature jump on the outer shell wall was imposed and the timewise evolution of the melting process and the position of the solid-liquid interface was photographically recorded. Numerical integration of the interface position data yielded information about the melted mass and the energy of melting. It was found that the rate of melting and the heat transfer were significantly affected by the movement of the solid medium to the base of the sphere due to gravity. The energy transfer associated with melting was substantially higher than that predicted by the conduction model. Furthermore, the radio of the measured values of sensible energy in the liquid melt to the energy of melting were nearly proportional to the Stefan number. The experimental results are in agreement with a theory set forth in an earlier paper.

  13. Model Potentials for a C60 Shell

    NASA Astrophysics Data System (ADS)

    Baltenkov, A. S.; Manson, S. T.; Msezane, A. Z.

    2015-05-01

    Radial square wells are commonly used to model the potential effects of the C60 fullerene molecule. The spatial distribution of electric charges forming such a square well potential has been analyzed. It is shown that this potential is created by two concentric spheres with a double layer of charges. This does not seem to be representative of the actual placement of the carbon nuclei in the molecule. A C60 shell potential has been calculated under the more realistic assumption that it is formed by the averaged charge density of neutral carbon atoms. It is further demonstrated that the phenomenological potentials simulating the C60 shell potential belong to a family of potentials with a non-flat bottom and non-parallel inner and outer potential walls. Two possible types of C60 model potentials are proposed and their parameters have been calculated. However, experiment indicated that the potential does have identifiable (parallel) walls. Thus, we are left with something of a conundrum.

  14. Spin-orbit coupling in graphene induced by adatoms with outer-shell p orbitals

    NASA Astrophysics Data System (ADS)

    Brey, Luis

    2015-12-01

    Many of the exotic properties proposed to occur in graphene rely on the possibility of increasing the spin-orbit coupling (SOC). By combining analytical and numerical tight-binding calculations, in this paper we study the SOC induced by heavy adatoms with active electrons living in p orbitals. Depending on the position of the adatoms on graphene, different kinds of SOC appear. Adatoms located in a hollow position induce spin-conserving intrinsiclike SOC, whereas a random distribution of adatoms induces a spin-flipping Rashba-like SOC. The induced SOC is linearly proportional to the adatom concentration, indicating the nonexistent interference effects between different adatoms. By computing the Hall conductivity, we have proven the stability of the topological quantum Hall phases created by the adatoms against inhomogeneous spin-orbit coupling. For the case of Pb adatoms, we find that a concentration of 0.1 adatoms per carbon atom generates SOC's of the order of 40 meV.

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

    SciTech Connect

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

    1982-01-01

    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.

  16. 38 CFR 38.629 - Outer Burial Receptacle Allowance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2014-07-01 2014-07-01 false Outer Burial Receptacle... (CONTINUED) NATIONAL CEMETERIES OF THE DEPARTMENT OF VETERANS AFFAIRS § 38.629 Outer Burial Receptacle Allowance. (a) Definitions—Outer burial receptacle. For purposes of this section, an outer burial...

  17. 38 CFR 38.629 - Outer Burial Receptacle Allowance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2013-07-01 2013-07-01 false Outer Burial Receptacle... (CONTINUED) NATIONAL CEMETERIES OF THE DEPARTMENT OF VETERANS AFFAIRS § 38.629 Outer Burial Receptacle Allowance. (a) Definitions—Outer burial receptacle. For purposes of this section, an outer burial...

  18. 38 CFR 38.629 - Outer Burial Receptacle Allowance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Outer Burial Receptacle... (CONTINUED) NATIONAL CEMETERIES OF THE DEPARTMENT OF VETERANS AFFAIRS § 38.629 Outer Burial Receptacle Allowance. (a) Definitions—Outer burial receptacle. For purposes of this section, an outer burial...

  19. 38 CFR 38.629 - Outer Burial Receptacle Allowance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2011-07-01 2011-07-01 false Outer Burial Receptacle... (CONTINUED) NATIONAL CEMETERIES OF THE DEPARTMENT OF VETERANS AFFAIRS § 38.629 Outer Burial Receptacle Allowance. (a) Definitions—Outer burial receptacle. For purposes of this section, an outer burial...

  20. 38 CFR 38.629 - Outer Burial Receptacle Allowance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2012-07-01 2012-07-01 false Outer Burial Receptacle... (CONTINUED) NATIONAL CEMETERIES OF THE DEPARTMENT OF VETERANS AFFAIRS § 38.629 Outer Burial Receptacle Allowance. (a) Definitions—Outer burial receptacle. For purposes of this section, an outer burial...

  1. Beta Backscatter Measures the Hardness of Rubber

    NASA Technical Reports Server (NTRS)

    Morrissey, E. T.; Roje, F. N.

    1986-01-01

    Nondestructive testing method determines hardness, on Shore scale, of room-temperature-vulcanizing silicone rubber. Measures backscattered beta particles; backscattered radiation count directly proportional to Shore hardness. Test set calibrated with specimen, Shore hardness known from mechanical durometer test. Specimen of unknown hardness tested, and radiation count recorded. Count compared with known sample to find Shore hardness of unknown.

  2. Prevention of the Outer Space Weaponization

    NASA Astrophysics Data System (ADS)

    Zhukov, Gennady P.

    2002-01-01

    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

  3. The processing of materials in outer space

    NASA Technical Reports Server (NTRS)

    Gelles, S. H.; Colling, E. W.

    1977-01-01

    Zero-gravity environment may lead to fabrication of new and improved materials. According to comprehensive study of application of this promising technology to superconducting and electrical contact materials, outer space processing could improve microstructure and homogeneity of many single and multicomponent systems formed from solidification of fluid phases. New structures that are impossible to form terrestrially may also be accessible in space environment.

  4. 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. ...

  5. The magnetospheres of the outer planets

    SciTech Connect

    Mcnutt, R.L., Jr. )

    1991-01-01

    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.

  6. Ground Based Studies of the Outer Planets

    NASA Technical Reports Server (NTRS)

    Trafton, Laurence M.

    2005-01-01

    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.

  7. THE ORBITS OF THE OUTER URANIAN SATELLITES

    SciTech Connect

    Brozovic, M.; Jacobson, R. A.

    2009-04-15

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

  8. Outer membrane protein profiles of Yersinia ruckeri.

    PubMed

    Davies, R L

    1991-01-01

    The outer membrane protein (OMP) profiles of 135 isolates of Yersinia ruckeri, obtained from nine European countries (100 isolates), North America (23 isolates), Australia (six isolates) and South Africa (two isolates), and including four reference strains, were examined by SDS-PAGE. Outer membranes were isolated by selective solubilisation of the cytoplasmic membrane with 0.5% (w/v) sodium N-lauroyl sarcosinate (Sarkosyl). Outer membrane proteins were stable after in vitro passage and there was no variation in OMP profiles due to colony selection. With the exception of a 39.5 kDa peptidoglycan-associated protein there was also no variation at different stages of the growth cycle. The 39.5 kDa protein was not produced during logarithmic growth phase but increased in abundance as the stationary phase progressed. Interstrain variation occurred in the possession of a 36.5 or 38 kDa heat-modifiable protein and in the possession of peptidoglycan-associated proteins in the molecular weight range 36.5 to 40.5 kDa. Based on variation of these proteins five OMP-types, designated OMP-types 1-5, were identified among the 135 isolates examined. Outer membrane protein analysis was demonstrated to be useful in epidemiological studies of Y. ruckeri. PMID:2024435

  9. Shoulder and hip joints for hard space suits and the like

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C.

    1986-01-01

    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.

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

    PubMed

    Deheyn, Dimitri D; Wilson, Nerida G

    2011-07-22

    Some living organisms produce visible light (bioluminescence) for intra- or interspecific visual communication. Here, we describe a remarkable bioluminescent adaptation in the marine snail Hinea brasiliana. This species produces a luminous display in response to mechanical stimulation caused by encounters with other motile organisms. The light is produced from discrete areas on the snail's body beneath the snail's shell, and must thus overcome this structural barrier to be viewed by an external receiver. The diffusion and transmission efficiency of the shell is greater than a commercial diffuser reference material. Most strikingly, the shell, although opaque and pigmented, selectively diffuses the blue-green wavelength of the species bioluminescence. This diffusion generates a luminous display that is enlarged relative to the original light source. This unusual shell thus allows spatially amplified outward transmission of light communication signals from the snail, while allowing the animal to remain safely inside its hard protective shell. PMID:21159673

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

    PubMed Central

    Deheyn, Dimitri D.; Wilson, Nerida G.

    2011-01-01

    Some living organisms produce visible light (bioluminescence) for intra- or interspecific visual communication. Here, we describe a remarkable bioluminescent adaptation in the marine snail Hinea brasiliana. This species produces a luminous display in response to mechanical stimulation caused by encounters with other motile organisms. The light is produced from discrete areas on the snail's body beneath the snail's shell, and must thus overcome this structural barrier to be viewed by an external receiver. The diffusion and transmission efficiency of the shell is greater than a commercial diffuser reference material. Most strikingly, the shell, although opaque and pigmented, selectively diffuses the blue-green wavelength of the species bioluminescence. This diffusion generates a luminous display that is enlarged relative to the original light source. This unusual shell thus allows spatially amplified outward transmission of light communication signals from the snail, while allowing the animal to remain safely inside its hard protective shell. PMID:21159673

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

    NASA Technical Reports Server (NTRS)

    Schenk, Paul M.

    2002-01-01

    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.

  13. Mineralogy of shells from two freshwater snails Belgrandiella fontinalis and B kuesteri.

    PubMed

    Medaković, Davorin; Slapnik, Rajko; Popović, Stanko; Grzeta, Biserka

    2003-01-01

    X-ray powder diffraction (XRD) was used to study the mineral composition of shells of snails Belgrandiella fontinalis and Belgrandiella kuesteri collected from three freshwater springs in northeastern Slovenia. The fractions of aragonite, calcite, dolomite and quartz in particular shells were determined. The analysed shells consisted of two or more distinct inorganic layers. The outer shell layer for both species and all sampling localities contained aragonite. The outer layer of B. fontinalis collected at one locality, also contained a small fraction of calcite ( approximately 1 molar%) besides the dominant aragonite. Calcite was identified in the inner layer(s) of both species (2 to 3 molar%), while quartz was found only in B. kuesteri (5-7 molar%). However, both species sampled at one locality showed the presence of dolomite (approx. 20 molar%) in the inner layer(s). The presence of dolomite in the shells of adult gastropods and even molluscs is unusual. A possible formation mechanism and specific ecological factor that could influence the precipitation of dolomite in the shells of different Belgrandiella species is discussed. PMID:12507615

  14. Influence of the Inner-Shell Architecture on Quantum Yield and Blinking Dynamics in Core/Multishell Quantum Dots.

    PubMed

    Bajwa, Pooja; Gao, Feng; Nguyen, Anh; Omogo, Benard; Heyes, Colin D

    2016-03-01

    Choosing the composition of a shell for QDs is not trivial, as both the band-edge energy offset and interfacial lattice mismatch influence the final optical properties. One way to balance these competing effects is by forming multishells and/or gradient-alloy shells. However, this introduces multiple interfaces, and their relative effects on quantum yield and blinking are not yet fully understood. Here, we undertake a systematic, comparative study of the addition of inner shells of a single component versus gradient-alloy shells of cadmium/zinc chalogenides onto CdSe cores, and then capping with a thin ZnS outer shell to form various core/multishell configurations. We show that architecture of the inner shell between the CdSe core and the outer ZnS shell significantly influences both the quantum yield and blinking dynamics, but that these effects are not correlated-a high ensemble quantum yield doesn't necessarily equate to reduced blinking. Two mathematical models have been proposed to describe the blinking dynamics-the more common power-law model and a more recent multiexponential model. By binning the same data with 1 and 20?ms resolution, we show that the on times can be better described by the multiexponential model, whereas the off times can be better described by the power-law model. We discuss physical mechanisms that might explain this behavior and how it can be affected by the inner-shell architecture. PMID:26693950

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

    NASA Astrophysics Data System (ADS)

    Smyth, Miriam J.

    1989-12-01

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

  16. Hardness-based plasticity and fracture model for quench-hardenable boron steel (22MnB5)

    SciTech Connect

    Greve, L. Medricky, M. Andres, M.; Eller, T. K.

    2013-12-16

    A comprehensive strain hardening and fracture characterization of different grades of boron steel blanks has been performed, providing the foundation for the implementation into the modular material model (MMM) framework developed by Volkswagen Group Research for an explicit crash code. Due to the introduction of hardness-based interpolation rules for the characterized main grades, the hardening and fracture behavior is solely described by the underlying Vickers hardness. In other words, knowledge of the hardness distribution within a hot-formed component is enough to set up the newly developed computational model. The hardness distribution can be easily introduced via an experimentally measured hardness curve or via hardness mapping from a corresponding hot-forming simulation. For industrial application using rather coarse and computationally inexpensive shell element meshes, the user material model has been extended by a necking/post-necking model with reduced mesh-dependency as an additional failure mode. The present paper mainly addresses the necking/post-necking model.

  17. Long-term loss and re-formation of the outer radiation belt

    NASA Astrophysics Data System (ADS)

    Lee, D.-Y.; Shin, D.-K.; Kim, J.-H.; Cho, J.-H.; Kim, K.-C.; Hwang, J. A.; Turner, D. L.; Kim, T. K.; Park, M.-Y.

    2013-06-01

    Earth's outer radiation belt is known to vary often and significantly on various time scales. In this study, we have used the data of various instruments onboard the THEMIS spacecraft to study long-term changes of the outer radiation belt electrons around the year 2009. We find that the entire outer belt became extremely weak for nearly a year and was practically lost a few times, each time lasting ~20 days up to ~2 months, before eventually re-forming. This was revealed at a wide energy range from several tens of keV to up to 719 keV, which was covered by the THEMIS spacecraft measurements. The loss of the outer belt was associated with extremely weak solar wind conditions, i.e., low interplanetary magnetic field magnitude and slow solar wind speed. In particular, this set greatly reduced magnetospheric convection and/or injections for a prolonged time interval, which led to a large expansion of the plasmasphere, even beyond geosynchronous altitude and thus invading the majority of the typical outer belt territory for the same prolonged time interval. Consequently, preexisting electrons inside the plasmasphere had enough time to be lost into the atmosphere gradually over a time scale of several days without being supplied with fresh electrons from the plasma sheet under the same reduced convection and/or injections. Plasmaspheric hiss waves with an amplitude of up to a few tens of pT persisted to exist during the gradual decay periods, implying that they are likely responsible for the continual loss of the electrons inside the plasmasphere. A complete re-formation of the outer belt to full intensity was then realized over an interval of a few months. During the re-formation process, the magnetospheric convection and/or injections increased, which led to a gradual increase of whistler chorus wave activity, contraction of the plasmasphere, and supply of the plasma sheet electrons at high L shells. This set first an outward increasing profile of the phase space density, which eventually developed into a profile with a peak at low L of ~5 over a time scale of 1-2 days. In this latter stage, a local acceleration at low L shells is found to be clearly needed although the radial diffusion process can contribute to some extent, in particular, for particles with a low first adiabatic invariant value.

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

    NASA Technical Reports Server (NTRS)

    Paranicas, C.; Cheng, A. F.

    1994-01-01

    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.

  19. Wrinkling of Pressurized Elastic Shells

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    We study the formation of localized structures formed by the point loading of an internally pressurized elastic shell. While unpressurized shells (such as a ping-pong ball) buckle into polygonal structures, we show that pressurized shells are subject to a wrinkling instability. We study wrinkling in depth, presenting scaling laws for the critical indentation at which wrinkling occurs and the number of wrinkles formed in terms of the internal pressurization and material properties of the shell. These results are validated by numerical simulations. We show that the evolution of the wrinkle length with increasing indentation can be understood for highly pressurized shells from membrane theory. These results suggest that the position and number of wrinkles may be used in combination to give simple methods for the estimation of the mechanical properties of highly pressurized shells.

  20. Non-axisymmetric shear layers in precessing fluid ellipsoidal shells

    NASA Astrophysics Data System (ADS)

    Tilgner, A.

