(2E)-1-(4,4′′-Difluoro-5′-meth­oxy-1,1′:3′,1′′-terphenyl-4′-yl)-3-(2-fluoro­phen­yl)prop-2-en-1-one

PubMed Central

Fun, Hoong-Kun; Loh, Wan-Sin; Samshuddin, S.; Narayana, B.; Sarojini, B. K.

2012-01-01

In the title compound, C28H19F3O2, the central benzene ring forms dihedral angles of 48.69 (6), 60.93 (6) and 42.06 (6)° with the fluoro­benzene rings. In the crystal, inter­molecular C—H⋯O and C—H⋯F hydrogen bonds link the mol­ecules, forming an undulating two-dimensional network parallel to the bc plane. C—H⋯π inter­actions further consolidate the crystal packing. PMID:22807850

Planetary Rings

NASA Astrophysics Data System (ADS)

Esposito, Larry W.

2011-07-01

Preface; 1. Introduction: the allure of ringed planets; 2. Studies of planetary rings 1610-2004; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-Body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Neptune's partial rings; 13. Jupiter's ring-moon system after Galileo; 14. Ring photometry; 15. Dusty rings; 16. Cassini observations; 17. Summary: the big questions; Glossary; References; Index.

Design and synthesis of aryl ether and sulfone hydroxamic acids as potent histone deacetylase (HDAC) inhibitors.

PubMed

Pabba, Chittari; Gregg, Brian T; Kitchen, Douglas B; Chen, Zhen Jia; Judkins, Angela

2011-01-01

A series of novel hydroxamic acid based histone deacetylases (HDAC) inhibitors with aryl ether and aryl sulfone residues at the terminus of a substituted, unsaturated 5-carbon spacer moiety have been synthesized for the first time and evaluated. Compounds with meta- and para-substitution on the aryl ring of ether hydroxamic acids 19c, 20c, 19e, 19f and 19g are potent HDAC inhibitors with activities at low nanomolar levels. Copyright © 2010 Elsevier Ltd. All rights reserved.

Structure–function analysis and genetic interactions of the SmG, SmE, and SmF subunits of the yeast Sm protein ring

PubMed Central

Schwer, Beate; Kruchten, Joshua; Shuman, Stewart

2016-01-01

A seven-subunit Sm protein ring forms a core scaffold of the U1, U2, U4, and U5 snRNPs that direct pre-mRNA splicing. Using human snRNP structures to guide mutagenesis in Saccharomyces cerevisiae, we gained new insights into structure–function relationships of the SmG, SmE, and SmF subunits. An alanine scan of 19 conserved amino acids of these three proteins, comprising the Sm RNA binding sites or inter-subunit interfaces, revealed that, with the exception of Arg74 in SmF, none are essential for yeast growth. Yet, for SmG, SmE, and SmF, as for many components of the yeast spliceosome, the effects of perturbing protein–RNA and protein–protein interactions are masked by built-in functional redundancies of the splicing machine. For example, tests for genetic interactions with non-Sm splicing factors showed that many benign mutations of SmG, SmE, and SmF (and of SmB and SmD3) were synthetically lethal with null alleles of U2 snRNP subunits Lea1 and Msl1. Tests of pairwise combinations of SmG, SmE, SmF, SmB, and SmD3 alleles highlighted the inherent redundancies within the Sm ring, whereby simultaneous mutations of the RNA binding sites of any two of the Sm subunits are lethal. Our results suggest that six intact RNA binding sites in the Sm ring suffice for function but five sites may not. PMID:27417296

Supramolecular architectures with π-acidic 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine cavities: role of anion-π interactions in the remarkable stability of Fe(II) metallacycles in solution.

PubMed

Chifotides, Helen T; Giles, Ian D; Dunbar, Kim R

2013-02-27

The comprehensive investigation reported herein provides compelling evidence that anion-π interactions are the main driving force in the formation of self-assembled Fe(II)-templated metallacycles with bptz [3,6-bis(2-pyridyl)-1,2,4,5-tetrazine] in high yields. It was demonstrated by X-ray crystallography, (1)H NMR, solution and solid-state MAS (19)F NMR spectroscopies, CV and MS studies that the anions [X](-) = [BF(4)](-), [ClO(4)](-) and the anions [Y](-) = [SbF(6)](-), [AsF(6)](-), [PF(6)](-) template molecular squares [Fe(4)(bptz)(4)(CH(3)CN)(8)][X](8) and pentagons [Fe(5)(bptz)(5)(CH(3)CN)(10)][Y](10), respectively. The X-ray structures of [{Fe(4)(bptz)(4)(CH(3)CN)(8)}⊂BF(4)][BF(4)](7) and [{Fe(5)(bptz)(5)(CH(3)CN)(10)}⊂2SbF(6)][SbF(6)](8) revealed that the [BF(4)](-) and [SbF(6)](-) anions occupy the π-acidic cavities, establishing close directional F···C(tetrazine) contacts with the tetrazine rings that are by ~0.4 Å shorter than the sum of the F···C van der Waals radii (ΣR(vdW) F···C = 3.17 Å). The number and strength of F···C(tetrazine) contacts are maximized; the F···C(tetrazine) distances and anion positioning versus the polygon opposing tetrazine rings are in agreement with DFT calculations for C(2)N(4)R(2)···[X](-)···C(2)N(4)R(2) (R = F, CN; [X](-) = [BF(4)](-), [PF(6)](-)). In unprecedented solid-state (19)F MAS NMR studies, the templating anions, engaged in anion-π interactions in the solid state, exhibit downfield chemical shifts Δδ((19)F) ≈ 3.5-4.0 ppm versus peripheral anions. NMR, CV, and MS studies also establish that the Fe(II) metallacycles remain intact in solution. Additionally, interconversion studies between the Fe(II) metallacycles in solution, monitored by (1)H NMR spectroscopy, underscore the remarkable stability of the metallapentacycles [Fe(5)(bptz)(5)(CH(3)CN)(10)][PF(6)](10) ≪ [Fe(5)(bptz)(5)(CH(3)CN)(10)][SbF(6)](10) < [Fe(5)(bptz)(5)(CH(3)CN)(10)][AsF(6)](10) versus [Fe(4)(bptz)(4)(CH(3)CN)(8)][BF(4)](8), given the inherent angle strain in five-membered rings. Finally, the low anion activation energies of encapsulation (ΔG(‡) ≈ 50 kJ/mol), determined from variable-temperature (19)F NMR studies for [Fe(5)(bptz)(5)(CH(3)CN)(10)][PF(6)](10) and [Zn(4)(bptz)(4)(CH(3)CN)(8)][BF(4)](8), confirm anion encapsulation in the π-acidic cavities by anion-π contacts (~20-70 kJ/mol).

Annual AFOSR Chemistry Program Review (19th)

DTIC Science & Technology

1974-01-01

Chem., 42, 161 (1973). "A Rotating Ring Disk Electrode Study of the Adsorption of Lead on Gold in 0.5M Potassium Chloride," V. A. Vicente and S...Gold," D. F. Untereker and S. Bruckenstein, in preparation. "A Rotating Ring-Disk Study of the Adsorption of Thallium on Gold in 0.5H Potassium ... polyacrylic acid, and polydiallyl- phthalate. This paper will only cite the work on the photolysis of polydiallylphthalate. (PDAP). 70 The goal of this

Planetary Rings

NASA Astrophysics Data System (ADS)

Esposito, Larry

2014-03-01

Preface: a personal view of planetary rings; 1. Introduction: the allure of the ringed planets; 2. Studies of planetary rings 1610-2013; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Uranus' rings and moons; 13. Neptune's partial rings; 14. Jupiter's ring-moon system after Galileo and New Horizons; 15. Ring photometry; 16. Dusty rings; 17. Concluding remarks; Afterword; Glossary; References; Index.

Structure-function analysis and genetic interactions of the SmG, SmE, and SmF subunits of the yeast Sm protein ring.

PubMed

Schwer, Beate; Kruchten, Joshua; Shuman, Stewart

2016-09-01

A seven-subunit Sm protein ring forms a core scaffold of the U1, U2, U4, and U5 snRNPs that direct pre-mRNA splicing. Using human snRNP structures to guide mutagenesis in Saccharomyces cerevisiae, we gained new insights into structure-function relationships of the SmG, SmE, and SmF subunits. An alanine scan of 19 conserved amino acids of these three proteins, comprising the Sm RNA binding sites or inter-subunit interfaces, revealed that, with the exception of Arg74 in SmF, none are essential for yeast growth. Yet, for SmG, SmE, and SmF, as for many components of the yeast spliceosome, the effects of perturbing protein-RNA and protein-protein interactions are masked by built-in functional redundancies of the splicing machine. For example, tests for genetic interactions with non-Sm splicing factors showed that many benign mutations of SmG, SmE, and SmF (and of SmB and SmD3) were synthetically lethal with null alleles of U2 snRNP subunits Lea1 and Msl1. Tests of pairwise combinations of SmG, SmE, SmF, SmB, and SmD3 alleles highlighted the inherent redundancies within the Sm ring, whereby simultaneous mutations of the RNA binding sites of any two of the Sm subunits are lethal. Our results suggest that six intact RNA binding sites in the Sm ring suffice for function but five sites may not. © 2016 Schwer et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

The stability of the oscillation motion of charged grains in the Saturnian ring system

NASA Astrophysics Data System (ADS)

Xu, R.-L.; Houpis, L. F.

1985-02-01

A perturbation approach for the gravitoelectrodynamic forces encountered in the corotating plasma environment of Saturn is used to determine the stability of charged grains, given a random initial velocity. Attention is given to the implications of the Northrop and Hill (1982) and Mendis et al. (1982) results for the formation of the Saturnian ring system, and it is suggested that the marginal z stability radius at 1.5245 Saturn radii for Kepler-launched particles is due to an erosion process with ejecta of the order 0.05-0.5 microns, rather than that of the previously suggested plasma. The diffuseness of the Saturnian rings beyond the F ring is also explained in terms of instability, while a new critical radius for r instability is suggestd for the optical depth feature at 1.72 Saturn radii. The F ring is analyzed in detail.

(E)-2-[2-(Penta­fluoro­phen­yl)ethen­yl]-8-quinolyl acetate

PubMed Central

Zhang, Li-Yan; Huo, Yan-Ping

2009-01-01

The title compound, C19H10F5NO2, was synthesized by the 1:1 condensation of 2-methyl-8-hydroxy­quinaldine with penta­fluoro­benzaldehyde. It crystallizes with two almost identical mol­ecules in the asymmetric unit. The penta­fluoro­benzene ring is essentially coplanar with the quinoline ring, forming dihedral angles of 2.49 (17) and 8.72 (16)° in the two mol­ecules. PMID:21578456

Encounter with Saturn: Voyager 1 imaging science results

USGS Publications Warehouse

Smith, B.A.; Soderblom, L.; Beebe, R.; Boyce, J.; Briggs, G.; Bunker, A.; Collins, S.A.; Hansen, C.J.; Johnson, T.V.; Mitchell, J.L.; Terrile, R.J.; Carr, M.; Cook, A.F.; Cuzzi, J.; Pollack, James B.; Danielson, G. Edward; Ingersoll, A.; Davies, M.E.; Hunt, G.E.; Masursky, H.; Shoemaker, E.; Morrison, D.; Owen, Timothy W.; Sagan, C.; Veverka, J.; Strom, R.; Suomi, V.E.

1981-01-01

As Voyager 1 flew through the Saturn system it returned photographs revealing many new and surprising characteristics of this complicated community of bodies. Saturn's atmosphere has numerous, low-contrast, discrete cloud features and a pattern of circulation significantly different from that of Jupiter. Titan is shrouded in a haze layer that varies in thickness and appearance. Among the icy satellites there is considerable variety in density, albedo, and surface morphology and substantial evidence for endogenic surface modification. Trends in density and crater characteristics are quite unlike those of the Galilean satellites. Small inner satellites, three of which were discovered in Voyager images, interact gravitationally with one another and with the ring particles in ways not observed elsewhere in the solar system. Saturn's broad A, B, and C rings contain hundreds of "ringlets," and in the densest portion of the B ring there are numerous nonaxisymmetric features. The narrow F ring has three components which, in at least one instance, are kinked and crisscrossed. Two rings are observed beyond the F ring, and material is seen between the C ring and the planet. Copyright ?? 1981 AAAS.

Universal size properties of a star-ring polymer structure in disordered environments

NASA Astrophysics Data System (ADS)

Haydukivska, K.; Blavatska, V.

2018-03-01

We consider the complex polymer system, consisting of a ring polymer connected to the f1-branched starlike structure, in a good solvent in the presence of structural inhomogeneities. In particular cases f1=1 and f1=2 , such a system restores the synthesized tadpole-shaped polystyrenes [Doi et al., Macromolecules 46, 1075 (2013), 10.1021/ma302511j]. We assume that structural defects are correlated at large distances x according to a power law x-a. Applying the direct polymer renormalization approach, we evaluate the universal size characteristics such as the ratio of the radii of gyration of star-ring and star topologies, and compare the effective sizes of single arms in complex structures and isolated polymers of the same total molecular weight. The nontrivial impact of disorder on these quantities is analyzed.

The 1995 Saturn Ring-Plane Crossings: Ring Thickness and Small Inner Satellites

NASA Astrophysics Data System (ADS)

Poulet, F.; Sicardy, B.

1996-09-01

The May 22() th and August 10() th, 1995, Saturn ring-plane crossings by the Earth were observed from the 2-m and 1-m telescopes at Pic du Midi, the 2.2-m telescope of the University of Hawaii, and with the Adonis adaptive optics camera at the 3.6-m telescope of the European Southern Observatory (ESO). Observations were made with either a 0.9 mu m or 2.2 mu m (short K) methane band filter. The radial brightness profiles of the rings indicate that the outer F ring dominates the apparent edge-on thickness of the system, with a vertically integrated equivalent width of 0.8-1.0 km near a radius of 130,000 km. The photometric behaviors of the A, B, and C rings and of the Cassini Division have been analyzed using a classical radiative transfer code which includes illumination by the Sun and by the planet. The F ring is modelled as a physically thick ribbon (thickness h) composed of large particles embedded in dust. The observed profiles can be explained if the F ring is both optically thick (tau ~ 0.15-0.25), and physically thick (h at least ~ 1.5 km). The large particles dominate the F ring's photometric behavior in backscattered light. Constraints on the particle properties in the other rings have been derived. The dimming of the rings around August 10, 1995 provided ideal conditions to study the small inner satellites. Besides Janus, Epimetheus and Pandora, two unresolved objects were detected in the ESO frames. They have been identified with the objects 1995S5 and 1995S6, detected several hours later by the Hubble Space Telescope (Nicholson et al. 1996, Science 272, 509--515). Combining the ESO and HST data, we derive orbital and photometric parameters for these objects. In particular, we improve the orbital parameters of 1995S5, whose orbital radius is now close to that of the F ring.

Super Star Clusters and H II Regions in Nuclear Rings

NASA Astrophysics Data System (ADS)

Filippenko, Alex

1996-07-01

We propose to obtain WFPC2 optical broad-band {F547M and F814W} and narrow-band Halpha+ionN2 {F658N} images of nuclear starburst rings in four nearby galaxies for which we already have ultraviolet {F220W} FOC data. Nuclear rings {or ``hot- spot'' regions} in barred spirals are some of the nearest and least obscured starburst regions, and HST images of nuclear rings in several galaxies show that the rings contain large populations of super star clusters similar to those recently discovered in other types of starburst systems. These compact clusters, many having luminosities exceeding that of the R136 cluster in 30 Doradus, represent a violent mode of star formation distinct from that seen in ordinary disk ionH2 regions, and the nuclear rings present us with an opportunity to study large numbers of these extreme clusters in relatively unobscured starburst environments. It has been suggested that super star clusters are present-day versions of young globular clusters. To evaluate this hypothesis, it is important to understand the physical properties and stellar contents of the clusters, but previous HST studies of nuclear ring galaxies have only used single-filter observations. Together with our UV data, new WFPC2 images will enable us to determine the H II region and cluster luminosity functions within nuclear rings, measure cluster radii, derive age and mass estimates for the clusters by comparison with evolutionary synthesis models, and study the structure and evolution of nuclear rings.

The vertical structure of the F ring of Saturn from ring-plane crossings

NASA Astrophysics Data System (ADS)

Scharringhausen, Britt R.; Nicholson, Philip D.

2013-11-01

We present a photometric model of the rings of Saturn which includes the main rings and an F ring, inclined to the main rings, with a Gaussian vertical profile of optical depth. This model reproduces the asymmetry in brightness between the east and west ansae of the rings of Saturn that was observed by the Hubble Space Telescope (HST) within a few hours after the Earth ring-plane crossing (RPX) of 10 August 1995. The model shows that during this observation the inclined F ring unevenly blocked the east and west ansae of the main rings. The brightness asymmetry produced by the model is highly sensitive to the vertical thickness and radial optical depth of the F ring. The F-ring model that best matches the observations has a vertical full width at half maximum of 13 ± 7 km and an equivalent depth of 10 ± 4 km. The model also reproduces the shape of the HST profiles of ring brightness vs. distance from Saturn, both before and after the time of ring-plane crossing. Smaller asymmetries observed before the RPX, when the Earth was on the dark side of the rings, cannot be explained by blocking of the main rings by the F ring or vice versa and are probably instead due to the intrinsic longitudinal variation exhibited by the F ring.

Swelling of two-dimensional polymer rings by trapped particles.

PubMed

Haleva, E; Diamant, H

2006-09-01

The mean area of a two-dimensional Gaussian ring of N monomers is known to diverge when the ring is subject to a critical pressure differential, p c ~ N -1. In a recent publication (Eur. Phys. J. E 19, 461 (2006)) we have shown that for an inextensible freely jointed ring this divergence turns into a second-order transition from a crumpled state, where the mean area scales as [A]~N-1, to a smooth state with [A]~N(2). In the current work we extend these two models to the case where the swelling of the ring is caused by trapped ideal-gas particles. The Gaussian model is solved exactly, and the freely jointed one is treated using a Flory argument, mean-field theory, and Monte Carlo simulations. For a fixed number Q of trapped particles the criticality disappears in both models through an unusual mechanism, arising from the absence of an area constraint. In the Gaussian case the ring swells to such a mean area, [A]~ NQ, that the pressure exerted by the particles is at p c for any Q. In the freely jointed model the mean area is such that the particle pressure is always higher than p c, and [A] consequently follows a single scaling law, [A]~N(2) f (Q/N), for any Q. By contrast, when the particles are in contact with a reservoir of fixed chemical potential, the criticality is retained. Thus, the two ensembles are manifestly inequivalent in these systems.

A Photometric Model of the Inclined F Ring of Saturn

NASA Astrophysics Data System (ADS)

Scharringhausen, Britt; Nicholson, P. D.

2007-10-01

Hubble Space Telescope (HST) observations of the August 1995 Saturn ring-plane crossing (RPX) by Earth revealed a surprising east-west asymmetry in ring brightness both before and after the RPX (Nicholson et al. 1996). Previous F-ring models (Poulet et al. 2000) used the overall ring brightness near RPX to probe the photometric thickness of the F ring. In the current work, we exploit the fact that the brightness asymmetry is sensitive to the inclination, node, and physical height of the F ring. We use the inclined F-ring orbit of Bosh et al. (2002), and treat the F ring as a longitudinally symmetric "ribbon" of uniform albedo and phase function with a vertical Gaussian distribution of radial optical depth that has a full height at half maximum of 13±7 km and an equivalent depth (i.e. radially-integrated normal optical depth) of 10±4 km. The model reproduces the observed asymmetry in ring brightness immediately after the RPX, when the Earth is on the sunlit side of the main rings. The F ring obscures the east ansa to a greater extent than the west ansa and the sense of the asymmetry then reverses as the Earth passes through the F-ring plane. Before the RPX, the model does not reproduce the small observed asymmetry in ring brightness, suggesting that the dark-side asymmetry is due to longitudinal variations in the F ring rather than blocking effects. The shapes of model radial profiles of ring brightness are a good match to the HST data both before and after the RPX. This work was supported by NASA.

Planetary rings: Structure and history

NASA Astrophysics Data System (ADS)

Esposito, L.

The composition and structure of planetary rings provide the key evidence to understand their origin and evolution. Before the first space observations, we were able to maintain an idealized view of the rings around Saturn, the only known ring system at that time. Rings were then discovered around Jupiter, Uranus and Neptune. Saturn's F ring was discovered by Pioneer 11. Our ideal view of circular, planar, symmetric and unchanging rings was shattered by observations of inclined, eccentric rings, waves and wavy edges, and numerous processes acting at rates that give timescales much younger than the solar system. Moons within and near the rings sculpt them and are the likely progenitors of future rings. The moonlet lifetimes are much less than Saturn's age. The old idea of ancient rings gave rise to youthful rings, that are recently created by erosion and destruction of small nearby moons. Although this explanation may work well for most rings, Saturn's massive ring system provides a problem. It is extremely improbable that Saturn's rings were recently created by the destruction of a moon as large as Mimas, or even by the breakup of a large comet that passed too close to Saturn. The history of Saturn's rings has been a difficult problem, now made even more challenging by the close-up Cassini measurements. Cassini observations show unexpected ring variability in time and space. Time variations are seen in ring edges, in the thinner D and F rings, and in the neutral oxygen cloud, which outweighs the E ring in the same region around Saturn. The rings are inhomogeneous, with structures on all scales, sharp gradients and edges. Compositional gradients are sharper than expected, but nonetheless cross structural boundaries. This is evidence for ballistic transport that has not gone to completion. The autocovariance maximizes in the middle of the A ring, with smaller structure near the main rings' outer edge. Density wave locations have a fresher ice composition. The processes of collisions, diffusion and transport should have homogenized the rings over the age of the solar system. Instead, these differences persist. The mass density in the Cassini division inferred from density waves is so low, that the material there would be ground to 1 dust in 30,000 years. The observed moons that cause such interesting structure in the rings have short lifetimes against disruption by cometary bombardment and against the angular momentum transfers that push them away from the rings. These rapid processes evident in the Cassini data have been taken as evidence that the rings were recently created, perhaps from a comet that passed too close to Saturn. Instead, an alternative is that primordial material may have been re-used and recycled. In the zone near the Roche limit where rings are found, limited accretion is possible, with the larger bodies able to recapture smaller fragments. The `propeller' structures, the self-gravity wakes, and the size distribution of clumps in Saturn's F ring are all indications of the accretion process. Recycling could extend the ring lifetime almost indefinitely. The variety evident in the latest observations and the low mass density inferred for the largest bodies are both consistent with extensive recycling of ring material as the explanation of the apparent youth of Saturn's rings. Similar processes are likely occurring tin the other ring systems and in the formation of planets around other stars. 2

Moonlets wandering on a leash-ring

NASA Astrophysics Data System (ADS)

Winter, O. C.; Mourão, D. C.; Giuliatti Winter, S. M.; Spahn, F.; da Cruz, C.

2007-09-01

Since the Voyager flybys, embedded moonlets have been proposed to explain some of the surprising structures observed in Saturn's narrow F ring. Experiments conducted with the Cassini spacecraft support this suggestion. Images of the F ring show bright compact spots, and seven occultations of stars by the F ring, monitored by ultraviolet and infrared experiments, revealed nine events of high optical depth. These results point to a large number of such objects, but it is not clear whether they are solid moonlets or rather loose particle aggregates. Subsequent images suggested an irregular motion of these objects so that a determination of their orbits consistent with the F ring failed. Some of these features seem to cross the whole ring. Here we show that these observations are explained by chaos in the F ring driven mainly by the `shepherd' moons Prometheus and Pandora. It is characterized by a rather short Lyapunov time of about a few hundred orbital periods. Despite this chaotic diffusion, more than 93 per cent of the F-ring bodies remain confined within the F ring because of the shepherding, but also because of a weak radial mobility contrasted by an effective longitudinal diffusion. This chaotic stirring of all bodies involved prevents the formation of `propellers' typical of moonlets, but their frequent ring crossings explain the multiple radial `streaks' seen in the F ring. The related `thermal' motion causes more frequent collisions between all bodies which steadily replenish F-ring dust and allow for ongoing fragmentation and re-accretion processes (ring recycling).

Clumps in the F Ring

NASA Image and Video Library

2004-03-12

Scientists have only a rough idea of the lifetime of clumps in Saturn's rings - a mystery that Cassini may help answer. The latest images taken by the Cassini-Huygens spacecraft show clumps seemingly embedded within Saturn's narrow, outermost F ring. The narrow angle camera took the images on Feb. 23, 2004, from a distance of 62.9 million kilometers (39 million miles). The two images taken nearly two hours apart show these clumps as they revolve about the planet. The small dot at center right in the second image is one of Saturn's small moons, Janus, which is 181 kilometers, (112 miles) across. Like all particles in Saturn's ring system, these clump features orbit the planet in the same direction in which the planet rotates. This direction is clockwise as seen from Cassini's southern vantage point below the ring plane. Two clumps in particular, one of them extended, is visible in the upper part of the F ring in the image on the left, and in the lower part of the ring in the image on the right. Other knot-like irregularities in the ring's brightness are visible in the image on the right. The core of the F ring is about 50 kilometers (31miles) wide, and from Cassini's current distance, is not fully visible. The imaging team enhanced the contrast of the images and magnified them to aid visibility of the F ring and the clump features. The camera took the images with the green filter, which is centered at 568 nanometers. The image scale is 377 kilometers (234 miles) per pixel. NASA's two Voyager spacecraft that flew past Saturn in 1980 and 1981 were the first to see these clumps. The Voyager data suggest that the clumps change very little and can be tracked as they orbit for 30 days or more. No clump survived from the time of the first Voyager flyby to the Voyager 2 flyby nine months later. Scientists are not certain of the cause of these features. Among the theories proposed are meteoroid bombardments and inter-particle collisions in the F ring. http://photojournal.jpl.nasa.gov/catalog/PIA05382

The New Horizons and Hubble Space Telescope search for rings, dust, and debris in the Pluto-Charon system

NASA Astrophysics Data System (ADS)

Lauer, Tod R.; Throop, Henry B.; Showalter, Mark R.; Weaver, Harold A.; Stern, S. Alan; Spencer, John R.; Buie, Marc W.; Hamilton, Douglas P.; Porter, Simon B.; Verbiscer, Anne J.; Young, Leslie A.; Olkin, Cathy B.; Ennico, Kimberly; New Horizons Science Team

2018-02-01

We conducted an extensive search for dust or debris rings in the Pluto-Charon system before, during, and after the New Horizons encounter in July 2015. Methodologies included attempting to detect features by back-scattered light during the approach to Pluto (phase angle α ∼ 15°), in situ detection of impacting particles, a search for stellar occultations near the time of closest approach, and by forward-scattered light imaging during departure (α ∼ 165°). An extensive search using the Hubble Space Telescope (HST) prior to the encounter also contributed to the final ring limits. No rings, debris, or dust features were observed, but our new detection limits provide a substantially improved picture of the environment throughout the Pluto-Charon system. Searches for rings in back-scattered light covered the range 35,000-250,000 km from the system barycenter, a zone that starts interior to the orbit of Styx, the innermost minor satellite, and extends out to four times the orbital radius of Hydra, the outermost known satellite. We obtained our firmest limits using data from the New Horizons LORRI camera in the inner half of this region. Our limits on the normal I/F of an unseen ring depends on the radial scale of the rings: 2 ×10-8 (3σ) for 1500 km wide rings, 1 ×10-8 for 6000 km rings, and 7 ×10-9 for 12,000 km rings. Beyond ∼ 100, 000 km from Pluto, HST observations limit normal I/F to ∼ 8 ×10-8 . Searches for dust features from forward-scattered light extended from the surface of Pluto to the Pluto-Charon Hill sphere (rHill = 6.4 ×106 km). No evidence for rings or dust clouds was detected to normal I/F limits of ∼ 8.9 ×10-7 on ∼ 104 km scales. Four stellar occulation observations also probed the space interior to Hydra, but again no dust or debris was detected. The Student Dust Counter detected one particle impact 3.6 × 106 km from Pluto, but this is consistent with the interplanetary space environment established during the cruise of New Horizons. Elsewhere in the solar system, small moons commonly share their orbits with faint dust rings. Our results support recent dynamical studies suggesting that small grains are quickly lost from the Pluto-Charon system due to solar radiation pressure, whereas larger particles are orbitally unstable due to ongoing perturbations by the known moons.

Prometheus and Pandora

NASA Image and Video Library

2004-04-15

Cassini has sighted Prometheus and Pandora, the two F-ring-shepherding moons whose unpredictable orbits both fascinate scientists and wreak havoc on the F ring. Prometheus (102 kilometers, or 63 miles across) is visible left of center in the image, inside the F ring. Pandora (84 kilometers, or 52 miles across) appears above center, outside the ring. The dark shadow cast by the planet stretches more than halfway across the A ring, the outermost main ring. The mottled pattern appearing in the dark regions of the image is 'noise' in the signal recorded by the camera system, which has subsequently been magnified by the image processing. The F ring is a narrow, ribbon-like structure, with a width seen in this geometry equivalent to a few kilometers. The two small, irregularly shaped moons exert a gravitational influence on particles that make up the F ring, confining it and possibly leading to the formation of clumps, strands and other structures observed there. Pandora prevents the F ring from spreading outward and Prometheus prevents it from spreading inward. However, their interaction with the ring is complex and not fully understood. The shepherds are also known to be responsible for many of the observed structures in Saturn's A ring. The moons, which were discovered in images returned by the Voyager 1 spacecraft in 1980, are in chaotic orbits--their orbits can change unpredictably when the moons get very close to each other. This strange behavior was first noticed in ground-based and Hubble Space Telescope observations in 1995, when the rings were seen nearly edge-on from Earth and the usual glare of the rings was reduced, making the satellites more readily visible than usual. The positions of both satellites at that time were different than expected based on Voyager data. One of the goals for the Cassini-Huygens mission is to derive more precise orbits for Prometheus and Pandora. Seeing how their orbits change over the duration of the mission will help to determine their masses, which in turn will help constrain models of their interiors and provide a more complete understanding of their effect on the rings. This narrow angle camera image was snapped through the broadband green spectral filter, centered at 568 nanometers, on March 10, 2004, when the spacecraft was 55.5 million kilometers (34.5 million miles) from the planet. Image scale is approximately 333 kilometers (207 miles) per pixel. Contrast has been greatly enhanced, and the image has been magnified to aid visibility of the moons as well as structure in the rings. http://photojournal.jpl.nasa.gov/catalog/PIA05387

The Day the Earth Smiled

NASA Image and Video Library

2013-11-12

On July 19, 2013, in an event celebrated the world over, NASA's Cassini spacecraft slipped into Saturn's shadow and turned to image the planet, seven of its moons, its inner rings -- and, in the background, our home planet, Earth. With the sun's powerful and potentially damaging rays eclipsed by Saturn itself, Cassini's onboard cameras were able to take advantage of this unique viewing geometry. They acquired a panoramic mosaic of the Saturn system that allows scientists to see details in the rings and throughout the system as they are backlit by the sun. This mosaic is special as it marks the third time our home planet was imaged from the outer solar system; the second time it was imaged by Cassini from Saturn's orbit; and the first time ever that inhabitants of Earth were made aware in advance that their photo would be taken from such a great distance. With both Cassini's wide-angle and narrow-angle cameras aimed at Saturn, Cassini was able to capture 323 images in just over four hours. This final mosaic uses 141 of those wide-angle images. Images taken using the red, green and blue spectral filters of the wide-angle camera were combined and mosaicked together to create this natural-color view. A brightened version with contrast and color enhanced (Figure 1), a version with just the planets annotated (Figure 2), and an annotated version (Figure 3) are shown above. This image spans about 404,880 miles (651,591 kilometers) across. The outermost ring shown here is Saturn's E ring, the core of which is situated about 149,000 miles (240,000 kilometers) from Saturn. The geysers erupting from the south polar terrain of the moon Enceladus supply the fine icy particles that comprise the E ring; diffraction by sunlight gives the ring its blue color. Enceladus (313 miles, or 504 kilometers, across) and the extended plume formed by its jets are visible, embedded in the E ring on the left side of the mosaic. At the 12 o'clock position and a bit inward from the E ring lies the barely discernible ring created by the tiny, Cassini-discovered moon, Pallene (3 miles, or 4 kilometers, across). (For more on structures like Pallene's ring, see PIA08328). The next narrow and easily seen ring inward is the G ring. Interior to the G ring, near the 11 o'clock position, one can barely see the more diffuse ring created by the co-orbital moons, Janus (111 miles, or 179 kilometers, across) and Epimetheus (70 miles, or 113 kilometers, across). Farther inward, we see the very bright F ring closely encircling the main rings of Saturn. Following the outermost E ring counter-clockwise from Enceladus, the moon Tethys (662 miles, or 1,066 kilometers, across) appears as a large yellow orb just outside of the E ring. Tethys is positioned on the illuminated side of Saturn; its icy surface is shining brightly from yellow sunlight reflected by Saturn. Continuing to about the 2 o'clock position is a dark pixel just outside of the G ring; this dark pixel is Saturn's Death Star moon, Mimas (246 miles, or 396 kilometers, across). Mimas appears, upon close inspection, as a very thin crescent because Cassini is looking mostly at its non-illuminated face. The moons Prometheus, Pandora, Janus and Epimetheus are also visible in the mosaic near Saturn's bright narrow F ring. Prometheus (53 miles, or 86 kilometers, across) is visible as a faint black dot just inside the F ring and at the 9 o'clock position. On the opposite side of the rings, just outside the F ring, Pandora (50 miles, or 81 kilometers, across) can be seen as a bright white dot. Pandora and Prometheus are shepherd moons and gravitational interactions between the ring and the moons keep the F ring narrowly confined. At the 11 o'clock position in between the F ring and the G ring, Janus (111 miles, or 179 kilometers, across) appears as a faint black dot. Janus and Prometheus are dark for the same reason Mimas is mostly dark: we are looking at their non-illuminated sides in this mosaic. Midway between the F ring and the G ring, at about the 8 o'clock position, is a single bright pixel, Epimetheus. Looking more closely at Enceladus, Mimas and Tethys, especially in the brightened version of the mosaic, one can see these moons casting shadows through the E ring like a telephone pole might cast a shadow through a fog. In the non-brightened version of the mosaic, one can see bright clumps of ring material orbiting within the Encke gap near the outer edge of the main rings and immediately to the lower left of the globe of Saturn. Also, in the dark B ring within the main rings, at the 9 o'clock position, one can see the faint outlines of two spoke features, first sighted by NASA's Voyager spacecraft in the early 1980s and extensively studied by Cassini. Finally, in the lower right of the mosaic, in between the bright blue E ring and the faint but defined G ring, is the pale blue dot of our planet, Earth. Look closely and you can see the moon protruding from the Earth's lower right. (For a higher resolution view of the Earth and moon taken during this campaign, see PIA14949.) Earth's twin, Venus, appears as a bright white dot in the upper left quadrant of the mosaic, also between the G and E rings. Mars also appears as a faint red dot embedded in the outer edge of the E ring, above and to the left of Venus. For ease of visibility, Earth, Venus, Mars, Enceladus, Epimetheus and Pandora were all brightened by a factor of eight and a half relative to Saturn. Tethys was brightened by a factor of four. In total, 809 background stars are visible and were brightened by a factor ranging from six, for the brightest stars, to 16, for the faintest. The faint outer rings (from the G ring to the E ring) were also brightened relative to the already bright main rings by factors ranging from two to eight, with the lower-phase-angle (and therefore fainter) regions of these rings brightened the most. The brightened version of the mosaic was further brightened and contrast-enhanced all over to accommodate print applications and a wide range of computer-screen viewing conditions. Some ring features -- such as full rings traced out by tiny moons -- do not appear in this version of the mosaic because they require extreme computer enhancement, which would adversely affect the rest of the mosaic. This version was processed for balance and beauty. This view looks toward the unlit side of the rings from about 17 degrees below the ring plane. Cassini was approximately 746,000 miles (1.2 million kilometers) from Saturn when the images in this mosaic were taken. Image scale on Saturn is about 45 miles (72 kilometers) per pixel. This mosaic was made from pictures taken over a span of more than four hours while the planets, moons and stars were all moving relative to Cassini. Thus, due to spacecraft motion, these objects in the locations shown here were not in these specific places over the entire duration of the imaging campaign. Note also that Venus appears far from Earth, as does Mars, because they were on the opposite side of the sun from Earth. http://photojournal.jpl.nasa.gov/catalog/PIA17172

The narrow rings of Jupiter, Saturn and Uranus

NASA Technical Reports Server (NTRS)

Dermott, S. F.; Murray, C. D.; Sinclair, A. T.

