Nuclear reactor alignment plate configuration

DOEpatents

Altman, David A; Forsyth, David R; Smith, Richard E; Singleton, Norman R

2014-01-28

An alignment plate that is attached to a core barrel of a pressurized water reactor and fits within slots within a top plate of a lower core shroud and upper core plate to maintain lateral alignment of the reactor internals. The alignment plate is connected to the core barrel through two vertically-spaced dowel pins that extend from the outside surface of the core barrel through a reinforcement pad and into corresponding holes in the alignment plate. Additionally, threaded fasteners are inserted around the perimeter of the reinforcement pad and into the alignment plate to further secure the alignment plate to the core barrel. A fillet weld also is deposited around the perimeter of the reinforcement pad. To accomodate thermal growth between the alignment plate and the core barrel, a gap is left above, below and at both sides of one of the dowel pins in the alignment plate holes through with the dowel pins pass.

The Structure of a BamA-BamD Fusion Illuminates the Architecture of the β-Barrel Assembly Machine Core.

PubMed

Bergal, Hans Thor; Hopkins, Alex Hunt; Metzner, Sandra Ines; Sousa, Marcelo Carlos

2016-02-02

The β-barrel assembly machine (BAM) mediates folding and insertion of integral β-barrel outer membrane proteins (OMPs) in Gram-negative bacteria. Of the five BAM subunits, only BamA and BamD are essential for cell viability. Here we present the crystal structure of a fusion between BamA POTRA4-5 and BamD from Rhodothermus marinus. The POTRA5 domain binds BamD between its tetratricopeptide repeats 3 and 4. The interface structural elements are conserved in the Escherichia coli proteins, which allowed structure validation by mutagenesis and disulfide crosslinking in E. coli. Furthermore, the interface is consistent with previously reported mutations that impair BamA-BamD binding. The structure serves as a linchpin to generate a BAM model where POTRA domains and BamD form an elongated periplasmic ring adjacent to the membrane with a central cavity approximately 30 × 60 Å wide. We propose that nascent OMPs bind this periplasmic ring prior to insertion and folding by BAM. Copyright © 2016 Elsevier Ltd. All rights reserved.

Biogenesis of the mitochondrial TOM complex: Mim1 promotes insertion and assembly of signal-anchored receptors.

PubMed

Becker, Thomas; Pfannschmidt, Sylvia; Guiard, Bernard; Stojanovski, Diana; Milenkovic, Dusanka; Kutik, Stephan; Pfanner, Nikolaus; Meisinger, Chris; Wiedemann, Nils

2008-01-04

The translocase of the outer membrane (TOM complex) is the central entry gate for nuclear-encoded mitochondrial precursor proteins. All Tom proteins are also encoded by nuclear genes and synthesized as precursors in the cytosol. The channel-forming beta-barrel protein Tom40 is targeted to mitochondria via Tom receptors and inserted into the outer membrane by the sorting and assembly machinery (SAM complex). A further outer membrane protein, Mim1, plays a less defined role in assembly of Tom40 into the TOM complex. The three receptors Tom20, Tom22, and Tom70 are anchored in the outer membrane by a single transmembrane alpha-helix, located at the N terminus in the case of Tom20 and Tom70 (signal-anchored) or in the C-terminal portion in the case of Tom22 (tail-anchored). Insertion of the precursor of Tom22 into the outer membrane requires pre-existing Tom receptors while the import pathway of the precursors of Tom20 and Tom70 is only poorly understood. We report that Mim1 is required for efficient membrane insertion and assembly of Tom20 and Tom70, but not Tom22. We show that Mim1 associates with SAM(core) components to a large SAM complex, explaining its role in late steps of the assembly pathway of Tom40. We conclude that Mim1 is not only required for biogenesis of the beta-barrel protein Tom40 but also for membrane insertion and assembly of signal-anchored Tom receptors. Thus, Mim1 plays an important role in the efficient assembly of the mitochondrial TOM complex.

Evaluating Long-Term Impacts of Soil-Mixing Source-Zone Treatment using Cryogenic Core Collection

DTIC Science & Technology

2017-06-01

to (a) coring equipment freezing downhole, (b) freezing or binding of the core sample in barrel, and ( c ) running out of LN in the vicinity of sampling...encountered due to (a) coring equipment freezing downhole, (b) freezing or binding of the core sample in barrel, and ( c ) running out of LN in the...equipment freezing downhole, (b) freezing or binding of the core sample in barrel, and ( c ) running out of LN in the vicinity of sampling. Downhole

Cooling of weapons with graphite foam

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

Klett, James W.; Trammell, Michael P.

Disclosed are examples of an apparatus for cooling a barrel 12 of a firearm 10 and examples of a cooled barrel assembly 32 for installation into an existing firearm 10. When assembled with the barrel 12, a contact surface 16 of a shell 14 is proximate to, and in thermal communication with, the outer surface of the barrel 18. The shell 14 is formed of commercially available or modified graphite foam.

Refolding, crystallization and preliminary X-ray crystallographic studies of the β-barrel domain of BamA, a membrane protein essential for outer membrane protein biogenesis.

PubMed

Ni, Dongchun; Yang, Kun; Huang, Yihua

2014-03-01

In Gram-negative bacteria, the assembly of outer membrane proteins (OMPs) requires a five-protein β-barrel assembly machinery (BAM) complex, of which BamA is an essential and evolutionarily conserved integral outer membrane protein. Here, the refolding, crystallization and preliminary X-ray crystallographic characterization of the β-barrel domain of BamA from Escherichia coli (EcBamA) are reported. Native and selenomethionine-substituted EcBamA proteins were crystallized at 16°C and X-ray diffraction data were collected to 2.6 and 3.7 Å resolution, respectively. The native crystals belonged to space group P21212, with unit-cell parameters a = 118.492, b = 159.883, c = 56.000 Å and two molecules in one asymmetric unit; selenomethionine-substituted protein crystals belonged to space group P4322, with unit-cell parameters a = b = 163.162, c = 46.388 Å and one molecule in one asymmetric unit. Initial phases for EcBamA β-barrel domain were obtained from a SeMet SAD data set. These preliminary X-ray crystallographic studies paved the way for further structural determination of the β-barrel domain of EcBamA.

The presequence pathway is involved in protein sorting to the mitochondrial outer membrane.

PubMed

Wenz, Lena-Sophie; Opaliński, Lukasz; Schuler, Max-Hinderk; Ellenrieder, Lars; Ieva, Raffaele; Böttinger, Lena; Qiu, Jian; van der Laan, Martin; Wiedemann, Nils; Guiard, Bernard; Pfanner, Nikolaus; Becker, Thomas

2014-06-01

The mitochondrial outer membrane contains integral α-helical and β-barrel proteins that are imported from the cytosol. The machineries importing β-barrel proteins have been identified, however, different views exist on the import of α-helical proteins. It has been reported that the biogenesis of Om45, the most abundant signal-anchored protein, does not depend on proteinaceous components, but involves direct insertion into the outer membrane. We show that import of Om45 occurs via the translocase of the outer membrane and the presequence translocase of the inner membrane. Assembly of Om45 in the outer membrane involves the MIM machinery. Om45 thus follows a new mitochondrial biogenesis pathway that uses elements of the presequence import pathway to direct a protein to the outer membrane. © 2014 The Authors.

Characterization of the targeting signal in mitochondrial β-barrel proteins

PubMed Central

Jores, Tobias; Klinger, Anna; Groß, Lucia E.; Kawano, Shin; Flinner, Nadine; Duchardt-Ferner, Elke; Wöhnert, Jens; Kalbacher, Hubert; Endo, Toshiya; Schleiff, Enrico; Rapaport, Doron

2016-01-01

Mitochondrial β-barrel proteins are synthesized on cytosolic ribosomes and must be specifically targeted to the organelle before their integration into the mitochondrial outer membrane. The signal that assures such precise targeting and its recognition by the organelle remained obscure. In the present study we show that a specialized β-hairpin motif is this long searched for signal. We demonstrate that a synthetic β-hairpin peptide competes with the import of mitochondrial β-barrel proteins and that proteins harbouring a β-hairpin peptide fused to passenger domains are targeted to mitochondria. Furthermore, a β-hairpin motif from mitochondrial proteins targets chloroplast β-barrel proteins to mitochondria. The mitochondrial targeting depends on the hydrophobicity of the β-hairpin motif. Finally, this motif interacts with the mitochondrial import receptor Tom20. Collectively, we reveal that β-barrel proteins are targeted to mitochondria by a dedicated β-hairpin element, and this motif is recognized at the organelle surface by the outer membrane translocase. PMID:27345737

46th Annual Gun and Missile Systems Conference and Exhibition. Volume 3 - Thursday

DTIC Science & Technology

2011-09-01

Grade Sensors Through Use of Accelerated Aging Principles Mr. Scott Gift 11657 Modeling of the Autofrettage Processes of a Gun Barrel Mr. Sudhir...Emissions Measured on the Outer Portion of a Composite Barrel Ms. Rushie Ghimire GUN & MISSILE SYSTEMS ADDITIONAL AUTHORS GUN & MISSILE SYSTEMS...Transportation – Loading – Gun Fire to Barrel Exit – After Barrel Exit • Passing: Fuze safety devices remain safe; safe for disposal or safe for

BamA β16C strand and periplasmic turns are critical for outer membrane protein insertion and assembly.

PubMed

Gu, Yinghong; Zeng, Yi; Wang, Zhongshan; Dong, Changjiang

2017-11-21

Outer membrane (OM) β-barrel proteins play important roles in importing nutrients, exporting wastes and conducting signals in Gram-negative bacteria, mitochondria and chloroplasts. The outer membrane proteins (OMPs) are inserted and assembled into the OM by OMP85 family proteins. In Escherichia coli , the β-barrel assembly machinery (BAM) contains four lipoproteins such as BamB, BamC, BamD and BamE, and one OMP BamA, forming a 'top hat'-like structure. Structural and functional studies of the E. coli BAM machinery have revealed that the rotation of periplasmic ring may trigger the barrel β1C-β6C scissor-like movement that promote the unfolded OMP insertion without using ATP. Here, we report the BamA C-terminal barrel structure of Salmonella enterica Typhimurium str. LT2 and functional assays, which reveal that the BamA's C-terminal residue Trp, the β16C strand of the barrel and the periplasmic turns are critical for the functionality of BamA. These findings indicate that the unique β16C strand and the periplasmic turns of BamA are important for the outer membrane insertion and assembly. The periplasmic turns might mediate the rotation of the periplasmic ring to the scissor-like movement of BamA β1C-β6C, triggering the OMP insertion. These results are important for understanding the OMP insertion in Gram-negative bacteria, as well as in mitochondria and chloroplasts. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Augmenting β-augmentation: structural basis of how BamB binds BamA and may support folding of outer membrane proteins.

PubMed

Heuck, Alexander; Schleiffer, Alexander; Clausen, Tim

2011-03-11

β-Barrel proteins are frequently found in the outer membrane of mitochondria, chloroplasts and Gram-negative bacteria. In Escherichia coli, these proteins are inserted in the outer membrane by the Bam (β-barrel assembly machinery) complex, a multiprotein machinery formed by the β-barrel protein BamA and the four peripheral membrane proteins BamB, BamC, BamD and BamE. The periplasmic part of BamA binds prefolded β-barrel proteins by a β-augmentation mechanism, thereby stabilizing the precursors prior to their membrane insertion. However, the role of the associated proteins within the Bam complex remains unknown. Here, we describe the crystal structure of BamB, a nonessential component of the Bam complex. The structure shows a typical eight-bladed β-propeller fold. Two sequence stretches of BamB were previously identified to be important for interaction with BamA. In our structure, both motifs are located in close proximity to each other and contribute to a conserved region forming a narrow groove on the top of the propeller. Moreover, crystal contacts reveal two interaction modes of how BamB might bind unfolded β-barrel proteins. In the crystal lattice, BamB binds to exposed β-strands by β-augmentation, whereas peptide stretches rich in aromatic residues can be accommodated in hydrophobic pockets located at the bottom of the propeller. Thus, BamB could simultaneously bind to BamA and prefolded β-barrel proteins, thereby enhancing the folding and membrane insertion capability of the Bam complex. Copyright © 2011 Elsevier Ltd. All rights reserved.

A wireline piston core barrel for sampling cohesionless sand and gravel below the water table

USGS Publications Warehouse

Zapico, Michael M.; Vales, Samuel; Cherry, John A.

1987-01-01

A coring device has been developed to obtain long and minimally disturbed samples of saturated cohesionless sand and gravel. The coring device, which includes a wireline and piston, was developed specifically for use during hollow-stem auger drilling but it also offers possibilities for cable tool and rotary drilling. The core barrel consists of an inner liner made of inexpensive aluminum or plastic tubing, a piston for core recovery, and an exterior steel housing that protects the liner when the core barrel is driven into the aquifer. The core barrel, which is approximately 1.6m (5.6 feet) long, is advanced ahead of the lead auger by hammering at the surface on drill rods that are attached to the core barrel. After the sampler has been driven 1.5m (5 feet), the drill rods are detached and a wireline is used to hoist the core barrel, with the sample contained in the aluminum or plastic liner, to the surface. A vacuum developed by the piston during the coring operation provides good recovery of both the sediment and aquifer fluids contained in the sediment. In the field the sample tubes can be easily split along their length for on-site inspection or they can be capped with the pore water fluids inside and transported to the laboratory. The cores are 5cm (2 inches) in diameter by 1.5m (5 feet) long. Core acquisition to depths of 35m (115 feet), with a recovery greater than 90 percent, has become routine in University of Waterloo aquifer studies. A large diameter (12.7cm [5 inch]) version has also been used successfully. Nearly continuous sample sequences from sand and gravel aquifers have been obtained for studies of sedimentology, hydraulic conductivity, hydrogeochemistry and microbiology.

A Peptidomimetic Antibiotic Targets Outer Membrane Proteins and Disrupts Selectively the Outer Membrane in Escherichia coli*

PubMed Central

Urfer, Matthias; Bogdanovic, Jasmina; Lo Monte, Fabio; Moehle, Kerstin; Zerbe, Katja; Omasits, Ulrich; Ahrens, Christian H.; Pessi, Gabriella; Eberl, Leo; Robinson, John A.

2016-01-01

Increasing antibacterial resistance presents a major challenge in antibiotic discovery. One attractive target in Gram-negative bacteria is the unique asymmetric outer membrane (OM), which acts as a permeability barrier that protects the cell from external stresses, such as the presence of antibiotics. We describe a novel β-hairpin macrocyclic peptide JB-95 with potent antimicrobial activity against Escherichia coli. This peptide exhibits no cellular lytic activity, but electron microscopy and fluorescence studies reveal an ability to selectively disrupt the OM but not the inner membrane of E. coli. The selective targeting of the OM probably occurs through interactions of JB-95 with selected β-barrel OM proteins, including BamA and LptD as shown by photolabeling experiments. Membrane proteomic studies reveal rapid depletion of many β-barrel OM proteins from JB-95-treated E. coli, consistent with induction of a membrane stress response and/or direct inhibition of the Bam folding machine. The results suggest that lethal disruption of the OM by JB-95 occurs through a novel mechanism of action at key interaction sites within clusters of β-barrel proteins in the OM. These findings open new avenues for developing antibiotics that specifically target β-barrel proteins and the integrity of the Gram-negative OM. PMID:26627837

A sampler for coring sediments in rivers and estuaries

USGS Publications Warehouse

Prych, Edmund A.; Hubbell, D.W.

1966-01-01

A portable sampler developed to core submerged unconsolidated sediments collects cores that are 180 cm long and 4.75cm in diameter. The sampler is used from a 12-m boat in water depths up to 20 m and in flow velocities up to 1.5m per second to sample river and estuarine deposits ranging from silty clay to medium sand. Even in sand that cannot be penetrated with conventional corers, the sampler achieves easy penetration through the combined application of vibration, suction, and axial force. A piston in the core barrel creates suction, and the suspension system is arranged so that tension on the support cable produces both a downward force on the core barrel and a lateral support against overturning. Samples are usually retained because of slight compaction in the driving head; as a precaution, however, the bottom of the core barrel is covered by a plate that closes after the barrel is withdrawn from the bed. Tests show that sample-retainers placed within the driving head restrict penetration and limit core lengths. Stratification within cores is disrupted little as a result of the sampling process.

Temporal Progression of Visual Injury from Blast Exposure

DTIC Science & Technology

2013-09-01

included the design and construction of a silencer and dump tank. The final design is shown in Figure 8. A steel barrel lined with 2” of acoustic foam...was selected as the dump tank. It surrounds a rubber barrel lined with foam composite. The steel barrel is allowed to recoil on a cart, absorbing...test. Figure 8. (Left) Inner silencer assembly completed during Q4 of Year 1. (Right) Final silencer assembly with the outer steel drum

Fatigue Investigation of the E-2B/C Nose Landing Gear

DTIC Science & Technology

1975-12-31

Specimen - Outer Cylinder and Caster Barrel 9 3 E-2B NLG Test Specimen - Drag Brace 10 4 E-2B NLG Drag Brace Attachment Lugs Modification . . 11 5...Attachment Lug Fracture Surface . . 23 ■■■■ ? 16 Tow Link Modification 30 17 Tow Link #2 Failur 31 18 Tow Link #2 Fracture Face 32 19...34-" ’’- .-.„.,.,„...^ ,.., M1| lf^^~i*>-^^-^^ "u- II li ’ 7«™.™»«*" ■ NADC-75369-30 Bach «hock «true assembly consist« of the «xle- caster barrel, outer cylinder

Hartwell Lake Project, Savannah River, Georgia and South Carolina. Rehabilitation of Clemson Upper Diversion Dam. Construction Foundation Report. Volume 2. Appendices B thru E

DTIC Science & Technology

1989-08-01

remove by gravity -washed out 585.8 i -- 89. 2 gneiss from inner - ibarrel Bottom of hole 89.2’ Tape depth 89.0’ 90 -0 I-Note: 6-7-84 water level after...barrel and5 _-_89.3 washed all meterial Bottom of hole 89.3’ left in outer barrel- 90 out of barrel befor- drilling for pull I Tape depth 89.0’ Note

A Numerical Study on the Effect of Facesheet-Core Disbonds on the Buckling Load of Curved Honeycomb Sandwich Panels

NASA Technical Reports Server (NTRS)

Pineda, Evan J.; Myers, David E.; Bednarcyk, Brett A.; Krivanek, Thomas M.

2015-01-01

A numerical study on the effect of facesheet-core disbonds on the post-buckling response of curved honeycomb sandwich panels is presented herein. This work was conducted as part of the development of a damage tolerance approach for the next-generation Space Launch System heavy lift vehicle payload fairing. As such, the study utilized full-scale fairing barrel segments as the structure of interest. The panels were composed of carbon fiber reinforced polymer facesheets and aluminum honeycomb core. The panels were analyzed numerically using the finite element method. Facesheet and core nodes in a predetermined circular region were detached to simulate a disbond induced via low-speed impact between the outer mold line facesheet and honeycomb core. Surface-to-surface contact in the disbonded region was invoked to prevent interpenetration of the facesheet and core elements. The diameter of this disbonded region was varied and the effect of the size of the disbond on the post-buckling response was observed. A significant change in the slope of the edge load-deflection response was used to determine the onset of global buckling and corresponding buckling load.

Chloroplast outer envelope protein P39 in Arabidopsis thaliana belongs to the Omp85 protein family.

PubMed

Hsueh, Yi-Ching; Flinner, Nadine; Gross, Lucia E; Haarmann, Raimund; Mirus, Oliver; Sommer, Maik S; Schleiff, Enrico

2017-08-01

Proteins of the Omp85 family chaperone the membrane insertion of β-barrel-shaped outer membrane proteins in bacteria, mitochondria, and probably chloroplasts and facilitate the transfer of nuclear-encoded cytosolically synthesized preproteins across the outer envelope of chloroplasts. This protein family is characterized by N-terminal polypeptide transport-associated (POTRA) domains and a C-terminal membrane-embedded β-barrel. We have investigated a recently identified Omp85 family member of Arabidopsis thaliana annotated as P39. We show by in vitro and in vivo experiments that P39 is localized in chloroplasts. The electrophysiological properties of P39 are consistent with those of other Omp85 family members confirming the sequence based assignment of P39 to this family. Bioinformatic analysis showed that P39 lacks any POTRA domain, while a complete 16 stranded β-barrel including the highly conserved L6 loop is proposed. The electrophysiological properties are most comparable to Toc75-V, which is consistent with the phylogenetic clustering of P39 in the Toc75-V rather than the Toc75-III branch of the Omp85 family tree. Taken together P39 forms a pore with Omp85 family protein characteristics. The bioinformatic comparison of the pore region of Toc75-III, Toc75-V, and P39 shows distinctions of the barrel region most likely related to function. Proteins 2017; 85:1391-1401. © 2014 Wiley Periodicals, Inc. © 2014 Wiley Periodicals, Inc.

Experimental evidence that stripes do not cool zebras.

PubMed

Horváth, Gábor; Pereszlényi, Ádám; Száz, Dénes; Barta, András; Jánosi, Imre M; Gerics, Balázs; Åkesson, Susanne

2018-06-19

There are as many as 18 theories for the possible functions of the stripes of zebras, one of which is to cool the animal. We performed field experiments and thermographic measurements to investigate whether thermoregulation might work for zebra-striped bodies. A zebra body was modelled by water-filled metal barrels covered with horse, cattle and zebra hides and with various black, white, grey and striped patterns. The barrels were installed in the open air for four months while their core temperature was measured continuously. Using thermography, the temperature distributions of the barrel surfaces were compared to those of living zebras. The sunlit zebra-striped barrels reproduced well the surface temperature characteristics of sunlit zebras. We found that there were no significant core temperature differences between the striped and grey barrels, even on many hot days, independent of the air temperature and wind speed. The average core temperature of the barrels increased as follows: white cattle, grey cattle, real zebra, artificial zebra, grey horse, black cattle. Consequently, we demonstrate that zebra-striped coats do not keep the body cooler than grey coats challenging the hypothesis of a thermoregulatory role of zebra stripes.

Logging-while-coring method and apparatus

DOEpatents

Goldberg, David S.; Myers, Gregory J.

2007-11-13

A method and apparatus for downhole coring while receiving logging-while-drilling tool data. The apparatus includes core collar and a retrievable core barrel. The retrievable core barrel receives core from a borehole which is sent to the surface for analysis via wireline and latching tool The core collar includes logging-while-drilling tools for the simultaneous measurement of formation properties during the core excavation process. Examples of logging-while-drilling tools include nuclear sensors, resistivity sensors, gamma ray sensors, and bit resistivity sensors. The disclosed method allows for precise core-log depth calibration and core orientation within a single borehole, and without at pipe trip, providing both time saving and unique scientific advantages.

Logging-while-coring method and apparatus

DOEpatents

Goldberg, David S.; Myers, Gregory J.

2007-01-30

A method and apparatus for downhole coring while receiving logging-while-drilling tool data. The apparatus includes core collar and a retrievable core barrel. The retrievable core barrel receives core from a borehole which is sent to the surface for analysis via wireline and latching tool The core collar includes logging-while-drilling tools for the simultaneous measurement of formation properties during the core excavation process. Examples of logging-while-drilling tools include nuclear sensors, resistivity sensors, gamma ray sensors, and bit resistivity sensors. The disclosed method allows for precise core-log depth calibration and core orientation within a single borehole, and without at pipe trip, providing both time saving and unique scientific advantages.

Distinct Structural Elements Govern the Folding, Stability, and Catalysis in the Outer Membrane Enzyme PagP.

PubMed

Iyer, Bharat Ramasubramanian; Mahalakshmi, Radhakrishnan

2016-09-06

The outer membrane enzyme PagP is indispensable for lipid A palmitoylation in Gram-negative bacteria and has been implicated in resistance to host immune defenses. PagP possesses an unusual structure for an integral membrane protein, with a highly dynamic barrel domain that is tilted with respect to the membrane normal. In addition, it contains an N-terminal amphipathic helix. Recent functional and structural studies have shown that these molecular factors are critical for PagP to carry out its function in the challenging environment of the bacterial outer membrane. However, the precise contributions of the N-helix to folding and stability and residues that can influence catalytic rates remain to be addressed. Here, we identify a sequence-dependent stabilizing role for the N-terminal helix of PagP in the measured thermodynamic stability of the barrel. Using chimeric barrel sequences, we show that the Escherichia coli PagP N-terminal helix confers 2-fold greater stability to the Salmonella typhimurium barrel. Further, we find that the W78F substitution in S. typhimurium causes a nearly 20-fold increase in the specific activity in vitro for the phospholipase reaction, compared to that of E. coli PagP. Here, phenylalanine serves as a key regulator of catalysis, possibly by increasing the reaction rate. Through coevolution analysis, we detect an interaction network between seemingly unrelated segments of this membrane protein. Exchanging the structural and functional features between homologous PagP enzymes from E. coli and S. typhimurium has provided us with an understanding of the molecular factors governing PagP stability and function.

A sample-freezing drive shoe for a wire line piston core sampler

USGS Publications Warehouse

Murphy, F.; Herkelrath, W.N.

1996-01-01

Loss of fluids and samples during retrieval of cores of saturated, noncohesive sediments results in incorrect measures of fluid distributions and an inaccurate measure of the stratigraphic position of the sample. To reduce these errors, we developed a hollow drive shoe that freezes in place the lowest 3 inches (75 mm) of a 1.88-inch-diameter (48 mm), 5-foot-long (1.5 m) sediment sample taken using a commercial wire line piston core sampler. The end of the core is frozen by piping liquid carbon dioxide at ambient temperature through a steel tube from a bottle at the land surface to the drive shoe where it evaporates and expands, cooling the interior surface of the shoe to about -109??F (-78??C). Freezing a core end takes about 10 minutes. The device was used to collect samples for a study of oil-water-air distributions, and for studies of water chemistry and microbial activity in unconsolidated sediments at the site of an oil spill near Bemidji, Minnesota. Before freezing was employed, samples of sandy sediments from near the water table sometimes flowed out of the core barrel as the sampler was withdrawn. Freezing the bottom of the core allowed for the retention of all material that entered the core barrel and lessened the redistribution of fluids within the core. The device is useful in the unsaturated and shallow saturated zones, but does not freeze cores well at depths greater than about 20 feet (6 m) below water, possibly because the feed tube plugs with dry ice with increased exhaust back-pressure, or because sediment enters the annulus between the core barrel and the core barrel liner and blocks the exhaust.

Post-Buckling Analysis of Curved Honeycomb Sandwich Panels Containing Interfacial Disbonds

NASA Technical Reports Server (NTRS)

Pineda, Evan J.; Bednarcyk, Brett A.; Krivanek, Thomas K.

2016-01-01

A numerical study on the effect of facesheet-core disbonds on the post-buckling response of curved honeycomb sandwich panels is presented herein. This work was conducted as part of the development of a damage tolerance plan for the next-generation Space Launch System heavy lift launch vehicle payload fairing. As such, the study utilized full-scale fairing barrel segments as the structure of interest. The panels were composed of carbon fiber reinforced polymer facesheets and aluminum honeycomb core. The panels were analyzed numerically using the finite element method incorporating geometric nonlinearity. In a predetermined circular region, facesheet and core nodes were detached to simulate a disbond, between the outer mold line facesheet and honeycomb core, induced via low-speed impact. Surface-to-surface contact in the disbonded region was invoked to prevent interpenetration of the facesheet and core elements and obtain realistic stresses in the core. The diameter of this disbonded region was varied and the effect of the size of the disbond on the post-buckling response was observed. Significant changes in the slope of the edge load-deflection response were used to determine the onset of global buckling and corresponding buckling load. Finally, several studies were conducted to determine the sensitivity of the numerical predictions to refinement in the finite element mesh.

Early stages in the biogenesis of eukaryotic β-barrel proteins.

PubMed

Jores, Tobias; Rapaport, Doron

2017-09-01

The endosymbiotic organelles mitochondria and chloroplasts harbour, similarly to their prokaryotic progenitors, β-barrel proteins in their outer membrane. These proteins are encoded on nuclear DNA, translated on cytosolic ribosomes and imported into their target organelles by a dedicated machinery. Recent studies have provided insights into the import into the organelles and the membrane insertion of these proteins. Although the cytosolic stages of their biogenesis are less well defined, it is speculated that upon their synthesis, chaperones prevent β-barrel proteins from aggregation and keep them in an import-competent conformation. In this Review, we summarize the current knowledge about the biogenesis of β-barrel proteins, focusing on the early stages from the translation on cytosolic ribosomes to the recognition on the surface of the organelle. © 2017 Federation of European Biochemical Societies.

The Borrelia afzelii outer membrane protein BAPKO_0422 binds human factor-H and is predicted to form a membrane-spanning β-barrel

PubMed Central

Dyer, Adam; Brown, Gemma; Stejskal, Lenka; Laity, Peter R.; Bingham, Richard J.

2015-01-01

The deep evolutionary history of the Spirochetes places their branch point early in the evolution of the diderms, before the divergence of the present day Proteobacteria. As a spirochete, the morphology of the Borrelia cell envelope shares characteristics of both Gram-positive and Gram-negative bacteria. A thin layer of peptidoglycan, tightly associated with the cytoplasmic membrane, is surrounded by a more labile outer membrane (OM). This OM is rich in lipoproteins but with few known integral membrane proteins. The outer membrane protein A (OmpA) domain is an eight-stranded membrane-spanning β-barrel, highly conserved among the Proteobacteria but so far unknown in the Spirochetes. In the present work, we describe the identification of four novel OmpA-like β-barrels from Borrelia afzelii, the most common cause of erythema migrans (EM) rash in Europe. Structural characterization of one these proteins (BAPKO_0422) by SAXS and CD indicate a compact globular structure rich in β-strand consistent with a monomeric β-barrel. Ab initio molecular envelopes calculated from the scattering profile are consistent with homology models and demonstrate that BAPKO_0422 adopts a peanut shape with dimensions 25×45 Å (1 Å=0.1 nm). Deviations from the standard C-terminal signature sequence are apparent; in particular the C-terminal phenylalanine residue commonly found in Proteobacterial OM proteins is replaced by isoleucine/leucine or asparagine. BAPKO_0422 is demonstrated to bind human factor H (fH) and therefore may contribute to immune evasion by inhibition of the complement response. Encoded by chromosomal genes, these proteins are highly conserved between Borrelia subspecies and may be of diagnostic or therapeutic value. PMID:26181365

Structure and function of POTRA domains of Omp85/TPS superfamily.

PubMed

Simmerman, Richard F; Dave, Ashita M; Bruce, Barry D

2014-01-01

The Omp85/TPS (outer-membrane protein of 85 kDa/two-partner secretion) superfamily is a ubiquitous and major class of β-barrel proteins. This superfamily is restricted to the outer membranes of gram-negative bacteria, mitochondria, and chloroplasts. The common architecture, with an N-terminus consisting of repeats of soluble polypeptide-transport-associated (POTRA) domains and a C-terminal β-barrel pore is highly conserved. The structures of multiple POTRA domains and one full-length TPS protein have been solved, yet discovering roles of individual POTRA domains has been difficult. This review focuses on similarities and differences between POTRA structures, emphasizing POTRA domains in autotrophic organisms including plants and cyanobacteria. Unique roles, specific for certain POTRA domains, are examined in the context of POTRA location with respect to their attachment to the β-barrel pore, and their degree of biological dispensability. Finally, because many POTRA domains may have the ability to interact with thousands of partner proteins, possible modes of these interactions are also explored. © 2014 Elsevier Inc. All rights reserved.

Alternative function for the mitochondrial SAM complex in biogenesis of alpha-helical TOM proteins.

PubMed

Stojanovski, Diana; Guiard, Bernard; Kozjak-Pavlovic, Vera; Pfanner, Nikolaus; Meisinger, Chris

2007-12-03

The mitochondrial outer membrane contains two preprotein translocases: the general translocase of outer membrane (TOM) and the beta-barrel-specific sorting and assembly machinery (SAM). TOM functions as the central entry gate for nuclear-encoded proteins. The channel-forming Tom40 is a beta-barrel protein, whereas all Tom receptors and small Tom proteins are membrane anchored by a transmembrane alpha-helical segment in their N- or C-terminal portion. Synthesis of Tom precursors takes place in the cytosol, and their import occurs via preexisting TOM complexes. The precursor of Tom40 is then transferred to SAM for membrane insertion and assembly. Unexpectedly, we find that the biogenesis of alpha-helical Tom proteins with a membrane anchor in the C-terminal portion is SAM dependent. Each SAM protein is necessary for efficient membrane integration of the receptor Tom22, whereas assembly of the small Tom proteins depends on Sam37. Thus, the substrate specificity of SAM is not restricted to beta-barrel proteins but also includes the majority of alpha-helical Tom proteins.

Electrostatic networks control plug stabilization in the PapC usher.

PubMed

Pham, Thieng; Henderson, Nadine S; Werneburg, Glenn T; Thanassi, David G; Delcour, Anne H

2015-01-01

The PapC usher, a β-barrel pore in the outer membrane of uropathogenic Escherichia coli, is used for assembly of the P pilus, a key virulence factor in bacterial colonization of human kidney cells. Each PapC protein is composed of a 24-stranded β-barrel channel, flanked by N- and C-terminal globular domains protruding into the periplasm, and occluded by a plug domain (PD). The PD is displaced from the channel towards the periplasm during pilus biogenesis, but the molecular mechanism for PD displacement remains unclear. Two structural features within the β-barrel, an α-helix and β5-6 hairpin loop, may play roles in controlling plug stabilization. Here we have tested clusters of residues at the interface of the plug, barrel, α-helix and hairpin, which participate in electrostatic networks. To assess the roles of these residues in plug stabilization, we used patch-clamp electrophysiology to compare the activity of wild-type and mutant PapC channels containing alanine substitutions at these sites. Mutations interrupting each of two salt bridge networks were relatively ineffective in disrupting plug stabilization. However, mutation of two pairs of arginines located at the inner and the outer surfaces of the PD resulted in an enhanced propensity for plug displacement. One arginine pair involved in a repulsive interaction between the linkers that tether the plug to the β-barrel was particularly sensitive to mutation. These results suggest that plug displacement, which is necessary for pilus assembly and translocation, may require a weakening of key electrostatic interactions between the plug linkers, and the plug and the α-helix.

Final Report of the Rifling Profile Push Test

DTIC Science & Technology

2007-06-01

barrel lands through the copper alloy jacket, as shown in figure 6. As a result, compression of the jacket material above the steel core will occur...resistance pressure of the M855 projectile in an M16A2 barrel section. The M855 test projectiles were tested in a 2 × 2 matrix, two different M16A2 barrel ...1 Figure 2. M16A2 barrel machined section. The units of measure are in cm.................................2 Figure 3

46th Annual Gun and Missile Systems Conference and Exhibition

DTIC Science & Technology

2011-09-01

Grade Sensors Through Use of Accelerated Aging Principles Mr. Scott Gift 11657 Modeling of the Autofrettage Processes of a Gun Barrel Mr. Sudhir...Emissions Measured on the Outer Portion of a Composite Barrel Ms. Rushie Ghimire GUN & MISSILE SYSTEMS ADDITIONAL AUTHORS GUN & MISSILE SYSTEMS...X 3BCT 2BCT X 1BCT TACP COLT • BLUFOR scout squad engaged by enemy infantry and are overwhelmed by heavy machine gun fire 100m to their northwest

Gunshot residue patterns on skin in angled contact and near contact gunshot wounds.

PubMed

Plattner, T; Kneubuehl, B; Thali, M; Zollinger, U

2003-12-17

The goal of this study was the reproduction of shape and pattern of gunshot residues in near contact and contact gunshot wounds by a series of experimental gunshots on a skin and soft tissue model. The aim was to investigate the shape and direction of soot deposits with regard to the muzzle according to different muzzle-target angles, firing distances, type of ammunition and weapon and barrel length. Based on a review of the literature and on the results of the experiments the authors could make the following statements of gunshot residues in angled contact and close contact gunshot: (1) gunshot residues on the target surface can be differentiated in a "inner" and "outer powder soot zone"; (2) the outer powder soot zone is much less visible than the inner powder soot zone and may lack on human skin; (3) with increasing muzzle target distance both inner and outer powder soot halo increase in size and decrease in density; (4) in angled shots the inner powder soot halo shows an eccentric, elliptic shape which points towards the muzzle, regardless of ammunition, calibre and barrel length; (5) the outer powder soot points away from the muzzle in angled contact and close contact shots.

An improved method for field extraction and laboratory analysis of large, intact soil cores

USGS Publications Warehouse

Tindall, J.A.; Hemmen, K.; Dowd, J.F.

1992-01-01

Various methods have been proposed for the extraction of large, undisturbed soil cores and for subsequent analysis of fluid movement within the cores. The major problems associated with these methods are expense, cumbersome field extraction, and inadequate simulation of unsaturated flow conditions. A field and laboratory procedure is presented that is economical, convenient, and simulates unsaturated and saturated flow without interface flow problems and can be used on a variety of soil types. In the field, a stainless steel core barrel is hydraulically pressed into the soil (30-cm diam. and 38 cm high), the barrel and core are extracted from the soil, and after the barrel is removed from the core, the core is then wrapped securely with flexible sheet metal and a stainless mesh screen is attached to the bottom of the core for support. In the laboratory the soil core is set atop a porous ceramic plate over which a soil-diatomaceous earth slurry has been poured to assure good contact between plate and core. A cardboard cylinder (mold) is fastened around the core and the empty space filled with paraffin wax. Soil cores were tested under saturated and unsaturated conditions using a hanging water column for potentials ???0. Breakthrough curves indicated that no interface flow occurred along the edge of the core. This procedure proved to be reliable for field extraction of large, intact soil cores and for laboratory analysis of solute transport.

Structural Basis for Translocation of a Biofilm-supporting Exopolysaccharide across the Bacterial Outer Membrane.

PubMed

Wang, Yan; Andole Pannuri, Archana; Ni, Dongchun; Zhou, Haizhen; Cao, Xiou; Lu, Xiaomei; Romeo, Tony; Huang, Yihua

2016-05-06

The partially de-N-acetylated poly-β-1,6-N-acetyl-d-glucosamine (dPNAG) polymer serves as an intercellular biofilm adhesin that plays an essential role for the development and maintenance of integrity of biofilms of diverse bacterial species. Translocation of dPNAG across the bacterial outer membrane is mediated by a tetratricopeptide repeat-containing outer membrane protein, PgaA. To understand the molecular basis of dPNAG translocation, we determined the crystal structure of the C-terminal transmembrane domain of PgaA (residues 513-807). The structure reveals that PgaA forms a 16-strand transmembrane β-barrel, closed by four loops on the extracellular surface. Half of the interior surface of the barrel that lies parallel to the translocation pathway is electronegative, suggesting that the corresponding negatively charged residues may assist the secretion of the positively charged dPNAG polymer. In vivo complementation assays in a pgaA deletion bacterial strain showed that a cluster of negatively charged residues proximal to the periplasm is necessary for biofilm formation. Biochemical analyses further revealed that the tetratricopeptide repeat domain of PgaA binds directly to the N-deacetylase PgaB and is critical for biofilm formation. Our studies support a model in which the positively charged PgaB-bound dPNAG polymer is delivered to PgaA through the PgaA-PgaB interaction and is further targeted to the β-barrel lumen of PgaA potentially via a charge complementarity mechanism, thus priming the translocation of dPNAG across the bacterial outer membrane. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Composite drill pipe and method for forming same

DOEpatents

Leslie, James C; Leslie, II, James C; Heard, James; Truong, Liem; Josephson, Marvin

2014-04-15

Metal inner and outer fittings configured, the inner fitting configured proximally with an external flange and projecting distally to form a cylindrical barrel and stepped down-in-diameter to form an abutment shoulder and then projecting further distally to form a radially inwardly angled and distally extending tapered inner sleeve. An outer sleeve defining a torque tube is configured with a cylindrical collar to fit over the barrel and is formed to be stepped up in diameter in alignment with the first abutment shoulder to then project distally forming a radially outwardly tapered and distally extending bonding surface to cooperate with the inner sleeve to cooperate with the inner sleeve in forming a annular diverging bonding cavity to receive the extremity of a composite pipe to abut against the abutment shoulders and to be bonded to the respective bonding surfaces by a bond.

Phylogenetic Analysis of Mitochondrial Outer Membrane β-Barrel Channels

PubMed Central

Wojtkowska, Małgorzata; Jąkalski, Marcin; Pieńkowska, Joanna R.; Stobienia, Olgierd; Karachitos, Andonis; Przytycka, Teresa M.; Weiner, January; Kmita, Hanna; Makałowski, Wojciech

2012-01-01

Transport of molecules across mitochondrial outer membrane is pivotal for a proper function of mitochondria. The transport pathways across the membrane are formed by ion channels that participate in metabolite exchange between mitochondria and cytoplasm (voltage-dependent anion-selective channel, VDAC) as well as in import of proteins encoded by nuclear genes (Tom40 and Sam50/Tob55). VDAC, Tom40, and Sam50/Tob55 are present in all eukaryotic organisms, encoded in the nuclear genome, and have β-barrel topology. We have compiled data sets of these protein sequences and studied their phylogenetic relationships with a special focus on the position of Amoebozoa. Additionally, we identified these protein-coding genes in Acanthamoeba castellanii and Dictyostelium discoideum to complement our data set and verify the phylogenetic position of these model organisms. Our analysis show that mitochondrial β-barrel channels from Archaeplastida (plants) and Opisthokonta (animals and fungi) experienced many duplication events that resulted in multiple paralogous isoforms and form well-defined monophyletic clades that match the current model of eukaryotic evolution. However, in representatives of Amoebozoa, Chromalveolata, and Excavata (former Protista), they do not form clearly distinguishable clades, although they locate basally to the plant and algae branches. In most cases, they do not posses paralogs and their sequences appear to have evolved quickly or degenerated. Consequently, the obtained phylogenies of mitochondrial outer membrane β-channels do not entirely reflect the recent eukaryotic classification system involving the six supergroups: Chromalveolata, Excavata, Archaeplastida, Rhizaria, Amoebozoa, and Opisthokonta. PMID:22155732

Outer Membrane Protein Folding and Topology from a Computational Transfer Free Energy Scale.

PubMed

Lin, Meishan; Gessmann, Dennis; Naveed, Hammad; Liang, Jie

2016-03-02

Knowledge of the transfer free energy of amino acids from aqueous solution to a lipid bilayer is essential for understanding membrane protein folding and for predicting membrane protein structure. Here we report a computational approach that can calculate the folding free energy of the transmembrane region of outer membrane β-barrel proteins (OMPs) by combining an empirical energy function with a reduced discrete state space model. We quantitatively analyzed the transfer free energies of 20 amino acid residues at the center of the lipid bilayer of OmpLA. Our results are in excellent agreement with the experimentally derived hydrophobicity scales. We further exhaustively calculated the transfer free energies of 20 amino acids at all positions in the TM region of OmpLA. We found that the asymmetry of the Gram-negative bacterial outer membrane as well as the TM residues of an OMP determine its functional fold in vivo. Our results suggest that the folding process of an OMP is driven by the lipid-facing residues in its hydrophobic core, and its NC-IN topology is determined by the differential stabilities of OMPs in the asymmetrical outer membrane. The folding free energy is further reduced by lipid A and assisted by general depth-dependent cooperativities that exist between polar and ionizable residues. Moreover, context-dependency of transfer free energies at specific positions in OmpLA predict regions important for protein function as well as structural anomalies. Our computational approach is fast, efficient and applicable to any OMP.

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

Crawford, E.

Higher wellhead prices are not expected to bring on a significant increase in supplies of oil and natural gas from new outer continental shelf (OCS) reservoirs between now and 1982. Between 1982 and 1987, however, the situation should change: if 1987 prices range from $7.50 to $25 per barrel, supplies are expected to increase from two to 3.5 million barrels per day, respectively. These results from an Arthur D. Little Co. study are based on the assumption of continued OCS leasing and development, although uncertainties remain about the extent of recoverable reserves. For example, no indications of commercial hydrocarbons havemore » been found in the Gulf of Alaska for the three wells dug so far. In general a price of $20 per barrel is needed to make the risky exploration worthwhile for oil companies. (DCK)« less

An oilspill risk analysis for the Gulf of Mexico outer continental shelf lease area; regional environmental impact statement

USGS Publications Warehouse

LaBelle, R.P.

1982-01-01

An oilspill risk analysis was conducted for the Gulf of Mexico Outer Continental Shelf (OCS)lease area region. Results of the analysis can be used to determine relative risks associated with oil production in different regions to be offered in OCS Lease Sales 72, 74, and 79. The analysis considered the probability of spill occurrences based on historical trends; likely movement of oil slicks based on a climatological model; and locations of major environmental resources which could be vulnerable to spilled oil. The times between spill occurrence and contact with resources were estimated to aid in estimating slick characteristics. Critical assumptions made for this particular analysis were (1) that oil exists in the lease area, and (2) that oil will be, found and produced from tracts sold in sales 72, 74, and 79. On the basis of a most likely resource estimate of 241 million barrels of oil to be produced over an 18-year production life from sales to be held in 1983 (sales 72, 74, 79), it was calculated that approximately one oilspill of 1,000 barrels or larger will occur. The estimated probability that one or more oilspills of 1,000 barrels or larger will occur and contact land after being at sea less than 30 days is 41-percent. For a high resource estimate case of sales to be held in 1983, 717 million barrels are estimated to be produced over an 18-year production life with an 83-percent chance of one or more spills of 1,000 barrels or larger occurring and contacting land within 30 days. These results depend upon the routes and methods chosen to transport oil from OCS platforms to shore. Given a total development scenario in which 5.6 billion barrels of oil are estimated to be present and produced, it was calculated that 18 oilspills of 1,000 barrels or larger will occur over the 40-year production life of the proposed lease area. The estimated probability that one or more oilspills of 1,000 barrels or larger will occur and contact land after being at sea less than 30 days is greater than 99.5 percent for this scenario. These probabilities also reflect the assumptions that oilspills remain intact for up to 30 days, do not weather, and are not cleaned up. It should be noted that the expected number of spills from the total development scenario is less than one-half that of the expected number from existing tanker transportation of crude oil imports in the Gulf area.

Normal Mode Derived Models of the Physical Properties of Earth's Outer Core

NASA Astrophysics Data System (ADS)

Irving, J. C. E.; Cottaar, S.; Lekic, V.; Wu, W.

2017-12-01

Earth's outer core, the largest reservoir of metal in our planet, is comprised of an iron alloy of an uncertain composition. Its dynamical behaviour is responsible for the generation of Earth's magnetic field, with convection driven both by thermal and chemical buoyancy fluxes. Existing models of the seismic velocity and density of the outer core exhibit some variation, and there are only a small number of models which aim to represent the outer core's density.It is therefore important that we develop a better understanding of the physical properties of the outer core. Though most of the outer core is likely to be well mixed, it is possible that the uppermost outer core is stably stratified: it may be enriched in light elements released during the growth of the solid, iron enriched, inner core; by elements dissolved from the mantle into the outer core; or by exsolution of compounds previously dissolved in the liquid metal which will eventually be swept into the mantle. The stratified layer may host MAC or Rossby waves and it could impede communication between the chemically differentiated mantle and outer core, including screening out some of the geodynamo's signal. We use normal mode center frequencies to estimate the physical properties of the outer core in a Bayesian framework. We estimate the mineral physical parameters needed to best produce velocity and density models of the outer core which are consistent with the normal mode observations. We require that our models satisfy realistic physical constraints. We create models of the outer core with and without a distinct uppermost layer and assess the importance of this region.Our normal mode-derived models are compared with observations of body waves which travel through the outer core. In particular, we consider SmKS waves which are especially sensitive to the uppermost outer core and are therefore an important way to understand the robustness of our models.

The TonB-dependent Transporter FhuA in Planar Lipid Bilayers: partial exit of its plug from the barrel

PubMed Central

Udho, Eshwar; Jakes, Karen S.; Finkelstein, Alan

2012-01-01

TonB-dependent transporters (TBDTs), which transport iron-chelating siderophores and vitamin B12 across the outer membrane of gram negative bacteria, share a conserved architecture of a 22-stranded beta-barrel with an amino-terminal plug domain occluding the barrel. We previously reported that we could induce TBDTs to reversibly open in planar lipid bilayers via the use of urea and that these channels were responsive to physiological concentrations of ligands. Here we report that in the presence of urea, trypsin can cleave the amino-terminal 67 residues of the plug of the TonB-dependent transporter FhuA, as assessed by gel shift and mass spectrometry assays. On the bilayer, trypsin treatment in the presence of urea resulted in the induced conductance no longer being reversed upon removal of urea, suggesting that urea opens intact FhuA channels by pulling the plug at least partly out of the barrel, and that removal of the urea then allows reinsertion of the plug into the barrel. When expressed separately, the FhuA plug domain was found to be a mostly unfolded structure that was able to occlude isolated FhuA beta-barrels inserted into the membrane. Thus, although folded in the barrel, the plug need not be folded upon exiting the barrel. The rate of insertion of the beta-barrels into the membrane was tremendously increased in the presence of an osmotic gradient provided by either urea or glycerol. Negative staining electron microscopy showed that FhuA in a detergent solution formed vesicles, thus explaining why an osmotic gradient promoted the insertion of FhuA into membranes. PMID:22846061

High performance railgun barrels for laboratory use

NASA Astrophysics Data System (ADS)

Bauer, David P.; Newman, Duane C.

1993-01-01

High performance low-cost, laboratory railgun barrels are now available, comprised of an inherently stiff containment structure which surrounds the bore components machined from 'off the-shelf' materials. The shape of the containment structure was selected to make the barrel inherently stiff. The structure consists of stainless steel laminations which do not compromise the electrical efficiency of the railgun. The modular design enhances the utility of the barrel, as it is easy to service between shots, and can be 're-cored' to produce different configurations and sizes using the same structure. We have produced barrels ranging from 15 mm to 90 mm square bore, a 30 mm round bore, and in lengths varying from 0.25 meters to 10 meters long. Successful tests with both plasma and solid metal armatures have demonstrated the versatility and performance of this design.

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

PubMed Central

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

2001-01-01

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

An oilspill risk analysis for the Mid-Atlantic (proposed sale 76) outer continental shelf lease area

USGS Publications Warehouse

Samuels, W.B.; Hopkins, Dorothy

1982-01-01

An oilspill risk analysis was conducted for the mid-Atlantic (proposed sale 76) Outer Continental Shelf (OCS) lease area. The analysis considered: the probability of spill occurrences based on historical trends; likely movement of oil slicks based on a climatological model; and locations of environmental resources which could be vulnerable to spilled oil. The times between spill occurrence and contact with resources were estimated to aid analysts in estimating slick characteristics. Critical assumptions made for this particular analysis were (1) that oil exists in the lease area, and (2) that 0.879 billion barrels of oil will be found and produced from tracts sold in sale 76. On the basis of this resource estimate, it was calculated that 3 to 4 oilspills of 1,000 barrels or greater will occur over the 30-year production life of the proposed sale 76 lease tracts. The results also depend upon the routes and methods chosen to transport oil from 0CS platforms to shore. Given the above assumptions, the estimated probability that one or more oilspills of 1,000 barrels or larger will occur and contact land after being at sea less than 30 days is 0.36; for spills 10,000 barrels or larger, the probability is 0.22. These probabilities also reflect the following assumptions: oilspills remain intact for up to 30 days, do not weather, and are not cleaned up. It is noteworthy that over 90 percent of the risk from proposed sale 76 is due to transportation rather than production of oil. In addition, the risks from proposed sale 76 are about 1/10 to 1/15 those of existing tanker transportation of crude oil imports and refined products in the mid-Atlantic area.