    1999-03-01

    The motion of fluid in a slowly precessing ellipsoidal shell is calculated numerically. A novel spectral method is employed which uses a decomposition in spherical harmonics but enforces boundary conditions on oblate surfaces. Internal shear layers appear in the simulated flows either because the ellipticities of inner and outer boundaries differ, or because Ekman layers break down. The structure of these layers and their orientation with respect to the axis of precession depends on the relative magnitudes of pressure and viscous torques exerted by the boundaries on the fluid.

  1. Resorcinol/formaldehyde foam shell targets for ICF

    SciTech Connect

    Overturf, G.E. III.; Cook, R.; Letts, S.A.; Buckley, S.R.; McClellan, M.R.; Schroen-Carey, D.

    1995-12-01

    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.

  2. Boundary layers of the earth's outer magnetosphere

    NASA Technical Reports Server (NTRS)

    Eastman, T. E.; Frank, L. A.

    1984-01-01

    The magnetospheric boundary layer and the plasma-sheet boundary layer are the primary boundary layers of the earth's outer magnetosphere. Recent satellite observations indicate that they provide for more than 50 percent of the plasma and energy transport in the outer magnetosphere although they constitute less than 5 percent by volume. Relative to the energy density in the source regions, plasma in the magnetospheric boundary layer is predominantly deenergized whereas plasma in the plasma-sheet boundary layer has been accelerated. The reconnection hypothesis continues to provide a useful framework for comparing data sampled in the highly dynamic magnetospheric environment. Observations of 'flux transfer events' and other detailed features near the boundaries have been recently interpreted in terms of nonsteady-state reconnection. Alternative hypotheses are also being investigated. More work needs to be done, both in theory and observation, to determine whether reconnection actually occurs in the magnetosphere and, if so, whether it is important for overall magnetospheric dynamics.

  3. Outer magnetospheric fluctuations and pulsar timing noise

    NASA Technical Reports Server (NTRS)

    Cheng, K. S.

    1987-01-01

    The Cheng, Ho, and Ruderman (1986) outer-magnetosphere gap model was used to investigate the stability of Crab-type outer magnetosphere gaps for pulsars having the parameter (Omega-square B) similar to that of the Crab pulsar. The Lamb, Pines, and Shaham (1978) fluctuating magnetosphere noise model was applied to the Crab pulsar to examine the type of the equation of state that best describes the structure of the neutron star. The noise model was also applied to other pulsars, and the theoretical results were compared with observational data. The results of the comparison are consistent with the stiff equation of state, as suggested by the vortex creep model of the neutron star interior. The timing-noise observations also contribute to the evidence for the existence of superfluid in the core of the neutron star.

  4. Irradiation chemistry in the outer solar system

    NASA Astrophysics Data System (ADS)

    Brown, Michael E.

    2014-11-01

    The dark, reddish tinged surfaces of icy bodies in the outer solar are usually attributed to the long term irradiation of simple hydrocarbons such as methane leading to the loss of hydrogen and the production of long carbon chains. While methane is stable and detected on the most massive bodies in the Kuiper belt, evidence of active irradiation chemistry is scant except for the presence of ethane on methane-rich Makemake and possible detections of ethane on more methane-poor Pluto and Quaoar. We have obtained deep high signal-to-noise spectra of Makemake from 1.5 to 2.5 microns in an attempt to trace the radiation chemistry in the outer solar system beyond the initial ethane formation. We present the first astrophysical detections of solid ethylene, acetylene, and possibly propane -- all expected products of the continued irradiation of methane, and use these species to map the chemical pathway from methane to long-chain hydrocarbons.

  5. Magnetic Reversal of Onion-Like Fe3O4|MnO| ?-Mn2O3 Core|Shell|Shell Nanoparticles

    NASA Astrophysics Data System (ADS)

    Krycka, Kathryn; Borchers, Julie; Laver, Mark; Salazar-Alverez, German; Lopez-Ortega, Alberto; Estrader, Marta; Surinach, Santiago; Baro, Maria; Sort, Jordi; Nogues, Josep; Fm|Afm|Fm Nanoparticles Collaboration

    2013-03-01

    Magnetic nanoparticles offer potential for biomedical and data storage applications, especially with exchange bias to overcome the superparamagnetic limit. Here we study the role of an antiferromagnetic layer sandwiched between a soft ferrimagnetic core and hard ferrimagnetic shell. The nanoparticles studied consist of 3 nm (diameter) Fe3O4 |50-60 nm thick MnO shell |5 nm thick ?-Mn2O3 shell. Small-angle neutron scattering (SANS) probes both structural and magnetic morphology. SANS reveals that during reversal from 5 T to -5 T at 5 K, there is an increase in spins oriented perpendicular to the applied field. As the temperature is increased to 150 K (above the 123 K Nel temperature of MnO) evidence of an enhanced magnetism from within the MnO shell is observed. Finally, the scattering pattern shifts (indicating a change in the relative magnetism as a function of radius) between 5 K and 50 K.

  6. Estimating Gaia's performance for O stars in the Outer Galactic plane using Herschel data

    NASA Astrophysics Data System (ADS)

    Rygl, K. L. J.; Molinari, S.; Prusti, T.; Antoja, T.; Elia, D.; de Bruijne, J.

    2014-07-01

    It is in the less dense Outer Galaxy where Gaia can contribute much to stellar studies of the Galactic Plane. As O stars are by definition young objects, their positions and kinematics can still be related to their formation site and history. O star astrometry will not only be important for studies of high-mass star formation, such as triggered star-formation in shells, but also an interesting complement to the radio maser astrometry of star-forming regions and the structure of spiral arms. With the TLUSTY (Lanz & Hubeny 2013) model atmospheres and the nominal Gaia parallax uncertainty, we estimate the parallax uncertainty for all subtypes of main sequence O stars given a visual extinction. The expected extinction is an important limitation for Gaia's astrometric performance and we estimate the extinction from the column density maps calculated from the Herschel Infrared Galactic Plane survey (Molinari et al. 2010), a thermal cold dust emission survey of unprecedented angular resolution and sensitivity. In the 10∘ strip, taken to represent the first estimate of the average extinction in the Outer Galaxy, we find that most of the visual extinction is less than 10 mag. Only the most dense parts of the clouds have AV > 10 mag. Given these extinctions toward the Outer Galaxy, Gaia will provide accurate (5σ) astrometry for O stars in the Outer Galaxy up to distances of at least 4-6 kpc, which means that Gaia's O star astrometry will be able to transgress the Perseus arm and reach the less-known Outer Arm of the Milky Way (Rygl et al.https://gaia.ub.edu/Twiki/pub/GREATITNFC/ProgramFinalconference/Poster_Rygl%2cK.pdf).

  7. High energy-resolution electron energy-loss spectroscopy study of the dielectric properties of multi-shell nanoparticles.

    PubMed

    Nakahigashi, Naoyuki; Sato, Yohei; Terauchi, Masami; Uehara, Masato

    2014-11-01

    Nanoparticles, which have multi-shell structure, are expected to be stable and high efficient for the light-emitting devices. The efficiency of luminescence is considered to be affected by the multi-shell structure. In order to understand the mechanism of high efficiency luminescence, it is necessary to evaluate the multi-shell structure and dielectric properties from each particle. High energy-resolution electron energy-loss spectroscopy (HR-EELS) based on TEM is a powerful tool for this purpose. By comparing between the experimental and the simulated results, it is possible to evaluate the effect of the size and physical property of each shell material on the dielectric properties of multi-shell nanoparticles. In this study, simulations of EELS spectra of multi-shell nanoparticle (core: CdSe, inner shell: CdS, outer shell: ZnS) and mono-shell nanoparticle (core: CdSe, shell: CdS) were conducted by the dielectric continuum theory[1].Figure1 shows calculated EELS spectra of multi and mono shell nanoparticles. The spectra are calculated from dielectric functions of single CdSe, CdS and ZnS crystals, which were experimentally derived from HR-EELS spectra by using Kramers-Kronig analysis. The radius of 6.9 nm for the nanoparticle in the simulation corresponds to the average size of actual synthesized nanoparticles. Energy positions of arrows in the inset correspond to band gap energies of CdSe, CdS and ZnS[2]. In the spectrum of multi-shell nanoparticle, the intensity corresponding to interband transition near band gap of CdSe is suppressed comparing with that of the mono shell nanoparticle. This result indicates that ZnS outer shell affects the intensity profile of EELS spectrum near band gap. This effect should be sensitive for the thickness of the shells. Thus, there is a possibility that the effect of size and thickness of each core and shell on dielectric properties of multi-shell nanoparticles could be evaluated by using HR-EELS technique.jmicro;63/suppl_1/i18/DFU039F1F1DFU039F1Fig. 1.Calculated EELS spectra. PMID:25359810

  8. Photopolarimetry team outer planets mission definition phase

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The work is reported of the Photopolarimetry Team in identifying scientific objectives for photometer/polarimeter experiments for outer planet flyby missions. A discussion of the scientific objectives which can be attained with a photometer/polarimeter experiment, and summaries of the special studies which were performed for the Photopolarimetry Team are presented along with a description of the photometer/polarimeter design which was developed for the Meteoroid Detection Team.

  9. Planetary protection guidelines for outer planet missions.

    PubMed

    Stabekis, P; DeVincenzi, D L

    1978-01-01

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

  10. A photometric survey of outer belt asteroids

    NASA Technical Reports Server (NTRS)

    Dimartino, M.; Gonano-Beurer, M.; Mottola, Stefano; Neukum, G.

    1992-01-01

    Since 1989, we have been conducting a research program devoted to the study of the Trojans and outer belt asteroids (Hilda and Cybele groups), in order to characterize their rotational properties and shapes. As an outcome of several observational campaigns, we determined rotational periods and lightcurve amplitudes for 23 distant asteroids, using both CCD and photoelectric photometry. In this paper, we compare the rotational properties of main belt asteroids and Trojans, based on the preliminary results of this survey.

  11. Planetary magnetism in the outer solar system.

    NASA Technical Reports Server (NTRS)

    Sonett, C. P.

    1973-01-01

    A brief review of the salient considerations which apply to the existence of magnetic fields in connection with planetary and subplanetary objects in the outer solar system is given. Consideration is given to internal dynamo fields, fields which might originate from interaction with the solar wind or magnetospheres (externally driven dynamos) and lastly fossil magnetic fields such as have been discovered on the moon. Where possible, connection is made between magnetism, means of detection, and internal body properties.

  12. Differential Rotation within the Earth's Outer Core

    NASA Technical Reports Server (NTRS)

    Hide, R.; Boggs, D. H.; Dickey, J. O.

    1998-01-01

    Non-steady differential rotation drive by bouyancy forces within the Earth's liquid outer core (OC) plays a key role not only in the generation of the main geomagnetic field by the magnetohydrodynamic (MHD) dynamo process but also in the excitation of irregular fluctuations in the angular speed of rotation of the overlying solid mantle, as evidenced by changes in the length of the day (LOD) on decadal and longer timescales (1-8).

  13. A model environment for outer zone electrons

    NASA Technical Reports Server (NTRS)

    Singley, G. W.; Vette, J. I.

    1972-01-01

    A brief morphology of outer zone electrons is given to illustrate the nature of the phenomena that we are attempting to model. This is followed by a discussion of the data processing that was done with the various data received from the experimenters before incorporating it into the data base from which this model was ultimately derived. The details of the derivation are given, and several comparisons of the final model with the various experimental measurements are presented.

  14. Cosmic ray gradients in the outer heliosphere

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  15. The structure of circumstellar shells

    NASA Technical Reports Server (NTRS)

    Fix, John D.

    1993-01-01

    This document provides a report on research activities carried out with the support of NASA grant NAG 5-1174, the Structure of Circumstellar Shells, funded under the Astrophysics Data Program. The research carried out with the support of this grant is a study of the properties of circumstellar dust shells for which spectra are available through IRAS low resolution spectrometry (LRS). This research consisted of the development and application of models of axisymmetric circumstellar shells and a preliminary survey of the applicability of neural nets for analysis of the IRAS LRS spectra of circumstellar dust shells.

  16. Influence of interface stabilisers and surrounding aqueous phases on nematic liquid crystal shells.

    PubMed

    Noh, JungHyun; Reguengo De Sousa, Kevin; Lagerwall, Jan P F

    2015-12-23

    We investigate the nematic-isotropic (N-I) transition in shells of the liquid crystal 5CB, surrounded by aqueous phases that conventionally are considered to be immiscible with 5CB. The aqueous phases contain either sodium dodecyl sulfate (SDS) or polyvinyl alcohol (PVA) as stabiliser, the former additionally promoting homeotropic director alignment. For all shell configurations we find a depression of the clearing point compared to pure 5CB, indicating that a non-negligible fraction of the constituents of the surrounding phases enter the shell, predominantly water. In hybrid-aligned shells, with planar outer and homeotropic inner boundary (or vice versa), the N-I transition splits into two steps, with a consequent three-step textural transformation. We explain this as a result of the order-enhancing effect of a monolayer of radially aligned SDS molecules adsorbed at the homeotropic interface. PMID:26512764

  17. Controllable fabrication and magnetic properties of double-shell cobalt oxides hollow particles

    PubMed Central

    Zhang, Dan; Zhu, Jianyu; Zhang, Ning; Liu, Tao; Chen, Limiao; Liu, Xiaohe; Ma, Renzhi; Zhang, Haitao; Qiu, Guanzhou

    2015-01-01

    Double-shell cobalt monoxide (CoO) hollow particles were successfully synthesized by a facile and effective one-pot solution-based synthetic route. The inner architecture and outer structure of the double-shell CoO hollow particles could be readily created through controlling experimental parameters. A possible formation mechanism was proposed based on the experimental results. The current synthetic strategy has good prospects for the future production of other transition-metal oxides particles with hollow interior. Furthermore, double-shell cobalt oxide (Co3O4) hollow particles could also be obtained through calcinating corresponding CoO hollow particles. The magnetic measurements revealed double-shell CoO and Co3O4 hollow particles exhibit ferromagnetic and antiferromagnetic behaviour, respectively. PMID:25736824

  18. Outer membrane proteins of pathogenic spirochetes

    PubMed Central

    Cullen, Paul A.; Haake, David A.; Adler, Ben

    2009-01-01

    Pathogenic spirochetes are the causative agents of several important diseases including syphilis, Lyme disease, leptospirosis, swine dysentery, periodontal disease and some forms of relapsing fever. Spirochetal bacteria possess two membranes and the proteins present in the outer membrane are at the site of interaction with host tissue and the immune system. This review describes the current knowledge in the field of spirochetal outer membrane protein (OMP) biology. What is known concerning biogenesis and structure of OMPs, with particular regard to the atypical signal peptide cleavage sites observed amongst the spirochetes, is discussed. We examine the functions that have been determined for several spirochetal OMPs including those that have been demonstrated to function as adhesins, porins or to have roles in complement resistance. A detailed description of the role of spirochetal OMPs in immunity, including those that stimulate protective immunity or that are involved in antigenic variation, is given. A final section is included which covers experimental considerations in spirochetal outer membrane biology. This section covers contentious issues concerning cellular localization of putative OMPs, including determination of surface exposure. A more detailed knowledge of spirochetal OMP biology will hopefully lead to the design of new vaccines and a better understanding of spirochetal pathogenesis. PMID:15449605

  19. Radio wave scattering in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    1995-01-01

    Current models for the 2-3 kHz emissions observed by the Voyager spacecraft in the outer heliosphere involve 2f(p) radiation generated near the termination shock or the heliopause. Radio wave scattering by solar wind density irregularities strongly affects observed sources of f(p) and 2f(p) emission in the inner heliosphere and the characteristics of astrophysical sources. In particular, the angular size, brightness temperature, and time variability of the source are strongly affected by scattering, thereby having major implications for the inferred size, energy budget, time variability, location, and nature of the source if scattering is ignored. This paper addresses whether scattering is important for interpreting the Voyager 2-3 kHz emissions. Quantitative calculations (with and without diffraction) are performed for the angular broadening of an outer heliospheric source as a function of path length, radiation frequency relative to f(p) and the spectrum of density irregularities. The effects of scattering in both the solar wind and the heliosheath are considered. Predictions for radial gradients in the source's apparent angular size and in the source's modulation index are presented. The calculations are compared with observations and the results discussed. First estimates suggest that scattering plausibly dominates the observed source size. The observed trend in modulation index with heliocentric distance is consistent with scattering being important and the source being in the outer heliosphere. Additional arguments for scattering being important are summarized.