1980-01-01

The origin of the newly discovered narrow ring systems around Jupiter, Saturn and Uranus is considered. It is pointed out that both the Uranian and Jovian ring systems have mean orbital radii of 1.8 planetary radii and lie within the Roche zones of their respective planets, and it is suggested that the Jovian ring is the product of the disintegration of a satellite that entered the Roche zone, and that large numbers of small particles are now in horseshoe orbits about the Lagrangian equilibrium points of the remnant chunks. Analysis of the path of a ring particle in a horseshoe orbit is shown to result in ring structures in agreement with those observed for the circular rings of Jupiter and the highly eccentric ring of Uranus. The stability of these ring systems is then considered, and it is suggested that the F ring of Saturn, which lies outside the Roche zone, represents primordial matter not yet accreted by small satellites just inside the Mimas first-order resonances.

Fan in the F Ring

NASA Image and Video Library

2010-07-20

This mosaic of images from NASA Cassini spacecraft depicts fan-like structures in Saturn tenuous F ring. Bright features are also visible near the core of the ring. Such features suggest the existence of additional objects in the F ring.

F Ring Bright Core Clumps

NASA Image and Video Library

2010-07-20

Bright clumps of ring material and a fan-like structure appear near the core of Saturn tenuous F ring in this mosaic of images from NASA Cassini spacecraft. Such features suggest the existence of additional objects in the F ring.

Nonmedially assembled F-actin cables incorporate into the actomyosin ring in fission yeast

PubMed Central

Huang, Junqi; Huang, Yinyi; Yu, Haochen; Subramanian, Dhivya; Padmanabhan, Anup; Thadani, Rahul; Tao, Yaqiong; Tang, Xie; Wedlich-Soldner, Roland

2012-01-01

In many eukaryotes, cytokinesis requires the assembly and constriction of an actomyosin-based contractile ring. Despite the central role of this ring in cytokinesis, the mechanism of F-actin assembly and accumulation in the ring is not fully understood. In this paper, we investigate the mechanism of F-actin assembly during cytokinesis in Schizosaccharomyces pombe using lifeact as a probe to monitor actin dynamics. Previous work has shown that F-actin in the actomyosin ring is assembled de novo at the division site. Surprisingly, we find that a significant fraction of F-actin in the ring was recruited from formin-Cdc12p nucleated long actin cables that were generated at multiple nonmedial locations and incorporated into the ring by a combination of myosin II and myosin V activities. Our results, together with findings in animal cells, suggest that de novo F-actin assembly at the division site and directed transport of F-actin cables assembled elsewhere can contribute to ring assembly. PMID:23185032

25Gb/s 1V-driving CMOS ring modulator with integrated thermal tuning.

PubMed

Li, Guoliang; Zheng, Xuezhe; Yao, Jin; Thacker, Hiren; Shubin, Ivan; Luo, Ying; Raj, Kannan; Cunningham, John E; Krishnamoorthy, Ashok V

2011-10-10

We report a high-speed ring modulator that fits many of the ideal qualities for optical interconnect in future exascale supercomputers. The device was fabricated in a 130 nm SOI CMOS process, with 7.5 μm ring radius. Its high-speed section, employing PN junction that works at carrier-depletion mode, enables 25 Gb/s modulation and an extinction ratio >5 dB with only 1V peak-to-peak driving. Its thermal tuning section allows the device to work in broad wavelength range, with a tuning efficiency of 0.19 nm/mW. Based on microwave characterization and circuit modeling, the modulation energy is estimated ~7 fJ/bit. The whole device fits in a compact 400 μm2 footprint.

Accretion in Saturn's F Ring

NASA Astrophysics Data System (ADS)

Meinke, B. K.; Esposito, L. W.; Stewart, G.

2012-12-01

Saturn's F ring is the solar system's principal natural laboratory for direct observation of accretion and disruption processes. The ring resides in the Roche zone, where tidal disruption competes with self-gravity, which allows us to observe the lifecycle of moonlets. Just as nearby moons create structure at the B ring edge (Esposito et al. 2012) and the Keeler gap (Murray 2007), the F ring "shepherding" moons Prometheus and Pandora stir up ring material and create observably changing structures on timescales of days to decades. In fact, Beurle et al (2010) show that Prometheus makes it possible for "distended, yet gravitationally coherent clumps" to form in the F ring, and Barbara and Esposito (2002) predicted a population of ~1 km bodies in the ring. In addition to the observations over the last three decades, the Cassini Ultraviolet Imaging Spectrograph (UVIS) has detected 27 statistically significant features in 101 occultations by Saturn's F ring since July 2004. Seventeen of those 27 features are associated with clumps of ring material. Two features are opaque in occultation, which makes them candidates for solid objects, which we refer to as Moonlets. The 15 other features partially block stellar signal for 22 m to just over 3.7 km along the radial expanse of the occultation. Upon visual inspection of the occultation profile, these features resemble Icicles, thus we will refer to them as such here. The density enhancements responsible for such signal attenuations are likely due to transient clumping of material, evidence that aggregations of material are ubiquitous in the F ring. Our lengthy observing campaign reveals that Icicles are likely transient clumps, while Moonlets are possible solid objects. Optical depth is an indicator of clumping because more-densely aggregated material blocks more light; therefore, it is natural to imagine moonlets as later evolutionary stage of icicle, when looser clumps of material compact to form a feature that appears opaque in occultation. We suggest that Icicles may evolve into Moonlets, which are an order of magnitude less abundant in UVIS observations. Motivated by the observations and previous models, I develop a more rigorous model of the evolution of aggregates in Saturn's F ring via tidally-modified accretion. I apply the model to the F ring for bodies of constant density undergoing binary collisions. Because the locations of the UVIS-observed clump-associated features are weakly correlated to the location of Prometheus (Esposito et al. 2012) and images show material stirred up after Prometheus passage (Murray et al. 2008), we develop an additional production term describing "enhanced growth" beyond sticking of hard spheres in binary collisions. In the scenario we devise, Prometheus creates high-density regions in which larger bodies efficiently sweep up smaller bodies. Including a term for this growth mechanism in the numerical model results in the modeled size distribution evolving to a state consistent with observations. Together, the observations and model tell a story of how moonlets are made. Prometheus may be the agent responsible for moonlet growth, a complicated and rare process in the F ring. This can explain how accretion gets the upper hand in forming F ring aggregates. Growth and destruction may be cyclical on a longer time scale. This research was supported by the Cassini project.

HUBBLE SEES CHANGES IN GAS SHELL AROUND NOVA CYGNI 1992

NASA Technical Reports Server (NTRS)

2002-01-01

The European Space Agency's ESA Faint Object Camera utilizing the corrective optics provided by NASA's COSTAR (Corrective Optics Space Telescope Axial Replacement), has given astronomers their best look yet at a rapidly ballooning bubble of gas blasted off a star. The shell surrounds Nova Cygni 1992, which erupted on February 19, 1992. A nova is a thermonuclear explosion that occurs on the surface of a white dwarf star in a double star system. The new HST image [right] reveals an elliptical and slightly lumpy ring-like structure. The ring is the edge of a bubble of hot gas blasted into space by the nova. The shell is so thin that the FOC does not resolve its true thickness, even with HST's restored vision. An HST image taken on May 31 1993, [left] 467 days after the explosion, provided the first glimpse of the ring and a mysterious bar-like structure. But the image interpretation was severely hampered by HST's optical aberration, that scattered light from the central star which contaminated the ring's image. A comparison of the pre and post COSTAR/FOC images reveals that the ring has evolved in the seven months that have elapsed between the two observations. The ring has expanded from a diameter of approximately 74 to 96 billion miles. The bar-like structure seen in the earlier HST image has disappear. These changes might confirm theories that the bar was produced by a dense layer of gas thrown off in the orbital plane of the double star system. The gas has subsequently grown more tenuous and so the bar has faded. The ring has also grown noticeably more oblong since the earlier image. This suggests the hot gas is escaping more rapidly above and below the system's orbital plane. As the gas continues escaping the ring should grow increasingly egg-shaped in the coming years. HST's newly improved sensitivity and high resolution provides a unique opportunity to understand the novae by resolving the effects of the explosion long before they can be resolved in ground based telescopes. Nova Cygni is 10,430 light years away (as measured directly from the ring's diameter), and located in the summer constellation Cygnus the Swan. Credit: F. Paresce, R. Jedrzejewski (STScI) NASA/ESA PHOTO RELEASE NO.: STScI-PR94-06

Methyl 6-eth-oxy-3-phenyl-3a,4-dihydro-3H-chromeno[4,3-c]isoxazole-3a-car-boxylate.

PubMed

Suresh, G; Srinivasan, J; Bakthadoss, M; Aravindhan, S

2013-02-01

In the title compound, C(20)H(19)NO(5), the dihedral angle between the mean plane of the pyran ring (which has a half-chair conformation) and the benzene ring of the chromeno ring system is 7.21 (7)°. The dihedral angle between the mean plane of the chromeno ring system and the isoxazole ring is 21.78 (6)°, while the isoxazole ring forms a dihedral angle of 72.60 (8)° with the attached phenyl ring. In the crystal, mol-ecules are linked via pairs of C-H⋯O hydrogen bonds, forming inversion dimers with an R(2) (2)(10) ring motif. These dimers are linked via C-H⋯N hydrogen bonds, forming chains along [001].

Charged dust in Saturn's magnetosphere

NASA Technical Reports Server (NTRS)

Mendis, D. A.; Hill, J. R.; Houpis, H. L. F.

1983-01-01

The overall distribution of fine dust in the Saturnian magnetosphere, its behavior, the cosmogony of the Saturnian ring system, and observations of the magnetosphere and ring system are synthesized and explained using gravito-electrodynamics. Among the phenomena discussed are the formation of waves in the F-ring, the cause of eccentricities of certain isolated ringlets, and the origin and morphology of the broad diffuse E-ring. Magnetogravitational resonance of charged dust with nearby satellites, gyro-orbital resonances, and magnetogravitational capture of exogenic dust by the magnetosphere are used to explain individual observations. The effect of a ring current associated with the charged dust is evaluated. Finally, the cosmogonic implications of the magnetogravitational theory are discussed.

SEVENTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

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

Daugherty, W.

2012-08-30

A series of experiments to monitor the aging performance of Viton® GLT O-rings used in the Model 9975 package has been ongoing since 2004 at the Savannah River National Laboratory. Seventy tests using mock-ups of 9975 Primary Containment Vessels (PCVs) were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially and have been tested periodically to determine if they meet the criterion of leak-tightness defined in ANSI standard N14.5-97. Fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF. High temperature aging continues for 23more » GLT O-ring fixtures at 200 – 270 ºF. Room temperature leak test failures have been experienced in all of the GLT O-ring fixtures aging at 350 ºF and higher temperatures, and in 8 fixtures aging at 300 ºF. The remaining GLT O-ring fixtures aging at 300 ºF have been retired from testing following more than 5 years at temperature without failure. No failures have yet been observed in GLT O-ring fixtures aging at 200 ºF for 54-72 months, which is still bounding to O-ring temperatures during storage in K-Area Complex (KAC). Based on expectations that the fixtures aging at 200 ºF will remain leak-tight for a significant period yet to come, 2 additional fixtures began aging in 2011 at an intermediate temperature of 270 ºF, with hopes that they may reach a failure condition before the 200 ºF fixtures. High temperature aging continues for 6 GLT-S O-ring fixtures at 200 – 300 ºF. Room temperature leak test failures have been experienced in all 8 of the GLT-S O-ring fixtures aging at 350 and 400 ºF. No failures have yet been observed in GLT-S O-ring fixtures aging at 200 - 300 ºF for 30 - 36 months. For O-ring fixtures that have failed the room temperature leak test and been disassembled, the O-rings displayed a compression set ranging from 51 – 96%. This is greater than seen to date for any packages inspected during KAC field surveillance (24% average). For GLT O-rings, separate service life estimates have been made based on the O-ring fixture leak test data and based on compression stress relaxation (CSR) data. These two predictive models show reasonable agreement at higher temperatures (350 – 400 ºF). However, at 300 ºF, the room temperature leak test failures to date experienced longer aging times than predicted by the CSRbased model. This suggests that extrapolations of the CSR model predictions to temperatures below 300 ºF will provide a conservative prediction of service life relative to the leak rate criterion. Leak test failure data at lower temperatures are needed to verify this apparent trend. Insufficient failure data exist currently to perform a similar comparison for GLT-S O-rings. Aging and periodic leak testing will continue for the remaining PCV O-ring fixtures.« less

Lineshape test on overlapped transitions (R9F1, R9F2) of the 2v3 band of 12CH4 by frequency-stabilized cavity ring-down spectroscopy

NASA Astrophysics Data System (ADS)

Yang, L.; Lin, H.; Plimmer, M. D.; Feng, X. J.; Zhang, J. T.

2018-05-01

The performances of a multi-spectral fit for the spectra of pressure-broadened overlapping lines (R9F1, R9F2) of 12CH4 in binary mixtures with N2 were studied by applying different lineshape models, from the simplest Voigt profile (VP) to the Harmann-Tran profile (HTP). Line-mixing was approximated in the first order in the spectral fits. Data were acquired using a high-resolution cavity ring-down spectrometer of minimum detectable absorption coefficient of 2.8 × 10-12 cm-1. The lines were observed with a signal-to-noise ratio of 19 365 for pressures from 5 to 40 kPa. The study reveals that the multi-spectral fits using the HTP and the speed-dependent Nelkin-Ghatak profile (SDNGP) yield the best among all tested. The two models gave the maximum relative residuals of less than 0.065 %. All things considered, the HTP and the SDNGP appear to be the most reliable models for treating the present case of multi-spectral fitting of unresolved dual-component spectra.

Predicted occultations by Uranus - 1981-1984

NASA Technical Reports Server (NTRS)

Klemola, A. R.; Mink, D. J.; Elliot, J. L.

1981-01-01

Predictions are presented for 11 occultations by and appulses to Uranus and its ring system for ten stars from 1981 through 1984. The brightest stars are occulted on April 26, 1981 (BD - 19 deg 4222) and on April 22, 1982 (Hyd - 20 deg 51699). The ring system occults the same star twice during March 1983 (Hyd - 21 deg 64352).

EIGHTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

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

Daugherty, W. L.

2013-09-03

A series of experiments to monitor the aging performance of Viton® GLT O-rings used in the Model 9975 package has been ongoing since 2004 at the Savannah River National Laboratory. Seventy tests using mock-ups of 9975 Primary Containment Vessels (PCVs) were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially and have been tested periodically to determine if they meet the criterion of leak-tightness defined in ANSI standard N14.5-97. Fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF. High temperature aging continues for 23more » GLT O-ring fixtures at 200 – 270 ºF. Room temperature leak test failures have been experienced in all of the GLT O-ring fixtures aging at 350 ºF and higher temperatures, and in 8 fixtures aging at 300 ºF. The remaining GLT O-ring fixtures aging at 300 ºF have been retired from testing following more than 5 years at temperature without failure. No failures have yet been observed in GLT O-ring fixtures aging at 200 ºF for 61 - 85 months, which is still bounding to O-ring temperatures during storage in KArea Complex (KAC). Based on expectations that the fixtures aging at 200 ºF will remain leaktight for a significant period yet to come, 2 additional fixtures began aging in 2011 at an intermediate temperature of 270 ºF, with hopes that they may reach a failure condition before the 200 ºF fixtures. High temperature aging continues for 6 GLT-S O-ring fixtures at 200 – 300 ºF. Room temperature leak test failures have been experienced in all 8 of the GLT-S O-ring fixtures aging at 350 and 400 ºF. No failures have yet been observed in GLT-S O-ring fixtures aging at 200 - 300 ºF for 41 - 45 months. Aging and periodic leak testing will continue for the remaining PCV fixtures.« less

1-[5-(4-Bromo­phen­yl)-3-(4-fluoro­phen­yl)-4,5-dihydro-1H-pyrazol-1-yl]butan-1-one

PubMed Central

Fun, Hoong-Kun; Loh, Wan-Sin; Sapnakumari, M.; Narayana, B.; Sarojini, B. K.

2012-01-01

In the title compound, C19H18BrFN2O, the benzene rings form dihedral angles of 5.38 (7) and 85.48 (7)° with the mean plane of the 4,5-dihydro-1H-pyrazole ring (r.m.s. deviation = 0.0849 Å), which approximates to an envelope conformation with the –CH2– group as the flap. The dihedral angle between the benzene rings is 82.86 (7)°. In the crystal, C—H⋯F and C—H⋯O hydrogen bonds link the mol­ecules to form inversion dimers and together these generate chains along [011]. The crystal packing also features C—H⋯π inter­actions. PMID:22969553

Deceptively Small

NASA Image and Video Library

2015-02-02

Tiny Epimetheus is dwarfed by adjacent slivers of the A and F rings. But is it really? Looks can be deceiving! There is approximately 10 to 20 times more mass in that tiny dot than in the piece of the A ring visible in this image! In total, Saturn's rings have about as much mass as a few times the mass of the moon Mimas. (This mass estimate comes from measuring the waves raised in the rings by moons like Epimetheus.) The rings look physically larger than any moon because the individual ring particles are very small, giving them a large surface area for a given mass. Epimetheus (70 miles or 113 kilometers across), on the other hand, has a small surface area per mass compared to the rings, making it look deceptively small. This view looks toward the sunlit side of the rings from about 19 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Dec. 5, 2014. The view was obtained at a distance of approximately 1.2 million miles (2 million kilometers) from Epimetheus and at a Sun-Epimetheus-spacecraft, or phase, angle of 40 degrees. Image scale is 7 miles (12 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA18302

NINTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

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

Daugherty, W.

2014-08-06

A series of experiments to monitor the aging performance of Viton® GLT O-rings used in the Model 9975 package has been ongoing since 2004 at the Savannah River National Laboratory. One approach has been to periodically evaluate the leak performance of O-rings being aged in mock-up 9975 Primary Containment Vessels (PCVs) at elevated temperatures. Other methods such as compression-stress relaxation (CSR) tests and field surveillance are also on-going to evaluate O-ring behavior. Seventy tests using PCV mock-ups were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially and have been tested periodically to determinemore » if they continue to meet the leak-tightness criterion defined in ANSI standard N14.5-97. Due to material substitution, fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF. High temperature aging continues for 23 GLT O-ring fixtures at 200 – 270 ºF. Room temperature leak test failures have been experienced in all of the GLT O-ring fixtures aging at 350 ºF and higher temperatures, and in 8 fixtures aging at 300 ºF. The earliest 300 °F GLT O-ring fixture failure was observed at 34 months. The remaining GLT O-ring fixtures aging at 300 ºF have been retired from testing following more than 5 years at temperature without failure. No failures have yet been observed in GLT O-ring fixtures aging at 200 ºF for 72 - 96 months, which bounds O-ring temperatures anticipated during storage in K-Area Complex (KAC). Based on expectations that the 200 ºF fixtures will remain leak-tight for a significant period yet to come, 2 additional fixtures began aging in 2011 at 270 ºF, with hopes that they may reach a failure condition before the 200 ºF fixtures, thus providing additional time to failure data. High temperature aging continues for 6 GLT-S O-ring fixtures at 200 – 300 ºF. Room temperature leak test failures have been experienced in all 8 of the GLT-S O-ring fixtures aging at 350 and 400 ºF. No failures have yet been observed in GLT-S O-ring fixtures aging at 200 - 300 ºF for 54 - 57 months. No additional O-ring failures have been observed since the last interim report was issued. Aging and periodic leak testing will continue for the remaining PCV fixtures. Additional irradiation of several fixtures is recommended to maintain a balance between thermal and radiation exposures similar to that experienced in storage, and to show the degree of consistency of radiation response between GLT and GLT-S O-rings.« less

Disruption of N terminus long range non covalent interactions shifted temp.opt 25°C to cold: Evolution of point mutant Bacillus lipase by error prone PCR.

PubMed

Goomber, Shelly; Kumar, Arbind; Kaur, Jagdeep

2016-01-15

Cold adapted enzymes have applications in detergent, textile, food, bioremediation and biotechnology processes. Bacillus lipases are 'generally recognized as safe' (GRAS) and hence are industrially attractive. Bacillus lipase of 1.4 subfamily are of lowest molecular weight and are reversibly unfolded due to absence of disulphide bonds. Therefore these are largely used to study energetic of protein stability that represents unfolding of native protein to fully unfolded state. In present study, metagenomically isolated Bacillus LipJ was laboratory evolved for cold adaptation by error Prone PCR. Library of variants were screened for high relative activity at low temperature of 10°C compared to native protein LipJ. Point mutant sequenced as Phe19→Leu was determined to be active at cold and was selected for extensive biochemical, biophysical characterization. Variant F19L showed its maximum activity at 10°C where parent protein LipJ had 20% relative activity. Psychrophilic nature of F19L was established with about 50% relative active at 5°C where native protein was frozen to act. Variant F19L showed no activity at temperature 40°C and above, establishing its thermolabile nature. Thermostability studies determined mutant to be unstable above 20°C and three fold decrease in its half life at 30°C compared to native protein. Far UV-CD and intrinsic fluorescence study demonstrated unstable tertiary structure of point variant F19L leading to its unfolding at low temperature of 20°C. Cold adaptation of mutant F19L is accompanied with increased specific activity. Mutant was catalytically more efficient with 1.3 fold increase in kcat. Homologue structure modelling predicted disruption of intersecondary hydrophobic core formed by aromatic ring of Phe19 with non polar residues placed at β3, β4, β5, β6, αF. Increased local flexibility of variant F19L explains molecular basis of its psychrophilic nature. Copyright © 2015 Elsevier B.V. All rights reserved.

A Discussion of Arctic Ionograms

DTIC Science & Technology

1980-04-14

elongated ring, the " plasma ring ", which, similar to the spread-F oval, encircled the geo- magnetic pole. Ionograms recorded on the Flying Ionospheric...topside polar F-layer plasma ring existed in the bottomaide as an F-loyer irregularity zone (22). On these flights the latitudinal extent of the F

The Ring Sculptor

NASA Image and Video Library

2006-09-08

Prometheus zooms across the Cassini spacecraft field of view, attended by faint streamers and deep gores in the F ring. This movie sequence of five images shows the F ring shepherd moon shaping the ring inner edge

Decreased cortical activation in response to a motion stimulus in anisometropic amblyopic eyes using functional magnetic resonance imaging.

PubMed

Bonhomme, Gabrielle R; Liu, Grant T; Miki, Atsushi; Francis, Ellie; Dobre, M-C; Modestino, Edward J; Aleman, David O; Haselgrove, John C

2006-12-01

Motion perception abnormalities and extrastriate abnormalities have been suggested in amblyopia. Functional MRI (fMRI) and motion stimuli were used to study whether interocular differences in activation are detectable in motion-sensitive cortical areas in patients with anisometropic amblyopia. We performed fMRI at 1.5 T 4 control subjects (20/20 OU), 1 with monocular suppression (20/25), and 2 with anisometropic amblyopia (20/60, 20/800). Monocular suppression was thought to be form fruste of amblyopia. The experimental stimulus consisted of expanding and contracting concentric rings, whereas the control condition consisted of stationary concentric rings. Activation was determined by contrasting the 2 conditions for each eye. Significant fMRI activation and comparable right and left eye activation was found in V3a and V5 in all control subjects (Average z-values in L vs R contrast 0.42, 0.43) and in the subject with monocular suppression (z = 0.19). The anisometropes exhibited decreased extrastriate activation in their amblyopic eyes compared with the fellow eyes (zs = 2.12, 2.76). Our data suggest motion-sensitive cortical structures may be less active when anisometropic amblyopic eyes are stimulated with moving rings. These results support the hypothesis that extrastriate cortex is affected in anisometropic amblyopia. Although suggestive of a magnocellular defect, the exact mechanism is unclear.

A new F-actin structure in fungi: actin ring formation around the cell nucleus of Cryptococcus neoformans.

PubMed

Kopecká, Marie; Kawamoto, Susumu; Yamaguchi, Masashi

2013-04-01

The F-actin cytoskeleton of Cryptococcus neoformans is known to comprise actin cables, cortical patches and cytokinetic ring. Here, we describe a new F-actin structure in fungi, a perinuclear F-actin collar ring around the cell nucleus, by fluorescent microscopic imaging of rhodamine phalloidin-stained F-actin. Perinuclear F-actin rings form in Cryptococcus neoformans treated with the microtubule inhibitor Nocodazole or with the drug solvent dimethyl sulfoxide (DMSO) or grown in yeast extract peptone dextrose (YEPD) medium, but they are absent in cells treated with Latrunculin A. Perinuclear F-actin rings may function as 'funicular cabin' for the cell nucleus, and actin cables as intracellular 'funicular' suspending nucleus in the central position in the cell and moving nucleus along the polarity axis along actin cables.

Chair interconversion and reactivity of mannuronic acid esters.

PubMed

Rönnols, Jerk; Walvoort, Marthe T C; van der Marel, Gijsbert A; Codée, Jeroen D C; Widmalm, Göran

2013-12-14

Mannopyranosyluronic acids display a very unusual conformation behavior in that they often prefer to adopt a (1)C4 chair conformation. They are endowed with a strikingly high reactivity when used in a glycosylation reaction as a glycosyl donor. To investigate the unusual conformational behavior a series of mannuronic acid ester derivatives, comprising anomeric triflate species and O-methyl glycosides, was examined by dynamic NMR experiments, through lineshape analysis of (1)H and (19)F NMR spectra at various temperatures from -80 °C to 0 °C. Exchange rates between (4)C1 and (1)C4 chair conformations were found to depend on the electronic properties and the size of the C2 substituent (F, N3 or OBn) and the aglycon, with higher exchange rates for the glycosyl triflates and smaller C2 substituents. Low temperature (19)F exchange spectroscopy experiments showed that the covalently bound anomeric triflates did not exchange with free triflate species present in the reaction mixture. To relate the conformational behavior of the intermediate triflates to their reactivity in a glycosylation reaction, their relative reactivity was determined via competition reactions monitored by (1)H NMR spectroscopy at low temperature. The 2-O-benzyl ether compound was found to be most reactive whereas the 2-fluoro compound - the most flexible of the studied compounds - was least reactive. Whereas the ring-flip of the mannuronic acids is important for the enhanced reactivity of the donors, the rate of the ring-flip has little influence on the relative reactivity.

FY2017 status report: Model 9975 O-ring fixture long-term leak performance

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

Daugherty, W. L.

A series of experiments to monitor the aging performance of Viton® GLT and GLT-S O-rings used in the Model 9975 shipping package has been ongoing since 2004 at the Savannah River National Laboratory. One approach has been to periodically evaluate the leak performance of O-rings being aged in mock-up 9975 Primary Containment Vessels (PCVs) at elevated temperature. Other methods such as compression-stress relaxation (CSR) tests and field surveillance are also on-going to evaluate O-ring behavior. Seventy tests using PCV mock-ups with GLT O-rings were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially andmore » have been tested periodically to determine if they continue to meet the leak-tightness criterion defined in ANSI standard N14.5-97. Due to material substitution, a smaller test matrix with fourteen additional tests was initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF. Leak test failures have been experienced in all of the GLT O-ring fixtures aging at 350 ºF and higher temperatures, and in 8 fixtures aging at 300 ºF. The 300 °F GLT O-ring fixtures failed after 2.8 to 5.7 years at temperature. The remaining GLT O-ring fixtures aging at 300 ºF were retired from testing following more than 5 years at temperature without failure. No failures have yet been observed in GLT O-ring fixtures aging at 200 ºF for 9 to 10.5 years, or in GLT O-ring fixtures aging at 270 ºF for 5.7 years. These aging temperatures bound O-ring temperatures anticipated during normal storage in K-Area Complex (KAC). Leak test failures have been experienced in all of the GLT-S O-ring fixtures aging at 300 ºF and above. No failures have yet been observed in GLT-S O-ring fixtures aging at 200 and 250 ºF for 6.9 to 7.5 years. Data from the O-ring fixtures are generally consistent with results from compression stress relaxation testing, and provide confidence in the predictive models based on those results. However, uncertainty still exists in extrapolating these elevated temperature results to the lower temperatures of interest for normal storage in KAC. Measurement of compression set in O-rings removed from failed fixtures, compared to that from KAC surveillance O-rings, indicates margin remains for O-rings still in service. Aging and periodic leak testing will continue for the remaining PCV fixtures.« less

Improved piston ring materials for 650 deg C service

NASA Technical Reports Server (NTRS)

Bjorndahl, W. D.