Ice Core Records of Recent Northwest Greenland Climate

NASA Astrophysics Data System (ADS)

Osterberg, E. C.; Wong, G. J.; Ferris, D.; Lutz, E.; Howley, J. A.; Kelly, M. A.; Axford, Y.; Hawley, R. L.

2014-12-01

Meteorological station data from NW Greenland indicate a 3oC temperature rise since 1990, with most of the warming occurring in fall and winter. According to remote sensing data, the NW Greenland ice sheet (GIS) and coastal ice caps are responding with ice mass loss and margin retreat, but the cryosphere's response to previous climate variability is poorly constrained in this region. We are developing multi-proxy records (lake sediment cores, ice cores, glacial geologic data, glaciological models) of Holocene climate change and cryospheric response in NW Greenland to improve projections of future ice loss and sea level rise in a warming climate. As part of our efforts to develop a millennial-length ice core paleoclimate record from the Thule region, we collected and analyzed snow pit samples and short firn cores (up to 21 m) from the coastal region of the GIS (2Barrel site; 76.9317o N, 63.1467o W, 1685 m el.) and the summit of North Ice Cap (76.938o N, 67.671o W, 1273 m el.) in 2011, 2012 and 2014. The 2Barrel ice core record has statistically significant relationships with regional spring and fall Baffin Bay sea ice extent, summertime temperature, and annual precipitation. Here we evaluate relationships between the 2014 North Ice Cap firn core glaciochemical record and climate variability from regional instrumental stations and reanalysis datasets. We compare the coastal North Ice Cap record to more inland records from 2Barrel, Camp Century and NEEM to evaluate spatial and elevational gradients in recent NW Greenland climate change.

Earth's Outer Core Properties Estimated Using Bayesian Inversion of Normal Mode Eigenfrequencies

NASA Astrophysics Data System (ADS)

Irving, J. C. E.; Cottaar, S.; Lekic, V.

2016-12-01

The outer core is arguably Earth's most dynamic region, and consists of an iron-nickel liquid with an unknown combination of lighter alloying elements. Frequencies of Earth's normal modes provide the strongest constraints on the radial profiles of compressional wavespeed, VΦ, and density, ρ, in the outer core. Recent great earthquakes have yielded new normal mode measurements; however, mineral physics experiments and calculations are often compared to the Preliminary reference Earth model (PREM), which is 35 years old and does not provide uncertainties. Here we investigate the thermo-elastic properties of the outer core using Earth's free oscillations and a Bayesian framework. To estimate radial structure of the outer core and its uncertainties, we choose to exploit recent datasets of normal mode centre frequencies. Under the self-coupling approximation, centre frequencies are unaffected by lateral heterogeneities in the Earth, for example in the mantle. Normal modes are sensitive to both VΦ and ρ in the outer core, with each mode's specific sensitivity depending on its eigenfunctions. We include a priori bounds on outer core models that ensure compatibility with measurements of mass and moment of inertia. We use Bayesian Monte Carlo Markov Chain techniques to explore different choices in parameterizing the outer core, each of which represents different a priori constraints. We test how results vary (1) assuming a smooth polynomial parametrization, (2) allowing for structure close to the outer core's boundaries, (3) assuming an Equation-of-State and adiabaticity and inverting directly for thermo-elastic parameters. In the second approach we recognize that the outer core may have distinct regions close to the core-mantle and inner core boundaries and investigate models which parameterize the well mixed outer core separately from these two layers. In the last approach we seek to map the uncertainties directly into thermo-elastic parameters including the bulk modulus, its pressure derivative, and molar mass and volume, with particular attention paid to the (inherent) trade-offs between the different coefficients. We discuss our results in terms of added uncertainty to the light element composition of the outer core and the potential existence of anomalous structure near the outer core's boundaries.

CryoEM structures of membrane pore and prepore complex reveal cytolytic mechanism of Pneumolysin

PubMed Central

van Pee, Katharina; Neuhaus, Alexander; D'Imprima, Edoardo; Mills, Deryck J; Kühlbrandt, Werner; Yildiz, Özkan

2017-01-01

Many pathogenic bacteria produce pore-forming toxins to attack and kill human cells. We have determined the 4.5 Å structure of the ~2.2 MDa pore complex of pneumolysin, the main virulence factor of Streptococcus pneumoniae, by cryoEM. The pneumolysin pore is a 400 Å ring of 42 membrane-inserted monomers. Domain 3 of the soluble toxin refolds into two ~85 Å β-hairpins that traverse the lipid bilayer and assemble into a 168-strand β-barrel. The pore complex is stabilized by salt bridges between β-hairpins of adjacent subunits and an internal α-barrel. The apolar outer barrel surface with large sidechains is immersed in the lipid bilayer, while the inner barrel surface is highly charged. Comparison of the cryoEM pore complex to the prepore structure obtained by electron cryo-tomography and the x-ray structure of the soluble form reveals the detailed mechanisms by which the toxin monomers insert into the lipid bilayer to perforate the target membrane. DOI: http://dx.doi.org/10.7554/eLife.23644.001 PMID:28323617

Blank fire configuration for automatic pistol

DOEpatents

Teague, Tommy L.

1990-01-01

A pistol configured to fire blank cartridges includes a modified barrel with a breech portion connected to an aligned inner sleeve. Around the inner sleeve, there is disposed an outer sleeve having a vent therein through which the cartridge discharges. The breech portion is connected to a barrel anchor to move backward in a slight arc when the pistol is fired. A spring retention rod projects from the barrel anchor and receives a shortened recoil spring therearound which recoil spring has one end abutting a stop on the barrel anchor and the other end in abutment with the end of a spring retaining cup. The spring retaining cup is engaged by a flange projecting from a slide so that when the pistol is fired, the slide moves rearwardly against the compression of the spring to eject the spent cartridge and then moves forwardly under the urging of the spring to load a fresh cartridge into the breech portion. The spring then returns all of the slidable elements to their initial position so that the pistol may again be fired.

Calibration of the CMS hadron calorimeter in Run 2

NASA Astrophysics Data System (ADS)

Chadeeva, M.; Lychkovskaya, N.

2018-03-01

Various calibration techniques for the CMS Hadron calorimeter in Run 2 and the results of calibration using 2016 collision data are presented. The radiation damage corrections, intercalibration of different channels using the phi-symmetry technique for barrel, endcap and forward calorimeter regions are described, as well as the intercalibration with muons of the outer hadron calorimeter. The achieved intercalibration precision is within 3%. The in situ energy scale calibration is performed in the barrel and endcap regions using isolated charged hadrons and in the forward calorimeter using the Zarrow ee process. The impact of pileup and the developed technique of correction for pileup is also discussed. The achieved uncertainty of the response to hadrons is 3.4% in the barrel and 2.6% in the endcap region (at the pseudorapidity range |η|<2) and is dominated by the systematic uncertainty due to pileup contributions.

The bar PANDA Barrel-TOF Detector at FAIR

NASA Astrophysics Data System (ADS)

Zimmermann, S.; Suzuki, K.; Steinschaden, D.; Chirita, M.; Ahmed, G.; Dutta, K.; Kalita, K.; Lehmann, A.; Böhm, M.; Schwarz, K.; Orth, H.; Brinkmann, K.-Th.

2017-08-01

The barrel-Time-of-Flight subdetector is one of the outer layers of the multi-layer design of the \\panda target spectrometer. It is designed with a minimal material budget in mind mainly consisting of 90×30×5 mm3 thin plastic scintillator tiles read out on each end by a serial connection of 4 SiPMs. 120 such tiles are placed on 16 2460 × 180 mm2 PCB boards forming a barrel covering an azimuthal angle from 22.5o to 150o. The detector is designed to achieve a time resolution below σ< 100 ps which allows to distinguish events in the constant stream of hits, as well as particle identification below the Cherenkov threshold via the time-of-flight; simultaneously providing the interaction times of events. The current prototype achieved a time resolution of ~54 ps, well below the design goal.

Development and Assessment of a New CFRP Rod Anchor System for Prestressed Concrete

NASA Astrophysics Data System (ADS)

Al-Mayah, A.; Soudki, K.; Plumtree, A.

2006-09-01

Design concepts and experimental assessment of a new wedge anchor system for prestressing CFRP rods are presented. This compact and reusable anchor consists of an outer cylinder (barrel), a number of wedges, and a soft metal sleeve. The contacting surfaces of the wedges and barrel have a circular profile along the length of the anchor. Tensile testing using different presetting loads, geometric configurations, and rod sizes was carried out. The relationship of the tensile load and displacement of the rod was established. Presetting was found unnecessary since the anchor system was found to be capable of carrying the full design strength of the rods.

30 CFR 556.43 - Chargeability for production.

Code of Federal Regulations, 2012 CFR

2012-07-01

... LEASING OF SULPHUR OR OIL AND GAS IN THE OUTER CONTINENTAL SHELF Issuance of Leases § 556.43 Chargeability...-trust certificate, certificate of deposit for a security, fractional undivided interest in oil, gas, or... applicable prior production period: (1) The average daily production in barrels of crude oil, natural gas...

30 CFR 556.43 - Chargeability for production.

Code of Federal Regulations, 2014 CFR

2014-07-01

... LEASING OF SULPHUR OR OIL AND GAS IN THE OUTER CONTINENTAL SHELF Issuance of Leases § 556.43 Chargeability...-trust certificate, certificate of deposit for a security, fractional undivided interest in oil, gas, or... applicable prior production period: (1) The average daily production in barrels of crude oil, natural gas...

30 CFR 556.43 - Chargeability for production.

Code of Federal Regulations, 2013 CFR

2013-07-01

... LEASING OF SULPHUR OR OIL AND GAS IN THE OUTER CONTINENTAL SHELF Issuance of Leases § 556.43 Chargeability...-trust certificate, certificate of deposit for a security, fractional undivided interest in oil, gas, or... applicable prior production period: (1) The average daily production in barrels of crude oil, natural gas...

Vibracoring on the New Jersey Shelf: Investigating the Stratigraphic Response to 50,000 Years of Eustasy

DTIC Science & Technology

2007-01-01

accomplished during weather conditions that otherwise precluded operating the vibracorer. More than 100 gravity core casts were conducted. When...barrel, or shelly /sandy material caught in the core catcher. We bagged all samples we deemed significant enough to keep. All gravity core

Oil spills, 1971-75, Gulf of Mexico outer continental shelf

USGS Publications Warehouse

Danenberger, Elmer P.

1976-01-01

Oil spillage connected with federally supervised drilling and production activities has been a matter of wide public concern. In its supervision of mineral-resource development on the Outer Continental Shelf (OCS), the U.S. Geological Survey is responsible for the day-to-day inspection and monitoring of OCS oil and gas operations. During these activities, the U.S. Geological Survey records and investigates hydrocarbon discharges resulting from such operations. Beginning in 1971, all spills have been recorded, and a computer file has been maintained on all spills of 1 barrel or more. The total Gulf of Mexico OCS oil spillage recorded during January 1, 1971-December 31, 1975, amounted to 51,421 barrels. Production during that period amounted to 35,219 barrels per barrel spilled. In all, 5,857 spills were recorded, but 85.5 percent of the total spill volume was contributed by just 5 incidents. The environmental effect of these incidents apparently was minimal and of short duration. No spills of more than 50 barrels resulted from drilling operations during the period. The only spillage resulting from blowouts was caused by nondrilling incidents, including completion, production, and workover. The amount of oil discharged from spills of less than 50 barrels decreased by more than half between 1971 and 1975. The improvement reflects changes in the operating philosophy of the offshore industry, tightening of U.S. Geological Survey operating orders, and substantial increases in the inspection force. Most production-platform spills involve failures in the sump system, the separator system, or other hydrocarbon-handling equipment; improved sump-system designs and better high-low-level controls have reduced both the number and the volume of spills. Pipeline and pump spills also declined significantly, although the decline appears less attributable to revisions in OCS operating requirements. No operator consistently contributed a disproportionate amount of spillage. Most of the platforms having production spills had only one spill during the period. Of the 304 platforms having incidents, 255 had 2 spills or less and 188 had only 1 spill. Comparison of the volume spilled with the volume produced for Gulf of Mexico OCS operations during 1971-75 results in a spillage rate of 0.0028 percent. Spillage from tankers is estimated to be greater. The OCS drilling and production spillage rate is not expected to increase during exploration and development of the frontier areas.

Material with core-shell structure

DOEpatents

Luhrs, Claudia [Rio Rancho, NM; Richard, Monique N [Ann Arbor, MI; Dehne, Aaron [Maumee, OH; Phillips, Jonathan [Rio Rancho, NM; Stamm, Kimber L [Ann Arbor, MI; Fanson, Paul T [Brighton, MI

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.

Tryptophan 375 stabilizes the outer-domain core of gp120 for HIV vaccine immunogen design.

PubMed

Hu, Duoyi; Bowder, Dane; Wei, Wenzhong; Thompson, Jesse; Wilson, Mark A; Xiang, Shi-Hua

2017-05-25

The outer-domain core of gp120 may serve as a better HIV vaccine immunogen than the full-length gp120 because of its greater stability and immunogenicity. In our previous report, we introduced two disulfide bonds to the outer-domain core of gp120 to fix its conformation into a CD4-bound state, which resulted in a significant increase in its immunogenicity when compared to the wild-type outer-domain core. In this report, to further improve the immunogenicity of the outer-domain core based immunogen, we have introduced a Tryptophan residue at gp120 amino acid sequence position 375 (375S/W). Our data from immunized guinea pigs indeed shows a striking increase in the immune response due to this stabilized core outer-domain. Therefore, we conclude that the addition of 375W to the outer-domain core of gp120 further stabilizes the structure of immunogen and increases the immunogenicity. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Common Envelope Shaping of Planetary Nebulae

NASA Astrophysics Data System (ADS)

García-Segura, Guillermo; Ricker, Paul M.; Taam, Ronald E.

2018-06-01

The morphology of planetary nebulae emerging from the common envelope phase of binary star evolution is investigated. Using initial conditions based on the numerical results of hydrodynamical simulations of the common envelope phase, it was found that the shapes and sizes of the resulting nebula are very sensitive to the effective temperature of the remnant core, the mass-loss rate at the onset of the common envelope phase, and the mass ratio of the binary system. These parameters are related to the efficiency of the mass ejection after the spiral-in phase, the stellar evolutionary phase (i.e., RG, AGB, or TP-AGB), and the degree of departure from spherical symmetry in the stellar wind mass-loss process itself, respectively. It was also found that the shapes are mostly bipolar in the early phase of evolution, but that they can quickly transition to elliptical and barrel-type shapes. Solutions for nested lobes are found where the outer lobes are usually bipolar and the inner lobes are elliptical, bipolar, or barrel-type, a result due to the flow of the photo-evaporated gas from the equatorial region. Also, the lobes can be produced without the need for two distinct mass ejection events. In all the computations, the bulk of the mass is concentrated in the orbital or equatorial plane, in the form of a large toroid, which can be either neutral (early phases) or photoionized (late phases), depending of the evolutionary state of the system.

Experimental Study of the Compression Response of Fluted-Core Composite Panels with Joints

NASA Technical Reports Server (NTRS)

Schultz, Marc R.; Rose, Cheryl A.; Guzman, J. Carlos; McCarville, Douglas; Hilburger, Mark W.

2012-01-01

Fluted-core sandwich composites consist of integral angled web members spaced between laminate face sheets, and may have the potential to provide benefits over traditional sandwich composites for certain aerospace applications. However, fabrication of large autoclave-cured fluted-core cylindrical shells with existing autoclaves will require that the shells be fabricated in segments, and joined longitudinally to form a complete barrel. Two different longitudinal fluted-core joint designs were considered experimentally in this study. In particular, jointed fluted-core-composite panels were tested in longitudinal compression because longitudinal compression is the primary loading condition in dry launch-vehicle barrel sections. One of the joint designs performed well in comparison with unjointed test articles, and the other joint design failed at loads approximately 14% lower than unjointed test articles. The compression-after-impact (CAI) performance of jointed fluted-core composites was also investigated by testing test articles that had been subjected to 6 ft-lb impacts. It was found that such impacts reduced the load-carrying capability by 9% to 40%. This reduction is dependent on the joint concept, component flute size, and facesheet thickness.

30 CFR 256.43 - Chargeability for production.

Code of Federal Regulations, 2010 CFR

2010-07-01

....41 of this part, chargeability under § 256.46(g) of this part, 1.454 barrels of natural gas liquids... SULPHUR OR OIL AND GAS IN THE OUTER CONTINENTAL SHELF Issuance of Leases § 256.43 Chargeability for..., certificate of deposit for a security, fractional undivided interest in oil, gas, or other mineral rights, or...

Composite pipe to metal joint

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

Leslie, James C.; Leslie, II, James C.; Heard, James

A method for making a metal to composite tube joint including selecting an elongated interior fitting constructed with an exterior barrel, reduced in exterior diameter to form a distally facing annular shoulder and then projecting still further distally to form an interior sleeve having a radially outwardly facing bonding surface. Selecting an elongated metal outer sleeve formed proximally with a collar constructed for receipt over the barrel and increased in interior diameter and projecting distally to form an exterior sleeve having a radially inwardly facing bonding surface cooperating with the first bonding surface to form an annulus receiving an extremitymore » of a composite tube and a bond bonding the extremity of the tube to the bonding surfaces.« less

High precision optomechanical assembly using threads as mechanical reference

NASA Astrophysics Data System (ADS)

Lamontagne, Frédéric; Desnoyers, Nichola; Bergeron, Guy; Cantin, Mario

2016-09-01

A convenient method to assemble optomechanical components is to use threaded interface. For example, lenses are often secured inside barrels using threaded rings. In other cases, multiple optical sub-assemblies such as lens barrels can be threaded to each other. Threads have the advantage to provide a simple assembly method, to be easy to manufacture, and to offer a compact mechanical design. On the other hand, threads are not considered to provide accurate centering between parts because of the assembly clearance between the inner and outer threads. For that reason, threads are often used in conjunction with precision cylindrical surfaces to limit the radial clearance between the parts to be centered. Therefore, tight manufacturing tolerances are needed on these pilot diameters, which affect the cost of the optical assembly. This paper presents a new optomechanical approach that uses threads as mechanical reference. This innovative method relies on geometric principles to auto-center parts to each other with a very low centering error that is usually less than 5 μm. The method allows to auto-center an optical group in a main barrel, to perform an axial adjustment of an optical group inside a main barrel, and to perform stacking of multiple barrels. In conjunction with the lens auto-centering method that also used threads as a mechanical reference, this novel solution opens new possibilities to realize a variety of different high precision optomechanical assemblies at lower cost.

Edgewise Compression Testing of STIPS-0 (Structurally Integrated Thermal Protection System)

NASA Technical Reports Server (NTRS)

Brewer, Amy R.

2011-01-01

The Structurally Integrated Thermal Protection System (SITPS) task was initiated by the NASA Hypersonics Project under the Fundamental Aeronautics Program to develop a structural load-carrying thermal protection system for use in aerospace applications. The initial NASA concept for SITPS consists of high-temperature composite facesheets (outer and inner mold lines) with a light-weight insulated structural core. An edgewise compression test was performed on the SITPS-0 test article at room temperature using conventional instrumentation and methods in order to obtain panel-level mechanical properties and behavior of the panel. Three compression loadings (10, 20 and 37 kips) were applied to the SITPS-0 panel. The panel behavior was monitored using standard techniques and non-destructive evaluation methods such as photogrammetry and acoustic emission. The elastic modulus of the SITPS-0 panel was determined to be 1.146x106 psi with a proportional limit at 1039 psi. Barrel-shaped bending of the panel and partial delamination of the IML occurred under the final loading.

Results of NanTroSEIZE Expeditions Stages 1 & 2: Deep-sea Coring Operations on-board the Deep-sea Drilling Vessel Chikyu and Development of Coring Equipment for Stage 3

NASA Astrophysics Data System (ADS)

Shinmoto, Y.; Wada, K.; Miyazaki, E.; Sanada, Y.; Sawada, I.; Yamao, M.

2010-12-01

The Nankai-Trough Seismogenic Zone Experiment (NanTroSEIZE) has carried out several drilling expeditions in the Kumano Basin off the Kii-Peninsula of Japan with the deep-sea scientific drilling vessel Chikyu. Core sampling runs were carried out during the expeditions using an advanced multiple wireline coring system which can continuously core into sections of undersea formations. The core recovery rate with the Rotary Core Barrel (RCB) system was rather low as compared with other methods such as the Hydraulic Piston Coring System (HPCS) and Extended Shoe Coring System (ESCS). Drilling conditions such as hole collapse and sea conditions such as high ship-heave motions need to be analyzed along with differences in lithology, formation hardness, water depth and coring depth in order to develop coring tools, such as the core barrel or core bit, that will yield the highest core recovery and quality. The core bit is especially important in good recovery of high quality cores, however, the PDC cutters were severely damaged during the NanTroSEIZE Stages 1 & 2 expeditions due to severe drilling conditions. In the Stage 1 (riserless coring) the average core recovery was rather low at 38 % with the RCB and many difficulties such as borehole collapse, stick-slip and stuck pipe occurred, causing the damage of several of the PDC cutters. In Stage 2, a new design for the core bit was deployed and core recovery was improved at 67 % for the riserless system and 85 % with the riser. However, due to harsh drilling conditions, the PDC core bit and all of the PDC cutters were completely worn down. Another original core bit was also deployed, however, core recovery performance was low even for plate boundary core samples. This study aims to identify the influence of the RCB system specifically on the recovery rates at each of the holes drilled in the NanTroSEIZE coring expeditions. The drilling parameters such as weight-on-bit, torque, rotary speed and flow rate, etc., were analyzed and conditions such as formation, tools, and sea conditions which directly affect core recovery have been categorized. Also discussed will be the further development of such coring equipment as the core bit and core barrel for the NanTroSEIZE Stage 3 expeditions, which aim to reach a depth of 7000 m-below the sea floor into harder formations under extreme drilling conditions.

Gibbs motif sampling: detection of bacterial outer membrane protein repeats.

PubMed Central

Neuwald, A. F.; Liu, J. S.; Lawrence, C. E.

1995-01-01

The detection and alignment of locally conserved regions (motifs) in multiple sequences can provide insight into protein structure, function, and evolution. A new Gibbs sampling algorithm is described that detects motif-encoding regions in sequences and optimally partitions them into distinct motif models; this is illustrated using a set of immunoglobulin fold proteins. When applied to sequences sharing a single motif, the sampler can be used to classify motif regions into related submodels, as is illustrated using helix-turn-helix DNA-binding proteins. Other statistically based procedures are described for searching a database for sequences matching motifs found by the sampler. When applied to a set of 32 very distantly related bacterial integral outer membrane proteins, the sampler revealed that they share a subtle, repetitive motif. Although BLAST (Altschul SF et al., 1990, J Mol Biol 215:403-410) fails to detect significant pairwise similarity between any of the sequences, the repeats present in these outer membrane proteins, taken as a whole, are highly significant (based on a generally applicable statistical test for motifs described here). Analysis of bacterial porins with known trimeric beta-barrel structure and related proteins reveals a similar repetitive motif corresponding to alternating membrane-spanning beta-strands. These beta-strands occur on the membrane interface (as opposed to the trimeric interface) of the beta-barrel. The broad conservation and structural location of these repeats suggests that they play important functional roles. PMID:8520488

Recent Increases in Snow Accumulation and Decreases in Sea-Ice Concentration Recorded in a Coastal NW Greenland Ice Core

NASA Astrophysics Data System (ADS)

Osterberg, E. C.; Thompson, J. T.; Wong, G. J.; Hawley, R. L.; Kelly, M. A.; Lutz, E.; Howley, J.; Ferris, D. G.

2013-12-01

A significant rise in summer temperatures over the past several decades has led to widespread retreat of the Greenland Ice Sheet (GIS) margin and surrounding sea ice. Recent observations from geodetic stations and GRACE show that ice mass loss progressed from South Greenland up to Northwest Greenland by 2005 (Khan et al., 2010). Observations from meteorological stations at the U.S. Thule Air Force Base, remote sensing platforms, and climate reanalyses indicate a 3.5C mean annual warming in the Thule region and a 44% decrease in summer (JJAS) sea-ice concentrations in Baffin Bay from 1980-2010. Mean annual precipitation near Thule increased by 12% over this interval, with the majority of the increase occurring in fall (SON). To improve projections of future ice loss and sea-level rise in a warming climate, we are currently developing multi-proxy records (lake sediment cores, ice cores, glacial geologic data, glaciological models) of Holocene climate variability and cryospheric response in NW Greenland, with a focus on past warm periods. As part of our efforts to develop a millennial-length ice core paleoclimate record from the Thule region, we collected and analyzed snow pit samples and short firn cores (up to 20 m) from the coastal region of the GIS (2Barrel site; 76.9317 N, 63.1467 W) and the summit of North Ice Cap (76.938 N, 67.671 W) in 2011 and 2012, respectively. The 2Barrel ice core was sampled using a continuous ice core melting system at Dartmouth, and subsequently analyzed for major anion and trace element concentrations and stable water isotope ratios. Here we show that the 2Barrel ice core spanning 1990-2010 records a 25% increase in mean annual snow accumulation, and is positively correlated (r = 0.52, p<0.01) with ERA-Interim precipitation. The 2Barrel annual sea-salt Na concentration is strongly correlated (r = 0.5-0.8, p<0.05) with summer and fall sea-ice concentrations in northern Baffin Bay near Thule (Figure 1). We hypothesize that the positive correlation represents a significant Na contribution from frost flowers growing on fall frazil ice. Ongoing analyses will evaluate the relationship between MSA concentrations and sea ice extent. Our results show that a deep ice core collected from this dynamic and climate-sensitive region of NW Greenland would produce a valuable record of late Holocene climate and sea ice extent.

Purification and Bicelle Crystallization for Structure Determination of the E. coli Outer Membrane Protein TamA.

PubMed

Gruss, Fabian; Hiller, Sebastian; Maier, Timm

2015-01-01

TamA is an Omp85 protein involved in autotransporter assembly in the outer membrane of Escherichia coli. It comprises a C-terminal 16-stranded transmembrane β-barrel as well as three periplasmic POTRA domains, and is a challenging target for structure determination. Here, we present a method for crystal structure determination of TamA, including recombinant expression in E. coli, detergent extraction, chromatographic purification, and bicelle crystallization in combination with seeding. As a result, crystals in space group P21212 are obtained, which diffract to 2.3 Å resolution. This protocol also serves as a template for structure determination of other outer membrane proteins, in particular of the Omp85 family.

7. Another picture of workers laying up the graphite core ...

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

7. Another picture of workers laying up the graphite core of the 105-B pile. This view is towards the rear of the pile. The gun barrels can be seen protruding into the pile. D-3047 - B Reactor, Richland, Benton County, WA

GRC-2010-C-01237

NASA Image and Video Library

2006-03-29

Fiber-Reinforced-Foam (FRF) Core Composite Sandwich Panel Concept for Advanced Composites Technologies Project - Preliminary Manufacturing Demonstration Articles for Ares V Payload Shroud Barrel Acreage Structure

GRC-2010-C-01234

NASA Image and Video Library

2006-03-29

Fiber-Reinforced-Foam (FRF) Core Composite Sandwich Panel Concept for Advanced Composites Technologies Project - Preliminary Manufacturing Demonstration Articles for Ares V Payload Shroud Barrel Acreage Structure

GRC-2010-C-01233

NASA Image and Video Library

2006-03-29

Fiber-Reinforced-Foam (FRF) Core Composite Sandwich Panel Concept for Advanced Composites Technologies Project - Preliminary Manufacturing Demonstration Articles for Ares V Payload Shroud Barrel Acreage Structure

Method of making a composite tube to metal joint

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

Leslie, James C.; Leslie, II, James C.; Heard, James

A method for making a metal to composite tube joint including selecting an elongated interior fitting constructed with an exterior barrel, reduced in exterior diameter to form a distally facing annular shoulder and then projecting still further distally to form an interior sleeve having a radially outwardly facing bonding surface. Selecting an elongated metal outer sleeve formed proximally with a collar constructed for receipt over the barrel and increased in interior diameter and projecting distally to form an exterior sleeve having a radially inwardly facing bonding surface cooperating with the first bonding surface to form an annulus receiving an extremitymore » of a composite tube and a bond bonding the extremity of the tube to the bonding surfaces.« less

6. Workers laying up the graphite core of the 105B ...

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

6. Workers laying up the graphite core of the 105-B file. In the lower-left can be seen a portion of the rear face of the pile, the top of its shielding wall, and the gun barrels protruding through it. The inside of the front face of the pile and its gun barrels can be seen toward the upper-right side. The angled top of the front shielding wall can be seen in the picture. All four walls were "stepped" in this manner where they joined with another wall or the ceiling to form a "labyrinth" joint, so that radiation would not have a straight route through any gaps in the joints. D-3045 - B Reactor, Richland, Benton County, WA

Bipartite Topology of Treponema pallidum Repeat Proteins C/D and I

PubMed Central

Anand, Arvind; LeDoyt, Morgan; Karanian, Carson; Luthra, Amit; Koszelak-Rosenblum, Mary; Malkowski, Michael G.; Puthenveetil, Robbins; Vinogradova, Olga; Radolf, Justin D.

2015-01-01

We previously identified Treponema pallidum repeat proteins TprC/D, TprF, and TprI as candidate outer membrane proteins (OMPs) and subsequently demonstrated that TprC is not only a rare OMP but also forms trimers and has porin activity. We also reported that TprC contains N- and C-terminal domains (TprCN and TprCC) orthologous to regions in the major outer sheath protein (MOSPN and MOSPC) of Treponema denticola and that TprCC is solely responsible for β-barrel formation, trimerization, and porin function by the full-length protein. Herein, we show that TprI also possesses bipartite architecture, trimeric structure, and porin function and that the MOSPC-like domains of native TprC and TprI are surface-exposed in T. pallidum, whereas their MOSPN-like domains are tethered within the periplasm. TprF, which does not contain a MOSPC-like domain, lacks amphiphilicity and porin activity, adopts an extended inflexible structure, and, in T. pallidum, is tightly bound to the protoplasmic cylinder. By thermal denaturation, the MOSPN and MOSPC-like domains of TprC and TprI are highly thermostable, endowing the full-length proteins with impressive conformational stability. When expressed in Escherichia coli with PelB signal sequences, TprC and TprI localize to the outer membrane, adopting bipartite topologies, whereas TprF is periplasmic. We propose that the MOSPN-like domains enhance the structural integrity of the cell envelope by anchoring the β-barrels within the periplasm. In addition to being bona fide T. pallidum rare outer membrane proteins, TprC/D and TprI represent a new class of dual function, bipartite bacterial OMP. PMID:25805501

Outer-membrane Transport of Aromatic Hydrocarbons as a First Step in Biodegradation

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

Hearn,E.; Patel, D.; van den Berg, B.

Bacterial biodegradation of hydrocarbons, an important process for environmental remediation, requires the passage of hydrophobic substrates across the cell membrane. Here, we report crystal structures of two outer membrane proteins, Pseudomonas putida TodX and Ralstonia pickettii TbuX, which have been implicated in hydrocarbon transport and are part of a subfamily of the FadL fatty acid transporter family. The structures of TodX and TbuX show significant differences with those previously determined for Escherichia coli FadL, which may provide an explanation for the substrate-specific transport of TodX and TbuX observed with in vivo transport assays. The TodX and TbuX structures revealed 14-strandedmore » {beta}-barrels with an N-terminal hatch domain blocking the barrel interior. A hydrophobic channel with bound detergent molecules extends from the extracellular surface and is contiguous with a passageway through the hatch domain, lined by both hydrophobic and polar or charged residues. The TodX and TbuX structures support a mechanism for transport of hydrophobic substrates from the extracellular environment to the periplasm via a channel through the hatch domain.« less

A time-based front-end ASIC for the silicon micro strip sensors of the bar PANDA Micro Vertex Detector

NASA Astrophysics Data System (ADS)

Di Pietro, V.; Brinkmann, K.-Th.; Riccardi, A.; Ritman, J.; Rivetti, A.; Rolo, M. D.; Stockmanns, T.; Zambanini, A.

2016-03-01

The bar PANDA (Antiproton Annihilation at Darmstadt) experiment foresees many detectors for tracking, particle identification and calorimetry. Among them, the innermost is the MVD (Micro Vertex Detector) responsible for a precise tracking and the reconstruction of secondary vertices. This detector will be built from both hybrid pixel (two inner barrels and six forward disks) and double-sided micro strip (two outer barrels and outer rim of the last two disks) silicon sensors. A time-based approach has been chosen for the readout ASIC of the strip sensors. The PASTA (bar PANDA Strip ASIC) chip aims at high resolution time-stamping and charge information through the Time over Threshold (ToT) technique. It benefits from a Time to Digital Converter (TDC) allowing a time bin width down to 50 ps. The analog front-end was designed to serve both n-type and p-type strips and the performed simulations show remarkable performances in terms of linearity and electronic noise. The TDC consists of an analog interpolator, a digital local controller, and a digital global controller as the common back-end for all of the 64 channels.

Assembly of 5.5-Meter Diameter Developmental Barrel Segments for the Ares I Upper Stage

NASA Technical Reports Server (NTRS)

Carter, Robert W.

2011-01-01

Full scale assembly welding of Ares I Upper Stage 5.5-Meter diameter cryogenic tank barrel segments has been performed at the Marshall Space Flight Center (MSFC). One full-scale developmental article produced under the Ares 1 Upper Stage project is the Manufacturing Demonstration Article (MDA) Barrel. This presentation will focus on the welded assembly of this barrel section, and associated lessons learned. Among the MDA articles planned on the Ares 1 Program, the Barrel was the first to be completed, primarily because the process of manufacture from piece parts (barrel panels) utilized the most mature friction stir process planned for use on the Ares US program: Conventional fixed pin Friction Stir Welding (FSW). This process is in use on other space launch systems, including the Shuttle s External Tank, the Delta IV common booster core, the Delta II, and the Atlas V rockets. The goals for the MDA Barrel development were several fold: 1) to prove out Marshall Space Flight Center s new Vertical Weld Tool for use in manufacture of cylindrical barrel sections, 2) to serve as a first run for weld qualification to a new weld specification, and 3) to provide a full size cylindrical section for downstream use in precision cleaning and Spray-on Foam Insulation development. The progression leading into the welding of the full size barrel included sub scale panel welding, subscale cylinder welding, a full length confidence weld, and finally, the 3 seamed MDA barrel processing. Lessons learned on this MDA program have been carried forward into the production tooling for the Ares 1 US Program, and in the use of the MSFC VWT in processing other large scale hardware, including two 8.4 meter diameter Shuttle External Tank barrel sections that are currently being used in structural analysis to validate shell buckling models.

Sprayed skin turbine component

DOEpatents

Allen, David B

2013-06-04

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

Liquid Iron Alloys with Hydrogen at Outer Core Conditions by First Principles

NASA Astrophysics Data System (ADS)

Umemoto, K.; Hirose, K.

2015-12-01

Since the density of the outer core deduced from seismic data is about 10% lower than that of pure iron at core pressures and temperatures (P-T), it is widely believed that the outer core includes one or more light elements. Although intensive experimental and theoretical studies have been performed so far, the light element in the core has not yet been identified. Comparison of the density and sound velocity of liquid iron alloys with observations, such as the PREM, is a promising way to determine the species and quantity of light alloying component(s) in the outer core. Here we report the results of a first-principles molecular dynamics study on liquid iron alloyed with hydrogen, one of candidates of the light elements. Hydrogen had been much less studied than other candidates. However, hydrogen has been known to reduce the melting temperature of Fe-H solid [1]. Furthermore, very recently, Nomura et al. argued that the outer core may include 24 at.% H in order to be molten under relatively low temperature (< 3600 K) [2]. Since then hydrogen has attracted strong interests. We clarify the effects of hydrogen on density and sound velocity of liquid iron alloys under outer core P-T conditions. It is shown that ~1 wt% hydrogen can reproduce PREM density and sound velocity simultaneously very well. In addition, we show the presence of hydrogen rather reduces Gruneisen parameters. It indicates that, if hydrogen exists in the outer core, temperature profile of the outer core could be changed considerably from one estimated so far. [1] Sakamaki, K., E. Takahashi, Y. Nakajima, Y. Nishihara, K. Funakoshi, T. Suzuki, and Y. Fukai, Phys. Earth Planet. Inter., 174, 192-201 (2009). [2] Nomura, R., K. Hirose, K. Uesugi, Y. Ohishi, A. Tsuchiyama, A. Miyake, and Y. Ueno, Science 31, 522-525 (2014).

Discovery and Biogeochemical Investigation of Chlorinated Industrial Waste in the Deep Ocean

NASA Astrophysics Data System (ADS)

Lemkau, K. L.; Kivenson, V. B.; Carmichael, C. A.; Aeppli, C.; Bagby, S. C.; Wentz, K.; Baxter, A.; Paul, B. G.; Pizarro, O.; Yoerger, D.; Reddy, C. M.; Valentine, D. L.

2014-12-01

Prior to the 1972 US ban on DDT use, dumping of solid waste from DDT manufacturing was permitted at two locations off the coast of Southern California. Between 1947 and 1961, 37-53 million liters of DDT waste (containing an estimated 350-700 metric tons of DDT) were disposed of at these deep-ocean dumpsites. In 2011 and 2013 we explored these sites with ROV Jason and AUV Sentry, discovering the remains of ~60 barrels scattered across dumpsite 2. Strikingly, many of these barrels were surrounded by distinctive white rings suggestive of microbial activity. We describe our identification and exploration of these sites and present results from chemical analysis of sediment cores collected around waste barrels. DDT and its degradation products (DDE, DDD and DDMU) were detectable at ng to μg per gram concentrations and showed spatial trends with both distance and depth around barrels. Analysis of microbial community DNA provides a first look at the role of microbiological processes in shaping these trends.

Praying Mantis Bending Core Breakoff and Retention Mechanism

NASA Technical Reports Server (NTRS)

Badescu, Mircea; Sherrit, Stewart; Bar-Cohen, Yoseph; Bao, Xiaoqi; Lindermann, Randel A.

2011-01-01

Sampling cores requires the controlled breakoff of the core at a known location with respect to the drill end. An additional problem is designing a mechanism that can be implemented at a small scale, yet is robust and versatile enough to be used for a variety of core samples. The new design consists of a set of tubes (a drill tube, an outer tube, and an inner tube) and means of sliding the inner and outer tubes axially relative to each other. Additionally, a sample tube can be housed inside the inner tube for storing the sample. The inner tube fits inside the outer tube, which fits inside the drill tube. The inner and outer tubes can move axially relative to each other. The inner tube presents two lamellae with two opposing grabbing teeth and one pushing tooth. The pushing tooth is offset axially from the grabbing teeth. The teeth can move radially and their motion is controlled by the outer tube. The outer tube presents two lamellae with radial extrusions to control the inner tube lamellae motion. In breaking the core, the mechanism creates two support points (the grabbing teeth and the bit tip) and one push point. The core is broken in bending. The grabbing teeth can also act as a core retention mechanism. The praying mantis that is disclosed herein is an active core breaking/retention mechanism that requires only one additional actuator other than the drilling actuator. It can break cores that are attached to the borehole bottom as

An oilspill risk analysis for the South Atlantic (proposed sale 78) outer continental shelf lease area

USGS Publications Warehouse

Samuels, W.B.

1982-01-01

An oilspill risk analysis was conducted for the South Atlantic (proposed sale 78) Outer Continental Shelf (OCS) lease area. The analysis considered the probability of spill occurrences based on historical trends; likely movement of oil slicks based on a climatological model ; and locations of environmental resources which could be vulnerable to spilled oil. The times between spill occurrence and contact with resources were estimated to aid analysts in estimating slick characteristics. Critical assumptions made for this particular analysis were: (1) that oil exists in the lease area, (2) that either 0.228 billion (mean case) or 1.14 billion (high case) barrels of oil will be found and produced from tracts sold in sale 78, and (3) that all the oil will be found either in the northern or the southern portion of the lease area. On the basis of these resource estimates, it was estimated that 1 to 5 oilspills of 1,000 barrels or greater will occur over the 25 to 30-year production life of the proposed sale 78 tracts. The results also depend upon the routes and methods chosen to transport oil from OCS platforms to shore. Given the above assumptions, the estimated probability that one or more oilspills of 1,000 barrels or larger will occur and contact land after being at sea less than 30 days is less than 15 percent for all cases considered; for spills 10,000 barrels or larger, the probability is less than 10 percent. These probabilities also reflect the following assumptions: oilspills remain intact for up to 30 days, do not weather, and are not cleaned up. It is noteworthy that over 80 percent of the risk of oilspill occurrence from proposed sale 78 is due to transportation rather than production of oil. In addition, the risks of oilspill occurrence from proposed sale 78 (mean resource estimate) are less than one-tenth of the risks of existing tanker transportation of crude oil imports and refined products in the South Atlantic area.

Results from the USIP_UH contribution to the BARREL-4 campaign

NASA Astrophysics Data System (ADS)

Behrend, C. C.; Bering, E. A., III; Ehteshami, A.; Fenton, A.; Gamblin, R.; Greer, M.; Mathur, S.; Glennie, C. L.; Velasquez, B.; Marpaung, J.; Lalata, M. C.

2016-12-01

The Undergraduate Student Instrumentation Project (USIP) at the University of Houston sent a team to Kiruna, Sweden to participate with NASA/Dartmouth's BARREL-4 campaign in August 2016. BARREL-4's primary instrument is an MeV x-ray scintillation counter. The team has provided two different experiments to be flown, a dual frequency GPS receiver to calculate total electron content and a Very Low Frequency (VLF) receiver to measure the VLF emissions associated with electron precipitation. TEC is calculated via finding pseudo-ranges comparing the sent and received signals from passing satellites. The VLF receiver has an air-core magnetic loop antenna that utilizes a transformer coupled with an integrating pre-amp which is then recorded to a standard music recorder. The presentation will include a summary of observations.

Periplasmic quality control in biogenesis of outer membrane proteins.

PubMed

Lyu, Zhi Xin; Zhao, Xin Sheng

2015-04-01

The β-barrel outer membrane proteins (OMPs) are integral membrane proteins that reside in the outer membrane of Gram-negative bacteria and perform a diverse range of biological functions. Synthesized in the cytoplasm, OMPs must be transported across the inner membrane and through the periplasmic space before they are assembled in the outer membrane. In Escherichia coli, Skp, SurA and DegP are the most prominent factors identified to guide OMPs across the periplasm and to play the role of quality control. Although extensive genetic and biochemical analyses have revealed many basic functions of these periplasmic proteins, the mechanism of their collaboration in assisting the folding and insertion of OMPs is much less understood. Recently, biophysical approaches have shed light on the identification of the intricate network. In the present review, we summarize recent advances in the characterization of these key factors, with a special emphasis on the multifunctional protein DegP. In addition, we present our proposed model on the periplasmic quality control in biogenesis of OMPs.

Eukaryote-wide sequence analysis of mitochondrial β-barrel outer membrane proteins.

PubMed

Imai, Kenichiro; Fujita, Naoya; Gromiha, M Michael; Horton, Paul

2011-01-28

The outer membranes of mitochondria are thought to be homologous to the outer membranes of Gram negative bacteria, which contain 100's of distinct families of β-barrel membrane proteins (BOMPs) often forming channels for transport of nutrients or drugs. However, only four families of mitochondrial BOMPs (MBOMPs) have been confirmed to date. Although estimates as high as 100 have been made in the past, the number of yet undiscovered MBOMPs is an open question. Fortunately, the recent discovery of a membrane integration signal (the β-signal) for MBOMPs gave us an opportunity to look for undiscovered MBOMPs. We present the results of a comprehensive survey of eukaryotic protein sequences intended to identify new MBOMPs. Our search employs recent results on β-signals as well as structural information and a novel BOMP predictor trained on both bacterial and mitochondrial BOMPs. Our principal finding is circumstantial evidence suggesting that few MBOMPs remain to be discovered, if one assumes that, like known MBOMPs, novel MBOMPs will be monomeric and β-signal dependent. In addition to this, our analysis of MBOMP homologs reveals some exceptions to the current model of the β-signal, but confirms its consistent presence in the C-terminal region of MBOMP proteins. We also report a β-signal independent search for MBOMPs against the yeast and Arabidopsis proteomes. We find no good candidates MBOMPs in yeast but the Arabidopsis results are less conclusive. Our results suggest there are no remaining MBOMPs left to discover in yeast; and if one assumes all MBOMPs are β-signal dependent, few MBOMP families remain undiscovered in any sequenced organism.

Chloroplast Omp85 proteins change orientation during evolution

PubMed Central

Sommer, Maik S.; Daum, Bertram; Gross, Lucia E.; Weis, Benjamin L. M.; Mirus, Oliver; Abram, Lars; Maier, Uwe-G.; Kühlbrandt, Werner; Schleiff, Enrico

2011-01-01

The majority of outer membrane proteins (OMPs) from Gram-negative bacteria and many of mitochondria and chloroplasts are β-barrels. Insertion and assembly of these proteins are catalyzed by the Omp85 protein family in a seemingly conserved process. All members of this family exhibit a characteristic N-terminal polypeptide-transport–associated (POTRA) and a C-terminal 16-stranded β-barrel domain. In plants, two phylogenetically distinct and essential Omp85's exist in the chloroplast outer membrane, namely Toc75-III and Toc75-V. Whereas Toc75-V, similar to the mitochondrial Sam50, is thought to possess the original bacterial function, its homolog, Toc75-III, evolved to the pore-forming unit of the TOC translocon for preprotein import. In all current models of OMP biogenesis and preprotein translocation, a topology of Omp85 with the POTRA domain in the periplasm or intermembrane space is assumed. Using self-assembly GFP-based in vivo experiments and in situ topology studies by electron cryotomography, we show that the POTRA domains of both Toc75-III and Toc75-V are exposed to the cytoplasm. This unexpected finding explains many experimental observations and requires a reevaluation of current models of OMP biogenesis and TOC complex function. PMID:21825140

A Bioinformatic Strategy for the Detection, Classification and Analysis of Bacterial Autotransporters

PubMed Central

Celik, Nermin; Webb, Chaille T.; Leyton, Denisse L.; Holt, Kathryn E.; Heinz, Eva; Gorrell, Rebecca; Kwok, Terry; Naderer, Thomas; Strugnell, Richard A.; Speed, Terence P.; Teasdale, Rohan D.; Likić, Vladimir A.; Lithgow, Trevor

2012-01-01

Autotransporters are secreted proteins that are assembled into the outer membrane of bacterial cells. The passenger domains of autotransporters are crucial for bacterial pathogenesis, with some remaining attached to the bacterial surface while others are released by proteolysis. An enigma remains as to whether autotransporters should be considered a class of secretion system, or simply a class of substrate with peculiar requirements for their secretion. We sought to establish a sensitive search protocol that could identify and characterize diverse autotransporters from bacterial genome sequence data. The new sequence analysis pipeline identified more than 1500 autotransporter sequences from diverse bacteria, including numerous species of Chlamydiales and Fusobacteria as well as all classes of Proteobacteria. Interrogation of the proteins revealed that there are numerous classes of passenger domains beyond the known proteases, adhesins and esterases. In addition the barrel-domain-a characteristic feature of autotransporters-was found to be composed from seven conserved sequence segments that can be arranged in multiple ways in the tertiary structure of the assembled autotransporter. One of these conserved motifs overlays the targeting information required for autotransporters to reach the outer membrane. Another conserved and diagnostic motif maps to the linker region between the passenger domain and barrel-domain, indicating it as an important feature in the assembly of autotransporters. PMID:22905239

Secretion of the Intimin Passenger Domain Is Driven by Protein Folding*

PubMed Central

Leo, Jack C.; Oberhettinger, Philipp; Yoshimoto, Shogo; Udatha, D. B. R. K. Gupta; Morth, J. Preben; Schütz, Monika; Hori, Katsutoshi

2016-01-01

Intimin is an essential adhesin of attaching and effacing organisms such as entropathogenic Escherichia coli. It is also the prototype of type Ve secretion or inverse autotransport, where the extracellular C-terminal region or passenger is exported with the help of an N-terminal transmembrane β-barrel domain. We recently reported a stalled secretion intermediate of intimin, where the passenger is located in the periplasm but the β-barrel is already inserted into the membrane. Stalling of this mutant is due to the insertion of an epitope tag at the very N terminus of the passenger. Here, we examined how this insertion disrupts autotransport and found that it causes misfolding of the N-terminal immunoglobulin (Ig)-like domain D00. We could also stall the secretion by making an internal deletion in D00, and introducing the epitope tag into the second Ig-like domain, D0, also resulted in reduced passenger secretion. In contrast to many classical autotransporters, where a proximal folding core in the passenger is required for secretion, the D00 domain is dispensable, as the passenger of an intimin mutant lacking D00 entirely is efficiently exported. Furthermore, the D00 domain is slightly less stable than the D0 and D1 domains, unfolding at ∼200 piconewtons (pN) compared with ∼250 pN for D0 and D1 domains as measured by atomic force microscopy. Our results support a model where the secretion of the passenger is driven by sequential folding of the extracellular Ig-like domains, leading to vectorial transport of the passenger domain across the outer membrane in an N to C direction. PMID:27466361

Structure of the periplasmic adaptor protein from a major facilitator superfamily (MFS) multidrug efflux pump.

PubMed

Hinchliffe, Philip; Greene, Nicholas P; Paterson, Neil G; Crow, Allister; Hughes, Colin; Koronakis, Vassilis

2014-08-25

Periplasmic adaptor proteins are key components of bacterial tripartite efflux pumps. The 2.85 Å resolution structure of an MFS (major facilitator superfamily) pump adaptor, Aquifex aeolicus EmrA, shows linearly arranged α-helical coiled-coil, lipoyl, and β-barrel domains, but lacks the fourth membrane-proximal domain shown in other pumps to interact with the inner membrane transporter. The adaptor α-hairpin, which binds outer membrane TolC, is exceptionally long at 127 Å, and the β-barrel contains a conserved disordered loop. The structure extends the view of adaptors as flexible, modular components that mediate diverse pump assembly, and suggests that in MFS tripartite pumps a hexamer of adaptors could provide a periplasmic seal. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

An oilspill risk analysis for the North Atlantic outer continental shelf lease area

USGS Publications Warehouse

Smith, Richard Allmon; Slack, James Richard; Davis, Robert K.