  20. CLOSURE WELD DEVELOPMENT FOR 3013 OUTER CONTAINERS

    SciTech Connect

    Daugherty, W.; Howard, S.; Peterson, K.; Stokes, M.

    2009-11-10

    Excess plutonium materials in the DOE complex are packaged and stored in accordance with DOE-STD-3013. This standard specifies requirements for the stabilization of such materials and subsequent packaging in dual nested seal-welded containers. Austenitic stainless steels have been selected for container fabrication. The inner 3013 container provides contamination control while the outer 3013 container is the primary containment vessel and is the focus of this paper. Each packaging site chose a process for seal welding the outer 3013 containers in accordance with its needs and expertise. The two processes chosen for weld closure were laser beam welding (LBW) and gas tungsten arc welding (GTAW). Following development efforts, each system was qualified in accordance with DOE-STD-3013 prior to production use. The 3013 outer container closure weld joint was designed to accommodate the characteristics of a laser weld. This aspect of the joint design necessitated some innovative process and equipment considerations in the application of the GTAW process. Details of the weld requirements and the development processes are presented and several potential enhancements for the GTAW system are described.

  1. Empirical model of lower band chorus wave distribution in the outer radiation belt

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Accurate modeling of wave-particle interactions in the radiation belts requires detailed information on wave amplitudes and wave-normal angular distributions over L shells, magnetic latitudes, magnetic local times, and for various geomagnetic activity conditions. In this work, we develop a new and comprehensive parametric model of VLF chorus waves amplitudes and obliqueness in the outer radiation belt using statistics of VLF measurements performed in the chorus frequency range during 10 years (2001-2010) aboard the Cluster spacecraft. We used data from the Spatio-Temporal Analysis of Field Fluctuations-Spectrum Analyzer experiment, which spans a total frequency range from 8 Hz to 4 kHz. The statistical model is presented in the form of an analytical function of latitude and Kp (or Dst) index for day and night sectors of the magnetosphere and for two ranges of L shells above the plasmapause, from L = 4 to 5 and from L = 5 to 7. This model can be directly applied for numerical calculations of charged particle pitch angle and energy diffusion coefficients in the outer radiation belt, allowing to study with unprecedented detail their statistical properties as well as their important spatiotemporal variations with geomagnetic activity.

  2. Off-shell supersymmetry

    NASA Astrophysics Data System (ADS)

    Ho, Chiu Man; Okada, Nobuchika

    2015-11-01

    Supersymmetry does not dictate the way we should quantize the fields in the supermultiplets, and so we have the freedom to quantize the Standard Model (SM) particles and their superpartners differently. We propose a generalized quantization scheme under which a particle can only appear off-shell, while its contributions to quantum corrections are exactly the same as those in the usual quantum field theory. We apply this quantization scheme solely to the sparticles in the R-parity preserving Minimal Supersymmetric Standard Model (MSSM). Thus, sparticles can only appear off-shell. They could be light but would completely escape the direct detection at any experiments such as the LHC. However, our theory still retains the same desirable features of the usual MSSM at the quantum level. For instance, the gauge hierarchy problem is solved and the three MSSM gauge couplings are unified in the usual way. Although direct detection of sparticles is impossible, their existence can be revealed by precise measurements of some observables (such as the running QCD coupling) that may receive quantum corrections from them and have sizable deviations from the SM predictions. Also, the experimental constraints from the indirect sparticle search are still applicable.

  3. Automated shell theory for rotating structures (ASTROS)

    NASA Technical Reports Server (NTRS)

    Foster, B. J.; Thomas, J. M.

    1971-01-01

    A computer program for analyzing axisymmetric shells with inertial forces caused by rotation about the shell axis is developed by revising the STARS II shell program. The basic capabilities of the STARS II shell program, such as the treatment of the branched shells, stiffened wall construction, and thermal gradients, are retained.

  4. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hard seed. 201.21 Section 201.21 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.21 Hard seed. The label shall show the percentage of hard seed... percentage of hard seed shall not be included as part of the germination percentage....

  5. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hard seed. 201.21 Section 201.21 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.21 Hard seed. The label shall show the percentage of hard seed... percentage of hard seed shall not be included as part of the germination percentage....

  6. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Hard seed. 201.30 Section 201.30 Agriculture... REGULATIONS Labeling Vegetable Seeds § 201.30 Hard seed. The label shall show the percentage of hard seed, if... percentage of hard seed shall not be included as part of the germination percentage....

  7. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hard seed. 201.30 Section 201.30 Agriculture... REGULATIONS Labeling Vegetable Seeds § 201.30 Hard seed. The label shall show the percentage of hard seed, if... percentage of hard seed shall not be included as part of the germination percentage....

  8. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Hard seed. 201.21 Section 201.21 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.21 Hard seed. The label shall show the percentage of hard seed... percentage of hard seed shall not be included as part of the germination percentage....

  9. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hard seed. 201.30 Section 201.30 Agriculture... REGULATIONS Labeling Vegetable Seeds § 201.30 Hard seed. The label shall show the percentage of hard seed, if... percentage of hard seed shall not be included as part of the germination percentage....

  10. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Hard seed. 201.30 Section 201.30 Agriculture... REGULATIONS Labeling Vegetable Seeds § 201.30 Hard seed. The label shall show the percentage of hard seed, if... percentage of hard seed shall not be included as part of the germination percentage....

  11. 7 CFR 201.30 - Hard seed.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Hard seed. 201.30 Section 201.30 Agriculture... REGULATIONS Labeling Vegetable Seeds § 201.30 Hard seed. The label shall show the percentage of hard seed, if... percentage of hard seed shall not be included as part of the germination percentage....

  12. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Hard seed. 201.21 Section 201.21 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.21 Hard seed. The label shall show the percentage of hard seed... percentage of hard seed shall not be included as part of the germination percentage....

  13. 7 CFR 201.21 - Hard seed.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Hard seed. 201.21 Section 201.21 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.21 Hard seed. The label shall show the percentage of hard seed... percentage of hard seed shall not be included as part of the germination percentage....

  14. The design of mineralised hard tissues for their mechanical functions.

    PubMed

    Currey, J D

    1999-12-01

    Most hard tissues have as their primary purpose to be stiff. Outside the arthropods, mineralisation of a soft organic matrix is the almost universal method of producing high stiffness. However, stiffening brings with it the undesirable mechanical result of brittleness (lack of toughness). The mineralisation of some tissues, such as bone and dentine, can be modified rather easily, in evolutionary terms, to produce the optimum mix of stiffness with bending strength (which, except at the highest mineralisations, go together) on one hand and toughness on the other hand. However, in most other tissues, such as mollusc shell, echinoderm skeleton, brachiopod shell, barnacle shell and enamel, mineralisation is almost all-or-none, and no subtle gradations seem possible. In such cases, other features, such as architecture, must be modified to produce a useful skeleton. Not only the mechanical properties of the skeletal tissue, but its cost, mass and time taken for production will, biologists tend to assume, be balanced by natural selection to produce a satisfactory result. However, such complexity makes it difficult to be sure that we understand the extent to which mineralised skeletal materials are the best possible solution to the problems facing the animals and that we are not just telling 'Just-So' stories. Furthermore, there are some skeletal materials that do not seem to make much sense at the moment, although no doubt all will become clear eventually. PMID:10562511

  15. Magnetic levitation for hard superconductors

    SciTech Connect

    Kordyuk, A.A.

    1998-01-01

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

  16. Hi shells, supershells, shell-like objects, and ''worms''

    SciTech Connect

    Heiles, C.

    1984-08-01

    We present photographic representations of the combination of two Hi surveys, so as to eliminate the survey boundaries at Vertical BarbVertical Bar = 10/sup 0/. We also present high-contrast photographs for particular velocities to exhibit weak Hi features. All of these photographs were used to prepare a new list of Hi shells, supershells, and shell-like objects. We discuss the structure of three shell-like objects that are associated with high-velocity gas, and with gas at all velocities that is associated with radio continuum loops I, II, and III. We use spatial filtering to find wiggly gas filaments: ''worms'': crawling away from the galactic plane in the inner Galaxy. The ''worms'' are probably parts of shells that are open at the top; such shells should be good sources of hot gas for the galactic halo.

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

    PubMed

    Magwene, Paul M; Socha, John J

    2013-02-01

    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

  18. 75 FR 61512 - Outer Continental Shelf Official Protraction Diagrams

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... Protraction Diagrams AGENCY: Bureau of Ocean Energy Management, Regulation and Enforcement, Interior. ACTION... Outer Continental Shelf Official Protraction Diagrams (OPDs) located within Atlantic Ocean areas, with... informational purposes only. Outer Continental Shelf Official Protraction Diagrams in the North Atlantic,...

  19. Dynamic indentation hardness of materials

    NASA Astrophysics Data System (ADS)

    Koeppel, Brian James

    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.

  20. Biomineralisation in Mollusc shells

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    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 m, 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 shells is genetic. However, environmental influences do exist. Due to the complex structures and composition of these shells, localized analyses must be preferred. The role of the composition and distribution of the organic matrix in fossilisation processes, and any potentially induced alterations is not yet known. Mutvei 1970, Biomineralisation 2, 48. Mutvei 1977, Calc. Tiss. Res. 24, 1. Cuif et al.1980, C. R. Acad. Sc. Paris 290, ser. D: 759. Dauphin & Cuif 1999, Ann. Sci. Nat. 2:73. Dauphin & Denis 2000, Comp. Biochem. Physiol. A126: 367. Dauphin 2001, N. Jb. Geol. Palaont. Mh. 2 : 103. Dauphin 2001, Palaont. Zeit. 75, 1: 113. Levi-Kalisman et al. 2001, J. Struct. Biol. 135:8. Dauphin 2002, Comp. Biochem. Physiol. A132, 3: 577. Dauphin et al. 2003, J. Struct. Biol., 142: 272. Gotliv et al. 2003, Chem. Biochem. 4: 522. Gotliv et al. 2004, ChemBioChem. 6:304. Dauphin et al. 2005, Amer. Mineral. 90: 1748. Nudelman et al. 2006, J. Struct. Biol. 153:176. Takeushi & Endo 2006, mar. Biotech. 8: 52. Dauphin 2008, Anal. Bioanal. Chem. 309: 1659. Cuif et al. 2008, Mineral. Mag. 72, 1: 233. This work has been made possible thanks to the support from ANR-06-BLANC-0233-01 project (BIOCRISTAL).

  1. Recent progress in the ground calibration of the ASTRO-H Hard X-ray telescope (HXT-2)

    NASA Astrophysics Data System (ADS)

    Mori, Hideyuki; Kuroda, Yuji; Miyazawa, Takuya; Awaki, Hisamitsu; Babazaki, Yasunori; Furuzawa, Akihiro; Hibino, Tatsuya; Iizuka, Ryo; Ishibashi, Kazunori; Iwase, Toshihiro; Kunieda, Hideyo; Kurihara, Daichi; Matsumoto, Hironori; Miyata, Yusuke; Saji, Shigetaka; Sugita, Satoshi; Suzuki, Yoshio; Tachibana, Sasagu; Tamura, Keisuke; Tawara, Yuzuru; Uesugi, Kentaro

    2014-07-01

    The 6th Japanese X-ray satellite, ASTRO-H, equips two Hard X-ray Telescopes (HXTs) to perform imaging spectroscopy up to 70 keV. The 2nd flight module (HXT-2) had been completed in July, 2013. After some environmental tests were passed, the X-ray performance of the HXT-2 was measured at the SPring-8 BL20B2, 3rd generation synchrotron facility. The angular resolution defined with a Half Power Diameter (HPD) was 1:'9 at 30 keV and 1:'8 at 50 keV. This small energy dependence is considered to be caused by the difference in image quality of each foil; the inner mirror shells have better quality than outer ones. The effective area was found to be 178 cm2 at 30 keV and 82 cm2 at 50 keV, both of which exceed the requirement. Furthermore, the detailed energy dependence of the effective area was examined for a limited aperture in the 30{70 keV band with a pitch of 1 keV. We also measured the off-axis dependence of the effective area at 50 keV, and then determined the optical axis. The field of view of the HXT-2 was found to be 5:'6 (FWHM of the vignetting function), consistent with the simulation. In this paper, we also report the detailed analysis of the ground calibration data, which will be used for image reconstruction by a ray-tracing simulator.

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

    NASA Astrophysics Data System (ADS)

    Kosuge, Toshio

    2002-01-01

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

  3. Foam shell cryogenic ICF target

    DOEpatents

    Darling, Dale H. (Pleasanton, CA)

    1987-01-01

    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.

  4. Shell Observations of Classical Novae

    NASA Astrophysics Data System (ADS)

    Esenoglu, H. H.; Saygac, A. T.

    2014-12-01

    We present shell observations of some classical novae from the Turkish National Observatory. We reobserved them to image their faint shells a long time after their outbursts. We revise the old findings with the new data and we call attention to narrow band pass observations.

  5. Manufacturing Complicated Shells And Liners

    NASA Technical Reports Server (NTRS)

    Sobol, Paul J.; Faucher, Joseph E.

    1993-01-01

    Explosive forming, wax filling, and any one of welding, diffusion bonding, or brazing used in method of manufacturing large, complicated shell-and-liner vessels or structures. Method conceived for manufacture of film-cooled rocket nozzles but applicable to joining large coaxial shells and liners in general.

  6. STELLAR POPULATIONS IN THE OUTER HALO OF THE MASSIVE ELLIPTICAL M49

    SciTech Connect

    Mihos, J. Christopher; Harding, Paul; Rudick, Craig S.; Feldmeier, John J. E-mail: paul.harding@case.edu E-mail: jjfeldmeier@ysu.edu

    2013-02-20

    We use deep surface photometry of the giant elliptical M49 (NGC 4472), obtained as part of our survey for diffuse light in the Virgo Cluster, to study the stellar populations in its outer halo. Our data trace M49's stellar halo out to {approx}100 kpc (7r{sub e}), where we find that the shallow color gradient seen in the inner regions becomes dramatically steeper. The outer regions of the galaxy are quite blue (B - V {approx} 0.7); if this is purely a metallicity effect, it argues for extremely metal-poor stellar populations with [Fe/H] < -1. We also find that the extended accretion shells around M49 are distinctly redder than the galaxy's surrounding halo, suggesting that we are likely witnessing the buildup of both the stellar mass and metallicity in M49's outer halo due to late time accretion. While such growth of galaxy halos is predicted by models of hierarchical accretion, this growth is thought to be driven by more massive accretion events which have correspondingly higher mean metallicity than inferred for M49's halo. Thus the extremely metal-poor nature of M49's extended halo provides some tension against current models for elliptical galaxy formation.

  7. Development of a Prototype Nickel Optic for the Constellation-X Hard-X-Ray Telescope

    NASA Technical Reports Server (NTRS)

    Basso, S.; Bruni, R. J.; Citerio, O.; Engelhaupt, D.; Ghigo, M.; Gorenstien, P.; Mazzoleni, F.; ODell, S. L.; Pareschi, G.; Ramsey, B. D.

    2003-01-01

    The Constellation-X mission, planned for launch in 2011, will feature an array of hard-x ray telescopes with a total collecting area goal of 1500 square centimeters at 40 keV. Various technologies are currently being investigated for the optics of these telescopes including multilayer-coated Eletroformed-Nickel-Replicated (ENR) shells. The attraction of the ENR process is that the resulting full-shell optics are inherently stable and offer the promise of good angular resolution and enhanced instrument sensitivity. The challenge for this process is to meet a relatively tight weight budget with a relatively dense material (rho nickel = 9 grams per cubic centimeters.) To demonstrate the viability of the ENR process we are fabricating a prototype HXT mirror module to be tested against a competing segmented-glass-shell optic. The ENR prototype will consist of 5 shells of diameters from 150 mm to 280 mm and of 426 mm total length. To meet the stringent weight budget for Con-X, the shells will be only 150 micron thick. The innermost of these will be coated with Iridium, while the remainder will be coated with graded-density multilayers. Mandrels for these shells are currently under fabrication (Jan 03), with the first shells scheduled for production in February 03. A tentative date of late Summer has been set for prototype testing. Issues currently being addressed are the control of stresses in the multiplayer coating and ways of mitigating their effects on the figure of the necessarily thin shells. Also, the fabrication, handling and mounting of these shells without inducing permanent figure distortions. A full status report on the prototype optic will be presented along with test results as available.