1986-01-01

A program to develop piston ring material systems which will operate at 650C was performed. In this program, two candidate high temperature piston ring substrate materials, Carpenter 709-2 and 440B, were hot formed into the piston ring shape and subsequently evaluated. In a parallel development effort ceramic and metallic piston ring coating materials were applied to cast iron rings by various processing techniques and then subjected to thermal shock and wear evaluation. Finally, promising candidate coatings were applied to the most thermally stable hot formed substrate. The results of evaluation tests of the hot formed substrate show that Carpenter 709-2 has greater thermal stability than 440B. Of the candidate coatings, plasma transferred arc (PTA) applied tungsten carbide and molybdenum based systems exhibit the greatest resistance to thermal shock. For the ceramic based systems, thermal shock resistance was improved by bond coat grading. Wear testing was conducted to 650C (1202F). For ceramic systems, the alumina/titania/zirconia/yttria composition showed highest wear resistance. For the PTA applied systems, the tungsten carbide based system showed highest wear resistance.

SIXTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

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

Daugherty, W.

2011-08-31

A series of experiments to monitor the aging performance of Viton{reg_sign} GLT O-rings used in the Model 9975 package has been ongoing for seven years at the Savannah River National Laboratory. Seventy tests using mock-ups of 9975 Primary Containment Vessels (PCVs) were assembled and heated to temperatures ranging from 200 to 450 F. They were leak-tested initially and have been tested periodically to determine if they meet the criterion of leak-tightness defined in ANSI standard N14.5-97. Fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 F. High temperature aging continues formore » 33 GLT O-ring fixtures at 200-300 F. Room temperature leak test failures have been experienced in all of the GLT O-ring fixtures aging at 350 F and higher temperatures, and in 7 fixtures aging at 300 F. No failures have yet been observed in GLT O-ring fixtures aging at 200 F for 41-60 months, which is still bounding to O-ring temperatures during storage in K-Area Complex (KAC). Based on expectations that the fixtures aging at 200 F will remain leak-tight for a significant period yet to come, 2 additional fixtures began aging within the past year at an intermediate temperature of 270 F, with hopes that they may leak before the 200 F fixtures. High temperature aging continues for 6 GLT-S O-ring fixtures at 200-300 F. Room temperature leak test failures have been experienced in all 8 of the GLT-S O-ring fixtures aging at 350 and 400 F. No failures have yet been observed in GLT-S O-ring fixtures aging at 200-300 F for up to 26 months. For O-ring fixtures that have failed the room temperature leak test and been disassembled, the Orings displayed a compression set ranging from 51-96%. This is greater than seen to date for packages inspected during KAC field surveillance (24% average). For GLT O-rings, separate service life estimates have been made based on the O-ring fixture leak test data and based on compression stress relaxation (CSR) data. These two predictive models show reasonable agreement at higher temperatures (350-400 F). However, at 300 F, the room temperature leak test failures to date experienced longer aging times than predicted by the CSR-based model. This suggests that extrapolations of the CSR model predictions to temperatures below 300 F will provide a conservative prediction of service life relative to the leak rate criterion. Leak test failure data at lower temperatures are needed to verify this apparent trend. Insufficient failure data exist currently to perform a similar comparison for GLT-S O-rings. Aging and periodic leak testing will continue for the remaining fixtures.« less

Fiber ring laser sensor based on Fabry-Perot cavity interferometer for temperature sensing

NASA Astrophysics Data System (ADS)

Zou, Hui; Ma, Lei; Xiong, Hui; Zhang, Yunshan; Li, Yong Tao

2018-01-01

A ring laser temperature sensor based on a novel reflective fiber Fabry-Perot (F-P) interferometer air cavity is proposed and experimentally demonstrated. The reflective F-P air cavity, which consists of a segment of glass capillary inserted between two single-mode fibers, is utilized as a sensing element as well as as a filter in the fiber ring cavity. As temperature increases, the reflection spectra of the F-P sensor move towards the longer wavelength, and then cause lasing wavelength shifts. By monitoring the variation of lasing wavelength, we obtain a temperature sensor system with a high temperature sensitivity of 0.249 nm °C-1, a narrow 3 dB bandwidth of 0.1514 nm, and a high signal-to-noise ratio of 52 dB. Moreover, it is convenient to fabricate the sensor head, and the stability is very good, giving it a wide range of applications.

Automatic flatness detection system for micro part

NASA Astrophysics Data System (ADS)

Luo, Yi; Wang, Xiaodong; Shan, Zhendong; Li, Kehong

2016-01-01

An automatic flatness detection system for micro rings is developed. It is made up of machine vision module, ring supporting module and control system. An industry CCD camera with the resolution of 1628×1236 pixel, a telecentric with magnification of two, and light sources are used to collect the vision information. A rotary stage with a polished silicon wafer is used to support the ring. The silicon wafer provides a mirror image and doubles the gap caused by unevenness of the ring. The control system comprise an industry computer and software written in LabVIEW Get Kernel and Convolute Function are selected to reduce noise and distortion, Laplacian Operator is used to sharp the image, and IMAQ Threshold function is used to separate the target object from the background. Based on this software, system repeating precision is 2.19 μm, less than one pixel. The designed detection system can easily identify the ring warpage larger than 5 μm, and if the warpage is less than 25 μm, it can be used in ring assembly and satisfied the final positionary and perpendicularity error requirement of the component.

The c15 ring of the Spirulina platensis F-ATP synthase: F1/F0 symmetry mismatch is not obligatory

PubMed Central

Pogoryelov, Denys; Yu, Jinshu; Meier, Thomas; Vonck, Janet; Dimroth, Peter; Muller, Daniel J

2005-01-01

The oligomeric c ring of the F-ATP synthase from the alkaliphilic cyanobacterium Spirulina platensis was isolated and characterized. Mass spectroscopy analysis indicated a mass of 8,210 Da, reflecting that of a c monomer. The mass increased by 206 Da after treatment with the c-subunit-specific inhibitor dicyclohexylcarbodiimide (DCCD), which indicated modification of the ion-binding carboxylate by DCCD. Atomic force microscopy topographs of c rings from S. platensis showed 15 symmetrically assembled subunits. The c15-mer reported here is the largest c ring that is isolated and does not show the classical c-ring mismatch to the three-fold symmetry of the F1 domain. PMID:16170308

Crystal structure of 3-amino-1-(4-meth-oxy-phen-yl)-1H-benzo[f]chromene-2-carbo-nitrile.

PubMed

Mohamed, Shaaban K; Horton, Peter N; Akkurt, Mehmet; Younes, Sabry H H; Albayati, Mustafa R

2015-07-01

In the title compound, C21H16N2O2, the meth-oxy-benzene ring is almost perpendicular to the mean plane of the naphthalene ring system, making a dihedral angle of 83.62 (5)°. The 4H-pyran ring fused with the naphthalene ring system is almost planar [maximum deviation = 0.033 (1) Å]. In the crystal, mol-ecules are linked into inversion dimers by pairs of N-H⋯N hydrogen bonds. N-H⋯O hydrogen bonds connect the dimers, forming a helical supra-molecular chain along the a-axis direction. The crystal packing also features C-H⋯π inter-actions.

A Farewell to Saturn

NASA Image and Video Library

2017-11-21

After more than 13 years at Saturn, and with its fate sealed, NASA's Cassini spacecraft bid farewell to the Saturnian system by firing the shutters of its wide-angle camera and capturing this last, full mosaic of Saturn and its rings two days before the spacecraft's dramatic plunge into the planet's atmosphere. During the observation, a total of 80 wide-angle images were acquired in just over two hours. This view is constructed from 42 of those wide-angle shots, taken using the red, green and blue spectral filters, combined and mosaicked together to create a natural-color view. Six of Saturn's moons -- Enceladus, Epimetheus, Janus, Mimas, Pandora and Prometheus -- make a faint appearance in this image. (Numerous stars are also visible in the background.) A second version of the mosaic is provided in which the planet and its rings have been brightened, with the fainter regions brightened by a greater amount. (The moons and stars have also been brightened by a factor of 15 in this version.) The ice-covered moon Enceladus -- home to a global subsurface ocean that erupts into space -- can be seen at the 1 o'clock position. Directly below Enceladus, just outside the F ring (the thin, farthest ring from the planet seen in this image) lies the small moon Epimetheus. Following the F ring clock-wise from Epimetheus, the next moon seen is Janus. At about the 4:30 position and outward from the F ring is Mimas. Inward of Mimas and still at about the 4:30 position is the F-ring-disrupting moon, Pandora. Moving around to the 10 o'clock position, just inside of the F ring, is the moon Prometheus. This view looks toward the sunlit side of the rings from about 15 degrees above the ring plane. Cassini was approximately 698,000 miles (1.1 million kilometers) from Saturn, on its final approach to the planet, when the images in this mosaic were taken. Image scale on Saturn is about 42 miles (67 kilometers) per pixel. The image scale on the moons varies from 37 to 50 miles (59 to 80 kilometers) pixel. The phase angle (the Sun-planet-spacecraft angle) is 138 degrees. The Cassini spacecraft ended its mission on Sept. 15, 2017. https://photojournal.jpl.nasa.gov/catalog/PIA17218

Dynamics of Clumps in Saturn's F Ring

NASA Astrophysics Data System (ADS)

Showalter, M. R.

1997-07-01

An exhaustive analysis of the Voyager image data sets reveals the F Ring to be the most dynamic ring in the solar system. Principal properties are as follows. (1) At any given time, the ring holds 2--3 extremely bright clumps (each several times brighter than the local average for the ring) and perhaps 20--40 identifiable smaller clumps. In practice, the closer one looks at the rings, the finer detail one finds. (2) No major clumps persist for the nine months between the Voyager encounters, but most survive for the ~ 6 weeks they can be detected during a single encounter. (3) A few major clumps are seen to appear or disappear very quickly, on time scales as brief as days. One clump appears to spread longitudinally after it first appears, but other clumps stay roughly fixed in longitudinal extend. The processes behind clump formation and destruction are unknown. (4) Clumps propagate at different mean motions; there is no evidence for a discrete set of rates that might correspond to the individual ``strands'' described in some models. Motions range from 581.81(deg) /day to 582.41(deg) /day, implying that the F Ring's clumps span a semimajor axis range of ~ 80 km. (5) Some sections of the ring show a distinct 3.2(deg) periodicity in clump spacing, as expected from the gravitational perturbations by Prometheus. Others do not. (6) In the Voyager 2 images, a single prominent clump seems to eject smaller clumps behind it on time scales of ~ 2 weeks. However, nothing analogous is observed in Voyager 1 data.

Determining the relative strengths of aromatic and aliphatic C-H⋅⋅⋅X hydrogen bonds in imidazolium ionic liquids through measurement of H/D isotope effects on 19 F nuclear shielding.

PubMed

Bottini, Gualberto; Moyna, Guillermo

2018-02-01

The relative strengths of aromatic and aliphatic C-H⋅⋅⋅X hydrogen bonds in imidazolium ionic liquids were investigated through measurement of H/D isotope effects on the 19 F nuclear shielding of deuterated isotopologues of 1-n-butyl-3-methylimidazolium hexafluorophosphate and tetrafluoroborate ([C 4 mim]PF 6 and [C 4 mim]BF 4 ). Δ 19 F(H,D) values ranging from 9.7 to 49.7 ppb were observed for [C 4 mim]PF 6 isotopologues, while for the [C 4 mim]BF 4 series these went from 26.2 to 83.8 ppb. Our findings indicate that the interactions between the fluorinated anions and protons on the C-1' and C-1″ position of the N-alkyl sidechains are comparable to, and in some cases stronger than, those involving protons on the aromatic ring, underscoring the role that these weak interionic forces have on the local ordering of imidazolium salts in the liquid state. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Development of a circular shape Si-PM-based detector ring for breast-dedicated PET system

NASA Astrophysics Data System (ADS)

Nakanishi, Kouhei; Yamamoto, Seiichi; Watabe, Hiroshi; Abe, Shinji; Fujita, Naotoshi; Kato, Katsuhiko

2018-02-01

In clinical situations, various breast-dedicated positron emission tomography (PET) systems have been used. However, clinical breast-dedicated PET systems have polygonal detector ring. Polygonal detector ring sometimes causes image artifact, so complicated reconstruction algorithm is needed to reduce artifact. Consequently, we developed a circular detector ring for breast-dedicated PET to obtain images without artifact using a simple reconstruction algorithm. We used Lu1.9Gd0.1SiO5 (LGSO) scintillator block which was made of 1.5 x 1.9 x 15 mm pixels that were arranged in an 8 x 24 matrix. As photodetectors, we used silicon photomultiplier (Si-PM) arrays whose channel size was 3 x 3 mm. A detector unit was composed of four scintillator blocks, 16 Si-PM arrays and a light guide. The developed detector unit had angled configuration since the light guide was bending. A detector unit had three gaps with an angle of 5.625° between scintillator blocks. With these configurations, we could arrange 64 scintillator blocks in nearly circular shape (regular 64-sided polygon) using 16 detector units. The use of the smaller number of detector units could reduce the size of the front-end electronics circuits. The inner diameter of the developed detector ring was 260 mm. This size was similar to those of brain PET systems, so our breast-dedicated PET detector ring can measure not only breast but also brain. Measured radial, tangential and axial spatial resolution of the detector ring reconstructed by the filtered back-projection (FBP) algorithm were 2.1 mm FWHM, 2.0 mm FWHM and 1.7 mm FWHM at center of field of view (FOV), respectively. The sensitivity was 2.0% at center of the axial FOV. With the developed detector ring, we could obtain high resolution image of the breast phantom and the brain phantom. We conclude that our developed Si-PM-based detector ring is promising for a high resolution breast-dedicated PET system that can also be used for brain PET system.

A Dark Bend

NASA Image and Video Library

2016-09-05

Saturn's rings appear to bend as they pass behind the planet's darkened limb due to refraction by Saturn's upper atmosphere. The effect is the same as that seen in an earlier Cassini view (see PIA20491), except this view looks toward the unlit face of the rings, while the earlier image viewed the rings' sunlit side. The difference in illumination brings out some noticeable differences. The A ring is much darker here, on the rings' unlit face, since its larger particles primarily reflect light back toward the sun (and away from Cassini's cameras in this view). The narrow F ring (at bottom), which was faint in the earlier image, appears brighter than all of the other rings here, thanks to the microscopic dust that is prevalent within that ring. Small dust tends to scatter light forward (meaning close to its original direction of travel), making it appear bright when backlit. (A similar effect has plagued many a driver with a dusty windshield when driving toward the sun.) This view looks toward the unilluminated side of the rings from about 19 degrees below the ring plane. The image was taken in red light with the Cassini spacecraft narrow-angle camera on July 24, 2016. The view was acquired at a distance of approximately 527,000 miles (848,000 kilometers) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 169 degrees. Image scale is 3 miles (5 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA20497

Crystal structure of (3S*,4R*)-4-fluoro-3-(4-meth-oxy-phen-yl)-1-oxo-2-phenyl-1,2,3,4-tetra-hydro-iso-quinoline-4-carb-oxy-lic acid.

PubMed

Lehmann, Anna; Lechner, Lisa; Radacki, Krzysztof; Braunschweig, Holger; Holzgrabe, Ulrike

2017-06-01

The title compound, C 23 H 18 FNO 4 , crystallized as a racemate. It exhibits a cis conformation with respect to the F atom and the methine H atom. The piperidine ring has a screw-boat conformation. The meth-oxy-phenyl ring and the phenyl ring are inclined to the mean plane of the iso-quinoline ring system by 89.85 (4) and 46.62 (5)°, respectively, and by 78.15 (5)° to one another. In the crystal, mol-ecules are linked by an O-H⋯O hydrogen bond forming chains propagating along the a -axis direction. The chains are linked by C-H⋯F hydrogen bonds, forming layers lying parallel to the ab plane.

Involvement of an Actomyosin Contractile Ring in Saccharomyces cerevisiae Cytokinesis

PubMed Central

Bi, Erfei; Maddox, Paul; Lew, Daniel J.; Salmon, E.D.; McMillan, John N.; Yeh, Elaine; Pringle, John R.

1998-01-01

In Saccharomyces cerevisiae, the mother cell and bud are connected by a narrow neck. The mechanism by which this neck is closed during cytokinesis has been unclear. Here we report on the role of a contractile actomyosin ring in this process. Myo1p (the only type II myosin in S. cerevisiae) forms a ring at the presumptive bud site shortly before bud emergence. Myo1p ring formation depends on the septins but not on F-actin, and preexisting Myo1p rings are stable when F-actin is depolymerized. The Myo1p ring remains in the mother–bud neck until the end of anaphase, when a ring of F-actin forms in association with it. The actomyosin ring then contracts to a point and disappears. In the absence of F-actin, the Myo1p ring does not contract. After ring contraction, cortical actin patches congregate at the mother–bud neck, and septum formation and cell separation rapidly ensue. Strains deleted for MYO1 are viable; they fail to form the actin ring but show apparently normal congregation of actin patches at the neck. Some myo1Δ strains divide nearly as efficiently as wild type; other myo1Δ strains divide less efficiently, but it is unclear whether the primary defect is in cytokinesis, septum formation, or cell separation. Even cells lacking F-actin can divide, although in this case division is considerably delayed. Thus, the contractile actomyosin ring is not essential for cytokinesis in S. cerevisiae. In its absence, cytokinesis can still be completed by a process (possibly localized cell–wall synthesis leading to septum formation) that appears to require septin function and to be facilitated by F-actin. PMID:9732290

Saturn's F-Ring

NASA Technical Reports Server (NTRS)

2000-01-01

This narrow-angle camera image of Saturn's F Ring was taken through the Clear filter while at a distance of 6.9 million km from Saturn on 8 November 1980. The brightness variations of this tightly-constrained ring shown here indicate that the ring is less uniform in makeup than the larger rings. JPL managed the Voyager Project for NASA's Office of Space Science

Charged Particle In-Situ Measurements in the Inner Saturnian Magnetosphere during the "grand Finale" of Cassini in 2016/2017

NASA Astrophysics Data System (ADS)

Krupp, N.; Roussos, E.; Mitchell, D. G.; Kollmann, P.; Paranicas, C.; Krimigis, S. M.; Hedman, M. M.; Dougherty, M. K.

2017-12-01

After 13 years in orbit around Saturn Cassini came to an end on 15 September 2017. The last phase of the mission was called the "Grand Finale" and consisted of high latitude orbits crossing the F-Ring 22 times between Nov 2016 and April 2017 followed by the so called proximal orbits passing the ring plane inside the D-ring. The roughly 7-day long F-ring orbits with periapsis at nearly the same local time allowed to study temporal variations of the particle distributions in the inner part of Saturn's magnetosphere while during the proximal orbits Cassini measured for the first time the charged particle environment in-situ inside the D-ring up to 2500 km above the 1-bar cloud level of the planet. In this presentation first results of the Low Energy Magnetospheric Measurement System LEMMS, part of the Magnetosphere Imaging Instrument MIMI during the "Grand Finale" will be summarized in detail, including the discovery of MeV particles close to Saturn, higher intensities of charged particles when Cassini was magnetically connected to the D-Ring, sharp dropouts at the inner edge of the D-ring as well as unexpected features and asymmetries in the particle measurements related to newly discovered ring arcs in the inner magnetosphere.

Regulation of Split Linear Systems Over Rings: Coefficient-Assignment and Observers,

DTIC Science & Technology

1980-02-22

we give for the first time , a method to obtain an observer for a finite -free strongly observable The K-linear map irQ is defined as system 5" ( F. G...NAME a ADORESS~if dif!ttrent from Controlling Office) IS1 SECURITY CLASS . (of this report) SIS.. DE CL ASSI ’I CATION/ODOWNGRADING SCHEDULE 16...Entered) IEEE rRANSACTIONS ON AUTOMATIC CONTROL . VOL. Ac-27 . No. 1. FEaRUAay 1982 Regutlation of Split Linear Systems Over Rings: Coefficient

Development of an Inflatable Head/Neck Restraint System for Ejection Seats (Update)

DTIC Science & Technology

1978-12-19

REPORT NO. NADC-78213-60 DEVELOPMENT OF AN INFLATABLE HEAD /NECK RESTRAINT SYSTEM FOR EJECTION SEATS (UPD ATE) Thomas J. Zenobi Aircraft and Crew...olde if necsesey anid dentlif hr bl0ck ma11,0s.) t Inflatable neck collar Inflatable neck ring Neck injury Head rotation ý2 .AeSSRACT (Continus on...toenes side It nec~essary mod identl)_* by block naob..) F1 A ring-shaped inflatable head /neck restraint system for ejection seats is be- ing developed at

Field-Aligned Currents in Saturn's Magnetosphere: Observations From the F-Ring Orbits

NASA Astrophysics Data System (ADS)

Hunt, G. J.; Provan, G.; Bunce, E. J.; Cowley, S. W. H.; Dougherty, M. K.; Southwood, D. J.

2018-05-01

We investigate the azimuthal magnetic field signatures associated with high-latitude field-aligned currents observed during Cassini's F-ring orbits (October 2016-April 2017). The overall ionospheric meridional current profiles in the northern and southern hemispheres, that is, the regions poleward and equatorward of the field-aligned currents, differ most from the 2008 observations. We discuss these differences in terms of the seasonal change between data sets and local time (LT) differences, as the 2008 data cover the nightside while the F-ring data cover the post-dawn and dusk sectors in the northern and southern hemispheres, respectively. The F-ring field-aligned currents typically have a similar four current sheet structure to those in 2008. We investigate the properties of the current sheets and show that the field-aligned currents in a hemisphere are modulated by that hemisphere's "planetary period oscillation" (PPO) systems. We separate the PPO-independent and PPO-related currents in both hemispheres using their opposite symmetry. The average PPO-independent currents peak at 1.5 MA/rad just equatorward of the open closed field line boundary, similar to the 2008 observations. However, the PPO-related currents in both hemispheres are reduced by 50% to 0.4 MA/rad. This may be evidence of reduced PPO amplitudes, similar to the previously observed weaker equatorial oscillations at similar dayside LTs. We do not detect the PPO current systems' interhemispheric component, likely a result of the weaker PPO-related currents and their closure within the magnetosphere. We also do not detect previously proposed lower latitude discrete field-aligned currents that act to "turn off" the PPOs.

Evidence of Accretion in Saturn's F Ring (Invited)

NASA Astrophysics Data System (ADS)

Agnor, C. B.; Buerle, K.; Murray, C. D.; Evans, M. W.; Cooper, N. J.; Williams, G. W.

2010-12-01

Lying slightly outside the classical Roche radius and being strongly perturbed by the adjacent moons Prometheus and Pandora, Saturn's F ring represents a unique astrophysical laboratory for examining the processes of mass accretion and moonlet formation. Recent images from the Cassini spacecraft reveal optically thick clumps, capable of casting shadows, and associated structures in regions of the F ring following close passage by Prometheus. Here we examine the accretion environment of the F ring and Prometheus' role in moonlet formation and evolution. Using the observed structures adjacent to these clumps and dynamical arguments we estimate the masses of these clumps and find them comparable to that of ~10-20-km contiguous moonlets. Further, we show that Prometheus' perturbations on the F ring create regions of enhanced density and low relative velocity that may accelerate the accretion of clumps and moonlets.

Cassini UVIS solar occultations by Saturn's F ring and the detection of collision-produced micron-sized dust

NASA Astrophysics Data System (ADS)

Becker, Tracy M.; Colwell, Joshua E.; Esposito, Larry W.; Attree, Nicholas O.; Murray, Carl D.

2018-05-01

We present an analysis of eleven solar occultations by Saturn's F ring observed by the Ultraviolet Imaging Spectrograph (UVIS) on the Cassini spacecraft. In four of the solar occultations we detect an unambiguous signal from diffracted sunlight that adds to the direct solar signal just before or after the occultations occur. The strongest detection was a 10% increase over the direct signal that was enabled by the accidental misalignment of the instrument's pointing. We compare the UVIS data with images of the F ring obtained by the Cassini Imaging Science Subsystem (ISS) and find that in each instance of an unambiguous diffraction signature in the UVIS data, the ISS data shows that there was a recent disturbance in that region of the F ring. Similarly, the ISS images show a quiescent region of the F ring for all solar occultations in which no diffraction signature was detected. We therefore conclude that collisions in the F ring produce a population of small ring particles that can produce a detectable diffraction signal immediately interior or exterior to the F ring. The clearest example of this connection comes from the strong detection of diffracted light in the 2007 solar occultation, when the portion of the F ring that occulted the Sun had suffered a large collisional event, likely with S/2004 S 6, several months prior. This collision was observed in a series of ISS images (Murray et al., 2008). Our spectral analysis of the data shows no significant spectral features in the F ring, indicating that the particles must be at least 0.2 μm in radius. We apply a forward model of the solar occultations, accounting for the effects of diffracted light and the attenuated direct solar signal, to model the observed solar occultation light curves. These models constrain the optical depth, radial width, and particle size distribution of the F ring. We find that when the diffraction signature is present, we can best reproduce the occultation data using a particle population with an average effective particle size of less than 300 μm, while occultations without clear diffraction signals are best modeled using a population with an effective particle size larger than 400 μm.

One last look from the dark side: Cassini's final views of Saturn's rings from with the planet's shadow

NASA Astrophysics Data System (ADS)

Hedman, Matthew M.; Burns, Joseph A.; Nicholson, Philip D.; Tiscareno, Matthew S.; Evans, Michael W.; Baker, Emily

2017-10-01

Around the start of Cassini's Grand Finale, the spacecraft passed a dozen times through Saturn's shadow, enabling its cameras and spectrometers to observe the ring system at extremely high phase angles. These opportunities yielded the best combination of signal-to-noise and resolution for many parts of Saturn's fainter dusty rings, and allowed the main rings to be viewed from previously inaccessible lighting geometries. We will highlight some of the surprising features found in the data obtained by Cassini's Imaging Science Subsystem (ISS) and Visual and Infrared Mapping Spectrometer (VIMS) during these time periods, and discuss what they might be able to tell us about the structure and dynamics of Saturn's various ring systems. For example, ISS captured global views of the entire ring system that reveal previously unseen structures in dust-filled regions like the D ring and the zone between Saturn's F and G rings, as well as novel fine-scale structures in the core of the E ring near Enceladus' orbit. These structures provide new insights into the forces that sculpt these tenuous rings. ISS and VIMS also detected an unexpected brightening and highly unusual spectra of the main rings at extremely high phase angles. These data may provide novel information about the distribution of small grains and particles in these denser rings.

HST Multicolor (255-1042 nm) Photometry of Saturn's Main Rings. 1; Radial Profiles, Phase and Opening Angle Variations, and Regional Spectra

NASA Technical Reports Server (NTRS)

Cuzzi, Jeffrey N.; French, Richard G.; Dones, Luke; DeVincenzi, Donald (Technical Monitor)

2001-01-01

The main rings of Saturn were observed with the Planetary Camera of the WFPC2 instrument on the Hubble Space Telescope (HST) from September 1996 to August 2000 as the'ring opening angle to Earth and Sun increased from 4 deg to 24 deg, with a spread of phase angles between 0.3 deg and 6 deg at each opening angle. The rings were routinely observed in the five HST wideband UBVRI filters (F336W, F439W, F555W, F675W, and F814W) and occasionally in the F255W, F785LP, and F1042M filters. The emphasis in this series of papers will be on radial color (implying compositional) variations. In this first paper we describe the analysis technique and calibration procedure, note revisions in a previously published Voyager ring color data analysis, and present new results based on over 100 HST images. In the 300-600 nm spectral range where the rings are red, the 555nm/336nm ratio increases by about 14% as the phase angle increases from 0.3 deg to 6 deg. This effect, never reported previously for the rings, is significantly larger than the phase reddening which characterizes other icy objects, primarily because of the redness of the rings. However, there is no discernible tendency for color to vary with ring opening angle at a given phase angle, and there is no phase variation of color where the spectrum is flat. We infer from this combination of facts that multiple intraparticle scattering, either in a regolith or between facets of an unusually rough surface, is important in these geometries, but that multiple interparticle scattering in a vertically extended layer is not. Voyager color ratios at a phase angle of 14 deg are compatible with this trend, but calibration uncertainties prevent their use in quantitative modeling. Overall ring-average spectra are compatible with those of earlier work within calibration uncertainties, but ring spectra vary noticeably with region. We refine and subdivide the regions previously defined by others. The variation seen between radial profiles of ratios between different wavelength suggests the presence of multiple compositional components with different radial distributions. We present new radial profiles of far UV color ratio (F336W/F255W) showing, substantial global variations having a different radial structure than seen between 555 and 336nm. We also find evidence for absorption in the 850nm spectral range (a feature previously only weakly indicated in ring-averaged spectra) primarily through its radial variation; it is located primarily in the C ring, where the particles are known to have lower albedo, and is consistent with "interplanetary pollution" of the rings.

Unfocused F Ring

NASA Image and Video Library

2007-04-02

The F ring dissolves into a fuzzy stream of particles -- rather different from its usual appearance of a narrow, bright core flanked by dimmer ringlets. Also notable here is the bright clump of material that flanks the ring core

The Odd Trio

NASA Image and Video Library

2014-09-22

The Cassini spacecraft captures a rare family photo of three of Saturn's moons that couldn't be more different from each other! As the largest of the three, Tethys (image center) is round and has a variety of terrains across its surface. Meanwhile, Hyperion (to the upper-left of Tethys) is the "wild one" with a chaotic spin and Prometheus (lower-left) is a tiny moon that busies itself sculpting the F ring. To learn more about the surface of Tethys (660 miles, or 1,062 kilometers across), see PIA17164 More on the chaotic spin of Hyperion (168 miles, or 270 kilometers across) can be found at PIA07683 And discover more about the role of Prometheus (53 miles, or 86 kilometers across) in shaping the F ring in PIA12786. This view looks toward the sunlit side of the rings from about 1 degree above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 14, 2014. The view was acquired at a distance of approximately 1.2 million miles (1.9 million kilometers) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 22 degrees. Image scale is 7 miles (11 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA18283

The Binary Fission Model for the Formation of the Pluto system

NASA Astrophysics Data System (ADS)

Prentice, Andrew

2016-10-01

The ratio F of the mass of Pluto (P) to Charon (C), viz. F ≈ 8:1, is the largest ratio of any planet-satellite pair in the solar system. Another measure of the PC binary is its normalized angular momentum density J (see McKinnon 1989). Analysis of astrometric data (Brozovic et al 2015) acquired before the New Horizons (NH) arrival at Pluto and new measurements made by NH (Stern et al 2015) show that J = 0.39. Yet these F & J values are ones expected if the PC binary had formed by the rotational fission of a single liquid mass (Darwin 1902; Lyttleton 1953). At first glance, therefore, the fission model seems to be a viable model for the formation of the Pluto system. In fact, Prentice (1993 Aust J Astron 5 111) had used this model to successfully predict the existence of several moons orbiting beyond Charon, before their discovery in 2005-2012. The main problem with the fission model is that the observed mean density of Charon, namely 1.70 g/cm3, greatly exceeds that of water ice. Charon thus could not have once been a globe of pure water. Here I review the fission model within the framework of the modern Laplacian theory of solar system origin (Prentice 1978 Moon Planets 19 341; 2006 PASA 23 1) and the NH results. I assume that Pluto and Charon were initially a single object (proto-Pluto [p-P]) which had condensed within the same gas ring shed by the proto-solar cloud at orbital distance ~43 AU, where the Kuiper belt was born. The temperature of this gas ring is 26 K and the mean orbit pressure is 1.3 × 10-9 bar. After the gas ring is shed, chemical condensation takes place. The bulk chemical composition of the condensate is anhydrous rock (mass fraction 0.5255), graphite (0.0163), water ice (0.1858), CO2 ice (0.2211) and methane ice (0.0513). Next I assume that melting of the ices in p-P takes place through the decay of short-lived radioactive nuclides, thus causing internal segregation of the rock & graphite. Settling of heavy grains to the centre lowers the MOI of p-P, so triggering rotational disruption. Pluto's moons would then form from liquid water and liquid CO2, as well as entrained rock-graphite grains. Charon's mean density implies that the rock-graphite mass fraction of the fissioned mass was ˜0.41.

Magnetic anisotropy of the antiferromagnetic ring [Cr8F8Piv16].