1976-01-01

The Federal Government has proposed to lease 1,172,795 acres of Outer Continental Shelf (OCS) lands on Georges Bank off the New England Coast for oil and gas development. Estimated recoverable petroleum resources for the proposed 206 tract sale area range from 180 to 650 million barrels. Contingent upon actual discovery of this quantity of oil, production is expected to span a period of about 20 years. An oilspill risk analysis was conducted to determine relative environmental hazards of developing oil in the North Atlantic Outer Continental Shelf lease area. The study analyzed probability of spill occurrence, likely path of pollutants from spills, and locations in space and time of recreational and biological resources likely to be vulnerable. These results are combined to yield estimates of the overall oilspill risk associated with development of the lease area. (Woodard-USGS)

Visible light emission measurements from a dense electrothermal launcher plasma

NASA Astrophysics Data System (ADS)

Hankins, O. E.; Bourham, M. A.; Earnhart, J.; Gilligan, J. G.

1993-01-01

Measurements of the visible light emission from dense, weakly non-ideal plasmas have been performed on the experimental electrothermal launcher device 'SIRENS'. The plasma is created by the ablation or a Lexan insulator in the source, which then flows through a cylindrical barrel which serves as the material sample. Visible light emission spectra have been observed both in-bore and from the muzzle flash or the barrel, and from the flash or the source. Due to high plasma opacity (the plasma emits as a near blackbody) and absorption by the molecular components of the vapor shield, the hotter core or the arc has been difficult to observe. Recent measurements along the axis or the device indicate time-averaged plasma temperatures in the barrel or about 1 eV for lower energy shots, which agree with experimental measurements of the average heat flux and plasma conductivity along the barrel. Measurements or visible emission from the source indicate time averaged temperatures of 1 to 2 eV which agree with the theoretical estimates derived from ablated mass measurements and calculated estimates derived from plasma conductivity measurements.

The melting curve of iron to 250 gigapascals - A constraint on the temperature at earth's center

NASA Technical Reports Server (NTRS)

Williams, Quentin; Jeanloz, Raymond; Bass, Jay; Svendsen, Bob; Ahrens, Thomas J.

1987-01-01

The melting curve of iron, the primary constituent of earth's core, has been measured to pressures of 250 gigapascals with a combination of static and dynamic techniques. The melting temperature of iron at the pressure of the core-mantle boundary (136 GPa) is 4800 + or - 200 K, whereas at the inner core-outer core boundary (330 GPa), it is 7600 + or - 500 K. A melting temperature for iron-rich alloy of 6600 K at the inner core-outer core boundary and a maximum temperature of 6900 K at earth's center are inferred. This latter value is the first experimental upper bound on the temperature at earth's center, and these results imply that the temperature of the lower mantle is significantly less than that of the outer core.

Structure of Rhodococcus equi virulence-associated protein B (VapB) reveals an eight-stranded antiparallel β-barrel consisting of two Greek-key motifs

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

Geerds, Christina; Wohlmann, Jens; Haas, Albert

The structure of VapB, a member of the Vap protein family that is involved in virulence of the bacterial pathogen R. equi, was determined by SAD phasing and reveals an eight-stranded antiparallel β-barrel similar to avidin, suggestive of a binding function. Made up of two Greek-key motifs, the topology of VapB is unusual or even unique. Members of the virulence-associated protein (Vap) family from the pathogen Rhodococcus equi regulate virulence in an unknown manner. They do not share recognizable sequence homology with any protein of known structure. VapB and VapA are normally associated with isolates from pigs and horses, respectively.more » To contribute to a molecular understanding of Vap function, the crystal structure of a protease-resistant VapB fragment was determined at 1.4 Å resolution. The structure was solved by SAD phasing employing the anomalous signal of one endogenous S atom and two bound Co ions with low occupancy. VapB is an eight-stranded antiparallel β-barrel with a single helix. Structural similarity to avidins suggests a potential binding function. Unlike other eight- or ten-stranded β-barrels found in avidins, bacterial outer membrane proteins, fatty-acid-binding proteins and lysozyme inhibitors, Vaps do not have a next-neighbour arrangement but consist of two Greek-key motifs with strand order 41238567, suggesting an unusual or even unique topology.« less

Horizontal baffle for nuclear reactors

DOEpatents

Rylatt, John A.

1978-01-01

A horizontal baffle disposed in the annulus defined between the core barrel and the thermal liner of a nuclear reactor thereby physically separating the outlet region of the core from the annular area below the horizontal baffle. The horizontal baffle prevents hot coolant that has passed through the reactor core from thermally damaging apparatus located in the annulus below the horizontal baffle by utilizing the thermally induced bowing of the horizontal baffle to enhance sealing while accommodating lateral motion of the baffle base plate.

The thermal evolution of Mercury's Fe-Si core

NASA Astrophysics Data System (ADS)

Knibbe, Jurriën Sebastiaan; van Westrenen, Wim

2018-01-01

We have studied the thermal and magnetic field evolution of planet Mercury with a core of Fe-Si alloy to assess whether an Fe-Si core matches its present-day partially molten state, Mercury's magnetic field strength, and the observed ancient crustal magnetization. The main advantages of an Fe-Si core, opposed to a previously assumed Fe-S core, are that a Si-bearing core is consistent with the highly reduced nature of Mercury and that no compositional convection is generated upon core solidification, in agreement with magnetic field indications of a stable layer at the top of Mercury's core. This study also present the first implementation of a conductive temperature profile in the core where heat fluxes are sub-adiabatic in a global thermal evolution model. We show that heat migrates from the deep core to the outer part of the core as soon as heat fluxes at the outer core become sub-adiabatic. As a result, the deep core cools throughout Mercury's evolution independent of the temperature evolution at the core-mantle boundary, causing an early start of inner core solidification and magnetic field generation. The conductive layer at the outer core suppresses the rate of core growth after temperature differences between the deep and shallow core are relaxed, such that a magnetic field can be generated until the present. Also, the outer core and mantle operate at higher temperatures than previously thought, which prolongs mantle melting and mantle convection. The results indicate that S is not a necessary ingredient of Mercury's core, bringing bulk compositional models of Mercury more in line with reduced meteorite analogues.

Experimental constraints on light elements in the Earth’s outer core

PubMed Central

Zhang, Youjun; Sekine, Toshimori; He, Hongliang; Yu, Yin; Liu, Fusheng; Zhang, Mingjian

2016-01-01

Earth’s outer core is liquid and dominantly composed of iron and nickel (~5–10 wt%). Its density, however, is ~8% lower than that of liquid iron, and requires the presence of a significant amount of light element(s). A good way to specify the light element(s) is a direct comparison of density and sound velocity measurements between seismological data and those of possible candidate compositions at the core conditions. We report the sound velocity measurements of a model core composition in the Fe-Ni-Si system at the outer core conditions by shock-wave experiments. Combining with the previous studies, we found that the best estimate for the outer core’s light elements is ~6 wt% Si, ~2 wt% S, and possible ~1–2.5 wt% O. This composition satisfies the requirements imposed by seismology, geochemistry, and some models of the early core formation. This finding may help us to further constrain the thermal structure of the Earth and the models of Earth’s core formation. PMID:26932596

Shock Compression and Melting of an Fe-Ni-Si Alloy: Implications for the Temperature Profile of the Earth's Core and the Heat Flux Across the Core-Mantle Boundary

NASA Astrophysics Data System (ADS)

Zhang, Youjun; Sekine, Toshimori; Lin, Jung-Fu; He, Hongliang; Liu, Fusheng; Zhang, Mingjian; Sato, Tomoko; Zhu, Wenjun; Yu, Yin

2018-02-01

Understanding the melting behavior and the thermal equation of state of Fe-Ni alloyed with candidate light elements at conditions of the Earth's core is critical for our knowledge of the region's thermal structure and chemical composition and the heat flow across the liquid outer core into the lowermost mantle. Here we studied the shock equation of state and melting curve of an Fe-8 wt% Ni-10 wt% Si alloy up to 250 GPa by hypervelocity impacts with direct velocity and reliable temperature measurements. Our results show that the addition of 10 wt% Si to Fe-8 wt% Ni alloy slightly depresses the melting temperature of iron by 200-300 (±200) K at the core-mantle boundary ( 136 GPa) and by 600-800 (±500) K at the inner core-outer core boundary ( 330 GPa), respectively. Our results indicate that Si has a relatively mild effect on the melting temperature of iron compared with S and O. Our thermodynamic modeling shows that Fe-5 wt% Ni alloyed with 6 wt% Si and 2 wt% S (which has a density-velocity profile that matches the outer core's seismic profile well) exhibits an adiabatic profile with temperatures of 3900 K and 5300 K at the top and bottom of the outer core, respectively. If Si is a major light element in the core, a geotherm modeled for the outer core indicates a thermal gradient of 5.8-6.8 (±1.6) K/km in the D″ region and a high heat flow of 13-19 TW across the core-mantle boundary.

Eukaryote-wide sequence analysis of mitochondrial β-barrel outer membrane proteins

PubMed Central

2011-01-01

Background The outer membranes of mitochondria are thought to be homologous to the outer membranes of Gram negative bacteria, which contain 100's of distinct families of β-barrel membrane proteins (BOMPs) often forming channels for transport of nutrients or drugs. However, only four families of mitochondrial BOMPs (MBOMPs) have been confirmed to date. Although estimates as high as 100 have been made in the past, the number of yet undiscovered MBOMPs is an open question. Fortunately, the recent discovery of a membrane integration signal (the β-signal) for MBOMPs gave us an opportunity to look for undiscovered MBOMPs. Results We present the results of a comprehensive survey of eukaryotic protein sequences intended to identify new MBOMPs. Our search employs recent results on β-signals as well as structural information and a novel BOMP predictor trained on both bacterial and mitochondrial BOMPs. Our principal finding is circumstantial evidence suggesting that few MBOMPs remain to be discovered, if one assumes that, like known MBOMPs, novel MBOMPs will be monomeric and β-signal dependent. In addition to this, our analysis of MBOMP homologs reveals some exceptions to the current model of the β-signal, but confirms its consistent presence in the C-terminal region of MBOMP proteins. We also report a β-signal independent search for MBOMPs against the yeast and Arabidopsis proteomes. We find no good candidates MBOMPs in yeast but the Arabidopsis results are less conclusive. Conclusions Our results suggest there are no remaining MBOMPs left to discover in yeast; and if one assumes all MBOMPs are β-signal dependent, few MBOMP families remain undiscovered in any sequenced organism. PMID:21272379

Targeting and assembly of components of the TOC protein import complex at the chloroplast outer envelope membrane

PubMed Central

Richardson, Lynn G. L.; Paila, Yamuna D.; Siman, Steven R.; Chen, Yi; Smith, Matthew D.; Schnell, Danny J.

2014-01-01

The translocon at the outer envelope membrane of chloroplasts (TOC) initiates the import of thousands of nuclear encoded preproteins required for chloroplast biogenesis and function. The multimeric TOC complex contains two GTP-regulated receptors, Toc34 and Toc159, which recognize the transit peptides of preproteins and initiate protein import through a β–barrel membrane channel, Toc75. Different isoforms of Toc34 and Toc159 assemble with Toc75 to form structurally and functionally diverse translocons, and the composition and levels of TOC translocons is required for the import of specific subsets of coordinately expressed proteins during plant growth and development. Consequently, the proper assembly of the TOC complexes is key to ensuring organelle homeostasis. This review will focus on our current knowledge of the targeting and assembly of TOC components to form functional translocons at the outer membrane. Our analyses reveal that the targeting of TOC components involves elements common to the targeting of other outer membrane proteins, but also include unique features that appear to have evolved to specifically facilitate assembly of the import apparatus. PMID:24966864

Targeting and assembly of components of the TOC protein import complex at the chloroplast outer envelope membrane.

PubMed

Richardson, Lynn G L; Paila, Yamuna D; Siman, Steven R; Chen, Yi; Smith, Matthew D; Schnell, Danny J

2014-01-01

The translocon at the outer envelope membrane of chloroplasts (TOC) initiates the import of thousands of nuclear encoded preproteins required for chloroplast biogenesis and function. The multimeric TOC complex contains two GTP-regulated receptors, Toc34 and Toc159, which recognize the transit peptides of preproteins and initiate protein import through a β-barrel membrane channel, Toc75. Different isoforms of Toc34 and Toc159 assemble with Toc75 to form structurally and functionally diverse translocons, and the composition and levels of TOC translocons is required for the import of specific subsets of coordinately expressed proteins during plant growth and development. Consequently, the proper assembly of the TOC complexes is key to ensuring organelle homeostasis. This review will focus on our current knowledge of the targeting and assembly of TOC components to form functional translocons at the outer membrane. Our analyses reveal that the targeting of TOC components involves elements common to the targeting of other outer membrane proteins, but also include unique features that appear to have evolved to specifically facilitate assembly of the import apparatus.

Assessment of undiscovered petroleum resources of the Amerasia Basin Petroleum Province

USGS Publications Warehouse

Houseknecht, David W.; Bird, Kenneth J.; Garrity, Christopher P.

2012-01-01

The Amerasia Basin Petroleum Province encompasses the Canada Basin and the sediment prisms along the Alaska and Canada margins, outboard from basinward margins (hingelines) of the rift shoulders that formed during extensional opening of the Canada Basin. The province includes the Mackenzie delta and slope, the outer shelves and marine slopes along the Arctic margins of Alaska and Canada, and the deep Canada Basin. The province is divided into four assessment units (AUs): (1) The Canning-Mackenzie deformed margin AU is that part of the rifted margin where the Brooks Range orogenic belt has overridden the rift shoulder and is deforming the rifted-margin prism of sediment outboard of the hingeline. This is the only part of the Amerasia Basin Province that has been explored and—even though more than 3 billion barrels of oil equivalent (BBOE) of oil, gas, and condensate have been discovered—none has been commercially produced. (2) The Alaska passive margin AU is the rifted-margin prism of sediment lying beneath the Beaufort outer shelf and slope that has not been deformed by tectonism. (3) The Canada passive margin AU is the rifted-margin prism of sediment lying beneath the Arctic outer shelf and slope (also known as the polar margin) of Canada that has not been deformed by tectonism. (4) The Canada Basin AU includes the sediment wedge that lies beneath the deep Canada Basin, north of the marine slope developed along the Alaska and Canada margins. Mean estimates of risked, undiscovered, technically recoverable resources include more than 6 billion barrels of oil (BBO), more than 19 trillion cubic feet (TCF) of associated gas, and more than 16 TCF of nonassociated gas in the Canning-Mackenzie deformed margin AU; about 1 BBO, about 3 TCF of associated gas, and about 3 TCF of nonassociated gas in the Alaska passive margin AU; and more than 2 BBO, about 7 TCF of associated gas, and about 8 TCF of nonassociated gas in the Canada passive margin AU. Quantities of natural gas liquids also are assessed in each AU. The Canada Basin AU was not quantitatively assessed because it is judged to hold less than 10 percent probability of containing at least one accumulation of 50 million barrels of oil equivalent.

Osmium-187 enrichment in some plumes: Evidence for core-mantle interaction?

USGS Publications Warehouse

Walker, R.J.; Morgan, J.W.; Horan, M.F.

1995-01-01

Calculations with data for asteroidal cores indicate that Earth's outer core may have a rhenium/osmium ratio at least 20 percent greater than that of the chondritic upper mantle, potentially leading to an outer core with an osmium-187/osmium-188 ratio at least 8 percent greater than that of chondrites. Because of the much greater abundance of osmium in the outer core relative to the mantle, even a small addition of metal to a plume ascending from the D??? layer would transfer the enriched isotopic signature to the mixture. Sources of certain plume-derived systems seem to have osmium-187/osmium-188 ratios 5 to 20 percent greater than that for chondrites, consistent with the ascent of a plume from the core-mantle boundary.

Physicochemical properties of kiwifruit starch.

PubMed

Li, Dongxing; Zhu, Fan

2017-04-01

Three varieties of golden kiwifruit (Actinidia chinensis) (Gold3, Gold9 and Hort16A) were collected at the commercial harvesting time, and physicochemical properties of starches from core and outer pericarp were studied. Starch contents (dry weight basis) in outer pericarp and core tissues ranged from 38.6 to 51.8% and 34.6 to 40.7%, respectively. All the kiwifruit starches showed B-type polymorph. Compared to the outer pericarp starches, amylose content and enzyme susceptibility of core starches were higher, and the degree of crystallinity, granule size and gelatinization parameters of core starches were somewhat lower. This suggests different biosynthetic properties between these two starches. The enthalpy changes of gelatinization of outer pericarp starches were high (∼21J/g). Rheological properties of outer pericarp starches were compared with normal maize and potato starches showed high yield stress of flow properties. This study revealed the unique properties of kiwifruit starch among various types of starches. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structural adaptations of proteins to different biological membranes

PubMed Central

Pogozheva, Irina D.; Tristram-Nagle, Stephanie; Mosberg, Henry I.; Lomize, Andrei L.

2013-01-01

To gain insight into adaptations of proteins to their membranes, intrinsic hydrophobic thicknesses, distributions of different chemical groups and profiles of hydrogen-bonding capacities (α and β) and the dipolarity/polarizability parameter (π*) were calculated for lipid-facing surfaces of 460 integral α-helical, β-barrel and peripheral proteins from eight types of biomembranes. For comparison, polarity profiles were also calculated for ten artificial lipid bilayers that have been previously studied by neutron and X-ray scattering. Estimated hydrophobic thicknesses are 30-31 Å for proteins from endoplasmic reticulum, thylakoid, and various bacterial plasma membranes, but differ for proteins from outer bacterial, inner mitochondrial and eukaryotic plasma membranes (23.9, 28.6 and 33.5 Å, respectively). Protein and lipid polarity parameters abruptly change in the lipid carbonyl zone that matches the calculated hydrophobic boundaries. Maxima of positively charged protein groups correspond to the location of lipid phosphates at 20-22 Å distances from the membrane center. Locations of Tyr atoms coincide with hydrophobic boundaries, while distributions maxima of Trp rings are shifted by 3-4 Å toward the membrane center. Distributions of Trp atoms indicate the presence of two 5-8 Å-wide midpolar regions with intermediate π* values within the hydrocarbon core, whose size and symmetry depend on the lipid composition of membrane leaflets. Midpolar regions are especially asymmetric in outer bacterial membranes and cell membranes of mesophilic but not hyperthermophilic archaebacteria, indicating the larger width of the central nonpolar region in the later case. In artificial lipid bilayers, midpolar regions are observed up to the level of acyl chain double bonds. PMID:23811361

An oilspill risk analysis for the Beaufort Sea, Alaska (proposed sale 71)outer continental shelf lease area

USGS Publications Warehouse

Samuels, W.B.; Hopkins, Dorothy; Lanfear, K.J.

1981-01-01

An oilspill risk analysis was conducted to determine the relative environmental hazards of developing oil in different regions of the Beaufort Sea, Alaska, (Proposed Sale 71) Outer Continental Shelf (OCS) lease area. The probability of spill occurrences, likely movement of oil slicks, and locations of resources vulnerable to spilled oil were analyzed. The model predicted movement of the center of spill mass and estimated the times between spill occurrence and contact with various resources, to allow a qualitative assessment of oil characteristics at the time of contact; no direct computation was made of weathering and cleanup. The model also assumed that any oil spilled under ice would remain in place, unchanged, until spring breakup. Ice movements, or travel of oil under ice, if occurring, would affect the results in a manner not directly predictable at this time. The combined results of spill occurrence and spill movement predictions yielded estimates of the overall risks associated with development of the proposed lease area. Assuming that oil exists in the lease area (a 99.3-percent chance) it is estimated that the leasing of the tracts proposed for OCS Sale 71 will result in an expected 9.2 oilspills (of 1,000 barrels or larger) over the lease lifetime of 25 years. This estimate is based on historic oilspill accident data for platforms and pipelines on the U.S. OCS (Gulf of Mexico and California). The estimated probability that land will be contacted by one or more oilspills (of 1,000 barrels or larger) that have been at sea less than 30 days (not counting any time trapped under ice) is greater than 99.5 percent. If oilspill accident data for Prudhoe Bay, Alaska, is used in the analysis, it is estimated that 5.6 oilspills (1,000 barrels or larger) will occur over the lease lifetime. The estimated probability that one or more oilspills (1,000 barrels or larger)will occur and contact land is99 percent. The results of a recent experimental cleanup operation for oilspills under ice in Canadian Arctic waters showed a substantial degree of success; this should be considered in evaluating impacts of spills predicted by this model. Oilspill occurrence probabilities are high primarily because of the large amount of oil believed to be present in the area.

Si-depleted outer core inferred from sound velocity measurements of liquid Fe-Si alloys

NASA Astrophysics Data System (ADS)

Nakajima, Y.; Imada, S.; Hirose, K.; Kuwayama, Y.; Sinmyo, R.; Tateno, S.; Ozawa, H.; Tsutsui, S.; Uchiyama, H.; Baron, A. Q. R.

2016-12-01

Recent core formation models [1,2] suggested that a large amount of Si could have been incorporated into the core forming metals in the early stage of the Earth. These studies gave estimates for the Si content in the core, from 2 to 9 wt.%. In order to constrain the Si content of the outer core, we have determined the sound wave velocity of liquid Fe-Si alloys under high pressures and high temperatures. Starting materials of Fe-Si alloys with 6.5 and 9 wt.% Si were melted in a laser-heated diamond-anvil cell. The longitudinal acoustic phonon excitation of a liquid metal was measured up to 52 GPa and 3200 K by using high resolution inelastic X-ray scattering spectroscopy at beamline BL35XU [3] of the SPring-8 synchrotron facility. Our results show that silicon significantly increases the P-wave velocity of liquid Fe. Seismological observation shows that the P-wave velocity in the outer core is 3-4% faster than in pure iron. Comparing the present results with seismological observations, the silicon content of the outer core should be limited to be <2 wt.%, significantly lower than previous estimates based on the element partitioning between core forming mental and silicate magma ocean during core formation processes. This indicates that the present-day core is depleted in Si relative to the ancient core just after core formation, which agrees with the recent proposal [4] that the Si content in the outer core has been diminished by SiO2 crystallization through the core cooling history. [1] Rubie et al. (2011) Earth Planet. Sci. Lett. 301, 31-42. [2] Siebert et al. (2013) Science 339, 1194-1197. [3] Baron et al. (2000) J. Phys. Chem. Solids 61, 461-465 [4] Hirose et al. (2015) Abstract presented at AGU Fall Meeting 2015.

Gravitational Core-Mantle Coupling and the Acceleration of the Earth

NASA Technical Reports Server (NTRS)

Rubincam, David Parry; Smith, David E. (Technical Monitor)

2001-01-01

Gravitational core-mantle coupling may be the cause of the observed variable acceleration of the Earth's rotation on the 1000 year timescale. The idea is that density inhomogeneities which randomly come and go in the liquid outer core gravitationally attract density inhomogeneities in the mantle and crust, torquing the mantle and changing its rotation state. The corresponding torque by the mantle on the core may also explain the westward drift of the magnetic field of 0.2 deg per year. Gravitational core-mantle coupling would stochastically affect the rate of change of the Earth's obliquity by just a few per cent. Its contribution to polar wander would only be about 0.5% the presently observed rate. Tidal friction is slowing down the rotation of the Earth, overwhelming a smaller positive acceleration from postglacial rebound. Coupling between the liquid outer core of the Earth and the mantle has long been a suspected reason for changes in the length-of-day. The present investigation focuses on the gravitational coupling between the density anomalies in the convecting liquid outer core and those in the mantle and crust as a possible cause for the observed nonsecular acceleration on the millenial timescale. The basic idea is as follows. There are density inhomogeneities caused by blobs circulating in the outer core like the blobs in a lava lamp; thus the outer core's gravitational field is not featureless. Moreover, these blobs will form and dissipate somewhat randomly. Thus there will be a time variability to the fields. These density inhomogeneities will gravitationally attract the density anomalies in the mantle.

Multimode optical fiber

DOEpatents

Bigot-Astruc, Marianne; Molin, Denis; Sillard, Pierre

2014-11-04

A depressed graded-index multimode optical fiber includes a central core, an inner depressed cladding, a depressed trench, an outer depressed cladding, and an outer cladding. The central core has an alpha-index profile. The depressed claddings limit the impact of leaky modes on optical-fiber performance characteristics (e.g., bandwidth, core size, and/or numerical aperture).

Laminated electromagnetic pump stator core

DOEpatents

Fanning, Alan W.

1995-01-01

A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference.

In vitro assembly of the outer core of the lipopolysaccharide from Escherichia coli K-12 and Salmonella typhimurium.

PubMed

Qian, Jinghua; Garrett, Teresa A; Raetz, Christian R H

2014-03-04

There are five distinct core structures in the lipopolysaccharides of Escherichia coli and at least two in Salmonella isolates, which vary principally in the outer core oligosaccharide. Six outer core glycosyltransferases, E. coli K-12 WaaG, WaaB, and WaaO and Salmonella typhimurium WaaI, WaaJ, and WaaK, were cloned, overexpressed, and purified. A novel substrate for WaaG was isolated from ΔwaaG E. coli overexpressing the lipid A phosphatase lpxE and the lipid A late acyltransferase lpxM. The action of lpxE and lpxM in the ΔwaaG background yielded heptose2-1-dephospho Kdo2-lipid A, a 1-dephosphorylated hexa-acylated lipid A with the inner core sugars that is easily isolated by organic extraction. Using this structurally defined acceptor and commercially available sugar nucleotides, each outer core glycosyltransferases was assayed in vitro. We show that WaaG and WaaB add a glucose and galactose sequentially to heptose2-1-dephospho Kdo2-lipid A. E. coli K-12 WaaO and S. typhimurium WaaI add a galactose to the WaaG/WaaB product but can also add a galactose to the WaaG product directly without the branched core sugar added by WaaB. Both WaaI and WaaO require divalent metal ions for optimal activity; however, WaaO, unlike WaaI, can add several glucose residues to its lipid acceptor. Using the product of WaaG, WaaB, and WaaI, we show that S. typhimurium WaaJ and WaaK transfer a glucose and N-acetylglucosamine, respectively, to yield the full outer core. This is the first demonstration of the in vitro assembly of the outer core of the lipopolysaccharide using defined lipid A-oligosaccharide acceptors and sugar donors.

In Vitro Assembly of the Outer Core of the Lipopolysaccharide from Escherichia coli K-12 and Salmonella typhimurium

PubMed Central

2015-01-01

There are five distinct core structures in the lipopolysaccharides of Escherichia coli and at least two in Salmonella isolates, which vary principally in the outer core oligosaccharide. Six outer core glycosyltransferases, E. coli K-12 WaaG, WaaB, and WaaO and Salmonella typhimurium WaaI, WaaJ, and WaaK, were cloned, overexpressed, and purified. A novel substrate for WaaG was isolated from ΔwaaG E. coli overexpressing the lipid A phosphatase lpxE and the lipid A late acyltransferase lpxM. The action of lpxE and lpxM in the ΔwaaG background yielded heptose2-1-dephospho Kdo2-lipid A, a 1-dephosphorylated hexa-acylated lipid A with the inner core sugars that is easily isolated by organic extraction. Using this structurally defined acceptor and commercially available sugar nucleotides, each outer core glycosyltransferases was assayed in vitro. We show that WaaG and WaaB add a glucose and galactose sequentially to heptose2-1-dephospho Kdo2-lipid A. E. coli K-12 WaaO and S. typhimurium WaaI add a galactose to the WaaG/WaaB product but can also add a galactose to the WaaG product directly without the branched core sugar added by WaaB. Both WaaI and WaaO require divalent metal ions for optimal activity; however, WaaO, unlike WaaI, can add several glucose residues to its lipid acceptor. Using the product of WaaG, WaaB, and WaaI, we show that S. typhimurium WaaJ and WaaK transfer a glucose and N-acetylglucosamine, respectively, to yield the full outer core. This is the first demonstration of the in vitro assembly of the outer core of the lipopolysaccharide using defined lipid A-oligosaccharide acceptors and sugar donors. PMID:24479701

FIELD SAMPLING OF RESIDUAL AVIATION GASOLINE IN SANDY SOIL

EPA Science Inventory

Two complimentary field sampling methods for the determination of residual aviation gasoline content in the contaminated capillary fringe of a fine, uniform, sandy soil were investigated. The first method featured filed extrusion of core barrels into pint size Mason jars, while ...

Functional implications of an intermeshing cogwheel-like interaction between TolC and MacA in the action of macrolide-specific efflux pump MacAB-TolC.

PubMed

Xu, Yongbin; Song, Saemee; Moeller, Arne; Kim, Nahee; Piao, Shunfu; Sim, Se-Hoon; Kang, Mooseok; Yu, Wookyung; Cho, Hyun-Soo; Chang, Iksoo; Lee, Kangseok; Ha, Nam-Chul

2011-04-15

Macrolide-specific efflux pump MacAB-TolC has been identified in diverse gram-negative bacteria including Escherichia coli. The inner membrane transporter MacB requires the outer membrane factor TolC and the periplasmic adaptor protein MacA to form a functional tripartite complex. In this study, we used a chimeric protein containing the tip region of the TolC α-barrel to investigate the role of the TolC α-barrel tip region with regard to its interaction with MacA. The chimeric protein formed a stable complex with MacA, and the complex formation was abolished by substitution at the functionally essential residues located at the MacA α-helical tip region. Electron microscopic study delineated that this complex was made by tip-to-tip interaction between the tip regions of the α-barrels of TolC and MacA, which correlated well with the TolC and MacA complex calculated by molecular dynamics. Taken together, our results demonstrate that the MacA hexamer interacts with TolC in a tip-to-tip manner, and implies the manner by which MacA induces opening of the TolC channel.

Functional Implications of an Intermeshing Cogwheel-like Interaction between TolC and MacA in the Action of Macrolide-specific Efflux Pump MacAB-TolC*

PubMed Central

Xu, Yongbin; Song, Saemee; Moeller, Arne; Kim, Nahee; Piao, Shunfu; Sim, Se-Hoon; Kang, Mooseok; Yu, Wookyung; Cho, Hyun-Soo; Chang, Iksoo; Lee, Kangseok; Ha, Nam-Chul

2011-01-01

Macrolide-specific efflux pump MacAB-TolC has been identified in diverse Gram-negative bacteria including Escherichia coli. The inner membrane transporter MacB requires the outer membrane factor TolC and the periplasmic adaptor protein MacA to form a functional tripartite complex. In this study, we used a chimeric protein containing the tip region of the TolC α-barrel to investigate the role of the TolC α-barrel tip region with regard to its interaction with MacA. The chimeric protein formed a stable complex with MacA, and the complex formation was abolished by substitution at the functionally essential residues located at the MacA α-helical tip region. Electron microscopic study delineated that this complex was made by tip-to-tip interaction between the tip regions of the α-barrels of TolC and MacA, which correlated well with the TolC and MacA complex calculated by molecular dynamics. Taken together, our results demonstrate that the MacA hexamer interacts with TolC in a tip-to-tip manner, and implies the manner by which MacA induces opening of the TolC channel. PMID:21325274

Influence of the surrounding environment in re-naturalized β-barrel membrane proteins.

PubMed

Lopes-Rodrigues, Maximilien; Triguero, Jordi; Torras, Juan; Perpète, Eric A; Michaux, Catherine; Zanuy, David; Alemán, Carlos

2018-03-01

Outer-membrane porins are currently being used to prepare bioinspired nanomembranes for selective ion transport by immobilizing them into polymeric matrices. However, the fabrication of these protein-integrated devices has been found to be strongly influenced by the instability of the β-barrel porin structure, which depends on surrounding environment. In this work, molecular dynamics simulations have been used to investigate the structural stability of a representative porin, OmpF, in three different environments: (i) aqueous solution at pH=7; (ii) a solution of neutral detergent in a concentration similar to the critical micelle concentration; and (iii) the protein embedded into a neutral detergent bilayer. The results indicate that the surrounding environment not only alters the stability of the β-barrel but affects the internal loop responsible of the ions transport, as well as the tendency of the porin proteins to aggregate into trimers. The detergent bilayer preserves the structure of OmpF protein as is found bacteria membranes, while pure aqueous solution induces a strong destabilization of the protein. An intermediate situation occurs for detergent solution. Our results have been rationalized in terms of protein⋯water and protein⋯detergent interactions, which makes them extremely useful for the future design of new generation of bioinspired protein-integrated devices. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization of polymer chain fractions of kiwifruit starch.

PubMed

Li, Dongxing; Zhu, Fan

2018-02-01

In this report, the amylose composition and molecular structure of starches from the core and outer pericarp of 3 golden kiwifruit varieties were characterised, using enzymatic and chromatographic techniques. Starches from the core tissues of kiwifruit tend to have higher amylose contents (by ∼3-5%) and longer unit chains of both amylopectins and their φ, β-limit dextrins (LDs) than those of the outer pericarp starches. The contents of short B-chains of the φ, β-LDs of amylopectins from the outer pericarp were higher (by ∼3%) than those of φ, β-LDs of the core amylopectins. Overall, the composition and structure of starches from the outer pericarp and core tissues of a golden kiwifruit were different. This study provides a structural basis to further investigate the starch degradation in kiwifruit, which may be of importance for the storage and eating quality of the fruit. Copyright © 2017 Elsevier Ltd. All rights reserved.

Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel: Comparison of In- and Out-of-Autoclave Facesheet Configurations

NASA Technical Reports Server (NTRS)

Pineda, Evan Jorge; Myers, David E.; Kosareo, Daniel N.; Zalewski, Bart F.; Kellas, Sotiris; Dixon, Genevieve D.; Krivanek, Thomas M.; Gyekenyesi, Thomas G.

2014-01-01

Four honeycomb sandwich panels, representing 1/16th arc segments of a 10-m diameter barrel section of the Heavy Lift Launch Vehicle, were manufactured and tested under the NASA Composites for Exploration and the NASA Constellation Ares V programs. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.0 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: in-autoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3 ft. by 5 ft. panels were cut from the 1/16th barrel sections and tested under compressive loading. Furthermore, linear eigenvalue and geometrically nonlinear finite element analyses were performed to predict the compressive response of each 3 ft. by 5 ft. panel. To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yielded good qualitative and quantitative predictions. Additionally, it was correctly predicted that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber angle misalignments, and three-dimensional effects on the compressive response of the panel.

Neutron shielding panels for reactor pressure vessels

DOEpatents

Singleton, Norman R [Murrysville, PA

2011-11-22

In a nuclear reactor neutron panels varying in thickness in the circumferential direction are disposed at spaced circumferential locations around the reactor core so that the greatest radial thickness is at the point of highest fluence with lesser thicknesses at adjacent locations where the fluence level is lower. The neutron panels are disposed between the core barrel and the interior of the reactor vessel to maintain radiation exposure to the vessel within acceptable limits.

The core paradox.

NASA Technical Reports Server (NTRS)

Kennedy, G. C.; Higgins, G. H.

1973-01-01

Rebuttal of suggestions from various critics attempting to provide an escape from the seeming paradox originated by Higgins and Kennedy's (1971) proposed possibility that the liquid in the outer core was thermally stably stratified and that this stratification might prove a powerful inhibitor to circulation of the outer core fluid of the kind postulated for the generation of the earth's magnetic field. These suggestions are examined and shown to provide no reasonable escape from the core paradox.

Inner Core Rotation from Geomagnetic Westward Drift and a Stationary Spherical Vortex in Earth's Core

NASA Technical Reports Server (NTRS)

Voorhies, Coerte V.

1998-01-01

The idea that geomagnetic westward drift indicates convective leveling of the planetary momentum gradient within Earth's core is pursued in search of a differentially rotating mean state, upon which various oscillations and secular effects might be superimposed. The desired state conforms to roughly spherical boundary conditions, minimizes dissipative interference with convective cooling in the bulk of the core, yet may aid core cooling by depositing heat in the uppermost core and lower mantle. The variational calculus of stationary dissipation applied to a spherical vortex within the core yields an interesting differential rotation profile, akin to spherical Couette flow bounded by thin Hartmann layers. Four boundary conditions are required. To concentrate shear induced dissipation near the core-mantle boundary, these are taken to be: (i) no-slip at the core-mantle interface; (ii) geomagnetically estimated bulk westward flow at the base of the core-mantle boundary layer; (iii) no-slip at the inner-outer core interface; and, to describe magnetic locking of the inner core to the deep outer core; (iv) hydrodynamically stress-free at the inner-outer core boundary. By boldly assuming the axial core angular momentum anomaly to be zero, the super-rotation of the inner core relative to the mantle is calculated to be at most 1.5 deg./yr.

Inner Core Rotation from Geomagnetic Westward Drift and a Stationary Spherical Vortex in Earth's Core

NASA Technical Reports Server (NTRS)

Voorhies, C. V.

1999-01-01

The idea that geomagnetic westward drift indicates convective leveling of the planetary momentum gradient within Earth's core is pursued in search of a differentially rotating mean state, upon which various oscillations and secular effects might be superimposed. The desired state conforms to roughly spherical boundary conditions, minimizes dissipative interference with convective cooling in the bulk of the core, yet may aide core cooling by depositing heat in the uppermost core and lower mantle. The variational calculus of stationary dissipation applied to a spherical vortex within the core yields an interesting differential rotation profile akin to spherical Couette flow bounded by thin Hartmann layers. Four boundary conditions are required. To concentrate shear induced dissipation near the core-mantle boundary, these are taken to be: (i) no-slip at the core-mantle interface; (ii) geomagnetically estimated bulk westward flow at the base of the core-mantle boundary layer; (iii) no-slip at the inner-outer core interface; and, to describe magnetic locking of the inner core to the deep outer core, (iv) hydrodynamically stress-free at the inner-outer core boundary. By boldly assuming the axial core angular momentum anomaly to be zero, the super-rotation of the inner core is calculated to be at most 1.5 degrees per year.

The periplasmic domain of Escherichia coli outer membrane protein A can undergo a localized temperature dependent structural transition.

PubMed

Ishida, Hiroaki; Garcia-Herrero, Alicia; Vogel, Hans J

2014-12-01

Gram-negative bacteria such as Escherichia coli are surrounded by two membranes with a thin peptidoglycan (PG)-layer located in between them in the periplasmic space. The outer membrane protein A (OmpA) is a 325-residue protein and it is the major protein component of the outer membrane of E. coli. Previous structure determinations have focused on the N-terminal fragment (residues 1-171) of OmpA, which forms an eight stranded transmembrane β-barrel in the outer membrane. Consequently it was suggested that OmpA is composed of two independently folded domains in which the N-terminal β-barrel traverses the outer membrane and the C-terminal domain (residues 180-325) adopts a folded structure in the periplasmic space. However, some reports have proposed that full-length OmpA can instead refold in a temperature dependent manner into a single domain forming a larger transmembrane pore. Here, we have determined the NMR solution structure of the C-terminal periplasmic domain of E. coli OmpA (OmpA(180-325)). Our structure reveals that the C-terminal domain folds independently into a stable globular structure that is homologous to the previously reported PG-associated domain of Neisseria meningitides RmpM. Our results lend credence to the two domain structure model and a PG-binding function for OmpA, and we could indeed localize the PG-binding site on the protein through NMR chemical shift perturbation experiments. On the other hand, we found no evidence for binding of OmpA(180-325) with the TonB protein. In addition, we have also expressed and purified full-length OmpA (OmpA(1-325)) to study the structure of the full-length protein in micelles and nanodiscs by NMR spectroscopy. In both membrane mimetic environments, the recombinant OmpA maintains its two domain structure that is connected through a flexible linker. A series of temperature-dependent HSQC experiments and relaxation dispersion NMR experiments detected structural destabilization in the bulge region of the periplasmic domain of OmpA above physiological temperatures, which may induce dimerization and play a role in triggering the previously reported larger pore formation. Copyright © 2014 Elsevier B.V. All rights reserved.

Constraints on The Coupled Thermal Evolution of the Earth's Core and Mantle, The Age of The Inner Core, And The Origin of the 186Os/188Os Core(?) Signal in Plume-Derived Lavas

NASA Astrophysics Data System (ADS)

Lassiter, J. C.

2005-12-01

Thermal and chemical interaction between the core and mantle has played a critical role in the thermal and chemical evolution of the Earth's interior. Outer core convection is driven by core cooling and inner core crystallization. Core/mantle heat transfer also buffers mantle potential temperature, resulting in slower rates of mantle cooling (~50-100 K/Ga) than would be predicted from the discrepancy between current rates of surface heat loss (~44 TW) and internal radioactive heat production (~20 TW). Core/mantle heat transfer may also generate thermal mantle plumes responsible for ocean island volcanic chains such as the Hawaiian Islands. Several studies suggest that mantle plumes, in addition to transporting heat from the core/mantle boundary, also carry a chemical signature of core/mantle interaction. Elevated 186Os/188Os ratios in lavas from Hawaii, Gorgona, and in the 2.8 Ga Kostomuksha komatiites have been interpreted as reflecting incorporation of an outer core component with high time-integrated Pt/Os and Re/Os ( Brandon et al., 1999, 2003; Puchtel et al., 2005). Preferential partitioning of Os relative to Re and Pt into the inner core during inner core growth may generate elevated Re/Os and Pt/Os ratios in the residual outer core. Because of the long half-life of 190Pt (the parent of 186Os, t1/2 = 489 Ga), an elevated 186Os/188Os outer core signature in plume lavas requires that inner core crystallization began early in Earth history, most likely prior to 3.5 Ga. This in turn requires low time-averaged core/mantle heat flow (<~2.5 TW) or large quantities of heat-producing elements in the core. Core/mantle heat flow may be estimated using boundary-layer theory, by measuring the heat transported in mantle plumes, by estimating the heat transported along the outer core adiabat, or by comparing the rates of heat production, surface heat loss, and secular cooling of the mantle. All of these independent methods suggest time-averaged core/mantle heat flow of ~5-14 TW. In the absence of heat-producing elements in the core, such high heat flow rates require an inner core younger than ~1 Ga and preclude the development of significant 186Os enrichment in the outer core. Experimental studies suggest that potassium may partition into Fe-S-O liquids during core formation. Radioactive decay of potassium in the core could provide an additional heat source and reconcile geophysical evidence for high core/mantle heat flow with apparent geochemical evidence for an ancient inner core. However, high concentrations of chalcophile elements such as Cu in the mantle are inconsistent with significant segregation of a S-rich liquid during core formation, precluding K partitioning into the core by this mechanism. Furthermore, core formation scenarios that would lead to high K content in the core (e.g., core formation prior to terrestrial volatile depletion) also result in high core Pb concentrations. Core/mantle interaction would then produce strong negative correlations between 186Os/188Os and 207Pb/204Pb ratios, but such correlations are not observed. In summary, elevated 186Os/188Os ratios in some plume-derived lavas are unlikely to reflect core/mantle interaction because the inner core is too young for this isotopic signature to have developed in the outer core. Melt generation from pyroxenite or fractionation of PGEs between sulfide melts and monosulfide solid solutions provide alternative mechanisms for generating ancient mantle reservoirs with elevated Pt/Os and 186Os/188Os.

Plasma current start-up by the outer ohmic heating coils in the Saskatchewan TORus Modified (STOR-M) iron core tokamak

DOE PAGES

Mitarai, O.; Xiao, C.; McColl, D.; ...

2015-03-24

A plasma current up to 15 kA has been driven with outer ohmic heating (OH) coils in the STOR-M iron core tokamak. Even when the inner OH coil is disconnected, the outer OH coils alone can induce the plasma current as primary windings and initial breakdown are even easier in this coil layout. Our results suggest a possibility to use an iron core in a spherical tokamak to start up the plasma current without a central solenoid. Finally, the effect of the iron core saturation on the extension of the discharge pulse length has been estimated for further experiments inmore » the STOR-M tokamak.« less

Plasma current start-up by the outer ohmic heating coils in the Saskatchewan TORus Modified (STOR-M) iron core tokamak

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

Mitarai, O.; Xiao, C.; McColl, D.

A plasma current up to 15 kA has been driven with outer ohmic heating (OH) coils in the STOR-M iron core tokamak. Even when the inner OH coil is disconnected, the outer OH coils alone can induce the plasma current as primary windings and initial breakdown are even easier in this coil layout. Our results suggest a possibility to use an iron core in a spherical tokamak to start up the plasma current without a central solenoid. Finally, the effect of the iron core saturation on the extension of the discharge pulse length has been estimated for further experiments inmore » the STOR-M tokamak.« less

Seismic Velocity Anomalies in the Outer Core: The Final Frontier

NASA Astrophysics Data System (ADS)

Stevenson, D. J.

2008-12-01

Variation in density along outer core geoid surfaces must be very small (of order one part in a billion) since the resulting fluid motions and buoyancy fluxes would otherwise be prohibitively large for any reasonable choice of outer core viscosity. In any situation where seismic velocity variations are proportional to density variations (a generalized Birch's "law") this means that the resulting seismic travel time variations in the outer core would be unobservable. The largest lateral variations in the outer core are thus likely to arise from the distortion of geoid surfaces caused by density anomalies in the mantle or inner core. However, these do not change on decadal timescales and would be very difficult to separate from the inner core or mantle variations that cause them. Nonetheless, a recent study (Dai and Song, GRL, vol. 35, L16311, doi:10.1029/2008GL034895) provides evidence for time-variable outer core seismic velocity at the level of ten parts per million. Assuming this is real, I argue that the best candidate explanation is that all or part of the outer core is a two-phase medium consisting of a small mass fraction of small (ten or 100 micron-sized) particles of exsolving silicate material suspended in the convecting liquid. The seismic velocity of this two phase medium can vary at the desired level should the size distribution of particles vary from place to place (and with time) as one would expect in a convecting system, even though the mean density of the medium is invariant at the level of a part per billion, as required by dynamical considerations (thus invalidating Birch's "law"). The seismic velocity variation depends on the ratio of diffusion times to seismic periods, where the diffusion times are thermal or compositional for the particles or the particle spacing. This idea is not new (cf. Stevenson, JGR, 1983) but gains increased impetus from recent work on the nature of core formation and the desirability of an additional energy source for driving the geodynamo, as would arise if of order 10km of mantle underplating occurred over all of geologic time. The amount of suspended material will be tiny at any one time, illustrating the remarkable sensitivity of seismic waves to the microstructure of the medium. Consequences of this picture include some dissipation (finite Q) in the outer core and a significant frequency dependence of this effect, but precise predictions are difficult because of uncertainties in particle kinetics and convective velocities. The two-phase region may also influence radial seismic velocity profiles, particularly in the layers immediately adjacent to the boundaries (e.g., the layer just below the core-mantle boundary), an effect that has been suggested in the literature on many occasions. Even so, this explanation for lateral variability remains marginal at best, suggesting that the claimed observation is either not real or that some other explanation still awaits discovery.

Identification of outer membrane proteins with emulsifying activity by prediction of beta-barrel regions.

PubMed

Walzer, Gil; Rosenberg, Eugene; Ron, Eliora Z

2009-01-01

Microbial bioemulsifiers are secreted by many bacteria and are important for bacterial interactions with hydrophobic substrates or nutrients and for a variety of biotechnological applications. We have recently shown that the OmpA protein in several members of the Acinetobacter family has emulsifying properties. These properties of OmpA depend on the amino acid composition of four putative extra-membrane loops, which in various strains of Acinetobacter, but not in E. coli, are highly hydrophobic. As many Acinetobacter strains can utilize hydrophobic carbon sources, such as oil, the emulsifying activity of their OmpA may be important for the utilization and uptake of hydrocarbons. We assumed that if outer membrane proteins with emulsifying activity are physiologically important, they may exist in additional oil degrading bacteria. In order to identify such proteins, it was necessary to obtain bioinformatics-based predictions for hydrophobic extra-membrane loops. Here we describe a method for using protein sequence data for predicting the hydrophobic properties of the extra-membrane loops of outer membrane proteins. The feasibility of this method is demonstrated by its use to identify a new microbial bioemulsifier - OprG - an outer membrane protein of the oil degrading Pseudomonas putida KT2440.

LppX is a lipoprotein required for the translocation of phthiocerol dimycocerosates to the surface of Mycobacterium tuberculosis

PubMed Central

Sulzenbacher, Gerlind; Canaan, Stéphane; Bordat, Yann; Neyrolles, Olivier; Stadthagen, Gustavo; Roig-Zamboni, Véronique; Rauzier, Jean; Maurin, Damien; Laval, Françoise; Daffé, Mamadou; Cambillau, Christian; Gicquel, Brigitte; Bourne, Yves; Jackson, Mary

2006-01-01

Cell envelope lipids play an important role in the pathogenicity of mycobacteria, but the mechanisms by which they are transported to the outer membrane of these prokaryotes are largely unknown. Here, we provide evidence that LppX is a lipoprotein required for the translocation of complex lipids, the phthiocerol dimycocerosates (DIM), to the outer membrane of Mycobacterium tuberculosis. Abolition of DIM transport following disruption of the lppX gene is accompanied by an important attenuation of the virulence of the tubercle bacillus. The crystal structure of LppX unveils an U-shaped β-half-barrel dominated by a large hydrophobic cavity suitable to accommodate a single DIM molecule. LppX shares a similar fold with the periplasmic molecular chaperone LolA and the outer membrane lipoprotein LolB, which are involved in the localization of lipoproteins to the outer membrane of Gram-negative bacteria. Based on the structure and although an indirect participation of LppX in DIM transport cannot yet be ruled out, we propose LppX to be the first characterized member of a family of structurally related lipoproteins that carry lipophilic molecules across the mycobacterial cell envelope. PMID:16541102

Laminated electromagnetic pump stator core

DOEpatents

Fanning, A.W.

1995-08-08

A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference. This pump is used in nuclear fission reactors. 19 figs.

Models of the Earth's Core.

PubMed

Stevenson, D J

1981-11-06

Combined inferences from seismology, high-pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to models of the earth's core with the following properties. Core formation was contemporaneous with earth accretion; the core is not in chemical equilibrium with the mantle; the outer core is a fluid iron alloy containing significant quantities of lighter elements and is probably almost adiabatic and compositionally uniform; the more iron-rich inner solid core is a consequence of partial freezing of the outer core, and the energy release from this process sustains the earth's magnetic field; and the thermodynamic properties of the core are well constrained by the application of liquid-state theory to seismic and laboratory data.

Design of 8-ft-Diameter Barrel Test Article Attachment Rings for Shell Buckling Knockdown Factor Project

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.; Hilburger, Mark W.

2010-01-01

The Shell Buckling Knockdown Factor (SBKF) project includes the testing of sub-scale cylinders to validate new shell buckling knockdown factors for use in the design of the Ares-I and Ares-V launch vehicles. Test article cylinders represent various barrel segments of the Ares-I and Ares-V vehicles, and also include checkout test articles. Testing will be conducted at Marshall Space Flight Center (MSFC) for test articles having an eight-foot diameter outer mold line (OML) and having lengths that range from three to ten feet long. Both ends of the test articles will be connected to the test apparatus using attachment rings. Three multiple-piece and one single-piece design for the attachment rings were developed and analyzed. The single-piece design was chosen and will be fabricated from either steel or aluminum (Al) depending on the required safety factors (SF) for test hardware. This report summarizes the design and analysis of these attachment ring concepts.

Concentric core optical fiber with multiple-mode signal transmission

DOEpatents

Muhs, J.D.

1997-05-06

A concentric core optical fiber provides for the simultaneous but independent transmission of signals over a single optical fiber. The concentric optical fiber is constructed of a single-mode or multimode inner optical fiber defined by a core and a cladding of a lower index of refraction than the core and an outer optical fiber defined by additional cladding concentrically disposed around the cladding and of an index of refraction lower than the first mentioned cladding whereby the latter functions as the core of the outer optical fiber. By employing such an optical fiber construction with a single-mode inner core or optical fiber, highly sensitive interferometric and stable less sensitive amplitude based sensors can be placed along the same length of a concentric core optical fiber. Also, by employing the concentric core optical fiber secure telecommunications can be achieved via the inner optical fiber since an intrusion of the concentric optical fiber will first cause a variation in the light being transmitted through the outer optical fiber and this variation of light being used to trigger a suitable alarm indicative of the intrusion. 3 figs.