  8. The jump-off velocity of an impulsively loaded spherical shell

    SciTech Connect

    Chabaud, Brandon M.; Brock, Jerry S.

    2012-04-13

    We consider a constant temperature spherical shell of isotropic, homogeneous, linearly elastic material with density {rho} and Lame coefficients {lambda} and {mu}. The inner and outer radii of the shell are r{sub i} and r{sub o}, respectively. We assume that the inside of the shell is a void. On the outside of the shell, we apply a uniform, time-varying pressure p(t). We also assume that the shell is initially at rest. We want to compute the jump-off time and velocity of the pressure wave, which are the first time after t = 0 at which the pressure wave from the outer surface reaches the inner surface. This analysis computes the jump-off velocity and time for both compressible and incompressible materials. This differs substantially from [3], where only incompressible materials are considered. We will consider the behavior of an impulsively loaded, exponentially decaying pressure wave p(t) = P{sub 0{sup e}}{sup -{alpha}t}, where {alpha} {ge} 0. We notice that a constant pressure wave P(t) = P{sub 0} is a special case ({alpha} = 0) of a decaying pressure wave. Both of these boundary conditions are considered in [3].

  9. Metrics for Hard Goods Merchandising.

    ERIC Educational Resources Information Center

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

    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…

  10. FATIGUE OF BIOMATERIALS: HARD TISSUES

    PubMed Central

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

    2009-01-01

    The fatigue and fracture behavior of hard tissues are topics of considerable interest today. This special group of organic materials comprises the highly mineralized and load-bearing tissues of the human body, and includes bone, cementum, dentin and enamel. An understanding of their fatigue behavior and the influence of loading conditions and physiological factors (e.g. aging and disease) on the mechanisms of degradation are essential for achieving lifelong health. But there is much more to this topic than the immediate medical issues. There are many challenges to characterizing the fatigue behavior of hard tissues, much of which is attributed to size constraints and the complexity of their microstructure. The relative importance of the constituents on the type and distribution of defects, rate of coalescence, and their contributions to the initiation and growth of cracks, are formidable topics that have not reached maturity. Hard tissues also provide a medium for learning and a source of inspiration in the design of new microstructures for engineering materials. This article briefly reviews fatigue of hard tissues with shared emphasis on current understanding, the challenges and the unanswered questions. PMID:20563239

  11. Playing the Numbers: Hard Choices

    ERIC Educational Resources Information Center

    Doyle, William R.

    2009-01-01

    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

  12. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Outer continental shelf pipelines. 192.10 Section... shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf (as defined in the Outer Continental Shelf Lands Act; 43 U.S.C. 1331) must identify on all their respective pipelines...

  13. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Outer continental shelf pipelines. 192.10 Section... shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf (as defined in the Outer Continental Shelf Lands Act; 43 U.S.C. 1331) must identify on all their respective pipelines...

  14. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Outer continental shelf pipelines. 192.10 Section... shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf (as defined in the Outer Continental Shelf Lands Act; 43 U.S.C. 1331) must identify on all their respective pipelines...

  15. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Outer continental shelf pipelines. 195.9 Section... HAZARDOUS LIQUIDS BY PIPELINE General 195.9 Outer continental shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf must identify on all their respective pipelines the specific...

  16. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Outer continental shelf pipelines. 192.10 Section... shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf (as defined in the Outer Continental Shelf Lands Act; 43 U.S.C. 1331) must identify on all their respective pipelines...

  17. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Outer continental shelf pipelines. 195.9 Section... HAZARDOUS LIQUIDS BY PIPELINE General 195.9 Outer continental shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf must identify on all their respective pipelines the specific...

  18. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Outer continental shelf pipelines. 195.9 Section... HAZARDOUS LIQUIDS BY PIPELINE General 195.9 Outer continental shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf must identify on all their respective pipelines the specific...

  19. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Outer continental shelf pipelines. 195.9 Section... HAZARDOUS LIQUIDS BY PIPELINE General 195.9 Outer continental shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf must identify on all their respective pipelines the specific...

  20. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Outer continental shelf pipelines. 192.10 Section... shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf (as defined in the Outer Continental Shelf Lands Act; 43 U.S.C. 1331) must identify on all their respective pipelines...

  1. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Outer continental shelf pipelines. 195.9 Section... HAZARDOUS LIQUIDS BY PIPELINE General 195.9 Outer continental shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf must identify on all their respective pipelines the specific...

  2. 33 CFR 117.323 - Outer Clam Bay

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Outer Clam Bay 117.323 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Florida 117.323 Outer Clam Bay The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on signal if at least 30 minutes advance notice is given....

  3. 33 CFR 117.323 - Outer Clam Bay

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Outer Clam Bay 117.323 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Florida 117.323 Outer Clam Bay The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on signal if at least 30 minutes advance notice is given....

  4. 33 CFR 117.323 - Outer Clam Bay.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Outer Clam Bay. 117.323 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Florida 117.323 Outer Clam Bay. The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on signal if at least 30 minutes advance notice is given....

  5. 33 CFR 117.323 - Outer Clam Bay

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Outer Clam Bay 117.323 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Florida 117.323 Outer Clam Bay The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on signal if at least 30 minutes advance notice is given....

  6. 33 CFR 117.323 - Outer Clam Bay.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Outer Clam Bay. 117.323 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Florida 117.323 Outer Clam Bay. The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on signal if at least 30 minutes advance notice is given....

  7. Composite shell spacecraft seat

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    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.

  8. Lunar and Planetary Science XXXV: Outer Solar System

    NASA Technical Reports Server (NTRS)

    2004-01-01

    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.

  9. Surface ices in the outer solar system

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.; Cruikshank, Dale P.

    1994-01-01

    Planetary volatile inventories are products of several factors: (1) condensation-accretion of pre-planetary material which determines the bulk volatile inventory; (2) energy history of a planet, including timing, causes, and mechanisms of degassing; (3) the volatile sinks, including temporary, long term, and permanent; and (4) external processes operating on the volatile inventory. Information regarding the current surface compositions provide insight into both internal and surface-atmosphere evolutionary history. Our discussion focuses upon the surface composition of outer solar system planets and satellites as determined by spacecraft and telescopic spectral observations. We provide a review and an update of the recent work by Cruikshank and Brown that includes more recent observations and interpretations. In the context of formation and evolution of solar system bodies, the interesting ices typically considered are simple molecules formed from elements having high cosmic abundances. These mainly include ices of H2O, NH3, SO2, H2S, CH4, CO, CO2, and N2. In the solid state, these ices have vibrational spectral features, analogous to their gaseous counterparts but rotational transitions are quenched, that lie in the near- and mid-infrared. The overtone and combination modes, occurring in the visible and near-IR region, are of particular importance as standard observational techniques used to identify these ices rely upon reflected solar energy. Table I summarizes the ices found on various bodies in the outer solar system. H2O is most abundant surface material in the inner and middle regions while more volatile species appear to dominate surfaces in the outermost edge of the outer solar system.

  10. The Young Outer Disk of M83

    NASA Astrophysics Data System (ADS)

    Davidge, T. J.

    2010-08-01

    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).

  11. The outer haloes of massive, elliptical galaxies

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    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 σψ > σr > σθ.

  12. Lineage tracing of the bivalve shell field with special interest in the descendants of the 2d blastomere.

    PubMed

    Mohri, Masakuni; Hashimoto, Naoki; Wada, Hiroshi

    2016-03-01

    By evolving bilaterally separated shell plates, bivalves acquired a unique body plan in which their soft tissues are completely protected by hard shell plates. In this unique body plan, mobility between the separated shell plates is provided by novel structures such as a ligament and adductor muscles. As a first step towards understanding how the bivalve body plan was established, we investigated the development of the separated shell plates and ligament. Over 100 years ago, it was hypothesized that the development of separated shell plates is tightly linked with the unique cell cleavage (division) pattern of bivalves during development, wherein each bilateral daughter cell of the 2d descendant 2d(1121) develops into one of the bilateral shell fields. In this study, we tested this hypothesis by tracing the cell lineages of the Japanese purple mussel Septifer virgatus. Although the shell fields were found to be exclusively derived from the bilateral descendant cells of 2d: 2d(11211) and 2d(11212), the descendants of these cells were not restricted to shell fields alone, nor were they confined to the left or right side of the shell field based on their lineage. Our study demonstrated that ligament cells are also derived from 2d(11211) and 2d(11212), indicating that the ligament cells emerged as a subpopulation of shell field cells. This also suggests that the establishment of the novel developmental system for the ligament cells was critical for the evolution of the unique body plan of bivalves. PMID:26932681

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

    SciTech Connect

    Kubo, U.; Tsubakihara, H.

    1987-07-01

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

  14. Spectral sensitization with dyes of core-silver halide shell microsystems

    NASA Astrophysics Data System (ADS)

    Tyurin, A. V.; Zhukov, S. A.; Churashov, V. P.

    2015-09-01

    We have studied spectral sensitization with anionic dyes of core-silver halide shell microsystems cores of which can be either nonsilver or silver halide compounds. Conditions under which dye sensitizers, being adsorbed on cores, remain under silver halide shells after their growing are considered. Comparison of results of sensitometric and low-temperature ( T = 77 K) luminescent measurements have shown that these conditions are determined by the charge state of cations of microsystem cores. If the shell contains the same univalent component in its composition as the core does, as in the case in which the core is a silver halide compound, the anionic dye is displaced to the outer surface of the shell. If the core contains a divalent cationic component, as in the case in which the core is a nonsilver compound, the dye remains under the silver halide shell; i.e., it is overgrown by the shell. We have shown that the charge state of core cations affects the character of the core interaction with anionic dyes, which ensures differences in the spectral sensitization of core-silver halide shell microsystems, as well as differences in the dye photoexcitation relaxation in them.

  15. Two-shell vortex and antivortex dynamics in a Corbino superconducting disk

    NASA Astrophysics Data System (ADS)

    Cabral, L. R. E.; de Aquino, Belisa R. C. H. T.; Silva, Clcio C. de Souza; Miloevi?, Milorad V.; Peeters, Franois M.

    2016-01-01

    We examine theoretically the dynamics of two vortex shells in pinning-free superconducting thin disks in the Corbino geometry. In the first considered case, the inner shell is composed of vortices and the outer one of antivortices, corresponding to a state induced by the stray field of an off-plane magnetic dipole placed on top of the superconductor. In the second considered case, both shells comprise vortices induced by a homogeneous external field. We derive the equation of motion for each shell within the Bardeen-Stephen model and study the dynamics analytically by assuming both shells are rigid and commensurate. In both cases, two distinct regimes for vortex shell motion are identified: For low applied currents the entire configuration rotates rigidly, while above a threshold current the shells decouple from each other and rotate at different angular velocities. Analytical expressions for the decoupling current, the recombination time in the decoupled phases, as well as the voltage-current characteristics are presented. Our analytical results are in excellent agreement with numerical molecular dynamics simulations of the full many-vortex problem.

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

    PubMed

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

    2012-10-01

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

  17. Overview of 2008 Outer Planet Flagship Studies

    NASA Technical Reports Server (NTRS)

    Reh, Kim R.

    2008-01-01

    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.

  18. Dark matter in the outer solar system

    NASA Technical Reports Server (NTRS)

    Owen, T.; Cruikshank, D.; De Bergh, C.; Geballe, T.

    1994-01-01

    There are now a large number of small bodies in the outer solar system that are known to be covered with dark material. Attempts to identify that material have been thwarted by the absence of discrete absorption features in the reflection spectra of these planetesimals. An absorption at 2.2 micrometers that appeared to be present in several objects has not been confirmed by new observations. Three absorptions in the spectrum of the unusually red planetesimal 5145 Pholus are well-established, but their identity remains a mystery.

  19. Meridional plasma flow in the outer heliosphere

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    Voyager 2 observations made in the outer heliosphere near 25 AU and within 2 deg of the heliographic equatorial plane show periodic variations in the meridional (North/South) flow velocities that are much more prominent than the East/West variations. An autocorrelation analysis shows that the flow variation has a period of about 25.5 days in the latter half of 1986, in approximate agreement with the solar rotation period. The results suggest that increased pressure in interaction regions remains the best candidate for the driver of the nonradial flows.

  20. Dishwasher For Earth Or Outer Space

    NASA Technical Reports Server (NTRS)

    Tromble, Jon D.

    1991-01-01

    Dishwashing machine cleans eating utensils in either Earth gravity or zero gravity of outer space. Cycle consists of three phases: filling, washing, and draining. Rotation of tub creates artificial gravity aiding recirculation of water during washing phase in absence of true gravity. Centrifugal air/water separator helps system function in zero gravity. Self-cleaning filter contains interdigitating blades catching solid debris when water flows between them. Later, blades moved back and forth in scissor-like manner to dislodge debris, removed by backflow of water.

  1. Eccentric features in Saturn's outer C ring

    SciTech Connect

    Porco, C.C.; Nicholson, P.D.

    1987-11-01

    The present search for possible eccentric and inclined features in the outer C ring of Saturn measured all sharp-edged feature radii in Voyager C ring data. The Maxwell ringlet and two other narrow ringlets, 1.470R(s) and 1.495R(s) are found to be eccentric; the latter is best fitted by a model describing a freely precessing Keplerian ellipse, while the former is not conclusively fitted by either a resonant forcing or a free precession model. These two eccentric ringlets are compared with the Titan and Maxwell ringlets. 51 references.

  2. Outer atmospheres of giant and supergiant stars

    NASA Technical Reports Server (NTRS)

    Brown, A.

    1984-01-01

    The properties of the chromospheres, transition regions and coronas of cool evolved stars are reviewed based primarily on recent ultraviolet and X-ray studies. Determinations of mass loss rates using new observational techniques in the ultraviolet and radio spectral regions are discussed and observations indicating general atmospheric motions are considered. The techniques available for the quantitative modeling of these atmospheres are outlined and recent results discussed. Finally, the current rudimentary understanding of the evolution of these outer atmospheres and its causes are considered.

  3. Outer planet spacecraft temperature testing and analysis

    NASA Technical Reports Server (NTRS)

    Hoffman, A. R.; Avila, A.

    2002-01-01

    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.

  4. Core-shell nanospheres for oligonucleotide delivery. V: adsorption/release behavior of 'stealth' nanospheres.

    PubMed

    Tondelli, Luisa; Ballestri, Marco; Magnani, Laura; Vivarelli, Daniela; Fini, Adamo; Cerasi, Aurora; Chiarantini, Laura; Sparnacci, Katia; Laus, Michele

    2003-01-01

    The adsorption/release behavior of oligodeoxynucleotides (ODNs) on new PEGylated core-shell polymethylmethacrylate nanospheres is described. The outer shell consists of alkyl chains containing quaternary ammonium groups and of poly(ethylene glycol) chains, both covalently bound to the inner core. Ion pair formation between negatively charged ODN phosphate groups and positively charged groups on the nanosphere surface is the main interaction mechanism. No cellular toxicity in HL60 cells is observed at nanosphere concentrations required for biologically active ODN delivery. These results indicate that these novel cationic polymeric nanoparticles are safe and represent promising vectors for oligonucleotide delivery. PMID:14768909

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

    NASA Astrophysics Data System (ADS)

    Balazy, Piotr; Kuklinski, Piotr

    2013-03-01

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

  6. Fabrication of Spherical Reflectors in Outer Space

    NASA Technical Reports Server (NTRS)

    Wang, Yu; Dooley, Jennifer; Dragovan, Mark; Serivens, Wally

    2005-01-01

    A process is proposed for fabrication of lightweight spherical reflectors in outer space for telescopes, radio antennas, and light collectors that would be operated there. The process would obviate the relatively massive substrates and frames needed to support such reflectors in normal Earth gravitation. According to the proposal, fabrication of a reflector would begin with blowing of a bubble to the specified reflector radius. Taking advantage of the outer-space vacuum as a suitable environment for evaporative deposition of metal, a metal-evaporation source would be turned on and moved around the bubble to deposit a reflective metal film over the specified reflector area to a thickness of several microns. Then the source would be moved and aimed to deposit more metal around the edge of the reflector area, increasing the thickness there to approximately equal to 100 micron to form a frame. Then the bubble would be deflated and peeled off the metal, leaving a thin-film spherical mirror having an integral frame. The mirror would then be mounted for use. The feasibility of this technology has been proved by fabricating a prototype at JPL. As shown in the figure, a 2-in. (.5-cm) diameter hemispherical prototype reflector was made from a polymer bubble coated with silver, forming a very smooth surface.