PubMed

van Slageren, Joris; Sessoli, Roberta; Gatteschi, Dante; Smith, Andrew A; Helliwell, Madeleine; Winpenny, Richard E P; Cornia, Andrea; Barra, Anne-Laure; Jansen, Aloysius G M; Rentschler, Eva; Timco, Grigore A

2002-01-04

A new tetragonal (P42(1)2) crystalline form of [Cr8F8Piv16] (HPiv = pivalic acid, trimethyl acetic acid) is reported. The ring-shaped molecules, which are aligned in a parallel fashion in the unit cell, form almost perfectly planar, regular octagons. The interaction between the CrIII ions is antiferromagnetic (J = 12 cm(-1)) which results in a S = 0 spin ground state. The low-lying spin excited states were investigated by cantilever torque magnetometry (CTM) and high-frequency EPR (HFEPR). The compound shows hard-axis anisotropy. The axial zero-field splitting (ZFS) parameters of the first two spin excited states (S = 1 and S = 2, respectively) are D1 = 1.59(3) cm(-1) or 1.63 cm(-1) (from CTM and HFEPR, respectively) and D2 = 0.37 cm(-1) (from HFEPR). The dipolar contributions to the ZFS of the S = 1 and S = 2 spin states were calculated with the point dipolar approximation. These contributions proved to be less than the combined single-ion contributions. Angular overlap model calculations that used parameters obtained from the electronic absorption spectrum, showed that the unique axis of the single-ion ZFS is at an angle of 19.3(1) degrees with respect to the ring axis. The excellent agreement between the experimental and the theoretical results show the validity of the used methods for the analysis of the magnetic anisotropy in antiferromagnetic CrIII rings.

Hardy Objects in Saturn F Ring

NASA Image and Video Library

2017-02-24

As NASA's Cassini spacecraft continues its weekly ring-grazing orbits, diving just past the outside of Saturn F ring, it is tracking several small, persistent objects there. These images show two such objects that Cassini originally detected in spring 2016, as the spacecraft transitioned from more equatorial orbits to orbits at increasingly high inclination about the planet's equator. Imaging team members studying these objects gave them the informal designations F16QA (right image) and F16QB (left image). The researchers have observed that objects such as these occasionally crash through the F ring's bright core, producing spectacular collisional structures.While these objects may be mostly loose agglomerations of tiny ring particles, scientists suspect that small, fairly solid bodies lurk within each object, given that they have survived several collisions with the ring since their discovery. The faint retinue of dust around them is likely the result of the most recent collision each underwent before these images were obtained. The researchers think these objects originally form as loose clumps in the F ring core as a result of perturbations triggered by Saturn's moon Prometheus. . If they survive subsequent encounters with Prometheus, their orbits can evolve, eventually leading to core-crossing clumps that produce spectacular features, even though they collide with the ring at low speeds. The images were obtained using the Cassini spacecraft narrow-angle camera on Feb. 5, 2017, at a distance of 610,000 miles (982,000 kilometers, left image) and 556,000 miles (894,000 kilometers, right image) from the F ring. Image scale is about 4 miles (6 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA21432

Evaluation of a LiF:Mg,Ti thermoluminescent ring dosimeter according to the IEC 62387:2012 Standards

NASA Astrophysics Data System (ADS)

Oliveira, Edyelle L. B.; de Barros, Vinícius S. M.; Asfora, Viviane K.; Khoury, Helen J.

2018-03-01

This work shows results of type testing of a ring radiation dosimeter system under IEC 62387:2012. The personal dosimeter investigated in this work consists of a commercial one element plastic ring which contains an LiF:Mg,Ti thermoluminescent pellet. By applying requirements for statistical fluctuations and linearity, a minimum measurable dose in Hp(0.07) was established. Energy and angular dependence aided in determining energy correction factors and fading requirements were used to select the most appropriate preheat scheme. Type testing of passive radiation monitors was performed in the Radiation Metrology Laboratory (LMRI-DEN/UFPE) of the Federal University of Pernambuco and is a major step in Brazil for the independent evaluation of these dosimeters, currently not available in the country.

The Use of Statistical Measures to Validate System Dynamics Models

DTIC Science & Technology

1992-03-01

C15: (T) [W15] +[FORMMSE]CI4 D15: (T) [W12] +B15-$B$19 E15: (T) +C15-$C$19 F15: (T) (W30] +D15*E15 A16: (T) [W15] +[FORMMSE]AI5 B16 : (T) (W331...FORMMSE]BI5 C16: (T) [W151 +[FORMMSE]C15 D16: (T) [W121 + B16 -$B$19 E16: (T) +C16-$C$19 46 F16: (T) [W30] +D16*El6 A17: (T) [W15] +[FORMMSE]A16 F17: (T...W30] @SUM(F7. .F16) A19: (T) CW151 "Mean= B19: (T) [W331 @AVG(B7. . Bl6 ) C19: (T) [W153 QAVG(C7. .C16) E19: (T) 11r= F19: (T) [W30] ((1/A17)*(F17))/((B20

The Christiansen Effect in Saturn's narrow dusty rings and the spectral identification of clumps in the F ring

USGS Publications Warehouse

Hedman, M.M.; Nicholson, P.D.; Showalter, M.R.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Baines, K.; Sotin, Christophe

2011-01-01

Stellar occultations by Saturn's rings observed with the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft reveal that dusty features such as the F ring and the ringlets in the Encke and the Laplace Gaps have distinctive infrared transmission spectra. These spectra show a narrow optical depth minimum at wavelengths around 2.87??m. This minimum is likely due to the Christiansen Effect, a reduction in the extinction of small particles when their (complex) refractive index is close to that of the surrounding medium. Simple Mie-scattering models demonstrate that the strength of this opacity dip is sensitive to the size distribution of particles between 1 and 100??m across. Furthermore, the spatial resolution of the occultation data is sufficient to reveal variations in the transmission spectra within and among these rings. In both the Encke Gap ringlets and F ring, the opacity dip weakens with increasing local optical depth, which is consistent with the larger particles being concentrated near the cores of these rings. The Encke Gap ringlets also show systematically weaker opacity dips than the F ring and Laplace Gap ringlet, implying that the former has a smaller fraction of grains less than ~30??m across. However, the strength of the opacity dip varies most dramatically within the F ring; certain compact regions of enhanced optical depth lack an opacity dip and therefore appear to have a greatly reduced fraction of grains in the few-micron size range. Such spectrally-identifiable structures probably represent a subset of the compact optically-thick clumps observed by other Cassini instruments. These variations in the ring's particle size distribution can provide new insights into the processes of grain aggregation, disruption and transport within dusty rings. For example, the unusual spectral properties of the F-ring clumps could perhaps be ascribed to small grains adhering onto the surface of larger particles in regions of anomalously low velocity dispersion. ?? 2011 Elsevier Inc.

Moons Around Saturn

NASA Technical Reports Server (NTRS)

1996-01-01

This series of 10 Hubble Space Telescope images captures several small moons orbiting Saturn. Hubble snapped the five pairs of images while the Earth was just above the ring plane and the Sun below it. The telescope captured a pair of images every 97 minutes as it circled the Earth. Moving out from Saturn, the visible rings are: the broad C Ring, the Cassini Division, and the narrow F Ring.

The first pair of images shows the large, bright moon Dione, near the middle of the frames. Two smaller moons, Pandora (the brighter one closer to Saturn) and Prometheus, appear as if they're touching the F Ring. In the second frame, Mimas emerges from Saturn's shadow and appears to be chasing Prometheus.

In the second image pair, Mimas has moved towards the tip of the F Ring. Rhea, another bright moon, has just emerged from behind Saturn. Prometheus, the closest moon to Saturn, has rounded the F Ring's tip and is approaching the planet. The slightly larger moon Epimetheus has appeared.

The third image pair shows Epimetheus, as a tiny dot just beyond the tip of the F Ring. Prometheus is in the lower right corner. An elongated clump or arc of debris in the F ring is seen as a slight brightening on the far side of this thin ring.

In the fourth image pair, Epimetheus, in the lower right corner, streaks towards Saturn. The long ring arc can be seen in both frames.

The fifth image pair again captures Mimas, beyond the tip of the F Ring. The same ring arc is still visible.

In addition to the satellites, a pair of stars can be seen passing behind the rings, appearing to move towards the lower left due to Saturn's motion across the sky.

The images were taken Nov. 21, 1995 with Wide Field Planetary Camera-2.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Study of idempotents in cyclic group rings over F{sub 2}

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

Ong, Kai Lin, E-mail: i.am.kailin@hotmail.com; Ang, Miin Huey, E-mail: mathamh@usm.my

The existence of an idempotent generator for group codes or group ring codes in F{sub q}G plays a very important role in determining the minimal distance of the respective code. Some necessary and sufficient conditions for a group ring element to be an idempotent in F{sub 2}C{sub n} are investigated in this paper. The main result in this paper is the affirmation of the existence of finitely many basis idempotents which gives a full identification of all idempotents in every binary cyclic group ring F{sub 2}C{sub n}. All the basis idempotents in F{sub 2}C{sub n} are able to be foundmore » by partitioning the largest idempotent’s support.« less

A C2HC zinc finger is essential for the RING-E2 interaction of the ubiquitin ligase RNF125

PubMed Central

Bijlmakers, Marie-José; Teixeira, João M. C.; Boer, Roeland; Mayzel, Maxim; Puig-Sàrries, Pilar; Karlsson, Göran; Coll, Miquel; Pons, Miquel; Crosas, Bernat

2016-01-01

The activity of RING ubiquitin ligases (E3s) depends on an interaction between the RING domain and ubiquitin conjugating enzymes (E2), but posttranslational events or additional structural elements, yet largely undefined, are frequently required to enhance or regulate activity. Here, we show for the ubiquitin ligase RNF125 that, in addition to the RING domain, a C2HC Zn finger (ZnF) is crucial for activity, and a short linker sequence (Li2120-128) enhances activity. The contribution of these regions was first shown with truncated proteins, and the essential role of the ZnF was confirmed with mutations at the Zn chelating Cys residues. Using NMR, we established that the C2HC ZnF/Li2120-128 region is crucial for binding of the RING domain to the E2 UbcH5a. The partial X-ray structure of RNF125 revealed the presence of extensive intramolecular interactions between the RING and C2HC ZnF. A mutation at one of the contact residues in the C2HC ZnF, a highly conserved M112, resulted in the loss of ubiquitin ligase activity. Thus, we identified the structural basis for an essential role of the C2HC ZnF and conclude that this domain stabilizes the RING domain, and is therefore required for binding of RNF125 to an E2. PMID:27411375

Nuclear Rings in the IR: Hidden Super Star Clusters

NASA Astrophysics Data System (ADS)

Maoz, Dan

1997-07-01

We propose NICMOS broad-band {F160W, F187W} and Paschen Alpha {F187N} imaging of nuclear starburst rings in two nearby galaxies. We already have UV {F220W} FOC data, and are scheduled to obtain WFPC2 images in U, V, I, and Halpha+[NII] of these rings. The rings contain large populations of super star clusters similar to those recently discovered in other types of starburst systems. Nuclear rings contain large numbers of these clusters in relatively unobscured starburst environments. Measurement of the age, size, and stellar contents of the clusters can test the hypothesis that super star clusters are young globular clusters. Together with our UV and optical data, NICMOS images will provide the SED of numerous super star clusters over a decade in wavelength. Our already-approved observations will allow us to estimate, by comparison with evolutionary synthesis models, the masses and ages of the clusters. The proposed IR data will be sensitive to the number of supergiants {1.6 micron} and O-stars {Paschen Alpha} in each of the clusters. The observations will provide an independent determination of the reddening, mass, and age of each cluster. We expect to see in the IR numerous clusters that are obscured in the UV and optical. These clusters may be the younger ones, which are still embedded in their molecular clouds. By measuring the mass, age, and size of a large number of clusters, we can actually obtain an evolutionary picture of these objects at different stages in their lives.

Two F Ring Views

NASA Technical Reports Server (NTRS)

2005-01-01

These views, taken two hours apart, demonstrate the dramatic variability in the structure of Saturn's intriguing F ring.

In the image at the left, ringlets in the F ring and Encke Gap display distinctive kinks, and there is a bright patch of material on the F ring's inner edge. Saturn's moon Janus (181 kilometers, or 113 miles across) is shown here, partly illuminated by reflected light from the planet.

At the right, Prometheus (102 kilometers, or 63 miles across) orbits ahead of the radial striations in the F ring, called 'drapes' by scientists. The drapes appear to be caused by successive passes of Prometheus as it reaches the greatest distance (apoapse) in its orbit of Saturn. Also in this image, the outermost ringlet visible in the Encke Gap displays distinctive bright patches.

These views were obtained from about three degrees below the ring plane.

The images were taken in visible light with the Cassini spacecraft narrow-angle camera on June 29, 2005, when Cassini was about 1.5 million kilometers (900,000 miles) from Saturn. The image scale is about 9 kilometers (6 miles) per pixel.

Dissecting the function of Cullin-RING ubiquitin ligase complex genes in planarian regeneration.

PubMed

Strand, Nicholas S; Allen, John M; Ghulam, Mahjoobah; Taylor, Matthew R; Munday, Roma K; Carrillo, Melissa; Movsesyan, Artem; Zayas, Ricardo M

2018-01-15

The ubiquitin system plays a role in nearly every aspect of eukaryotic cell biology. The enzymes responsible for transferring ubiquitin onto specific substrates are the E3 ubiquitin ligases, a large and diverse family of proteins, for which biological roles and target substrates remain largely undefined. Studies using model organisms indicate that ubiquitin signaling mediates key steps in developmental processes and tissue regeneration. Here, we used the freshwater planarian, Schmidtea mediterranea, to investigate the role of Cullin-RING ubiquitin ligase (CRL) complexes in stem cell regulation during regeneration. We identified six S. mediterranea cullin genes, and used RNAi to uncover roles for homologs of Cullin-1, -3 and -4 in planarian regeneration. The cullin-1 RNAi phenotype included defects in blastema formation, organ regeneration, lesions, and lysis. To further investigate the function of cullin-1-mediated cellular processes in planarians, we examined genes encoding the adaptor protein Skp1 and F-box substrate-recognition proteins that are predicted to partner with Cullin-1. RNAi against skp1 resulted in phenotypes similar to cullin-1 RNAi, and an RNAi screen of the F-box genes identified 19 genes that recapitulated aspects of cullin-1 RNAi, including ones that in mammals are involved in stem cell regulation and cancer biology. Our data provides evidence that CRLs play discrete roles in regenerative processes and provide a platform to investigate how CRLs regulate stem cells in vivo. Copyright © 2017 Elsevier Inc. All rights reserved.

Formation and characterization of a multicomponent equilibrium system derived from cis- and trans-1-aminomethylcyclohexane-1,2-diol.

PubMed

Hetényi, Anasztázia; Szakonyi, Zsolt; Klika, Karel D; Pihlaja, Kalevi; Fülöp, Ferenc

2003-03-21

Both cis and trans isomers of amino diols 3-6 were prepared stereoselectively. In the reactions between 3-6 and phenyl isothiocyanate, the ring closure proceeded regioselectively and resulted only in spiro derivatives of 2-phenyliminooxazolidines 9, 10, 13, and 14. The reaction of cis- (or trans-)1-aminomethylcyclohexane-1,2-diol 4 (or 6) with 1 equiv of an aromatic aldehyde 15a-g in EtOH at room temperature resulted in a complex, multicomponent equilibrium mixture of 16a-g and 18a-g (or 17a-g and 19a-g), in each case consisting of a five-component, ring-chain tautomeric system 16A-E (or 17A-E), involving the Schiff base, two epimeric spirooxazolidines, two epimeric condensed 1,3-oxazines, and some of the four tricyclic compounds 18A-D (or 19A-D). The five-component, ring-chain equilibria were found to be adequately described by the Hammett-Brown linear free energy equation.

Faint F Ring and Prometheus

NASA Image and Video Library

2016-11-21

Surface features are visible on Saturn's moon Prometheus in this view from NASA's Cassini spacecraft. Most of Cassini's images of Prometheus are too distant to resolve individual craters, making views like this a rare treat. Saturn's narrow F ring, which makes a diagonal line beginning at top center, appears bright and bold in some Cassini views, but not here. Since the sun is nearly behind Cassini in this image, most of the light hitting the F ring is being scattered away from the camera, making it appear dim. Light-scattering behavior like this is typical of rings comprised of small particles, such as the F ring. This view looks toward the unilluminated side of the rings from about 14 degrees below the ring plane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 24, 2016. The view was acquired at a distance of approximately 226,000 miles (364,000 kilometers) from Prometheus and at a sun-Prometheus-spacecraft, or phase, angle of 51 degrees. Image scale is 1.2 miles (2 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA20508

Elucidation of the biosynthesis of the methane catalyst coenzyme F430

PubMed Central

Moore, Simon J.; Sowa, Sven T.; Schuchardt, Christopher; Deery, Evelyne; Lawrence, Andrew D.; Ramos, José Vazquez; Billig, Susan; Birkemeyer, Claudia; Chivers, Peter T.; Howard, Mark J.; Rigby, Stephen E. J.; Layer, Gunhild; Warren, Martin J.

2017-01-01

Summary Methane biogenesis in methanogens is mediated by methyl-coenzyme M reductase, an enzyme that is also responsible for the utilisation of methane through anaerobic methane oxidation. The enzyme employs an ancillary factor called coenzyme F430, a nickel-containing modified tetrapyrrole that promotes catalysis through a novel methyl radical/Ni(II)-thiolate intermediate. However, the biosynthesis of coenzyme F430 from the common primogenitor uroporphyrinoge III, incorporating 11 steric centres into the macrocycle, has remained poorly understood although the pathway must involve chelation, amidation, macrocyclic ring reduction, lactamisation and carbocyclic ring formation. We have now identified the proteins that catalyse coenzyme F430 biosynthesis from sirohydrochlorin, termed CfbA-E, and shown their activity. The research completes our understanding of how nature is able to construct its repertoire of tetrapyrrole-based life pigments, permitting the development of recombinant systems to utilise these metalloprosthetic groups more widely. PMID:28225763

F Ring Core Stability: Corotation Resonance Plus Antiresonance

NASA Technical Reports Server (NTRS)

Cuzzi, Jeffrey N.; Marouf, Essam; French, Richard; Jacobson, Robert

2014-01-01

The decades-or-longer stability of the narrow F Ring core in a sea of orbital chaos appears to be due to an unusual combination of traditional corotation resonance and a novel kind of "antiresonance". At a series of specific locations in the F Ring region, apse precession between synodic encounters with Prometheus allows semimajor axis perturbations to promptly cancel before significant orbital period changes can occur. This cancellation fails for particles that encounter Prometheus when it is near its apoapse, especially during periods of antialignment of its apse with that of the F Ring. At these times, the strength of the semimajor axis perturbation is large (tens of km) and highly nonsinusoidal in encounter longitude, making it impossible to cancel promptly on a subsequent encounter and leading to chaotic orbital diffusion. Only particles that consistently encounter Prometheus away from its apoapse can use antiresonance to maintain stable orbits, implying that the true mean motion nF of the stable core must be defined by a corotational resonance of the form nF = nP(-kappa)P/m, where (nP, kappaP) are Prometheus' mean motion and epicycle frequency. To test this hypothesis we used the fact that Cassini RSS occultations only sporadically detect a "massive" F Ring core, composed of several-cm-and-larger particles. We regressed the inertial longitudes of 24 Cassini RSS (and VGR) detections and 43 nondetections to a common epoch, using a comb of candidate nP, and then folded them modulo the anticipated m-number of the corotational resonance (Prometheus m = 110 outer CER), to see if clustering appears. We find the "true F Ring core" is actually arranged in a series of short longitudinal arcs separated by nearly empty longitudes, orbiting at a well determined semimajor axis of 140222.4 km (from 2005-2012 at least). Small particles seen by imaging and stellar occultations spread quickly in azimuth and obscure this clumpy structure. Small chaotic variations in the mean motion and/or apse longitude of Prometheus quickly become manifest in the F Ring core, and we suggest that the core must adapt to these changes for the F Ring to maintain stability over timescales of decades and longer

Placental IGF-1 and IGFBP-3 expression correlate with umbilical cord blood PAH and PBDE levels from prenatal exposure to electronic waste.

PubMed

Xu, Xijin; Yekeen, Taofeek Akangbe; Xiao, Qiongna; Wang, Yuangping; Lu, Fangfang; Huo, Xia

2013-11-01

Electronic waste recycling produces Polycyclic Aromatic Hydrocarbons (PAHs) and Polybrominated Diphenyl Ethers (PBDEs) which may affect fetal growth and development by altering the insulin-like-growth factor (IGF) system. Questionnaires were administered to pregnant women (Guiyu, an e-waste site, n = 101; control, n = 53), and umbilical cord blood (UCB) and placentas were collected upon delivery. PBDEs and PAHs in UCB and placental IGF-1 and IGFBP-3 mRNA levels were analyzed using GC-MS and real-time PCR, respectively. Infant birth length and Apgar scores were lower in Guiyu. All PAHs (except Fl, Chr, IP, BbF and BP), total 16-PAHs, total/individual PBDEs, placental IGF-1 (median 0.23 vs 0.19; P < 0.05) and IGFBP-3 (median 1.91 vs 0.68; P < 0.001) levels were significantly higher in Guiyu. Spearman correlation showed that BDE-154, BDE-209 and ∑5ring-PAHs positively correlate with IGF-1 while PBDEs, 4 rings and total PAHs correlate with IGFBP-3 expression. Increased placental IGF-1 level might indirectly affect fetal growth and development. Copyright © 2013. Published by Elsevier Ltd.

Three closely related 4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridines: synthesis, molecular conformations and hydrogen bonding in zero, one and two dimensions.

PubMed

Sagar, Belakavadi K; Harsha, Kachigere B; Yathirajan, Hemmige S; Rangappa, Kanchugarakoppal S; Rathore, Ravindranath S; Glidewell, Christopher

2017-03-01

In each of 1-(4-fluorophenyl)-5-methylsulfonyl-3-[4-(trifluoromethyl)phenyl]-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine, C 21 H 19 F 4 N 3 O 2 S, (I), 1-(4-chlorophenyl)-5-methylsulfonyl-3-[4-(trifluoromethyl)phenyl]-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine, C 21 H 19 ClF 3 N 3 O 2 S, (II), and 1-(3-methylphenyl)-5-methylsulfonyl-3-[4-(trifluoromethyl)phenyl]-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine, C 22 H 22 F 3 N 3 O 2 S, (III), the reduced pyridine ring adopts a half-chair conformation with the methylsulfonyl substituent occupying an equatorial site. Although compounds (I) and (II) are not isostructural, having the space groups Pbca and P2 1 2 1 2 1 , respectively, their molecular conformations are very similar, but the conformation of compound (III) differs from those of (I) and (II) in the relative orientation of the N-benzyl and methylsulfonyl substituents. In compounds (II) and (III), but not in (I), the trifluoromethyl groups are disordered over two sets of atomic sites. Molecules of (I) are linked into centrosymmetric dimers by C-H...π(arene) hydrogen bonds, molecules of (II) are linked by two C-H...O hydrogen bonds to form ribbons of R 3 3 (18) rings, which are themselves further linked by a C-Cl...π(arene) interaction, and a combination of C-H...O and C-H...π(arene) hydrogen bonds links the molecules of (III) into sheets. Comparisons are made with the structures of some related compounds.

1-Allyl-3-chloro-5-nitro-1H-indazole

PubMed Central

Chicha, Hakima; Rakib, El Mostapha; Spinelli, Domenico; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

In the title compound, C10H8ClN3O2, the indazole ring system makes a dihedral angle of 7.9 (3)° with the plane through the nitro group. The allyl group is rotated out of the plane of the indazole ring system [N—N—C—C torsion angle = 104.28 (19)°]. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming zigzag chains propagating along the b-axis direction. PMID:24427047

1-Allyl-3-chloro-5-nitro-1H-indazole.

PubMed

Chicha, Hakima; Rakib, El Mostapha; Spinelli, Domenico; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

In the title compound, C10H8ClN3O2, the indazole ring system makes a dihedral angle of 7.9 (3)° with the plane through the nitro group. The allyl group is rotated out of the plane of the indazole ring system [N-N-C-C torsion angle = 104.28 (19)°]. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming zigzag chains propagating along the b-axis direction.

Biotransformation of labdane and halimane diterpenoids by two filamentous fungi strains

PubMed Central

Seidl, Cláudia; Severino, Vanessa G. P.; Cardoso, Carmen Lúcia; Castro-Gamboa, Ian

2017-01-01

Biotransformation of natural products by filamentous fungi is a powerful and effective approach to achieve derivatives with valuable new chemical and biological properties. Although diterpenoid substrates usually exhibit good susceptibility towards fungi enzymes, there have been no studies concerning the microbiological transformation of halimane-type diterpenoids up to now. In this work, we investigated the capability of Fusarium oxysporum (a fungus isolated from the rhizosphere of Senna spectabilis) and Myrothecium verrucaria (an endophyte) to transform halimane (1) and labdane (2) acids isolated from Hymenaea stigonocarpa (Fabaceae). Feeding experiments resulted in the production of six derivatives, including hydroxy, oxo, formyl and carboxy analogues. Incubation of 1 with F. oxysporum afforded 2-oxo-derivative (3), while bioconversion with M. verrucaria provided 18,19-dihydroxy (4), 18-formyl (5) and 18-carboxy (6) bioproducts. Transformation of substrate 2 mediated by F. oxysporum produced a 7α-hydroxy (7) derivative, while M. verrucaria yielded 7α- (7) and 3β-hydroxy (8) metabolites. Unlike F. oxysporum, which showed a preference to transform ring B, M. verrucaria exhibited the ability to hydroxylate both rings A and B from substrate 2. Additionally, compounds 1–8 were evaluated for inhibitory activity against Hr-AChE and Hu-BChE enzymes through ICER-IT-MS/MS assay. PMID:29291077

Biotransformation of labdane and halimane diterpenoids by two filamentous fungi strains.

PubMed

Monteiro, Afif F; Seidl, Cláudia; Severino, Vanessa G P; Cardoso, Carmen Lúcia; Castro-Gamboa, Ian

2017-11-01

Biotransformation of natural products by filamentous fungi is a powerful and effective approach to achieve derivatives with valuable new chemical and biological properties. Although diterpenoid substrates usually exhibit good susceptibility towards fungi enzymes, there have been no studies concerning the microbiological transformation of halimane-type diterpenoids up to now. In this work, we investigated the capability of Fusarium oxysporum (a fungus isolated from the rhizosphere of Senna spectabilis ) and Myrothecium verrucaria (an endophyte) to transform halimane ( 1 ) and labdane ( 2 ) acids isolated from Hymenaea stigonocarpa (Fabaceae). Feeding experiments resulted in the production of six derivatives, including hydroxy, oxo, formyl and carboxy analogues. Incubation of 1 with F. oxysporum afforded 2-oxo-derivative ( 3 ), while bioconversion with M. verrucaria provided 18,19-dihydroxy ( 4 ), 18-formyl ( 5 ) and 18-carboxy ( 6 ) bioproducts. Transformation of substrate 2 mediated by F. oxysporum produced a 7 α -hydroxy ( 7 ) derivative, while M. verrucaria yielded 7 α - ( 7 ) and 3 β -hydroxy ( 8 ) metabolites. Unlike F. oxysporum , which showed a preference to transform ring B, M. verrucaria exhibited the ability to hydroxylate both rings A and B from substrate 2 . Additionally, compounds 1 - 8 were evaluated for inhibitory activity against Hr-AChE and Hu-BChE enzymes through ICER-IT-MS/MS assay.

Fast and simultaneous determination of 1 H-1 H and 1 H-19 F scalar couplings in complex spin systems: Application of PSYCHE homonuclear broadband decoupling.

PubMed

Kakita, Veera Mohana Rao; Rachineni, Kavitha; Hosur, Ramakrishna V

2017-07-21

The present manuscript focuses on fast and simultaneous determination of 1 H- 1 H and 1 H- 19 F scalar couplings in fluorinated complex steroid molecules. Incorporation of broadband PSYCHE homonuclear decoupling in the indirect dimension of zero-quantum filtered diagonal experiments (F1-PSYCHE-DIAG) suppresses 1 H- 1 H scalar couplings; however, it retains 1 H- 19 F scalar couplings (along F1 dimension) for the 19 F coupled protons while preserving the pure-shift nature for 1 H resonances uncoupled to 19 F. In such cases, along the direct dimensions, 1 H- 1 H scalar coupling multiplets deconvolute and they appear as duplicated multiplets for the 19 F coupled protons, which facilitates unambiguous discrimination of 19 F coupled 1 H chemical sites from the others. Further, as an added advantage, data acquisition has been accelerated by invoking the known ideas of spectral aliasing in the F1-PSYCHE-DIAG scheme and experiments demand only ~10 min of spectrometer times. Copyright © 2017 John Wiley & Sons, Ltd.

1393 Ring Bus at JPL: Description and Status

NASA Technical Reports Server (NTRS)

Wysocky, Terry R.

2007-01-01

Completed Ring Bus IC V&V Phase - Ring Bus Test Plan Completed for SIM Project - Applicable to Other Projects Implemented a Avionics Bus Based upon the IEEE 1393 Standard - Excellent Starting Point for a General Purpose High-Speed Spacecraft Bus - Designed to Meet SIM Requirements for - Real-time deterministic, distributed systems. - Control system requirements - Fault detection and recovery Other JPL Projects Considering Implementation F'light Software Ring Bus Driver Module Began in 2006, Continues Participating in Standard Revision. Search for Earth-like planets orbiting nearby stars and measure the masses and orbits of the planets it finds. Survey 2000 nearby stars for planetary systems to learn whether our Solar System is unusual, or typical. Make a new catalog of star position 100 times more accurate than current measurements. Learn how our galaxy formed and will evolve by studying the dynamics of its stars. Critically test models of exactly how stars shine, including exotic objects like black holes, neutron stars and white dwarfs.

Pressure broadening and fine-structure-dependent predissociation in oxygen B 3sigma(u)-, v = 0.

PubMed

Hannemann, Sandro; Wu, GuoRong; van Duijn, Eric-Jan; Ubachs, Wim; Cosby, Philip C

2005-11-01

Both laser-induced fluorescence and cavity ring-down spectral observations were made in the Schumann-Runge band system of oxygen, using a novel-type ultranarrow deep-UV pulsed laser source. From measurements on the very weak (0,0) band pressure broadening, pressure shift, and predissociation line-broadening parameters were determined for the B 3sigma(u)-, v = 0,F(i) fine-structure components for various rotational levels in O2. The information content from these studies was combined with that of entirely independent measurements probing the much stronger (0,10), (0,19), and (0,20) Schumann-Runge bands involving preparation of vibrationally excited O2 molecules via photolysis of ozone. The investigations result in a consistent set of predissociation widths for the B 3sigma(u)-, v = 0 state of oxygen.

Analysis of fluorinated proteins by mass spectrometry.

PubMed

Luck, Linda A

2014-01-01

(19)F NMR has been used as a probe for investigating bioorganic and biological systems for three decades. Recent reviews have touted this nucleus for its unique characteristics that allow probing in vivo biological systems without endogenous signals. (19)F nucleus is exceptionally sensitive to molecular and microenvironmental changes and thus can be exploited to explore structure, dynamics, and changes in a protein or molecule in the cellular environment. We show how mass spectrometry can be used to assess and characterize the incorporation of fluorine into proteins. This methodology can be applied to a number of systems where (19)F NMR is used.

Effect of temperature and O-ring gland finish on sealing ability of Viton V747-75

NASA Technical Reports Server (NTRS)

Lach, Cynthia L.

1993-01-01

As a part of the redesign project of the Space Shuttle solid rocket motor (SRM) following the Challenger accident, the field joint was redesigned to minimize the relative joint motion caused by internal motor pressurization during ignition. The O-ring seals and glands for the field joint were designed both to accommodate structural deflections and to promote pressure-assisted sealing. Tests were conducted in various face seal fixtures to evaluate the ability of Viton V747-75 O-rings to seal for a range of temperatures and surface finishes of the redesigned O-ring gland. The effect of surface finish on the sealing performance and wear characteristics of the O-rings was evaluated during simulated launch conditions that included low-frequency vibrations, gap openings, and rapid pressurizations. The effect of contamination on the sealing performance was also investigated. The O-rings sealed throughout the 75 deg F leak check test and for the seal tests from 50 deg F to 120 deg F for the range of surface finishes investigated. Although abrasions were found in the O-rings from pressurization against the rougher finishes, these abrasions were not detrimental to sealing. Below 50 deg F, Viton V747-75 O-rings were insufficiently resilient to track the test gap opening.

The Phylogenetic Signature Underlying ATP Synthase c-Ring Compliance

DOE PAGES

Pandini, Alessandro; Kleinjung, Jens; Taylor, Willie R.; ...