Concentric core optical fiber with multiple-mode signal transmission

DOEpatents

Muhs, Jeffrey D.

1997-01-01

A concentric core optical fiber provides for the simultaneous but independent transmission of signals over a single optical fiber. The concentric optical fiber is constructed of a single-mode or multimode inner optical fiber defined by a core and a cladding of a lower index of refraction than the core and an outer optical fiber defined by additional cladding concentrically disposed around the cladding and of an index of refraction lower than the first mentioned cladding whereby the latter functions as the core of the outer optical fiber. By employing such an optical fiber construction with a single-mode inner core or optical fiber, highly sensitive interferometric and stable less sensitive amplitude based sensors can be placed along the same length of a concentric core optical fiber. Also, by employing the concentric core optical fiber secure telecommunications can be achieved via the inner optical fiber since an intrusion of the concentric optical fiber will first cause a variation in the light being transmitted through the outer optical fiber and this variation of light being used to trigger a suitable alarm indicative of the intrusion.

Delayed Geodynamo in Hadean

NASA Astrophysics Data System (ADS)

Arkani-Hamed, J.

2014-12-01

Paleointensity measurements of Archean rocks reveal a strong geodynamo at ~3.45 Ga, while excess nitrogen content of lunar soil samples implies no geodynamo at ~3.9 Ga. Here I propose that initiation of a strong geodynamo is delayed due to accretion style of Earth, involving collision and merging of a few dozen Moon to Mars size planetary embryos. Two accretion scenarios consisting of 25 and 50 embryos are investigated. The collision of an embryo heats the proto-Earth's core differentially and the rotating low-viscosity core stably stratifies, creating a spherically symmetric and radially increasing temperature distribution. Convection starts in the outer core after each impact but is destroyed by the next impact. The iron core of an impacting embryo descends in the mantle and merges to the proto-Earth's core. Both adiabatic and non-adiabatic merging cases are studied. A major part of the gravitational energy released due to core merging is used to lift up the upper portion of the core to emplace the impactor core material at the neutrally buoyant level in the proto-Earth's core. The remaining energy is converted to heat. In the adiabatic case the merging embryo's core retains all of the remaining energy, while in the non-adiabatic merging 50% of the remaining energy is shared with the outer part of the proto-Earth's core where the embryo's core descends. The two merging models result in significantly different temperature distributions in the core at the end of accretion. After the accretion, the convecting shell in the outer core grows monotonically and generates geodynamo gradually. It takes about 50-100 Myr for the convecting shell to generate a strong dipole field at the surface, 50,000 to 100,000 nT, in the presence of a large stably stratified liquid inner core when the convecting outer core thickness exceeds about one half the radius of the Earth's core.

Functional assay of Salmonella typhi OmpC using reconstituted large unilamellar vesicles: a general method for characterization of outer membrane proteins.

PubMed

Sundara Baalaji, N; Mathew, M K; Krishnaswamy, S

2006-10-01

The immunodominant trimeric beta-barrel outer membrane protein OmpC from Salmonella typhi, the causative agent of typhoid, has been functionally characterized here. The activity in the vesicle environment was studied in vitro using OmpC reconstituted into proteoliposomes. Passage of polysaccharides and polyethyleneglycols through OmpC has been examined to determine the permeability properties. The relative rate of neutral solute flux yields a radius of 1.1 nm for the S. typhi OmpC pore. This is almost double the pore size of Escherichia coli. This provides an example of large pore size present in the porins that form trimers as in the general bacterial porin family. The method used in this study provides a good membrane model for functional studies of porins.

Oil shale resources in the Eocene Green River Formation, Greater Green River Basin, Wyoming, Colorado, and Utah

USGS Publications Warehouse

,

2011-01-01

The U.S. Geological Survey (USGS) recently completed a comprehensive assessment of in-place oil in oil shales in the Eocene Green River in the Greater Green River Basin, Wyoming, Colorado, and Utah. This CD-ROM includes reports, data, and an ArcGIS project describing the assessment. A database was compiled that includes about 47,000 Fischer assays from 186 core holes and 240 rotary drill holes. Most of the oil yield data were analyzed by the former U.S. Bureau of Mines oil shale laboratory in Laramie, Wyoming, and some analyses were made by private laboratories. Location data for 971 Wyoming oil-shale drill holes are listed in a spreadsheet and included in the CD-ROM. Total in-place resources for the three assessed units in the Green River Formation are: (1) Tipton Shale Member, 362,816 million barrels of oil (MMBO), (2) Wilkins Peak Member, 704,991 MMBO, and (3) LaClede Bed of the Laney Member, 377,184 MMBO, for a total of 1.44 trillion barrels of oil in place. This compares with estimated in-place resources for the Piceance Basin of Colorado of 1.53 trillion barrels and estimated in-place resources for the Uinta Basin of Utah and Colorado of 1.32 trillion barrels.

Crystal Structures of Major Envelope Proteins VP26 and VP28 from White Spot Syndrome Virus Shed Light on Their Evolutionary Relationship

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

Tang,X.; Wu, J.; Sivaraman, J.

2007-01-01

White spot syndrome virus (WSSV) is a virulent pathogen known to infect various crustaceans. It has bacilliform morphology with a tail-like appendage at one end. The envelope consists of four major proteins. Envelope structural proteins play a crucial role in viral infection and are believed to be the first molecules to interact with the host. Here, we report the localization and crystal structure of major envelope proteins VP26 and VP28 from WSSV at resolutions of 2.2 and 2.0 {angstrom}, respectively. These two proteins alone account for approximately 60% of the envelope, and their structures represent the first two structural envelopemore » proteins of WSSV. Structural comparisons among VP26, VP28, and other viral proteins reveal an evolutionary relationship between WSSV envelope proteins and structural proteins from other viruses. Both proteins adopt {beta}-barrel architecture with a protruding N-terminal region. We have investigated the localization of VP26 and VP28 using immunoelectron microscopy. This study suggests that VP26 and VP28 are located on the outer surface of the virus and are observed as a surface protrusion in the WSSV envelope, and this is the first convincing observation for VP26. Based on our studies combined with the literature, we speculate that the predicted N-terminal transmembrane region of VP26 and VP28 may anchor on the viral envelope membrane, making the core {beta}-barrel protrude outside the envelope, possibly to interact with the host receptor or to fuse with the host cell membrane for effective transfer of the viral infection. Furthermore, it is tempting to extend this host interaction mode to other structural viral proteins of similar structures. Our finding has the potential to extend further toward drug and vaccine development against WSSV.« less

Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel. Part 3; 8-ply Out-of-Autoclave Facesheets

NASA Technical Reports Server (NTRS)

Pineda, Evan J.; Myers, David E.; Kosareo, Daniel N.; Kellas, Sotiris

2014-01-01

Four honeycomb sandwich panels, representing 1/16th arc segments of a 10 m diameter barrel section of the heavy lift launch vehicle, were manufactured under the NASA Composites for Exploration program and the NASA Constellation Ares V program. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.000 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: inautoclave IM7/977-3 and out-of-autoclave T40-800B/5320-1. Smaller 3- by 5-ft panels were cut from the 1/16th barrel sections. These panels were tested under compressive loading at the NASA Langley Research Center. Furthermore, linear eigenvalue and geometrically nonlinear finite element analyses were performed to predict the compressive response of the 3- by 5-ft panels. This manuscript summarizes the experimental and analytical modeling efforts pertaining to the panel composed of 8-ply, T40-800B/5320-1 facesheets (referred to as Panel C). To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear, two-dimensional (2-D) and three-dimensional (3-D), models yield good qualitative and quantitative predictions. Additionally, it was predicted correctly that the panel would fail in buckling prior to failing in strength.

The truth about laser fiber diameters.

PubMed

Kronenberg, Peter; Traxer, Olivier

2014-12-01

To measure the various diameters of laser fibers from various manufacturers and compare them with the advertised diameter. Fourteen different unused laser fibers from 6 leading manufacturers with advertised diameters of 200, 270, 272, 273, 365, and 400 μm were measured by light microscopy. The outer diameter (including the fiber coating, cladding, and core), cladding diameter (including the cladding and the fiber core), and core diameter were measured. Industry representatives of the manufacturers were interviewed about the diameter of their fibers. For all fibers, the outer and cladding diameters differed significantly from the advertised diameter (P <.00001). The outer diameter, which is of most practical relevance for urologists, exhibited a median increase of 87.3% (range, 50.7%-116.7%). The outer, cladding, and core diameters of fibers with equivalent advertised diameters differed by up to 180, 100, and 78 μm, respectively. Some 200-μm fibers had larger outer diameters than the 270- to 273-μm fibers. All packaging material and all laser fibers lacked clear and precise fiber diameter information labels. Of 12 representatives interviewed, 8, 3, and 1 considered the advertised diameter to be the outer, the cladding, and the core diameter, respectively. Representatives within the same company frequently gave different answers. This study suggests that, at present, there is a lack of uniformity between laser fiber manufacturers, and most of the information conveyed to urologists regarding laser fiber diameter may be incorrect. Because fibers larger than the advertised laser fibers are known to influence key interventional parameters, this misinformation can have surgical repercussions. Copyright © 2014 Elsevier Inc. All rights reserved.

Exchangeability of N termini in the ligand-gated porins of Escherichia coli.

PubMed

Scott, D C; Cao, Z; Qi, Z; Bauler, M; Igo, J D; Newton, S M; Klebba, P E

2001-04-20

The ferric siderophore transporters of the Gram-negative bacterial outer membrane manifest a unique architecture: Their N termini fold into a globular domain that lodges within, and physically obstructs, a transmembrane porin beta-barrel formed by their C termini. We exchanged and deleted the N termini of two such siderophore receptors, FepA and FhuA, which recognize and transport ferric enterobactin and ferrichrome, respectively. The resultant chimeric proteins and empty beta-barrels avidly bound appropriate ligands, including iron complexes, protein toxins, and viruses. Thus, the ability to recognize and discriminate these molecules fully originates in the transmembrane beta-barrel domain. Both the hybrid and the deletion proteins also transported the ferric siderophore that they bound. The FepA constructs showed less transport activity than wild type receptor protein, but the FhuA constructs functioned with turnover numbers that were equivalent to wild type. The mutant proteins displayed the full range of transport functionalities, despite their aberrant or missing N termini, confirming (Braun, M., Killmann, H., and Braun, V. (1999) Mol. Microbiol. 33, 1037-1049) that the globular domain within the pore is dispensable to the siderophore internalization reaction, and when present, acts without specificity during solute uptake. These and other data suggest a transport process in which siderophore receptors undergo multiple conformational states that ultimately expel the N terminus from the channel concomitant with solute internalization.

Small hydrogen/oxygen rocket flowfield behavior from heat flux measurements

NASA Technical Reports Server (NTRS)

Reed, Brian D.

1993-01-01

The mixing and heat transfer phenomena in small rocket flow fields with fuel film cooling is not well understood. An instrumented, water-cooled chamber with a gaseous hydrogen/gaseous oxygen injector was used to gather steady-state inner and outer wall temperature profiles. The chamber was tested at 414 kPa (60 psia) chamber pressure, from mixture ratios of 3.41 to 8.36. Sixty percent of the fuel was used for film cooling. These temperature profiles were used as boundary conditions in a finite element analysis program, MSC/NASTRAN, to calculate the local radial and axial heat fluxes in the chamber wall. The normal heat fluxes were then calculated and used as a diagnostic of the rocket's flow field behavior. The normal heat fluxes determined were on the order of 1.0 to 3.0 MW/meters squared (0.6 to 1.8 Btu/sec-inches squared). In the cases where mixture ratio was 5 or above, there was a sharp local heat flux maximum in the barrel section of the chamber. This local maximum seems to indicate a reduction or breakdown of the fuel film cooling layer, possibly due to increased mixing in the shear layer between the film and core flows. However, the flow was thought to be completely laminar, as the throat Reynolds numbers were below 50,000 for all the cases. The increased mixing in the shear layer in the higher mixture ratio cases appeared not to be due to the transition of the flow from laminar to turbulent, but rather due to increased reactions between the hydrogen film and oxidizer-rich core flows.

Evaluating the Role and Effects of Precipitation on Relativistic Electron Losses during Storms

NASA Astrophysics Data System (ADS)

Chen, Y.; Fu, X.

2016-12-01

Theoretic studies have suggested that during storm times various waves (e.g., whistler-mode chorus and electromagnetic ion cyclotron waves) can cause significant precipitation of relativistic ( MeV) electrons that are originally trapped inside the outer radiation belt. However, the role of precipitation and its quantitative contribution to the losses of outer-belt electrons remain open questions. In this study, we tackle these questions by systemically examining the latest wave and electron in-situ, simultaneous observations made at different altitudes by Van Allen Probes from near equator, NOAA POES at low Earth orbits near/across electron loss cone, and BARREL under the mesosphere. After calibrating with DEMTER observations, we first confirm and quantify the response of POES MEPED proton channels to MeV electrons. Next, we identify a list of precipitation events from BARREL and POES measurements, examine the temporal adn spatial relation between the two data sets, and estimate the intensities of electron precipitation with ascertained uncertainties. Then, from Van Allen Probes data, we select another list of dropout events during storms. By cross checking the above two lists, we are able to determine the causal relation between precipitation and dropouts through individual case as well as statistical studies so as to quantify the contributions from precipitation. This study mainly focuses on the relatively small L-shells with positive phase space density radial gradient in order to alleviate the impacts from outward radial diffusion and adiabatic effects. Based upon the recent discovery of cross-energy cross-pitch angle coherence, we pay particular attention to the cross-term diffusions which may account for the extra "loss" needed by observed MeV electron dropouts. Results from this observational study will advance our knowledge on the loss mechanism of outer-belt electrons, and thus lay down another stepping stone towards high-fidelity physics-based models for radiation belts.

Distinctive Roles for Periplasmic Proteases in the Maintenance of Essential Outer Membrane Protein Assembly.

PubMed

Soltes, Garner R; Martin, Nicholas R; Park, Eunhae; Sutterlin, Holly A; Silhavy, Thomas J

2017-10-15

Outer membrane protein (OMP) biogenesis in Escherichia coli is a robust process essential to the life of the organism. It is catalyzed by the β-barrel assembly machine (Bam) complex, and a number of quality control factors, including periplasmic chaperones and proteases, maintain the integrity of this trafficking pathway. Little is known, however, about how periplasmic proteases recognize and degrade OMP substrates when assembly is compromised or whether different proteases recognize the same substrate at distinct points in the assembly pathway. In this work, we use well-defined assembly-defective mutants of LptD, the essential lipopolysaccharide assembly translocon, to show that the periplasmic protease DegP degrades substrates with assembly defects that prevent or impair initial contact with Bam, causing the mutant protein to accumulate in the periplasm. In contrast, another periplasmic protease, BepA, degrades a LptD mutant substrate that has engaged the Bam complex and formed a nearly complete barrel. Furthermore, we describe the role of the outer membrane lipoprotein YcaL, a protease of heretofore unknown function, in the degradation of a LptD substrate that has engaged the Bam complex but is stalled at an earlier step in the assembly process that is not accessible to BepA. Our results demonstrate that multiple periplasmic proteases monitor OMPs at distinct points in the assembly process. IMPORTANCE OMP assembly is catalyzed by the essential Bam complex and occurs in a cellular environment devoid of energy sources. Assembly intermediates that misfold can compromise this essential molecular machine. Here we demonstrate distinctive roles for three different periplasmic proteases that can clear OMP substrates with folding defects that compromise assembly at three different stages. These quality control factors help ensure the integrity of the permeability barrier that contributes to the intrinsic resistance of Gram-negative organisms to many antibiotics. Copyright © 2017 American Society for Microbiology.

Models of the earth's core

NASA Technical Reports Server (NTRS)

Stevenson, D. J.

1981-01-01

Combined inferences from seismology, high-pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to models of the earth's core with five basic properties. These are that core formation was contemporaneous with earth accretion; the core is not in chemical equilibrium with the mantle; the outer core is a fluid iron alloy containing significant quantities of lighter elements and is probably almost adiabatic and compositionally uniform; the more iron-rich inner solid core is a consequence of partial freezing of the outer core, and the energy release from this process sustains the earth's magnetic field; and the thermodynamic properties of the core are well constrained by the application of liquid-state theory to seismic and labroatory data.

Constraints on the Properties of the Moon's Outer Core from High-Pressure Sound Velocity Measurements on Fe-S Liquids

NASA Astrophysics Data System (ADS)

Jing, Z.; Wang, Y.; Kono, Y.; Yu, T.; Sakamaki, T.; Park, C.; Rivers, M. L.; Sutton, S. R.; Shen, G.

2013-12-01

Geophysical observations based on lunar seismology and laser ranging strongly suggest that the Moon's iron core is partially molten. Similar to Earth and other terrestrial planets, light elements, such as sulfur, silicon, carbon, and oxygen, are likely present in the lunar core. Determining the light element concentration in the outer core is of vital importance to the understanding of the structure, dynamics, and chemical evolution of the Moon, as well as the enigmatic history of the lunar dynamo. Among the candidate elements, sulfur is the preferred major light element in the lunar outer due to its high abundance in the parent bodies of iron meteorites, its high solubility in liquid Fe at the lunar core pressure (~5 GPa), and its strong effects on reducing the density, velocity, and freezing temperature of the core. In this study, we conducted in-situ sound velocity measurements on liquid samples of four different compositions, including pure Fe, Fe-10wt%S, Fe-20wt%S, and Fe-27wt%S, at pressure and temperature conditions up to 8 GPa and 1973 K (encompassing the entire lunar depth range), using the Kawai-type multi-anvil device at the GSECARS beamline 13-ID-D and the Paris-Edinburgh cell at HPCAT beamline 16-BM-B. Our results show that the velocity of Fe-rich liquids increases upon compression, decreases with increasing sulfur content, and is nearly independent of temperature. Compared to the seismic velocity of the outer core, our velocity data constrain the sulfur content at 4×2 wt%, indicating a significantly denser (6.4×0.4 g/cm3) and hotter (1860×60 K) outer core than previously estimated. A new lunar structure model incorporating available geophysical observations points to a smaller core radius. Our model also suggests a top-down solidification scenario for the evolution of the lunar core. Such an 'iron snow' process may have been an important mechanism for the growth of the inner core.

Excore Modeling with VERAShift

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

Pandya, Tara M.; Evans, Thomas M.

It is important to be able to accurately predict the neutron flux outside the immediate reactor core for a variety of safety and material analyses. Monte Carlo radiation transport calculations are required to produce the high fidelity excore responses. Under this milestone VERA (specifically the VERAShift package) has been extended to perform excore calculations by running radiation transport calculations with Shift. This package couples VERA-CS with Shift to perform excore tallies for multiple state points concurrently, with each component capable of parallel execution on independent domains. Specifically, this package performs fluence calculations in the core barrel and vessel, or, performsmore » the requested tallies in any user-defined excore regions. VERAShift takes advantage of the general geometry package in Shift. This gives VERAShift the flexibility to explicitly model features outside the core barrel, including detailed vessel models, detectors, and power plant details. A very limited set of experimental and numerical benchmarks is available for excore simulation comparison. The Consortium for the Advanced Simulation of Light Water Reactors (CASL) has developed a set of excore benchmark problems to include as part of the VERA-CS verification and validation (V&V) problems. The excore capability in VERAShift has been tested on small representative assembly problems, multiassembly problems, and quarter-core problems. VERAView has also been extended to visualize these vessel fluence results from VERAShift. Preliminary vessel fluence results for quarter-core multistate calculations look very promising. Further development is needed to determine the details relevant to excore simulations. Validation of VERA for fluence and excore detectors still needs to be performed against experimental and numerical results.« less

High-gradient compact linear accelerator

DOEpatents

Carder, B.M.

1998-05-26

A high-gradient linear accelerator comprises a solid-state stack in a vacuum of five sets of disc-shaped Blumlein modules each having a center hole through which particles are sequentially accelerated. Each Blumlein module is a sandwich of two outer conductive plates that bracket an inner conductive plate positioned between two dielectric plates with different thicknesses and dielectric constants. A third dielectric core in the shape of a hollow cylinder forms a casing down the series of center holes, and it has a dielectric constant different that the two dielectric plates that sandwich the inner conductive plate. In operation, all the inner conductive plates are charged to the same DC potential relative to the outer conductive plates. Next, all the inner conductive plates are simultaneously shorted to the outer conductive plates at the outer diameters. The signal short will propagate to the inner diameters at two different rates in each Blumlein module. A faster wave propagates quicker to the third dielectric core across the dielectric plates with the closer spacing and lower dielectric constant. When the faster wave reaches the inner extents of the outer and inner conductive plates, it reflects back outward and reverses the field in that segment of the dielectric core. All the field segments in the dielectric core are then in unipolar agreement until the slower wave finally propagates to the third dielectric core across the dielectric plates with the wider spacing and higher dielectric constant. During such unipolar agreement, particles in the core are accelerated with gradients that exceed twenty megavolts per meter. 10 figs.

High-gradient compact linear accelerator

DOEpatents

Carder, Bruce M.

1998-01-01

A high-gradient linear accelerator comprises a solid-state stack in a vacuum of five sets of disc-shaped Blumlein modules each having a center hole through which particles are sequentially accelerated. Each Blumlein module is a sandwich of two outer conductive plates that bracket an inner conductive plate positioned between two dielectric plates with different thicknesses and dielectric constants. A third dielectric core in the shape of a hollow cylinder forms a casing down the series of center holes, and it has a dielectric constant different that the two dielectric plates that sandwich the inner conductive plate. In operation, all the inner conductive plates are charged to the same DC potential relative to the outer conductive plates. Next, all the inner conductive plates are simultaneously shorted to the outer conductive plates at the outer diameters. The signal short will propagate to the inner diameters at two different rates in each Blumlein module. A faster wave propagates quicker to the third dielectric core across the dielectric plates with the closer spacing and lower dielectric constant. When the faster wave reaches the inner extents of the outer and inner conductive plates, it reflects back outward and reverses the field in that segment of the dielectric core. All the field segments in the dielectric core are then in unipolar agreement until the slower wave finally propagates to the third dielectric core across the dielectric plates with the wider spacing and higher dielectric constant. During such unipolar agreement, particles in the core are accelerated with gradients that exceed twenty megavolts per meter.

Major Oil Plays In Utah And Vicinity

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

Thomas Chidsey

2007-12-31

Utah oil fields have produced over 1.33 billion barrels (211 million m{sup 3}) of oil and hold 256 million barrels (40.7 million m{sup 3}) of proved reserves. The 13.7 million barrels (2.2 million m3) of production in 2002 was the lowest level in over 40 years and continued the steady decline that began in the mid-1980s. However, in late 2005 oil production increased, due, in part, to the discovery of Covenant field in the central Utah Navajo Sandstone thrust belt ('Hingeline') play, and to increased development drilling in the central Uinta Basin, reversing the decline that began in the mid-1980s.more » The Utah Geological Survey believes providing play portfolios for the major oil-producing provinces (Paradox Basin, Uinta Basin, and thrust belt) in Utah and adjacent areas in Colorado and Wyoming can continue this new upward production trend. Oil plays are geographic areas with petroleum potential caused by favorable combinations of source rock, migration paths, reservoir rock characteristics, and other factors. The play portfolios include descriptions and maps of the major oil plays by reservoir; production and reservoir data; case-study field evaluations; locations of major oil pipelines; identification and discussion of land-use constraints; descriptions of reservoir outcrop analogs; and summaries of the state-of-the-art drilling, completion, and secondary/tertiary recovery techniques for each play. The most prolific oil reservoir in the Utah/Wyoming thrust belt province is the eolian, Jurassic Nugget Sandstone, having produced over 288 million barrels (46 million m{sup 3}) of oil and 5.1 trillion cubic feet (145 billion m{sup 3}) of gas. Traps form on discrete subsidiary closures along major ramp anticlines where the depositionally heterogeneous Nugget is also extensively fractured. Hydrocarbons in Nugget reservoirs were generated from subthrust Cretaceous source rocks. The seals for the producing horizons are overlying argillaceous and gypsiferous beds in the Jurassic Twin Creek Limestone, or a low-permeability zone at the top of the Nugget. The Nugget Sandstone thrust belt play is divided into three subplays: (1) Absaroka thrust - Mesozoic-cored shallow structures, (2) Absaroka thrust - Mesozoic-cored deep structures, and (3) Absaroka thrust - Paleozoic-cored shallow structures. Both of the Mesozoic-cored structures subplays represent a linear, hanging wall, ramp anticline parallel to the leading edge of the Absaroka thrust. Fields in the shallow Mesozoic subplay produce crude oil and associated gas; fields in the deep subplay produce retrograde condensate. The Paleozoic-cored structures subplay is located immediately west of the Mesozoic-cored structures subplays. It represents a very continuous and linear, hanging wall, ramp anticline where the Nugget is truncated against a thrust splay. Fields in this subplay produce nonassociated gas and condensate. Traps in these subplays consist of long, narrow, doubly plunging anticlines. Prospective drilling targets are delineated using high-quality, two-dimensional and three-dimensional seismic data, forward modeling/visualization tools, and other state-of-the-art techniques. Future Nugget Sandstone exploration could focus on more structurally complex and subtle, thrust-related traps. Nugget structures may be present beneath the leading edge of the Hogsback thrust and North Flank fault of the Uinta uplift. The Jurassic Twin Creek Limestone play in the Utah/Wyoming thrust belt province has produced over 15 million barrels (2.4 million m{sup 3}) of oil and 93 billion cubic feet (2.6 billion m{sup 3}) of gas. Traps form on discrete subsidiary closures along major ramp anticlines where the low-porosity Twin Creek is extensively fractured. Hydrocarbons in Twin Creek reservoirs were generated from subthrust Cretaceous source rocks. The seals for the producing horizons are overlying argillaceous and clastic beds, and non-fractured units within the Twin Creek. The Twin Creek Limestone thrust belt play is divided into two subplays: (1) Absaroka thrust-Mesozoic-cored structures and (2) Absaroka thrust - Paleozoic-cored structures. The Mesozoic-cored structures subplay represents a linear, hanging wall, ramp anticline parallel to the leading edge of the Absaroka thrust. Fields in this subplay produce crude oil and associated gas. The Paleozoic-cored structures subplay is located immediately west of the Mesozoic-cored structures subplay. It represents a very continuous and linear, hanging wall, ramp anticline where the Twin Creek is truncated against a thrust splay. Fields in this subplay produce nonassociated gas and condensate. Traps in both subplays consist of long, narrow, doubly plunging anticlines.« less

Computer Simulation To Assess The Feasibility Of Coring Magma

NASA Astrophysics Data System (ADS)

Su, J.; Eichelberger, J. C.

2017-12-01

Lava lakes on Kilauea Volcano, Hawaii have been successfully cored many times, often with nearly complete recovery and at temperatures exceeding 1100oC. Water exiting nozzles on the diamond core bit face quenches melt to glass just ahead of the advancing bit. The bit readily cuts a clean annulus and the core, fully quenched lava, passes smoothly into the core barrel. The core remains intact after recovery, even when there are comparable amounts of glass and crystals with different coefficients of thermal expansion. The unique resulting data reveal the rate and sequence of crystal growth in cooling basaltic lava and the continuous liquid line of descent as a function of temperature from basalt to rhyolite. Now that magma bodies, rather than lava pooled at the surface, have been penetrated by geothermal drilling, the question arises as to whether similar coring could be conducted at depth, providing fundamentally new insights into behavior of magma. This situation is considerably more complex because the coring would be conducted at depths exceeding 2 km and drilling fluid pressures of 20 MPa or more. Criteria that must be satisfied include: 1) melt is quenched ahead of the bit and the core itself must be quenched before it enters the barrel; 2) circulating drilling fluid must keep the temperature of the coring assembling cooled to within operational limits; 3) the drilling fluid column must nowhere exceed the local boiling point. A fluid flow simulation was conducted to estimate the process parameters necessary to maintain workable temperatures during the coring operation. SolidWorks Flow Simulation was used to estimate the effect of process parameters on the temperature distribution of the magma immediately surrounding the borehole and of drilling fluid within the bottom-hole assembly (BHA). A solid model of the BHA was created in SolidWorks to capture the flow behavior around the BHA components. Process parameters used in the model include the fluid properties and temperature of magma, coolant flow rate, rotation speed, and rate of penetration (ROP). The modeling results indicate that there are combinations of process parameters that will provide sufficient cooling to enable the desired coring process in magma.

Wzi is an outer membrane lectin that underpins group 1 capsule assembly in Escherichia coli.

PubMed

Bushell, Simon R; Mainprize, Iain L; Wear, Martin A; Lou, Hubing; Whitfield, Chris; Naismith, James H

2013-05-07

Many pathogenic bacteria encase themselves in a polysaccharide capsule that provides a barrier to the physical and immunological challenges of the host. The mechanism by which the capsule assembles around the bacterial cell is unknown. Wzi, an integral outer-membrane protein from Escherichia coli, has been implicated in the formation of group 1 capsules. The 2.6 Å resolution structure of Wzi reveals an 18-stranded β-barrel fold with a novel arrangement of long extracellular loops that blocks the extracellular entrance and a helical bundle that plugs the periplasmic end. Mutagenesis shows that specific extracellular loops are required for in vivo capsule assembly. The data show that Wzi binds the K30 carbohydrate polymer and, crucially, that mutants functionally deficient in vivo show no binding to K30 polymer in vitro. We conclude that Wzi is a novel outer-membrane lectin that assists in the formation of the bacterial capsule via direct interaction with capsular polysaccharides. Copyright © 2013 Elsevier Ltd. All rights reserved.

The WD40 Protein BamB Mediates Coupling of BAM Complexes into Assembly Precincts in the Bacterial Outer Membrane.

PubMed

Gunasinghe, Sachith D; Shiota, Takuya; Stubenrauch, Christopher J; Schulze, Keith E; Webb, Chaille T; Fulcher, Alex J; Dunstan, Rhys A; Hay, Iain D; Naderer, Thomas; Whelan, Donna R; Bell, Toby D M; Elgass, Kirstin D; Strugnell, Richard A; Lithgow, Trevor

2018-05-29

The β-barrel assembly machinery (BAM) complex is essential for localization of surface proteins on bacterial cells, but the mechanism by which it functions is unclear. We developed a direct stochastic optical reconstruction microscopy (dSTORM) methodology to view the BAM complex in situ. Single-cell analysis showed that discrete membrane precincts housing several BAM complexes are distributed across the E. coli surface, with a nearest neighbor distance of ∼200 nm. The auxiliary lipoprotein subunit BamB was crucial for this spatial distribution, and in situ crosslinking shows that BamB makes intimate contacts with BamA and BamB in neighboring BAM complexes within the precinct. The BAM complex precincts swell when outer membrane protein synthesis is maximal, visual proof that the precincts are active in protein assembly. This nanoscale interrogation of the BAM complex in situ suggests a model whereby bacterial outer membranes contain highly organized assembly precincts to drive integral protein assembly. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

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.

The Effect of Lipopolysaccharide Core Oligosaccharide Size on the Electrostatic Binding of Antimicrobial Proteins to Models of the Gram Negative Bacterial Outer Membrane

PubMed Central

2016-01-01

Understanding the electrostatic interactions between bacterial membranes and exogenous proteins is crucial to designing effective antimicrobial agents against Gram-negative bacteria. Here we study, using neutron reflecometry under multiple isotopic contrast conditions, the role of the uncharged sugar groups in the outer core region of lipopolysaccharide (LPS) in protecting the phosphate-rich inner core region from electrostatic interactions with antimicrobial proteins. Models of the asymmetric Gram negative outer membrane on silicon were prepared with phopshatidylcholine (PC) in the inner leaflet (closest to the silicon), whereas rough LPS was used to form the outer leaflet (facing the bulk solution). We show how salt concentration can be used to reversibly alter the binding affinity of a protein antibiotic colicin N (ColN) to the anionic LPS confirming that the interaction is electrostatic in nature. By examining the interaction of ColN with two rough LPS types with different-sized core oligosaccharide regions we demonstrate the role of uncharged sugars in blocking short-range electrostatic interactions between the cationic antibiotics and the vulnerable anionic phosphate groups. PMID:27003358

Transient state kinetic investigation of ferritin iron release

NASA Astrophysics Data System (ADS)

Ciasca, G.; Papi, M.; Chiarpotto, M.; Rodio, M.; Campi, G.; Rossi, C.; De Sole, P.; Bianconi, A.

2012-02-01

Increased iron concentration in tissues appears to be a factor in the genesis and development of inflammatory and degenerative diseases. By means of real-time small angle x-ray scattering measurements, we studied the kinetics of iron release from the ferritin inorganic core as a function of time and distance from the iron core centre. Accordingly, the iron release process follows a three step model: (i) a defect nucleation in the outer part of the mineral core, (ii) the diffusion of the reducing agent towards the inner part of the core, and (iii) the erosion of the core from the inner to the outer part.

Current State of Theoretical and Experimental Studies of the Voltage-Dependent Anion Channel (VDAC)

PubMed Central

Noskov, Sergei Yu.; Rostovtseva, Tatiana K.; Chamberlin, Adam C.; Teijido, Oscar; Jiang, Wei; Bezrukov, Sergey M.

2016-01-01

Voltage-dependent anion channel (VDAC), the major channel of the mitochondrial outer membrane provides a controlled pathway for respiratory metabolites in and out of the mitochondria. In spite of the wealth of experimental data from structural, biochemical, and biophysical investigations, the exact mechanisms governing selective ion and metabolite transport, especially the role of titratable charged residues and interactions with soluble cytosolic proteins, remain hotly debated in the field. The computational advances hold a promise to provide a much sought-after solution to many of the scientific disputes around solute and ion transport through VDAC and hence, across the mitochondrial outer membrane. In this review, we examine how Molecular Dynamics, Free Energy, and Brownian Dynamics simulations of the large β-barrel channel, VDAC, advanced our understanding. We will provide a short overview of non-conventional techniques and also discuss examples of how the modeling excursions into VDAC biophysics prospectively aid experimental efforts. PMID:26940625

Detailed Characteristics of Radiation Belt Electrons Revealed by CSSWE/REPTile Measurements

NASA Astrophysics Data System (ADS)

Zhang, K.; Li, X.; Schiller, Q.; Gerhardt, D. T.; Millan, R. M.

2016-12-01

The outer radiation belt electrons are highly dynamic. We study the detailed characteristics of the relativistic electrons in the outer belt using measurements from the Colorado Student Space Weather Experiment (CSSWE) mission, a low Earth orbit Cubesat, which transverses the radiation belt four times in one orbit ( 1.5 hr) and has the advantage of measuring the dynamic activities of the electrons including their rapid precipitations. Among the features of the relativistic electrons, we show the measured electron distribution as a function of geomagnetic activities and local magnetic field strength. Moreover, a specific precipitation band, which happened on 19 Jan 2013, is investigated based on the conjunctive measurement of CSSWE and the Balloon Array for Radiation belt Relativistic Electron Losses (BARREL). In this precipitation band event, the net loss of the 0.58 1.63 MeV electrons (L=3.5 6) is estimated to account for 6.84% of the total electron content.

Core break-off mechanism

NASA Technical Reports Server (NTRS)

Myrick, Thomas M. (Inventor)

2003-01-01

A mechanism for breaking off and retaining a core sample of a drill drilled into a ground substrate has an outer drill tube and an inner core break-off tube sleeved inside the drill tube. The break-off tube breaks off and retains the core sample by a varying geometric relationship of inner and outer diameters with the drill tube. The inside diameter (ID) of the drill tube is offset by a given amount with respect to its outer diameter (OD). Similarly, the outside diameter (OD) of the break-off tube is offset by the same amount with respect to its inner diameter (ID). When the break-off tube and drill tube are in one rotational alignment, the two offsets cancel each other such that the drill can operate the two tubes together in alignment with the drill axis. When the tubes are rotated 180 degrees to another positional alignment, the two offsets add together causing the core sample in the break-off tube to be displaced from the drill axis and applying shear forces to break off the core sample.

Similarity in Shape Dictates Signature Intrinsic Dynamics Despite No Functional Conservation in TIM Barrel Enzymes

PubMed Central

Tiwari, Sandhya P.; Reuter, Nathalie

2016-01-01

The conservation of the intrinsic dynamics of proteins emerges as we attempt to understand the relationship between sequence, structure and functional conservation. We characterise the conservation of such dynamics in a case where the structure is conserved but function differs greatly. The triosephosphate isomerase barrel fold (TBF), renowned for its 8 β-strand-α-helix repeats that close to form a barrel, is one of the most diverse and abundant folds found in known protein structures. Proteins with this fold have diverse enzymatic functions spanning five of six Enzyme Commission classes, and we have picked five different superfamily candidates for our analysis using elastic network models. We find that the overall shape is a large determinant in the similarity of the intrinsic dynamics, regardless of function. In particular, the β-barrel core is highly rigid, while the α-helices that flank the β-strands have greater relative mobility, allowing for the many possibilities for placement of catalytic residues. We find that these elements correlate with each other via the loops that link them, as opposed to being directly correlated. We are also able to analyse the types of motions encoded by the normal mode vectors of the α-helices. We suggest that the global conservation of the intrinsic dynamics in the TBF contributes greatly to its success as an enzymatic scaffold both through evolution and enzyme design. PMID:27015412

Reverse Flow Engine Core Having a Ducted Fan with Integrated Secondary Flow Blades

NASA Technical Reports Server (NTRS)

Kisska, Michael K. (Inventor); Princen, Norman H. (Inventor); Kuehn, Mark S. (Inventor); Cosentino, Gary B. (Inventor)

2014-01-01

Secondary air flow is provided for a ducted fan having a reverse flow turbine engine core driving a fan blisk. The fan blisk incorporates a set of thrust fan blades extending from an outer hub and a set of integral secondary flow blades extending intermediate an inner hub and the outer hub. A nacelle provides an outer flow duct for the thrust fan blades and a secondary flow duct carries flow from the integral secondary flow blades as cooling air for components of the reverse flow turbine engine.

Seismic structures in the inner and outer core constrained by the PKP observations near the caustic distance range

NASA Astrophysics Data System (ADS)

Yu, W.; Wen, L.; Niu, F.

2002-05-01

We have extensively collected PKP waveforms around the PKP caustic distance range (141o - 147o) recorded in several dense regional arrays and the Global Seismic Network covering from 1990 to 2000. PKP observations at this distance range (141o - 147o) are usually purposely avoided in travel time analyses, because of the interference of various PKP branches. The observations there, however, will be extremely useful for constraining the seismic structures at both the top of the inner core and the bottom of the outer core. Moreover, because PKIKP phases sample a depth range of 100 km - 170 km below the inner-core boundary at this distant range, their observations fill the sampling depth gap between the PKiKP-PKIKP observations at the smaller distances and the PKPbc-PKIKP phases at the larger distances. Before the PKP caustics (141o - 145o), the diffracted PKP phases near the B caustics (PKPBdiff) and PKiKP phases are discernible in the long-period seismograms, and their differential travel times and waveforms could be used to constrain seismic structures at the bottom of the outer core and/or at the base of the mantle. The observed long-period PKiKP-PKPBdiff waveforms exhibit a hemispheric difference between those sampling the "eastern" and "western" hemispheres, with those sampling the "western" hemisphere showing larger time separations between the two phases. These observations can be explained by models with P velocity gradients of 0.0806 (km/s)/ 200 km for the "western" hemisphere and 0.114 (km/s)/200 km for the "eastern" hemisphere at the bottom of the outer core. Alternatively, these observations can also be explained by models with different velocity structures at the bottom 200 km of the mantle with P velocity variations in an order of 3 percent with respect to PREM. Broadband PKP observations after the PKP caustics (145o - 147o), on the other hand, provide high-quality constraints on the seismic structures at both the top of the inner core and the bottom of the outer core, as PKPbc phases can be used as excellent reference phases. We explore seismic models in both the bottom of the outer core and the top of the inner core, which can consistently explain the seismic observations at the caustic distance range (141o - 147o) and the PKiKP-PKIKP observations at the closer distances (Niu and Wen, Nature, 410, 1081-1084, 2001, Wen and Niu, JGR, submitted).

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.

Experimental and Theoretical Investigations on Viscosity of Fe-Ni-C Liquids at High Pressures

NASA Astrophysics Data System (ADS)

Chen, B.; Lai, X.; Wang, J.; Zhu, F.; Liu, J.; Kono, Y.

2016-12-01

Understanding and modeling of Earth's core processes such as geodynamo and heat flow via convection in liquid outer cores hinges on the viscosity of candidate liquid iron alloys under core conditions. Viscosity estimates from various methods of the metallic liquid of the outer core, however, span up to 12 orders of magnitude. Due to experimental challenges, viscosity measurements of iron liquids alloyed with lighter elements are scarce and conducted at conditions far below those expected for the outer core. In this study, we adopt a synergistic approach by integrating experiments at experimentally-achievable conditions with computations up to core conditions. We performed viscosity measurements based on the modified Stokes' floating sphere viscometry method for the Fe-Ni-C liquids at high pressures in a Paris-Edinburgh press at Sector 16 of the Advanced Photon Source, Argonne National Laboratory. Our results show that the addition of 3-5 wt.% carbon to iron-nickel liquids has negligible effect on its viscosity at pressures lower than 5 GPa. The viscosity of the Fe-Ni-C liquids, however, becomes notably higher and increases by a factor of 3 at 5-8 GPa. Similarly, our first-principles molecular dynamics calculations up to Earth's core pressures show a viscosity change in Fe-Ni-C liquids at 5 GPa. The significant change in the viscosity is likely due to a liquid structural transition of the Fe-Ni-C liquids as revealed by our X-ray diffraction measurements and first-principles molecular dynamics calculations. The observed correlation between structure and physical properties of liquids permit stringent benchmark test of the computational liquid models and contribute to a more comprehensive understanding of liquid properties under high pressures. The interplay between experiments and first-principles based modeling is shown to be a practical and effective methodology for studying liquid properties under outer core conditions that are difficult to reach with the current static high-pressure capabilities. The new viscosity data from experiments and computations would provide new insights into the internal dynamics of the outer core.

Experimental Design for Evaluation of Co-extruded Refractory Metal/Nickel Base Superalloy Joints

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

ME Petrichek

2005-12-16

Prior to the restructuring of the Prometheus Program, the NRPCT was tasked with delivering a nuclear space reactor. Potential NRPCT nuclear space reactor designs for the Prometheus Project required dissimilar materials to be in contact with each other while operating at extreme temperatures under irradiation. As a result of the high reactor core temperatures, refractory metals were the primary candidates for many of the reactor structural and cladding components. They included the tantalum-base alloys ASTAR-811C and Ta-10W, the niobium-base alloy FS-85, and the molybdenum base alloys Moly 41-47.5 Rhenium. The refractory metals were to be joined to candidate nickel basemore » alloys such as Haynes 230, Alloy 617, or Nimonic PE 16 either within the core if the nickel-base alloys were ultimately selected to form the outer core barrel, or at a location exterior to the core if the nickel-base alloys were limited to components exterior to the core. To support the need for dissimilar metal joints in the Prometheus Project, a co-extrusion experiment was proposed. There are several potential methods for the formation of dissimilar metal joints, including explosive bonding, friction stir welding, plasma spray, inertia welding, HIP, and co-extrusion. Most of these joining methods are not viable options because they result in the immediate formation of brittle intermetallics. Upon cooling, intermetallics form in the weld fusion zone between the joined metals. Because brittle intermetallics do not form during the initial bonding process associated with HIP, co-extrusion, and explosive bonding, these three joining procedures are preferred for forming dissimilar metal joints. In reference to a Westinghouse Astronuclear Laboratory report done under a NASA sponsored program, joints that were fabricated between similar materials via explosive bonding had strengths that were directly affected by the width of the diffusion barrier. It was determined that the diffusion zone should not exceed a critical thickness (0.0005 in.). A diffusion barrier that exceeded this thickness would likely fail. The joint fabrication method must therefore mechanically bond the two materials causing little or no interdiffusion upon formation. Co-extrusion fits this description since it forms a mechanical joint between two materials by using heat and pressure. The two materials to be extruded are first assembled and sealed within a co-extrusion billet which is subsequently heated and then extruded through a die. For a production application, once the joint is formed, it is dejacketed to remove the outer canister. The remaining piece consists of two materials bonded together with a thin diffusion barrier. Therefore, the long-term stability of the joint is determined primarily by the kinetics of interdiffusion reaction between the two materials. An experimental design for co-extrusion of refractory metals and nickel-based superalloys was developed to evaluate this joining process and determine the long-term stability of the joints.« less

Electromagnetic pump stator core

DOEpatents

Fanning, A.W.; Olich, E.E.; Dahl, L.R.

1995-01-17

A stator core for supporting an electrical coil includes a plurality of groups of circumferentially abutting flat laminations which collectively form a bore and perimeter. A plurality of wedges are interposed between the groups, with each wedge having an inner edge and a thicker outer edge. The wedge outer edges abut adjacent ones of the groups to provide a continuous path around the perimeter. 21 figures.

Electromagnetic pump stator core

DOEpatents

Fanning, Alan W.; Olich, Eugene E.; Dahl, Leslie R.

1995-01-01

A stator core for supporting an electrical coil includes a plurality of groups of circumferentially abutting flat laminations which collectively form a bore and perimeter. A plurality of wedges are interposed between the groups, with each wedge having an inner edge and a thicker outer edge. The wedge outer edges abut adjacent ones of the groups to provide a continuous path around the perimeter.

Magnetohydrodynamic Convection in the Outer Core and its Geodynamic Consequences

NASA Technical Reports Server (NTRS)

Kuang, Weijia; Chao, Benjamin F.; Fang, Ming

2004-01-01

The Earth's fluid outer core is in vigorous convection through much of the Earth's history. In addition to generating and maintaining Earth s time-varying magnetic field (geodynamo), the core convection also generates mass redistribution in the core and a dynamical pressure field on the core-mantle boundary (CMB). All these shall result in various core-mantle interactions, and contribute to surface geodynamic observables. For example, electromagnetic core-mantle coupling arises from finite electrically conducting lower mantle; gravitational interaction occurs between the cores and the heterogeneous mantle; mechanical coupling may also occur when the CMB topography is aspherical. Besides changing the mantle rotation via the coupling torques, the mass-redistribution in the core shall produce a spatial-temporal gravity anomaly. Numerical modeling of the core dynamical processes contributes in several geophysical disciplines. It helps explain the physical causes of surface geodynamic observables via space geodetic techniques and other means, e.g. Earth's rotation variation on decadal time scales, and secular time-variable gravity. Conversely, identification of the sources of the observables can provide additional insights on the dynamics of the fluid core, leading to better constraints on the physics in the numerical modeling. In the past few years, our core dynamics modeling efforts, with respect to our MoSST model, have made significant progress in understanding individual geophysical consequences. However, integrated studies are desirable, not only because of more mature numerical core dynamics models, but also because of inter-correlation among the geophysical phenomena, e.g. mass redistribution in the outer core produces not only time-variable gravity, but also gravitational core-mantle coupling and thus the Earth's rotation variation. They are expected to further facilitate multidisciplinary studies of core dynamics and interactions of the core with other components of the Earth.

Core-Cutoff Tool

NASA Technical Reports Server (NTRS)

Gheen, Darrell

2007-01-01

A tool makes a cut perpendicular to the cylindrical axis of a core hole at a predetermined depth to free the core at that depth. The tool does not damage the surrounding material from which the core was cut, and it operates within the core-hole kerf. Coring usually begins with use of a hole saw or a hollow cylindrical abrasive cutting tool to make an annular hole that leaves the core (sometimes called the plug ) in place. In this approach to coring as practiced heretofore, the core is removed forcibly in a manner chosen to shear the core, preferably at or near the greatest depth of the core hole. Unfortunately, such forcible removal often damages both the core and the surrounding material (see Figure 1). In an alternative prior approach, especially applicable to toxic or fragile material, a core is formed and freed by means of milling operations that generate much material waste. In contrast, the present tool eliminates the damage associated with the hole-saw approach and reduces the extent of milling operations (and, hence, reduces the waste) associated with the milling approach. The present tool (see Figure 2) includes an inner sleeve and an outer sleeve and resembles the hollow cylindrical tool used to cut the core hole. The sleeves are thin enough that this tool fits within the kerf of the core hole. The inner sleeve is attached to a shaft that, in turn, can be attached to a drill motor or handle for turning the tool. This tool also includes a cutting wire attached to the distal ends of both sleeves. The cutting wire is long enough that with sufficient relative rotation of the inner and outer sleeves, the wire can cut all the way to the center of the core. The tool is inserted in the kerf until its distal end is seated at the full depth. The inner sleeve is then turned. During turning, frictional drag on the outer core pulls the cutting wire into contact with the core. The cutting force of the wire against the core increases with the tension in the wire and, hence, with the frictional drag acting on the outer sleeve. As the wire cuts toward the center of the core, the inner sleeve rotates farther with respect to the outer sleeve. Once the wire has cut to the center of the core, the tool and the core can be removed from the hole. The proper choice of cutting wire depends on the properties of the core material. For a sufficiently soft core material, a nonmetallic monofilament can be used. For a rubber-like core material, a metal wire can be used. For a harder core material, it is necessary to use an abrasive wire, and the efficiency of the tool can be increased greatly by vacuuming away the particles generated during cutting. For a core material that can readily be melted or otherwise cut by use of heat, it could be preferable to use an electrically heated cutting wire. In such a case, electric current can be supplied to the cutting wire, from an electrically isolated source, via rotating contact rings mounted on the sleeves.

Twenty barrel in situ pipe gun type solid hydrogen pellet injector for the Large Helical Device.

PubMed

Sakamoto, Ryuichi; Motojima, Gen; Hayashi, Hiromi; Inoue, Tomoyuki; Ito, Yasuhiko; Ogawa, Hideki; Takami, Shigeyuki; Yokota, Mitsuhiro; Yamada, Hiroshi

2013-08-01

A 20 barrel solid hydrogen pellet injector, which is able to inject 20 cylindrical pellets with a diameter and length of between 3.0 and 3.8 mm at the velocity of 1200 m/s, has been developed for the purpose of direct core fueling in LHD (Large Helical Device). The in situ pipe gun concept with the use of compact cryo-coolers enables stable operation as a fundamental facility in plasma experiments. The combination of the two types of pellet injection timing control modes, i.e., pre-programing mode and real-time control mode, allows the build-up and sustainment of high density plasma around the density limit. The pellet injector has demonstrated stable operation characteristics during the past three years of LHD experiments.