  7. Radio Emissions from the Outer Heliosphere

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Kurth, W. S.

    1996-01-01

    For nearly fifteen years the Voyager 1 and 2 spacecraft have been detecting an unusual radio emission in the outer heliosphere in the frequency range from about 2 to 3 kHz. Two major events have been observed, the first in 1983-84 and the second in 1992-93. In both cases the onset of the radio emission occurred about 400 days after a period of intense solar activity, the first in mid-July 1982, and the second in May-June 1991. These two periods of solar activity produced the two deepest cosmic ray Forbush decreases ever observed. Forbush decreases are indicative of a system of strong shocks and associated disturbances propagating outward through the heliosphere. The radio emission is believed to have been produced when this system of shocks and disturbances interacted with one of the outer boundaries of the heliosphere, most likely in the vicinity of the the heliopause. The emission is believed to be generated by the shock-driven Langmuir-wave mode conversion mechanism, which produces radiation at the plasma frequency (f(sub p)) and at twice the plasma frequency (2f(sub p)). From the 400-day travel time and the known speed of the shocks, the distance to the interaction region can be computed, and is estimated to be in the range from about 110 to 160 AU.

  8. Future exploration of the outer solar system

    NASA Astrophysics Data System (ADS)

    Johnson, T.

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

  9. OSSOS: The Outer Solar System Origins Survey

    NASA Astrophysics Data System (ADS)

    Gladman, Brett; Bannister, Michele; Kavelaars, Jj; Petit, Jean-Marc; Gwyn, Stephen; Chen, Ying-Tung

    2014-11-01

    We present the first detection set from the Outer Solar System Origins Survey (OSSOS) which is a mammoth 560-hour CFHT Large Program over 4 years (finishing January 2017). This is likely to be the largest Kuiper Belt survey before LSST comes on line (in terms of the number of precise transneptunian object (TNO) orbits it provides).OSSOS studies gradually-slewing 21-square degree blocks of sky that are repeatedly imaged in many dark runs over two semesters. This strategy is designed to detect and track TNOs in order to provide extremely high-quality orbits in a short amount of time; in 16-18 month arcs we are obtaining fractional semimajor axis uncertainties in the range 0.01-0.1% and accuracies in the libration amplitudes of resonant objects better than 10 degrees, due to mean astrometric residuals routinely being of order 50-100 milliarcseconds.This talk will present the survey design and full detection sample for objects observed in the first half of 2013 and 2014. We will report how adding these detections to those from the Canada-France Ecliptic Plane Survey (CFEPS) modifies conclusions about the orbital and size distribution of main classical Kuiper Belt, as well as other non-resonant sub-populations. In particular, because OSSOS is sensitive to, and has detected objects, from 8 AU to beyond 60 AU, we will report on how the combined distance and magnitude distribution impact dicsussions of the absolute magnitude distribution of outer Solar System objects.

  10. Residual Stress Testing of Outer 3013 Containers

    SciTech Connect

    Dunn, K.

    2004-02-12

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

  11. The Utility of Outer Planet Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hill, Steven M.

    2015-05-01

    Amateur astronomers can now routinely record disk integrated spectra of the outer planets at moderate to high spectral and temporal resolution. Initial studies of the application of small telescope spectroscopy to the outer planets (including Titan) were published in the early 2000's. This paper seeks to revisit these capabilities in conjunction with advances in understanding the target atmospheres, available low-cost instrumentation, and current observational needs within the research community. First, observations and data reduction are presented. Second, the basic capability of small-scope planetary spectroscopy is re-validated and spectra of Jupiter, Saturn, Titan, Uranus and Neptune are compared to professional spectra at similar resolutions. Third, effective line-of-sight methane number density, etaN(CH4), is retrieved using best fits to integrated band strengths for both classical single reflecting layer models and classical homogeneous scattering models. The observations and methane number densities obtained lie within the scatter seen in published literature. Fourth, the challenges to making highly repeatable, well calibrated observations are examined. This is done in the context of monitoring for transient changes in band strengths, e.g., as result of longitudinal variations clouds, hazes and/or surface albedo. Jupiter provides an easy, high signal-to-noise test case where the detectability of Great Red Spot transits is evaluated. In conclusion, we summarize the results, make recommendations for extending this work and suggest a campaign that could be carried out immediately by appropriately equipped amateurs.

  12. Magnetically self-assembled SrFe12O19/Fe-Co core/shell particles

    SciTech Connect

    Xu, X; Park, J; Hong, YK; Lane, AM

    2015-02-15

    Epitaxial growth to synthesize core/shell-structured materials is limited because large lattice mismatches are common between materials. Magnetically hard/soft, core/shell-structured materials can be potentially used for rare-earth free permanent magnets, but their synthesis presents a challenge. We report a wet chemistry method to synthesize core/shell structured particles consisting of a magnetically hard SrFe12O19 core and a soft Fe-Co shell, with a lattice mismatch of similar to 100%, which cannot be achieved by conventional epitaxial growth or other alternative methods. When decreasing the size of the magnetically soft Fe-Co nanoclusters to below 5 nm, we show that they can be magnetically attracted by the hard SrFe12O19 to form core/shell structured particles. An AC demagnetization experiment demonstrates the formation mechanism of the core/shell particles, and their magnetic hysteresis loop shows potential for use as rare-earth free permanent magnets. Published by Elsevier B.V.

  13. Hard spheres out of equilibrium

    NASA Astrophysics Data System (ADS)

    Hermes, M.

    2010-05-01

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

  14. Baroplastic core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2004-03-01

    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.

  15. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

  16. Study of circumferential waves and their interaction with defects on cylindrical shells using line-source laser ultrasonics

    NASA Astrophysics Data System (ADS)

    Gao, Weimin; Glorieux, Christ; Thoen, Jan

    2002-05-01

    An application of laser ultrasonics to investigate circumferential waves and their interaction with defects on cylindrical structures is presented. Due to the high effectiveness of the laser line-source generation regime and the broadband nature of the system, circumferential waves could be generated and detected with a wide bandwidth and an excellent signal-to-noise ratio. A clear recognition of multimode wave forms is achieved by two-dimensional Fourier transform signal processing. Measurements were also made on a cylindrical shell with a crack-like defect which was simulated by an artificial groove on the surface of the specimen. The interaction of the circumferential waves with a defect in the inner or outer surface of the thin cylindrical shell has been studied. The results may lead to an application for defect identification at the inner or outer surface of thin cylindrical shells.

  17. Oceans, Ice Shells, and Life on Europa

    NASA Technical Reports Server (NTRS)

    Schenk, Paul

    2002-01-01

    The four large satellites of Jupiter are famous for their planet-like diversity and complexity, but none more so than ice-covered Europa. Since the provocative Voyager images of Europa in 1979, evidence has been mounting that a vast liquid water ocean may lurk beneath the moon's icy surface. Europa has since been the target of increasing and sometimes reckless speculation regarding the possibility that giant squid and other creatures may be swimming its purported cold, dark ocean. No wonder Europa tops everyone's list for future exploration in the outer solar system (after the very first reconnaissance of Pluto and the Kuiper belt, of course). Europa may be the smallest of the Galilean moons (so-called because they were discovered by Galileo Galilei in the early 17th century) but more than makes up for its diminutive size with a crazed, alien landscape. The surface is covered with ridges hundreds of meters high, domes tens of kilometers across, and large areas of broken and disrupted crust called chaos. Some of the geologic features seen on Europa resemble ice rafts floating in polar seas here on Earth-reinforcing the idea that an ice shell is floating over an ocean on this Moon-size satellite. However, such features do not prove that an ocean exists or ever did. Warm ice is unusually soft and will flow under its own weight. If the ice shell is thick enough, the warm bottom of the shell will flow, as do terrestrial glaciers. This could produce all the observed surface features on Europa through a variety of processes, the most important of which is convection. (Convection is the vertical overturn of a layer due to heating or density differences-think of porridge or sauce boiling on the stove.) Rising blobs from the base of the crust would then create the oval domes dotting Europa's surface. The strongest evidence for a hidden ocean beneath Europa's surface comes from the Galileo spacecraft's onboard magnetometer, which detected fluctuations in Jupiter's magnetic field consistent with a conductor inside Europa. The most likely conductor: a somewhat salty ocean.

  18. Crack problems in cylindrical and spherical shells

    NASA Technical Reports Server (NTRS)

    Erdogan, F.

    1976-01-01

    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.

  19. MicroShell Minimalist Shell for Xilinx Microprocessors

    NASA Technical Reports Server (NTRS)

    Werne, Thomas A.

    2011-01-01

    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.

  20. Hardness Alternation in ?,?-Alkanedicarboxylic Acids.

    PubMed

    Mishra, Manish Kumar; Ramamurty, Upadrasta; Desiraju, Gautam R

    2015-10-01

    The variation of hardness as a function of the number of carbon atoms in ?,?-alkanedicarboxylic acids, C(N)H(2N-2)O4 (4?N?9), was examined by recourse to nanoindentation on the major faces of single crystals. Hardness exhibits odd-even alternation, with the odd acids being softer and the even ones harder; the differences decrease with increasing chain length. These variations are similar to those seen for other mechanical, physical, and thermal properties of these diacids. The softness of odd acids is rationalized due to strained molecular conformations in them, which facilitate easier plastic deformation. Relationships between structural features, such as interplanar spacing, interlayer separation distance, molecular chain length, and signatures of the nanoindentation responses, namely, discrete displacement bursts, were also examined. Shear sliding of molecular layers past each other during indentation is key to the mechanism for plastic deformation in these organic crystals. PMID:25919633

  1. Ultrasonic material hardness depth measurement

    DOEpatents

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

    1997-01-01

    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.

  2. Ultrasonic material hardness depth measurement

    DOEpatents

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

    1997-07-08

    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.

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

    PubMed Central

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

    1987-01-01

    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 PMID:3025168

  4. Results on hard diffractive production

    SciTech Connect

    Goulianos, K.

    1995-07-01

    The results of experiments at hadron colliders probing the structure of the pomeron through hard diffraction are reviewed. Some results on deep inelastic diffractive scattering obtained a HERA are also discussed and placed in perspective. By using a properly normalized pomeron flux factor in single diffraction dissociation, as dictated by unitarity, the pomeron emerges as a combination of valence quark and gluon color singlets in a ratio suggested by asymptopia.

  5. Schwannoma of the hard palate

    PubMed Central

    Sahoo, Pradyumna Kumar; Mandal, Palash Kumar; Ghosh, Saradindu

    2014-01-01

    Schwannomas are benign encapsulated perineural tumors. The head and neck region is the most common site. Intraoral origin is seen in only 1% of cases, tongue being the most common site; its location in the palate is rare. We report a case of hard-palate schwannoma with bony erosion which was immunohistochemically confirmed. The tumor was excised completely intraorally. After two months of follow-up, the defect was found to be completely covered with palatal mucosa. PMID:25298716

  6. Microwave assisted hard rock cutting

    DOEpatents

    Lindroth, David P.; Morrell, Roger J.; Blair, James R.

    1991-01-01

    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).

  7. Comparative study of shell swab and shell crush methods for the recovery of Salmonella from shell eggs.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Swabbing (SW) is the standard methodology for the recovery of resident microorganisms from shell eggs in Japan. A comparative study of shell swab (SW) and a shell crush (CR) technique was performed to recover the laboratory-inoculated Salmonella from shell eggs. It was found that the recovery of ...

  8. AM03-AM121-115 Hard X-Ray Optics Development at MSFC

    NASA Technical Reports Server (NTRS)

    Ramsey, Brian; Elsner, Ron; Engelhaupt, Darell; Gubarev, Mikhail; Kolodziejczak, Jeffery; Martin, Greg; ODell, Steve; Speegle, Chet; Weiskopf, Martin

    2003-01-01

    We have developed the electroformed-nickel replication process to enable us to fabricate light-weight hard-x-ray region. Two projects currently utilizing this technology are the production of over 250 r from 5 to 10 cm, for our HERO balloon payload, and 15- and 23-cm-diameter shells for a prototype module. The challenge for the former is to fabricate, mount, align and fly a large number of high-r constraints of a modest budget. For the latter, the challenge is to maintain high angular resolution shell thicknesses (100 micron) which make the shells extremely sensitive to electroforming stresses process does not degrade the ultra-smooth surface finish (approx. 3 A required for eventual multilayer c on these two programs.

  9. H I shells, supershells, shell-like objects, and 'worms'

    NASA Astrophysics Data System (ADS)

    Heiles, C.

    1984-08-01

    The present photographic representations of the combinations of two H I surveys and high contrast photographs for particular velocities (made in order to exhibit weak H I features) have been used to prepare a list of H I shells, supershells, and shell-like objects. Attention is given to the structure of three shell-like objects associated with high velocity gas, as well as with gas at all velocities that is associated with radio continuum loops I, II, and III. The gas filaments or 'worms' found by spatial filtering to be crawling away from the galactic plane in the inner Galaxy are probably parts of shells that are open at the top. An assessment of observational data on shells and supershells indicates no unique relationship between shells and any other type of astronomical object. Stellar winds and supernovas in stellar associations are inadequate energy supplies for the largest observed supershells, unless star formation activity is unusually great. An alternative energy source, high velocity cloud collisions with the galactic disk, is consistent with several aspects of the data.

  10. THE OUTER DISKS OF DWARF IRREGULAR GALAXIES

    SciTech Connect

    Hunter, Deidre A.; Massey, Philip; Wilsey, Nick; Riabokin, Malanka; Elmegreen, Bruce G.; Oh, Se-Heon; Anderson, Ed; Nordgren, Tyler E. E-mail: phil.massey@lowell.edu E-mail: riabokin@msu.edu E-mail: seheon-oh@ast.uct.ac.za E-mail: tyler_nordgren@redlands.edu

    2011-10-15

    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.

  11. Radio seismology of the outer solar corona

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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 Alfvn 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 Frderung der wissenschaftlichen Forschung' under project P24740-N27.

  12. Insulative laser shell coupler

    SciTech Connect

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

    1994-09-20

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

  13. Insulative laser shell coupler

    DOEpatents

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

    1994-01-01

    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.

  14. Analysis of toughening mechanisms in the Strombus gigas shell.

    PubMed

    DiPette, Scott; Ural, Ani; Santhanam, Sridhar

    2015-08-01

    A finite element analysis of the fracture mechanisms in the Strombus gigas conch shell is presented in this work. The S. gigas shell has a complex microarchitecture that consists of three main macroscopic layers of calcium carbonate: the inner, middle, and outer layers. Each layer is composed of lamellae of calcium carbonate, held together by a cohesive organic protein. As a result of this elaborate architecture, the S. gigas shell exhibits a much greater damage tolerance than the calcium carbonate by itself, with a work of fracture reported to be three magnitudes of order greater. The two main energy dissipating factors that contribute to this are multiple, parallel cracking along first-order interfaces in the inner and outer layers and crack bridging through the second-order interfaces of the middle layer. Finite element analysis was conducted to simulate and replicate flexural strength and work-of-fracture results obtained in the literature for both dry and wet physical bend test specimens. Several parameters were varied including protein strength and fracture toughness, initial protein damage, and the relative heights of macroscopic layers in order to create a model that predicted published, experimental results. The simulations indicate that having some initially weakened protein interfaces is key to matching the parallel cracking in the inner layer of the physical specimens. The wet models exhibit significantly higher work of fracture compared to the dry specimens in large part due to a crack growth resistance behavior in the middle layer, which was successfully modeled. The parametric studies that have been performed on the finite element models provide guidelines for manufacturing the ideal S. gigas-inspired, biomimetic composite. PMID:25955562

  15. Micro/nanomechanical characterization of a natural nanocomposite materialthe shell of Pectinidae

    NASA Astrophysics Data System (ADS)

    Li, Xiaodong; Nardi, Patrick

    2004-01-01

    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 microscope. It was found from nanoindentation tests that the shell exhibits a hardness of about 5 GPa and elastic modulus of about 87 GPa. Nanoindentation resulted in pile-up around the indent. In the middle and bottom layers primary cracks propagate along the first-order lamellar boundaries and numerous secondary cracks branch off along the second-order lamellar boundaries. The additional energy required for crack propagation results from the secondary cracks along the second-order lamellar boundaries. Cracks formed in the top layer of the shell do not show the crack diversion mechanism due to the lack of first-order lamellar organization. Fracture mechanisms were discussed in conjunction with architecture, hardness, elastic modulus, and energy-dissipation during cracking.