2015-09-01

The proton-driven ATP synthase (F OF 1) is comprised of two rotary, stepping motors (F O and F 1) coupled by an elastic power transmission. The elastic compliance resides in the rotor module that includes the membrane-embedded FO c-ring. Proton transport by FO is firmly coupled to the rotation of the c-ring relative to other F O subunits (ab 2). It drives ATP synthesis. We used a computational method to investigate the contribution of the c-ring to the total elastic compliance. We performed principal component analysis of conformational ensembles built using distance constraints from the bovine mitochondrial c-ring x-ray structure.more » Angular rotary twist, the dominant ring motion, was estimated to show that the c-ring accounted in part for the measured compliance. Ring rotation was entrained to rotation of the external helix within each hairpin-shaped c-subunit in the ring. Ensembles of monomer and dimers extracted from complete c-rings showed that the coupling between collective ring and the individual subunit motions was independent of the size of the c-ring, which varies between organisms. Molecular determinants were identified by covariance analysis of residue coevolution and structural-alphabet-based local dynamics correlations. The residue coevolution gave a readout of subunit architecture. The dynamic couplings revealed that the hinge for both ring and subunit helix rotations was constructed from the proton-binding site and the adjacent glycine motif (IB-GGGG) in the midmembrane plane. IB-GGGG motifs were linked by long-range couplings across the ring, while intrasubunit couplings connected the motif to the conserved cytoplasmic loop and adjacent segments. The correlation with principal collective motions shows that the couplings underlie both ring rotary and bending motions. Noncontact couplings between IB-GGGG motifs matched the coevolution signal as well as contact couplings. The residue coevolution reflects the physiological importance of the dynamics that may link proton transfer to ring compliance.« less

The Phylogenetic Signature Underlying ATP Synthase c-Ring Compliance

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

Pandini, Alessandro; Kleinjung, Jens; Taylor, Willie R.

The proton-driven ATP synthase (F OF 1) is comprised of two rotary, stepping motors (F O and F 1) coupled by an elastic power transmission. The elastic compliance resides in the rotor module that includes the membrane-embedded FO c-ring. Proton transport by FO is firmly coupled to the rotation of the c-ring relative to other F O subunits (ab 2). It drives ATP synthesis. We used a computational method to investigate the contribution of the c-ring to the total elastic compliance. We performed principal component analysis of conformational ensembles built using distance constraints from the bovine mitochondrial c-ring x-ray structure.more » Angular rotary twist, the dominant ring motion, was estimated to show that the c-ring accounted in part for the measured compliance. Ring rotation was entrained to rotation of the external helix within each hairpin-shaped c-subunit in the ring. Ensembles of monomer and dimers extracted from complete c-rings showed that the coupling between collective ring and the individual subunit motions was independent of the size of the c-ring, which varies between organisms. Molecular determinants were identified by covariance analysis of residue coevolution and structural-alphabet-based local dynamics correlations. The residue coevolution gave a readout of subunit architecture. The dynamic couplings revealed that the hinge for both ring and subunit helix rotations was constructed from the proton-binding site and the adjacent glycine motif (IB-GGGG) in the midmembrane plane. IB-GGGG motifs were linked by long-range couplings across the ring, while intrasubunit couplings connected the motif to the conserved cytoplasmic loop and adjacent segments. The correlation with principal collective motions shows that the couplings underlie both ring rotary and bending motions. Noncontact couplings between IB-GGGG motifs matched the coevolution signal as well as contact couplings. The residue coevolution reflects the physiological importance of the dynamics that may link proton transfer to ring compliance.« less

Metabolism of Hydroxylated and Fluorinated Benzoates by Syntrophus aciditrophicus and Detection of a Fluorodiene Metabolite▿

PubMed Central

Mouttaki, Housna; Nanny, Mark A.; McInerney, Michael J.

2009-01-01

Transformations of 2-hydroxybenzoate and fluorobenzoate isomers were investigated in the strictly anaerobic Syntrophus aciditrophicus to gain insight into the initial steps of the metabolism of aromatic acids. 2-Hydroxybenzoate was metabolized to methane and acetate by S. aciditrophicus and Methanospirillum hungatei cocultures and reduced to cyclohexane carboxylate by pure cultures of S. aciditrophicus when grown in the presence of crotonate. Under both conditions, transient accumulation of benzoate but not phenol was observed, indicating that dehydroxylation occurred prior to ring reduction. Pure cultures of S. aciditrophicus reductively dehalogenated 3-fluorobenzoate with the stoichiometric accumulation of benzoate and fluorine. 3-Fluorobenzoate-degrading cultures produced a metabolite that had a fragmentation pattern almost identical to that of the trimethylsilyl (TMS) derivative of 3-fluorobenzoate but with a mass increase of 2 units. When cells were incubated with deuterated water, this metabolite had a mass increase of 3 or 4 units relative to the TMS derivative of 3-fluorobenzoate. 19F nuclear magnetic resonance spectroscopy (19F NMR) detected a metabolite in fluorobenzoate-degrading cultures with two double bonds, either 1-carboxyl-3-fluoro-2,6-cyclohexadiene or 1-carboxyl-3-fluoro-3,6-cyclohexadiene. The mass spectral and NMR data are consistent with the addition of two hydrogen or deuterium atoms to 3-fluorobenzoate, forming a 3-fluorocyclohexadiene metabolite. The production of a diene metabolite provides evidence that S. aciditrophicus contains dearomatizing reductase that uses two electrons to dearomatize the aromatic ring. PMID:19114508

High-pressure cryogenic seals for pressure vessels

NASA Technical Reports Server (NTRS)

Buggele, A. E.

1977-01-01

This investigation of the problems associated with reliably containing gaseous helium pressurized to 1530 bars (22 500 psi) between 4.2 K and 150 K led to the following conclusions: (1) common seal designs used in existing elevated-temperature pressure vessels are unsuitable for high-pressure cryogenic operation, (2) extrusion seal-ring materials such as Teflon, tin, and lead are not good seal materials for cryogenic high-pressure operation; and (3) several high-pressure cryogenic seal systems suitable for large-pressure vessel applications were developed; two seals required prepressurization, and one seal functioned repeatedly without any prepressurization. These designs used indium seal rings, brass or 304 stainless-steel anvil rings, and two O-rings of silicone rubber or Kel-F.

Voyager to the giant planets

NASA Astrophysics Data System (ADS)

Smith, B. A.

The exploration of Jupiter and Saturn by the Pioneer and Voyager probes is reviewed chronologically. Consideration is given to the launching techniques and probe designs; the complex convection patterns in the Jovian atmosphere; the lightning and auroras seen on Jupiter's dark side; the faint Jovian ring; the surfaces of Ganymede, Callisto, and Europa; and the discovery of volcanic activity on Io. The features of Saturn discussed include the earth-like atmospheric jets, the surface and atmosphere of Titan, the orbits of the other satellites, the surface characteristics of Iapetus and Enceladus, the 10,000 ringlets comprising the ring system, the apparent 'spokes' in the rings, and the narrow, knotted F ring. Voyager images of the most significant features are provided.

Crystallographic structure of the turbine C-ring from spinach chloroplast F-ATP synthase

PubMed Central

Balakrishna, Asha Manikkoth; Seelert, Holger; Marx, Sven-Hendric; Dencher, Norbert A.; Grüber, Gerhard

2014-01-01

In eukaryotic and prokaryotic cells, F-ATP synthases provide energy through the synthesis of ATP. The chloroplast F-ATP synthase (CF1FO-ATP synthase) of plants is integrated into the thylakoid membrane via its FO-domain subunits a, b, b’ and c. Subunit c with a stoichiometry of 14 and subunit a form the gate for H+-pumping, enabling the coupling of electrochemical energy with ATP synthesis in the F1 sector. Here we report the crystallization and structure determination of the c14-ring of subunit c of the CF1FO-ATP synthase from spinach chloroplasts. The crystals belonged to space group C2, with unit-cell parameters a=144.420, b=99.295, c=123.51 Å, and β=104.34° and diffracted to 4.5 Å resolution. Each c-ring contains 14 monomers in the asymmetric unit. The length of the c-ring is 60.32 Å, with an outer ring diameter 52.30 Å and an inner ring width of 40 Å. PMID:27919036

Influence of ring size on the cognition-enhancing activity of DM235 and MN19, two potent nootropic drugs.

PubMed

Guandalini, L; Martini, E; Di Cesare Mannelli, L; Dei, S; Manetti, D; Scapecchi, S; Teodori, E; Ghelardini, C; Romanelli, M N

2012-03-01

A series of analogs of DM235 and MN19, characterized by rings with different size, have been prepared and evaluated for their nootropic activity in the mouse passive-avoidance test. It was found that the optimal ring size for the analogs of DM235, showing endocyclic both amidic groups, is 6 or 7 atoms. For the compounds structurally related to MN19, carrying an exocyclic amide group, the piperidine ring is the moiety which gives the most interesting compounds. Copyright © 2012 Elsevier Ltd. All rights reserved.

2,2,2-Trifluoro-1-[3-(2,2,2-trifluoro­acet­yl)azulen-1-yl]ethanone

PubMed Central

Förster, Sebastian; Eissmann, Frank; Seichter, Wilhelm; Weber, Edwin

2011-01-01

There are two mol­ecules in the asymmetric unit of the title compound, C14H6F6O2, in which the azulene systems possess an almost planar geometry with maximum deviations of 0.0438 (15) and 0.0396 (14) Å. Besides intra- and inter­molecular C—H⋯O and C—H⋯F inter­actions, the structure displays three F⋯F contacts [2.793 (2), 2.8820 (17) and 2.9181 (16) Å]. Furthermore, a characteristic azulene π-stacking is observed with an alternating sequence of electron-rich five-membered rings and electron-deficient seven-membered rings [centroid–centroid distances = 3.5413 (12), 3.6847 (12), 3.5790 (12) and 3.7718 (12) Å]. PMID:21754800

Four faces of the interaction between ions and aromatic rings.

PubMed

Papp, Dóra; Rovó, Petra; Jákli, Imre; Császár, Attila G; Perczel, András

2017-07-15

Non-covalent interactions between ions and aromatic rings play an important role in the stabilization of macromolecular complexes; of particular interest are peptides and proteins containing aromatic side chains (Phe, Trp, and Tyr) interacting with negatively (Asp and Glu) and positively (Arg and Lys) charged amino acid residues. The structures of the ion-aromatic-ring complexes are the result of an interaction between the large quadrupole moment of the ring and the charge of the ion. Four attractive interaction types are proposed to be distinguished based on the position of the ion with respect to the plane of the ring: perpendicular cation-π (CP ⊥ ), co-planar cation-π (CP ∥ ), perpendicular anion-π (AP ⊥ ), and co-planar anion-π (AP ∥ ). To understand more than the basic features of these four interaction types, a systematic, high-level quantum chemical study is performed, using the X -  + C 6 H 6 , M +  + C 6 H 6 , X -  + C 6 F 6 , and M +  + C 6 F 6 model systems with X -  = H - , F - , Cl - , HCOO - , CH 3 COO - and M +  = H + , Li + , Na + , NH4+, CH 3 NH3+, whereby C 6 H 6 and C 6 F 6 represent an electron-rich and an electron-deficient π system, respectively. Benchmark-quality interaction energies with small uncertainties, obtained via the so-called focal-point analysis (FPA) technique, are reported for the four interaction types. The computations reveal that the interactions lead to significant stabilization, and that the interaction energy order, given in kcal mol -1 in parentheses, is CP ⊥ (23-37) > AP ⊥ (14-21) > CP ∥ (9-22) > AP ∥ (6-16). A natural bond orbital analysis performed leads to a deeper qualitative understanding of the four interaction types. To facilitate the future quantum chemical characterization of ion-aromatic-ring interactions in large biomolecules, the performance of three density functional theory methods, B3LYP, BHandHLYP, and M06-2X, is tested against the FPA benchmarks, with the result that the M06-2X functional performs best. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

F Ring Core Stability: Corotation Resonance Plus Antiresonance

NASA Astrophysics Data System (ADS)

Cuzzi, Jeffrey N.; Marouf, Essam; French, Richard; Jacobson, Robert

2014-11-01

The decades-or-longer stability of the narrow F Ring core in a sea of orbital chaos appears to be due to an unusual combination of traditional corotation resonance and a novel kind of “antiresonance”. At a series of specific locations in the F Ring region, apse precession between synodic encounters with Prometheus allows semimajor axis perturbations to promptly cancel before significant orbital period changes can occur (Cuzzi et al. 2014, Icarus 232, 157-175). This cancellation fails for particles that encounter Prometheus when it is near its apoapse, especially during periods of antialignment of its apse with that of the F Ring. At these times, the strength of the semimajor axis perturbation is large (tens of km) and highly nonsinusoidal in encounter longitude, making it impossible to cancel promptly on a subsequent encounter and leading to chaotic orbital diffusion. Only particles that consistently encounter Prometheus away from its apoapse can use antiresonance to maintain stable orbits, implying that the true mean motion nF of the stable core must be defined by a corotational resonance of the form nF = nP-κP/m, where (nP, κP) are Prometheus’ mean motion and epicycle frequency. To test this hypothesis we used the fact that Cassini RSS occultations only sporadically detect a “massive” F Ring core, composed of several-cm-and-larger particles. We regressed the inertial longitudes of 24 Cassini RSS (and VGR) detections and 43 nondetections to a common epoch, using a comb of candidate nP, and then folded them modulo the anticipated m-number of the corotational resonance (Prometheus m=110 outer CER), to see if clustering appears. We find the “true F Ring core” is actually arranged in a series of short longitudinal arcs separated by nearly empty longitudes, orbiting at a well determined semimajor axis of 140222.4km (from 2005-2012 at least). Small particles seen by imaging and stellar occultations spread quickly in azimuth and obscure this clumpy structure. Small chaotic variations in the mean motion and/or apse longitude of Prometheus quickly become manifest in the F Ring core, and we suggest that the core must adapt to these changes for the F Ring to maintain stability over timescales of decades and longer.

BPM System for Electron Cooling in the Fermilab Recycler Ring

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

Joireman, Paul W.; Cai, Jerry; Chase, Brian E.

2004-11-10

We report a VXI based system used to acquire and process BPM data for the electron cooling system in the Fermilab Recycler ring. The BPM system supports acquisition of data from 19 BPM locations in five different sections of the electron cooling apparatus. Beam positions for both electrons and anti-protons can be detected simultaneously with a resolution of {+-}50 {mu}m. We calibrate the system independently for each beam type at each BPM location. We describe the system components, signal processing and modes of operation used in support of the electron-cooling project and present experimental results of system performance for themore » developmental electron cooling installation at Fermilab.« less

High temperature lubricant screening and systems studies

NASA Technical Reports Server (NTRS)

Jones, D. A.

1973-01-01

Four candidate lubricants for next generation aircraft gas turbine application were tested under open atmosphere conditions in a rig simulating an advanced engine 125 mm bore mainshaft thrust bearing position. Testing was conducted at speeds to 24,000 rpm (3,000,000 bearing DN), bearing ring temperature of 500 F, and with 1200 F air and 100 psi differential pressure across the seals installed in a dual tandem arrangement. Test bearing was a 125 mm bore split inner ring, outer race riding angular contact ball bearing under a 3280 lb. thrust load. One lubricant, a type 2 ester, performed extremely well. The mainshaft seal limited the performance. Numerous design improvements for this seal were indicated.

Cassini RADAR End of Mission Calibration and Preliminary Ring Results

NASA Astrophysics Data System (ADS)

West, R. D.; Janssen, M.; Zhang, Z.; Cuzzi, J. N.; Anderson, Y.; Hamilton, G.

2017-12-01

The Cassini mission is in the midst of its last year of observations. Part of the mission plan includes orbits that bring the spacecraft close to Saturn's rings prior to deorbiting into Saturn's atmosphere. First, a series of F-ring orbits crossed the ring plane just outside of the F-ring, and then a series of Proximal orbits crossed the ring plane inside of the D-ring - just above the cloud tops. The Cassini RADAR instrument collected active and passive data of the rings in 5 observations, of Saturn in one observation, and passive only data in an additional 4 observations. These observations provided a unique opportunity to obtain backscatter measurements and relatively high-resolution brightness temperature measurements from Saturn and the rings. Such measurements were never before possible from the spacecraft or the Earth due to high range. Before the F-ring orbits began, and again during the last rings scan, the radar collected calibration data to aid calibration of the rings measurements and to provide an updated timeline of the radar calibration over the whole mission. This presentation will cover preliminary processing results from the radar rings scans and from the calibration data sets. Ultimately, these ring scan measurements will provide a 1-D profile of backscatter obtained at 2.2 cm wavelength that will complement similar passive profiles obtained at optical, infrared, and microwave wavelengths. Such measurements will further constrain and inform models of the ring particle composition and structure, and the local vertical structure of the rings. This work is supported by the NASA Cassini Program at JPL - CalTech.

Reengineering of the feedback-inhibition enzyme N-acetyl-L-glutamate kinase to enhance L-arginine production in Corynebacterium crenatum.

PubMed

Zhang, Jingjing; Xu, Meijuan; Ge, Xiaoxun; Zhang, Xian; Yang, Taowei; Xu, Zhenghong; Rao, Zhiming

2017-02-01

N-acetyl-L-glutamate kinase (NAGK) catalyzes the second step of L-arginine biosynthesis and is inhibited by L-arginine in Corynebacterium crenatum. To ascertain the basis for the arginine sensitivity of CcNAGK, residue E19 which located at the entrance of the Arginine-ring was subjected to site-saturated mutagenesis and we successfully illustrated the inhibition-resistant mechanism. Typically, the E19Y mutant displayed the greatest deregulation of L-arginine feedback inhibition. An equally important strategy is to improve the catalytic activity and thermostability of CcNAGK. For further strain improvement, we used site-directed mutagenesis to identify mutations that improve CcNAGK. Results identified variants I74V, F91H and K234T display higher specific activity and thermostability. The L-arginine yield and productivity of the recombinant strain C. crenatum SYPA-EH3 (which possesses a combination of all four mutant sites, E19Y/I74V/F91H/K234T) reached 61.2 and 0.638 g/L/h, respectively, after 96 h in 5 L bioreactor fermentation, an increase of approximately 41.8% compared with the initial strain.

Particle–hole ring diagrams for fermions in two dimensions

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

Kaiser, N., E-mail: nkaiser@ph.tum.de

2014-11-15

The set of particle–hole ring diagrams for a many-fermion system in two dimensions is studied. The complex-valued polarization function is derived in detail and shown to be expressible in terms of square-root functions. For a contact-interaction the perturbative contributions to the energy per particle Ē(k{sub f}) are calculated in a closed analytical form from third up to twelfth order. The resummation of the particle–hole ring diagrams to all orders is studied and a pronounced dependence on the dimensionless coupling parameter α is found. There is a substantial difference between the complete ring-sum with all exchange-type diagrams included and the standardmore » resummation of the leading n-ring diagrams only. The spin factor S{sub n}(g) associated to the nth order ring diagrams is derived for arbitrary spin-degeneracy g.« less

Methanol fractionations of Catha edulis Frosk (Celastraceae) contracted Lewis rat aorta in vitro: a comparison between crimson and green leaves.

PubMed

Mahmood, Samira Abdulla; Pavlovic, Dragan; Hoffmann, Ulrich

2009-05-07

The study investigated the effect of methanol extract and its fractionations obtained from Yemeni khat on the smooth muscle isometric tension in Lewis rat aortal ring preparations and compared the effects of the crimson and green leaves. Khat leaves were sorted into green (khat Light; KL) and crimson (khat Dark; KD) leaves, extracted with methanol, followed with solvent-solvent extraction (benzene, chloroform and ethylacetate). The contractile activity of the fractions was tested using aortal ring preparations. The control (phenylepherine contraction) methanol extracts contracted aortas at concentrations 250, 125 and 67.5 microg/ml buffer by 80.2%, 57.3%, 26.4% and 81.5%, 65.6%, 24.6% for KL and KD, respectively. Fractions of benzene (BF) and ethylacetate (EaF) contracted the aorta with 2 microgm, whereas, chloroform (ChF) with 1 microgm/1 ml buffer was less potent. The shape of contraction curve produced by EaF differed from that of ChF and BF of both (KL and KD). The EaF induced-contraction peaked after 3.3 +/- 0.94 mins, whereas those of BF and CHF peaked after 18.0 +/- 2.2, 19.7 +/- 0.94 mins, respectively. Pre-incubation with nifedipine (10(-6) M) insignificantly reduced the contraction induced by all fractionations, but prazosin (10(-6) M) reduced the contraction by 81.9%, 63.1%, 71.8% with p = 0.23, 0.09, 0.15 for BF, ChF and EaF of KL, respectively. It significantly reduced contraction of ChF, 64.1%; p = 0.02, and of EaF, 73.5%; p = 0.04 of KD, while the reduction in contraction of BF was 63.1%; p = 0.06. In conclusion, fractions of green and crimson Yemeni khat leaves contracted aortas of Lewis rats. Both leaves behave almost similarly. Contraction induced by chloroform fraction produced alpha-sympathetic activity.

Simulating Local Area Network Protocols with the General Purpose Simulation System (GPSS)

DTIC Science & Technology

1990-03-01

generation 15 3.1.2 Frame delivery . 15 3.2 Model artifices 16 3.3 Model variables 17 3.4 Simulation results 18 4. EXTERNAL PROCEDURES USED IN SIMULATION 19...46 15. Token Ring: Frame generation process 47 16. Token Ring: Frame delivery process 48 17 . Token Ring: Mean transfer delay vs mean throughput 49...assumed to be zero were replaced by the maximum values specified in the ANSI 802.3 standard (viz &MI=6, &M2=3, &M3= 17 , &D1=18, &D2=3, &D4=4, &D7=3, and

Development of a sustained fluoride delivery system.

PubMed

Baturina, Olga; Tufekci, Eser; Guney-Altay, Ozge; Khan, Shadeed M; Wnek, Gary E; Lindauer, Steven J

2010-11-01

To develop a novel delivery system by which fluoride incorporated into elastomeric rings, such as those used to ligate orthodontic wires, will be released in a controlled and constant manner. Polyethylene co-vinyl acetate (PEVA) was used as the model elastomer. Samples (N = 3) were prepared by incorporating 0.02 to 0.4 g of sodium fluoride (NaF) into previously prepared PEVA solution. Another group of samples prepared in the same manner were additionally dip-coated in PEVA to create an overcoat. Fluoride release studies were conducted in vitro using an ion selective electrode over a period of 45 days. The amount of fluoride released was compared to the optimal therapeutic dose of 0.7 microg F(-)/ring/d. Only coated samples with the highest fluoride content (group D, 0.4 g of NaF) were able to release fluoride at therapeutic levels. When fluoride release from coated and uncoated samples with the same amount of NaF were compared, it was shown that the dip-coating technique resulted in a fluoride release in a controlled manner while eliminating the initial burst effect. This novel fluoride delivery matrix provided fluoride release at a therapeutically effective rate and profile.

The effect of perfluorination on the aromaticity of benzene and heterocyclic six-membered rings.

PubMed

Wu, Judy I; Pühlhofer, Frank G; Schleyer, Paul von Ragué; Puchta, Ralph; Kiran, Boggavarapu; Mauksch, Michael; Hommes, Nico J R van Eikema; Alkorta, Ibon; Elguero, José

2009-06-18

Despite having six highly electronegative F's, perfluorobenzene C(6)F(6) is as aromatic as benzene. Ab initio block-localized wave function (BLW) computations reveal that both C(6)F(6) and benzene have essentially the same extra cyclic resonance energies (ECREs). Localized molecular orbital (LMO)-nucleus-independent chemical shifts (NICS) grids demonstrates that the F's induce only local paratropic contributions that are not related to aromaticity. Thus, all of the fluorinated benzenes (C(6)F(n)H((6-n)), n = 1-6) have similar ring-LMO-NICS(pi zz) values. However, 1,3-difluorobenzene 2b and 1,3,5-trifluorobenzene 3c are slightly less aromatic than their isomers due to a greater degree of ring charge alternation. Isoelectronic C(5)H(5)Y heterocycles (Y = BH(-), N, NH(+)) are as aromatic as benzene, based on their ring-LMO-NICS(pi zz) and ECRE values, unless extremely electronegative heteroatoms (e.g., Y = O(+)) are involved.

Orbital Evolution of Particles and Stable Zones at the F Ring Core

NASA Astrophysics Data System (ADS)

Whizin, Akbar; Cuzzi, J.; Hogan, R.; Dobrovolskis, A.; Colwell, J.; Scargle, J.; Dones, L.; Showalter, M.

2012-10-01

The F ring of Saturn is often thought of as a ‘shepherded’ ring; however, it is closer to the more massive of its two shepherd satellites, Prometheus. Pandora, the outer satellite, is near a 3:2 mean motion resonance with larger Mimas causing periodic fluctuations in its orbit. The perturbations from the Saturnian satellites result in chaotic orbits throughout the F ring region (Scargle et al 1993 DPS 25, #26.04, Winter et al 2007 MNRAS 380, L54; 2010 A&A 523, A67). We follow the approach of Cuzzi et al. (abstract this meeting) in exploring zones of relative stability in the F ring region using a N-body Bulirsch-Stoer orbital integrator that includes the 14 main satellites of Saturn. We find relatively stable zones situated among the tightly packed Prometheus and Pandora resonances that we dub “anti-resonances.” At these locations ring particles have much smaller changes in their semi-major axes and eccentricities than particles outside of anti-resonance zones. We present high radial resolution simulations where we track the orbital evolution of 6000 test particles over time in a 200km region and find that the variance of the semi-major axes of particles in anti-resonances can be less than 1km over a period of 32 years, while just 5km away in either radial direction the variance can be tens of km’s. More importantly, particles outside of these stable zones can migrate into one due to chaotic orbits, but once they enter an anti-resonance zone they remain there. The anti-resonances act as long-lived sinks for ring particles and explain the location of the F ring core even though it is not in overall torque balance with the shepherd moons.

Deep HST/STIS Visible-Light Imaging of Debris Systems Around Solar Analog Hosts

NASA Technical Reports Server (NTRS)

Schneider, Glenn; Grady, Carol A.; Stark, Christopher C.; Gaspar, Andras; Carson, Joseph; Debes, John H.; Henning, Thomas; Hines, Dean C.; Jang-Condell, Hannah; Kuchner, Marc J.

2016-01-01

We present new Hubble Space Telescope observations of three a priori known starlight-scattering circumstellar debris systems (CDSs) viewed at intermediate inclinations around nearby close-solar analog stars: HD 207129, HD202628, and HD 202917. Each of these CDSs possesses ring-like components that are more massive analogs of our solar systems Edgeworth Kuiper Belt. These systems were chosen for follow-up observations to provide imaging with higher fidelity and better sensitivity for the sparse sample of solar-analog CDSs that range over two decades in systemic ages, with HD 202628 and HD 207129 (both approx. 2.3 Gyr) currently the oldest CDSs imaged in visible or near-IR light. These deep (10-14 ks) observations, made with six-roll point-spread-function template visible-light coronagraphy using the Space Telescope Imaging Spectrograph, were designed to better reveal their angularly large debris rings of diffuse low surface brightness, and for all targets probe their exo-ring environments for starlight-scattering materials that present observational challenges for current ground-based facilities and instruments. Contemporaneously also observing with a narrower occulter position, these observations additionally probe the CDS endo-ring environments that are seen to be relatively devoid of scatterers. We discuss the morphological, geometrical, and photometric properties of these CDSs also in the context of other CDSs hosted by FGK stars that we have previously imaged as a homogeneously observed ensemble. From this combined sample we report a general decay in quiescent-disk F disk /F star optical brightness approx. t( exp.-0.8), similar to what is seen at thermal IR wavelengths, and CDSs with a significant diversity in scattering phase asymmetries, and spatial distributions of their starlight-scattering grains.

Rings in astronomy and cosmology, 1600-1900

NASA Astrophysics Data System (ADS)

van Helden, A.

It was not until the 1640s that Descartes proposed a cosmology in which the universe is filled with vortices of invisible matter, and Huygens (1659) subsequently solved the problem posed by Saturn's telescopic appearances by postulating that the planet is surrounded by a ring. As Cartesian vortices fell out of favor in the mid-1700s, Kant and Lambert suggested cosmologies in which the galaxies were enormous disks of rotating matter. Over most of the 19th century, Laplace's nebular hypothesis was held to be supported by the increasing number of asteroids as well as the particle nature of Saturn's rings. More recently, rings of dispersed matter have played a prominent role in theories of the origin of the solar system.

Neutral O2 and Ion O2+ Sources from Rings into the Inner Magnetosphere

NASA Astrophysics Data System (ADS)

Elrod, M. K.; Johnson, R. E.; Cassidy, T. A.; Wilson, R. J.; Tseng, W.; Ip, W.

2009-12-01

The primary source of neutral O2 for Saturn’s magnetosphere is due to solar UV photons protons that produce O2 from H2O ice decomposition over the main rings as well as the tenuous F and G rings resulting in a tenuous O2 atmosphere (Johnson et. al. 2006). The O2 atmosphere is very thin to the point of being nearly collisionless. Our model of the atmosphere predict that as it interacts with the ring particles, the O2 is adsorbed and desorbed from the rings causing changes in the trajectories, which in turn, allows for a distribution of O2 from the rings throughout the magnetosphere (Tokar et. al. 2005; Tseng et. al. 2009). Predominately through photo-ionization and ion-exchange these O2 neutrals from the ice grains become a source for O2+ ions in the inner magnetosphere. Once the O2 becomes ionized to become O2+ the ions then follow the field lines. The ions interact with the ice particles in the rings to stick to the ring particles effectively reducing the ion density. As a result the ion density is greater over the Cassini Division and the area between the F and G ring where the optical depth due to the ice grain is less. Accordingly, the neutral O2 densities would tend to be high over the higher optical depth of the B and A main rings where the source rates are higher. Models of the neutral densities have shown high densities over the main rings, with a tail through the magnetosphere. Analysis of the CAPS (Cassini Plasma Spectrometer) data from the Saturn Orbit Insertion (SOI) in 2004 shows a peak in density over the Cassini Division and a higher peak in O2+ ion density between the F and G rings. References: Johnson, R.E., J.G. Luhmann, R.L. Tokar, M. Bouhram, J.J. Berthelier, E.C. Siler, J.F. Cooper, T.W. Hill, H.T. Smith, M. Michael, M. Liu, F.J. Crary, D.T. Young, "Production, Ionization and Redistribution of O2 Saturn's Ring Atmosphere" Icarus 180, 393-402 (2006).(pdf) Tokar, R.L., and 12 colleagues, 2005. Cassini Observations of the Thermal Plasma in the Vicinity of Saturn’s Main Rings and the F and G Rings. Geophys. Res. Lett. 32, doi:10.1029/2005GL022690. L14S04. Martens, H. R., Reisenfeld, D. B., Williams, J. D., Johnson, R.E., Smith H. T., “Observations of molecular oxygen ions in Saturn’s inner magnetosphere”. Geophy. Res. Lett. 2009. W.-L. Tseng, Ip, W.-H., Johnson, R. E., Cassidy, T. A., Elrod, M. K., “The Structure and Time Variability of the Ring atmosphere and ionosphere”. Geophy. Res. Lett. 2009.

Effect of hydrodynamical-simulation–inspired dark matter velocity profile on directional detection of dark matter

DOE PAGES

Laha, Ranjan

2018-02-01

Directional detection is an important way to detect dark matter. An input for these experiments is the dark matter velocity distribution. Recent hydrodynamical simulations have shown that the dark matter velocity distribution differs substantially from the Standard Halo Model. We study the impact of some of these updated velocity distributions in dark matter directional detection experiments. Here, we calculate the ratio of events required to confirm the forward-backward asymmetry and the existence of the ring of maximum recoil rate using different dark matter velocity distributions for 19F and Xe targets. We show that with the use of updated dark mattermore » velocity profiles, the forward-backward asymmetry and the ring of maximum recoil rate can be confirmed using a factor of ~ 2– 3 less events when compared to that using the Standard Halo Model.« less

Effect of hydrodynamical-simulation–inspired dark matter velocity profile on directional detection of dark matter

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

Laha, Ranjan

Directional detection is an important way to detect dark matter. An input for these experiments is the dark matter velocity distribution. Recent hydrodynamical simulations have shown that the dark matter velocity distribution differs substantially from the Standard Halo Model. We study the impact of some of these updated velocity distributions in dark matter directional detection experiments. Here, we calculate the ratio of events required to confirm the forward-backward asymmetry and the existence of the ring of maximum recoil rate using different dark matter velocity distributions for 19F and Xe targets. We show that with the use of updated dark mattermore » velocity profiles, the forward-backward asymmetry and the ring of maximum recoil rate can be confirmed using a factor of ~ 2– 3 less events when compared to that using the Standard Halo Model.« less

Stiffness of γ subunit of F(1)-ATPase.