A method for quantitative mapping of thick oil spills using imaging spectroscopy

USGS Publications Warehouse

Clark, Roger N.; Swayze, Gregg A.; Leifer, Ira; Livo, K. Eric; Kokaly, Raymond F.; Hoefen, Todd; Lundeen, Sarah; Eastwood, Michael; Green, Robert O.; Pearson, Neil; Sarture, Charles; McCubbin, Ian; Roberts, Dar; Bradley, Eliza; Steele, Denis; Ryan, Thomas; Dominguez, Roseanne; ,

2010-01-01

In response to the Deepwater Horizon oil spill in the Gulf of Mexico, a method of near-infrared imaging spectroscopic analysis was developed to map the locations of thick oil floating on water. Specifically, this method can be used to derive, in each image pixel, the oil-to-water ratio in oil emulsions, the sub-pixel areal fraction, and its thicknesses and volume within the limits of light penetration into the oil (up to a few millimeters). The method uses the shape of near-infrared (NIR) absorption features and the variations in the spectral continuum due to organic compounds found in oil to identify different oil chemistries, including its weathering state and thickness. The method is insensitive to complicating conditions such as moderate aerosol scattering and reflectance level changes from other conditions, including moderate sun glint. Data for this analysis were collected by the NASA Airborne Visual Infrared Imaging Spectrometer (AVIRIS) instrument, which was flown over the oil spill on May 17, 2010. Because of the large extent of the spill, AVIRIS flight lines could cover only a portion of the spill on this relatively calm, nearly cloud-free day. Derived lower limits for oil volumes within the top few millimeters of the ocean surface directly probed with the near-infrared light detected in the AVIRIS scenes were 19,000 (conservative assumptions) to 34,000 (aggressive assumptions) barrels of oil. AVIRIS covered about 30 percent of the core spill area, which consisted of emulsion plumes and oil sheens. Areas of oil sheen but lacking oil emulsion plumes outside of the core spill were not evaluated for oil volume in this study. If the core spill areas not covered by flight lines contained similar amounts of oil and oil-water emulsions, then extrapolation to the entire core spill area defined by a MODIS (Terra) image collected on the same day indicates a minimum of 66,000 to 120,000 barrels of oil was floating on the surface. These estimates are preliminary and subject to revision pending further analysis. Based on laboratory measurements, near-infrared (NIR) photons penetrate only a few millimeters into oil-water emulsions. As such, the oil volumes derived with this method are lower limits. Further, the detection is only of thick surface oil and does not include sheens, underwater oil, or oil that had already washed onto beaches and wetlands, oil that had been burned or evaporated as of May 17. Because NIR light penetration within emulsions is limited, and having made field observations that oil emulsions sometimes exceeded 20 millimeters in thickness, we estimate that the volume of oil, including oil thicker than can be probed in the AVIRIS imagery, is possibly as high as 150,000 barrels in the AVIRIS scenes. When this value is projected to the entire spill, it gives a volume of about 500,000 barrels for thick oil remaining on the sea surface as of May 17. AVIRIS data cannot be used to confirm this higher volume, and additional field work including more in-situ measurements of oil thickness would be required to confirm this higher oil volume. Both the directly detected minimum range of oil volume, and the higher possible volume projection for oil thicker than can be probed with NIR spectroscopy imply a significantly higher total volume of oil relative to that implied by the early NOAA (National Oceanic and Atmospheric Administration) estimate of 5,000 barrels per day reported on their Web site.

Mechanical thermal motor

NASA Technical Reports Server (NTRS)

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

1976-01-01

An apparatus is described for converting thermal energy such as solar energy into mechanical motion for driving fluid pumps and similar equipment. The thermal motor comprises an inner concentric cylinder carried by a stationary core member. The core member has a cylindrical disc plate fixed adjacent to a lower portion and extending radially from it. An outer concentric cylinder rotatably carried on the disc plate defining a space between the inner and outer concentric cylinders. A spiral tubular member encircles the inner concentric cylinder and is contained within the space between the inner and outer cylinders. One portion is connected to the inner concentric cylinder and a second portion connected to the outer concentric cylinder. A heated fluid is conveyed through the tubular member and is periodically cooled causing the tubular member to expand and contract. This causes the outer concentric cylinder to reciprocally rotate on the base plate accordingly. The reciprocating motion of the outer concentric cylinder is then utilized to drive a pump member in a pump chamber.

Composition of the low seismic velocity E' layer at the top of Earth's core

NASA Astrophysics Data System (ADS)

Badro, J.; Brodholt, J. P.

2017-12-01

Evidence for a layer (E') at the top of the outer core has been available since the '90s and while different studies suggest slightly different velocity contrasts and thicknesses, the common observation is that the layer has lower velocities than the bulk outer core (PREM). Although there are no direct measurements on the density of this layer, dynamic stability requires it to be less dense than the bulk outer core under those same pressure and temperature conditions. Using ab initio simulations on Fe-Ni-S-C-O-Si liquids we constrain the origin and composition of the low-velocity layer E' at the top of Earth's outer core. We find that increasing the concentration of any light-element always increases velocity and so a low-velocity and low-density layer (for stability) cannot be made by simply increasing light element concentration. This rules out barodiffusion or upwards sedimentation of a light phase for its origin. However, exchanging elements can—depending on the elements exchanged—produce such a layer. We evaluate three possibilities. Firstly, crystallization of a light phase from a core containing more than one light element may make such a layer, but only if the crystalizing phase is very Fe-rich, which is at odds with available phase diagrams at CMB conditions. Secondly, the E' layer may result from incomplete mixing of an early Earth core with a late impactor, depending on the light element compositions of the impactor and Earth's core, but such a primordial stratification is neither supported by dynamical models of the core nor thermodynamic models of core merger after the giant impact. The last and most plausible scenario is core-mantle chemical interaction; using thermodynamic models for metal-silicate partitioning of silicon and oxygen at CMB conditions, we show that a reaction between the core and an FeO-rich basal magma ocean can enrich the core in oxygen while depleting it in silicon, in relative amounts that produce a light and slow layer consistent with seismological observations.

Compact Hybrid Laser Rod and Laser System

NASA Technical Reports Server (NTRS)

Pierrottet, Diego F. (Inventor); Busch, George E. (Inventor); Amzajerdian, Farzin (Inventor)

2017-01-01

A hybrid fiber rod includes a fiber core and inner and outer cladding layers. The core is doped with an active element. The inner cladding layer surrounds the core, and has a refractive index substantially equal to that of the core. The outer cladding layer surrounds the inner cladding layer, and has a refractive index less than that of the core and inner cladding layer. The core length is about 30 to 2000 times the core diameter. A hybrid fiber rod laser system includes an oscillator laser, modulating device, the rod, and pump laser diode(s) energizing the rod from opposite ends. The rod acts as a waveguide for pump radiation but allows for free-space propagation of laser radiation. The rod may be used in a laser resonator. The core length is less than about twice the Rayleigh range. Degradation from single-mode to multi-mode beam propagation is thus avoided.

Study on a New Combination Method and High Efficiency Outer Rotor Type Permanent Magnet Motors

NASA Astrophysics Data System (ADS)

Enomoto, Yuji; Kitamura, Masashi; Motegi, Yasuaki; Andoh, Takashi; Ochiai, Makoto; Abukawa, Toshimi

The segment stator core, high space factor coil, and high efficiency magnet are indispensable technologies in the development of compact and a high efficiency motors. But adoption of the segment stator core and high space factor coil has not progressed in the field of outer rotor type motors, for the reason that the inner components cannot be laser welded together. Therefore, we have examined a segment stator core combination technology for the purposes of getting a large increase in efficiency and realizing miniaturization. We have also developed a characteristic estimation method which provides the most suitable performance for segment stator core motors.

The Neurobiology and Psychiatric Perspective of Vaginismus: Linking the Pharmacological and Psycho-Social Interventions.

PubMed

Kadir, Zuri Shahidii; Sidi, Hatta; Kumar, Jaya; Das, Srijit; Midin, Marhani; Baharuddin, Najwa

2018-01-01

Vaginismus is an involuntary muscle contraction of the outer third of vaginal barrel causing sexual penetration almost impossible. It is generally classified under sexual pain disorder (SPD). In Diagnostic and Statistical Manual, 5th edition (DSM-5), it is classified under the new rubric of Genito-Pelvic Pain/Sexual Penetration Disorder. This fear-avoidance condition poses an ongoing significant challenge to the medical and health professionals due to the very demanding needs in health care despite its unpredictable prognosis. The etiology of vaginismus is complex: through multiple biopsycho- social processes, involving bidirectional connections between pelvic-genital (local) and higher mental function (central regulation). It has robust neural and psychological-cognitive loop feedback involvement. The internal neural circuit involves an inter-play of at least two-pathway systems, i.e. both "quick threat assessment" of occipital-limbic-occipital-prefrontal-pelvic-genital; and the chronic pain pathways through the genito-spinothalamic-parietal-pre-frontal system, respectively. In this review, a neurobiology root of vaginismus is deliberated with the central role of an emotional-regulating amygdala, and other neural loop, i.e. hippocampus and neo-cortex in the core psychopathology of fear, disgust, and sexual avoidance. Many therapists view vaginismus as a neglected art-and-science which demands a better and deeper understanding on the clinico-pathological correlation to enhance an effective model for the bio-psycho-social treatment. As vaginismus has a strong presentation in psychopathology, i.e. fear of penetration, phobic avoidance, disgust, and anticipatory anxiety, we highlighted a practical psychiatric approach to the clinical management of vaginismus, based on the current core knowledge in the perspective of neuroscience. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Iron-magnesium alloy in the Earth's Core

NASA Astrophysics Data System (ADS)

Dubrovinskaia, N.; Dubrovinsky, L.; Abrikosov, I.

2005-12-01

Composition of the Earth's outer core is a geochemical parameter crucial for understanding the evolution and current dynamics of our planet. Since it was recognized that the liquid metallic outer core is about 10% less dense than pure iron, different elements lighter than iron, including Si, S, O, C, and H, were proposed as major or at least significantly abundant in Earth's core. However, combination of experimental results with theoretical and geochemical considerations shows that it is unlikely that any one of these elements can account for the density deficit on its own. In series of experiments in a multianvil apparatus and in electrically- and laser-heated diamond anvil cells, we demonstrate that high pressure promotes solubility of magnesium in iron and at megabar pressure range more than 10 at% of Mg can dissolve in Fe. At pressures above 95 to 100 GPa, molten iron reacts with periclase MgO forming an iron-magnesium alloy and iron oxide. Our observations suggest that magnesium can be an important light element in Earth's outer core, but it cannot account for the seismologically determined density deficit on its own.

Outer continental shelf oil and gas activities in the Pacific (Southern California) and their onshore impacts: a summary report, May 1980

USGS Publications Warehouse

Macpherson, George S.; Bernstein, Janis

1980-01-01

Outer Continental Shelf (OCS) oil and gas exploration and development have been under way in the Pacific (Southern California) Region since 1966. During that time, there have been four Federal lease sales: in 1966, 1968, 1975 (Sale 35), and 1979 (Sale 48). Oil and gas production from three leases has been going on since 1968. It peaked in 1971 and now averages around 31,400 barrels of oil and 15.4 million cubic feet of gas per day. Discoveries on areas leased in the 1968 and 1975 sales have led to plans for eight new platforms to begin production in the early 1980's. Five platforms are in the eastern end of Santa Barbara Channel, one is in the western Channel, and two are in San Pedro Bay, south of Long Beach. Three rigs are doing exploratory drilling in the Region. The most recent estimates by the U.S. Geological Survey of remaining reserves for all identified fields in the Southern California Region are 695 million barrels of oil and 1,575 billion cubic feet of gas (January 1979). The USGS has also made risked estimates of economically recoverable oil and gas resources for all the leased tracts in the Region (March 1980). These risked estimates of economically recoverable resources are 394 billion barrels of oil and 1,295 billion cubic feet of gas. The USGS estimates of undiscovered recoverable resources for the entire Southern California OCS Region (January 1980) are 3,200 million barrels of oil and 3,400 billion cubic feet of gas. Because of the long history of oil and gas production in Southern California from wells onshore and in State waters, there are many existing facilities for the transportation, processing, and refining of oil and gas. Some of the expected new OCS production can be accommodated in these facilities. Four new onshore projects will be required. Two of these are under construction: (1) a 9.6-km (6-mi) onshore oil pipeline (capacity: 60,000 bpd) between Carpinteria (Santa Barbara County) and the existing Mobil-Rincon separation and treatment facility (Ventura County), and (2) a small supply base and dock (upgrade of existing facility) and a 0.4-hectare (1-acre) crude oil distribution facility in Long Beach (Los Angeles County), connected to landfall by a 3-km (1.8-mi) onshore pipeline. The two other facilities are awaiting permit approval: (1) a gas treatment plant at Las Flores Canyon (Santa Barbara County) and (2) a separation and treatment plant at Mandalay Beach (Ventura County) with 4 km (2.5 mi) of onshore pipeline on the same right-of-way from landfall to the plant and from the plant to an existing gas transmission line.

A Homology Model Reveals Novel Structural Features and an Immunodominant Surface Loop/Opsonic Target in the Treponema pallidum BamA Ortholog TP_0326

PubMed Central

Luthra, Amit; Anand, Arvind; Hawley, Kelly L.; LeDoyt, Morgan; La Vake, Carson J.; Caimano, Melissa J.; Cruz, Adriana R.; Salazar, Juan C.

2015-01-01

ABSTRACT We recently demonstrated that TP_0326 is a bona fide rare outer membrane protein (OMP) in Treponema pallidum and that it possesses characteristic BamA bipartite topology. Herein, we used immunofluorescence analysis (IFA) to show that only the β-barrel domain of TP_0326 contains surface-exposed epitopes in intact T. pallidum. Using the solved structure of Neisseria gonorrhoeae BamA, we generated a homology model of full-length TP_0326. Although the model predicts a typical BamA fold, the β-barrel harbors features not described in other BamAs. Structural modeling predicted that a dome comprised of three large extracellular loops, loop 4 (L4), L6, and L7, covers the barrel's extracellular opening. L4, the dome's major surface-accessible loop, contains mainly charged residues, while L7 is largely neutral and contains a polyserine tract in a two-tiered conformation. L6 projects into the β-barrel but lacks the VRGF/Y motif that anchors L6 within other BamAs. IFA and opsonophagocytosis assay revealed that L4 is surface exposed and an opsonic target. Consistent with B cell epitope predictions, immunoblotting and enzyme-linked immunosorbent assay (ELISA) confirmed that L4 is an immunodominant loop in T. pallidum-infected rabbits and humans with secondary syphilis. Antibody capture experiments using Escherichia coli expressing OM-localized TP_0326 as a T. pallidum surrogate further established the surface accessibility of L4. Lastly, we found that a naturally occurring substitution (Leu593 → Gln593) in the L4 sequences of T. pallidum strains affects antibody binding in sera from syphilitic patients. Ours is the first study to employ a “structure-to-pathogenesis” approach to map the surface topology of a T. pallidum OMP within the context of syphilitic infection. IMPORTANCE Previously, we reported that TP_0326 is a bona fide rare outer membrane protein (OMP) in Treponema pallidum and that it possesses the bipartite topology characteristic of a BamA ortholog. Using a homology model as a guide, we found that TP_0326 displays unique features which presumably relate to its function(s) in the biogenesis of T. pallidum's unorthodox OM. The model also enabled us to identify an immunodominant epitope in a large extracellular loop that is both an opsonic target and subject to immune pressure in a human population. Ours is the first study to follow a structure-to-pathogenesis approach to map the surface topology of a T. pallidum rare OMP within the context of syphilitic infection. PMID:25825429

Teleseismic Array Studies of Earth's Core-Mantle Boundary

NASA Astrophysics Data System (ADS)

Alexandrakis, Catherine

2011-12-01

The core mantle boundary (CMB) is an inaccessible and complex region, knowledge of which is vital to our understanding of many Earth processes. Above it is the heterogeneous lower-mantle. Below the boundary is the outer-core, composed of liquid iron, and/or nickel and some lighter elements. Elucidation of how these two distinct layers interact may enable researchers to better understand the geodynamo, global tectonics, and overall Earth history. One parameter that can be used to study structure and limit potential chemical compositions is seismic-wave velocity. Current global-velocity models have significant uncertainties in the 200 km above and below the CMB. In this thesis, these regions are studied using three methods. The upper outer core is studied using two seismic array methods. First, a modified vespa, or slant-stack method is applied to seismic observations at broadband seismic arrays, and at large, dense groups of broadband seismic stations dubbed 'virtual' arrays. Observations of core-refracted teleseismic waves, such as SmKS, are used to extract relative arrivaltimes. As with previous studies, lower -mantle heterogeneities influence the extracted arrivaltimes, giving significant scatter. To remove raypath effects, a new method was developed, called Empirical Transfer Functions (ETFs). When applied to SmKS waves, this method effectively isolates arrivaltime perturbations caused by outer core velocities. By removing raypath effects, the signals can be stacked further reducing scatter. The results of this work were published as a new 1D outer-core model, called AE09. This model describes a well-mixed outer core. Two array methods are used to detect lower mantle heterogeneities, in particular Ultra-Low Velocity Zones (ULVZs). The ETF method and beam forming are used to isolate a weak P-wave that diffracts along the CMB. While neither the ETF method nor beam forming could adequately image the low-amplitude phase, beam forms of two events indicate precursors to the SKS and SKKS phase, which may be ULVZ indicators. Finally, cross-correlated observed and modelled beams indicate a tendency towards a ULVZ-like lower mantle in the study region.

Topography at the inner core boundary

NASA Astrophysics Data System (ADS)

Lasbleis, M.; Forquenot, Q.; Deguen, R.

2017-12-01

Topography at the inner core boundary has been proposed to explain surprising seismic observations of some regional studies. Such observations are still debatted, and numerical values of possible inner core topography have been proposed ranging from no topography to "inner core mountains" (10km heigth over lengthscales of 20km, as in Dai et al. 2012). The inner core boundary is a peculiar boundary, as it is the place where the iron alloy constituting the core freezes. The existence of a significant topography on such a boundary is possible, but unlikely. At thermodynamic equilibrium, no topography is expected, as any material above the equilibrium radius would have melted and any below would have freezed. However, mechanical forcing may push the system out of equilibrium. Dynamical topography could be forced by convective flows in the inner core or by outer core heterogeneities. A topography induced by outer core convection would be short-lived when compared to geodynamical processes in the bulk of the inner core (τ ≈ 10-100 Myears), but long-lived compared to observations. Here, we would like to give a geodynamical perspective over inner core topography. We constrain plausible amplitude of inner core topography, and discuss the implications for seismic observations. We consider topography created by viscous flows in the bulk of the inner core and by variations of growth rate on regional lengthscale due to outer core convection. This approach allows us to consider both internal and external forcings on the topography. We treat topography forcings as stochastic processes, and calculate the probability of observing a given topography. Based on preliminary results, the high values for observed topography can not be interpreted as a normal behavior of core dynamics. If confirmed, the regions are likely to be anomalous and originated from outliers in the distribution of stochastic processes.

Core Formation Process and Light Elements in the Planetary Core

NASA Astrophysics Data System (ADS)

Ohtani, E.; Sakairi, T.; Watanabe, K.; Kamada, S.; Sakamaki, T.; Hirao, N.

2015-12-01

Si, O, and S are major candidates for light elements in the planetary core. In the early stage of the planetary formation, the core formation started by percolation of the metallic liquid though silicate matrix because Fe-S-O and Fe-S-Si eutectic temperatures are significantly lower than the solidus of the silicates. Therefore, in the early stage of accretion of the planets, the eutectic liquid with S enrichment was formed and separated into the core by percolation. The major light element in the core at this stage will be sulfur. The internal pressure and temperature increased with the growth of the planets, and the metal component depleted in S was molten. The metallic melt contained both Si and O at high pressure in the deep magma ocean in the later stage. Thus, the core contains S, Si, and O in this stage of core formation. Partitioning experiments between solid and liquid metals indicate that S is partitioned into the liquid metal, whereas O is weakly into the liquid. Partitioning of Si changes with the metallic iron phases, i.e., fcc iron-alloy coexisting with the metallic liquid below 30 GPa is depleted in Si. Whereas hcp-Fe alloy above 30 GPa coexisting with the liquid favors Si. This contrast of Si partitioning provides remarkable difference in compositions of the solid inner core and liquid outer core among different terrestrial planets. Our melting experiments of the Fe-S-Si and Fe-O-S systems at high pressure indicate the core-adiabats in small planets, Mercury and Mars, are greater than the slope of the solidus and liquidus curves of these systems. Thus, in these planets, the core crystallized at the top of the liquid core and 'snowing core' formation occurred during crystallization. The solid inner core is depleted in both Si and S whereas the liquid outer core is relatively enriched in Si and S in these planets. On the other hand, the core adiabats in large planets, Earth and Venus, are smaller than the solidus and liquidus curves of the systems. The inner core of these planets crystallized at the center of the core and it has the relatively Si rich inner core and the S enriched outer core. Based on melting and solid-liquid partitioning, the equation of state, and sound velocity of iron-light element alloys, we examined the plausible distribution of light elements in the liquid outer and solid inner cores of the terrestrial planets.

On the consequences of strong stable stratification at the top of earth's outer core

NASA Technical Reports Server (NTRS)

Bloxham, Jeremy

1990-01-01

The consequences of strong stable stratification at the top of the earth's fluid outer core are considered, concentrating on the generation of the geomagnetic secular variation. It is assumed that the core near the core-mantle boundary is both strongly stably stratified and free of Lorentz forces: it is found that this set of assumptions severely limits the class of possible motions, none of which is compatible with the geomagnetic secular variation. Relaxing either assumption is adequate: tangentially geostrophic flows are consistent with the secular variation if the assumption that the core is strongly stably stratified is relaxed (while retaining the assumption that Lorentz forces are negligible); purely toroidal flows may explain the secular variation if Lorentz forces are included.

The Major Outer Membrane Protein MopB Is Required for Twitching Movement and Affects Biofilm Formation and Virulence in Two Xylella fastidiosa strains.

PubMed

Chen, Hongyu; Kandel, Prem P; Cruz, Luisa F; Cobine, Paul A; De La Fuente, Leonardo

2017-11-01

MopB is a major outer membrane protein (OMP) in Xylella fastidiosa, a bacterial plant pathogen that causes losses on many economically important crops. Based on in silico analysis, the uncharacterized MopB protein of X. fastidiosa contains a β-barrel structure with an OmpA-like domain and a predicted calcium-binding motif. Here, MopB function was studied by mutational analysis taking advantage of the natural competence of X. fastidiosa. Mutants of mopB were constructed in two different X. fastidiosa strains, the type strain Temecula and the more virulent WM1-1. Deletion of the mopB gene impaired cell-to-cell aggregation, surface attachment, and biofilm formation in both strains. Interestingly, mopB deletion completely abolished twitching motility. Electron microscopy of the bacterial cell surface revealed that mopB deletion eliminated type IV and type I pili formation, potentially caused by destabilization of the outer membrane. Both mopB mutants showed reduced virulence using tobacco (Nicotiana tabacum) as a host under greenhouse conditions. These results suggest that MopB has pleiotropic functions in biofilm formation and twitching motility and is important for virulence of X. fastidiosa.

Δ98Δ, a minimalist model of antiparallel β-sheet proteins based on intestinal fatty acid binding protein

PubMed Central

Curto, Lucrecia María; Caramelo, Julio Javier; Franchini, Gisela Raquel; Delfino, José María

2009-01-01

The design of β-barrels has always been a formidable challenge for de novo protein design. For instance, a persistent problem is posed by the intrinsic tendency to associate given by free edges. From the opposite standpoint provided by the redesign of natural motifs, we believe that the intestinal fatty acid binding protein (IFABP) framework allows room for intervention, giving rise to abridged forms from which lessons on β-barrel architecture and stability could be learned. In this context, Δ98Δ (encompassing residues 29–126 of IFABP) emerges as a monomeric variant that folds properly, retaining functional activity, despite lacking extensive stretches involved in the closure of the β-barrel. Spectroscopic probes (fluorescence and circular dichroism) support the existence of a form preserving the essential determinants of the parent structure, albeit endowed with enhanced flexibility. Chemical and physical perturbants reveal cooperative unfolding transitions, with evidence of significant population of intermediate species in equilibrium, structurally akin to those transiently observed in IFABP. The recognition by the natural ligand oleic acid exerts a mild stabilizing effect, being of a greater magnitude than that found for IFABP. In summary, Δ98Δ adopts a monomeric state with a compact core and a loose periphery, thus pointing to the nonintuitive notion that the integrity of the β-barrel can indeed be compromised with no consequence on the ability to attain a native-like and functional fold. PMID:19309727

Equation of state and phase diagram of Fe-16Si alloy as a candidate component of Earth's core

NASA Astrophysics Data System (ADS)

Fischer, Rebecca A.; Campbell, Andrew J.; Caracas, Razvan; Reaman, Daniel M.; Dera, Przymyslaw; Prakapenka, Vitali B.

2012-12-01

The outer core of the Earth contains several weight percent of one or more unknown light elements, which may include silicon. Therefore it is critical to understand the high pressure-temperature properties and behavior of an iron-silicon alloy with a geophysically relevant composition (16 wt% silicon). We experimentally determined the melting curve, subsolidus phase diagram, and equations of state of all phases of Fe-16 wt%Si to 140 GPa, finding a conversion from the D03 crystal structure to a B2+hcp mixture at high pressures. The melting curve implies that 3520 K is a minimum temperature for the Earth's outer core, if it consists solely of Fe-Si alloy, and that the eutectic composition in the Fe-Si system is less than 16 wt% silicon at core-mantle boundary conditions. Comparing our new equation of state to that of iron and the density of the core, we find that for an Fe-Ni-Si outer core, 11.3±1.5 wt% silicon would be required to match the core's observed density at the core-mantle boundary. We have also performed first-principles calculations of the equations of state of Fe3Si with the D03 structure, hcp iron, and FeSi with the B2 structure using density-functional theory.

CORE SHAPES AND ORIENTATIONS OF CORE-SÉRSIC GALAXIES

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

Dullo, Bililign T.; Graham, Alister W., E-mail: Bdullo@astro.swin.edu.au

2015-01-01

The inner and outer shapes and orientations of core-Sérsic galaxies may hold important clues to their formation and evolution. We have therefore measured the central and outer ellipticities and position angles for a sample of 24 core-Sérsic galaxies using archival Hubble Space Telescope (HST) images and data. By selecting galaxies with core-Sérsic break radii R{sub b} —a measure of the size of their partially depleted core—that are ≳ 0.''2, we find that the ellipticities and position angles are quite robust against HST seeing. For the bulk of the galaxies, there is a good agreement between the ellipticities and position anglesmore » at the break radii and the average outer ellipticities and position angles determined over R {sub e}/2 < R < R {sub e}, where R {sub e} is the spheroids' effective half light radius. However there are some interesting differences. We find a median ''inner'' ellipticity at R{sub b} of ε{sub med} = 0.13 ± 0.01, rounder than the median ellipticity of the ''outer'' regions ε{sub med} = 0.20 ± 0.01, which is thought to reflect the influence of the central supermassive black hole at small radii. In addition, for the first time we find a trend, albeit weak (2σ significance), such that galaxies with larger (stellar deficit-to-supermassive black hole) mass ratios—thought to be a measure of the number of major dry merger events—tend to have rounder inner and outer isophotes, suggesting a connection between the galaxy shapes and their merger histories. We show that this finding is not simply reflecting the well known result that more luminous galaxies are rounder, but it is no doubt related.« less

Nuclear reactor I

DOEpatents

Ference, Edward W.; Houtman, John L.; Waldby, Robert N.

1977-01-01

A nuclear reactor, particularly a liquid-metal breeder reactor whose upper internals include provision for channeling the liquid metal flowing from the core-component assemblies to the outlet plenum in vertical paths in direction generally along the direction of the respective assemblies. The metal is channeled by chimneys, each secured to, and extending from, a grid through whose openings the metal emitted by a plurality of core-component assemblies encompassed by the grid flows. To reduce the stresses resulting from structural interaction, or the transmissive of thermal strains due to large temperature differences in the liquid metal emitted from neighboring core-component assemblies, throughout the chimneys and the other components of the upper internals, the grids and the chimneys are supported from the heat plate and the core barrel by support columns (double portal support) which are secured to the head plate at the top and to a member, which supports the grids and is keyed to the core barrel, at the bottom. In addition to being restrained from lateral flow by the chimneys, the liquid metal is also restrained from flowing laterally by a peripheral seal around the top of the core. This seal limits the flow rate of liquid metal, which may be sharply cooled during a scram, to the outlet nozzles. The chimneys and the grids are formed of a highly-refractory, high corrosion-resistant nickel-chromium-iron alloy which can withstand the stresses produced by temperature differences in the liquid metal. The chimneys are supported by pairs of plates, each pair held together by hollow stubs coaxial with, and encircling, the chimneys. The plates and stubs are a welded structure but, in the interest of economy, are composed of stainless steel which is not weld compatible with the refractory metal. The chimneys and stubs are secured together by shells of another nickel-chromium-iron alloy which is weld compatible with, and is welded to, the stubs and has about the same coefficient of expansion as the highly-refractory, high corrosion-resistant alloy.

Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel. Part 2; 6-Ply In-Autoclave Facesheets

NASA Technical Reports Server (NTRS)

Pineda, Evan J.; Meyers, David E.; Kosareo, Daniel N.; Zalewski, Bart F.; Dixon, Genevieve D.

2013-01-01

Four honeycomb sandwich panel types, representing 1/16th arc segments of a 10-m diameter barrel section of the Heavy Lift Launch Vehicle (HLLV), were manufactured and tested under the NASA Composites for Exploration program and the NASA Constellation Ares V program. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.000 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: in-autoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3- by 5-ft panels were cut from the 1/16th barrel sections. These panels were tested under compressive loading at the NASA Langley Research Center (LaRC). Furthermore, linear eigenvalue and geometrically nonlinear finite element analyses were performed to predict the compressive response of each 3- by 5-ft panel. This manuscript summarizes the experimental and analytical modeling efforts pertaining to the panels composed of 6-ply, IM7/977-3 facesheets (referred to as Panels B-1 and B-2). To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yield good qualitative and quantitative predictions. Additionally, it was correctly predicted that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber angle misalignments, and three-dimensional (3-D) effects on the compressive response of the panel.

Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel Part 1: 8-Ply In-Autoclave Facesheets. Part 1; 8-Ply In-Autoclave Facesheets

NASA Technical Reports Server (NTRS)

Myers, David E.; Pineda, Evan J.; Zalewski, Bart F.; Kosareo, Daniel N.; Kellas, Sotiris

2013-01-01

Four honeycomb sandwich panels, representing 1/16th arc segments of a 10-m diameter barrel section of the heavy lift launch vehicle, were manufactured under the NASA Composites for Exploration program and the NASA Space Launch Systems program. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.000 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: inautoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3.00- by 5.00-ft panels were cut from the 1/16th barrel sections. These panels were tested under compressive loading at the NASA Langley Research Center. Furthermore, linear eigenvalue and geometrically nonlinear finite element analysis was performed to predict the compressive response of the 3.00- by 5.00-ft panels. This manuscript summarizes the experimental and analytical modeling efforts pertaining to the panel composed of 8-ply, IM7/977-3 facesheets (referred to Panel A). To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yield good qualitative and quantitative predictions. Additionally, it was predicted correctly that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber misalignments, and three-dimensional (3 D) effects on the compressive response of the panel.

Structural analysis of Bacillus pumilus phenolic acid decarboxylase, a lipocalin-fold enzyme

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

Matte, Allan; Grosse, Stephan; Bergeron, Hélène

The decarboxylation of phenolic acids, including ferulic and p-coumaric acids, to their corresponding vinyl derivatives is of importance in the flavoring and polymer industries. Here, the crystal structure of phenolic acid decarboxylase (PAD) from Bacillus pumilus strain UI-670 is reported. The enzyme is a 161-residue polypeptide that forms dimers both in the crystal and in solution. The structure of PAD as determined by X-ray crystallography revealed a -barrel structure and two -helices, with a cleft formed at one edge of the barrel. The PAD structure resembles those of the lipocalin-fold proteins, which often bind hydrophobic ligands. Superposition of structurally relatedmore » proteins bound to their cognate ligands shows that they and PAD bind their ligands in a conserved location within the -barrel. Analysis of the residue-conservation pattern for PAD-related sequences mapped onto the PAD structure reveals that the conservation mainly includes residues found within the hydrophobic core of the protein, defining a common lipocalin-like fold for this enzyme family. A narrow cleft containing several conserved amino acids was observed as a structural feature and a potential ligand-binding site.« less

Permanent-magnet switched-flux machine

DOEpatents

Trzynadlowski, Andrzej M.; Qin, Ling

2010-01-12

A permanent-magnet switched-flux (PMSF) device has a ferromagnetic outer stator mounted to a shaft about a central axis extending axially through the PMSF device. Pluralities of top and bottom stator poles are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the ferromagnetic outer stator. A ferromagnetic inner rotor is coupled to the shaft and has i) a rotor core having a core axis co-axial with the central axis; and ii) first and second discs having respective outer edges with first and second pluralities of permanent magnets (PMs) mounted in first and second circles, radially outwardly from the rotor core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.

The Effect of Inner Core Translation on Outer Core Flow and the Geomagnetic Field

NASA Astrophysics Data System (ADS)

Mound, J. E.; Davies, C. J.; Silva, L.

2015-12-01

Bulk translation of the inner core has been proposed to explain quasi-hemispheric patterns of seismic heterogeneity. Such a translation would result in differential melting and freezing at the inner core boundary (ICB) and hence a heterogeneous pattern of buoyancy flux that could influence convection in the outer core. This heterogeneous flux at the ICB will tend to promote upwelling on the trailing hemisphere, where enhanced inner core growth results in increased latent heat and light element release, and inhibit upwelling on the leading hemisphere, where melting of the inner core occurs. If this difference in convective driving between the two hemispheres propagated across the thickness of the outer core, then flows near the surface of the core could be linked to the ICB heterogeneity and result in a hemispheric imbalance in the geomagnetic field. We have investigated the influence of such ICB boundary conditions on core flows and magnetic field structure in numerical geodynamo models and analysed the resultant hemispheric imbalance relative to the hemispheric structure in models constructed from observations of Earth's field. Inner core translation at rates consistent with estimates for the Earth produce a strong hemispheric bias in the field, one that should be readily apparent in averages of the field over tens of thousands of years. Current models of the field over the Holocene may be able to rule out the most extreme ICB forcing scenarios, but more information on the dynamic structure of the field over these time scales will be needed to adequately test all cases.

TprC/D (Tp0117/131), a trimeric, pore-forming rare outer membrane protein of Treponema pallidum, has a bipartite domain structure.

PubMed

Anand, Arvind; Luthra, Amit; Dunham-Ems, Star; Caimano, Melissa J; Karanian, Carson; LeDoyt, Morgan; Cruz, Adriana R; Salazar, Juan C; Radolf, Justin D

2012-05-01

Identification of Treponema pallidum rare outer membrane proteins (OMPs) has been a longstanding objective of syphilis researchers. We recently developed a consensus computational framework that employs a battery of cellular localization and topological prediction tools to generate ranked clusters of candidate rare OMPs (D. L. Cox et al., Infect. Immun. 78:5178-5194, 2010). TP0117/TP0131 (TprC/D), a member of the T. pallidum repeat (Tpr) family, was a highly ranked candidate. Circular dichroism, heat modifiability by SDS-PAGE, Triton X-114 phase partitioning, and liposome incorporation confirmed that full-length, recombinant TprC (TprC(Fl)) forms a β-barrel capable of integrating into lipid bilayers. Moreover, TprC(Fl) increased efflux of terbium-dipicolinic acid complex from large unilamellar vesicles and migrated as a trimer by blue-native PAGE. We found that in T. pallidum, TprC is heat modifiable, trimeric, expressed in low abundance, and, based on proteinase K accessibility and opsonophagocytosis assays, surface exposed. From these collective data, we conclude that TprC is a bona fide rare OMP as well as a functional ortholog of Escherichia coli OmpF. We also discovered that TprC has a bipartite architecture consisting of a soluble N-terminal portion (TprC(N)), presumably periplasmic and bound directly or indirectly to peptidoglycan, and a C-terminal β-barrel (TprC(C)). Syphilitic rabbits generate antibodies exclusively against TprC(C), while secondary syphilis patients fail to mount a detectable antibody response against either domain. The syphilis spirochete appears to have resolved a fundamental dilemma arising from its extracellular lifestyle, namely, how to enhance OM permeability without increasing its vulnerability to the antibody-mediated defenses of its natural human host.

The Initial Physical Conditions of Kepler-36 b and c

NASA Astrophysics Data System (ADS)

Owen, James E.; Morton, Timothy. D.

2016-03-01

The Kepler-36 planetary system consists of two exoplanets at similar separations (0.115 and 0.128 au), which have dramatically different densities. The inner planet has a density consistent with an Earth-like composition, while the outer planet is extremely low density, such that it must contain a voluminous H/He envelope. Such a density difference would pose a problem for any formation mechanism if their current densities were representative of their composition at formation. However, both planets are at close enough separations to have undergone significant evaporation in the past. We constrain the core mass, core composition, initial envelope mass, and initial cooling time of each planet using evaporation models conditioned on their present-day masses and radii, as inferred from Kepler photometry and transit timing analysis. The inner planet is consistent with being an evaporatively stripped core, while the outer planet has retained some of its initial envelope due to its higher core mass. Therefore, both planets could have had a similar formation pathway, with the inner planet having an initial envelope-mass fraction of ≲10% and core mass of ˜4.4 M⊕, while the outer had an initial envelope-mass fraction of the order of 15%-30% and core mass ˜7.3 M⊕. Finally, our results indicate that the outer planet had a long (≳30 Myr) initial cooling time, much longer than would naively be predicted from simple timescale arguments. The long initial cooling time could be evidence for a dramatic early cooling episode such as the recently proposed “boil-off” process.

GRAVITATIONAL ACCRETION OF PARTICLES ONTO MOONLETS EMBEDDED IN SATURN's RINGS

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

Yasui, Yuki; Ohtsuki, Keiji; Daisaka, Hiroshi, E-mail: y.yasui@whale.kobe-u.ac.jp, E-mail: ohtsuki@tiger.kobe-u.ac.jp

2014-12-20

Using a local N-body simulation, we examine gravitational accretion of ring particles onto moonlet cores in Saturn's rings. We find that gravitational accretion of particles onto moonlet cores is unlikely to occur in the C ring and probably difficult in the inner B ring as well provided that the cores are rigid water ice. Dependence of particle accretion on ring thickness changes when the radial distance from the planet and/or the density of particles is varied: the former determines the size of the core's Hill radius relative to its physical size, while the latter changes the effect of self-gravity ofmore » accreted particles. We find that particle accretion onto high-latitude regions of the core surface can occur even if the rings' vertical thickness is much smaller than the core radius, although redistribution of particles onto the high-latitude regions would not be perfectly efficient in outer regions of the rings such as the outer A ring, where the size of the core's Hill sphere in the vertical direction is significantly larger than the core's physical radius. Our results suggest that large boulders recently inferred from observations of transparent holes in the C ring are not formed locally by gravitational accretion, while propeller moonlets in the A ring would be gravitational aggregates formed by particle accretion onto dense cores. Our results also imply that the main bodies of small satellites near the outer edge of Saturn's rings may have been formed in rather thin rings.« less

Lateral restraint assembly for reactor core

DOEpatents

Gorholt, Wilhelm; Luci, Raymond K.

1986-01-01

A restraint assembly for use in restraining lateral movement of a reactor core relative to a reactor vessel wherein a plurality of restraint assemblies are interposed between the reactor core and the reactor vessel in circumferentially spaced relation about the core. Each lateral restraint assembly includes a face plate urged against the outer periphery of the core by a plurality of compression springs which enable radial preloading of outer reflector blocks about the core and resist low-level lateral motion of the core. A fixed radial key member cooperates with each face plate in a manner enabling vertical movement of the face plate relative to the key member but restraining movement of the face plate transverse to the key member in a plane transverse to the center axis of the core. In this manner, the key members which have their axes transverse to or subtending acute angles with the direction of a high energy force tending to move the core laterally relative to the reactor vessel restrain such lateral movement.

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).

Identification and Characterization of the Major Porin of Desulfovibrio vulgaris Hildenborough

DOE PAGES

Zeng, Lucy; Wooton, Etsuko; Stahl, David A.; ...

2017-09-05

Due in large part to their ability to facilitate the diffusion of a diverse range of solutes across the outer membrane (OM) of Gram-negative bacteria, the porins represent one of the most prominent and important bacterial membrane protein superfamilies. Notably, for the Gram-negative bacterium Desulfovibrio vulgaris Hildenborough, a model organism for studies of sulfate-reducing bacteria, no genes for porins have been identified or proposed in its annotated genome. Results from initial biochemical studies suggested that the product of the DVU0799 gene, which is one of the most abundant proteins of the D. vulgaris Hildenborough OM and purified as a homotrimericmore » complex, was a strong porin candidate. To investigate this possibility, this protein was further characterized biochemically and biophysically. Structural analyses via electron microscopy of negatively stained protein identified trimeric particles with stain-filled depressions and structural modeling suggested a β-barrel structure for the monomer, motifs common among the known porins. Functional studies were performed in which crude OM preparations or purified DVU0799 was reconstituted into proteoliposomes and the proteoliposomes were examined for permeability against a series of test solutes. The results obtained establish DVU0799 to be a pore-forming protein with permeability properties similar to those observed for classical bacterial porins, such as those of Escherichia coli. Taken together, these findings identify this highly abundant OM protein to be the major porin of D. vulgaris Hildenborough. Classification of DVU0799 in this model organism expands the database of functionally characterized porins and may also extend the range over which sequence analysis strategies can be used to identify porins in other bacterial genomes. Porins are membrane proteins that form transmembrane pores for the passive transport of small molecules across the outer membranes of Gram-negative bacteria. The present study identified and characterized the major porin of the model sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough, observing its preference for anionic sugars over neutral ones. Its predicted architecture appears to be novel for a classical porin, as its core β-barrel structure is of a type typically found in solute-specific channels. Broader use of the methods employed here, such as assays for channel permeability and electron microscopy of purified samples, is expected to help expand the database of confirmed porin sequences and improve the range over which sequence analysis-based strategies can be used to identify porins in other Gram-negative bacteria. Functional characterization of these critical gatekeeping proteins from divergent Desulfovibrio species should offer an improved understanding of the physiological features that determine their habitat range and supporting activities.« less

Identification and Characterization of the Major Porin of Desulfovibrio vulgaris Hildenborough

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

Zeng, Lucy; Wooton, Etsuko; Stahl, David A.

Due in large part to their ability to facilitate the diffusion of a diverse range of solutes across the outer membrane (OM) of Gram-negative bacteria, the porins represent one of the most prominent and important bacterial membrane protein superfamilies. Notably, for the Gram-negative bacterium Desulfovibrio vulgaris Hildenborough, a model organism for studies of sulfate-reducing bacteria, no genes for porins have been identified or proposed in its annotated genome. Results from initial biochemical studies suggested that the product of the DVU0799 gene, which is one of the most abundant proteins of the D. vulgaris Hildenborough OM and purified as a homotrimericmore » complex, was a strong porin candidate. To investigate this possibility, this protein was further characterized biochemically and biophysically. Structural analyses via electron microscopy of negatively stained protein identified trimeric particles with stain-filled depressions and structural modeling suggested a β-barrel structure for the monomer, motifs common among the known porins. Functional studies were performed in which crude OM preparations or purified DVU0799 was reconstituted into proteoliposomes and the proteoliposomes were examined for permeability against a series of test solutes. The results obtained establish DVU0799 to be a pore-forming protein with permeability properties similar to those observed for classical bacterial porins, such as those of Escherichia coli. Taken together, these findings identify this highly abundant OM protein to be the major porin of D. vulgaris Hildenborough. Classification of DVU0799 in this model organism expands the database of functionally characterized porins and may also extend the range over which sequence analysis strategies can be used to identify porins in other bacterial genomes. Porins are membrane proteins that form transmembrane pores for the passive transport of small molecules across the outer membranes of Gram-negative bacteria. The present study identified and characterized the major porin of the model sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough, observing its preference for anionic sugars over neutral ones. Its predicted architecture appears to be novel for a classical porin, as its core β-barrel structure is of a type typically found in solute-specific channels. Broader use of the methods employed here, such as assays for channel permeability and electron microscopy of purified samples, is expected to help expand the database of confirmed porin sequences and improve the range over which sequence analysis-based strategies can be used to identify porins in other Gram-negative bacteria. Functional characterization of these critical gatekeeping proteins from divergent Desulfovibrio species should offer an improved understanding of the physiological features that determine their habitat range and supporting activities.« less

Stratification of earth's outermost core inferred from SmKS array data

NASA Astrophysics Data System (ADS)

Kaneshima, Satoshi; Matsuzawa, Takanori

2015-12-01

S mKS arrivals recorded by large-scale broadband seismometer arrays are analyzed to investigate the depth profile of P wave speed ( V p ) in the outermost core. The V p structure of the upper 700 km of the outer core has been determined using S mKS waves of Fiji-Tonga events recorded at stations in Europe. According to a recent outer core model (KHOMC), the V p value is 0.45 % slower at the core mantle boundary (CMB) than produced by the Preliminary Reference Earth Model (PREM), and the slow anomaly gradually diminishes to insignificant values at ˜300 km below the CMB. In this study, after verifying these KHOMC features, we show that the differential travel times measured for S mKS waves that are recorded by other large-scale arrays sampling laterally different regions are well matched by KHOMC. We also show that KHOMC precisely fits the observed relative slowness values between S2KS, S3KS, and S4KS (S mKS waves with m= 2, 3, and 4). Based on these observations, we conclude that S mKS predominantly reflect the outer core structure. Then we evaluate biases of secondary importance which may be caused by mantle heterogeneity. The KHOMC V p profile can be characterized by a significant difference in the radial V p gradient between the shallower 300 km and the deeper part of the upper 700 km of the core. The shallower part has a V p gradient of -0.0018 s -1, which is steeper by 0.0001 s -1 when compared to the deeper core presented by PREM. The steeper V p gradient anomaly of the uppermost core corresponds to a radial variation in the pressure derivative of the bulk modulus, K '= d K/ d P. The K ' value is 3.7, which is larger by about 0.2 than that of the deeper core. The radial variation in K ' is too large to have a purely thermal origin, according to recent ab initio calculations on liquid iron alloys, and thus requires a thick and compositionally stratified layering at the outermost outer core.

Thermal Equation of State of Iron: Constraint on the Density Deficit of Earth's Core

NASA Astrophysics Data System (ADS)

Fei, Y.; Murphy, C. A.; Shibazaki, Y.; Huang, H.

2013-12-01

The seismically inferred densities of Earth's solid inner core and the liquid outer core are smaller than the measured densities of solid hcp-iron and liquid iron, respectively. The inner core density deficit is significantly smaller than the outer core density deficit, implying different amounts and/or identities of light-elements incorporated in the inner and outer cores. Accurate measurements of the thermal equation-of-state of iron over a wide pressure and temperature range are required to precisely quantify the core density deficits, which are essential for developing a quantitative composition model for the core. The challenge has been evaluating the experimental uncertainties related to the choice of pressure scales and the sample environment, such as hydrostaticity at multi-megabar pressures and extreme temperatures. We have conducted high-pressure experiments on iron in MgO, NaCl, and Ne pressure media and obtained in-situ X-ray diffraction data up to 200 GPa at room temperature. Using inter-calibrated pressure scales including the MgO, NaCl, Ne, and Pt scales, we have produced a consistent compression curve of hcp-Fe at room temperature. We have also performed laser-heated diamond-anvil cell experiments on both Fe and Pt in a Ne pressure medium. The experiment was designed to quantitatively compare the thermal expansion of Fe and Pt in the same sample environment using Ne as the pressure medium. The thermal expansion data of hcp-Fe at high pressure were derived based on the thermal equation of state of Pt. Using the 300-K isothermal compression curve of iron derived from our static experiments as a constraint, we have developed a thermal equation of state of hcp-Fe that is consistent with the static P-V-T data of iron and also reproduces the shock wave Hugoniot data for pure iron. The thermodynamic model, based on both static and dynamic data, is further used to calculate the density and bulk sound velocity of liquid iron. Our results define the solid inner core and liquid outer core density deficits, which can serve as the basis for any core composition models.

Submersible sodium pump

DOEpatents

Brynsvold, Glen V.; Lopez, John T.; Olich, Eugene E.; West, Calvin W.

1989-01-01

An electromagnetic submerged pump has an outer cylindrical stator with an inner cylindrical conductive core for the submerged pumping of sodium in the cylindrical interstitial volume defined between the stator and core. The cylindrical interstitial volume is typically vertically oriented, and defines an inlet at the bottom and an outlet at the top. The outer stator generates upwardly conveyed toroidal magnetic fields, which fields convey preferably from the bottom of the pump to the top of the pump liquid sodium in the cold leg of a sodium cooled nuclear reactor. The outer cylindrical stator has a vertically disposed duct surrounded by alternately stacked layers of coil units and laminates.

Submersible sodium pump

DOEpatents

Brynsvold, G.V.; Lopez, J.T.; Olich, E.E.; West, C.W.

1989-11-21

An electromagnetic submerged pump has an outer cylindrical stator with an inner cylindrical conductive core for the submerged pumping of sodium in the cylindrical interstitial volume defined between the stator and core. The cylindrical interstitial volume is typically vertically oriented, and defines an inlet at the bottom and an outlet at the top. The outer stator generates upwardly conveyed toroidal magnetic fields, which fields convey preferably from the bottom of the pump to the top of the pump liquid sodium in the cold leg of a sodium cooled nuclear reactor. The outer cylindrical stator has a vertically disposed duct surrounded by alternately stacked layers of coil units and laminates. 14 figs.

Uptake of PAHs by cabbage root and leaf in vegetable plots near a large coking manufacturer and associations with PAHs in cabbage core.

PubMed

Xiong, GuanNan; Zhang, YunHui; Duan, YongHong; Cai, ChuanYang; Wang, Xin; Li, JingYa; Tao, Shu; Liu, WenXin

2017-08-01

Samples of ambient air (including gaseous and particulate phases), dust fall, surface soil, rhizosphere soil, core (edible part), outer leaf, and root of cabbage from eight vegetable plots near a large coking manufacturer were collected during the harvest period. Concentrations, compositions, and distributions of parent PAHs in different samples were determined. Our results indicated that most of the parent PAHs in air occurred in the gaseous phase, dominated by low molecular weight (LMW) species with two to three rings. Specific isomeric ratios and principal component analysis were employed to preliminarily identify the local sources of parent PAHs emitted. The main emission sources of parent PAHs could be apportioned as a mixture of coal combustion, coking production, and traffic tailing gas. PAH components with two to four rings were prevailing in dust fall, surface soil, and rhizosphere soil. Concentrations of PAHs in surface soil exhibited a significant positive correlation with topsoil TOC fractions. Compositional profiles in outer leaf and core of cabbage, dominated by LMW species, were similar to those in the local air. Overall, the order of parent PAH concentration in cabbage was outer leaf > root > core. Partial correlation analysis and multivariate linear stepwise regression revealed that PAH concentrations in cabbage core were closely associated with PAHs present both in root and in outer leaf, namely, affected by adsorption, then absorption, and translocation of PAHs from rhizosphere soil and ambient air, respectively.