  16. Why Are Drugs So Hard to Quit?

    MedlinePLUS Videos and Cool Tools

    ... Quitting drugs is hard because addiction is a brain disease. Your brain is like a control tower that sends out ... and choices. Addiction changes the signals in your brain and makes it hard to feel OK without ...

  17. Impact of aging on radiation hardness

    SciTech Connect

    Shaneyfelt, M.R.; Winokur, P.S.; Fleetwood, D.M.

    1997-07-01

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

  18. Collapsing thin shells with rotation

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  19. Organic Matter in the Outer Solar System

    NASA Technical Reports Server (NTRS)

    Cruiskshank, Dale P.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Many solid bodies in the outer Solar System are covered with ices of various compositions, including water, carbon dioxide, methane, nitrogen, and other molecules that are solid at the low temperatures that prevail there. These ices have all been detected by remote sensing observations made with telescopes on Earth, or more recently, spacecraft in orbit (notably Galileo at Jupiter). The data also reveal other solid materials that could be minerals or complex carbon-bearing organic molecules. A study in progress using large ground-based telescopes to acquire infrared spectroscopic data, and laboratory results on the optical properties of complex organic matter, seeks to identify the non-icy materials on several satellites of Saturn, Uranus, and Neptune. The work on the satellites of Saturn is in part preparatory to the Cassini spacecraft investigation of the Saturn system, which will begin in 2004 and extend for four years.

  20. Near infrared imaging of the outer planets

    NASA Technical Reports Server (NTRS)

    Matthews, K.; Soifer, B. T.

    1991-01-01

    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.

  1. Formation of the outer planets and satellites

    NASA Technical Reports Server (NTRS)

    Cameron, A. G. W.

    1977-01-01

    A mechanism for the formation of the outer planets is proposed, the basis of which is the idea that the giant planets contain an excess of chemically condensable materials over solar composition. Planetary cores were formed by the clumping together of chemically condensed bodies forming a thin disk in the solar nebula. Gas surrounding a core becomes unstable against collapse onto the core. In the case of Jupiter and Saturn, much of the collapsing gas goes into orbit about the formed planet, forming a relatively thin circumplanetary disks with differential rotation in the prograde sense. For Uranus and Neptune, the dynamical collapse mechanism is unlikely. A disk of gas around Uranus may have been formed during a collision of the protoplanet with a large body. The circumplanetary disks then form the basis for formation of satellite systems, in which the Goldreich-Ward instability mechanism plays a role.

  2. Outer Hair Cell Electromotility in vivo

    NASA Astrophysics Data System (ADS)

    Ramamoorthy, Sripriya; Nuttall, Alfred L.

    2011-11-01

    The effectiveness of outer hair cell (OHC) electro-motility in vivo has been challenged by the expected low-pass filtering of the transmembrane potential due to the cell's own capacitance. The OHC electromotility is characterized here by an electromechanical ratio defined as the ratio of the OHC contraction to the transmembrane potential. This ratio has been measured in isolated cells to be approximately 26 nm/mV. We estimate the OHC electromechanical ratio in vivo from the recently measured displacements of the reticular lamina and the basilar membrane near the 19 kHz characteristic frequency in the basal region of guinea pig cochlea. Our analysis strongly suggests OHC electromotility process is effective for cochlear amplification in vivo at least around the characteristic frequency of the basal location in spite of the low-pass filtering.

  3. The progressive outer retinal necrosis syndrome.

    PubMed

    Holland, G N

    1994-01-01

    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

  4. Phosphoinositide synthesis in bovine rod outer segments

    SciTech Connect

    Gehm, B.D.; McConnell, D.G. )

    1990-06-12

    Phosphoinositide turnover has been implicated in signal transduction in a variety of cells, including photoreceptors. The authors demonstrate here the presence of a complete pathway for rapid synthesis of phosphoinositides in isolated bovine retinal rod outer segments (ROS) free of microsomal contaminants. Synthesis was measured by the incorporation of label from radioactive precursors, ({gamma}-{sup 32}P)ATP and ({sup 3}H)inositol. ({gamma}-{sup 32}P)ATP also produced large amounts of labeled phosphatidic acid. Incorporation of ({sup 3}H)inositol required CTP and Mn{sup 2+}. Mn{sup 2+} and Mg{sup 2+} increased {sup 32}P incorporation into phosphatidylinositol 4-phosphate, while spermine increased phosphoinositide labeling generally. ROS that had been washed to remove soluble and peripheral proteins incorporated less label than unwashed ROS into phosphatidic acid and phosphatidylinositol. No effects of light were detected. Inhibitory effects of high concentrations of nonhydrolyzable GTP analogues were probably due to competition with ATP.

  5. Photometric properties of outer planetary satellites

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    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.

  6. Discovery of Molecular Gas Shells around the Unusual Galaxy Centaurus A

    NASA Astrophysics Data System (ADS)

    2000-03-01

    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 than the stars. As a consequence, one would also expect to observe a certain displacement between the gaseous and stellar shells. The SEST observations ESO PR Photo 08a/00 ESO PR Photo 08a/00 [Preview - JPEG: 343 x 400 pix - 188k] [Normal - JPEG: 686 x 800 pix - 560k] [High-Res - JPEG: 2571 x 3000 pix - 4.4M] Caption : ESO PR Photo 08a/00 shows an optical image of the galaxy Centaurus A (from the 1-m ESO Schmidt telescope at La Silla), with the surrounding shells outlined as contours. The image has been enhanced to show the full extent of the galaxy; due to this process, the central dust band is less visible. The stellar shells (see the text) are indicated in yellow; they are otherwise only visible on very deep images. The contours of the observed distribution of atomic hydrogen gas are white. The radio jet from the active centre of Centaurus A is shown in blue. The new SEST observations prove the existence of carbon monoxide (CO) in the S1 and S2 shells (indicated in red). The field measures approx. 32 x 32 arcmin 2. North is up and East is left. A detailed photo of Centaurus A was recently obtained with the FORS2 instrument at VLT KUEYEN, cf. ESO PR Photo 05b/00 ESO PR Photo 08b/00 ESO PR Photo 08b/00 [Preview - JPEG: 247 x 400 pix - 60k] [Normal - JPEG: 493 x 800 pix - 128k] [High-Res - JPEG: 3000 x 1847 pix - 756k] Caption : ESO PR Photo 08b/00 shows the observed CO emission spectra in the S1 and S2 shells. In both cases, two lines from different molecular states were observed that stand out clearly from the sky noise. The abscissa indicates the velocity (i.e., the radio frequency) and the ordinate the temperature (i.e., the intensity). These diagrammes represent approx. 20 and 30 hours of observation, respectively. In order to test this hypothesis, the astronomers decided to look for the possible presence in the shells around some nearby elliptical galaxies of specific gases that are typical of molecular clouds . The observations were carried out with the 15-metre Swedish-ESO Submillimetre Telescope (SEST) at the ESO La Silla Observatory (Chile). This telescope is the only one of its kind in the southern hemisphere and is particularly suited to register emissions from gases that are common in molecular clouds, e.g. those of carbon monoxide (CO) near a wavelength of 3 mm . This search was successful, notably in the case of Centaurus A , a nearby giant elliptical galaxy with strong radio emission and an active nucleus (AGN), cf. ESO PR Photos 05b-c/00. For the first time, carbon monoxide molecules (CO) were found to be present in two of the surrounding shells, cf. PR Photo 08a/00 . These shells are located at a distance of about 50,000 light-years (15 kpc) from the nucleus of the galaxy and, as can be seen on the photo, the regions of the observed molecules appear to be aligned with the radio jet. This important discovery supports the above mentioned hypothesis and thus provides an important clue as to why there can be gas very far from the centre of an elliptical galaxy after a collision/merger. It is therefore likely that a certain fraction of the gas in the "cannibalized" companion galaxy is made up by small and dense molecular clouds. During the collision, they behave similarly to the stars and end up by forming gaseous shells. The fate of the gas in the shells What is then the likely fate of these gaseous shells? They are most certainly gravitationally well bound to the Centaurus A galaxy and cannot escape into the surrounding intergalactic space. But while the thin and diffuse hydrogen gas will probably move towards the galaxy centre fairly quickly, the more clumpy clouds and the molecular gas therein may remain in the outer shells during long periods. Over time though, also this gas will become less prominent, as the clouds slowly disperse. Interesting perspectives The discovery of carbon monoxide in the shells around Centaurus A opens very interesting avenues for future research on the evolution of galaxies. However, observations like these are very challenging. First of all, as there are comparatively small quantities of gas in most galaxy shells, such measurements require large radio telescopes with high-sensitivity receivers, as well as many hours of observation before sufficiently accurate results (i.e., signal-to-noise ratio) are obtained. In the present case, no less than 20 hours were needed to achieve the secure detection of the emission from CO molecules, as displayed in PR Photo 08b/00 . Moreover, the angular resolution on the sky of the single 15-metre SEST dish is only about 44 arcsec (at the wavelengths of the observed CO lines around 3 mm). This makes it virtually impossible to obtain a clear view of the individual shells in distant galaxies with this telescope. On the other hand, in nearby targets such as Centaurus A, the shells extend over a comparatively large sky area and thus require large-scale mapping, a very time-consuming project. The role of ALMA However, exciting possibilities for more detailed studies, also of much more distant galaxies, are opening with the future Atacama Large Millimeter Array (ALMA) . The collecting area of ALMA is about 7000 m 2 , or over 40 times larger than that of SEST. It will also achieve sub-arcsecond angular resolution when its 64 antennas are combined in the interferometric mode. Together, these properties of ALMA will allow much more sensitive and detailed observations of galaxies at larger distances. When compared to earlier observations of CO near the centre of Centaurus A, the present SEST data show that about 10% of the molecular gas is far outside the centre of this galaxy. As a next step, it would be interesting to examine whether this is also true in other elliptical galaxies with gaseous shells. And will it be possible to detect other molecules in these shells? There will certainly be no lack of opportunities for exciting research in this field, especially with the advent of ALMA , some years from now. More information about this project A research article about this project will appear in the European journal Astronomy & Astrophysics (Vol. 356); it is now available on the web at astro-ph/0003175. Note [1] The team consists of Vassilis Charmandaris (DEMIRM, Observatoire de Paris, France and Cornell University, USA), Françoise Combes (DEMIRM, Observatoire de Paris, France) and Thijs van der Hulst (Kapteyn Institute, University of Groningen, The Netherlands). This work was supported by the European Union via a Marie-Curie fellowship. Contact Dr. Vassilis Charmandaris , Cornell University, Astronomy Department, 106 Space Sciences Bldg., Ithaca, NY 14853, USA. Tel.: +1 (607) 255-8774; e-mail: vassilis@astro.cornell.edu ESO PR Photos may be reproduced, if credit is given to the European Southern Observatory.

  7. FBL Outer Can Welder Acquisition Software

    Energy Science and Technology Software Center (ESTSC)

    2004-01-16

    The Outer Can Welder Data Acquisition Software (OCWDAS) was originally developed by SRTC for use at Hanford to assist in the storage of their excess plutonium in the DOE standard 3013 containers until it can be properly dispositioned using one of the approved DOE methods. After Hanford OCWDAS software was the starting point for the new version developed for FB-Line. New graphical display formats and features were added to this software to make it moremore » robust and operator friendly. Several hardware changes were also made at this time and the software was modified to accommodate these as well. During the welding process, critical weld parameters such as weld current and voltage, can give valuable information about the weld. In the past, weld data from the TIG welding process, such as the bagless transfer system in FB-Line, has been monitored using strip chart recorders. The data from the weld process, recorded on the strip chart recorder traces, are reviewed to analyze the weld. The OCWDAS improves this technology by digitizing the weld data which allows for automation of the analysis process. The OCWDAS performs the necessary functions to perform the data acquisition functions during the 3013 Outer Can Welding Process. It is important to monitor the critical weld parameters, current and voltage, during a weld as they can be used to set acceptance criteria for weld acceptance. The software monitors and records the weld current, voltage, and RPM data. It also records the absolute position of the weld head during the weld process from a quadrature encoder. Digital handshaking between the AMI Welding unit and the OCWDAS ensure that both systems are operational and ready prior to the weld initiation taking place.« less

  8. Outer Planet Mission Studies Neptune Aerocapture

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    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.

  9. FBL Outer Can Welder Acquisition Software

    SciTech Connect

    2004-01-16

    The Outer Can Welder Data Acquisition Software (OCWDAS) was originally developed by SRTC for use at Hanford to assist in the storage of their excess plutonium in the DOE standard 3013 containers until it can be properly dispositioned using one of the approved DOE methods. After Hanford OCWDAS software was the starting point for the new version developed for FB-Line. New graphical display formats and features were added to this software to make it more robust and operator friendly. Several hardware changes were also made at this time and the software was modified to accommodate these as well. During the welding process, critical weld parameters such as weld current and voltage, can give valuable information about the weld. In the past, weld data from the TIG welding process, such as the bagless transfer system in FB-Line, has been monitored using strip chart recorders. The data from the weld process, recorded on the strip chart recorder traces, are reviewed to analyze the weld. The OCWDAS improves this technology by digitizing the weld data which allows for automation of the analysis process. The OCWDAS performs the necessary functions to perform the data acquisition functions during the 3013 Outer Can Welding Process. It is important to monitor the critical weld parameters, current and voltage, during a weld as they can be used to set acceptance criteria for weld acceptance. The software monitors and records the weld current, voltage, and RPM data. It also records the absolute position of the weld head during the weld process from a quadrature encoder. Digital handshaking between the AMI Welding unit and the OCWDAS ensure that both systems are operational and ready prior to the weld initiation taking place.

  10. Nuclear Electric Propulsion for Outer Space Missions

    NASA Technical Reports Server (NTRS)

    Barret, Chris

    2003-01-01

    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.

  11. Lateral interactions in the outer retina

    PubMed Central

    Thoreson, Wallace B.; Mangel, Stuart C.

    2012-01-01

    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. PMID:22580106

  12. Nematic textures in spherical shells

    NASA Astrophysics Data System (ADS)

    Vitelli, V.; Nelson, D. R.

    2006-08-01

    The equilibrium texture of nematic shells is studied as a function of their thickness. For ultrathin shells the ground state has four short (1)/(2) disclination lines but, as the thickness of the film increases, a three-dimensional escaped configuration composed of two pairs of half-hedgehogs becomes energetically favorable. We derive an exact solution for the nematic ground state in the one Frank constant approximation and study the stability of the corresponding texture against thermal fluctuations.

  13. Core-shell-shell nanorods for controlled release of silver that can serve as a nanoheater for photothermal treatment on bacteria.

    PubMed

    Hu, Bo; Wang, Ning; Han, Lu; Chen, Ming-Li; Wang, Jian-Hua

    2015-01-01

    A novel bactericidal material comprising rod-shaped core-shell-shell Au-Ag-Au nanorods is constructed as a nanoheater in the near-infrared (NIR) region. The outer Au shell melts under laser irradiation and results in exposure of the inner Ag shell, facilitating the controlled release of the antibacterial Ag shell/layer or Ag(+). This results in the Au-Ag-Au nanorods having a favorable bactericidal ability as it combines the features of physical photothermal ablation sterilization of the outer Au shell and the antibacterial effect of the inner Ag shell or Ag(+) to the surrounding bacteria. The sterilizing ability of Au-Ag-Au nanorods is investigated with Escherichia coli O157:H7 as a model bacterial strain. Under low-power NIR laser irradiation (785 nm, 50 mW cm(-2)), the Au-Ag-Au nanoheater exhibits a higher photothermal conversion efficiency (with a solution temperature of 44C) with respect to that for the Au-Ag nanorods (39C). Meanwhile, a much improved stability with respect to Au-Ag nanorods is observed, i.e., 16 successive days of monitoring reveal virtually no change in the ultraviolet-visible spectrum of Au-Ag-Au nanorods, while a significant drop in absorption along with a 92 nm red shift of Localized Surface Plasmon Resonance is recorded for the Au-Ag nanorods. This brings an increasing bactericidal efficiency and long-term stability for the Au-Ag-Au nanorods. At a dosage of 10 ?g ml(-1), a killing rate of 100% is reached for the E. coli O157:H7 cells under 20 min of irradiation. The use of Au-Ag-Au nanorods avoids the abuse of broad-spectrum antibiotics and reduces the damage of tissues by alleviating the toxicity of silver under controlled release and by the use of low-power laser irradiation. These features could make the bimetallic core-shell-shell nanorods a favorable nanoheater for in vivo biomedical applications. PMID:25219350

  14. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

  15. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

  16. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

  17. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

  18. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed....