PubMed

Okuno, Daichi; Iino, Ryota; Noji, Hiroyuki

2010-11-01

F(1)-ATPase is a molecular motor in which the γ subunit rotates inside the α(3)β(3) ring upon adenosine triphosphate (ATP) hydrolysis. Recent works on single-molecule manipulation of F(1)-ATPase have shown that kinetic parameters such as the on-rate of ATP and the off-rate of adenosine diphosphate (ADP) strongly depend on the rotary angle of the γ subunit (Hirono-Hara et al. 2005; Iko et al. 2009). These findings provide important insight into how individual reaction steps release energy to power F(1) and also have implications regarding ATP synthesis and how reaction steps are reversed upon reverse rotation. An important issue regarding the angular dependence of kinetic parameters is that the angular position of a magnetic bead rotation probe could be larger than the actual position of the γ subunit due to the torsional elasticity of the system. In the present study, we assessed the stiffness of two different portions of F(1) from thermophilic Bacillus PS3: the internal part of the γ subunit embedded in the α(3)β(3) ring, and the complex of the external part of the γ subunit and the α(3)β(3) ring (and streptavidin and magnetic bead), by comparing rotational fluctuations before and after crosslinkage between the rotor and stator. The torsional stiffnesses of the internal and remaining parts were determined to be around 223 and 73 pNnm/radian, respectively. Based on these values, it was estimated that the actual angular position of the internal part of the γ subunit is one-fourth of the magnetic bead position upon stalling using an external magnetic field. The estimated elasticity also partially explains the accommodation of the intrinsic step size mismatch between F(o) and F(1)-ATPase.

Reproducing impact ionization mass spectra of E and F ring ice grains at different impact speeds

NASA Astrophysics Data System (ADS)

Klenner, F.; Reviol, R.; Postberg, F.

2017-09-01

As impact speeds of E and F ring ice grains impinging onto the target of impact ionization mass spectrometers in space can vary greatly, the resulting cationic or anionic mass spectra can have very different appearances. The mass spectra can be accurately reproduced with an analog experimental setup IR-FL-MALDI-ToF-MS (Infrared Free Liquid Matrix Assisted Laser Desorption and Ionization Time of Flight Mass Spectrometry). We compare mass spectra of E and F ring ice grains taken by the Cosmic Dust Analyzer (CDA) onboard Cassini recorded at different impact speeds with our analog spectra and prove the capability of the analog experiment.

Crystal structure of (E)-1-[4-({4-[(4-meth­oxy­benzyl­idene)amino]­phen­yl}sulfan­yl)phen­yl]ethan-1-one

PubMed Central

Hebbachi, Rabihe; Djedouani, Amel; Kadri, Soumia; Mousser, Hénia; Mousser, Abdelhamid

2015-01-01

The title Schiff base compound, C22H19NO2S, crystallized with two independent mol­ecules (A and B) in the asymmetric unit. Both mol­ecules have an E conformation about the C=N bond. The two mol­ecules differ in the orientation of the aromatic rings with respect to each other. The outer 4-meth­oxy­benzene ring is inclined to the central benzene ring and the outer 4-acetyl­benzene ring by 1.80 (19) and 63.73 (19)°, respectively, in mol­ecule A, and by 6.72 (18) and 68.53 (19)°, respectively, in mol­ecule B. The two outer benzene rings are inclined to one another by 63.77 (18) and 63.19 (18)° in mol­ecules A and B, respectively. In the crystal, the individual mol­ecules stack in columns along [010], and are linked by a number of C—H⋯π inter­actions, forming slabs lying parallel to (001). PMID:25878856

Cephalopod-INspired Adaptive Photonic SystEms (CINAPSE)

DTIC Science & Technology

2013-09-13

2013 19.00 L. M. Mathger, G. R. R. Bell, A. M. Kuzirian, J. J. Allen, R. T. Hanlon. How does the blue - ringed octopus (Hapalochlaena lunulata) flash...its blue rings ?, Journal of Experimental Biology, (10 2012): 3752. doi: 10.1242/jeb.076869 08/28/2013 20.00 T. J. Wardill, P. T. Gonzalez-Bellido, R...distinct fluorescent emission spectrum shift into the near-red wavelengths (610-630 ¿) when excited by a 514 ¿ ( blue -green) laser beam. The

19F DOSY NMR analysis for spin systems with nJFF couplings.

PubMed

Dal Poggetto, Guilherme; Favaro, Denize C; Nilsson, Mathias; Morris, Gareth A; Tormena, Cláudio F

2014-04-01

NMR is a powerful method for identification and quantification of drug components and contaminations. These problems present themselves as mixtures, and here, one of the most powerful tools is DOSY. DOSY works best when there is no spectral overlap between components, so drugs containing fluorine substituents are well-suited for DOSY analysis as (19)F spectra are typically very sparse. Here, we demonstrate the use of a modified (19)F DOSY experiment (on the basis of the Oneshot sequences) for various fluorinated benzenes. For compounds with significant (n) JFF coupling constants, as is common, the undesirable J-modulation can be efficiently suppressed using the Oneshot45 pulse sequence. This investigation highlights (19)F DOSY as a valuable and robust method for analysis of molecular systems containing fluorine atoms even where there are large fluorine-fluorine couplings. Copyright © 2014 John Wiley & Sons, Ltd.

Dynamics and kinetics of narrow dusty ringlets

NASA Astrophysics Data System (ADS)

Sun, K. L.; Spahn, F.; Schmidt, J.

2011-10-01

Several narrow dusty rings have been discovered in the Saturn system, such as the F ring, ringlets in the C Ring, the Cassini division, and the Encke Gap [1] [2]. The kinky and clumpy structures in the F ring are considered as the result of embedded moonlets which are dynamically dominated by shepherding moons [3]. Similar features are found in Encke ringlets which we hypothesize to be associated with embedded moonlets [4] [5]. On the other hand, these ringlets are believed to be composed of micron-sized particles [6], which are strongly perturbed by solar radiation pressure and their lifetime is restricted. Therefore mechanisms must be at work to replenish these ringlets. We develop a model for the kinetic balance of dust production, dynamical evolution, and sinks by assuming that dust is freed and annihilated by moonlets embedded in the ringlet. The dynamics of particles ejected from these putative moonlets is explored and the contribution of impact-ejecta to the ringlet is estimated [7] [8]. We found that the optical depth sustained by embedded moonlets is too low (orders of magnitude), indicating that other sources or processes should be responsible for supporting the Encke ringlet.

The Brightening of Saturn's F Ring

NASA Astrophysics Data System (ADS)

Showalter, Mark R.; French, R.; Sfair, R.; Argüelles, C.; Pajuelo, M.; Becerra, P.; Hedman, M.; Nicholson, P.

2009-09-01

A substantial secular increase in the brightness of Saturn's F ring has occurred in the last 25 years. The ring is twice as bright in the Cassini data as it was in the Voyager data from 1980 and 1981. However, no changes have been measured since the Cassini tour began in 2004. These conclusions are based on the photometric analysis of 3500 Cassini images taken primarily through clear filters, as compared to an earlier analysis of 67 Voyager images (Icarus 100, 394-411, 1992). Analysis of the large number of images has enabled us to average out the intrinsic longitudinal variations in the ring. The shapes of the phase curves from Cassini and Voyager are similar, suggesting that although the number of dust particles has increased, the overall distribution of sizes is unchanged. The color of the ring is neutral, and photometric models point to a power law size distribution with differential slope in the range 3 to 4. Eleven stellar occultation profiles from Cassini VIMS are consistent with the above factor-of-two change. They show consistently higher integrated optical depths than were measured by Voyager during its single stellar occultation. The F ring's peculiar dynamics are dominated by perturbations from Prometheus and Pandora, plus impacts from smaller clumps orbiting nearby. This work indicates that the amount of ring dust is highly variable on time scales of decades. This suggests that dust production is probably not dominated by the relatively frequent impacts of nearby clumps. The variations are consistent with the time scale for mutual precession of the nearby moons relative to the F ring. It implies a "seasonal" aspect to the dust production, in which dust increases whenever mutual precession allows a moon to rotate into a ring-approaching orbit.

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

Schneider, Glenn; Gaspar, Andras; Grady, Carol A.

We present new Hubble Space Telescope observations of three a priori known starlight-scattering circumstellar debris systems (CDSs) viewed at intermediate inclinations around nearby close-solar analog stars: HD 207129, HD 202628, and HD 202917. Each of these CDSs possesses ring-like components that are more massive analogs of our solar system's Edgeworth–Kuiper Belt. These systems were chosen for follow-up observations to provide imaging with higher fidelity and better sensitivity for the sparse sample of solar-analog CDSs that range over two decades in systemic ages, with HD 202628 and HD 207129 (both ∼2.3 Gyr) currently the oldest CDSs imaged in visible or near-IRmore » light. These deep (10–14 ks) observations, made with six-roll point-spread-function template visible-light coronagraphy using the Space Telescope Imaging Spectrograph, were designed to better reveal their angularly large debris rings of diffuse/low surface brightness, and for all targets probe their exo-ring environments for starlight-scattering materials that present observational challenges for current ground-based facilities and instruments. Contemporaneously also observing with a narrower occulter position, these observations additionally probe the CDS endo-ring environments that are seen to be relatively devoid of scatterers. We discuss the morphological, geometrical, and photometric properties of these CDSs also in the context of other CDSs hosted by FGK stars that we have previously imaged as a homogeneously observed ensemble. From this combined sample we report a general decay in quiescent-disk F {sub disk}/ F {sub star} optical brightness ∼ t {sup −0.8}, similar to what is seen at thermal IR wavelengths, and CDSs with a significant diversity in scattering phase asymmetries, and spatial distributions of their starlight-scattering grains.« less

49 CFR Appendix A to Part 214 - Schedule of Civil Penalties 1

Code of Federal Regulations, 2011 CFR

2011-10-01

... ring bouys 5,000 10,000 (ii) Failure to use ring bouys 1,500 (f)(i) Failure to provide skiff 1,000 2,500 (ii) Failure to use skiff 1,500 214.109 Scaffolding: (a)-(f) Failure to provide conforming... approach warning signal 2,000 (e) Failure to communicate proper warning signal 1,500 3,000 (f)(1...

49 CFR Appendix A to Part 214 - Schedule of Civil Penalties 1

Code of Federal Regulations, 2012 CFR

2012-10-01

... ring bouys 5,000 10,000 (ii) Failure to use ring bouys 1,500 (f)(i) Failure to provide skiff 1,000 2,500 (ii) Failure to use skiff 1,500 214.109 Scaffolding: (a)-(f) Failure to provide conforming... train approach warning signal 2,000 (e) Failure to communicate proper warning signal 1,500 3,000 (f)(1...

49 CFR Appendix A to Part 214 - Schedule of Civil Penalties 1

Code of Federal Regulations, 2014 CFR

2014-10-01

... ring bouys 5,000 10,000 (ii) Failure to use ring bouys 1,500 (f)(i) Failure to provide skiff 1,000 2,500 (ii) Failure to use skiff 1,500 214.109 Scaffolding: (a)-(f) Failure to provide conforming... approach warning signal 2,000 (e) Failure to communicate proper warning signal 1,500 3,000 (f)(1...

48 CFR 19.1101 - General.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false General. 19.1101 Section 19.1101 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SOCIOECONOMIC PROGRAMS... requirements set forth in 13 CFR 124.1002(f) are met. ...

TMC Behavior Modeling and Life Prediction Under Multiaxial Stresses

NASA Technical Reports Server (NTRS)

Merrick, H. F.; Aksoy, S. Z.; Costen, M.; Ahmad, J.

1998-01-01

The goal of this program was to manufacture and burst test small diameter SCS-6/Ti-6Al-4V composite rings for use in the design of an advanced titanium matrix composite (TMC) impeller. The Textron Specialty Metals grooved foil-fiber process was successfully used to make high quality TMC rings. A novel spin test arbor with "soft touch" fingers to retain the TMC ring was designed and manufactured. The design of the arbor took into account its use for cyclic experiments as well as ring burst tests. Spin testing of the instrumented ring was performed at ambient, 149C (300F), and 316C (600F) temperatures. Assembly vibration was encountered during spin testing but this was overcome through simple modification of the arbor. A spin-to-burst test was successfully completed at 316C (600F). The rotational speed of the TMC ring at burst was close to that predicted. In addition to the spin test program, a number of SCS-6/Ti-6Al-4V test panels were made. Neat Ti-6Al-4V panels also were made.

Bond-equilibrium theory of liquid Se-Te alloys. II. Effect of singly attached ring molecules

NASA Astrophysics Data System (ADS)

Cutler, Melvin; Bez, Wolfgang G.

1981-06-01

A statistical-mechanical theory for bond equilibrium of chain polymers containing threefold (3F) and onefold (1F) bond defects is extended to include the effects of free ring molecules and ring molecules attached to chains by a single 3F atom. Positively charged singly attached rings are shown to play a key role in bond equilibrium in liquid Sex Te1-x by permitting the formation of ion pairs in which both constituents are effectively chain terminators, thus decreasing the average polymer size. The theory is applied to explain the behavior of the paramagnetic susceptibility, χp, and electronic transport as affected by the Fermi energy EF. It is found that the increase in χp with the concentration of Te is primarily the result of the smaller energy for breaking Te bonds. In addition, attached rings play an important role in determining the effect of temperature on χp. At x<~0.5, the concentrations of both free and attached rings becomes small at high T because of the high concentration of bond defects.

Nanograin Density Outside Saturn’s A Ring

NASA Astrophysics Data System (ADS)

Johnson, Robert E.; Tseng, Wei-Ling; Elrod, M. K.; Persoon, A. M.

2017-01-01

The observed disparity between the radial dependence of the ion and electron densities measured by the Cassini plasma (CAPS) and radio (RPWS) science instruments are used to show that the region between the outer edge of Saturn’s main rings and its tenuous G ring is permeated with small charged grains (nanograins). These grains emanate from the edge of the A ring and from the tenuous F and G rings. This is a region of Saturn’s magnetosphere that is relatively unexplored, but will be a focus of Cassini’s F ring orbits prior to the end of mission in 2017 September. Confirmation of the grain densities predicted here will enhance our ability to describe the formation and destruction of material in this important region of Saturn’s magnetosphere.

NANOGRAIN DENSITY OUTSIDE SATURN’S A RING

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

Johnson, Robert E.; Tseng, Wei-Ling; Elrod, M. K.

The observed disparity between the radial dependence of the ion and electron densities measured by the Cassini plasma (CAPS) and radio (RPWS) science instruments are used to show that the region between the outer edge of Saturn’s main rings and its tenuous G ring is permeated with small charged grains (nanograins). These grains emanate from the edge of the A ring and from the tenuous F and G rings. This is a region of Saturn’s magnetosphere that is relatively unexplored, but will be a focus of Cassini ’s F ring orbits prior to the end of mission in 2017 September.more » Confirmation of the grain densities predicted here will enhance our ability to describe the formation and destruction of material in this important region of Saturn’s magnetosphere.« less

Saturn's F Ring Core: Calm in the Midst of Chaos

NASA Technical Reports Server (NTRS)

Cuzzi, J. N.; Whizin, A. D.; Hogan, R. C.; Dobrovolskis, A. R.; Dones, L.; Showalter. M. R.; Colwell, J. E.; Scargle, J. D.

2013-01-01

The long-term stability of the narrow F Ring core has been hard to understand. Instead of acting as "shepherds", Prometheus and Pandora together stir the vast preponderance of the region into a chaotic state, consistent with the orbits of newly discovered objects like S/2004S6. We show how a comb of very narrow radial locations of high stability in semimajor axis is embedded within this otherwise chaotic region. The stability of these semimajor axes relies fundamentally on the unusual combination of rapid apse precession and long synodic period which characterizes the region. This situation allows stable "antiresonances" to fall on or very close to traditional Lindblad resonances which, under more common circumstances, are destabilizing. We present numerical integrations of tens of thousands of test particles over tens of thousands of Prometheus orbits that map out the effect. The stable antiresonance zones are most stable in a subset of the region where Prometheus first-order resonances are least cluttered by Pandora resonances. This region of optimum stability is paradoxically closer to Prometheus than a location more representative of "torque balance", helping explain a longstanding paradox. One stable zone corresponds closely to the currently observed semimajor axis of the F Ring core. While the model helps explain the stability of the narrow F Ring core, it does not explain why the F Ring material all shares a common apse longitude; we speculate that collisional damping at the preferred semimajor axis (not included in the current simulations) may provide that final step. Essentially, we find that the F Ring core is not confined by a combination of Prometheus and Pandora, but a combination of Prometheus and precession.

Organization of the 1999 Integrated Photonics Research Topical Meeting Held at Fess Parker’s Doubletree Resort, Santa Barbara, California on 19-21 Jul 1999

DTIC Science & Technology

2000-02-29

ArF laser of 6.4eV as photon energy. The irradiation was carried out with an energy density of 100mJ/cm2 per pulse and a pulse repetition of 10...soliton lasers , optical ring memories, femtosecond stretched- pulse lasers , and nonlinear loop filters will be described, (p. 2) 9:00am (Plenary) RMA2...stretched- pulse lasers , and nonlinear loop filters will be described. RMA2-1 / 3 Challenges and opportunities in Photonic Integration M.K. Smit

Synthesis and antisense properties of fluoro cyclohexenyl nucleic acid (F-CeNA), a nuclease stable mimic of 2'-fluoro RNA.

PubMed

Seth, Punit P; Yu, Jinghua; Jazayeri, Ali; Pallan, Pradeep S; Allerson, Charles R; Østergaard, Michael E; Liu, Fengwu; Herdewijn, Piet; Egli, Martin; Swayze, Eric E

2012-06-01

We report the design and synthesis of 2'-fluoro cyclohexenyl nucleic acid (F-CeNA) pyrimidine phosphoramidites and the synthesis and biophysical, structural, and biological evaluation of modified oligonucleotides. The synthesis of the nucleoside phosphoramidites was accomplished in multigram quantities starting from commercially available methyl-D-mannose pyranoside. Installation of the fluorine atom was accomplished using nonafluorobutanesulfonyl fluoride, and the cyclohexenyl ring system was assembled by means of a palladium-catalyzed Ferrier rearrangement. Installation of the nucleobase was carried out under Mitsunobu conditions followed by standard protecting group manipulations to provide the desired pyrimidine phosphoramidites. Biophysical evaluation indicated that F-CeNA shows behavior similar to that of a 2'-modified nucleotide, and duplexes with RNA showed slightly lower duplex thermostability as compared to that of the more rigid 3'-fluoro hexitol nucleic acid (FHNA). However, F-CeNA modified oligonucleotides were significantly more stable against digestion by snake venom phosphodiesterases (SVPD) as compared to unmodified DNA, 2'-fluoro RNA (FRNA), 2'-methoxyethyl RNA (MOE), and FHNA modified oligonucleotides. Examination of crystal structures of a modified DNA heptamer duplex d(GCG)-T*-d(GCG):d(CGCACGC) by X-ray crystallography indicated that the cyclohexenyl ring system exhibits both the (3)H(2) and (2)H(3) conformations, similar to the C3'-endo/C2'-endo conformation equilibrium seen in natural furanose nucleosides. In the (2)H(3) conformation, the equatorial fluorine engages in a relatively close contact with C8 (2.94 Å) of the 3'-adjacent dG nucleotide that may represent a pseudo hydrogen bond. In contrast, the cyclohexenyl ring of F-CeNA was found to exist exclusively in the (3)H(2) (C3'-endo like) conformation in the crystal structure of the modified A-form DNA decamer duplex [d(GCGTA)-T*-d(ACGC)](2.) In an animal experiment, a 16-mer F-CeNA gapmer ASO showed similar RNA affinity but significantly improved activity compared to that of a sequence matched MOE ASO, thus establishing F-CeNA as a useful modification for antisense applications.

STATUS REPORT FOR AGING STUDIES OF EPDM O-RING MATERIAL FOR THE H1616 SHIPPING PACKAGE

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

Stefek, T.; Daugherty, W.; Skidmore, E.

This is an interim status report for tasks carried out per Task Technical Plan SRNL-STI-2011-00506. A series of tasks/experiments are being performed at the Savannah River National Laboratory to monitor the aging performance of ethylene propylene diene monomer (EPDM) Orings used in the H1616 shipping package. The data will support the technical basis to extend the annual maintenance of the EPDM O-rings in the H1616 shipping package and to predict the life of the seals at bounding service conditions. Current expectations are that the O-rings will maintain a seal at bounding normal temperatures in service (152 F) for at leastmore » 12 months. The baseline aging data review suggests that the EPDM O-rings are likely to retain significant mechanical properties and sealing force at bounding service temperatures to provide a service life of at least 2 years. At lower, more realistic temperatures, longer service life is likely. Parallel compression stress relaxation and vessel leak test efforts are in progress to further validate this assessment and quantify a more realistic service life prediction. The H1616 shipping package O-rings were evaluated for baseline property data as part of this test program. This was done to provide a basis for comparison of changes in material properties and performance parameters as a function of aging. This initial characterization was limited to physical and mechanical properties, namely hardness, thickness and tensile strength. These properties appear to be consistent with O-ring specifications. Three H1616-1 Containment Vessels were placed in test conditions and are aging at temperatures ranging from 160 to 300 F. The vessels were Helium leak-tested initially and have been tested at periodic intervals after cooling to room temperature to determine if they meet the criterion of leaktightness defined in ANSI standard N14.5-97 (< 1E-07 std cc air/sec at room temperature). To date, no leak test failures have occurred. The cumulative time at temperature ranges from 174 days for the 300 F vessel to 189 days for the 160 F vessel as of 8/1/2012. The compression stress-relaxation (CSR) behavior of H1616 shipping package O-rings is being evaluated to develop an aging model based on material properties. O-ring segments were initially aged at four temperatures (175 F, 235 F, 300 F and 350 F). These temperatures were selected to bound normal service temperatures and to challenge the seals within a reasonable aging period. Currently, samples aging at 300 F and 350 F have reached the mechanical failure point (end of life) which is defined in this study as 90% loss of initial sealing force. As a result, additional samples more recently began aging at {approx}270 F to provide additional data for the aging model. Aging and periodic leak testing of the full containment vessels, as well as CSR testing of O-ring segments is ongoing. Continued testing per the Task Technical Plan is recommended in order to validate the assumptions outlined in this status report and to quantify and validate the long-term performance of O-ring seals under actual service conditions.« less

Exacerbating Effects of Human Parvovirus B19 NS1 on Liver Fibrosis in NZB/W F1 Mice

PubMed Central

Hsu, Tsai-Ching; Tsai, Chun-Chou; Chiu, Chun-Ching; Hsu, Jeng-Dong; Tzang, Bor-Show

2013-01-01

Systemic lupus erythematosus (SLE) is an autoimmune disorder with unknown etiology that impacts various organs including liver. Recently, human parvovirus B19 (B19) is recognized to exacerbate SLE. However, the effects of B19 on liver in SLE are still unclear. Herein we aimed to investigate the effects of B19 on liver in NZB/W F1 mice by injecting subcutaneously with PBS, recombinant B19 NS1, VP1u or VP2, respectively. Our experimental results revealed that B19 NS1 protein significantly enhanced the TGF-β/Smad fibrotic signaling by increasing the expressions of TGF-β, Smad2/3, phosphorylated Smad2/3, Smad4 and Sp1. The consequent fibrosis-related proteins, PAI-1 and α-SMA, were also significantly induced in livers of NZB/W F1 mice receiving B19 NS1 protein. Accordingly, markedly increased collagen deposition was also observed in livers of NZB/W F1 mice receiving B19 NS1 protein. However, no significant difference was observed in livers of NZB/W F1 mice receiving B19 VP1u or VP2 as compared to the controls. These findings indicate that B19 NS1 plays a crucial role in exacerbating liver fibrosis in NZB/W F1 mice through enhancing the TGF-â/Smad fibrotic signaling. PMID:23840852

Experimental study of electrochemical fluorination of trichloroethylene

NASA Technical Reports Server (NTRS)

Polisena, C.; Liu, C. C.; Savinell, R. F.

1982-01-01

The electrochemical fluorination of trichloroethylene in anhydrous hydrogen fluoride at 0 C and at constant cell potential was investigated. A microprocessor-aided electrochemical fluorination reactor system that yields highly reproducible results was utilized. The following major two-carbon-chain products were observed: CHCl2-CCl2F, CHCl2-CClF2, CHClF-CCl2F, and CCl2F-CClF2. The first step in the reaction sequence was determined to be fluorine addition to the double bond, followed by replacement of first hydrogen and then chlorine by fluorine. Polymerization reactions yielded higher molecular weight or possible ring-type chlorofluorohydrocarbons. A comparison of the reaction products of electrochemical and chemical fluorinations of trichloroethylene is also discussed.

trans-Bis(hexafluoroantimonato)(phthalocyaninato)copper(II).

PubMed

Gardberg, A S; Ibers, J A

2001-05-01

The title compound, trans-bis(hexafluoroantimonato-F)(phthalocyaninato-kappa(4)N(29,30,31,32))copper(II), [Cu(SbF(6))(2)(C(32)H(16)N(8))] or Cu(pc)(SbF(6))(2) (pc is phthalocyaninate), comprises a six-coordinate Cu atom, lying on an inversion center, bonded to four N atoms of a phthalocyanine ring and to F atoms of two trans SbF(6)(-) groups. The compound is presumed to consist of a Cu(II) center and a doubly oxidized phthalocyanine ring, by analogy with Cu(pc)(ReO(4))(2).

EASY: a simple tool for simultaneously removing background, deadtime and acoustic ringing in quantitative NMR spectroscopy--part I: basic principle and applications.

PubMed

Jaeger, Christian; Hemmann, Felix

2014-01-01

Elimination of Artifacts in NMR SpectroscopY (EASY) is a simple but very effective tool to remove simultaneously any real NMR probe background signal, any spectral distortions due to deadtime ringdown effects and -specifically- severe acoustic ringing artifacts in NMR spectra of low-gamma nuclei. EASY enables and maintains quantitative NMR (qNMR) as only a single pulse (preferably 90°) is used for data acquisition. After the acquisition of the first scan (it contains the wanted NMR signal and the background/deadtime/ringing artifacts) the same experiment is repeated immediately afterwards before the T1 waiting delay. This second scan contains only the background/deadtime/ringing parts. Hence, the simple difference of both yields clean NMR line shapes free of artefacts. In this Part I various examples for complete (1)H, (11)B, (13)C, (19)F probe background removal due to construction parts of the NMR probes are presented. Furthermore, (25)Mg EASY of Mg(OH)2 is presented and this example shows how extremely strong acoustic ringing can be suppressed (more than a factor of 200) such that phase and baseline correction for spectra acquired with a single pulse is no longer a problem. EASY is also a step towards deadtime-free data acquisition as these effects are also canceled completely. EASY can be combined with any other NMR experiment, including 2D NMR, if baseline distortions are a big problem. © 2013 Published by Elsevier Inc.

Synthesis of Intrinsically Disordered Fluorinated Peptides for Modular Design of High-Signal 19 F MRI Agents.

PubMed

Kirberger, Steven E; Maltseva, Sofia D; Manulik, Joseph C; Einstein, Samuel A; Weegman, Bradley P; Garwood, Michael; Pomerantz, William C K

2017-06-01

19 F MRI is valuable for in vivo imaging due to the only trace amounts of fluorine in biological systems. Because of the low sensitivity of MRI however, designing new fluorochemicals remains a significant challenge for achieving sufficient 19 F signal. Here, we describe a new class of high-signal, water-soluble fluorochemicals as 19 F MRI imaging agents. A polyamide backbone is used for tuning the proteolytic stability to avoid retention within the body, which is a limitation of current state-of-the-art perfluorochemicals. We show that unstructured peptides containing alternating N-ϵ-trifluoroacetyllysine and lysine provide a degenerate 19 F NMR signal. 19 F MRI phantom images provide sufficient contrast at micromolar concentrations, showing promise for eventual clinical applications. Finally, the degenerate high signal characteristics were retained when conjugated to a large protein, indicating potential for in vivo targeting applications, including molecular imaging and cell tracking. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Saturn's Internal Structure: A View through its Natural Seismograph

NASA Astrophysics Data System (ADS)

Mankovich, Christopher; Marley, Mark S.; Fortney, Jonathan J.; Movshovitz, Naor

2017-10-01

Saturn's nonradial oscillations perturb the orbits of ring particles. The C ring is fortuitous in that it spans several resonances with Saturn's fundamental acoustic (f-) modes, and its moderate optical depth allows the characterization of wave features using stellar occultations. The growing set of C-ring waves with precise pattern frequencies and azimuthal order m measured from Cassini stellar occultations (Hedman & Nicholson 2013, 2014; French et al. 2016) provides new constraints on Saturn's internal structure, with the potential to resolve long-standing questions about the planet's distribution of helium and heavier elements, its means of internal energy transport, and its rotation state.We construct Saturn interior models and calculate mode eigenfrequencies, mapping the planet mode frequencies to resonant locations in the rings to compare with the locations of observed spiral density and vertical bending waves in the C ring. While spiral density waves at low azimuthal order (m=2-3) appear strongly affected by resonant coupling between f-modes and deep g-modes (Fuller 2014), the locations of waves with higher azimuthal order can be fit reasonably well with a spectrum of pure f-modes for Saturn models with adiabatic envelopes and realistic equations of state. In particular, four observed bending waves (Nicholson et al., DPS 2016) align with outer vertical resonances for non-sectoral (m≠l) Saturn f-modes of relatively high angular degree, and we present preliminary identifications of these. We assess the range of resonance locations in the C and D rings allowed for the spectrum of f-modes given gravity field constraints and discuss what role a realistic helium distribution in the planet might play.

Enceladus Races Onward

NASA Image and Video Library

2006-04-05

s our robotic emissary to Saturn, the Cassini spacecraft is privileged to behold such fantastic sights as this pairing of two moons beyond the rings. The bright, narrow F ring is the outermost ring structure seen here

Cassini Radio Occultations of Saturn's Rings: Scattered Signal and Particle Sizes

NASA Astrophysics Data System (ADS)

Thomson, F.; Wong, K.; Marouf, E.; French, R.; Rappaport, N.; McGhee, C.; Anabtawi, A.; Asmar, S.; Barbinis, E.; Fleischman, D.; Goltz, G.; Johnston, D.; Rochblatt, D.

2005-08-01

Eight Cassini radio occultations of Saturn's rings were conducted from May 3 to September 5, 2005. During any given occultation, Cassini transmits Ka-, X-, and S-band sinusoidal signals (0.94, 3.6, and 13 cm-wavelength) through the rings. Spectral analysis of the perturbed signals received at stations of the Deep Space Network (DSN) reveals two distinct signal components. The first is the direct signal, a narrowband component representing the incident sinusoid emerging from the rings reduced in amplitude and changed in phase. The second is the scattered signal, a broadband component, representing near-forward scattering by ring particles. After reconstruction to remove diffraction effects, time history of the direct signal yields profiles of ring structure at resolution approaching ˜50 m. Of primary concern here is the broadband component. For the first time ever, clearly detectable scattered signals were observed at all three (Ka/X/S) bands. A single X/S radio occultation by Voyager 1 in 1980 detected scattered signal at X-band only, primarily because of the small ring opening angle B=5.9o at the time, compared with 19.1 ≤ B ≤ 23.6o for Cassini. Time histories of the observed spectra (spectrograms) and their dependence on wavelength provide important information about physical ring properties, including abundance of meter-size particles, particle crowding, clustering, spatial anisotropy, vertical ring profile and thickness. Cassini occultation orbits were optimized to map scattering by individual ring features into nearly non-overlapping spectral bands, allowing unambiguous identification of the contribution of ring features to the computed spectrograms. We present Ka/X/S spectrograms over the full extent of the ring system and relate their behavior to observed ring structure. The spectrograms imply presence of meters-size particles throughout the ring system. Preliminary results regarding the particle size distribution and vertical ring profile of selected ring features are presented. Contributions of personnel of the DSN are gratefully acknowledged.

Selective cognitive impairment and tall stature due to chromosome 19 supernumerary ring.