Ag@ZnO core-shell nanoparticles study by first principle: The structural, magnetic and optical properties

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

Cheng, Hai-Xia; Wang, Xiao-Xu; Beijing Computing Center, Beijing 100094

Ag@ZnO core-shell nanoparticles of around 72 atoms have been investigated by the density functional theory, revealing proving for the first time that the core-shell structure exhibits a shrinkage phenomenon from outer shell in agreement with the other studies in literatures. Our calculations predict that the Ag@ZnO core-shell structure is a ferromagnetic spin polarized state, and the magnetism mainly stems from the spin splitting of 2p electrons of O atoms. In addition, the total and partial DOS of Ag@ZnO indicate that the nanostructure is a half-metallic nanoparticle and has the characters of the p-type semiconductor. Furthermore, the optical properties calculations showmore » that the absorption edge of Ag@ZnO have a red shift and good photocatalysis compare to that of the bulk ZnO. These results of the Ag@ZnO core-shell structure obtain a well agreement with the experimental measurement. - Graphical abstract: Geometric structure of (a) Ag@ZnO core-shell nanostructure; (b) the core of Ag; (c) the shell of ZnO The core-shell nanoparticle Ag@ZnO contains Ag inner core of radius of 4 Å and ZnO outer shell with thickness of 2 Å. Ag@ZnO core-shell nanoparticles of around 72 atoms have been proved for the first time that the core-shell structure exhibit a shrinkage phenomenon from outer shell. Our calculations predict that the Ag@ZnO core-shell structure is a half-metallic nanoparticle and has the characters of the p-type semiconductor. The absorption edge of Ag@ZnO have a red shift and get good photo-catalysis compare to that of the bulk ZnO.« less

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

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.

Size-dependent forced PEG partitioning into channels: VDAC, OmpC, and α-hemolysin

DOE PAGES

Aksoyoglu, M. Alphan; Podgornik, Rudolf; Bezrukov, Sergey M.; ...

2016-07-27

Nonideal polymer mixtures of PEGs of different molecular weights partition differently into nanosize protein channels. Here, we assess the validity of the recently proposed theoretical approach of forced partitioning for three structurally different beta-barrel channels: voltage-dependent anion channel from outer mitochondrial membrane VDAC, bacterial porin OmpC (outer membrane protein C), and bacterial channel-forming toxin alpha-hemolysin. Our interpretation is based on the idea that relatively less-penetrating polymers push the more easily penetrating ones into nanosize channels in excess of their bath concentration. Comparison of the theory with experiments is excellent for VDAC. Polymer partitioning data for the other two channels aremore » consistent with theory if additional assumptions regarding the energy penalty of pore penetration are included. In conclusion, the obtained results demonstrate that the general concept of "polymers pushing polymers" is helpful in understanding and quantification of concrete examples of size-dependent forced partitioning of polymers into protein nanopores.« less

Size-dependent forced PEG partitioning into channels: VDAC, OmpC, and α-hemolysin

PubMed Central

Aksoyoglu, M. Alphan; Podgornik, Rudolf; Bezrukov, Sergey M.; Gurnev, Philip A.; Muthukumar, Murugappan; Parsegian, V. Adrian

2016-01-01

Nonideal polymer mixtures of PEGs of different molecular weights partition differently into nanosize protein channels. Here, we assess the validity of the recently proposed theoretical approach of forced partitioning for three structurally different β-barrel channels: voltage-dependent anion channel from outer mitochondrial membrane VDAC, bacterial porin OmpC (outer membrane protein C), and bacterial channel-forming toxin α-hemolysin. Our interpretation is based on the idea that relatively less-penetrating polymers push the more easily penetrating ones into nanosize channels in excess of their bath concentration. Comparison of the theory with experiments is excellent for VDAC. Polymer partitioning data for the other two channels are consistent with theory if additional assumptions regarding the energy penalty of pore penetration are included. The obtained results demonstrate that the general concept of “polymers pushing polymers” is helpful in understanding and quantification of concrete examples of size-dependent forced partitioning of polymers into protein nanopores. PMID:27466408

LPT. EBOR (TAN646) interior, installing reactor in STF pool ("vault"). ...

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

LPT. EBOR (TAN-646) interior, installing reactor in STF pool ("vault"). Pressure vessel shows core barrel and outlet nozzle (next to man below) to inner duct weld, which is prepared and in position for stress relieving. Camera facing southeast. Photographer: Comiskey. Date: January 20, 1965. INEEL negative no. 65-239 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

Thermal barriers for compartments

DOEpatents

Kreutzer, Cory J.; Lustbader, Jason A.

2017-10-17

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

A seismologically consistent compositional model of Earth's core.

PubMed

Badro, James; Côté, Alexander S; Brodholt, John P

2014-05-27

Earth's core is less dense than iron, and therefore it must contain "light elements," such as S, Si, O, or C. We use ab initio molecular dynamics to calculate the density and bulk sound velocity in liquid metal alloys at the pressure and temperature conditions of Earth's outer core. We compare the velocity and density for any composition in the (Fe-Ni, C, O, Si, S) system to radial seismological models and find a range of compositional models that fit the seismological data. We find no oxygen-free composition that fits the seismological data, and therefore our results indicate that oxygen is always required in the outer core. An oxygen-rich core is a strong indication of high-pressure and high-temperature conditions of core differentiation in a deep magma ocean with an FeO concentration (oxygen fugacity) higher than that of the present-day mantle.

A seismologically consistent compositional model of Earth’s core

PubMed Central

Badro, James; Côté, Alexander S.; Brodholt, John P.

2014-01-01

Earth’s core is less dense than iron, and therefore it must contain “light elements,” such as S, Si, O, or C. We use ab initio molecular dynamics to calculate the density and bulk sound velocity in liquid metal alloys at the pressure and temperature conditions of Earth's outer core. We compare the velocity and density for any composition in the (Fe–Ni, C, O, Si, S) system to radial seismological models and find a range of compositional models that fit the seismological data. We find no oxygen-free composition that fits the seismological data, and therefore our results indicate that oxygen is always required in the outer core. An oxygen-rich core is a strong indication of high-pressure and high-temperature conditions of core differentiation in a deep magma ocean with an FeO concentration (oxygen fugacity) higher than that of the present-day mantle. PMID:24821817

Pole-phase modulated toroidal winding for an induction machine

DOEpatents

Miller, John Michael; Ostovic, Vlado

1999-11-02

A stator (10) for an induction machine for a vehicle has a cylindrical core (12) with inner and outer slots (26, 28) extending longitudinally along the inner and outer peripheries between the end faces (22, 24). Each outer slot is associated with several adjacent inner slots. A plurality of toroidal coils (14) are wound about the core and laid in the inner and outer slots. Each coil occupies a single inner slot and is laid in the associated outer slot thereby minimizing the distance the coil extends from the end faces and minimizing the length of the induction machine. The toroidal coils are configured for an arbitrary pole phase modulation wherein the coils are configured with variable numbers of phases and poles for providing maximum torque for cranking and switchable to a another phase and pole configuration for alternator operation. An adaptor ring (36) circumferentially positioned about the stator improves mechanical strength, and provides a coolant channel manifold (34) for removing heat produced in stator windings during operation.

Membrane Remodeling by the Double-Barrel Scaffolding Protein of Poxvirus

PubMed Central

Hijnen, Marcel; Schult, Philipp; Pettikiriarachchi, Anne; Mitra, Alok K.; Coulibaly, Fasséli

2011-01-01

In contrast to most enveloped viruses, poxviruses produce infectious particles that do not acquire their internal lipid membrane by budding through cellular compartments. Instead, poxvirus immature particles are generated from atypical crescent-shaped precursors whose architecture and composition remain contentious. Here we describe the 2.6 Å crystal structure of vaccinia virus D13, a key structural component of the outer scaffold of viral crescents. D13 folds into two jellyrolls decorated by a head domain of novel fold. It assembles into trimers that are homologous to the double-barrel capsid proteins of adenovirus and lipid-containing icosahedral viruses. We show that, when tethered onto artificial membranes, D13 forms a honeycomb lattice and assembly products structurally similar to the viral crescents and immature particles. The architecture of the D13 honeycomb lattice and the lipid-remodeling abilities of D13 support a model of assembly that exhibits similarities with the giant mimivirus. Overall, these findings establish that the first committed step of poxvirus morphogenesis utilizes an ancestral lipid-remodeling strategy common to icosahedral DNA viruses infecting all kingdoms of life. Furthermore, D13 is the target of rifampicin and its structure will aid the development of poxvirus assembly inhibitors. PMID:21931553

COMPOSITE NEUTRONIC REACTOR

DOEpatents

Menke, J.R.

1963-06-11

This patent relates to a reactor having a core which comprises an inner active region and an outer active region, each region separately having a k effective less than one and a k infinity greater than one. The inner and outer regions in combination have a k effective at least equal to one and each region contributes substantially to the k effective of the reactor core. The inner region has a low moderator to fuel ratio such that the majority of fissions occurring therein are induced by neutrons having energies greater than thermal. The outer region has a high moderator to fuel ratio such that the majority of fissions occurring therein are induced by thermal neutrons. (AEC)

Physical and Electronic Isolation of Carbon Nanotube Conductors

NASA Technical Reports Server (NTRS)

OKeeffe, James; Biegel, Bryan (Technical Monitor)

2001-01-01

Multi-walled nanotubes are proposed as a method to electrically and physically isolate nanoscale conductors from their surroundings. We use tight binding (TB) and density functional theory (DFT) to simulate the effects of an external electric field on multi-wall nanotubes. Two categories of multi-wall nanotube are investigated, those with metallic and semiconducting outer shells. In the metallic case, simulations show that the outer wall effectively screens the inner core from an applied electric field. This offers the ability to reduce crosstalk between nanotube conductors. A semiconducting outer shell is found not to perturb an electric field incident on the inner core, thereby providing physical isolation while allowing the tube to remain electrically coupled to its surroundings.

Pressurized water reactor flow skirt apparatus

DOEpatents

Kielb, John F.; Schwirian, Richard E.; Lee, Naugab E.; Forsyth, David R.

2016-04-05

A pressurized water reactor vessel having a flow skirt formed from a perforated cylinder structure supported in the lower reactor vessel head at the outlet of the downcomer annulus, that channels the coolant flow through flow holes in the wall of the cylinder structure. The flow skirt is supported at a plurality of circumferentially spaced locations on the lower reactor vessel head that are not equally spaced or vertically aligned with the core barrel attachment points, and the flow skirt employs a unique arrangement of hole patterns that assure a substantially balanced pressure and flow of the coolant over the entire underside of the lower core support plate.

Technologies for Assessing the Geologic and Geomorphic History of Coasts

DTIC Science & Technology

1993-03-01

memory have dramatically increased the storage capacity of underwater instruments. Some can remain onsite as long as 12 months. 2. If a gage floods, data...analyzing stratigraphic data, the age relations of the rock strata, rock form and distribution, lithologies, fossil record, biopaleogeography, and...coring tube barrel 10 ft; UD samples. gravity corer) contains a piston that additional 10-ft remains stationary on the sections can be seafloor during

Changes in divertor conditions in response to changing core density with RMPs

DOE PAGES

Briesemeister, Alexis R.; Ahn, Joon -Wook; Canik, John M.; ...

2017-06-07

The effects of changes in core density on divertor electron temperature, density and heat flux when resonant magnetic perturbations (RMPs) are applied are presented, notably a reduction in RMP induced secondary radial peaks in the electron temperature profile at the target plate is observed when the core density is increased, which is consistent with modeling. RMPs is used here to indicated non-axisymmetric magnetic field perturbations, created using in-vessel control coils, which have components which has at least one but typically many resonances with the rotational transform of the plasma. RMPs are found to alter inter-ELM heat flux to the divertormore » by modifying the core plasma density. It is shown that applying RMPs reduces the core density and increases the inter-ELM heat flux to both the inner and outer targets. Using gas puffing to return the core density to the pre-RMP levels more than eliminates the increase in inter-ELM heat flux, but a broadening of the heat flux to the outer target remains. These measurements were made at a single toroidal location, but the peak in the heat flux profile was found near the outer strike point where simulations indicate little toroidal variation should exist and tangentially viewing diagnostics showed no evidence of strong asymmetries. In experiments where divertor Thomson scattering measurements were available it is shown that, local secondary peaks in the divertor electron temperature profile near the target plate are reduced as the core density is increased, while peaks in the divertor electron density profile near the target are increased. Furthermore, these trends observed in the divertor electron temperature and density are qualitatively reproduced by scanning the upstream density in EMC3-Eirene modeling. Measurements are presented showing that higher densities are needed to induce detachment of the outer strike point in a case where an increase in electron temperature, likely due to a change in MHD activity, is seen after RMPs are applied.« less

Changes in divertor conditions in response to changing core density with RMPs

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

Briesemeister, Alexis R.; Ahn, Joon -Wook; Canik, John M.

The effects of changes in core density on divertor electron temperature, density and heat flux when resonant magnetic perturbations (RMPs) are applied are presented, notably a reduction in RMP induced secondary radial peaks in the electron temperature profile at the target plate is observed when the core density is increased, which is consistent with modeling. RMPs is used here to indicated non-axisymmetric magnetic field perturbations, created using in-vessel control coils, which have components which has at least one but typically many resonances with the rotational transform of the plasma. RMPs are found to alter inter-ELM heat flux to the divertormore » by modifying the core plasma density. It is shown that applying RMPs reduces the core density and increases the inter-ELM heat flux to both the inner and outer targets. Using gas puffing to return the core density to the pre-RMP levels more than eliminates the increase in inter-ELM heat flux, but a broadening of the heat flux to the outer target remains. These measurements were made at a single toroidal location, but the peak in the heat flux profile was found near the outer strike point where simulations indicate little toroidal variation should exist and tangentially viewing diagnostics showed no evidence of strong asymmetries. In experiments where divertor Thomson scattering measurements were available it is shown that, local secondary peaks in the divertor electron temperature profile near the target plate are reduced as the core density is increased, while peaks in the divertor electron density profile near the target are increased. Furthermore, these trends observed in the divertor electron temperature and density are qualitatively reproduced by scanning the upstream density in EMC3-Eirene modeling. Measurements are presented showing that higher densities are needed to induce detachment of the outer strike point in a case where an increase in electron temperature, likely due to a change in MHD activity, is seen after RMPs are applied.« less

Equation of state and phase diagram of Fe-16Si alloy as a candidate component of Earth's core

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

Fischer, Rebecca A; Campbell, Andrew J; Caracas, Razvan

2016-07-29

The outer core of the Earth contains several weight percent of one or more unknown light elements, which may include silicon. Therefore it is critical to understand the high pressure–temperature properties and behavior of an iron–silicon alloy with a geophysically relevant composition (16 wt% silicon). We experimentally determined the melting curve, subsolidus phase diagram, and equations of state of all phases of Fe–16 wt%Si to 140 GPa, finding a conversion from the D0 3 crystal structure to a B2+hcp mixture at high pressures. The melting curve implies that 3520 K is a minimum temperature for the Earth's outer core, ifmore » it consists solely of Fe–Si alloy, and that the eutectic composition in the Fe–Si system is less than 16 wt% silicon at core–mantle boundary conditions. Comparing our new equation of state to that of iron and the density of the core, we find that for an Fe–Ni–Si outer core, 11.3±1.5 wt% silicon would be required to match the core's observed density at the core–mantle boundary. We have also performed first-principles calculations of the equations of state of Fe 3Si with the D0 3 structure, hcp iron, and FeSi with the B2 structure using density-functional theory.« less

Earth's Fiercely Cooling Core - 24 TW

NASA Astrophysics Data System (ADS)

Morgan, Jason P.; Vannucchi, Paola

2014-05-01

Earth's mantle and core are convecting planetary heat engines. The mantle convects to lose heat from slow cooling, internal radioactivity, and core heatflow across its base. Its convection generates plate tectonics, volcanism, and the loss of ~35 TW of mantle heat through Earth's surface. The core convects to lose heat from slow cooling, small amounts of internal radioactivity, and the freezing-induced growth of a compositionally denser inner core. Core convection produces the geodynamo generating Earth's geomagnetic field. The geodynamo was thought to be powered by ~4 TW of heatloss across the core-mantle boundary, a rate sustainable (cf. Gubbins et al., 2003; Nimmo, 2007) by freezing a compositionally denser inner core over the ~3 Ga that Earth is known to have had a strong geomagnetic field (cf. Tarduno, 2007). However, recent determinations of the outer core's thermal conductivity(Pozzo et al., 2012; Gomi et al., 2013) indicate that >15 TW of power should conduct down its adiabat. Conducted power is unavailable to drive thermal convection, implying that the geodynamo needs a long-lived >17 TW power source. Core cooling was thought too weak for this, based on estimates for the Clapeyron Slope for high-pressure freezing of an idealized pure-iron core. Here we show that the ~500-1000 kg/m3 seismically-inferred jump in density between the liquid outer core and solid inner core allows us to directly infer the core-freezing Clapeyron Slope for the outer core's actual composition which contains ~8±2% lighter elements (S,Si,O,Al, H,…) mixed into a Fe-Ni alloy. A PREM-like 600 kg/m3 - based Clapeyron Slope implies there has been ~774K of core cooling during the freezing and growth of the inner core, releasing ~24 TW of power during the past ~3 Ga. If so, core cooling can easily power Earth's long-lived geodynamo. Another major implication of ~24 TW heatflow across the core-mantle boundary is that the present-day mantle is strongly 'bottom-heated', and diapiric mantle plumes should dominate deep mantle upwelling.

The Klebsiella pneumoniae YfgL (BamB) lipoprotein contributes to outer membrane protein biogenesis, type-1 fimbriae expression, anti-phagocytosis, and in vivo virulence

PubMed Central

Hsieh, Pei-Fang; Hsu, Chun-Ru; Chen, Chun-Tang; Lin, Tzu-Lung; Wang, Jin-Town

2016-01-01

ABSTRACT Klebsiella pneumoniae is an opportunistic pathogen that causes several kinds of infections, including pneumonia, bacteremia, urinary tract infection and community-acquired pyogenic liver abscess (PLA). Adhesion is the critical first step in the infection process. Our previous work demonstrated that the transcellular translocation is exploited by K. pneumoniae strains to migrate from the gut flora into other tissues, resulting in systemic infections. However, the initial stages of K. pneumoniae infection remain unclear. In this study, we demonstrated that a K. pneumoniae strain deleted for yfgL (bamB) exhibited reduced adherence to and invasion of host cells; changed biogenesis of major β-barrel outer membrane proteins; decreased transcriptional expression of type-1 fimbriae; and increased susceptibility to vancomycin and erythromycin. The yfgL deletion mutant also had reduced ability to against neutrophil phagocytosis; exhibited decreased induction of host IL-6 production; and was profoundly attenuated for virulence in a K. pneumoniae model of bacteremia. Thus, the K. pneumoniae YfgL lipoprotein mediates in outer membrane proteins biogenesis and is crucial for anti-phagocytosis and survival in vivo. These data provide a new insight for K. pneumoniae attachment and such knowledge could facilitate preventive therapies or alternative therapies against K. pneumoniae. PMID:27029012

Respiratory potential in sapwood of old versus young ponderosa pine trees in the Pacific Northwest.

PubMed

Pruyn, Michele L; Gartner, Barbara L; Harmon, Mark E

2002-02-01

Our primary objective was to present and test a new technique for in vitro estimation of respiration of cores taken from old trees to determine respiratory trends in sapwood. Our secondary objective was to quantify effects of tree age and stem position on respiratory potential (rate of CO2 production of woody tissue under standardized laboratory conditions). We extracted cores from one to four vertical positions in boles of +200-, +50- and +15-year-old Pinus ponderosa Dougl. ex Laws. trees. Cores were divided into five segments corresponding to radial depths of inner bark; outer, middle and inner sapwood; and heartwood. Data suggested that core segment CO2 production was an indicator of its respiratory activity, and that potential artifacts caused by wounding and extraction were minimal. On a dry mass basis, respiratory potential of inner bark was 3-15 times greater than that of sapwood at all heights for all ages (P < 0.0001). Within sapwood at all heights and in all ages of trees, outer sapwood had a 30-60% higher respiratory potential than middle or inner sapwood (P < 0.005). Heartwood had only 2-10% of the respiratory potential of outer sapwood. For all ages of trees, sapwood rings produced in the same calendar year released over 50% more CO2 at treetops than at bases (P < 0.0001). When scaled to the whole-tree level on a sapwood volume basis, sapwood of younger trees had higher respiratory potential than sapwood of older trees. In contrast, the trend was reversed when using the outer-bark surface area of stems as a basis for comparing respiratory potential. The differences observed in respiratory potential calculated on a core dry mass, sapwood volume, or outer-bark surface area basis clearly demonstrate that the resulting trends within and among trees are determined by the way in which the data are expressed. Although these data are based on core segments rather than in vivo measurements, we conclude that the relative differences are probably valid even if the absolute differences are not.

Ejector subassembly for dual wall air drilling

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

Kolle, J.J.

1996-09-01

The dry drilling system developed for the Yucca Mountain Site Characterization Project incorporates a surface vacuum system to prevent drilling air and cuttings from contaminating the borehole wall during coring operations. As the drilling depth increases, however there is a potential for borehole contamination because of the limited volume of air which can be removed by the vacuum system. A feasibility analysis has shown that an ejector subassembly mounted in the drill string above the core barrel could significantly enhance the depth capacity of the dry drilling system. The ejector subassembly would use a portion of the air supplied tomore » the core bit to maintain a vacuum on the hole bottom. The results of a design study including performance testing of laboratory scale ejector simulator are presented here.« less

Annular core liquid-salt cooled reactor with multiple fuel and blanket zones

DOEpatents

Peterson, Per F.

2013-05-14

A liquid fluoride salt cooled, high temperature reactor having a reactor vessel with a pebble-bed reactor core. The reactor core comprises a pebble injection inlet located at a bottom end of the reactor core and a pebble defueling outlet located at a top end of the reactor core, an inner reflector, outer reflector, and an annular pebble-bed region disposed in between the inner reflector and outer reflector. The annular pebble-bed region comprises an annular channel configured for receiving pebble fuel at the pebble injection inlet, the pebble fuel comprising a combination of seed and blanket pebbles having a density lower than the coolant such that the pebbles have positive buoyancy and migrate upward in said annular pebble-bed region toward the defueling outlet. The annular pebble-bed region comprises alternating radial layers of seed pebbles and blanket pebbles.

15 CFR 241.2 - Legal standard barrels.

Code of Federal Regulations, 2010 CFR

2010-01-01

..., VEGETABLES AND OTHER DRY COMMODITIES, AND FOR CRANBERRIES § 241.2 Legal standard barrels. (a) Any barrel..., other than cranberries, in section 1 of the standard-barrel law, or any barrel or a subdivision thereof... than cranberries, or a legal subdivision thereof. No other barrel or subdivision in barrel form is a...

15 CFR 241.2 - Legal standard barrels.

Code of Federal Regulations, 2012 CFR

2012-01-01

..., VEGETABLES AND OTHER DRY COMMODITIES, AND FOR CRANBERRIES § 241.2 Legal standard barrels. (a) Any barrel..., other than cranberries, in section 1 of the standard-barrel law, or any barrel or a subdivision thereof... than cranberries, or a legal subdivision thereof. No other barrel or subdivision in barrel form is a...

15 CFR 241.2 - Legal standard barrels.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., VEGETABLES AND OTHER DRY COMMODITIES, AND FOR CRANBERRIES § 241.2 Legal standard barrels. (a) Any barrel..., other than cranberries, in section 1 of the standard-barrel law, or any barrel or a subdivision thereof... than cranberries, or a legal subdivision thereof. No other barrel or subdivision in barrel form is a...

Observation of core sensitive phases: Constraints on the velocity and attenuation profile in the vicinity of the inner-core boundary

NASA Astrophysics Data System (ADS)

Adam, J. M.-C.; Ibourichène, A.; Romanowicz, B.

2018-02-01

We measured more than three thousand differential travel-times and amplitude ratios of PKPBC , PKPBC-diff , PKPAB and PKPDF phases in the epicentral distance range [149°-171°], from high quality records of globally distributed broadband stations. In particular, this is the largest collection of differential measurements of PKPBC-diff compared to PKPDF , extending by ∼ 10 ° the epicentral distance range in which the diffracted PKPBC phase has been observed globally. We used forward modelling of waveforms using the Direct Solution Method combined with a grid-search approach to explore attenuation and P-velocity structure in the vicinity of the inner core boundary (ICB) that can explain our observations. We find that, in order to simultaneously explain differential travel times and amplitude ratios of PKPBC , PKPBC-diff with respect to PKPDF out to distances of 165 ° , while fitting PKPAB /PKPDF within measurement errors, it is necessary to introduce a ∼ 450km zone of reduced bulk quality factor (Qκ ∼ 600) at the base of the outer core, while Qκ is close to 200 in a layer ∼ 150km thick at the top of the inner core. Concurrently, the P-velocity in the last 100 km of the outer-core is on average about 0.5 % slower than in the reference model AK 135 , while it is about 0.5 % faster in the top 150 km of the inner-core, resulting in a P-velocity jump at the inner core boundary slightly higher than in model AK 135 . However, this model underpredicts PKPBC-diff /PKPDF amplitude ratios at distances larger than 165 ° . Reducing Qκ even further in the last 100 km of the outer-core (down to Qκ = 50) provides a good fit to these data but it is not compatible with measurements of PKiKP/PKPDF amplitude ratios in the distance range 120-140°. We also considered a previously assembled global collection of "M phase" data. The M phase is a large energy in the coda of the PKPBC and PKPBC-diff that is not predicted by current 1 D reference seismic models, but most likely originates at the base of the outer-core. Our preferred model predicts the presence of an M phase, but significantly underestimates its amplitude. In order to explain the large amplitude of the M-phase and that of PKPBC-diff at distances larger than 165 ° without significantly affecting PKiKP amplitudes, it seems necessary to invoke a process that would produce strong scattering for diffracted phases in the immediate vicinity of the ICB, on the outer core side. Clusters of solid particles suspended in the fluid core or topography of the ICB are possible candidates that should be explored further.

A laboratory model for solidification of Earth's core

NASA Astrophysics Data System (ADS)

Bergman, Michael I.; Macleod-Silberstein, Marget; Haskel, Michael; Chandler, Benjamin; Akpan, Nsikan

2005-11-01

To better understand the influence of rotating convection in the outer core on the solidification of the inner core we have constructed a laboratory model for solidification of Earth's core. The model consists of a 15 cm radius hemispherical acrylic tank concentric with a 5 cm radius hemispherical aluminum heat exchanger that serves as the incipient inner core onto which we freeze ice from salt water. Long exposure photographs of neutrally buoyant particles in illuminated planes suggest reduction of flow parallel to the rotation axis. Thermistors in the tank near the heat exchanger show that in experiments with rotation the temperature near the pole is lower than near the equator, unlike for control experiments without rotation or with a polymer that increases the fluid viscosity. The photographs and thermistors suggest that our observation that ice grows faster near the pole than near the equator for experiments with rotation is a result of colder water not readily convecting away from the pole. Because of the reversal of the thermal gradient, we expect faster equatorial solidification in the Earth's core. Such anisotropy in solidification has been suggested as a cause of inner core elastic (and attenuation) anisotropy, though the plausibility of this suggestion will depend on the core Nusselt number and the slope of the liquidus, and the effects of post-solidification deformation. Previous experiments on hexagonal close-packed alloys such as sea ice and zinc-tin have shown that fluid flow in the melt can result in a solidification texture transverse to the solidification direction, with the texture depending on the nature of the flow. A comparison of the visualized flow and the texture of columnar ice crystals in thin sections from these experiments confirms flow-induced transverse textures. This suggests that the convective pattern at the base of the outer core is recorded in the texture of the inner core, and that outer core convection might contribute to the complexity in the seismically inferred pattern of anisotropy in the Earth's inner core.

Equation of state fits to the lower mantle and outer core

NASA Technical Reports Server (NTRS)

Butler, R.; Anderson, D. L.

1978-01-01

The lower mantle and outer core are subjected to tests for homogeneity and adiabaticity. An earth model is used which is based on the inversion of body waves and Q-corrected normal-mode data. Homogeneous regions are found at radii between 5125 and 4825 km, 4600 and 3850 km, and 3200 and 2200 km. The lower mantle and outer core are inhomogeneous on the whole and are only homogeneous in the above local regions. Finite-strain and atomistic equations of state are fit to the homogeneous regions. The apparent convergence of the finite-strain relations is examined to judge their applicability to a given region. In some cases the observed pressure derivatives of the elastic moduli are used as additional constraints. The effect of minor deviations from adiabaticity on the extrapolations is also considered. An ensemble of zero-pressure values of the density and seismic velocities are found for these regions. The range of extrapolated values from these several approaches provides a measure of uncertainties involved.

186Os- 187Os systematics of Gorgona Island komatiites: implications for early growth of the inner core

NASA Astrophysics Data System (ADS)

Brandon, Alan D.; Walker, Richard J.; Puchtel, Igor S.; Becker, Harry; Humayun, Munir; Revillon, Sidonie

2003-02-01

The presence of coupled enrichments in 186Os/ 188Os and 187Os/ 188Os in some mantle-derived materials reflects long-term elevation of Pt/Os and Re/Os relative to the primitive upper mantle. New Os data for the 89 Ma Gorgona Island, Colombia komatiites indicate that these lavas are also variably enriched in 186Os and 187Os, with 186Os/ 188Os ranging between 0.1198397±22 and 0.1198470±38, and with γOs correspondingly ranging from +0.15 to +4.4. These data define a linear trend that converges with the previously reported linear trend generated from data for modern Hawaiian picritic lavas and a sample from the ca. 251 Ma Siberian plume, to a common component with a 186Os/ 188Os of approximately 0.119870 and γOs of +17.5. The convergence of these data to this Os isotopic composition may imply a single ubiquitous source in the Earth's interior that mixes with a variety of different mantle compositions distinguished by variations in γOs. The 187Os- and 186Os-enriched component may have been generated via early crystallization of the solid inner core and consequent increases in Pt/Os and Re/Os in the liquid outer core, with time leading to suprachondritic 186Os/ 188Os and γOs in the outer core. The presence of Os from the outer core in certain portions of the mantle would require a mechanism that could transfer Os from the outer core to the lower mantle, and thence to the surface. If this is the process that generated the isotopic enrichments in the mantle sources of these plume-derived systems, then the current understanding of solid metal-liquid metal partitioning of Pt, Re and Os requires that crystallization of the inner core began prior to 3.5 Ga. Thus, the Os isotopic data reported here provide a new source of data to better constrain the timing of inner core formation, complementing magnetic field paleo-intensity measurements as data sources that constrain models based on secular cooling of the Earth.

Constraints on the coupled thermal evolution of the Earth's core and mantle, the age of the inner core, and the origin of the 186Os/188Os “core signal” in plume-derived lavas

NASA Astrophysics Data System (ADS)

Lassiter, J. C.

2006-10-01

The possibility that some mantle plumes may carry a geochemical signature of core/mantle interaction has rightly generated considerable interest and attention in recent years. Correlated 186Os- 187Os enrichments in some plume-derived lavas (Hawaii, Gorgona, Kostomuksha) have been interpreted as deriving from an outer core with elevated Pt/Os and Re/Os ratios due to the solidification of the Earth's inner core (c.f., [A.D. Brandon, R.J. Walker, The debate over core-mantle interaction, Earth Planet. Sci. Lett. 232 (2005) 211-225.] and references therein). Conclusive identification of a "core signal" in plume-derived lavas would profoundly influence our understanding of mantle convection and evolution. This paper reevaluates the Os-isotope evidence for core/mantle interaction by examining other geochemical constraints on core/mantle interaction, geophysical constraints on the thermal evolution of the outer core, and geochemical and cosmochemical constraints on the abundance of heat-producing elements in the core. Additional study of metal/silicate and sulfide/silicate partitioning of K, Pb, and other trace elements is needed to more tightly constrain the likely starting composition of the Earth's core. However, available data suggest that the observed 186Os enrichments in Hawaiian and other plume-derived lavas are unlikely to derive from core/mantle interaction. 1) Core/mantle interaction sufficient to produce the observed 186Os enrichments would likely have significant effects on other tracers such as Pb- and W-isotopes that are not observed. 2) Significant partitioning of K or other heat-producing elements into the core would produce a "core depletion" pattern in the Silicate Earth very different from that observed. 3) In the absence of heat-producing elements in the core, core/mantle heat flow of ˜ 6-15 TW estimated from several independent geophysical constraints suggests an inner core age (< ˜ 2.5 Ga) too young for the outer core to have developed a significant 186Os enrichment. Core/mantle thermal and chemical interaction remains an important problem that warrants future research. However, Os-isotopes may have only limited utility in this area due to the relatively young age of the Earth's inner core.

NUCLEAR POWER PLANT

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

Preece, G.E.; Bell, F.R.

1963-06-26

A protective arrangement is designed for shielding the environment and for preventing the leakage of radioactive gases from a ship nuclear power plant. In this arrangement, the core has inner and outer pressure vessels and a biological shielding around the outer pressure vessel. The shielding comprises a series of steel cylindrical shells immersed in water, and its inner wall may comprise part of the outer pressure vessel. (D.L.C.)

Seismological evidence for a localized mushy zone at the Earth's inner core boundary.

PubMed

Tian, Dongdong; Wen, Lianxing

2017-08-01

Although existence of a mushy zone in the Earth's inner core has been hypothesized several decades ago, no seismic evidence has ever been reported. Based on waveform modeling of seismic compressional waves that are reflected off the Earth's inner core boundary, here we present seismic evidence for a localized 4-8 km thick zone across the inner core boundary beneath southwest Okhotsk Sea with seismic properties intermediate between those of the inner and outer core and of a mushy zone. Such a localized mushy zone is found to be surrounded by a sharp inner core boundary nearby. These seismic results suggest that, in the current thermo-compositional state of the Earth's core, the outer core composition is close to eutectic in most regions resulting in a sharp inner core boundary, but deviation from the eutectic composition exists in some localized regions resulting in a mushy zone with a thickness of 4-8 km.The existence of a mushy zone in the Earth's inner core has been suggested, but has remained unproven. Here, the authors have discovered a 4-8 km thick mushy zone at the inner core boundary beneath the Okhotsk Sea, indicating that there may be more localized mushy zones at the inner core boundary.

Technology of civil usage of composites. [in commercial aircraft structures

NASA Technical Reports Server (NTRS)

Kemp, D. E.

1977-01-01

The paper deals with the use of advanced composites in structural components of commercial aircraft. The need for testing the response of a material system to service environment is discussed along with methods for evaluating design and manufacturing aspects of a built-up structure under environmental conditions and fail-safe (damage-tolerance) evaluation of structures. Crashworthiness aspects, the fire-hazard potential, and electrical damage of composite structures are considered. Practical operational experience with commercial aircraft is reviewed for boron/epoxy foreflaps, Kevlar/epoxy fillets and fairings, graphite/epoxy spoilers, graphite/polysulfone spoilers, graphite/epoxy floor posts, boron/aluminum aft pylon skin panels, graphite/epoxy engine nose cowl outer barrels, and graphite/epoxy upper aft rudder segments.

Structure of the virulence-associated protein VapD from the intracellular pathogen Rhodococcus equi

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

Whittingham, Jean L.; Blagova, Elena V.; Finn, Ciaran E.

2014-08-01

VapD is one of a set of highly homologous virulence-associated proteins from the multi-host pathogen Rhodococcus equi. The crystal structure reveals an eight-stranded β-barrel with a novel fold and a glycine rich ‘bald’ surface. Rhodococcus equi is a multi-host pathogen that infects a range of animals as well as immune-compromised humans. Equine and porcine isolates harbour a virulence plasmid encoding a homologous family of virulence-associated proteins associated with the capacity of R. equi to divert the normal processes of endosomal maturation, enabling bacterial survival and proliferation in alveolar macrophages. To provide a basis for probing the function of the Vapmore » proteins in virulence, the crystal structure of VapD was determined. VapD is a monomer as determined by multi-angle laser light scattering. The structure reveals an elliptical, compact eight-stranded β-barrel with a novel strand topology and pseudo-twofold symmetry, suggesting evolution from an ancestral dimer. Surface-associated octyl-β-d-glucoside molecules may provide clues to function. Circular-dichroism spectroscopic analysis suggests that the β-barrel structure is preceded by a natively disordered region at the N-terminus. Sequence comparisons indicate that the core folds of the other plasmid-encoded virulence-associated proteins from R. equi strains are similar to that of VapD. It is further shown that sequences encoding putative R. equi Vap-like proteins occur in diverse bacterial species. Finally, the functional implications of the structure are discussed in the light of the unique structural features of VapD and its partial structural similarity to other β-barrel proteins.« less

Chemical Convention in the Lunar Core from Melting Experiments on the Ironsulfur System

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

Li, J.; Liu, J.; Chen, B.

2012-03-26

By reanalyzing Apollo lunar seismograms using array-processing methods, a recent study suggests that the Moon has a solid inner core and a fluid outer core, much like the Earth. The volume fraction of the lunar inner core is 38%, compared with 4% for the Earth. The pressure at the Moon's core-mantle boundary is 4.8 GPa, and that at the ICB is 5.2 GPa. The partially molten state of the lunar core provides constraints on the thermal and chemical states of the Moon: The temperature at the inner core boundary (ICB) corresponds to the liquidus of the outer core composition, andmore » the mass fraction of the solid core allows us to infer the bulk composition of the core from an estimated thermal profile. Moreover, knowledge on the extent of core solidification can be used to evaluate the role of chemical convection in the origin of early lunar core dynamo. Sulfur is considered an antifreeze component in the lunar core. Here we investigate the melting behavior of the Fe-S system at the pressure conditions of the lunar core, using the multi-anvil apparatus and synchrotron and laboratory-based analytical methods. Our goal is to understand compositionally driven convection in the lunar core and assess its role in generating an internal magnetic field in the early history of the Moon.« less

The ab initio simulation of the Earth's core.

PubMed

Alfè, D; Gillan, M J; Vocadlo, L; Brodholt, J; Price, G D

2002-06-15

The Earth has a liquid outer and solid inner core. It is predominantly composed of Fe, alloyed with small amounts of light elements, such as S, O and Si. The detailed chemical and thermal structure of the core is poorly constrained, and it is difficult to perform experiments to establish the properties of core-forming phases at the pressures (ca. 300 GPa) and temperatures (ca. 5000-6000 K) to be found in the core. Here we present some major advances that have been made in using quantum mechanical methods to simulate the high-P/T properties of Fe alloys, which have been made possible by recent developments in high-performance computing. Specifically, we outline how we have calculated the Gibbs free energies of the crystalline and liquid forms of Fe alloys, and so conclude that the inner core of the Earth is composed of hexagonal close packed Fe containing ca. 8.5% S (or Si) and 0.2% O in equilibrium at 5600 K at the boundary between the inner and outer cores with a liquid Fe containing ca. 10% S (or Si) and 8% O.

Fluid flow near the surface of earth's outer core

NASA Technical Reports Server (NTRS)

Bloxham, Jeremy; Jackson, Andrew

1991-01-01

This review examines the recent attempts at extracting information on the pattern of fluid flow near the surface of the outer core from the geomagnetic secular variation. Maps of the fluid flow at the core surface are important as they may provide some insight into the process of the geodynamo and may place useful constraints on geodynamo models. In contrast to the case of mantle convection, only very small lateral variations in core density are necessary to drive the flow; these density variations are, by several orders of magnitude, too small to be imaged seismically; therefore, the geomagnetic secular variation is utilized to infer the flow. As substantial differences exist between maps developed by different researchers, the possible underlying reasons for these differences are examined with particular attention given to the inherent problems of nonuniqueness.

Array analyses of SmKS waves and the stratification of Earth's outermost core

NASA Astrophysics Data System (ADS)

Kaneshima, Satoshi

2018-03-01

We perform array analyses of SmKS waves in order to investigate the Vp structure of the Earth's outermost core. For earthquakes recorded by broadband seismometer networks in the world, we measure differential travel times between S3KS and S2KS, between S4KS and S3KS, and between S5KS and S3KS by array techniques. The differential times are well fit by a Vp model of the Earth's outermost core, KHOMC (Kaneshima and Helffrich, 2013). Differential slownesses of S4KS and S2KS relative to S2KS are also measured for the highest quality data. The measured slownesses, with unique sensitivity to the outer core 200-400 km below the CMB, are matched by KHOMC. These observations consolidate the evidence for the presence at the top of the outer core of a layer that has a distinctively steeper Vp gradient than the bulk of the outer core. We invert new SmKS differential time data set by a tau-p method and attempt to refine the Vp profile of KHOMC. The essential features of KHOMC are preserved after the model refinement. However, the newly estimated layer thickness is nearly 450 km, which is thicker than that of KHOMC. The Vp anomalies relative to PREM for the depths 400-800 km below the CMB are less than 0.03 km/s, consistent with the degree of agreement between different Vp models for the depth range.

Has Earth's Plate Tectonics Led to Rapid Core Cooling?

NASA Astrophysics Data System (ADS)

de Montserrat Navarro, A.; Morgan, J. P.; Vannucchi, P.; Connolly, J. A.

2016-12-01

Earth's mantle and core are convecting planetary heat engines. The mantle convects to lose heat from secular cooling, internal radioactivity, and core heatflow across its base. Its convection generates plate tectonics, volcanism, and the loss of 35 TW of mantle heat through Earth's surface. The core convects to lose heat from secular cooling, small amounts of internal radioactivity, and the freezing-induced growth of a compositionally denser inner core. Until recently, the geodynamo was thought to be powered by 4 TW of heatloss across the core-mantle boundary. More recent determinations of the outer core's thermal conductivity (Pozzo et al., 2012; Gomi et al., 2013) would imply that >15 TW of power should conduct down its adiabat. Secular core cooling has been previously thought to be too slow for this, based on estimates for the Clapeyron Slope for high-pressure freezing of an idealized pure-iron core (cf. Nimmo, 2007). The 500-1000 kg m-3 seismically-inferred jump in density between the liquid outer core and solid inner core allows a direct estimate of the Clapeyron Slope for the outer core's actual composition which contains 0.08±0.02 lighter elements (S,Si,O,Al, H,…) mixed into a Fe-Ni alloy. A PREM-like 600 kg m-3 density jump yields a Clapeyron Slope for which there has been 774K of core cooling during the freezing and growth of the inner core, cooling that has been releasing an average of 21 TW of power during the past 3 Ga. If so, core cooling could easily have powered Earth's long-lived geodynamo. Another implication is that the present-day mantle is strongly `bottom-heated', and diapiric mantle plumes should dominate deep mantle upwelling. This mode of core and mantle convection is consistent with slow, 37.5K/Ga secular cooling of Earth's mantle linked to more rapid secular cooling of the core (cf. Morgan, Rüpke, and White, 2016). Efficient plate subduction, hence plate tectonics, is a key ingredient for such rapid secular core cooling.We also show how a more complete thermodynamic version of Birch's accretional energy calculation predicts that accretion with FeNi-sinking-linked differentiation between an Earth-like mantle and core would naturally generate a core that, post-accretion, was both hotter than overlying mantle and 1000K hotter than today.

Bioorganic/inorganic hybrid composition of sponge spicules: matrix of the giant spicules and of the comitalia of the deep sea hexactinellid Monorhaphis.

PubMed

Müller, Werner E G; Wang, Xiaohong; Kropf, Klaus; Ushijima, Hiroshi; Geurtsen, Werner; Eckert, Carsten; Tahir, Muhammad Nawaz; Tremel, Wolfgang; Boreiko, Alexandra; Schlossmacher, Ute; Li, Jinhe; Schröder, Heinz C

2008-02-01

The giant basal spicules of the siliceous sponges Monorhaphis chuni and Monorhaphis intermedia (Hexactinellida) represent the largest biosilica structures on earth (up to 3m long). Here we describe the construction (lamellar organization) of these spicules and of the comitalia and highlight their organic matrix in order to understand their mechanical properties. The spicules display three distinct regions built of biosilica: (i) the outer lamellar zone (radius: >300 microm), (ii) the bulky axial cylinder (radius: <75 microm), and (iii) the central axial canal (diameter: <2 microm) with its organic axial filament. The spicules are loosely covered with a collagen net which is regularly perforated by 7-10 microm large holes; the net can be silicified. The silica layers forming the lamellar zone are approximately 5 microm thick; the central axial cylinder appears to be composed of almost solid silica which becomes porous after etching with hydrofluoric acid (HF). Dissolution of a complete spicule discloses its complex structure with distinct lamellae in the outer zone (lamellar coating) and a more resistant central part (axial barrel). Rapidly after the release of the organic coating from the lamellar zone the protein layers disintegrate to form irregular clumps/aggregates. In contrast, the proteinaceous axial barrel, hidden in the siliceous axial cylinder, is set up by rope-like filaments. Biochemical analysis revealed that the (dominant) molecule of the lamellar coating is a 27-kDa protein which displays catalytic, proteolytic activity. High resolution electron microscopic analysis showed that this protein is arranged within the lamellae and stabilizes these surfaces by palisade-like pillars. The mechanical behavior of the spicules was analyzed by a 3-point bending assay, coupled with scanning electron microscopy. The load-extension curve of the spicule shows a biphasic breakage/cracking pattern. The outer lamellar zone cracks in several distinct steps showing high resistance in concert with comparably low elasticity, while the axial cylinder breaks with high elasticity and lower stiffness. The complex bioorganic/inorganic hybrid composition and structure of the Monorhaphis spicules might provide the blueprint for the synthesis of bio-inspired material, with unusual mechanical properties (strength, stiffness) without losing the exceptional properties of optical transmission.

Pebble Bed Reactors Design Optimization Methods and their Application to the Pebble Bed Fluoride Salt Cooled High Temperature Reactor (PB-FHR)

NASA Astrophysics Data System (ADS)

Cisneros, Anselmo Tomas, Jr.

The Fluoride salt cooled High temperature Reactor (FHR) is a class of advanced nuclear reactors that combine the robust coated particle fuel form from high temperature gas cooled reactors, direct reactor auxillary cooling system (DRACS) passive decay removal of liquid metal fast reactors, and the transparent, high volumetric heat capacitance liquid fluoride salt working fluids---flibe (33%7Li2F-67%BeF)---from molten salt reactors. This combination of fuel and coolant enables FHRs to operate in a high-temperature low-pressure design space that has beneficial safety and economic implications. In 2012, UC Berkeley was charged with developing a pre-conceptual design of a commercial prototype FHR---the Pebble Bed- Fluoride Salt Cooled High Temperature Reactor (PB-FHR)---as part of the Nuclear Energy University Programs' (NEUP) integrated research project. The Mark 1 design of the PB-FHR (Mk1 PB-FHR) is 236 MWt flibe cooled pebble bed nuclear heat source that drives an open-air Brayton combine-cycle power conversion system. The PB-FHR's pebble bed consists of a 19.8% enriched uranium fuel core surrounded by an inert graphite pebble reflector that shields the outer solid graphite reflector, core barrel and reactor vessel. The fuel reaches an average burnup of 178000 MWt-d/MT. The Mk1 PB-FHR exhibits strong negative temperature reactivity feedback from the fuel, graphite moderator and the flibe coolant but a small positive temperature reactivity feedback of the inner reflector and from the outer graphite pebble reflector. A novel neutronics and depletion methodology---the multiple burnup state methodology was developed for an accurate and efficient search for the equilibrium composition of an arbitrary continuously refueled pebble bed reactor core. The Burnup Equilibrium Analysis Utility (BEAU) computer program was developed to implement this methodology. BEAU was successfully benchmarked against published results generated with existing equilibrium depletion codes VSOP and PEBBED for a high temperature gas cooled pebble bed reactor. Three parametric studies were performed for exploring the design space of the PB-FHR---to select a fuel design for the PB-FHR] to select a core configuration; and to optimize the PB-FHR design. These parametric studies investigated trends in the dependence of important reactor performance parameters such as burnup, temperature reactivity feedback, radiation damage, etc on the reactor design variables and attempted to understand the underlying reactor physics responsible for these trends. A pebble fuel parametric study determined that pebble fuel should be designed with a carbon to heavy metal ratio (C/HM) less than 400 to maintain negative coolant temperature reactivity coefficients. Seed and thorium blanket-, seed and inert pebble reflector- and seed only core configurations were investigated for annular FHR PBRs---the C/HM of the blanket pebbles and discharge burnup of the thorium blanket pebbles were additional design variable for core configurations with thorium blankets. Either a thorium blanket or graphite pebble reflector is required to shield the outer graphite reflector enough to extend its service lifetime to 60 EFPY. The fuel fabrication costs and long cycle lengths of the thorium blanket fuel limit the potential economic advantages of using a thorium blanket. Therefore, the seed and pebble reflector core configuration was adopted as the baseline core configuration. Multi-objective optimization with respect to economics was performed for the PB-FHR accounting for safety and other physical design constraints derived from the high-level safety regulatory criteria. These physical constraints were applied along in a design tool, Nuclear Application Value Estimator, that evaluated a simplified cash flow economics model based on estimates of reactor performance parameters calculated using correlations based on the results of parametric design studies for a specific PB-FHR design and a set of economic assumptions about the electricity market to evaluate the economic implications of design decisions. The optimal PB-FHR design---Mark 1 PB-FHR---is described along with a detailed summary of its performance characteristics including: the burnup, the burnup evolution, temperature reactivity coefficients, the power distribution, radiation damage distributions, control element worths, decay heat curves and tritium production rates. The Mk1 PB-FHR satisfies the PB-FHR safety criteria. The fuel, moderator (pebble core, pebble shell, graphite matrix, TRISO layers) and coolant have global negative temperature reactivity coefficients and the fuel temperatures are well within their limits.

Paleoenvironmental reconstruction of lagoonal strata from Sri Lanka using multiple physical properties proxies to assure stratigraphic continuity

NASA Astrophysics Data System (ADS)

Ranasinghage, P. N.; Ortiz, J. D.; Moore, A.; Siriwardana, C.

2009-12-01

Core collapsing is a common problem in studies of lagoonal sediment cores. Coring liquefied sediments below the water table can lead to collapse of material from upper core drives in to the hole. This can be prevented by casing the hole. But casing is not always possible due to practical issues such as coring device type, resources, or time constraints. In such cases identifying the collapsed material in each drive is necessary to ensure accurate results. Direct visual identification of collapsed portion is not always possible and may not be precise. This study successfully recognized collapsed material using a suite of physical properties measurements including: visible (VIS) reflectance spectroscopy, magnetic susceptibility and grain size spectra. This enables us to use the verified stratigraphically continuous records for paleo-environmental studies. Sediment cores were collected from three coastal lagoons and a swale along south eastern and eastern Sri Lanka. Cores were collected using a customized AMS soil coring device with a 1-m long sample barrel. The metal barrel of this instrument collects a 2.5 cm diameter sample in 1-m long plastic tubes. Coring was conducted to refusal, with a maximum depth of 5 m. Casing was not applied to the holes due to small core diameter and time constrains. Drill holes were placed at locations situated both below and above the water level of the lagoons. A total of 100 m of sediment core were obtained from these locations. After opening the cores, suspected collapsed material was initially identified by visual observation using a high power binocular microscope. Particle size, magnetic susceptibility, X-ray fluorescence (XRF) and Diffuse Spectral Reflectance (DSR) was then measured on all cores at 1-2 cm resolution to precisely define the repeated sediment intervals. Down core variation plots of magnetic susceptibility, CIE L* (lightness), a*(red/green difference), b* (blue and yellow difference) clearly record abrupt changes at core drive boundaries at the presence of collapsed material. The correlation of grain-size spectra from the bottom and top of consecutive drives was used to precisely determine the thickness of the collapsed material between drives. Our analysis of 48 m of core material thus far indicates that ~4.4m or ~9% of the record represents collapsed material which can be excluded from further study. The remaining continuous record was analyzed for paleoenvironmental studies. Down core variation of grain size, geochemical ratios, principle components of DSR and geochemical data, and magnetic susceptibility from all locations indicate a gradual filling of these deep lagoons and a transition from reducing to oxic conditions. According to an age model constructed for a nearby lagoon the onset of regression began ~6,000 years BP. Several instantaneous sedimentation events were recorded in all lagoons. Further studies will be carried out to determine whether these represent tsunami, storm surge, or flood deposits.