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

    NASA Technical Reports Server (NTRS)

    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

    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.

  20. Postmidnight chorus - A substorm phenomenon. [outer magnetosphere

    NASA Technical Reports Server (NTRS)

    Tsurutani, B. T.; Smith, E. J.

    1974-01-01

    The ELF emissions were detected in the midnight sector of the magnetosphere in conjunction with magnetospheric substorms. The emissions were observed at local midnight and early morning hours and are accordingly called 'post-midnight chorus.' The characteristics of these emissions such as their frequency time structure, emission frequency with respect to the local equatorial electron gyrofrequency, intensity-time variation, and the average intensity were investigated. The occurrence of the chorus in the nightside magnetosphere was investigated as a function of local time, L shell, magnetic latitude, and substorm activity, and the results of this analysis are presented. Specific features of postmidnight chorus are discussed in the context of possible wave-particle interactions occurring during magnetospheric substorms.

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

    SciTech Connect

    Moraes, Manoel; Diaz, Marcos E-mail: marcos@astro.iag.usp.br

    2009-12-15

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

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

    NASA Astrophysics Data System (ADS)

    Moraes, Manoel; Diaz, Marcos

    2009-12-01

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

  3. Slowly rotating thin shell gravastars

    NASA Astrophysics Data System (ADS)

    Uchikata, Nami; Yoshida, Shijun

    2016-01-01

    We construct the solutions of slowly rotating gravastars with a thin shell. In the zero-rotation limit, we consider the gravastar composed of a de Sitter core, a thin shell, and Schwarzschild exterior spacetime. The rotational effects are treated as small axisymmetric and stationary perturbations. The perturbed internal and external spacetimes are matched with a uniformly rotating thin shell. We assume that the angular velocity of the thin shell, ?, is much smaller than the Keplerian frequency of the nonrotating gravastar, {{{? }}}{{k}}. The solutions within an accuracy up to the second order of {{? }}/{{{? }}}{{k}} are obtained. The thin shell matter is assumed to be described by a perfect fluid and to satisfy the dominant energy condition in the zero-rotation limit. In this study, we assume that the equation of state for perturbations is the same as that of the unperturbed solution. The spherically symmetric component of the energy density perturbations, ? {? }0, is assumed to vanish independently of the rotation rate. Based on these assumptions, we obtain many numerical solutions and investigate properties of the rotational corrections to the structure of the thin shell gravastar.

  4. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  5. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  6. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  7. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  8. 7 CFR 201.57 - Hard seeds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... REGULATIONS Germination Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at..., are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra... percentage of germination. For flatpea, continue the swollen seed in test for 14 days when germinating at...

  9. PROTEIN COMPOSITION AND GRAIN HARDNESS IN SORGHUM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grain hardness is an important quality trait in sorghum. Grain hardness has been linked to milling and food quality as well as resistance to insects and mold. Despite the importance of grain hardness in sorghum, its biochemical basis is still not well understood. In sorghum, the grain is composed...

  10. 30 CFR 56.15002 - Hard hats.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Hard hats. 56.15002 Section 56.15002 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Personal Protection § 56.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or plant where falling...

  11. 30 CFR 57.15002 - Hard hats.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Hard hats. 57.15002 Section 57.15002 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or...

  12. 30 CFR 57.15002 - Hard hats.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Hard hats. 57.15002 Section 57.15002 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or...

  13. 30 CFR 56.15002 - Hard hats.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Hard hats. 56.15002 Section 56.15002 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Personal Protection § 56.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or plant where falling...

  14. 30 CFR 56.15002 - Hard hats.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Hard hats. 56.15002 Section 56.15002 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Personal Protection § 56.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or plant where falling...

  15. 30 CFR 57.15002 - Hard hats.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Hard hats. 57.15002 Section 57.15002 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or...

  16. 30 CFR 56.15002 - Hard hats.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Hard hats. 56.15002 Section 56.15002 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Personal Protection § 56.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or plant where falling...

  17. 30 CFR 56.15002 - Hard hats.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Hard hats. 56.15002 Section 56.15002 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Personal Protection § 56.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or plant where falling...

  18. 30 CFR 57.15002 - Hard hats.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Hard hats. 57.15002 Section 57.15002 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or...

  19. 30 CFR 57.15002 - Hard hats.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Hard hats. 57.15002 Section 57.15002 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... Underground § 57.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or...

  20. Warren G. Harding and the Press.

    ERIC Educational Resources Information Center

    Whitaker, W. Richard

    There are many parallels between the Richard M. Nixon administration and Warren G. Harding's term: both Republicans, both touched by scandal, and both having a unique relationship with the press. But in Harding's case the relationship was a positive one. One of Harding's first official acts as president was to restore the regular White House news

  1. Thermodynamic stability in elastic systems: Hard spheres embedded in a finite spherical elastic solid.

    PubMed

    Solano-Altamirano, J M; Goldman, Saul

    2015-12-01

    We determined the total system elastic Helmholtz free energy, under the constraints of constant temperature and volume, for systems comprised of one or more perfectly bonded hard spherical inclusions (i.e. "hard spheres") embedded in a finite spherical elastic solid. Dirichlet boundary conditions were applied both at the surface(s) of the hard spheres, and at the outer surface of the elastic solid. The boundary conditions at the surface of the spheres were used to describe the rigid displacements of the spheres, relative to their initial location(s) in the unstressed initial state. These displacements, together with the initial positions, provided the final shape of the strained elastic solid. The boundary conditions at the outer surface of the elastic medium were used to ensure constancy of the system volume. We determined the strain and stress tensors numerically, using a method that combines the Neuber-Papkovich spherical harmonic decomposition, the Schwartz alternating method, and Least-squares for determining the spherical harmonic expansion coefficients. The total system elastic Helmholtz free energy was determined by numerically integrating the elastic Helmholtz free energy density over the volume of the elastic solid, either by a quadrature, or a Monte Carlo method, or both. Depending on the initial position of the hard sphere(s) (or equivalently, the shape of the un-deformed stress-free elastic solid), and the displacements, either stationary or non-stationary Helmholtz free energy minima were found. The non-stationary minima, which involved the hard spheres nearly in contact with one another, corresponded to lower Helmholtz free energies, than did the stationary minima, for which the hard spheres were further away from one another. PMID:26701708

  2. Fault tolerant, radiation hard, high performance digital signal processor

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  3. Anion-dye-induced spectral sensitization of holographic microsystems core-silver halide shell

    NASA Astrophysics Data System (ADS)

    Tyurin, A. V.; Zhukov, S. A.; Churashov, V. P.; Bekshaev, A. Y.

    2015-11-01

    We have studied spectral sensitization with anionic dyes of holographic microsystems "core - silver halide shell" (CSHS), cores of which can be either nonsilver or silver halide compounds. Conditions under which dye sensitizers, being adsorbed on cores, remain under silver halide shells after their growing are considered. Comparison of results of sensitometric and low-temperature (T = 77 K) luminescent measurements have shown that these conditions are determined by the charge state of cations of microsystem cores. If the shell contains the same univalent component in its composition as the core does, as in the case in which the core is a silver halide compound, the anionic dye is displaced to the outer surface of the shell. If the core contains a divalent cationic component, as in the case in which the core is a nonsilver compound, the dye remains under the silver halide shell; i.e., it is overgrown by the shell. We have shown that the charge state of core cations affects the character of the core interaction with anionic dyes, which ensures differences in the spectral sensitization of CSHS microsystems, as well as differences in the dye photoexcitation relaxation in them. We have found that supersensitization of AgBr microcrystals sensitized by infrachromatic dye affects the interaction between the dye aggregates and the surface silver ions, which induces modification of the holographic microsystems' spectral sensitivity range.

  4. Shells in the C2 coma of Comet P/Halley

    NASA Technical Reports Server (NTRS)

    Schulz, Rita; A'Hearn, Michael F.

    1995-01-01

    We reanalyzed the CN images of Comet P/Halley, in which jets have been discovered for the first time, in search of shell structures. Shells were actually detected at the outer edges of the frames on those dates for which shells with radii small enough to be covered by the limited field of view of the CCD were predicted. The C2 images of the same data set were subjected to an analogous investigation which led to the discovery of shell structures in C2 as well. The morphology of the CN and the C2 shells is essentially equal on the same observational date. They have the same radii and show almost identical asymmetries which suggests that CN and C2 in the shells originate from the same general source. The comparison of the jets in both species before and after a two-dimensional continuum subtraction supports this supposition. The similar morphology of the jets indicates that both species are produced from the same bulk of precursor material which has been ejected in the form of jets from the same active area. However, similarly located and oriented jets in CN and C2 do not show similar relative intensities in most cases. These differences in the intensity distribution imply that the production rates of CN and C2 follow different laws.

  5. Spitzer/Infrared Array Camera near-infrared features in the outer parts of S4G galaxies

    NASA Astrophysics Data System (ADS)

    Laine, Seppo; Knapen, Johan H.; Muoz-Mateos, Juan-Carlos; Kim, Taehyun; Comern, Sbastien; Martig, Marie; Holwerda, Benne W.; Athanassoula, E.; Bosma, Albert; Johansson, Peter H.; Erroz-Ferrer, Santiago; Gadotti, Dimitri A.; de Paz, Armando Gil; Hinz, Joannah; Laine, Jarkko; Laurikainen, Eija; Menndez-Delmestre, Karn; Mizusawa, Trisha; Regan, Michael W.; Salo, Heikki; Sheth, Kartik; Seibert, Mark; Buta, Ronald J.; Cisternas, Mauricio; Elmegreen, Bruce G.; Elmegreen, Debra M.; Ho, Luis C.; Madore, Barry F.; Zaritsky, Dennis

    2014-11-01

    We present a catalogue and images of visually detected features, such as asymmetries, extensions, warps, shells, tidal tails, polar rings, and obvious signs of mergers or interactions, in the faint outer regions (at and outside of R25) of nearby galaxies. This catalogue can be used in future quantitative studies that examine galaxy evolution due to internal and external factors. We are able to reliably detect outer region features down to a brightness level of 0.03 MJy sr-1 pixel-1 at 3.6 ?m in the Spitzer Survey of Stellar Structure in Galaxies (S4G). We also tabulate companion galaxies. We find asymmetries in the outer isophotes in 22 1 per cent of the sample. The asymmetry fraction does not correlate with galaxy classification as an interacting galaxy or merger remnant, or with the presence of companions. We also compare the detected features to similar features in galaxies taken from cosmological zoom re-simulations. The simulated images have a higher fraction (33 per cent) of outer disc asymmetries, which may be due to selection effects and an uncertain star formation threshold in the models. The asymmetries may have either an internal (e.g. lopsidedness due to dark halo asymmetry) or external origin.

  6. The hard problem of cooperation.

    PubMed

    Eriksson, Kimmo; Strimling, Pontus

    2012-01-01

    Based on individual variation in cooperative inclinations, we define the "hard problem of cooperation" as that of achieving high levels of cooperation in a group of non-cooperative types. Can the hard problem be solved by institutions with monitoring and sanctions? In a laboratory experiment we find that the answer is affirmative if the institution is imposed on the group but negative if development of the institution is left to the group to vote on. In the experiment, participants were divided into groups of either cooperative types or non-cooperative types depending on their behavior in a public goods game. In these homogeneous groups they repeatedly played a public goods game regulated by an institution that incorporated several of the key properties identified by Ostrom: operational rules, monitoring, rewards, punishments, and (in one condition) change of rules. When change of rules was not possible and punishments were set to be high, groups of both types generally abided by operational rules demanding high contributions to the common good, and thereby achieved high levels of payoffs. Under less severe rules, both types of groups did worse but non-cooperative types did worst. Thus, non-cooperative groups profited the most from being governed by an institution demanding high contributions and employing high punishments. Nevertheless, in a condition where change of rules through voting was made possible, development of the institution in this direction was more often voted down in groups of non-cooperative types. We discuss the relevance of the hard problem and fit our results into a bigger picture of institutional and individual determinants of cooperative behavior. PMID:22792282

  7. The Hard Problem of Cooperation

    PubMed Central

    Eriksson, Kimmo; Strimling, Pontus

    2012-01-01

    Based on individual variation in cooperative inclinations, we define the hard problem of cooperation as that of achieving high levels of cooperation in a group of non-cooperative types. Can the hard problem be solved by institutions with monitoring and sanctions? In a laboratory experiment we find that the answer is affirmative if the institution is imposed on the group but negative if development of the institution is left to the group to vote on. In the experiment, participants were divided into groups of either cooperative types or non-cooperative types depending on their behavior in a public goods game. In these homogeneous groups they repeatedly played a public goods game regulated by an institution that incorporated several of the key properties identified by Ostrom: operational rules, monitoring, rewards, punishments, and (in one condition) change of rules. When change of rules was not possible and punishments were set to be high, groups of both types generally abided by operational rules demanding high contributions to the common good, and thereby achieved high levels of payoffs. Under less severe rules, both types of groups did worse but non-cooperative types did worst. Thus, non-cooperative groups profited the most from being governed by an institution demanding high contributions and employing high punishments. Nevertheless, in a condition where change of rules through voting was made possible, development of the institution in this direction was more often voted down in groups of non-cooperative types. We discuss the relevance of the hard problem and fit our results into a bigger picture of institutional and individual determinants of cooperative behavior. PMID:22792282

  8. Making Nozzles From Hard Materials

    NASA Technical Reports Server (NTRS)

    Wells, Dennis L.

    1989-01-01

    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.

  9. Hard Scattering Studies at Jlab

    SciTech Connect

    Harutyun Avagyan; Peter Bosted; Volker Burkert; Latifa Elouadrhiri

    2005-09-01

    We present current activities and future prospects for studies of hard scattering processes using the CLAS detector and the CEBAF polarized electron beam. Kinematic dependences of single and double spin asymmetries have been measured in a wide kinematic range at CLAS with a polarized NH{sub 3} and unpolarized liquid hydrogen targets. It has been shown that the data are consistent with factorization and observed target and beam asymmetries are in good agreement with measurements performed at higher energies, suggesting that the high energy-description of the semi-inclusive DIS process can be extended to the moderate energies of JLab measurements.

  10. Corrugated outer sheath gas-insulated transmission line

    DOEpatents

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

    1981-01-01

    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.

  11. Corrugated outer sheath gas-insulated transmission line

    SciTech Connect

    Kemeny, G.A.; Cookson, A.H.

    1981-09-08

    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 there between. 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. 8 figs.

  12. Air cleaner shell noise analysis with plate and shell theory

    SciTech Connect

    White, J.A. Jr.

    1996-09-01

    Plate and shell theory is used to determine the force vibration response of large air cleaner surfaces for the air cleaner breathing modes of vibration. Plate equations are small and can be programmed into a hand held calculator for convenience. The eigenfunction method is used to solve the plate equation to obtain the plate vibration response. Surface reinforcements such as ribs, corrugation and surface curvature are included in the plate equation in terms of structural rigidity. Surface stiffness can be modified by simply changing the stiffener moment of inertia or by changing the number of stiffeners. The approximation technique was used to model a rectangular shallow shell. The predicted shell first natural frequency compared favorably to that of an exact solution to the shallow shell equation. Two air cleaner covers were modeled with the technique. One of the covers was flat and reinforced with ribs while the other was a shallow shell also reinforced with ribs. Forced vibration and frequency predictions of the air cleaner cover breathing mode compared well with experimental data.

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

    NASA Astrophysics Data System (ADS)

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

    2000-06-01

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

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

    PubMed

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

    2000-06-29

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

  15. The Electron Shell and Alpha Decay in Super-Heavy Nuclei

    NASA Astrophysics Data System (ADS)

    Igashov, S. Yu.; Tchuvil'Sky, Yu. M.