PubMed

Melis, Daniela; Genesio, Rita; Del Giudice, Ennio; Taurisano, Roberta; Mormile, Angela; D'Elia, Federica; Conti, Anna; Imperati, Floriana; Andria, Generoso; Nitsch, Lucio

2012-01-01

Small supernumerary marker chromosomes (sSMC) occur with a frequency of approximately 0.4 per 1000 newborns and are more frequent in the population with mental retardation and/or with dysmorphic signs. Small supernumerary chromosome rings (sSCR) usually occur as apart of a mosaic karyotype (Liehr et al., 2004). Chromosome 19 supernumerary rings are very rare. Almost all cases of sSMC19 have been reported on Thomas Liehr's website (http://www.med.uni-jena.de/fish/sSMC/19.htm#Start19). Of these cases, 14 were with phenotypic abnormalities and a clear characterization of the sSMC; two cases were suitable for comparison with our case with regard to their genetic content, but not with regard to the structure ofthe sSMC (Manvelyan et al., 2008). The phenotype, associated with partial trisomy 19q, includes facial dysmorphism, growth and mental retardation, macrocephaly, heart malformation and anomalies of the genitourinary and gastrointestinal tracts. The phenotype associated with partial trisomy 19p is characterized by dysmorphic features, severe mental retardation, abnormalities of brain morphology and anomalies of the fingers (Tercanli et al., 2000; Qorri et al., 2002; Novelli et al., 2005; Vraneković et al., 2008). Herein, we report the phenotype and molecular cytogenetic analysis in a patient with the smallest de-novo constitutional ring extended from the p12 to q12 region of chromosome 19.

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

Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp; Okumura, Satoshi; Komori, Masataka

We developed a prototype positron emission tomography (PET) system based on a new concept called Open-close PET, which has two modes: open and close-modes. In the open-mode, the detector ring is separated into two halved rings and subject is imaged with the open space and projection image is formed. In the close-mode, the detector ring is closed to be a regular circular ring, and the subject can be imaged without an open space, and so reconstructed images can be made without artifacts. The block detector of the Open-close PET system consists of two scintillator blocks that use two types ofmore » gadolinium orthosilicate (GSO) scintillators with different decay times, angled optical fiber-based image guides, and a flat panel photomultiplier tube. The GSO pixel size was 1.6 × 2.4 × 7 mm and 8 mm for fast (35 ns) and slow (60 ns) GSOs, respectively. These GSOs were arranged into an 11 × 15 matrix and optically coupled in the depth direction to form a depth-of-interaction detector. The angled optical fiber-based image guides were used to arrange the two scintillator blocks at 22.5° so that they can be arranged in a hexadecagonal shape with eight block detectors to simplify the reconstruction algorithm. The detector ring was divided into two halves to realize the open-mode and set on a mechanical stand with which the distance between the two parts can be manually changed. The spatial resolution in the close-mode was 2.4-mm FWHM, and the sensitivity was 1.7% at the center of the field-of-view. In both the close- and open-modes, we made sagittal (y-z plane) projection images between the two halved detector rings. We obtained reconstructed and projection images of {sup 18}F-NaF rat studies and proton-irradiated phantom images. These results indicate that our developed Open-close PET is useful for some applications such as proton therapy as well as other applications such as molecular imaging.« less

Moon Convention

NASA Image and Video Library

2015-03-23

People with similar jobs or interests hold conventions and meetings, so why shouldn't moons? Pandora, Prometheus, and Pan -- seen here, from right to left -- also appear to be holding some sort of convention in this image. Some moons control the structure of nearby rings via gravitational "tugs." The cumulative effect of the moon's tugs on the ring particles can keep the rings' edges from spreading out as they are naturally inclined to do, much like shepherds control their flock. Pan is a prototypical shepherding moon, shaping and controlling the locations of the inner and outer edges of the Encke gap through a mechanism suggested in 1978 to explain the narrow Uranian rings. However, though Prometheus and Pandora have historically been called "the F ring shepherd moons" due to their close proximity to the ring, it has long been known that the standard shepherding mechanism that works so well for Pan does not apply to these two moons. The mechanism for keeping the F ring narrow, and the roles played -- if at all -- by Prometheus and Pandora in the F ring's configuration are not well understood. This is an ongoing topic for study by Cassini scientists. This view looks toward the sunlit side of the rings from about 29 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 2, 2015. The view was obtained at a distance of approximately 1.6 million miles (2.6 million kilometers) from the rings and at a Sun-ring-spacecraft, or phase, angle of 86 degrees. Image scale is 10 miles (15 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/pia18306

Development of a prototype Open-close positron emission tomography system

NASA Astrophysics Data System (ADS)

Yamamoto, Seiichi; Okumura, Satoshi; Watabe, Tadashi; Ikeda, Hayato; Kanai, Yasukazu; Toshito, Toshiyuki; Komori, Masataka; Ogata, Yoshimune; Kato, Katsuhiko; Hatazawa, Jun

2015-08-01

We developed a prototype positron emission tomography (PET) system based on a new concept called Open-close PET, which has two modes: open and close-modes. In the open-mode, the detector ring is separated into two halved rings and subject is imaged with the open space and projection image is formed. In the close-mode, the detector ring is closed to be a regular circular ring, and the subject can be imaged without an open space, and so reconstructed images can be made without artifacts. The block detector of the Open-close PET system consists of two scintillator blocks that use two types of gadolinium orthosilicate (GSO) scintillators with different decay times, angled optical fiber-based image guides, and a flat panel photomultiplier tube. The GSO pixel size was 1.6 × 2.4 × 7 mm and 8 mm for fast (35 ns) and slow (60 ns) GSOs, respectively. These GSOs were arranged into an 11 × 15 matrix and optically coupled in the depth direction to form a depth-of-interaction detector. The angled optical fiber-based image guides were used to arrange the two scintillator blocks at 22.5° so that they can be arranged in a hexadecagonal shape with eight block detectors to simplify the reconstruction algorithm. The detector ring was divided into two halves to realize the open-mode and set on a mechanical stand with which the distance between the two parts can be manually changed. The spatial resolution in the close-mode was 2.4-mm FWHM, and the sensitivity was 1.7% at the center of the field-of-view. In both the close- and open-modes, we made sagittal (y-z plane) projection images between the two halved detector rings. We obtained reconstructed and projection images of 18F-NaF rat studies and proton-irradiated phantom images. These results indicate that our developed Open-close PET is useful for some applications such as proton therapy as well as other applications such as molecular imaging.

HST observations of Chiron: preliminary results

NASA Astrophysics Data System (ADS)

BENEDETTI Rossi, Gustavo; Sicardy, Bruno; Buie, Marc W.; Braga-Ribas, Felipe; Ortiz, Jose-Luis; Duffard, Rene; camargo, julio; Vieira-Martins, Roberto; Gratadour, Damien; Dumas, Christophe

2016-10-01

Chiron is a Centaur object, with a radius of approximately 110km. It is orbiting between Saturn and Uranus, and may be a Transneptunian Object (TNO) that has been recently (less than 10 My) scattered by gravitational perturbations from Uranus, just like its "twin brother" Chariklo. On June 3rd, 2013, a stellar occultation by Chariklo of a R=12.4 magnitude star was observed from seven sites in South America, which led to the detection of a total of twelve secondary events, revealing the presence of two narrow and dense rings (see more details at Braga-Ribas F. et al., Nature, 2014).Up to now, planetary rings have been detected exclusively around the four giant planets of our Solar System and Chariklo. In spite of hundreds of occultations by asteroids and several space missions, no other small bodies have shown the presence of rings. However, two recent papers (Ruprecht et al. 2015 and Ortiz et. al 2015) report secondary events from stellar occultations by Chiron that have been interpreted either as a dust shell or a ring system. Using the Hubble Space Telescope we obtained direct images of Chiron surroundings to search for rings, jets and/or small satellites. First results will be presented.

Subunit rotation of ATP synthase embedded in membranes: a or β subunit rotation relative to the c subunit ring

PubMed Central

Nishio, Kazuaki; Iwamoto-Kihara, Atsuko; Yamamoto, Akitsugu; Wada, Yoh; Futai, Masamitsu

2002-01-01

ATP synthase FoF1 (α3β3γδɛab2c10–14) couples an electrochemical proton gradient and a chemical reaction through the rotation of its subunit assembly. In this study, we engineered FoF1 to examine the rotation of the catalytic F1 β or membrane sector Fo a subunit when the Fo c subunit ring was immobilized; a biotin-tag was introduced onto the β or a subunit, and a His-tag onto the c subunit ring. Membrane fragments were obtained from Escherichia coli cells carrying the recombinant plasmid for the engineered FoF1 and were immobilized on a glass surface. An actin filament connected to the β or a subunit rotated counterclockwise on the addition of ATP, and generated essentially the same torque as one connected to the c ring of FoF1 immobilized through a His-tag linked to the α or β subunit. These results established that the γɛc10–14 and α3β3δab2 complexes are mechanical units of the membrane-embedded enzyme involved in rotational catalysis. PMID:12357031

Defense Infrastructure: DOD Should Improve Reporting and Communication on Its Corrosion Prevention and Control Activities

DTIC Science & Technology

2013-05-01

Cycle Prediction for Equipment and Facilities 33.1 33.1 12 FAR16 Corrosion Prevention of Rebar in Concrete in Critical Facilities Located in Coastal...through 2007. 16 N-F-229 Integrated Concrete Pier Piling Repair and Corrosion Protection System 1.9 1.9 2006 17 FNV01 Corrosion Protection...Protection System 3.4 3.0 2007 21 F07NV03 Corrosion Inhibitor Evaluation for Concrete Repairs 16.8 16.8 22 F07NV04 Satellite Based Remote Monitoring

Crystal structure of (7-methyl-2-oxo-2H-chromen-4-yl)methyl piperidine-1-carbo­di­thio­ate

PubMed Central

Roopashree, K. R.; Meenakshi, T. G.; Kumar, K. Mahesh; Kotresh, O.; Devarajegowda, H. C.

2015-01-01

In the title compound, C17H19NO2S2, the 2H-chromene ring system is nearly planar, with a maximum deviation of 0.0383 (28) Å, and the piperidine ring adopts a chair conformation. The 2H-chromene ring makes dihedral angles of 32.89 (16) and 67.33 (8)°, respectively, with the mean planes of the piperidine ring and the carbodi­thio­ate group. In the crystal, C—H⋯O and weak C—H⋯S hydrogen bonds link the mol­ecules into chains along [001]. The crystal structure also features C—H⋯π and π–π inter­actions, with a centroid–centroid distance of 3.7097 (17) Å. PMID:26396821

Planetary science: Shepherds of Saturn's ring

NASA Astrophysics Data System (ADS)

Crida, Aurélien

2015-09-01

Saturn's F ring is chaperoned on both sides by the tiny moons Prometheus and Pandora. Numerical simulations show that this celestial ballet can result from the collision of two aggregates that evolved out of Saturn's main rings.

Natural bond orbital approach to the transmission of substituent effect through the fulvene and benzene ring systems.

PubMed

Oziminski, Wojciech P; Krygowski, Tadeusz M

2011-03-01

Electronic structure of 22 monosubstituted derivatives of benzene and exocyclically substituted fulvene with substituents: B(OH)(2), BH(2), CCH, CF(3), CH(3), CHCH(2), CHO, Cl, CMe(3), CN, COCH(3), CONH(2), COOH, F, NH(2), NMe(2), NO, NO(2), OCH(3), OH, SiH(3), SiMe(3) were studied theoretically by means of Natural Bond Orbital analysis. It is shown, that sum of π-electron population of carbon atoms of the fulvene and benzene rings, pEDA(F) and pEDA(B), respectively correlate well with Hammett substituent constants [Formula in text] and aromaticity index NICS. The substituent effect acting on pi-electron occupation at carbon atoms of the fulvene ring is significantly stronger than in the case of benzene. Electron occupations of ring carbon atoms (except C1) in fulvene plotted against each other give linear regressions with high correlation coefficients. The same is true for ortho- and para-carbon atoms in benzene. Positive slopes of the regressions indicate similar for fulvene and benzene kind of substituent effect - mostly resonance in nature. Only the regressions of occupation at the carbon atom in meta- position of benzene against ortho- and para-positions gives negative slopes and low correlation coefficients.

(2E)-1-(2,6-Dichloro-3-fluoro-phen-yl)-3-phenyl-prop-2-en-1-one.

PubMed

Praveen, Aletti S; Yathirajan, Hemmige S; Narayana, Badiadka; Gerber, Thomas; Hosten, Eric; Betz, Richard

2012-04-01

In the title compound, C(15)H(9)Cl(2)FO, the F atom shows positional disorder over two positions, with site-occupancy factors of 0.747 (4) and 0.253 (4). The dihedral angle between the rings is 86.37 (10)°. In the crystal, C-H⋯O contacts connect the mol-ecules into chains along the c axis. The shortest inter-centroid distance between two aromatic systems is 3.6686 (12) Å and is apparent between the halogenated rings.

The recent formation of Saturn's moonlets from viscous spreading of the main rings.

PubMed

Charnoz, Sébastien; Salmon, Julien; Crida, Aurélien

2010-06-10

The regular satellites of the giant planets are believed to have finished their accretion concurrent with the planets, about 4.5 Gyr ago. A population of Saturn's small moons orbiting just outside the main rings are dynamically young (less than 10(7) yr old), which is inconsistent with the formation timescale for the regular satellites. They are also underdense ( approximately 600 kg m(-3)) and show spectral characteristics similar to those of the main rings. It has been suggested that they accreted at the rings' edge, but hitherto it has been impossible to model the formation process fully owing to a lack of computational power. Here we report a hybrid simulation in which the viscous spreading of Saturn's rings beyond the Roche limit (the distance beyond which the rings are gravitationally unstable) gives rise to the small moons. The moonlets' mass distribution and orbital architecture are reproduced. The current confinement of the main rings and the existence of the dusty F ring are shown to be direct consequences of the coupling of viscous evolution and satellite formation. Saturn's rings, like a mini protoplanetary disk, may be the last place where accretion was recently active in the Solar System, some 10(6)-10(7) yr ago.

19F NMR studies provide insights into lipid membrane interactions of listeriolysin O, a pore forming toxin from Listeria monocytogenes.

PubMed

Kozorog, Mirijam; Sani, Marc-Antoine; Lenarčič Živković, Martina; Ilc, Gregor; Hodnik, Vesna; Separovic, Frances; Plavec, Janez; Anderluh, Gregor

2018-05-02

Listeria monocytogenes is a mammalian pathogen that causes gastroenteritis, miscarriages and infections of the central nervous system in immunocompromised individuals. Its main virulence factor is listeriolysin O (LLO), a pore-forming cholesterol-dependent cytolysin (CDC), which enables bacterial escape from the phagolysosome and contributes to bacterial pathogenicity. Details of cholesterol (Chol) recognition and membrane binding mechanisms by LLO are still not known. Here we used 19 F-NMR spectroscopy in order to assess LLO-Chol interactions in solution and in a Chol-rich membrane environment. LLO has six tryptophan residues located in the region of the molecule that is first in contact with lipid membranes. 19 F-LLO, which contained 5-fluoro-tryptophans, was prepared by using isotopic labelling in an E. coli expression system. Signals in the 19 F-NMR spectrum of 19 F-LLO were unambiguously assigned by using a series of single Trp → Phe point mutations. The results employing various cholesterol preparations in solution indicate that tryptophan residues are not directly involved in Chol binding in solution. However, significant chemical shift changes were observed upon LLO binding to Chol-rich membranes, highlighting the role of tryptophan residues in membrane interactions (W512) and oligomerisation (W189 and W489).

Electrical Engineering (Selected Articles).

DTIC Science & Technology

1980-05-15

Homopolar Machine with Sodium-Potassium Ring-Shaped Contacts, by L.A. Sukhanov , G.A. Karmonov .......... 19 ACCESSION forWht hieSeto NTISuf ecine 1DOCS...3663 FACE 19 DIFECT-CURRENT HOMOPOLAS AACHIhI ITH SCIIUM-ECIASSIUM RING-SHAPED CONTACTS L. A. Sukhanov , Cand. tech. sciences, G. A. Karmanov, eng. ThA

Synthesis and structures of bis-ligated zinc complexes supported by tridentate ketoimines that initiate L-lactide polymerization.

PubMed

Gerling, Kimberly A; Rezayee, Nomaan M; Rheingold, Arnold L; Green, David B; Fritsch, Joseph M

2014-11-21

Eight bis-ligated, homoleptic, zinc complexes were synthesized through the reaction of NNO Schiff base ketoimines bearing varying substituents with diethyl zinc in an inert atmosphere glovebox at room temperature and isolated in 62-95% yield. The complexes were characterized with (1)H, (13)C, and (19)F nuclear magnetic resonance spectroscopy, absorbance spectroscopy, high resolution mass spectrometry, elemental analysis, and single crystal X-ray crystallography. The complexes were shown to adopt distorted octahedral coordination geometry around zinc. The (1)H and (19)F NMR spectra of complexes 1-7 showed stable zinc coordination at 300 K while the effect of steric encumbrance and two trifluoromethyl groups in complex 8 was investigated with variable temperature NMR. The bis-ligated zinc complexes were effective initiators for the ring opening polymerization of L-lactide into poly-L-lactic acid (PLLA). With [L-lac]/[Zn complex] = 50, the bis-ligated zinc complexes yielded percentage conversion of 14-98% with polymerization times varying from 15-1440 min, where the longest reaction times were required when two trifluoromethyl groups were present. The addition of 4-fluorophenol co-catalyst resulted in up to a 5-fold increase in the percentage conversion in toluene solution and up to a 14-fold increase in bulk melt polymerization with reductions in the poly-dispersity index values for the isolated PLLA. Addition of 4-fluorophenol to complex 1 was studied with (1)H and (19)F NMR and appeared to yield an in situ generated zinc alkoxide complex.

Scattering properties of Saturn's rings in the far ultraviolet from Cassini UVIS spectra

NASA Astrophysics Data System (ADS)

Bradley, E. Todd; Colwell, Joshua E.; Esposito, Larry W.

2013-07-01

We use Cassini UVIS data to determine the scattering properties of Saturn's ring particles in the FUV. We have replaced the scattering function from the classical Chandrasekhar single scattering radiative transfer equation for reflectance with a ring wake model for the A and B rings derived from stellar occultations. The free parameters in this model are the ring particle Bond albedo, AB, and the ring particle asymmetry parameter, g, which equals the cosine of the most probable scattering angle of a photon from a ring particle. The spectrum of Saturn's rings from 140 to 190 nm shows an absorption feature due to water ice shortward of 165 nm. We compare our model values for I/F to lit-side data at 155 nm and at 180 nm for regions in both the A and B rings. We used the unmodified Chandrasekhar model for the C ring and Cassini Division, and in all cases we determined AB and g in the FUV for the first time. Values of AB vary between 0.04 and 0.091 at 180 nm and between 0.012 and 0.019 at 155 nm. The variations across the ring of AB at 180 nm is consistent with a greater abundance of non-ice contaminant in the C ring and Cassini Division and a minimum in contaminant abundance in the outer B ring. There is little variation in AB at 155 nm across the rings, which suggests that the reflectance of the water ice and non-water ice material shortward of the 165 nm absorption edge are about the same. Values of g vary between -0.68 and -0.78 at 180 nm and between -0.63 and -0.77 at 155 nm showing that the ring particles are highly backscattering in the FUV. We find that the wavelength of the absorption feature varies with ring region and viewing geometry indicating a different photon mean path length, L, through the outer layer of the ring particle (Bradley, E.T., Colwell, J.E., Esposito, L.W., Cuzzi, J.N., Tollerud, H., Chambers, L. [2010]. Icarus 206 (2), 458-466). We compared I/F from 152 to 185 nm to a radiative transfer spectral model developed by Shkuratov et al. (Shkuratov, Y., Starukhina, L., Hoffmann, H., Arnold, G. [1999]. Icarus 137, 235-246) and modified by Poulet et al. (Poulet, F., Cuzzi, J.N., Cruikshank, D.P., Roush, T., Dalle Ore, C.M. [2002]. Icarus 160, 313-324). We find that L is positively correlated with phase angle, which we attribute to multiple scattering within the particle on length scales comparable to L. We extrapolate L to zero phase angle and find values of L at zero phase ranging from ˜2 to 3 μm. This provides a direct measure of the distance from the surface of a ring particle to the first scattering center. L at zero phase is roughly constant across the rings suggesting the outermost 1.25 μm of the ring particles have the same structural properties in all ring regions. We azimuthally binned and interpolated observations of the unlit side of the A ring taken during Saturn orbit insertion to a 100 km resolution radial profile. We see halos (enhanced brightness) surrounding the Janus 4:3 and Janus 5:4 density waves. We also computed I/F across the A ring using the SOI observational geometry along with AB and the power-law index, n, derived from the retrieval approach from lit side observations. I/F determined by this technique agrees with results from the lit side analysis for the A2 ring but diverge for the inner and outer A ring, which we attribute to multiple scattering effects.

A Glimpse of Atlas

NASA Technical Reports Server (NTRS)

2005-01-01

Saturn's little moon Atlas orbits Saturn between the outer edge of the A ring and the fascinating, twisted F ring. This image just barely resolves the disk of Atlas, and also shows some of the knotted structure for which the F ring is known. Atlas is 32 kilometers (20 miles) across.

The bright outer edge of the A ring is overexposed here, but farther down the image several bright ring features can be seen.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 25, 2005, at a distance of approximately 2.4 million kilometers (1.5 million miles) from Atlas and at a Sun-Atlas-spacecraft, or phase, angle of 60 degrees. Resolution in the original image was 14 kilometers (9 miles) per pixel.

A View into Saturn through its Natural Seismograph

NASA Astrophysics Data System (ADS)

Mankovich, Christopher

2018-04-01

Saturn's nonradial oscillations perturb the orbits of ring particles. The C ring is fortuitous in that it spans several resonances with Saturn's fundamental acoustic (f-) modes, and its moderate optical depth allows the characterization of wave features using stellar occultations. The growing set of C-ring waves with precise pattern frequencies and azimuthal order m measured from Cassini stellar occultations (Hedman & Nicholson 2013, 2014; French et al. 2016) provides new constraints on Saturn's internal structure, with the potential to aid in resolving long-standing questions about the planet's distribution of helium and heavier elements, its means of internal energy transport, and its rotation state.We construct Saturn interior models and calculate mode eigenfrequencies, mapping the planet mode frequencies to resonant locations in the rings to compare with the locations of observed spiral density and vertical bending waves in the C ring. While spiral density waves at low azimuthal order (m=2-3) appear strongly affected by resonant coupling between f-modes and deep g-modes (Fuller 2014), the locations of waves with higher azimuthal order can be fit with a spectrum of pure f-modes for Saturn models with adiabatic envelopes and realistic equations of state. Notably, several newly observed density waves and bending waves (Nicholson et al., in preparation) align with outer Lindblad and outer vertical resonances for non-sectoral (m!=l) Saturn f-modes of relatively high angular degree, and we present normal mode identifications for these waves. We assess the range of resonance locations in the C and D rings allowed for the spectrum of f-modes given gravity field constraints, point to other resonance locations that should experience strong forcing, and use the full set of observed waves to estimate Saturn's bulk rotation rate.

Space Science

NASA Image and Video Library

1979-02-05

On February 5, 1979, Voyager 1 made its closest approach to Jupiter since early 1974 and 1975 when Pioneers 10 and 11 made their voyages to Jupiter and beyond. Voyager 1 completed its Jupiter encounter in early April, after taking almost 19,000 pictures and recording many other scientific measurements. Although astronomers had studied Jupiter from Earth for several centuries, scientists were surprised by many of Voyager 1 and 2's findings. They now understand that important physical, geological, and atmospheric processes go on that they had never observed from Earth. Discovery of active volcanism on the satellite Io was probably the greatest surprise. It was the first time active volcanoes had been seen on another body in the solar system. Voyager also discovered a ring around Jupiter. Thus Jupiter joins Saturn, Uranus, and Neptune as a ringed planet -- although each ring system is unique and distinct from the others.

N-(Quinolin-8-yl)quinoline-2-carbox­amide

PubMed Central

Li, Yanfeng; Zhou, Hongbo; Shen, Xiaoping

2012-01-01

In the title compound, C19H13N3O, the dihedral angle between the two quinoline systems is 11.54 (3)°. The mol­ecular conformation is stabilized by intra­molecular N—H⋯N and C—H⋯O hydrogen bonds, with N—H⋯N being bifurcated towards the two N atoms of the two quinoline rings. In the crystal, there are weak intermolecular π–π inter­actions present involving the quinoline rings [centroid–centroid distance 3.7351 (14) Å]. PMID:22719482

N-(1-Allyl-3-chloro-4-eth-oxy-1H-indazol-5-yl)-4-methyl-benzene-sulfonamide.

PubMed

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2014-06-01

In the title compound, C19H20ClN3O3S, the benzene ring is inclined to the indazole ring system by 51.23 (8)°. In the crystal, mol-ecules are linked by pairs of N-H⋯O hydrogen bonds, forming inversion dimers which stack in columns parallel to [011]. The atoms in the allyl group are disordered over two sets of sites with an occupancy ratio of 0.624 (8):0.376 (8).

N-(2-Allyl-4-eth-oxy-2H-indazol-5-yl)-4-methyl-benzene-sulfonamide.

PubMed

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Viale, Maurizio; Saadi, Mohamed; El Ammari, Lahcen

2014-05-01

The indazole ring system of the title compound, C19H21N3O3S, is almost planar (r.m.s. deviation = 0.0192 Å) and forms dihedral angles of 77.99 (15) and 83.9 (3)° with the benzene ring and allyl group, respectively. In the crystal, centrosymmetrically related mol-ecules are connected by pairs of N-H⋯O hydrogen bonds into dimers, which are further linked by C-H⋯O hydrogen bonds, forming columns parallel to the b axis.

Novel High Temperature Capacitive Pressure Sensor Utilizing SiC Integrated Circuit Twin Ring Oscillators

NASA Technical Reports Server (NTRS)

Scardelletti, M.; Neudeck, P.; Spry, D.; Meredith, R.; Jordan, J.; Prokop, N.; Krasowski, M.; Beheim, G.; Hunter, G.

2017-01-01

This paper describes initial development and testing of a novel high temperature capacitive pressure sensor system. The pressure sensor system consists of two 4H-SiC 11-stage ring oscillators and a SiCN capacitive pressure sensor. One oscillator has the capacitive pressure sensor fixed at one node in its feedback loop and varies as a function of pressure and temperature while the other provides a pressure-independent reference frequency which can be used to temperature compensate the output of the first oscillator. A two-day repeatability test was performed up to 500C on the oscillators and the oscillator fundamental frequency changed by only 1. The SiCN capacitive pressure sensor was characterized at room temperature from 0 to 300 psi. The sensor had an initial capacitance of 3.76 pF at 0 psi and 1.75 pF at 300 psi corresponding to a 54 change in capacitance. The integrated pressure sensor system was characterized from 0 to 300 psi in steps of 50 psi over a temperature range of 25 to 500C. The pressure sensor system sensitivity was 0.113 kHzpsi at 25C and 0.026 kHzpsi at 500C.

Rho1- and Pkc1-dependent phosphorylation of the F-BAR protein Syp1 contributes to septin ring assembly

PubMed Central

Merlini, Laura; Bolognesi, Alessio; Juanes, Maria Angeles; Vandermoere, Franck; Courtellemont, Thibault; Pascolutti, Roberta; Séveno, Martial; Barral, Yves; Piatti, Simonetta

2015-01-01

In many cell types, septins assemble into filaments and rings at the neck of cellular appendages and/or at the cleavage furrow to help compartmentalize the plasma membrane and support cytokinesis. How septin ring assembly is coordinated with membrane remodeling and controlled by mechanical stress at these sites is unclear. Through a genetic screen, we uncovered an unanticipated link between the conserved Rho1 GTPase and its effector protein kinase C (Pkc1) with septin ring stability in yeast. Both Rho1 and Pkc1 stabilize the septin ring, at least partly through phosphorylation of the membrane-associated F-BAR protein Syp1, which colocalizes asymmetrically with the septin ring at the bud neck. Syp1 is displaced from the bud neck upon Pkc1-dependent phosphorylation at two serines, thereby affecting the rigidity of the new-forming septin ring. We propose that Rho1 and Pkc1 coordinate septin ring assembly with membrane and cell wall remodeling partly by controlling Syp1 residence at the bud neck. PMID:26179915

Use of a marshmallow bolus for evaluating lower esophageal mucosal rings.

PubMed

Ott, D J; Kelley, T F; Chen, M Y; Gelfand, D W; Wu, W C

1991-07-01

Sixty-three patients (35 women, 28 men; mean age 55 yr) with lower esophageal mucosal ring shown radiographically were examined with a semi-solid bolus consisting of a portion of a standard marshmallow. The most common symptom was dysphagia, present in 46 (73%) patients. Impaction of the marshmallow bolus by the ring occurred in 40 (63%) of the 63 patients, and produced symptoms in 27 (68%) of these 40 patients. Nine (14%) rings were detected radiographically only with a solid bolus; eight of these patients had dysphagia and seven rings were 20 mm or less in caliber. Impaction related to ring caliber, and was found in all 17 (100%) rings that were 13 mm or less in diameter, in 17/24 (71%) 14- to 19-mm rings, and in 6/22 (27%) rings 20 mm or more in caliber. Endoscopy in 23 patients detected 16 (70%) rings, and also depended on ring caliber: less than or equal to 13 mm, 6/6 (100%); 14-19 mm, 5/9 (56%); greater than or equal to 20 mm, 5/8 (63%). Marshmallow impaction occurred in 17 (74%) of 23 patients who had endoscopy; three of the 23 patients had normal endoscopy. In conclusion, radiographic examination supplemented by the use of a marshmallow bolus best detects lower esophageal mucosal ring.

Crystal structure and Hirshfield analysis of the 4-(di-methyl-amino)-pyridine adduct of 4-meth-oxy-phenyl-borane.

PubMed

Shooter, Jesse; Allen, Caleb J; Tinsley, Colby W K; Zakharov, Lev N; Abbey, Eric R

2017-11-01

The title compound [systematic name: 4-(di-methyl-amino)-pyridine-4-meth-oxy-phenyl-borane (1/1)], C 14 H 19 BN 2 O, contains two independent mol-ecules in the asymmetric unit. Both molecules exhibit coplanar, mostly sp 2 -hybridized meth-oxy and di-methyl-amino substituents on their respective aromatic rings, consistent with π-donation into the aromatic systems. The B-H groups exhibit an intra-molecular close contact with a C-H group of the pyridine ring, which may be evidence of electrostatic attraction between the hydridic B-H and the electropositive aromatic C-H. There appears to be weak C-H⋯π(arene) inter-actions between two of the H atoms of an amino-methyl group and the meth-oxy-substituted benzene ring of the other independent mol-ecule, and another C-H⋯π (arene) inter-action between one of the pyridine ring H atoms and the same benzene ring.

A Compact Trench-Assisted Multi-Orbital-Angular-Momentum Multi-Ring Fiber for Ultrahigh-Density Space-Division Multiplexing (19 Rings × 22 Modes)

PubMed Central

Li, Shuhui; Wang, Jian

2014-01-01

We present a compact (130 μm cladding diameter) trench-assisted multi-orbital-angular-momentum (OAM) multi-ring fiber with 19 rings each supporting 22 modes with 18 OAM ones. Using the high-contrast-index ring and trench designs, the trench-assisted multi-OAM multi-ring fiber (TA-MOMRF) features both low-level inter-mode crosstalk and inter-ring crosstalk within a wide wavelength range (1520 to 1630 nm), which can potentially enable Pbit/s total transmission capacity and hundreds bit/s/Hz spectral efficiency in a single TA-MOMRF. Moreover, the effective refractive index difference of even and odd fiber eigenmodes induced by the ellipticity of ring and fiber bending and their impacts on the purity of OAM mode and mode coupling/crosstalk are analyzed. It is found that high-order OAM modes show preferable tolerance to the ring ellipticity and fiber bending. The designed fiber offers favorable tolerance to both small ellipticity of ring (<−22 dB crosstalk under an ellipticity of 0.5%) and small bend radius (<−20 dB crosstalk under a bend radius of 2 cm). PMID:24458159

(E)-1-[2-Hy-droxy-4,6-bis-(meth-oxy-meth-oxy)phen-yl]-3-phenyl-prop-2-en-1-one.

PubMed

Niu, Chao; Liu, Y Q; He, Y W; Aisa, H A

2013-05-01

The title compound, C19H20O6, consists of a tetra-substituted benzene ring with one substituent being an α,β-unsaturated cinnamoyl group, which forms an extended conjugated system in the mol-ecule. In addition, two meth-oxy-meth-oxy and one hy-droxy group are bonded to the central benzene ring. The dihedral angle between eh rings is 10.22 (10)°. An intra-molecular hydrogen bond is observed between the hy-droxy group and the carbonyl O atom. One of the meth-oxy-meth-oxy substituents is conformationally disordered over two sets of sites with site-occupation factors of 0.831 (3) and 0.169 (3).