Cryo-EM Structure of the TOM Core Complex from Neurospora crassa.

PubMed

Bausewein, Thomas; Mills, Deryck J; Langer, Julian D; Nitschke, Beate; Nussberger, Stephan; Kühlbrandt, Werner

2017-08-10

The TOM complex is the main entry gate for protein precursors from the cytosol into mitochondria. We have determined the structure of the TOM core complex by cryoelectron microscopy (cryo-EM). The complex is a 148 kDa symmetrical dimer of ten membrane protein subunits that create a shallow funnel on the cytoplasmic membrane surface. In the core of the dimer, the β-barrels of the Tom40 pore form two identical preprotein conduits. Each Tom40 pore is surrounded by the transmembrane segments of the α-helical subunits Tom5, Tom6, and Tom7. Tom22, the central preprotein receptor, connects the two Tom40 pores at the dimer interface. Our structure offers detailed insights into the molecular architecture of the mitochondrial preprotein import machinery. Copyright © 2017 Elsevier Inc. All rights reserved.

Method of Fault Detection and Rerouting

NASA Technical Reports Server (NTRS)

Gibson, Tracy L. (Inventor); Medelius, Pedro J. (Inventor); Lewis, Mark E. (Inventor)

2013-01-01

A system and method for detecting damage in an electrical wire, including delivering at least one test electrical signal to an outer electrically conductive material in a continuous or non-continuous layer covering an electrically insulative material layer that covers an electrically conductive wire core. Detecting the test electrical signals in the outer conductive material layer to obtain data that is processed to identify damage in the outer electrically conductive material layer.

Protein secretion through autotransporter and two-partner pathways.

PubMed

Jacob-Dubuisson, Françoise; Fernandez, Rachel; Coutte, Loic

2004-11-11

Two distinct protein secretion pathways, the autotransporter (AT) and the two-partner secretion (TPS) pathways are characterized by their apparent simplicity. Both are devoted to the translocation across the outer membrane of mostly large proteins or protein domains. As implied by their name, AT proteins contain their own transporter domain, covalently attached to the C-terminal extremity of the secreted passenger domain, while TPS systems are composed of two separate proteins, with TpsA being the secreted protein and TpsB its specific transporter. In both pathways, the secreted proteins are exported in a Sec-dependent manner across the inner membrane, after which they cross the outer membrane with the help of their cognate transporters. The AT translocator domains and the TpsB proteins constitute distinct families of protein-translocating, outer membrane porins of Gram-negative bacteria. Both types of transporters insert into the outer membrane as beta-barrel proteins possibly forming oligomeric pores in the case of AT and serve as conduits for their cognate secreted proteins or domains across the outer membrane. Translocation appears to be folding-sensitive in both pathways, indicating that AT passenger domains and TpsA proteins cross the periplasm and the outer membrane in non-native conformations and fold progressively at the cell surface. A major difference between AT and TPS pathways arises from the manner by which specificity is established between the secreted protein and its transporter. In AT, the covalent link between the passenger and the translocator domains ensures the translocation of the former without the need for a specific molecular recognition between the two modules. In contrast, the TPS pathway has solved the question of specific recognition between the TpsA proteins and their transporters by the addition to the TpsA proteins of an N-proximal module, the conserved TPS domain, which represents a hallmark of the TPS pathway.

The host outer membrane proteins OmpA and OmpC are associated with the Shigella phage Sf6 virion

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

Zhao Haiyan, E-mail: zhaohy@ku.ed; Sequeira, Reuben D., E-mail: sequen@ku.ed; Galeva, Nadezhda A., E-mail: galeva@ku.ed

2011-01-20

Assembly of dsDNA bacteriophage is a precisely programmed process. Potential roles of host cell components in phage assembly haven't been well understood. It was previously reported that two unidentified proteins were present in bacteriophage Sf6 virion (Casjens et al, 2004, J.Mol.Biol. 339, 379-394, Fig. 2A). Using tandem mass spectrometry, we have identified the two proteins as outer membrane proteins (OMPs) OmpA and OmpC from its host Shigella flexneri. The transmission electron cryo-microscopy structure of Sf6 shows significant density at specific sites at the phage capsid inner surface. This density fit well with the characteristic beta-barrel domains of OMPs, thus maymore » be due to the two host proteins. Locations of this density suggest a role in Sf6 morphogenesis reminiscent of phage-encoded cementing proteins. These data indicate a new, OMP-related phage:host linkage, adding to previous knowledge that some lambdoid bacteriophage genomes contain OmpC-like genes that express phage-encoded porins in the lysogenic state.« less

Comparison of secondary flows and boundary-layer accumulations in several turbine nozzles

NASA Technical Reports Server (NTRS)

Kofskey, Milton G; Allen, Hubert W; Herzig, Howard Z

1953-01-01

An investigation was made of losses and secondary flows in three different turbine nozzle configurations in annular cascade. Appreciable outer shroud loss cores (passage vortices) were found to exist at the discharge of blades which had thickened suction surface boundary layers near the outer shroud. Blade designs having thinner boundary layers did not show such outer shroud loss cores, but indicated greater inward radial flow of low momentum air, in the wake loss is to this extent an indication of the presence or absence of radial flow. The blade wake was a combination of profile loss and low momentum air from the outer shroud, and the magnitude of the wake loss is to this extent an indication of the presence or absence of radial flow. At a high Mach number, shock-boundary-layer thickening on the blade suction surfaces provided an additional radial flow path for low momentum air, which resulted in large inner shroud loss regions accompanied by large deviations from design values of discharge angle. (author)

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

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

Shapiro, B I; Tyshkunova, E S; Kondorskiy, A D

2015-12-31

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 themore » 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. (nanophotonics)« less

15 CFR 240.6 - Tolerances.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE STANDARDS FOR BARRELS BARRELS AND OTHER CONTAINERS FOR LIME § 240.6 Tolerances. (a) When lime is packed in barrels the tolerance to be allowed on the large barrel or the small barrel of lime shall be 5 pounds in excess or in deficiency on any individual barrel...

A targeted boost-and-sort immunization strategy using Escherichia coli BamA identifies rare growth inhibitory antibodies.

PubMed

Vij, Rajesh; Lin, Zhonghua; Chiang, Nancy; Vernes, Jean-Michel; Storek, Kelly M; Park, Summer; Chan, Joyce; Meng, Y Gloria; Comps-Agrar, Laetitia; Luan, Peng; Lee, Sophia; Schneider, Kellen; Bevers, Jack; Zilberleyb, Inna; Tam, Christine; Koth, Christopher M; Xu, Min; Gill, Avinash; Auerbach, Marcy R; Smith, Peter A; Rutherford, Steven T; Nakamura, Gerald; Seshasayee, Dhaya; Payandeh, Jian; Koerber, James T

2018-05-08

Outer membrane proteins (OMPs) in Gram-negative bacteria are essential for a number of cellular functions including nutrient transport and drug efflux. Escherichia coli BamA is an essential component of the OMP β-barrel assembly machinery and a potential novel antibacterial target that has been proposed to undergo large (~15 Å) conformational changes. Here, we explored methods to isolate anti-BamA monoclonal antibodies (mAbs) that might alter the function of this OMP and ultimately lead to bacterial growth inhibition. We first optimized traditional immunization approaches but failed to identify mAbs that altered cell growth after screening >3000 hybridomas. We then developed a "targeted boost-and-sort" strategy that combines bacterial cell immunizations, purified BamA protein boosts, and single hybridoma cell sorting using amphipol-reconstituted BamA antigen. This unique workflow improves the discovery efficiency of FACS + mAbs by >600-fold and enabled the identification of rare anti-BamA mAbs with bacterial growth inhibitory activity in the presence of a truncated lipopolysaccharide layer. These mAbs represent novel tools for dissecting the BamA-mediated mechanism of β-barrel folding and our workflow establishes a new template for the efficient discovery of novel mAbs against other highly dynamic membrane proteins.

The Pre-Messinian Total Petroleum System of the Provence Basin, Western Mediterranean Sea

USGS Publications Warehouse

Pawlewicz, Mark

2004-01-01

The Provence Basin is in that portion of the western Mediterranean Sea that is deeper than 2 kilometers. The basin lies essentially beyond the outer continental shelf, between the countries of France, Italy, and Algeria, the Balearic Islands, and the islands of Sardinia and Corsica. It encompasses nearly 300,000 square kilometers and includes the Rhone River submarine fan on the continental slope of southern France. It is province 4068 in the World Energy study. A single, hypothetical, total petroleum system (TPS), the Pre-Messinian TPS (406801), was described for the Provence Basin. The designation hypothetical is used because there is no hydrocarbon production from the basin. The Provence Basin is a deep-water Tertiary rift basin in which the geothermal gradients vary regionally. The Red Sea Basin shares a similar geologic and thermal history with the rifted western Mediterranean Sea and was used as an analog to better understand the genesis of the Provence Basin and as a guide to estimating possible undiscovered amounts of hydrocarbons. For this assessment the basin was given a potential, at the mean, for undiscovered resources of 51 trillion cubic feet (1.4 trillion cubic meters) gas, 0.42 billion barrels oil, and 2.23 million barrels natural gas liquids.

The chemical composition of the cores of the terrestrial planets and the moon

NASA Technical Reports Server (NTRS)

Kuskov, O. L.; Khitarov, N. I.

1977-01-01

Using models of the quasi-chemical theory of solutions, the activity coefficients of silicon are calculated in the melts Fe-Si, Ni-Si, and Fe-Ni-Si. The calculated free energies of solution of liquid nickel and silicon in liquid iron in the interval 0 to 1400 kbar and 1500 to 4000 K, shows that Fe-Ni-Si alloy is stable under the conditions of the outer core of the earth and the cores of the terrestrial planets. The oxidation-reduction conditions are studied, and the fugacity of oxygen in the mantles of the planets and at the core-mantle boundary are calculated. The mechanism of reduction of silicon is analyzed over a broad interval of p and T. The interaction between the matter of the core and mantle is studied, resulting in the extraction of silicon from the mantle and its solution in the material of the core. It is concluded that silicon can enter into the composition of the outer core of the earth and Venus, but probably does not enter into the composition of the cores of Mercury, Mars, and the moon, if in fact the latter possesses one.

A conformational landscape for alginate secretion across the outer membrane of Pseudomonas aeruginosa

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

Tan, Jingquan; Rouse, Sarah L.; Li, Dianfan

2014-08-01

Crystal structures of the β-barrel porin AlgE reveal a mechanism whereby alginate is exported from P. aeruginosa for biofilm formation. The exopolysaccharide alginate is an important component of biofilms produced by Pseudomonas aeruginosa, a major pathogen that contributes to the demise of cystic fibrosis patients. Alginate exits the cell via the outer membrane porin AlgE. X-ray structures of several AlgE crystal forms are reported here. Whilst all share a common β-barrel constitution, they differ in the degree to which loops L2 and T8 are ordered. L2 and T8 have been identified as an extracellular gate (E-gate) and a periplasmic gatemore » (P-gate), respectively, that reside on either side of an alginate-selectivity pore located midway through AlgE. Passage of alginate across the membrane is proposed to be regulated by the sequential opening and closing of the two gates. In one crystal form, the selectivity pore contains a bound citrate. Because citrate mimics the uronate monomers of alginate, its location is taken to highlight a route through AlgE taken by alginate as it crosses the pore. Docking and molecular-dynamics simulations support and extend the proposed transport mechanism. Specifically, the P-gate and E-gate are flexible and move between open and closed states. Citrate can leave the selectivity pore bidirectionally. Alginate docks stably in a linear conformation through the open pore. To translate across the pore, a force is required that presumably is provided by the alginate-synthesis machinery. Accessing the open pore is facilitated by complex formation between AlgE and the periplasmic protein AlgK. Alginate can thread through a continuous pore in the complex, suggesting that AlgK pre-orients newly synthesized exopolysaccharide for delivery to AlgE.« less

Geological and paleontological results from the WISSARD (Whillans Ice Stream Subglacial Access Research Drilling) Project

NASA Astrophysics Data System (ADS)

Scherer, R. P.; Powell, R. D.; Coenen, J. J.; Hodson, T. O.; Puttkammer, R.; Tulaczyk, S. M.

2015-12-01

The WISSARD project recovered sediment cores and other geological materials from beneath the Whillans Ice Stream in West Antarctica during two drilling seasons; Subglacial Lake Whillans (SLW) in 2013 and 100km downstream at the ice stream grounding-zone (WGZ) in 2015. SLW is characterized by 2 m of freshwater with a high suspended-sediment load, whereas WGZ has a 10 m column of clear, fully marine water with an active community of marine organisms. Three coring devices were deployed as part of WISSARD, including (1) a multicorer, which recovers 3 unaltered sediment-water interface cores, up to 0.5m, (2) a piston corer, also deployed as a gravity corer, with a 3m core barrel, and (3) a percussion coring system with a 5m core barrel. Sediments recovered from SLW are muddy diamicton with minimal stratification. The sediments are characteristic of active till, not water-column deposition. The till is weak and effective stresses very low, thus till flux from deformation must also be low. Water through flow is sufficient to carry suspended clays and silts, but not transfer large volumes of sediment in the current glaciological regime. Microfossils and geochemical tracers (e.g., biomarkers, 10Be and 14C) in SLW sediments indicate Pleistocene input from open water conditions, plus input and mixing of components derived from older Cenozoic strata. Diatoms and other sedimentary characteristics of SLW are entirely consistent with material previously recovered from upstream sites on the Whillans Ice Stream (UpB), but show evidence of further cumulative subglacial shear strain, suggesting downstream translation as deforming till. Sedimentary components from WGZ indicate significant input from sources other than from the Whillans Ice Stream. Sediment cores include distinct stratigraphic variability, with differing geochemical and sedimentary components indicative of input from changing source beds. Components indicate a mixture of Quaternary and older components. The lower ca. 10m of ice at WGZ contained abundant sedimentary debris, and active melting and rainout of basal debris was observed. We attribute much of the stratigraphy of the upper sedimentary layers at WGZ, which include soft mud and rock clasts, to ongoing basal melting. This may represent recent grounding line retreat.

Electrically operated magnetic switch designed to display reduced leakage inductance

DOEpatents

Cook, Edward G.

1994-01-01

An electrically operated magnetic switch is disclosed herein for use in opening and closing a circuit between two terminals depending upon the voltage across these terminals. The switch so disclosed is comprised of a ferrite core in the shape of a toroid having opposing ends and opposite inner and outer sides and an arrangement of electrically conductive components defining at least one current flow path which makes a number of turns around the core. This arrangement of components includes a first plurality of electrically conducive rigid rods parallel with and located outside the outer side of the core and a second plurality of electrically conductive rigid rods parallel with and located inside the inner side of the core. The arrangement also includes means for electrically connecting these rods together so that the define the current flow path. In one embodiment, this latter means uses rigid cross-tab means. In another, preferred embodiment, printed circuits on rigid dielectric substrates located on opposite ends of the core are utilized to interconnect the rods together.

Preparation of Geophysical Fluid Flow Experiments With The Rotating Spherical Gap Flow Model In Space

NASA Astrophysics Data System (ADS)

Egbers, C.

The'GeoFlow' is an ESA experiment planned for the Fluid Science Laboratory on ISS under the scientific coordination (PI) of the Department of Aerodynamics and Fluid Mechanics (LAS) at the Brandenburg Technical University (BTU) of Cottbus, Germany. The objective of the experiment is to study thermal convection in the gap between two concentric rotating (full) spheres. A central symmetric force field simi- lar to the gravity field acting on planets can be produced by applying a high voltage between inner and outer sphere using the dielectrophoretic effect (rotating capacitor). To counter the unidirectional gravity under terrestrial conditions, this experiment re- quires a microgravity environment. The parameters of the experiment are chosen in analogy to the thermal convective motions in the outer core of the Earth. In analogy to geophysical motions in the Earth`s liquid core the experiment can rotate as solid body as well as differential (inner to outer). Thermal convection is produced by heat- ing the inner sphere and cooling the outer ones. Furtheron, the variation of radius ratio between inner and outer sphere is foreseen as a parameter variation. The flows to be investigated will strongly depend on the gap width and on the Prandtl number.

Geochemistry and magnetic sediment distribution at the western boundary upwelling system of southwest Atlantic

NASA Astrophysics Data System (ADS)

Cruz, Anna P. S.; Barbosa, Catia F.; Ayres-Neto, Arthur; Munayco, Pablo; Scorzelli, Rosa B.; Amorim, Nívea Santos; Albuquerque, Ana L. S.; Seoane, José C. S.

2018-02-01

In order to investigate the chemical and magnetic characteristics of sediments of the western boundary upwelling system of Southwest Atlantic we analyzed magnetic susceptibility, grain size distribution, total organic carbon, heavy mineral abundance, Fe associated with Mössbauer spectra, and Fe and Mn of pore water to evaluate the deposition patterns of sediments. Four box-cores were collected along a cross-shelf transect. Brazil Current and coastal plume exert a primary control at the inner and outer shelf cores, which exhibited similar depositional patterns characterized by a high abundance of heavy minerals (mean 0.21% and 0.08%, respectively) and very fine sand, whereas middle shelf cores presented low abundances of heavy minerals (mean 0.03%) and medium silt. The inner shelf was dominated by sub-angular grains, while in middle and outer shelf cores well-rounded grains were found. The increasing Fe3+:Fe2+ ratio from the inner to the outer shelf reflects farther distance to the sediment source. The outer shelf presented well-rounded minerals, indicating abrasive processes as a result of transport by the Brazil Current from the source areas. In the middle shelf, cold-water intrusion of the South Atlantic Central Water contributes to the primary productivity, resulting in higher deposition of fine sediment and organic carbon accumulation. The high input of organic carbon and the decreased grain size are indicative of changes in the hydrodynamics and primary productivity fueled by the western boundary upwelling system, which promotes loss of magnetization due to the induction of diagenesis of iron oxide minerals.

Crystal structure of an antigenic outer-membrane protein from Salmonella Typhi suggests a potential antigenic loop and an efflux mechanism.

PubMed

Guan, Hong-Hsiang; Yoshimura, Masato; Chuankhayan, Phimonphan; Lin, Chien-Chih; Chen, Nai-Chi; Yang, Ming-Chi; Ismail, Asma; Fun, Hoong-Kun; Chen, Chun-Jung

2015-11-13

ST50, an outer-membrane component of the multi-drug efflux system from Salmonella enterica serovar Typhi, is an obligatory diagnostic antigen for typhoid fever. ST50 is an excellent and unique diagnostic antigen with 95% specificity and 90% sensitivity and is used in the commercial diagnosis test kit (TYPHIDOT(TM)). The crystal structure of ST50 at a resolution of 2.98 Å reveals a trimer that forms an α-helical tunnel and a β-barrel transmembrane channel traversing the periplasmic space and outer membrane. Structural investigations suggest significant conformational variations in the extracellular loop regions, especially extracellular loop 2. This is the location of the most plausible antibody-binding domain that could be used to target the design of new antigenic epitopes for the development of better diagnostics or drugs for the treatment of typhoid fever. A molecule of the detergent n-octyl-β-D-glucoside is observed in the D-cage, which comprises three sets of Asp361 and Asp371 residues at the periplasmic entrance. These structural insights suggest a possible substrate transport mechanism in which the substrate first binds at the periplasmic entrance of ST50 and subsequently, via iris-like structural movements to open the periplasmic end, penetrates the periplasmic domain for efflux pumping of molecules, including poisonous metabolites or xenobiotics, for excretion outside the pathogen.

Accumulation of phosphatidic acid increases vancomycin resistance in Escherichia coli.

PubMed

Sutterlin, Holly A; Zhang, Sisi; Silhavy, Thomas J

2014-09-01

In Gram-negative bacteria, lipopolysaccharide (LPS) contributes to the robust permeability barrier of the outer membrane, preventing entry of toxic molecules such as antibiotics. Mutations in lptD, the beta-barrel component of the LPS transport and assembly machinery, compromise LPS assembly and result in increased antibiotic sensitivity. Here, we report rare vancomycin-resistant suppressors that improve barrier function of a subset of lptD mutations. We find that all seven suppressors analyzed mapped to the essential gene cdsA, which is responsible for the conversion of phosphatidic acid to CDP-diacylglycerol in phospholipid biosynthesis. These cdsA mutations cause a partial loss of function and, as expected, accumulate phosphatidic acid. We show that this suppression is not confined to mutations that cause defects in outer membrane biogenesis but rather that these cdsA mutations confer a general increase in vancomycin resistance, even in a wild-type cell. We use genetics and quadrupole time of flight (Q-TOF) liquid chromatography-mass spectrometry (LC-MS) to show that accumulation of phosphatidic acid by means other than cdsA mutations also increases resistance to vancomycin. We suggest that increased levels of phosphatidic acid change the physical properties of the outer membrane to impede entry of vancomycin into the periplasm, hindering access to its target, an intermediate required for the synthesis of the peptidoglycan cell wall. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Small arms mini-fire control system: fiber-optic barrel deflection sensor

NASA Astrophysics Data System (ADS)

Rajic, S.; Datskos, P.; Lawrence, W.; Marlar, T.; Quinton, B.

2012-06-01

Traditionally the methods to increase firearms accuracy, particularly at distance, have concentrated on barrel isolation (free floating) and substantial barrel wall thickening to gain rigidity. This barrel stiffening technique did not completely eliminate barrel movement but the problem was significantly reduced to allow a noticeable accuracy enhancement. This process, although highly successful, came at a very high weight penalty. Obviously the goal would be to lighten the barrel (firearm), yet achieve even greater accuracy. Thus, if lightweight barrels could ultimately be compensated for both their static and dynamic mechanical perturbations, the result would be very accurate, yet significantly lighter weight, weapons. We discuss our development of a barrel reference sensor system that is designed to accomplish this ambitious goal. Our optical fiber-based sensor monitors the barrel muzzle position and autonomously compensates for any induced perturbations. The reticle is electronically adjusted in position to compensate for the induced barrel deviation in real time.

Torsional Oscillations of the Earths's Core

NASA Technical Reports Server (NTRS)

Hide, Raymond; Boggs, Dale H.; Dickey, Jean O.

1997-01-01

Torsional oscillations of the Earth's liquid metallic outer core are investigated by diving the core into twenty imaginary e1qui-volume annuli coaxial with the axis of ratation of the Earth and determining temproal fluctuations in the axial component of angular memonetum of each annulus under the assumption of iso-rotation on cylindrical surfaces.

Three-dimensional structure of basal body triplet revealed by electron cryo-tomography

PubMed Central

Li, Sam; Fernandez, Jose-Jesus; Marshall, Wallace F; Agard, David A

2012-01-01

Basal bodies and centrioles play central roles in microtubule (MT)-organizing centres within many eukaryotes. They share a barrel-shaped cylindrical structure composed of nine MT triplet blades. Here, we report the structure of the basal body triplet at 33 Å resolution obtained by electron cryo-tomography and 3D subtomogram averaging. By fitting the atomic structure of tubulin into the EM density, we built a pseudo-atomic model of the tubulin protofilaments at the core of the triplet. The 3D density map reveals additional densities that represent non-tubulin proteins attached to the triplet, including a large inner circular structure in the basal body lumen, which functions as a scaffold to stabilize the entire basal body barrel. We found clear longitudinal structural variations along the basal body, suggesting a sequential and coordinated assembly mechanism. We propose a model in which δ-tubulin and other components participate in the assembly of the basal body. PMID:22157822

The Effects of Earth's Outer Core's Viscosity on Geodynamo Models

NASA Astrophysics Data System (ADS)

Dong, C.; Jiao, L.; Zhang, H.

2017-12-01

Geodynamo process is controlled by mathematic equations and input parameters. To study effects of parameters on geodynamo system, MoSST model has been used to simulate geodynamo outputs under different outer core's viscosity ν. With spanning ν for nearly three orders when other parameters fixed, we studied the variation of each physical field and its typical length scale. We find that variation of ν affects the velocity field intensely. The magnetic field almost decreases monotonically with increasing of ν, while the variation is no larger than 30%. The temperature perturbation increases monotonically with ν, but by a very small magnitude (6%). The averaged velocity field (u) of the liquid core increases with ν as a simple fitted scaling relation: u∝ν0.49. The phenomenon that u increases with ν is essentially that increasing of ν breaks the Taylor-Proudman constraint and drops the critical Rayleigh number, and thus u increases under the same thermal driving force. Forces balance is analyzed and balance mode shifts with variation of ν. When compared with former studies of scaling laws, this study supports the conclusion that in a certain parameter range, the magnetic field strength doesn't vary much with the viscosity, but opposes to the assumption that the velocity field has nothing to do with the outer core viscosity.

Complementary high performance sensing of gases and liquids using silver nanotube

NASA Astrophysics Data System (ADS)

Isro, Suhandoko D.; Iskandar, Alexander A.; Tjia, May-On

2017-11-01

A study on refractive index sensing using a silver nanotube is carried out to investigate the relative advantages of sensing gaseous and liquid samples outside the tube (outer sensing) and inside the core (inner sensing). The geometrical and material parameters of the nanotube are varied to explore the favorable sensing performances covering the range of refractive indices between 1.1 and 1.5. It is shown that the performances at the three sensing points considered are consistently improved with decreased shell thickness and core radius in both sensing modes. While the performance is also monotonously and drastically enhanced with decreased counter permittivity in inner sensing, the similarly large variations in the outer sensing mode are less than strictly consistent. The study further shows that the most favorable FOM values are attained by both sensing modes with 2.5 nm Ag shell thickness and 27.5 nm core radius of the nanotube, whereas the most favorable counter permittivities are different for the two modes. Remarkably, the trend of increasing FOM for samples of lower refractive indices in outer sensing is entirely reversed in inner sensing with roughly the same level of performances. Thus, the core/shell structure of the silver nanotube offers the complementary high performance sensing of gases and liquids using the two sensing modes with appropriately chosen system parameters.

Radioisotopic heat source

DOEpatents

Sayell, E.H.

1973-10-23

A radioisotopic heat source is described which includes a core of heat productive, radioisotopic material, an impact resistant layer of graphite surrounding said core, and a shell of iridium metal intermediate the core and the impact layer. The source may also include a compliant mat of iridium between the core and the iridium shell, as well as an outer covering of iridium metal about the entire heat source. (Official Gazette)

Structural response of 1/20-scale models of the Clinch River Breeder Reactor to a simulated hypothetical core-disruptive accident

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

Romander, C M; Cagliostro, D J

Five experiments were performed to help evaluate the structural integrity of the reactor vessel and head design and to verify code predictions. In the first experiment (SM 1), a detailed model of the head was loaded statically to determine its stiffness. In the remaining four experiments (SM 2 to SM 5), models of the vessel and head were loaded dynamically under a simulated 661 MW-s hypothetical core disruptive accident (HCDA). Models SM 2 to SM 4, each of increasing complexity, systematically showed the effects of upper internals structures, a thermal liner, core support platform, and torospherical bottom on vessel response.more » Model SM 5, identical to SM 4 but more heavily instrumented, demonstrated experimental reproducibility and provided more comprehensive data. The models consisted of a Ni 200 vessel and core barrel, a head with shielding and simulated component masses, and an upper internals structure (UIS).« less

Probing the Structure near the Top of the Earth's Outer Core Using SmKS Traveltimes

NASA Astrophysics Data System (ADS)

Tang, V. C.; Zhao, L.; Hung, S.

2013-12-01

The Earth's solid inner core is composed of heavy Fe and Ni with a fraction of light elements such as O, S, Si. These light elements were expelled from the inner core during its formation and rise up through the outer core as the result of buoyancy, but their existence is still a mystery. Some authors have presented seismological evidence for lowered wave speed beneath the core-mantle boundary (CMB) relative to PREM, suggesting light elements there, but counter argument also exists. In this study, we use traveltime measurements from recorded and modeled SmKS waves to investigate the effect of the velocity under the CMB on the differential traveltimes between SKKS and S3KS waves (TS3KS-TSKKS). Due to the long propagation distance and interference with neighboring phases, the arrival times of SKKS and S3KS waves are difficult to define accurately in the records. Therefore in our analysis we measure both the observed and model-predicted differential traveltime TS3KS-TSKKS by cross-correlating the waveform of Hilbert-transformed S3KS with that of SKKS. We use synthetic seismograms calculated by the Direct-Solution Method (DSM) in a suite of 1D models with different structural profiles under the CMB to examine the existence of a zone of lowered velocity at the top of the outer core. We are conducting a systematic investigation using waveforms available at IRIS from globally distributed large deep earthquakes. Results from events we have processed so far indicate that the velocity under the CMB is slightly slower than that in PREM.

Electrophoretic manipulation of multiple-emulsion droplets

NASA Astrophysics Data System (ADS)

Schoeler, Andreas M.; Josephides, Dimitris N.; Chaurasia, Ankur S.; Sajjadi, Shahriar; Mesquida, Patrick

2014-02-01

Electrophoretic manipulation of multiple-emulsion oil-in-water-in-oil (O/W)/O and water-in-oil-in-water-in-oil (W/O/W)/O core-shell droplets is shown. It was found that the electrophoretic mobility of the droplets is determined solely by the outer water shell, regardless of size or composition of the inner droplets. It was observed that the surface charge of the outer water shell can be changed and the polarity can be reversed through contact with a biased electrode in a similar way as with simple W/O droplets. Furthermore, addition of the anionic surfactant, sodium dodecyl sulfate to the outer water shell reverses the initial polarity and hence, electrophoretic mobility of the core-shell droplets before contact with an electrode. The results have practical implications for the manipulation of oil droplets in a continuous oil phase.

Atmospheric Mining in the Outer Solar System: Resource Capturing, Storage, and Utilization

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2014-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as helium 3 and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and hydrogen (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate for hydrogen helium 4 and helium 3, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues.

Multi-modality nanoparticles having optically responsive shape

DOEpatents

Chen, Fanqing; Bouchard, Louis-Serge

2015-05-19

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

Structure of the human voltage-dependent anion channel

PubMed Central

Bayrhuber, Monika; Meins, Thomas; Habeck, Michael; Becker, Stefan; Giller, Karin; Villinger, Saskia; Vonrhein, Clemens; Griesinger, Christian; Zweckstetter, Markus; Zeth, Kornelius

2008-01-01

The voltage-dependent anion channel (VDAC), also known as mitochondrial porin, is the most abundant protein in the mitochondrial outer membrane (MOM). VDAC is the channel known to guide the metabolic flux across the MOM and plays a key role in mitochondrially induced apoptosis. Here, we present the 3D structure of human VDAC1, which was solved conjointly by NMR spectroscopy and x-ray crystallography. Human VDAC1 (hVDAC1) adopts a β-barrel architecture composed of 19 β-strands with an α-helix located horizontally midway within the pore. Bioinformatic analysis indicates that this channel architecture is common to all VDAC proteins and is adopted by the general import pore TOM40 of mammals, which is also located in the MOM. PMID:18832158

The 3D structures of VDAC represent a native conformation

PubMed Central

Hiller, Sebastian; Abramson, Jeff; Mannella, Carmen; Wagner, Gerhard; Zeth, Kornelius

2010-01-01

The most abundant protein of the mitochondrial outer membrane is the voltage-dependent anion channel (VDAC), which facilitates the exchange of ions and molecules between mitochondria and cytosol and is regulated by interactions with other proteins and small molecules. VDAC has been extensively studied for more than three decades, and last year three independent investigations revealed a structure of VDAC-1 exhibiting 19 transmembrane β-strands, constituting a unique structural class of β-barrel membrane proteins. Here, we provide a historical perspective on VDAC research and give an overview of the experimental design used to obtain these structures. Furthermore, we validate the protein refolding approach and summarize biochemical and biophysical evidence that links the 19-stranded structure to the native form of VDAC. PMID:20708406

ONIOM Investigation of the Second-Order Nonlinear Optical Responses of Fluorescent Proteins.

PubMed

de Wergifosse, Marc; Botek, Edith; De Meulenaere, Evelien; Clays, Koen; Champagne, Benoît

2018-05-17

The first hyperpolarizability (β) of six fluorescent proteins (FPs), namely, enhanced green fluorescent protein, enhanced yellow fluorescent protein, SHardonnay, ZsYellow, DsRed, and mCherry, has been calculated to unravel the structure-property relationships on their second-order nonlinear optical properties, owing to their potential for multidimensional biomedical imaging. The ONIOM scheme has been employed and several of its refinements have been addressed to incorporate efficiently the effects of the microenvironment on the nonlinear optical responses of the FP chromophore that is embedded in a protective β-barrel protein cage. In the ONIOM scheme, the system is decomposed into several layers (here two) treated at different levels of approximation (method1/method2), from the most elaborated method (method1) for its core (called the high layer) to the most approximate one (method2) for the outer surrounding (called the low layer). We observe that a small high layer can already account for the variations of β as a function of the nature of the FP, provided the low layer is treated at an ab initio level to describe properly the effects of key H-bonds. Then, for semiquantitative reproduction of the experimental values obtained from hyper-Rayleigh scattering experiments, it is necessary to incorporate electron correlation as described at the second-order Møller-Plesset perturbation theory (MP2) level as well as implicit solvent effects accounted for using the polarizable continuum model (PCM). This led us to define the MP2/6-31+G(d):HF/6-31+G(d)/IEFPCM scheme as an efficient ONIOM approach and the MP2/6-31+G(d):HF/6-31G(d)/IEFPCM as a better compromise between accuracy and computational needs. Using these methods, we demonstrate that many parameters play a role on the β response of FPs, including the length of the π-conjugated segment, the variation of the bond length alternation, and the presence of π-stacking interactions. Then, noticing the small diversity of the FP chromophores, these results highlight the key role of the β-barrel and surrounding residues on β, not only because they can locally break the noncentrosymmetry vital to a β response but also because it can impose geometrical constraints on the chromophore.

Small arms mini-fire control system: fiber-optic barrel deflection sensor

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

Rajic, Slobodan; Datskos, Panos G

Traditionally the methods to increase firearms accuracy, particularly at distance, have concentrated on barrel isolation (free floating) and substantial barrel wall thickening to gain rigidity. This barrel stiffening technique did not completely eliminate barrel movement but the problem was significantly reduced to allow a noticeable accuracy enhancement. This process, although highly successful, came at a very high weight penalty. Obviously the goal would be to lighten the barrel (firearm), yet achieve even greater accuracy. Thus, if lightweight barrels could ultimately be compensated for both their static and dynamic mechanical perturbations, the result would be very accurate, yet significantly lighter weight,more » weapons. We discuss our development of a barrel reference sensor system that is designed to accomplish this ambitious goal. Our optical fiber-based sensor monitors the barrel muzzle position and autonomously compensates for any induced perturbations. The reticle is electronically adjusted in position to compensate for the induced barrel deviation in real time.« less

Permanent-magnet switched-flux machine

DOEpatents

Trzynadlowski, Andrzej M.; Qin, Ling

2011-06-14

A permanent-magnet switched-flux (PMSF) device has an outer rotor mounted to a shaft about a central axis extending axially through the PMSF device. First and second pluralities of permanent-magnets (PMs) are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the outer rotor. An inner stator is coupled to the shaft and has i) a stator core having a core axis co-axial with the central axis; and ii) first and second pluralities of stator poles mounted in first and second circles, radially outwardly from the stator core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.

Permanent-magnet switched-flux machine

DOEpatents

Trzynadlowski, Andrzej M.; Qin, Ling

2012-02-21

A permanent-magnet switched-flux (PMSF) device has an outer rotor mounted to a shaft about a central axis extending axially through the PMSF device. First and second pluralities of permanent-magnets (PMs) are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the outer rotor. An inner stator is coupled to the shaft and has i) a stator core having a core axis co-axial with the central axis; and ii) first and second pluralities of stator poles mounted in first and second circles, radially outwardly from the stator core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.

The rotational shear in pre-collapse cores of massive stars

NASA Astrophysics Data System (ADS)

Zilberman, Noa; Gilkis, Avishai; Soker, Noam

2018-02-01

We evolve stellar models to study the rotational profiles of the pre-explosion cores of single massive stars that are progenitors of core collapse supernovae (CCSNe), and find large rotational shear above the iron core that might play an important role in the jet feedback explosion mechanism by amplifying magnetic fields before and after collapse. Initial masses of 15 and 30 M⊙ and various values of the initial rotation velocity are considered, as well as a reduced mass-loss rate along the evolution and the effect of core-envelope coupling through magnetic fields. We find that the rotation profiles just before core collapse differ between models, but share the following properties. (1) There are narrow zones of very large rotational shear adjacent to convective zones. (2) The rotation rate of the inner core is slower than required to form a Keplerian accretion disc. (3) The outer part of the core and the envelope have non-negligible specific angular momentum compared to the last stable orbit around a black hole (BH). Our results suggest the feasibility of magnetic field amplification which might aid a jet-driven explosion leaving behind a neutron star. Alternatively, if the inner core fails in exploding the star, an accretion disc from the outer parts of the core might form and lead to a jet-driven CCSN which leaves behind a BH.

15 CFR 241.2 - Legal standard barrels.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 15 Commerce and Foreign Trade 1 2013-01-01 2013-01-01 false Legal standard barrels. 241.2 Section..., VEGETABLES AND OTHER DRY COMMODITIES, AND FOR CRANBERRIES § 241.2 Legal standard barrels. (a) Any barrel... form or dimensions, is a legal standard barrel for fruits, vegetables, or other dry commodities other...

15 CFR 241.2 - Legal standard barrels.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 15 Commerce and Foreign Trade 1 2011-01-01 2011-01-01 false Legal standard barrels. 241.2 Section..., VEGETABLES AND OTHER DRY COMMODITIES, AND FOR CRANBERRIES § 241.2 Legal standard barrels. (a) Any barrel... form or dimensions, is a legal standard barrel for fruits, vegetables, or other dry commodities other...

Melting-induced stratification above the Earth's inner core due to convective translation.

PubMed

Alboussière, Thierry; Deguen, Renaud; Melzani, Mickaël

2010-08-05

In addition to its global North-South anisotropy, there are two other enigmatic seismological observations related to the Earth's inner core: asymmetry between its eastern and western hemispheres and the presence of a layer of reduced seismic velocity at the base of the outer core. This 250-km-thick layer has been interpreted as a stably stratified region of reduced composition in light elements. Here we show that this layer can be generated by simultaneous crystallization and melting at the surface of the inner core, and that a translational mode of thermal convection in the inner core can produce enough melting and crystallization on each hemisphere respectively for the dense layer to develop. The dynamical model we propose introduces a clear asymmetry between a melting and a crystallizing hemisphere which forms a basis for also explaining the East-West asymmetry. The present translation rate is found to be typically 100 million years for the inner core to be entirely renewed, which is one to two orders of magnitude faster than the growth rate of the inner core's radius. The resulting strong asymmetry of buoyancy flux caused by light elements is anticipated to have an impact on the dynamics of the outer core and on the geodynamo.

Rapid-quench axially staged combustor

DOEpatents

Feitelberg, Alan S.; Schmidt, Mark Christopher; Goebel, Steven George

1999-01-01

A combustor cooperating with a compressor in driving a gas turbine includes a cylindrical outer combustor casing. A combustion liner, having an upstream rich section, a quench section and a downstream lean section, is disposed within the outer combustor casing defining a combustion chamber having at least a core quench region and an outer quench region. A first plurality of quench holes are disposed within the liner at the quench section having a first diameter to provide cooling jet penetration to the core region of the quench section of the combustion chamber. A second plurality of quench holes are disposed within the liner at the quench section having a second diameter to provide cooling jet penetration to the outer region of the quench section of the combustion chamber. In an alternative embodiment, the combustion chamber quench section further includes at least one middle region and at least a third plurality of quench holes disposed within the liner at the quench section having a third diameter to provide cooling jet penetration to at least one middle region of the quench section of the combustion chamber.

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

NASA Technical Reports Server (NTRS)

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

1998-01-01

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

Atmospheric Mining in the Outer Solar System: Resource Capturing, Storage, and Utilization

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2012-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and hydrogen (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate for hydrogen helium 4 and helium 3, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues.

Ultra high performance connectors for power transmission applications

DOEpatents

Wang, Jy-An; Ren, Fei; Lee, Dominic F; Jiang, Hao

2014-03-04

Disclosed are several examples of an apparatus for connecting the free ends of two electrical power transmission lines having conductor strands disposed around a central, reinforcing core. The examples include an inner sleeve having a body defining an inner bore passing through an axially-extending, central axis, an outer rim surface disposed radially outward from the central bore, and one or more axially-extending grooves penetrating the body at the outer rim surface. Also included is an outer splice having a tubular shaped body with a bore passing coaxially through the central axis, the bore defining an inner rim surface for accepting the inner sleeve. The inner bore of the inner sleeve accepts the reinforcement cores of the two conductors, and the grooves accept the conductor strands in an overlapping configuration so that a majority of the electrical current flows between the overlapped conductor strands when the conductors are transmitting electrical current.

Assessment of undiscovered oil and gas resources of the Assam, Bombay, Cauvery, and Krishna-Godavari Provinces, South Asia, 2011

USGS Publications Warehouse

Klett, T.R.; Schenk, Christopher J.; Wandrey, Craig J.; Charpentier, Ronald R.; Cook, Troy A.; Brownfield, Michael E.; Pitman, Janet K.; Pollastro, Richard M.

2012-01-01

Using a geology-based assessment methodology, the U.S. Geological Survey estimated volumes of undiscovered, technically recoverable, conventional petroleum resources for the Assam, Bombay, Cauvery, and Krishna–Godavari Provinces, South Asia. The estimated mean volumes are as follows: (1) Assam Province, 273 million barrels of crude oil, 1,559 billion cubic feet of natural gas, and 43 million barrels of natural gas liquids; (2) Bombay Province, 1,854 million barrels of crude oil, 15,417 billion cubic feet of natural gas, and 498 million barrels of natural gas liquids; (3) Cauvery Province, 941 million barrels of crude oil, 25,208 billion cubic feet of natural gas, and 654 million barrels of natural gas liquids; and (4) Krishna–Godavari Province, 466 million barrels of crude oil, 37,168 billion cubic feet of natural gas, and 484 million barrels of natural gas liquids. The totals for the four provinces are 3,534 million barrels of crude oil, 79,352 billion cubic feet of natural gas, and 1,679 million barrels of natural gas liquids.

A Large Solid Inner Core at Mercury

NASA Astrophysics Data System (ADS)

Genova, A.; Goossens, S.; Mazarico, E.; Lemoine, F. G.; Neumann, G. A.; Kuang, W.; Sabaka, T. J.; Smith, D. E.; Zuber, M. T.

2018-05-01

New measurements of the polar moments of inertia of the whole planet and of the outer layers (crust+mantle), and simulations of Mercury’s magnetic field dynamo suggest the presence of a solid inner core with a Ric 0.3-0.5 Roc.

Chemical Reaction at the Core-Mantle Boundary from Experimental Study with a Diamond-Anvil Cell (Invited)

NASA Astrophysics Data System (ADS)

Ozawa, H.; Hirose, K.

2010-12-01

Element partitioning between molten iron and mantle minerals was investigated to 146 GPa by a combination of laser-heated diamond-anvil cell and analytical transmission electron microscope. The chemical compositions of co-existing quenched molten iron and (Mg,Fe)SiO3 perovskite/ferropericlase were determined quantitatively with energy-dispersive X-ray spectrometry and electron energy loss spectroscopy. The results demonstrate that the oxygen solubility in liquid iron co-existing with ferropericlase decreases with pressure to 38 GPa and, whereas the pressure effect is small at higher pressures. It was also revealed that the quenched liquid iron in contact with perovskite contained substantial amounts of oxygen and silicon at the core-mantle boundary (CMB) pressure. The chemical equilibrium between perovskite, ferropericlase, and molten iron at the P-T conditions of the CMB was calculated in Mg-Fe-Si-O system from these experimental results. Note that perovskite is a predominant phase instead of post-perovskite above 3500 K at the CMB pressure. We found that molten iron should include oxygen and silicon more than required to account for the core density deficit of below 10% when co-existing with both perovskite and ferropericlase at the CMB. This suggests that the bulk outer core liquid with <10% density deficit is not in direct contact with the mantle. Dissolutions of light elements from the mantle can produce a gravitationally stratified liquid layer at the topmost outer core, which can be responsible for the low-P wave velocity layer observed there. Such layer physically separates the mantle from the bulk outer core liquid, hindering the chemical reaction between them.

Electrically operated magnetic switch designed to display reduced leakage inductance

DOEpatents

Cook, E.G.

1994-05-10

An electrically operated magnetic switch is disclosed herein for use in opening and closing a circuit between two terminals depending upon the voltage across these terminals. The switch so disclosed is comprised of a ferrite core in the shape of a toroid having opposing ends and opposite inner and outer sides and an arrangement of electrically conductive components defining at least one current flow path which makes a number of turns around the core. This arrangement of components includes a first plurality of electrically conducive rigid rods parallel with and located outside the outer side of the core and a second plurality of electrically conductive rigid rods parallel with and located inside the inner side of the core. The arrangement also includes means for electrically connecting these rods together so that the define the current flow path. In one embodiment, this latter means uses rigid cross-tab means. In another, preferred embodiment, printed circuits on rigid dielectric substrates located on opposite ends of the core are utilized to interconnect the rods together. 10 figures.

Melting relations in the iron-sulfur system at ultra-high pressures - Implications for the thermal state of the earth

NASA Technical Reports Server (NTRS)

Williams, Quentin; Jeanloz, Raymond

1990-01-01

The melting temperatures of FeS-troilite and of a 10-wt-pct sulfur iron alloy have been measured to pressures of 120 and 90 GPa, respectively. The results document that FeS melts at a temperature of 4100 (+ or - 300) K at the pressure of the core-mantle boundary. Eutecticlike behavior persists in the iron-sulfur system to the highest pressures of measurements, in marked contrast to the solid-solutionlike behavior observed at high pressures in the iron-iron oxide system. Iron with 10-wt-pct sulfur melts at a similar temperature as FeS at core-mantle boundary conditions. If the sole alloying elements of iron within the core are sulfur and oxygen and the outer core is entirely liquid, the minimum temperature at the top of the outer core is 4900 (+ or - 400) K. Calculations of mantle geotherms dictate that there must be a temperature increase of between 1000 and 2000 K across thermal boundary layers within the mantle. If D-double-prime is compositionally stratified, it could accommodate the bulk of this temperature jump.

The Density Jump at the Inner Core Boundary in the Eastern and Western Hemispheres

NASA Astrophysics Data System (ADS)

Krasnoshchekov, D. N.; Ovtchinnikov, V. M.

2018-02-01

The results of analysis of more than 1300 new PKiKP/PcP amplitude ratios measured in Southeast Asia and South America at the epicentral distances of 3.2°-35.2° are presented. The density jump in the Eastern Hemisphere of the Earth's inner core (IC) is 0.3 g/cm3, and it is 0.9 g/cm3 in the Western one. Taking the large discrepancy in the obtained estimates into consideration, maintenance of such large lateral variations in the mosaic properties of the IC reflecting surface requires considerable variations in the thermodynamic parameters (mostly temperature) of the inner-outer core transition. However, if the observed asymmetry in the density jump distribution is of a global character, the data presented support the translation model of the IC dynamics. This model implies IC crystallization in the Western Hemisphere and melting in the Eastern one, not vice versa, as suggested by another geodynamic model based on thermochemical convection in the outer core and the thermal balance of the core-mantle system.

Origin of the Earth's Electromagnetic Field Based on the Pulsating Mantle Hypothesis (PMH)

NASA Astrophysics Data System (ADS)

Gholibeigian, Hassan

2017-11-01

In PMH, the Earth's Inner Core's Dislocation (ICD) and Outer Core's Bulge (OCB) phenomena are generated by unbalanced gravitational fields of the Sun and Moon on the Earth. Distance between the Earth's center and inner core's center varies permanently in magnitude and direction inside two hemispheres. Geometrical loci of the inner core's center has the shape of back and force spiral cone in each hemisphere. In other words, the inner core is rotating fast in the outer core inverse of the Earth's rotation a round per day. This mechanism speed up the processes inside the core and generates a Large Scale Forced Convection System (LSFCS) inverse of the Earth's rotation in the core. The LSFCS is the origin of the Earth's electromagnetic field. The LSFCS generates huge mass transfer and momentum of inertia inside the Earth too. The inner core's axis which is the Earth's electromagnetic axis doesn't cross the Earth's geophysical axis and rotates around it per day. The mechanism of this LSFCS has diurnal, monthly and yearly cycles. These cycles are sources of the Earth's electromagnetic field variability. Direction of the variable Earth's magnetic field lines from the South Pole (hemisphere) to the sky and 146 seconds/years apparent solar day length variations can be two observable factors for this mechanism. This dynamic system may occurred inside the other planets like the Sun and the Jupiter.

Geochemical Constraints on Core-Mantle Interaction from Fe/Mn Ratios

NASA Astrophysics Data System (ADS)

Humayun, M.; Qin, L.

2003-12-01

The greater density of liquid iron alloy, and its immiscibility with silicate, maintains the physical separation of the core from the mantle. There are no a priori reasons, however, why the Earth's mantle should be chemically isolated from the core. Osmium isotopic variations in mantle plumes have been interpreted in terms of interaction between outer core and the source regions of deep mantle plumes. If chemical transport occurs across the core-mantle boundary its mechanism remains to be established. The Os isotope evidence has also been interpreted as the signatures of subducted Mn-sediments, which are known to have relatively high Pt/Os. In the mantle, Fe occurs mainly as the divalent ferrous ion, and Mn occurs solely as a divalent ion, and both behave in a geochemically coherent manner because of similarity in ionic charge and radius. Thus, the Fe/Mn ratio is a planetary constant insensitive to processes of mantle differentiation by partial melting. Two processes may perturb the ambient mantle Fe/Mn of 60: a) the subduction of Mn-sediments should decrease the Fe/Mn ratio in plume sources, while b) chemical transport from the outer core may increase the Fe/Mn ratio. The differentiation of the liquid outer core to form the solid inner core may increase abundances of the light element constituents (FeS, FeO, etc.) to the point of exsolution from the core at the CMB. The exact rate of this process is determined by the rate of inner core growth. Two end-member models include 1) inner core formation mainly prior to 3.5 Ga with heat release dominated by radioactive sources, or 2) inner core formation occurring mainly in the last 1.5 Ga with heat release dominated by latent heat. This latter model would imply large fluxes of Fe into the sources of modern mantle plumes. Existing Fe/Mn data for Gorgona and Hawaiian samples place limits on both these processes. We describe a new procedure for the precise determination of the Fe/Mn ratio in magmatic rocks by ICP-MS. This high-resolution study of the Fe/Mn of mantle-derived samples offers a new set of chemical constraints on the rates of inner core differentiation and the viability of Os isotope interpretations.