    2015-11-01

    The influence of the electron shell on the characteristics of the alpha decay of the 294118 isotope, as an example of a super-heavy atom, is studied theoretically. The calculation is based on direct solution of the Schrdinger equation. The rigorous quantum-mechanical approach being developed makes possible the outer boundary condition of the alpha-particle diverging wave to be taken into account properly. The effect under discussion depends on the behavior of the function of electron density both in the classically-forbidden and the classically-allowed areas of alpha-particle motion. A principally new effect - increasing of the decay rate originated by the part of electron shell located in the classically-allowed area - is revealed in the chosen example. The influence of relativistic properties of inner electrons, scenario of penetration of the alpha-particle through the atomic shell and finite size of nucleus are also studied.

  16. CuGaS2 hollow spheres from Ga-CuS core-shell nanoparticles.

    PubMed

    Cha, Ji-Hyun; Jung, Duk-Young

    2014-05-01

    A liquid gallium emulsion was prepared as a starting material using ultrasound treatment in ethylene glycol. Core-shell particles of Ga@CuS were successfully synthesized by deposition of a CuS layer on gallium droplets through sonochemical deposition of copper ions and thiourea in an alcohol media. The core and shell of Ga@CuS products were composed of amorphous gallium metal and covellite phase CuS, which transformed into chalcopyrite CuGaS2 hollow spheres after sulfurization at 450°C, which was the lowest crystallization temperature. The formation of hollow nanostructures was ascribed to the Kirkendall mechanism, in which liquid gallium particles play an important role as reactive templates. In conclusion, we obtained CuGaS2 hollow spheres with a 430 nm outer diameter and 120 nm shell thickness that had the same crystal structure and electrical properties as bulk CuGaS2. PMID:24365224

  17. Tectonics of the Outer Planet Satellites

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

  18. Biogenesis of outer membranes in Gram-negative bacteria.

    PubMed

    Tokuda, Hajime

    2009-03-23

    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

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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.

  20. A model for cochlear outer hair cell deformations in micropipette aspiration experiments: an analytical solution.

    PubMed

    Spector, A A; Brownell, W E; Popel, A S

    1996-01-01

    We propose a mathematical model to describe the deformations of the cochlear outer hair cell (OHC) in the micropipette aspiration experiments. The bending effect is considered, and the OHC is treated as a cylindrical shell. The pipette effect is modeled by two-dimensional normal loading. Considering the OHC wall as an infinitely long cylinder, we obtain solution in terms of Fourier series with respect to the circumferential coordinate where coefficients are expressed by closed formulae. We keep leading terms in Fourier series and derive a closed formula for the length of tongue of the aspirated cell surface in terms of pipette pressure, cell geometry, and elastic moduli. To demonstrate application of the theory, we use data recently reported from the micropipette aspiration experiments and obtain an estimate of the elastic shear modulus for the OHC lateral wall. PMID:8841728

  1. Local hardness equalization: Exploiting the ambiguity

    NASA Astrophysics Data System (ADS)

    Ayers, Paul W.; Parr, Robert G.

    2008-05-01

    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.

  2. Hardness correlation for uranium and its alloys

    SciTech Connect

    Humphreys, D L; Romig, Jr, A D

    1983-03-01

    The hardness of 16 different uranium-titanium (U-Ti) alloys was measured on six (6) different hardness scales (R/sub A/, R/sub B/, R/sub C/, R/sub D/, Knoop, and Vickers). The alloys contained between 0.75 and 2.0 wt % Ti. All of the alloys were solutionized (850/sup 0/C, 1 h) and ice-water quenched to produce a supersaturated martensitic phase. A range of hardnesses was obtained by aging the samples for various times and temperatures. The correlation of various hardness scales was shown to be virtually identical to the hardness-scale correlation for steels. For more-accurate conversion from one hardness scale to another, least-squares-curve fits were determined for the various hardness-scale correlations. 34 figures, 5 tables.

  3. The Magnetic Field in the Outer Heliosphere

    NASA Technical Reports Server (NTRS)

    Suess, S. T.

    2004-01-01

    One of the great achievements of Parker was the prediction that the solar magnetic field would be drawn into Archimedian spirals as it is carried away from the Sun by the solar wind. This prediction has been amply confirmed by many in situ measurements in the intervening four decades. But, Parker made his prediction for a solar wind that expands into infinite space while we now know that the local interstellar medium (LISM) is far from empty and, in fact, confines the solar wind to a finite volume, known as the heliosphere, that extends to approximately 100 AU in the upstream direction (the solar system is moving through the LISM). Voyagers 1/2, presently at -80 AU, are approaching the upstream boundaries of the heliosphere and returning data on the properties of the magnetic field. This is important for understanding how galactic cosmic rays (GCRs) reach the Earth. Voyagers show that the IMF at 10-80 AU behaves much as Parker predicted - with two important exceptions. This is not surprising since the field is essentially passively advected by the solar wind out to 80 AU. But, new models say that nearer the heliosphere boundaries the field plays a major role in the solar wind-LISM interaction. However, of the many physical ingredients that constitute the outer heliosphere, the magnetic field poses some of the most interesting and difficult numerical modeling problems. Presently, only a few results have been published and much remains to be done. Here I will summarize the expected and measured behavior of the magnetic field at 80 AU. Then I will describe modeling predictions beyond 80 AU: magnetic "tornadoes", polarity envelopes, the Axford-Cranfill effect, inner and outer magnetic walls and more. I will also list what I believe to be important new modeling objectives. Finally, I will speculate on what is happening with the magnetic field near the nose of the heliosphere. My conclusion is that models of GCR modulation rarely incorporate even crudely realistic magnetic fields so it is a wonder that they are as successful as they are and no surprise that there are still important discrepancies between GCR modulation observations and the models.

  4. Are Short GRBs Really Hard?

    NASA Astrophysics Data System (ADS)

    Sakamoto, T.; Barbier, L.; Barthelmy, S.; Cummings, J.; Fenimore, E.; Gehrels, N.; Hullinger, D.; Krimm, H.; Markwardt, C.; Palmer, D.; Parsons, A.; Sato, G.; Tueller, J.; Aptekar, R.; Cline, T.; Golenetskii, S.; Mazets, E.; Pal'Shin, V.; Ricker, G.; Lamb, D.; Atteia, J.-L.; Swift-Bat; Konus-Wind; Hete-2 Team

    2006-05-01

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

  5. Hard and Soft Safety Verifications

    NASA Technical Reports Server (NTRS)

    Wetherholt, Jon; Anderson, Brenda

    2012-01-01

    The purpose of this paper is to examine the differences between and the effects of hard and soft safety verifications. Initially, the terminology should be defined and clarified. A hard safety verification is datum which demonstrates how a safety control is enacted. An example of this is relief valve testing. A soft safety verification is something which is usually described as nice to have but it is not necessary to prove safe operation. An example of a soft verification is the loss of the Solid Rocket Booster (SRB) casings from Shuttle flight, STS-4. When the main parachutes failed, the casings impacted the water and sank. In the nose cap of the SRBs, video cameras recorded the release of the parachutes to determine safe operation and to provide information for potential anomaly resolution. Generally, examination of the casings and nozzles contributed to understanding of the newly developed boosters and their operation. Safety verification of SRB operation was demonstrated by examination for erosion or wear of the casings and nozzle. Loss of the SRBs and associated data did not delay the launch of the next Shuttle flight.

  6. From core/shell to hollow Fe/γ-Fe2O3 nanoparticles: evolution of the magnetic behavior

    NASA Astrophysics Data System (ADS)

    Nemati, Z.; Khurshid, H.; Alonso, J.; Phan, M. H.; Mukherjee, P.; Srikanth, H.

    2015-10-01

    High quality Fe/γ-Fe2O3 core/shell, core/void/shell, and hollow nanoparticles with two different sizes of 8 and 12 nm were synthesized, and the effect of morphology, surface and finite-size effects on their magnetic properties including the exchange bias (EB) effect were systematically investigated. We find a general trend for both systems that as the morphology changes from core/shell to core/void/shell, the magnetization of the system decays and inter-particle interactions become weaker, while the effective anisotropy and the EB effect increase. The changes are more drastic when the nanoparticles become completely hollow. Noticeably, the morphological change from core/shell to hollow increases the mean blocking temperature for the 12 nm particles but decreases for the 8 nm particles. The low-temperature magnetic behavior of the 12 nm particles changes from a collective super-spin-glass system mediated by dipolar interactions for the core/shell nanoparticles to a frustrated cluster glass-like state for the shell nanograins in the hollow morphology. On the other hand for the 8 nm nanoparticles core/shell and hollow particles the magnetic behavior is more similar, and a conventional spin glass-like transition is obtained at low temperatures. In the case of the hollow nanoparticles, the coupling between the inner and outer spin layers in the shell gives rise to an enhanced EB effect, which increases with increasing shell thickness. This indicates that the morphology of the shell plays a crucial role in this kind of exchange-biased systems.

  7. From core/shell to hollow Fe/γ-Fe₂O₃ nanoparticles: evolution of the magnetic behavior.

    PubMed

    Nemati, Z; Khurshid, H; Alonso, J; Phan, M H; Mukherjee, P; Srikanth, H

    2015-10-01

    High quality Fe/γ-Fe2O3 core/shell, core/void/shell, and hollow nanoparticles with two different sizes of 8 and 12 nm were synthesized, and the effect of morphology, surface and finite-size effects on their magnetic properties including the exchange bias (EB) effect were systematically investigated. We find a general trend for both systems that as the morphology changes from core/shell to core/void/shell, the magnetization of the system decays and inter-particle interactions become weaker, while the effective anisotropy and the EB effect increase. The changes are more drastic when the nanoparticles become completely hollow. Noticeably, the morphological change from core/shell to hollow increases the mean blocking temperature for the 12 nm particles but decreases for the 8 nm particles. The low-temperature magnetic behavior of the 12 nm particles changes from a collective super-spin-glass system mediated by dipolar interactions for the core/shell nanoparticles to a frustrated cluster glass-like state for the shell nanograins in the hollow morphology. On the other hand for the 8 nm nanoparticles core/shell and hollow particles the magnetic behavior is more similar, and a conventional spin glass-like transition is obtained at low temperatures. In the case of the hollow nanoparticles, the coupling between the inner and outer spin layers in the shell gives rise to an enhanced EB effect, which increases with increasing shell thickness. This indicates that the morphology of the shell plays a crucial role in this kind of exchange-biased systems. PMID:26376675

  8. The effects of laterally varying icy shell structure on the tidal response of Europa and Ganymede

    NASA Astrophysics Data System (ADS)

    Wahr, J. M.; A, G.; Zhong, S.

    2013-12-01

    One of the long-sought objectives of an icy moon orbiter or fly-by mission, has been to use tidal observations to help determine the existence of a liquid ocean and characteristics of the overlying icy shell. The radio science component of such a mission could be used to estimate the tidal potential Love number k2 for gravity. And if there is an on-board laser altimeter, it could be used to determine the radial displacement Love number h2. Knowledge of either of those Love numbers could provide information on the presence of an ocean beneath the icy outer shell, and the two Love numbers could be combined to place constraints on the thickness of the icy shell. Though if a subsurface ocean exists, complications could conceivably arise if the icy outer shell has significant lateral variations in elastic thickness or shear modulus, or if the ocean is not global in extent so that the icy shell is grounded in places but floating in others. In these cases, the tidal deformation pattern would not be represented as the sum of degree 2 harmonics, and so the results could not be characterized in terms of a single Love number. In this study, by solving a set of tidal loading problems with laterally variable icy shell structures (for which the existence of an ocean layer is assumed), we investigate how those structures might complicate the interpretation of the tide measurements, and we discuss how to extract information regarding the interior structure of Ganymede and Europa from measurements of their tidal response.

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

    SciTech Connect

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

    2006-06-30

    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.

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

    PubMed Central

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

    2011-01-01

    Obligate brood parasitic birds lay their eggs in nests of other species and parasite eggs typically have evolved greater structural strength relative to host eggs. Increased mechanical strength of the parasite eggshell is an adaptation that can interfere with puncture ejection behaviours of discriminating hosts. We investigated whether hardness of eggshells is related to differences between physical and chemical traits from three different races of the parasitic common cuckoo Cuculus canorus, and their respective hosts. Using tools developed for materials science, we discovered a novel correlate of increased strength of parasite eggs: the common cuckoo's egg exhibits a greater microhardness, especially in the inner region of the shell matrix, relative to its host and sympatric non-host species. We then tested predictions of four potential mechanisms of shell strength: (i) increased relative thickness overall, (ii) greater proportion of the structurally harder shell layers, (iii) higher concentration of inorganic components in the shell matrix, and (iv) elevated deposition of a high density compound, MgCO3, in the shell matrix. We confirmed support only for hypothesis (i). Eggshell characteristics did not differ between parasite eggs sampled from different host nests in distant geographical sites, suggesting an evolutionarily shared microstructural mechanism of stronger parasite eggshells across diverse host-races of brood parasitic cuckoos. PMID:21561966

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

    NASA Technical Reports Server (NTRS)

    Schenk, Paul; Mimmo, Francis; Prockter, Louise

    2004-01-01

    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.

  12. Outer membrane vesicles as platform vaccine technology

    PubMed Central

    Stork, Michiel; van der Ley, Peter

    2015-01-01

    Abstract Outer membrane vesicles (OMVs) are released spontaneously during growth by many Gram‐negative bacteria. They present a range of surface antigens in a native conformation and have natural properties like immunogenicity, self‐adjuvation and uptake by immune cells which make them attractive for application as vaccines against pathogenic bacteria. In particular with Neisseria meningitidis, they have been investigated extensively and an OMV‐containing meningococcal vaccine has recently been approved by regulatory agencies. Genetic engineering of the OMV‐producing bacteria can be used to improve and expand their usefulness as vaccines. Recent work on meningitis B vaccines shows that OMVs can be modified, such as for lipopolysaccharide reactogenicity, to yield an OMV product that is safe and effective. The overexpression of crucial antigens or simultaneous expression of multiple antigenic variants as well as the expression of heterologous antigens enable expansion of their range of applications. In addition, modifications may increase the yield of OMV production and can be combined with specific production processes to obtain high amounts of well‐defined, stable and uniform OMV particle vaccine products. Further improvement can facilitate the development of OMVs as platform vaccine product for multiple applications. PMID:26912077

  13. Magnetic Field in the Outer Heliosphere

    NASA Technical Reports Server (NTRS)

    Smith, Edward J.

    2004-01-01

    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.

  14. The Outer Heliosphere: The Next Frontier

    NASA Astrophysics Data System (ADS)

    Heber, B.; Zank, G. P.

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

  15. The Outer Heliosphere: The Next Frontiers

    NASA Astrophysics Data System (ADS)

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

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

  16. Meridional plasma flow in the outer heliosphere

    SciTech Connect

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

    1988-12-01

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

  17. Thermal plasma in outer planet magnetospheres

    NASA Technical Reports Server (NTRS)

    Belcher, J. W.; Mcnutt, R. L., Jr.; Richardson, J. D.

    1990-01-01

    The plasma environments of the outer planets are a study in contrasts. The magnetosphere of Jupiter is dominated by the prodigious plasma output of Io, with losses due to diffusion driven by mass loading. At Saturn, the small icy satellites are the major sources of plasma for the inner magnetosphere. The low mass loading rates there imply that the densities of the plasma tori are limited by dissociative recombination, rather than diffusive transport. At Uranus, the icy satellites are negligible plasma sources compared to the input from the extended neutral hydrogen cloud and the ionosphere. Convection driven by the solar wind penetrates deep into the inner magnetosphere because of the unique orientation of the rotation axis of Uranus. The expected magnetosphere of Neptune is similar to that of Saturn and Jupiter, with Triton, the ring arcs, and the planet as possible plasma sources. The Voyager 2 encounter with Neptune holds out the hope of a passage through a nonterrestrial auroral region, a unique event in planetary exploration.

  18. THE OUTER MAGNETIC FIELD OF L183

    SciTech Connect

    Clemens, Dan P.

    2012-03-20

    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.

  19. Infrared observations of outer planet satellites

    NASA Astrophysics Data System (ADS)

    Johnson, T. V.

    1988-08-01

    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.

  20. Bacterial Outer Membrane Vesicles and Vaccine Applications

    PubMed Central

    Acevedo, Reinaldo; Fernndez, 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

    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. PMID:24715891