TGD4 involved in endoplasmic reticulum-to-chloroplast lipid trafficking is a phosphatidic acid binding protein

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

Wang Z.; Xu C.; Benning, C.

The synthesis of galactoglycerolipids, which are prevalent in photosynthetic membranes, involves enzymes at the endoplasmic reticulum (ER) and the chloroplast envelope membranes. Genetic analysis of trigalactosyldiacylglycerol (TGD) proteins in Arabidopsis has demonstrated their role in polar lipid transfer from the ER to the chloroplast. The TGD1, 2, and 3 proteins resemble components of a bacterial-type ATP-binding cassette (ABC) transporter, with TGD1 representing the permease, TGD2 the substrate binding protein, and TGD3 the ATPase. However, the function of the TGD4 protein in this process is less clear and its location in plant cells remains to be firmly determined. The predicted C-terminalmore » {beta}-barrel structure of TGD4 is weakly similar to proteins of the outer cell membrane of Gram-negative bacteria. Here, we show that, like TGD2, the TGD4 protein when fused to DsRED specifically binds phosphatidic acid (PtdOH). As previously shown for tgd1 mutants, tgd4 mutants have elevated PtdOH content, probably in extraplastidic membranes. Using highly purified and specific antibodies to probe different cell fractions, we demonstrated that the TGD4 protein was present in the outer envelope membrane of chloroplasts, where it appeared to be deeply buried within the membrane except for the N-terminus, which was found to be exposed to the cytosol. It is proposed that TGD4 is either directly involved in the transfer of polar lipids, possibly PtdOH, from the ER to the outer chloroplast envelope membrane or in the transfer of PtdOH through the outer envelope membrane.« less

Design and evaluation of hydrophobic coated buoyant core as floating drug delivery system for sustained release of cisapride

PubMed Central

Jacob, Shery; Nair, Anroop B; Patil, Pandurang N

2010-01-01

An inert hydrophobic buoyant coated–core was developed as floating drug delivery system (FDDS) for sustained release of cisapride using direct compression technology. Core contained low density, porous ethyl cellulose, which was coated with an impermeable, insoluble hydrophobic coating polymer such as rosin. It was further seal coated with low viscosity hydroxypropyl methyl cellulose (HPMC E15) to minimize moisture permeation and better adhesion with an outer drug layer. It was found that stable buoyant core was sufficient to float the tablet more than 8 h without the aid of sodium bicarbonate and citric acid. Sustained release of cisapride was achieved with HPMC K4M in the outer drug layer. The floating lag time required for these novel FDDS was found to be zero, however it is likely that the porosity or density of the core is critical for floatability of these tablets. The in vitro release pattern of these tablets in simulated gastric fluid showed the constant and controlled release for prolonged time. It can be concluded that the hydrophobic coated buoyant core could be used as FDDS for gastroretentive delivery system of cisapride or other suitable drugs. PMID:24825997

15 CFR 240.3 - Permissible sizes.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE STANDARDS FOR BARRELS BARRELS AND OTHER CONTAINERS FOR LIME § 240.3 Permissible sizes. Lime in barrels shall be packed only in barrels containing 280 pounds or 180...

Method for manufacturing magnetohydrodynamic electrodes

DOEpatents

Killpatrick, D.H.; Thresh, H.R.

1980-06-24

A method of manufacturing electrodes for use in a magnetohydrodynamic (MHD) generator is described comprising the steps of preparing a billet having a core of a first metal, a tubular sleeve of a second metal, and an outer sheath of an extrusile metal; evacuating the space between the parts of the assembled billet; extruding the billet; and removing the outer jacket. The extruded bar may be made into electrodes by cutting and bending to the shape required for an MHD channel frame. The method forms a bond between the first metal of the core and the second metal of the sleeve strong enough to withstand a hot and corrosive environment.

Scintillator reflective layer coextrusion

DOEpatents

Yun, Jae-Chul; Para, Adam

2001-01-01

A polymeric scintillator has a reflective layer adhered to the exterior surface thereof. The reflective layer comprises a reflective pigment and an adhesive binder. The adhesive binder includes polymeric material from which the scintillator is formed. A method of forming the polymeric scintillator having a reflective layer adhered to the exterior surface thereof is also provided. The method includes the steps of (a) extruding an inner core member from a first amount of polymeric scintillator material, and (b) coextruding an outer reflective layer on the exterior surface of the inner core member. The outer reflective layer comprises a reflective pigment and a second amount of the polymeric scintillator material.

Synthesis of the trisaccharide outer core fragment of Burkholderia cepacia pv. vietnamiensis lipooligosaccharide.

PubMed

Bedini, Emiliano; Cirillo, Luigi; Parrilli, Michelangelo

2012-02-15

The synthesis of β-Gal-(1→3)-α-GalNAc-(1→3)-β-GalNAc allyl trisaccharide as the outer core fragment of Burkholderia cepacia pv. vietnamiensis lipooligosaccharide was accomplished through a concise, optimized, multi-step synthesis, having as key steps three glycosylations, that were in-depth studied performing them under several conditions. The target trisaccharide was designed with an allyl aglycone in order to open a future access to the conjugation with an immunogenic protein en route to the development of a synthetic neoglycoconjugate vaccine against this Burkholderia pathogen. Copyright © 2011 Elsevier Ltd. All rights reserved.

High-Pressure Geophysical Properties of Fcc Phase FeHX

NASA Astrophysics Data System (ADS)

Thompson, E. C.; Davis, A. H.; Bi, W.; Zhao, J.; Alp, E. E.; Zhang, D.; Greenberg, E.; Prakapenka, V. B.; Campbell, A. J.

2018-01-01

Face centered cubic (fcc) FeHX was synthesized at pressures of 18-68 GPa and temperatures exceeding 1,500 K. Thermally quenched samples were evaluated using synchrotron X-ray diffraction (XRD) and nuclear resonant inelastic X-ray scattering (NRIXS) to determine sample composition and sound velocities to 82 GPa. To aid in the interpretation of nonideal (X ≠ 1) stoichiometries, two equations of state for fcc FeHX were developed, combining an empirical equation of state for iron with two distinct synthetic compression curves for interstitial hydrogen. Matching the density deficit of the Earth's core using these equations of state requires 0.8-1.1 wt % hydrogen at the core-mantle boundary and 0.2-0.3 wt % hydrogen at the interface of the inner and outer cores. Furthermore, a comparison of Preliminary Reference Earth Model (PREM) to a Birch's law extrapolation of our experimental results suggests that an iron alloy containing ˜0.8-1.3 wt % hydrogen could reproduce both the density and compressional velocity (VP) of the Earth's outer core.

A diurnal resonance in the ocean tide and in the earth's load response due to the resonant free 'core nutation'

NASA Technical Reports Server (NTRS)

Wahr, J. M.; Sasao, T.

1981-01-01

The effects of the oceans, which are subject to a resonance due to a free rotational eigenmode of an elliptical, rotating earth with a fluid outer core having an eigenfrequency of (1 + 1/460) cycle/day, on the body tide and nutational response of the earth to the diurnal luni-tidal force are computed. The response of an elastic, rotating, elliptical, oceanless earth with a fluid outer core to a given load distribution on its surface is first considered, and the tidal sea level height for equilibrium and nonequilibrium oceans is examined. Computations of the effects of equilibrium and nonequilibrium oceans on the nutational and deformational responses of the earth are then presented which show small but significant perturbations to the retrograde 18.6-year and prograde six-month nutations, and more important effects on the earth body tide, which is also resonant at the free core notation eigenfrequency.

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.

Constructive systems, load-bearing and enclosing structures of high-rise buildings

NASA Astrophysics Data System (ADS)

Anatol'evna Korol', Elena; Olegovna Kustikova, Yuliya

2018-03-01

As the height of the building increases, loads on load-carrying structures increase dramatically, and as a result of the development of high-rise construction, several structural systems of such buildings have been developed: frame, frame-frame, cross-wall, barrel, box-type, box-to-wall ("pipe in pipe", "Trumpet in the farm"), etc. In turn, the barrel systems have their own versions: cantilever support of the ceilings on the trunk, suspension of the outer part of the overlap to the upper carrying console "hanging house" or its support by means of the walls on the lower bearing cantilever, intermediate position of the supporting cantilevers in height to the floor, from a part of floors. The object of the study are the structural solutions of high-rise buildings. The subject of the study is the layout of structural schemes of high-rise buildings, taking into account the main parameters - altitude (height), natural climatic conditions of construction, materials of structural elements and their physical and mechanical characteristics. The purpose of the study is to identify the features and systematization of structural systems of high-rise buildings and the corresponding structural elements. The results of the research make it possible, at the stage of making design decisions, to establish rational parameters for the correspondence between the structural systems of high-rise buildings and their individual elements.

Structure of human Aichi virus and implications for receptor binding.

PubMed

Zhu, Ling; Wang, Xiangxi; Ren, Jingshan; Kotecha, Abhay; Walter, Thomas S; Yuan, Shuai; Yamashita, Teruo; Tuthill, Tobias J; Fry, Elizabeth E; Rao, Zihe; Stuart, David I

2016-09-05

Aichi virus (AiV), an unusual and poorly characterized picornavirus, classified in the genus Kobuvirus, can cause severe gastroenteritis and deaths in children below the age of five years, especially in developing countries 1,2 . The seroprevalence of AiV is approximately 60% in children under the age of ten years and reaches 90% later in life 3,4 . There is no available vaccine or effective antiviral treatment. Here, we describe the structure of AiV at 3.7 Å. This first high-resolution structure for a kobuvirus is intermediate between those of the enteroviruses and cardioviruses, with a shallow, narrow depression bounded by the prominent VP0 CD loops (linking the C and D strands of the β-barrel), replacing the depression known as the canyon, frequently the site of receptor attachment in enteroviruses. VP0 is not cleaved to form VP2 and VP4, so the 'VP2' β-barrel structure is complemented with a unique extended structure on the inside of the capsid. On the outer surface, a polyproline helix structure, not seen previously in picornaviruses is present at the C terminus of VP1, a position where integrin binding motifs are found in some other picornaviruses. A peptide corresponding to this polyproline motif somewhat attenuates virus infectivity, presumably blocking host-cell attachment. This may guide cellular receptor identification.

ATR LEU Fuel and Burnable Absorber Neutronics Performance Optimization by Fuel Meat Thickness Variation

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

G. S. Chang

2007-09-01

The Advanced Test Reactor (ATR) is a high power density and high neutron flux research reactor operating in the United States. Powered with highly enriched uranium (HEU), the ATR has a maximum thermal power rating of 250 MWth. Because of the large test volumes located in high flux areas, the ATR is an ideal candidate for assessing the feasibility of converting an HEU driven reactor to a low-enriched core. The present work investigates the necessary modifications and evaluates the subsequent operating effects of this conversion. A detailed plate-by-plate MCNP ATR 1/8th core model was developed and validated for a fuelmore » cycle burnup comparison analysis. Using the current HEU U 235 enrichment of 93.0 % as a baseline, an analysis can be performed to determine the low-enriched uranium (LEU) density and U-235 enrichment required in the fuel meat to yield an equivalent K-eff between the HEU core and the LEU core versus effective full power days (EFPD). The MCNP ATR 1/8th core model will be used to optimize the U-235 loading in the LEU core, such that the differences in K-eff and heat flux profile between the HEU and LEU core can be minimized. The depletion methodology MCWO was used to calculate K-eff versus EFPDs in this paper. The MCWO-calculated results for the LEU cases with foil (U-10Mo) types demonstrated adequate excess reactivity such that the K-eff versus EFPDs plot is similar to the reference ATR HEU case. Each HEU fuel element contains 19 fuel plates with a fuel meat thickness of 0.508 mm. In this work, the proposed LEU (U-10Mo) core conversion case with a nominal fuel meat thickness of 0.508 mm and the same U-235 enrichment (15.5 wt%) can be used to optimize the radial heat flux profile by varying the fuel plate thickness from 0.254 to 0.457 mm at the inner 4 fuel plates (1-4) and outer 4 fuel plates (16-19). In addition, a 0.7g of burnable absorber Boron-10 was added in the inner and outer plates to reduce the initial excess reactivity, and the inner/outer heat flux more effectively. The optimized LEU relative radial fission heat flux profile is bounded by the reference ATR HEU case. However, to demonstrate that the LEU core fuel cycle performance can meet the Updated Final Safety Analysis Report (UFSAR) safety requirements, additional studies will be necessary to evaluate and compare safety parameters such as void reactivity and Doppler coefficients, control components worth (outer shim control cylinders, safety rods and regulating rod), and shutdown margins between the HEU and LEU cores.« less

Twin-Screw Extruder Development for the ITER Pellet Injection System

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

Meitner, Steven J; Baylor, Larry R; Combs, Stephen Kirk

The ITER pellet injection system is comprised of devices to form and accelerate pellets, and will be connected to inner wall guide tubes for fueling, and outer wall guide tubes for ELM pacing. An extruder will provide a stream of solid hydrogen isotopes to a secondary section, where pellets are cut and accelerated with a gas gun into the plasma. The ITER pellet injection system is required to provide a plasma fueling rate of 120 Pa-m3/s (900 mbar-L/s) and durations of up to 3000 s. The fueling pellets will be injected at a rate up to 10 Hz and pelletsmore » used to trigger ELMs will be injected at higher rates up to 20 Hz. A twin-screw extruder for the ITER pellet injection system is under development at the Oak Ridge National Laboratory. A one-fifth ITER scale prototype has been built and has demonstrated the production of a continuous solid deuterium extrusion. The 27 mm diameter, intermeshed, counter-rotating extruder screws are rotated at a rate up to ≈5 rpm. Deuterium gas is pre-cooled and liquefied and solidified in separate extruder barrels. The precooler consists of a deuterium gas filled copper coil suspended in a separate stainless steel vessel containing liquid nitrogen. The liquefier is comprised of a copper barrel connected to a Cryomech AL330 cryocooler, which has a machined helical groove surrounded by a copper jacket, through which the pre-cooled deuterium condenses. The lower extruder barrel is connected to a Cryomech GB-37 cryocooler to solidify the deuterium (at ≈15 K) before it is forced through the extruder die. The die forms the extrusion to a 3 mm x 4 mm rectangular cross section. Design improvements have been made to improve the pre-cooler and liquefier heat exchangers, to limit the loss of extrusion through gaps in the screws. This paper will describe the design improvements for the next iteration of the extruder prototype.« less

De novo design of a four-fold symmetric TIM-barrel protein with atomic-level accuracy

PubMed Central

Parmeggiani, Fabio; Velasco, D. Alejandro Fernandez; Höcker, Birte; Baker, David

2015-01-01

Despite efforts for over 25 years, de novo protein design has not succeeded in achieving the TIM-barrel fold. Here we describe the computational design of 4-fold symmetrical (β/α)8-barrels guided by geometrical and chemical principles. Experimental characterization of 33 designs revealed the importance of sidechain-backbone hydrogen bonding for defining the strand register between repeat units. The X-ray crystal structure of a designed thermostable 184-residue protein is nearly identical with the designed TIM-barrel model. PSI-BLAST searches do not identify sequence similarities to known TIM-barrel proteins, and sensitive profile-profile searches indicate that the design sequence is distant from other naturally occurring TIM-barrel superfamilies, suggesting that Nature has only sampled a subset of the sequence space available to the TIM-barrel fold. The ability to de novo design TIM-barrels opens new possibilities for custom-made enzymes. PMID:26595462

Suspended core subwavelength fibers: towards practical designs for low-loss terahertz guidance.

PubMed

Rozé, Mathieu; Ung, Bora; Mazhorova, Anna; Walther, Markus; Skorobogatiy, Maksim

2011-05-09

In this work we report two designs of subwavelength fibers packaged for practical terahertz wave guiding. We describe fabrication, modeling and characterization of microstructured polymer fibers featuring a subwavelength-size core suspended in the middle of a large porous outer cladding. This design allows convenient handling of the subwavelength fibers without distorting their modal profile. Additionally, the air-tight porous cladding serves as a natural enclosure for the fiber core, thus avoiding the need for a bulky external enclosure for humidity-purged atmosphere. Fibers of 5 mm and 3 mm in outer diameters with a 150 µm suspended solid core and a 900 µm suspended porous core respectively, were obtained by utilizing a combination of drilling and stacking techniques. Characterization of the fiber optical properties and the subwavelength imaging of the guided modes were performed using a terahertz near-field microscopy setup. Near-field imaging of the modal profiles at the fiber output confirmed the effectively single-mode behavior of such waveguides. The suspended core fibers exhibit transmission from 0.10 THz to 0.27 THz (larger core), and from 0.25 THz to 0.51 THz (smaller core). Due to the large fraction of power that is guided in the holey cladding, fiber propagation losses as low as 0.02 cm(-1) are demonstrated specifically for the small core fiber. Low-loss guidance combined with the core isolated from environmental perturbations make these all-dielectric fibers suitable for practical terahertz imaging and sensing applications. © 2011 Optical Society of America

Structural analysis and cross-protective efficacy of recombinant 87 kDa outer membrane protein (Omp87) of Pasteurella multocida serogroup B:2.

PubMed

Kumar, Abhinendra; Yogisharadhya, Revanaiah; Ramakrishnan, Muthannan A; Viswas, K N; Shivachandra, Sathish B

2013-12-01

Pasteurella multocida serogroup B:2, a causative agent of haemorrhagic septicaemia (HS) in cattle and buffalo especially in tropical regions of Asian and African countries, is known to possess several outer membrane proteins (OMPs) as immunogenic antigens. In the present study, omp87 gene encoding for 87 kDa OMP (Omp87) protein of P. multocida serogroup B:2 strain P52, has been amplified (∼2304 bp), cloned in to pET32a vector and over-expressed in recombinant Escherichia coli as fusion protein. The recombinant Omp87 protein (∼102 kDa) including N-terminus hexa-histidine tag was purified under denaturing condition. Immunization of mice with rOmp87 resulted in increased antigen specific IgG titres in serum and provided protection of 66.6 and 83.3% following homologous (B:2) and heterologous (A:1) challenge, respectively. A homology model of Omp87 revealed the presence of two distinct domains; N-terminal domain with four POTRA repeats in the periplasmic space and a pore forming C-terminal β-barrel domain (β1- β16) in the outer membrane of P. multocida, which belong to Omp85-TpsB transporter superfamily of OMPs. The study indicated the potential possibilities to use rOmp87 protein along with suitable adjuvant in developing subunit vaccine for haemorrhagic septicaemia and pasteurellosis in livestock. Copyright © 2013 Elsevier Ltd. All rights reserved.

Purification, crystallization and characterization of the Pseudomonas outer membrane protein FapF, a functional amyloid transporter.

PubMed

Rouse, Sarah L; Hawthorne, Wlliam J; Lambert, Sebastian; Morgan, Marc L; Hare, Stephen A; Matthews, Stephen

2016-12-01

Bacteria often produce extracellular amyloid fibres via a multi-component secretion system. Aggregation-prone, unstructured subunits cross the periplasm and are secreted through the outer membrane, after which they self-assemble. Here, significant progress is presented towards solving the high-resolution crystal structure of the novel amyloid transporter FapF from Pseudomonas, which facilitates the secretion of the amyloid-forming polypeptide FapC across the bacterial outer membrane. This represents the first step towards obtaining structural insight into the products of the Pseudomonas fap operon. Initial attempts at crystallizing full-length and N-terminally truncated constructs by refolding techniques were not successful; however, after preparing FapF 106-430 from the membrane fraction, reproducible crystals were obtained using the sitting-drop method of vapour diffusion. Diffraction data have been processed to 2.5 Å resolution. These crystals belonged to the monoclinic space group C121, with unit-cell parameters a = 143.4, b = 124.6, c = 80.4 Å, α = γ = 90, β = 96.32° and three monomers in the asymmetric unit. It was found that the switch to complete detergent exchange into C8E4 was crucial for forming well diffracting crystals, and it is suggested that this combined with limited proteolysis is a potentially useful protocol for membrane β-barrel protein crystallography. The three-dimensional structure of FapF will provide invaluable information on the mechanistic differences of biogenesis between the curli and Fap functional amyloid systems.

Sulfur in Earth's Mantle and Its Behavior During Core Formation

NASA Technical Reports Server (NTRS)

Chabot, Nancy L.; Righter,Kevin

2006-01-01

The density of Earth's outer core requires that about 5-10% of the outer core be composed of elements lighter than Fe-Ni; proposed choices for the "light element" component of Earth's core include H, C, O, Si, S, and combinations of these elements [e.g. 1]. Though samples of Earth's core are not available, mantle samples contain elemental signatures left behind from the formation of Earth's core. The abundances of siderophile (metal-loving) elements in Earth's mantle have been used to gain insight into the early accretion and differentiation history of Earth, the process by which the core and mantle formed, and the composition of the core [e.g. 2-4]. Similarly, the abundance of potential light elements in Earth's mantle could also provide constraints on Earth's evolution and core composition. The S abundance in Earth's mantle is 250 ( 50) ppm [5]. It has been suggested that 250 ppm S is too high to be due to equilibrium core formation in a high pressure, high temperature magma ocean on early Earth and that the addition of S to the mantle from the subsequent accretion of a late veneer is consequently required [6]. However, this earlier work of Li and Agee [6] did not parameterize the metalsilicate partitioning behavior of S as a function of thermodynamic variables, limiting the different pressure and temperature conditions during core formation that could be explored. Here, the question of explaining the mantle abundance of S is revisited, through parameterizing existing metal-silicate partitioning data for S and applying the parameterization to core formation in Earth.

An improved method for constructing and selectively silanizing double-barreled, neutral liquid-carrier, ion-selective microelectrodes

PubMed Central

Deveau, Jason S.T.; Grodzinski, Bernard

2005-01-01

We describe an improved, efficient and reliable method for the vapour-phase silanization of multi-barreled, ion-selective microelectrodes of which the silanized barrel(s) are to be filled with neutral liquid ion-exchanger (LIX). The technique employs a metal manifold to exclusively and simultaneously deliver dimethyldichlorosilane to only the ion-selective barrels of several multi-barreled microelectrodes. Compared to previously published methods the technique requires fewer procedural steps, less handling of individual microelectrodes, improved reproducibility of silanization of the selected microelectrode barrels and employs standard borosilicate tubing rather than the less-conventional theta-type glass. The electrodes remain stable for up to 3 weeks after the silanization procedure. The efficacy of a double-barreled electrode containing a proton ionophore in the ion-selective barrel is demonstrated in situ in the leaf apoplasm of pea (Pisum) and sunflower (Helianthus). Individual leaves were penetrated to depth of ~150 μm through the abaxial surface. Microelectrode readings remained stable after multiple impalements without the need for a stabilizing PVC matrix. PMID:16136222

Electrocatalysts having gold monolayers on platinum nanoparticle cores, and uses thereof

DOEpatents

Adzic, Radoslav; Zhang, Junliang

2010-04-27

The invention relates to gold-coated particles useful as fuel cell electrocatalysts. The particles are composed of an electrocatalytically active core at least partially encapsulated by an outer shell of gold or gold alloy. The invention more particularly relates to such particles having a noble metal-containing core, and more particularly, a platinum or platinum alloy core. In other embodiments, the invention relates to fuel cells containing these electrocatalysts and methods for generating electrical energy therefrom.

A core handling device for the Mars Sample Return Mission

NASA Technical Reports Server (NTRS)

Gwynne, Owen

1989-01-01

A core handling device for use on Mars is being designed. To provide a context for the design study, it was assumed that a Mars Rover/Sample Return (MRSR) Mission would have the following characteristics: a year or more in length; visits by the rover to 50 or more sites; 100 or more meter-long cores being drilled by the rover; and the capability of returning about 5 kg of Mars regolith to Earth. These characteristics lead to the belief that in order to bring back a variegated set of samples that can address the range of scientific objetives for a MRSR mission to Mars there needs to be considerable analysis done on board the rover. Furthermore, the discrepancy between the amount of sample gathered and the amount to be returned suggests that there needs to be some method of choosing the optimal set of samples. This type of analysis will require pristine material-unaltered by the drilling process. Since the core drill thermally and mechanically alters the outer diameter (about 10 pct) of the core sample, this outer area cannot be used. The primary function of the core handling device is to extract subsamples from the core and to position these subsamples, and the core itself if needed, with respect to the various analytical instruments that can be used to perform these analyses.

A model for osmium isotopic evolution of metallic solids at the core-mantle boundary

NASA Astrophysics Data System (ADS)

Humayun, Munir

2011-03-01

Some plumes are thought to originate at the core-mantle boundary, but geochemical evidence of core-mantle interaction is limited to Os isotopes in samples from Hawaii, Gorgona (89 Ma), and Kostomuksha (2.7 Ga). The Os isotopes have been explained by physical entrainment of Earth's liquid outer core into mantle plumes. This model has come into conflict with geophysical estimates of the timing of core formation, high-pressure experimental determinations of the solid metal-liquid metal partition coefficients (D), and the absence of expected 182W anomalies. A new model is proposed where metallic liquid from the outer core is partially trapped in a compacting cumulate pile of Fe-rich nonmetallic precipitates (FeO, FeS, Fe3Si, etc.) at the top of the core and undergoes fractional crystallization precipitating solid metal grains, followed by expulsion of the residual metallic liquid back to the outer core. The Os isotopic composition of the solids and liquids in the cumulate pile is modeled as a function of the residual liquid remaining and the emplacement age using 1 bar D values, with variable amounts of oxygen (0-10 wt %) as the light element. The precipitated solids evolve Os isotope compositions that match the trends for Hawaii (at an emplacement age of 3.5-4.5 Ga; 5%-10% oxygen) and Gorgona (emplacement age < 1.5 Ga; 0%-5% oxygen). The Fe-rich matrix of the cumulate pile dilutes the precipitated solid metal decoupling the Fe/Mn ratio from Os and W isotopes. The advantages to using precipitated solid metal as the Os host include a lower platinum group element and Ni content to the mantle source region relative to excess iron, miniscule anomalies in 182W (<0.1 ɛ), and no effects for Pb isotopes, etc. A gradual thermomechanical erosion of the cumulate pile results in incorporation of this material into the base of the mantle, where mantle plumes subsequently entrain it. Fractional crystallization of metallic liquids within the CMB provides a consistent explanation of both Os isotope correlations, Os-W isotope systematics, and Fe/Mn evidence for core-mantle interaction over the entire Hawaiian source.

Astringency, bitterness and color changes in dry red wines before and during oak barrel aging: An updated phenolic perspective review.

PubMed

Li, Si-Yu; Duan, Chang-Qing

2018-01-30

To understand effects of using oak barrels on the astringency, bitterness and color of dry red wines, phenolic reactions in wines before and after barrel aging are reviewed in this paper, which has been divided into three sections. The first section includes an introduction to chemical reactivities of grape-derived phenolic compounds, a summary of the phenolic reactions that occur in dry red wines before barrel aging, and a discussion of the effects of these reactions on wine astringency, bitterness and color. The second section introduces barrel types that determine the oak barrel constituents in wines (primarily oak aldehydes and ellagitannins) and presents reactions between the oak constituents and grape-derived phenolic compounds that may modulate wine astringency, bitterness and color. The final section illustrates the chemical differences between basic oxidation and over-oxidation in wines, discusses oxygen consumption kinetics in wines during barrel aging by comparing different oxygen consumption kinetics observed previously by others, and speculates on the possible preliminary phenolic reactions that occur in dry red wines during oak barrel aging that soften tannins and stabilize pigments via basic oxidation. Additionally, sulfur dioxide (SO 2 ) addition during barrel aging and suitability of adopting oak barrels for aging wines are briefly discussed.

Axial flow positive displacement worm gas generator

NASA Technical Reports Server (NTRS)

Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor); Murrow, Kurt David (Inventor)

2010-01-01

An axial flow positive displacement engine has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first, second, and third sections of a core assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first, second, and third twist slopes in the first, second, and third sections respectively. The first twist slopes are less than the second twist slopes and the third twist slopes are less than the second twist slopes. A combustor section extends axially downstream through at least a portion of the second section.

Rotational Splittings of Acoustic Modes in an Experimental Model of a Planetary Core

NASA Astrophysics Data System (ADS)

Adams, M. M.; Stone, D.; Lathrop, D. P.

2014-12-01

Planetary zonal flows can be probed in principle using the tools of helioseismology. We explore this technique using laboratory experiments where the measurement of zonal flows is also of geophysical relevance. The experiments are carried out in a device with a geometry similar to that of Earth's core. It consists of a 60 cm diameter outer spherical shell concentric with a 20 cm diameter inner sphere. Air between the inner sphere and outer shell is used as the working fluid. A turbulent shear flow is driven in the air by independently rotating the inner sphere and outer shell. Acoustic modes are excited in the vessel with a speaker, and microphones are used to measure the rotational splittings of these modes. The radial profile of azimuthal velocities is inferred from these splittings, in an approach analogous to that used in helioseismology to determine solar velocity profiles. By varying the inner and outer rotation rates, different turbulent states can be investigated. Comparison is made to previous experimental investigations of turbulent spherical Couette flow. These experiments also serve as a test of this diagnostic, which may be used in the future in liquid sodium experiments, providing information on zonal flows in hydromagnetic experiments.

15 CFR 240.1 - Title of act.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE STANDARDS FOR BARRELS BARRELS AND OTHER CONTAINERS FOR LIME... U.S.C. 237-242), entitled “An Act to standardize lime barrels,” shall be known and referred to as the “Standard Lime-Barrel Act.” ...

Structural response of 1/20-scale models of the Clinch River Breeder Reactor to a simulated hypothetical core disruptive accident. Technical report 4

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

Romander, C. M.; Cagliostro, D. J.

Five experiments were performed to help evaluate the structural integrity of the reactor vessel and head design and to verify code predictions. In the first experiment (SM 1), a detailed model of the head was loaded statically to determine its stiffness. In the remaining four experiments (SM 2 to SM 5), models of the vessel and head were loaded dynamically under a simulated 661 MW-sec hypothetical core disruptive accident (HCDA). Models SM 2 to SM 4, each of increasing complexity, systematically showed the effects of upper internals structures, a thermal liner, core support platform, and torospherical bottom on vessel response.more » Model SM 5, identical to SM 4 but more heavily instrumented, demonstrated experimental reproducibility and provided more comprehensive data. The models consisted of a Ni 200 vessel and core barrel, a head with shielding and simulated component masses, an upper internals structure (UIS), and, in the more complex models SM 4 and SM 5, a Ni 200 thermal liner and core support structure. Water simulated the liquid sodium coolant and a low-density explosive simulated the HCDA loads.« less

Reduction of Gun Erosion and Correlation of Gun Erosion Measurements

NASA Technical Reports Server (NTRS)

Bogdanoff, Dave; Wercinski, Paul (Technical Monitor)

1997-01-01

Gun barrel erosion is serious problem with two-stage light gas guns. Excessive barrel erosion can lead to poor or failed launches and frequent barrel changes, with the corresponding down time. Also, excessive barrel erosion can limit the maximum velocity obtainable by loading down the hydrogen working gas with eroded barrel material. Guided by a CFD code, the operating conditions of the Ames 0.5-inch gun were modified to reduce barrel erosion. The changes implemented included: (1) reduction in the piston mass, powder mass and hydrogen fill pressure; and (2) reduction in pump tube volume, while maintaining hydrogen mass. The latter change was found, in particular, to greatly reduce barrel erosion. For muzzle velocity ranges of 6.1 - 6.9 km/sec, the barrel erosion was reduced by a factor of 10. Even for the higher muzzle velocity range of 7.0 - 8.2 km/sec, the barrel erosion was reduced by a factor of 4. Gun erosion data from the Ames 0.5-inch, 1.0-inch, and 1.5-inch guns operated over a wide variety of launch conditions was examined and it was found that this data could be correlated using four different parameters: normalized powder charge energy, normalized hydrogen energy density, normalized pump tube volume and barrel diameter. The development of the correlation and the steps used to collapse the experimental data are presented. Over a certain parameter range in the correlation developed, the barrel erosion per shot is found to increase very rapidly. The correlation should prove useful in the selection of gun operating conditions and the design of new guns. Representative shapes of eroded gun barrels are also presented.

Preliminary study of oaklins, a new class of brick-red catechinpyrylium pigments resulting from the reaction between catechin and wood aldehydes.

PubMed

Sousa, Carlos; Mateus, Nuno; Perez-Alonso, Joaquín; Santos-Buelga, Celestino; Freitas, Victor de

2005-11-16

Several structurally related pigments were found to result from the reaction between catechin and coniferaldehyde/sinapaldehyde extracted from oak wood. Their structures were tentatively identified by mass spectrometry, and their formation was studied in different pH and temperature conditions for several days. They were all found to have a characteristic catechinpyrylium core, thereby constituting a new class of compounds named as oaklins. One of the main oaklins was also detected in a commercial table red wine aged in oak barrels.

Synthesis of triaxial LiFePO4 nanowire with a VGCF core column and a carbon shell through the electrospinning method.

PubMed

Hosono, Eiji; Wang, Yonggang; Kida, Noriyuki; Enomoto, Masaya; Kojima, Norimichi; Okubo, Masashi; Matsuda, Hirofumi; Saito, Yoshiyasu; Kudo, Tetsuichi; Honma, Itaru; Zhou, Haoshen

2010-01-01

A triaxial LiFePO4 nanowire with a multi wall carbon nanotube (VGCF:Vapor-grown carbon fiber) core column and an outer shell of amorphous carbon was successfully synthesized through the electrospinning method. The carbon nanotube core oriented in the direction of the wire played an important role in the conduction of electrons during the charge-discharge process, whereas the outer amorphous carbon shell suppressed the oxidation of Fe2+. An electrode with uniformly dispersed carbon and active materials was easily fabricated via a single process by heating after the electrospinning method is applied. Mossbauer spectroscopy for the nanowire showed a broadening of the line width, indicating a disordered coordination environment of the Fe ion near the surface. The electrospinning method was proven to be suitable for the fabrication of a triaxial nanostructure.

Convective overshooting in the evolution of very massive stars

NASA Technical Reports Server (NTRS)

Stothers, R.; Chin, C.-W.

1981-01-01

Possible convective overshooting in stars of 30-120 solar masses are considered, including a merger between the convective core and the intermediate zone, and penetration by the outer convection zone into the hydrogen-shell region when the star is a supergiant. Convective mixing between the core and inner envelopes is found to lead to a brief renewal of hydrogen burning in the core, and a moderate widening of the main sequence bond in the H-R diagram. Deep penetration by the outer convection zone is found to force the star out of the red supergiant configuration and into a configuration near the main sequence. This would account for the apparent spread of the uppermost part of the main sequence and the concentration of luminous supergiants towards earlier spectral types. In addition, heavy mass loss need not be assumed to achieve the points of agreement, and are tentatively considered unimportant from an evolutionary point of view.

Modeling of rapid shutdown in the DIII-D tokamak by core deposition of high-Z material

DOE PAGES

Izzo, Valerie A.; Parks, Paul B.

2017-06-22

MHD modeling of shell-pellet injection for disruption mitigation is carried out under the assumption of idealized delivery of the radiating payload to the core, neglecting the physics of shell ablation. The shell pellet method is designed to produce an inside-out thermal quench in which core thermal heat is radiated while outer flux surfaces remain intact, protecting the divertor from large conducted heat loads. In the simulation, good outer surfaces remain until the thermal quench is nearly complete, and a high radiated energy fraction is achieved. As a result, when the outermost surfaces are destroyed, runaway electron test orbits indicate thatmore » the rate of runaway electron loss is very fast compared with prior massive gas injection simulations, which is attributed to the very different current profile evolution that occurs with central cooling.« less

Measurement and Analysis of Structural Integrity of Reactor Core Support Structure in Pressurized Water Reactor (PWR) Plant

NASA Astrophysics Data System (ADS)

Ansari, Saleem A.; Haroon, Muhammad; Rashid, Atif; Kazmi, Zafar

2017-02-01

Extensive calculation and measurements of flow-induced vibrations (FIV) of reactor internals were made in a PWR plant to assess the structural integrity of reactor core support structure against coolant flow. The work was done to meet the requirements of the Fukushima Response Action Plan (FRAP) for enhancement of reactor safety, and the regulatory guide RG-1.20. For the core surveillance measurements the Reactor Internals Vibration Monitoring System (IVMS) has been developed based on detailed neutron noise analysis of the flux signals from the four ex-core neutron detectors. The natural frequencies, displacement and mode shapes of the reactor core barrel (CB) motion were determined with the help of IVMS. The random pressure fluctuations in reactor coolant flow due to turbulence force have been identified as the predominant cause of beam-mode deflection of CB. The dynamic FIV calculations were also made to supplement the core surveillance measurements. The calculational package employed the computational fluid dynamics, mode shape analysis, calculation of power spectral densities of flow & pressure fields and the structural response to random flow excitation forces. The dynamic loads and stiffness of the Hold-Down Spring that keeps the core structure in position against upward coolant thrust were also determined by noise measurements. Also, the boron concentration in primary coolant at any time of the core cycle has been determined with the IVMS.

Motion of the Mantle in the Translational Modes of the Earth and Mercury

NASA Technical Reports Server (NTRS)

Grinfeld, Pavel; Wisdom, Jack

2005-01-01

Slichter modes refer to the translational motion of the inner core with respect to the outer core and the mantle. The polar Slichter mode is the motion of the inner core along the axis of rotation. Busse presented an analysis of the polar mode which yielded an expression for its period. Busse's analysis included the assumption that the mantle was stationary. This approximation is valid for planets with small inner cores, such as the Earth whose inner core is about 1/60 of the total planet mass. On the other hand, many believe that Mercury's core may be enormous. If so, the motion of the mantle should be expected to produce a significant effect. We present a formal framework for including the motion of the mantle in the analysis of the translational motion of the inner core. We analyze the effect of the motion of the mantle on the Slichter modes for a non-rotating planet with an inner core of arbitrary size. We omit the effects of viscosity in the outer core, magnetic effects, and solid tides. Our approach is perturbative and is based on a linearization of Euler's equations for the motion of the fluid and Newton's second law for the motion of the inner core. We find an analytical expression for the period of the Slichter mode. Our result agrees with Busse's in the limiting case of small inner core. We present the unexpected result that even for Mercury the motion of the mantle does not significantly change the period of oscillation.

Preparation of Geophysical Fluid Flow Experiments ( GeoFlow ) in the Fluid Science Laboratory on ISS

NASA Astrophysics Data System (ADS)

Egbers, C.

The ,,GeoFlow" is an ESA experiment planned for the Fluid Science Laboratory on ISS under the scientific coordination (PI) of the Department of Aerodynamics and Fluidmechanics (LAS) at the Brandenburg Technical University (BTU) of Cottbus, Germany. The objective of the experiment is to study thermal convection in the gap between two concentric rotating (full) spheres. A central symmetric force field similar to the gravity field acting on planets can be produced by applying a high voltage between inner and outer sphere using the dielectrophoretic effect (rotating capacitor). To counter the unidirectional gravity under terrestrial conditions, this experiment requires a microgravity environment. The parameters of the experiment are chosen in analogy to the thermal convective motions in the outer core of the Earth. In analogy to geophysical motions in the Earth's liquid core the exp eriment can rotate as solid body as well as differential (inner to outer). Thermal convection is produced by heating the inner sphere and cooling the outer ones. Furtheron, the variation of radius ratio between inner and outer sphere is foreseen as a parameter variation. The flows to be investigated will strongly depend on the gap width and on the Prandtl number. Results of preparatory experiments and numerical simulation of the space experiment will be presented. Funding from DLR under grant 50 WM 0122 is greatfully ackwnoledged.

Vesicular glutamate transporters VGLUT1 and VGLUT2 in the developing mouse barrel cortex.

PubMed

Liguz-Lecznar, M; Skangiel-Kramska, J

2007-04-01

Three vesicular glutamate transporters have been identified in mammals. Two of them, VGLUT1 and VGLUT2, define the glutamatergic phenotype and their distribution in the brain is almost complementary. In the present study we examined the distribution and expression levels of these two VGLUTs during postnatal development of the mouse barrel cortex. We also investigated changes in the localization of VGLUT1 and VGLUT2 within particular compartments of the barrel field (barrels/septa) during its development. We found differences in the time course of developmental expression, with VGLUT1 peaking around P14, while VGLUT2 increased gradually until adulthood. Over the examined period (P3 - adult) both transporters had stronger expression in the barrel interiors, and in this compartment VGLUT2 dominated, whereas in the inter-barrel septa VGLUT1 dominated over VGLUT2. Furthermore, we found that some nerve terminals in the barrel cortex coexpressed both transporters until adulthood. Colocalization was observed within the barrels, but not within the septa.

Method for manufacturing magnetohydrodynamic electrodes

DOEpatents

Killpatrick, Don H.; Thresh, Henry R.

1982-01-01

A method of manufacturing electrodes for use in a magnetohydrodynamic (MHD) generator comprising the steps of preparing a billet having a core 10 of a first metal, a tubular sleeve 12 of a second metal, and an outer sheath 14, 16, 18 of an extrusile metal; evacuating the space between the parts of the assembled billet; extruding the billet; and removing the outer jacket 14. The extruded bar may be made into electrodes by cutting and bending to the shape required for an MDH channel frame. The method forms a bond between the first metal of the core 10 and the second metal of the sleeve 12 strong enough to withstand a hot and corrosive environment.

Europa's differentiated internal structure: inferences from four Galileo encounters.

PubMed

Anderson, J D; Schubert, G; Jacobson, R A; Lau, E L; Moore, W B; Sjogren, W L

1998-09-25

Radio Doppler data from four encounters of the Galileo spacecraft with the jovian moon Europa have been used to refine models of Europa's interior. Europa is most likely differentiated into a metallic core surrounded by a rock mantle and a water ice-liquid outer shell, but the data cannot eliminate the possibility of a uniform mixture of dense silicate and metal beneath the water ice-liquid shell. The size of a metallic core is uncertain because of its unknown composition, but it could be as large as about 50 percent of Europa's radius. The thickness of Europa's outer shell of water ice-liquid must lie in the range of about 80 to 170 kilometers.

FAILURE OF A NEUTRINO-DRIVEN EXPLOSION AFTER CORE-COLLAPSE MAY LEAD TO A THERMONUCLEAR SUPERNOVA

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

Kushnir, Doron; Katz, Boaz, E-mail: kushnir@ias.edu

We demonstrate that ∼10 s after the core-collapse of a massive star, a thermonuclear explosion of the outer shells is possible for some (tuned) initial density and composition profiles, assuming that the neutrinos failed to explode the star. The explosion may lead to a successful supernova, as first suggested by Burbidge et al. We perform a series of one-dimensional (1D) calculations of collapsing massive stars with simplified initial density profiles (similar to the results of stellar evolution calculations) and various compositions (not similar to 1D stellar evolution calculations). We assume that the neutrinos escaped with a negligible effect on themore » outer layers, which inevitably collapse. As the shells collapse, they compress and heat up adiabatically, enhancing the rate of thermonuclear burning. In some cases, where significant shells of mixed helium and oxygen are present with pre-collapsed burning times of ≲100 s (≈10 times the free-fall time), a thermonuclear detonation wave is ignited, which unbinds the outer layers of the star, leading to a supernova. The energy released is small, ≲10{sup 50} erg, and negligible amounts of synthesized material (including {sup 56}Ni) are ejected, implying that these 1D simulations are unlikely to represent typical core-collapse supernovae. However, they do serve as a proof of concept that the core-collapse-induced thermonuclear explosions are possible, and more realistic two-dimensional and three-dimensional simulations are within current computational capabilities.« less

15 CFR 240.2 - Application.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE STANDARDS FOR BARRELS BARRELS AND OTHER CONTAINERS FOR LIME... to lime in barrels, or other containers packed, sold, or offered for sale for shipment from any State...; and to lime in containers of less capacity than the standard small barrel sold in interstate or...

Secular changes of LOD associated with a growth of the inner core

NASA Astrophysics Data System (ADS)

Denis, C.; Rybicki, K. R.; Varga, P.

2006-05-01

From recent estimates of the age of the inner core based on the theory of thermal evolution of the core, we estimate that nowadays the growth of the inner core may perhaps contribute to the observed overall secular increase of LOD caused mainly by tidal friction (i.e., 1.72 ms per century) by a relative decrease of 2 to 7 μs per century. Another, albeit much less plausible, hypothesis is that crystallization of the inner core does not produce any change of LOD, but makes the inner core rotate differentially with respect to the outer core and mantle.

Response sensitivity of barrel neuron subpopulations to simulated thalamic input.

PubMed

Pesavento, Michael J; Rittenhouse, Cynthia D; Pinto, David J

2010-06-01

Our goal is to examine the relationship between neuron- and network-level processing in the context of a well-studied cortical function, the processing of thalamic input by whisker-barrel circuits in rodent neocortex. Here we focus on neuron-level processing and investigate the responses of excitatory and inhibitory barrel neurons to simulated thalamic inputs applied using the dynamic clamp method in brain slices. Simulated inputs are modeled after real thalamic inputs recorded in vivo in response to brief whisker deflections. Our results suggest that inhibitory neurons require more input to reach firing threshold, but then fire earlier, with less variability, and respond to a broader range of inputs than do excitatory neurons. Differences in the responses of barrel neuron subtypes depend on their intrinsic membrane properties. Neurons with a low input resistance require more input to reach threshold but then fire earlier than neurons with a higher input resistance, regardless of the neuron's classification. Our results also suggest that the response properties of excitatory versus inhibitory barrel neurons are consistent with the response sensitivities of the ensemble barrel network. The short response latency of inhibitory neurons may serve to suppress ensemble barrel responses to asynchronous thalamic input. Correspondingly, whereas neurons acting as part of the barrel circuit in vivo are highly selective for temporally correlated thalamic input, excitatory barrel neurons acting alone in vitro are less so. These data suggest that network-level processing of thalamic input in barrel cortex depends on neuron-level processing of the same input by excitatory and inhibitory barrel neurons.

Drilling into Magma: Experiences at Kīlauea Iki Lava Lake, Hawaii

NASA Astrophysics Data System (ADS)

Helz, R. L.

2017-12-01

Several historic lava lakes (1959 Kīlauea Iki, 1963 Alae, and 1965 Makaopuhi) were drilled in the 20th century, and molten core recovered from them. Kīlauea Iki lava lake, the most extensively studied, was drilled in 1960-62, 1967, 1965, 1976, 1979, 1981 and 1988. A total of 1400 m feet of core was recovered, about 210 m of which was partially molten. The melt fraction varied from near zero to 40-45% by volume, with higher fractions in glassy ooze from below the crust/melt interface. Most of the 1960-1979 drill holes terminated in pre-existing melt-rich internal differentiates; the later (1981, 1988) drill holes were mostly stopped arbitrarily. When melt was reached and the string backed off to wireline the last interval of core, black glassy ooze immediately moved up the borehole. Repeated re-entry and ooze recovery never exhausted the melt-rich sources. The first deep hole that did not hit melt was KI79-1, which was stopped at 62.2 m after recovering 12 m of molten mush. Here the uncased drill hole backfilled not with black glassy ooze but with olivine-rich, partly crystalline mush. The first redrilled core (recovered between 50.8 and 53.9 m), which moved up over a period of 16 days after termination of the original hole, underwent extensive separation of melt from crystals as it flowed upward. After this interval was pulled, drilling resumed with the bottom of the hole at 52.9 m, and uniform olivine-rich mush was recovered from 52.9-54.25 m. Drilling resumed once more at 52.9 m and a further 3 m of ooze recovered. The bit reached a depth of 55.4 m when the core barrel was full, suggesting that the crystal-rich mush was rising into the core barrel spontaneously during drilling. The three cores recovered in reentering KI79-1 show the effect of unloading the confining pressure on mush layers, with melt moving toward the low-pressure area (the bottom of the hole) relative to crystals. All of the crystal-rich mushes are more melt-rich than the original core, with elevated TiO2, K2O and P2O5 levels at the same bulk MgO content. Grain-to-grain contacts were progressively eroded in the melt-inflated mushes, so that the mushes had no internal cohesion. Although their melt contents never reached 50% by volume, they were extremely mobile, rising into the drill hole in minutes rather than the days required for the initial backfilling of the hole.

Atmospheric Mining in the Outer Solar System:. [Aerial Vehicle Reconnaissance and Exploration Options

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan A.

2014-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and hydrogen (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues. While capturing 3He, large amounts of hydrogen and 4He are produced. With these two additional gases, the potential for fueling small and large fleets of additional exploration and exploitation vehicles exists. Additional aerospacecraft or other aerial vehicles (UAVs, balloons, rockets, etc.) could fly through the outer planet atmospheres, for global weather observations, localized storm or other disturbance investigations, wind speed measurements, polar observations, etc. Deep-diving aircraft (built with the strength to withstand many atmospheres of pressure) powered by the excess hydrogen or helium 4 may be designed to probe the higher density regions of the gas giants. Outer planet atmospheric properties, atmospheric storm data, and mission planning for future outer planet UAVs are presented.

Hubble Space Telescope survey of the Perseus cluster - III. The effect of local environment on dwarf galaxies

NASA Astrophysics Data System (ADS)

Penny, Samantha J.; Conselice, Christopher J.; de Rijcke, Sven; Held, Enrico V.; Gallagher, John S.; O'Connell, Robert W.

2011-01-01

We present the results of a Hubble Space Telescope (HST) study of dwarf galaxies in the outer regions of the nearby rich Perseus cluster, down to MV=-12, and compare these with the dwarf population in the cluster core from our previous HST imaging. In this paper, we examine how properties such as the colour-magnitude relation, structure and morphology are affected by environment for the lowest mass galaxies. Dwarf galaxies are excellent tracers of the effects of environment due to their low masses, allowing us to derive their environmentally based evolution, which is more subtle in more massive galaxies. We identify 11 dwarf elliptical (dE) and dwarf spheroidal (dSph) galaxies in the outer regions of Perseus, all of which are previously unstudied. We measure the (V-I)0 colours of our newly discovered dEs, and find that these dwarfs lie on the same red sequence as those in the cluster core. The morphologies of these dwarfs are examined by quantifying their light distributions using concentration, asymmetry and clumpiness (CAS) parameters, and we find that dEs in the cluster outskirts are on average more disturbed than those in the core, with = 0.13 ± 0.09 and = 0.18 ± 0.08, compared to = 0.02 ± 0.04, = 0.01 ± 0.07 for those in the core. Based on these results, we infer that these objects are `transition dwarfs', likely in the process of transforming from late-type to early-type galaxies as they infall into the cluster, with their colours transforming before their structures. When we compare the number counts for both the core and outer regions of the cluster, we find that below MV=-12, the counts in the outer regions of the cluster exceed those in the core. This is evidence that in the very dense region of the cluster, dwarfs are unable to survive unless they are sufficiently massive to prevent their disruption by the cluster potential and interactions with other galaxies. Based on observations made with the NASA/ESA HST, obtained (from the Data Archive) at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs GO-10201 and GO-10789