New design of a triplexer using ring resonator integrated with directional coupler based on photonic crystals

NASA Astrophysics Data System (ADS)

Wu, Yaw-Dong; Shih, Tien-Tsorng; Lee, Jian-Jang

2009-11-01

In this paper, we proposed the design of directional coupler integrated with ring resonator based on two-dimensional photonic crystals (2D PCs) to develop a triplexer filter. It can be widely used as the fiber access network element for multiplexer-demultiplexer wavelength selective in fiber-to-the-home (FTTH) communication systems. The directional coupler is chosen to separate the wavelengths of 1490nm and 1310nm. The ring resonator separates the wavelength of 1550nm. The transmission efficiency is larger than 90%. Besides, the total size of propose triplexer is only 19μm×12μm. We present simulation results using the finite-difference time-domain (FDTD) method for the proposed structure.

Crystal structure of N-(1-allyl-3-chloro-4-eth-oxy-1H-indazol-5-yl)-4-meth-oxybenzene-sulfonamide.

PubMed

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2014-09-01

In the title compound, C19H20ClN3O4S, the benzene ring is inclined to the indazole ring system (r.m.s. deviation = 0.014 Å) by 65.07 (8)°. The allyl and eth-oxy groups are almost normal to the indazole ring, as indicated by the respective torsion angles [N-N-C-C = 111.6 (2) and C-C-O-C = -88.1 (2)°]. In the crystal, mol-ecules are connected by N-H⋯N hydrogen bonds, forming helical chains propagating along [010]. The chains are linked by C-H⋯O hydrogen bonds, forming a three-dimensional network.

Ring flips revisited: (13)C relaxation dispersion measurements of aromatic side chain dynamics and activation barriers in basic pancreatic trypsin inhibitor.

PubMed

Weininger, Ulrich; Modig, Kristofer; Akke, Mikael

2014-07-22

Intramolecular motions of proteins are critical for biological function. Transient structural fluctuations underlie a wide range of processes, including enzyme catalysis, ligand binding to buried sites, and generic protein motions, such as 180° rotation of aromatic side chains in the protein interior, but remain poorly understood. Understanding the dynamics and molecular nature of concerted motions requires characterization of their rates and energy barriers. Here we use recently developed (13)C transverse relaxation dispersion methods to improve our current understanding of aromatic ring flips in basic pancreatic trypsin inhibitor (BPTI). We validate these methods by benchmarking ring-flip rates against the three previously characterized cases in BPTI, namely, Y23, Y35, and F45. Further, we measure conformational exchange for one additional aromatic ring, F22, which can be interpreted in terms of a flip rate of 666 s(-1) at 5 °C. Upon inclusion of our previously reported result that Y21 also flips slowly [Weininger, U., et al. (2013) J. Phys. Chem. B 117, 9241-9247], the (13)C relaxation dispersion experiments thus reveal relatively slow ring-flip rates for five of eight aromatic residues in BPTI. These results are in contrast with previous reports, which have estimated that all rings, except Y23, Y35, and F45, flip with a high rate at ambient temperature. The (13)C relaxation dispersion data result in an updated rank order of ring-flip rates in BPTI, which agrees considerably better with that estimated from a recent 1 ms molecular dynamics trajectory than do previously published NMR data. However, significant quantitative differences remain between experiment and simulation, in that the latter yields flip rates that are in many cases too fast by 1-2 orders of magnitude. By measuring flip rates across a temperature range of 5-65 °C, we determined the activation barriers of ring flips for Y23, Y35, and F45. Y23 and F45 have identical activation parameters, suggesting that the fluctuations of the protein core around these residues are similar in character. Y35 differs from the other two in its apparent activation entropy. These results might be rationalized by the fact that Y23 and F45 are located in the same region of the structure while Y35 is remote from the other two rings. As indicated by our new results for the exceptionally well-characterized protein BPTI, (13)C relaxation dispersion experiments open the possibility of studying ring flips in a range of cases wider than that previously possible.

A new role for coenzyme F420 in aflatoxin reduction by soil mycobacteria.

PubMed

Graham, David E

2010-11-01

Hepatotoxic aflatoxins have found a worthy adversary in two new families of bacterial oxidoreductases. These enzymes use the reduced coenzyme F420 to initiate the degradation of furanocoumarin compounds, including the major mycotoxin products of Aspergillus flavus. Along with pyridoxal 5'-phosphate synthases and aryl nitroreductases, these proteins form a large and versatile superfamily of flavin and deazaflavin-dependent oxidoreductases. F420-dependent members of this family appear to share a common mechanism of hydride transfer from the reduced, low-potential deazaflavin to the electron-deficient ring systems of their substrates. © 2010 Blackwell Publishing Ltd.

MicroCommentary: A New Role for Coenzyme F420 in Aflatoxin Reduction by Soil Mycobacteria

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

Graham, David E

Hepatotoxic aflatoxins have found a worthy adversary in two new families of bacterial oxidoreductases. These enzymes use the reduced coenzyme F420 to initiate the degradation of furanocoumarin compounds, including the major mycotoxin products of Aspergillus flavus. Along with pyridoxalamine 5 -phosphate oxidases and aryl nitroreductases, these proteins form a large and versatile superfamily of flavin and deazaflavin-dependent oxidoreductases. F420-dependent members of this family appear to share a common mechanism of hydride transfer from the reduced deazaflavin to the electron-deficient ring systems of their substrates.

Crooked Shadow

NASA Image and Video Library

2009-07-28

The shadow of the moon Mimas strikes the F ring at a different angle than the angle at which it is cast on the A ring, illustrating differences in the vertical heights of the rings in this image taken as Saturn approaches its August 2009 equinox.

First-Principles Prediction of Spin-Polarized Multiple Dirac Rings in Manganese Fluoride

NASA Astrophysics Data System (ADS)

Jiao, Yalong; Ma, Fengxian; Zhang, Chunmei; Bell, John; Sanvito, Stefano; Du, Aijun

2017-07-01

Spin-polarized materials with Dirac features have sparked great scientific interest due to their potential applications in spintronics. But such a type of structure is very rare and none has been fabricated. Here, we investigate the already experimentally synthesized manganese fluoride (MnF3 ) as a novel spin-polarized Dirac material by using first-principles calculations. MnF3 exhibits multiple Dirac cones in one spin orientation, while it behaves like a large gap semiconductor in the other spin channel. The estimated Fermi velocity for each cone is of the same order of magnitude as that in graphene. The 3D band structure further reveals that MnF3 possesses rings of Dirac nodes in the Brillouin zone. Such a spin-polarized multiple Dirac ring feature is reported for the first time in an experimentally realized material. Moreover, similar band dispersions can be also found in other transition metal fluorides (e.g., CoF3 , CrF3 , and FeF3 ). Our results highlight a new interesting single-spin Dirac material with promising applications in spintronics and information technologies.

First-Principles Prediction of Spin-Polarized Multiple Dirac Rings in Manganese Fluoride.

PubMed

Jiao, Yalong; Ma, Fengxian; Zhang, Chunmei; Bell, John; Sanvito, Stefano; Du, Aijun

2017-07-07

Spin-polarized materials with Dirac features have sparked great scientific interest due to their potential applications in spintronics. But such a type of structure is very rare and none has been fabricated. Here, we investigate the already experimentally synthesized manganese fluoride (MnF_{3}) as a novel spin-polarized Dirac material by using first-principles calculations. MnF_{3} exhibits multiple Dirac cones in one spin orientation, while it behaves like a large gap semiconductor in the other spin channel. The estimated Fermi velocity for each cone is of the same order of magnitude as that in graphene. The 3D band structure further reveals that MnF_{3} possesses rings of Dirac nodes in the Brillouin zone. Such a spin-polarized multiple Dirac ring feature is reported for the first time in an experimentally realized material. Moreover, similar band dispersions can be also found in other transition metal fluorides (e.g., CoF_{3}, CrF_{3}, and FeF_{3}). Our results highlight a new interesting single-spin Dirac material with promising applications in spintronics and information technologies.

4,5,7,8,17-Penta­hydr­oxy-14,18-dimethyl-6-methyl­ene-3,10-dioxapenta­cyclo­[9.8.0.01,7.04,19.013,18]nona­dec-14-ene-9,16-dione methanol solvate dihydrate

PubMed Central

Teh, Chin Hoe; Teoh, Siew Chin; Yeap, Chin Sing; Chan, Kit Lam; Fun, Hoong-Kun

2009-01-01

The title quassinoid compound, C20H24O9·CH3OH·2H2O, is a natural eurycomanone isolated from the roots of Eurycoma longifolia. The mol­ecules contain a fused five-ring system, with one tetra­hydro­furan ring adopting an envelope conformation, one tetra­hydro­pyran-2-one ring in a screw boat conformation, one cyclo­hexenone ring in a half-chair conformation and two cyclo­hexane rings in chair conformations. Intra­molecular C—H⋯O inter­actions generate S(5) ring motifs and an O—H⋯O inter­action generates an S(7) ring motif. In the crystal, mol­ecules are linked via inter­molecular O—H⋯O inter­actions along the b axis and further stacked along a axis. The absolute configuration of the title compound was inferred from previously solved structures of its analogues. PMID:21582604

Dynamic localization of HmpF regulates type IV pilus activity and directional motility in the filamentous cyanobacterium Nostoc punctiforme.

PubMed

Cho, Ye Won; Gonzales, Alfonso; Harwood, Thomas V; Huynh, Jessica; Hwang, Yeji; Park, Jun Sang; Trieu, Anthony Q; Italia, Parth; Pallipuram, Vivek K; Risser, Douglas D

2017-10-01

Many cyanobacteria exhibit surface motility powered by type 4 pili (T4P). In the model filamentous cyanobacterium Nostoc punctiforme, the T4P systems are arrayed in static, bipolar rings in each cell. The chemotaxis-like Hmp system is essential for motility and the coordinated polar accumulation of PilA on cells in motile filaments, while the Ptx system controls positive phototaxis. Using transposon mutagenesis, a gene, designated hmpF, was identified as involved in motility. Synteny among filamentous cyanobacteria and the similar expression patterns for hmpF and hmpD imply that HmpF is part of the Hmp system. Deletion of hmpF produced a phenotype distinct from other hmp genes, but indistinguishable from pilB or pilQ. Both an HmpF-GFPuv fusion protein, and PilA, as assessed by in situ immunofluorescence, displayed coordinated, unipolar localization at the leading pole of each cell. Reversals were modulated by changes in light intensity and preceded by the migration of HmpF-GFPuv to the lagging cell poles. These results are consistent with a model where direct interaction between HmpF and the T4P system activates pilus extension, the Hmp system facilitates coordinated polarity of HmpF to establish motility, and the Ptx system modulates HmpF localization to initiate reversals in response to changes in light intensity. © 2017 John Wiley & Sons Ltd.

Dibenzo[a,f]perylene bisimide: effects of introducing two fused rings.

PubMed

Chaolumen; Enno, Hiroki; Murata, Michihisa; Wakamiya, Atsushi; Murata, Yasujiro

2014-11-01

Perylene bisimides (PBIs) are fascinating dyes with various potential applications. To study the effects of introducing a dibenzo-fused structure to the perylene moiety, π-extended PBI derivatives with a dibenzo-fused structure at both of the a and f bonds were synthesized. The twisted structure was characterized by X-ray crystal structure analysis. In the cyclic voltammograms, the dibenzo[a,f]-fused PBI showed a reversible oxidation wave at much less positive potential, relative to a dibenzo[a,o]-fused PBI derivative. These data indicated that two ring fusions at both sides of a naphthalene moiety, which construct a tetracene core, effectively raise the HOMO level compared to fusion of one ring at each naphthalene moiety (two anthracene cores). The dibenzo[a,f]-fused PBI derivative showed an absorption band at 735 nm with a shoulder band reaching 900 nm. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Re-examination of cellular cyclic beta-1,2-glucans of Rhizobiaceae: distribution of ring sizes and degrees of glycerol-1-phosphate substitution.

PubMed

Zevenhuizen, L P; van Veldhuizen, A; Fokkens, R H

1990-04-01

Gel-filtration and thin layer chromatography of low molecular weight carbohydrates from culture filtrates of Agrobacterium radiobacter, Isolate II, have shown, that next to the neutral beta-1,2-glucan fraction a major acidic fraction was present which was found to be glycerophosphorylated cyclic beta-1,2-glucans. Re-examination of cyclic beta-1,2-glucan preparations which had been obtained by extraction of Rhizobium cells with hot phenol-water also showed these acidic modified beta-1,2-glucans to be present. Cyclic beta-1,2-glucans from R. leguminosarum (9 strains) and of R. phaseoli (1 strain) had ring size distribution with degrees of polymerisation (DPs) of 19 and 20 as major ring sizes of which a minor part was glycerophosphorylated; beta-1,2-glucans of R. trifolii (3 strains) had ring sizes with DPs measuring 19-22 as prominent components which were largely unsubstituted, and R. meliloti (7 strains) had beta-1,2-glucans with ring size distributions extending to still higher DPs of 19-25 of which the major part appeared to be glycerophosphorylated.

LOW-ENGINE-FRICTION TECHNOLOGY FOR ADVANCED NATURAL-GAS RECIPROCATING ENGINES

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

Victor W. Wong; Tian Tian; Grant Smedley

2004-09-30

This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston/ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and emissions. An iterative process of simulation, experimentation and analysis, are being followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. To date, a detailed set of piston/ring dynamic and friction models have been developed and applied that illustrated the fundamental relationships between design parameters and friction losses. Various low-friction strategies and ring-design concepts have been explored, and engine experiments have been done on a full-scalemore » Waukesha VGF F18 in-line 6 cylinder power generation engine rated at 370 kW at 1800 rpm. Current accomplishments include designing and testing ring-packs using a subtle top-compression-ring profile (skewed barrel design), lowering the tension of the oil-control ring, employing a negative twist to the scraper ring to control oil consumption. Initial test data indicate that piston ring-pack friction was reduced by 35% by lowering the oil-control ring tension alone, which corresponds to a 1.5% improvement in fuel efficiency. Although small in magnitude, this improvement represents a first step towards anticipated aggregate improvements from other strategies. Other ring-pack design strategies to lower friction have been identified, including reduced axial distance between the top two rings, tilted top-ring groove. Some of these configurations have been tested and some await further evaluation. Colorado State University performed the tests and Waukesha Engine Dresser, Inc. provided technical support. Key elements of the continuing work include optimizing the engine piston design, application of surface and material developments in conjunction with improved lubricant properties, system modeling and analysis, and continued technology demonstration in an actual full-sized reciprocating natural-gas engine.« less

Conductance of closed and open long Aharonov-Bohm-Kondo rings

NASA Astrophysics Data System (ADS)

Shi, Zheng; Komijani, Yashar

2017-02-01

We calculate the finite temperature linear dc conductance of a generic single-impurity Anderson model containing an arbitrary number of Fermi liquid leads, and apply the formalism to closed and open long Aharonov-Bohm-Kondo (ABK) rings. We show that, as with the short ABK ring, there is a contribution to the conductance from the connected four-point Green's function of the conduction electrons. At sufficiently low temperatures this contribution can be eliminated, and the conductance can be expressed as a linear function of the T matrix of the screening channel. For closed rings we show that at temperatures high compared to the Kondo temperature, the conductance behaves differently for temperatures above and below vF/L , where vF is the Fermi velocity and L is the circumference of the ring. For open rings, when the ring arms have both a small transmission and a small reflection, we show from the microscopic model that the ring behaves like a two-path interferometer, and that the Kondo temperature is unaffected by details of the ring. Our findings confirm that ABK rings are potentially useful in the detection of the size of the Kondo screening cloud, the π /2 scattering phase shift from the Kondo singlet, and the suppression of Aharonov-Bohm oscillations due to inelastic scattering.

Haenamindole, an unusual diketopiperazine derivative from a marine-derived Penicillium sp. KCB12F005.

PubMed

Kim, Jong Won; Ko, Sung-Kyun; Son, Sangkeun; Shin, Kee-Sun; Ryoo, In-Ja; Hong, Young-Soo; Oh, Hyuncheol; Hwang, Bang Yeon; Hirota, Hiroshi; Takahashi, Shunji; Kim, Bo Yeon; Osada, Hiroyuki; Jang, Jae-Hyuk; Ahn, Jong Seog

2015-11-15

During the chemical investigation of marine-derived fungus, an unusual diketopiperazine (DKP) alkaloid, haenamindole (1), was isolated from a culture of the marine-derived fungus Penicillium sp. KCB12F005. The structure of 1, which possesses benzyl-hydroxypiperazindione and phenyl-pyrimidoindole rings system in the molecule, was elucidated by analysis of NMR and MS data. The stereochemistry of 1 was determined by ROESY and advanced Marfey's method. Copyright © 2015 Elsevier Ltd. All rights reserved.

Simulation and Micro-Fabrication of Optically Switchable Split Ring Resonators

DTIC Science & Technology

2007-01-01

Simulation and micro-fabrication of optically switchable split ring resonators T.F. Gundogdu a,*, Mutlu Gökkavas b, Kaan Güven b, M. Kafesaki a...mail address: tamara@iesl.forth.gr (T.F. Gundogdu ). 1569-4410/$ – see front matter # 2007 Published by Elsevier B.V. doi:10.1016/j.photonics...ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 T.F. Gundogdu et al. / Photonics and

Planetary Rings

NASA Astrophysics Data System (ADS)

Nicholson, P. D.

2001-11-01

A revolution in the studies in planetary rings studies occurred in the period 1977--1981, with the serendipitous discovery of the narrow, dark rings of Uranus, the first Voyager images of the tenuous jovian ring system, and the many spectacular images returned during the twin Voyager flybys of Saturn. In subsequent years, ground-based stellar occultations, HST observations, and the Voyager flybys of Uranus (1986) and Neptune (1989), as well as a handful of Galileo images, provided much additional information. Along with the completely unsuspected wealth of detail these observations revealed came an unwelcome problem: are the rings ancient or are we privileged to live at a special time in history? The answer to this still-vexing question may lie in the complex gravitational interactions recent studies have revealed between the rings and their retinues of attendant satellites. Among the four known ring systems, we see elegant examples of Lindblad and corotation resonances (first invoked in the context of galactic disks), electromagnetic resonances, spiral density waves and bending waves, narrow ringlets which exhibit internal modes due to collective instabilities, sharp-edged gaps maintained via tidal torques from embedded moonlets, and tenuous dust belts created by meteoroid impact onto parent bodies. Perhaps most puzzling is Saturn's multi-stranded, clumpy F ring, which continues to defy a simple explanation 20 years after it was first glimpsed in grainy images taken by Pioneer 11. Voyager and HST images reveal a complex, probably chaotic, dynamical interaction between unseen parent bodies within this ring and its two shepherd satellites, Pandora and Prometheus. The work described here reflects contributions by Joe Burns, Jeff Cuzzi, Luke Dones, Dick French, Peter Goldreich, Colleen McGhee, Carolyn Porco, Mark Showalter, and Bruno Sicardy, as well as those of the author. This research has been supported by NASA's Planetary Geology and Geophysics program and the Space Telescope Science Institute.

Development of high precision and cryogenic lens holders

NASA Astrophysics Data System (ADS)

Reutlinger, A.; Boesz, Anton; Mottaghibonab, A.; Eckert, P.; Dubowy, M.; Gebler, H.; Grupp, F.; Geis, N.; Bode, A.; Katterloher, R.; Bender, R.

2017-11-01

The optical system of the Near Infrared Spectrometer and Photometer (NISP) of the EUCLID mission consists mainly of a filter and grism wheel and 4 aspherical lenses with large diameters up to 170 mm. The single lenses require a high precision positioning at the operational temperature of 150 K. An additional design driver represents the CaF2 material of a lens, which is very sensitive wrt brittleness. The technical maturity of the combination of single features such as CaF2, large diameter (and mass), high precision and cryogenic conditions is considered as low. Therefore, a dedicated pre-development program has been launched to design and develop a first prototype of lens holder and to demonstrate the functional performance at representative operational conditions. The 4 lenses are divided into 3x lenses for the Camera Lens Assembly (CaLA) and 1x lens for the Corrector Lens Assembly (CoLA). Each lens is glue mounted onto solid state springs, part of an adaption ring. The adaption ring shall provide protection against vibration loads, high accuracy positioning, as well as quasi load free mounting of the lens under operational conditions. To reduce thermomechanical loads on the lens, the CTE of the adaption ring is adapted to that of the lens. The glue between lens and solid state spring has to withstand high tension loads during vibration. At the operational temperature the deviating CTE between glue and lens/adaption ring introduces shear loads into the glue interface, which are critical, in particular for the fragile CaF2 lens material. For the case of NISP the shear loads are controlled with the glue pad diameter and the glue thickness. In the context of the development activity many technology aspects such as various solid state spring designs, glue selection and glue handling have been investigated. A parametric structural model was developed to derive the specific design feature of each ring, such as spring force, number of springs, eigenfrequency, etc. This paper presents the design of the adaption ring in conjunction with test results from functional verification. These results are presented on behalf of the EUCLID consortium.

Fate of polychlorinated dibenzo-p-dioxins and dibenzofurans in a fly ash treatment plant.

PubMed

Li, Hsing-Wang; Wu, Yee-Lin; Lee, Wen-Jhy; Chang-Chien, Guo-Ping

2007-09-01

To understand the fate of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in a fly ash treatment plant that used the Waelz rotary kiln process (hereafter the Waelz process), the samples of input and output media were collected and analyzed. The most important PCDD/F source in input mass was electric arc furnace (EAF) fly ash, which had a mean PCDD/F content of 18.51 ng/g and contributed more than 99% of PCDD/F input mass, whereas the PCDD/F input mass fractions contributed by the coke, sand, and ambient air were only 0.04%, 0.02%, and 0.000002%, respectively. For the PCDD/F output mass in the Waelz process, the major total PCDD/F contents of 43.73 and 10.78 ng/g were in bag-filter and cyclone ashes, which accounted for approximately 69% and 17%, respectively, whereas those of stack flue gas and slag were 14% and 0.423%, respectively. The Waelz process has a dechlorination mechanism for higher chlorinated congeners, but it is difficult to decompose the aromatic rings of PCDD/Fs. Therefore, this resulted in the accumulation of lower chlorinated congeners. The output/input ratio of total PCDD/F mass and total PCDD/F international toxicity equivalence (I-TEQ) was 0.62 and 1.19, respectively. Thus, the Waelz process for the depletion effect of total PCDD/F mass was positive but minor, whereas the effect for total PCDD/F I-TEQ was adverse overall.

Unraveling the strands of Saturn's F ring

USGS Publications Warehouse

Murray, C.D.; Gordon, M.K.; Giuliatti, Winter S.M.

1997-01-01

Several high-resolution Voyager 2 images of Saturn's F ring show that it is composed of at least four separate, non-intersecting strands extending ~45?? in longitude. Voyager 1 images show that the two brightest strands appear to intersect, giving rise to a "braided" morphology. From a study of all available Voyager images the detectable radial structure is cataloged and reviewed. Previous indications that there is fine material interior to the orbit of the F ring are confirmed. Evidence is presented that a model of four strands with comparable eccentricities and nearly aligned perichrones is consistent with all the Voyager observations. The observed perichrone offset of the two brightest strands suggests a minimum radial separation of ~20 km, which implies intersection of these strands when their finite radial widths are taken into account. The longitude range of such an intersection includes that observed in the Voyager 1 "braid" images. The proximity of these two strands at some longitudes may account for the apparent differences in the ring between the Voyager encounters, as well as provide a source for the short-lived features detected in the Hubble Space Telescope images of the F ring. There is no evidence that the locations of the individual strands are determined by resonant perturbations with known satellites. It is proposed that the radial structure is formed by the localized action of small satellites orbiting within the strand region. ?? 1997 Academic Press.

Real-Time Communication Systems: Design, Analysis and Implementation

DTIC Science & Technology

1984-07-31

sively [141-[19). A two-hop configuration involving a ring of repeaters around a station has been analyzed by Gitman [20) ; STATION network capacity...control of the packet-switching broadcast channels," J. Ass. Comput Mach., vol. 24, pp. 375-386, July 1977. [201 I. Gitman , "On the capacity of

LOW-ENGINE-FRICTION TECHNOLOGY FOR ADVANCED NATURAL-GAS RECIPROCATING ENGINES

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

Victor W. Wong; Tian Tian; Grant Smedley

2003-08-28

This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston/ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and emissions. A detailed set of piston/ring dynamic and friction models have been developed and applied that illustrated the fundamental relationships between design parameters and friction losses. Various low-friction strategies and concepts have been explored, and engine experiments will validate these concepts. An iterative process of experimentation, simulation and analysis, will be followed with the goal of demonstrating a complete optimized low-friction engine system. As planned, MIT has developed guidelinesmore » for an initial set of low-friction piston-ring-pack designs. Current recommendations focus on subtle top-piston-ring and oil-control-ring characteristics. A full-scale Waukesha F18 engine has been installed at Colorado State University and testing of the baseline configuration is in progress. Components for the first design iteration are being procured. Subsequent work includes examining the friction and engine performance data and extending the analyses to other areas to evaluate opportunities for further friction improvement and the impact on oil consumption/emission and wear, towards demonstrating an optimized reduced-friction engine system.« less

Algebraic cycles and local anomalies in F-theory

NASA Astrophysics Data System (ADS)

Bies, Martin; Mayrhofer, Christoph; Weigand, Timo

2017-11-01

We introduce a set of identities in the cohomology ring of elliptic fibrations which are equivalent to the cancellation of gauge and mixed gauge-gravitational anomalies in F-theory compactifications to four and six dimensions. The identities consist in (co)homological relations between complex codimension-two cycles. The same set of relations, once evaluated on elliptic Calabi-Yau three-folds and four-folds, is shown to universally govern the structure of anomalies and their Green-Schwarz cancellation in six- and four-dimensional F-theory vacua, respectively. We furthermore conjecture that these relations hold not only within the cohomology ring, but even at the level of the Chow ring, i.e. as relations among codimension-two cycles modulo rational equivalence. We verify this conjecture in non-trivial examples with Abelian and non-Abelian gauge groups factors. Apart from governing the structure of local anomalies, the identities in the Chow ring relate different types of gauge backgrounds on elliptically fibred Calabi-Yau four-folds.

High-Resolution Structure and Mechanism of an F/V-Hybrid Rotor Ring in a Na+-coupled ATP Synthase

PubMed Central

Matthies, Doreen; Zhou, Wenchang; Klyszejko, Adriana L.; Anselmi, Claudio; Yildiz, Özkan; Brandt, Karsten; Müller, Volker; Faraldo-Gómez, José D.; Meier, Thomas

2014-01-01

All rotary ATPases catalyze the interconversion of ATP and ADP-Pi through a mechanism that is coupled to the transmembrane flow of H+ or Na+. Physiologically, however, F/A-type enzymes specialize in ATP synthesis driven by downhill ion diffusion, while eukaryotic V-type ATPases function as ion pumps. To begin to rationalize the molecular basis for this functional differentiation, we solved the crystal structure of the Na+-driven membrane rotor of the Acetobacterium woodii ATP synthase, at 2.1 Å resolution. Unlike known structures, this rotor ring is a 9:1 heteromer of F- and V-type c-subunits, and therefore features a hybrid configuration of ion-binding sites along its circumference. Molecular and kinetic simulations are used to dissect the mechanisms of Na+ recognition and rotation of this c-ring, and to explain the functional implications of the V-type c-subunit. These structural and mechanistic insights indicate an evolutionary path between synthases and pumps involving adaptations in the rotor ring. PMID:25381992

Hardware Description of Mass Weather Dissemination System Exploratory Engineering Model.

DTIC Science & Technology

1982-09-01

TELCO BARGE-IN TLOSSE LOCAL TELCO BARGE-IN i • TELCO SYSTEM EQUIPMENT NORTH ROUTES TELCO BARGE-IN’ ’ RE-I...34 TELCO SYSTEM EQUIPMENT SOUTH/WEST ROUTES 81- FIGURE 1. FUNCTIONAL DESCRIPTION OF THE TRIAL PATWAS OPERATION 2 f . .... " I’, ." The New York City PATWAS...du ring the test for both the old and improved PATWAS systems , and (3) questionnaire data from four questionnaires, one for an initial appraisal

Native structure of a type IV secretion system core complex essential for Legionella pathogenesis.

PubMed

Kubori, Tomoko; Koike, Masafumi; Bui, Xuan Thanh; Higaki, Saori; Aizawa, Shin-Ichi; Nagai, Hiroki

2014-08-12

Bacterial type IV secretion systems are evolutionarily related to conjugation systems and play a pivotal role in infection by delivering numerous virulence factors into host cells. Using transmission electron microscopy, we report the native molecular structure of the core complex of the Dot/Icm type IV secretion system encoded by Legionella pneumophila, an intracellular human pathogen. The biochemically isolated core complex, composed of at least five proteins--DotC, DotD, DotF, DotG, and DotH--has a ring-shaped structure. Intriguingly, morphologically distinct premature complexes are formed in the absence of DotG or DotF. Our data suggest that DotG forms a central channel spanning inner and outer membranes. DotF, a component dispensable for type IV secretion, plays a role in efficient embedment of DotG into the functional core complex. These results highlight a common scheme for the biogenesis of transport machinery.

Voyager Observations of the Color of Saturn's Ring

NASA Technical Reports Server (NTRS)

Estrada, Paul R.; Cuzzi, Jeffrey N.; Morrison, David (Technical Monitor)

1994-01-01

Previously unreduced high resolution Voyager 2 images of Saturn's main rings are used to generate reflectivity (I/F) profiles as a function of radius. Ratios of profiles taken from green, violet, orange, and UV filter images are then produced. The I/F ratios are diagnostic of composition, and provide us with information on the rings' present state of compositional evolution. The rings are extremely reddish in color which suggests that they could not be pure water ice. The most likely candidates for the non-icy components are silicates and organics. The sources of these pollutants are of extreme importance in determining the compositional history of the rings. The radial profiles of ring color ratio exhibit several very interesting properties: (a) broad-scale, fairly smooth, color variations which are only weakly correlated with underlying ring structure (optical depth variations) across the outer C ring and inner B ring as well as the Cassini division region. These variations are probably consistent with ballistic transport; (b) fine-scale, noise-Like (but unquestionably real) color variations across at least the outer two-thirds of the B ring. Not only the "redness" but the spectral shape varies. These variations are currently unexplained. Groundbased spectroscopic observations should be pursued to study the implied compositional heterogeneities on at least the larger scales. This data set will be used for modeling of the color and composition of the main rings using ballistic transport and radiative transfer theories.

Pair Past the Rings

NASA Image and Video Library

2010-03-04

Two of Saturn moons orbit beyond four of the planet rings in this image from NASA Cassini spacecraft. From the top right of the picture are the C, B , A, and thin F rings, the small moon Pandora and, near the middle of the image, the moon Enceladus.

Expanding Actin Rings Zipper the Mouse Embryo for Blastocyst Formation.

PubMed

Zenker, Jennifer; White, Melanie D; Gasnier, Maxime; Alvarez, Yanina D; Lim, Hui Yi Grace; Bissiere, Stephanie; Biro, Maté; Plachta, Nicolas

2018-04-19

Transformation from morula to blastocyst is a defining event of preimplantation embryo development. During this transition, the embryo must establish a paracellular permeability barrier to enable expansion of the blastocyst cavity. Here, using live imaging of mouse embryos, we reveal an actin-zippering mechanism driving this embryo sealing. Preceding blastocyst stage, a cortical F-actin ring assembles at the apical pole of the embryo's outer cells. The ring structure forms when cortical actin flows encounter a network of polar microtubules that exclude F-actin. Unlike stereotypical actin rings, the actin rings of the mouse embryo are not contractile, but instead, they expand to the cell-cell junctions. Here, they couple to the junctions by recruiting and stabilizing adherens and tight junction components. Coupling of the actin rings triggers localized myosin II accumulation, and it initiates a tension-dependent zippering mechanism along the junctions that is required to seal the embryo for blastocyst formation. Copyright © 2018 Elsevier Inc. All rights reserved.

F4+ ETEC infection and oral immunization with F4 fimbriae elicits an IL-17-dominated immune response.

PubMed

Luo, Yu; Van Nguyen, Ut; de la Fe Rodriguez, Pedro Y; Devriendt, Bert; Cox, Eric

2015-10-21

Enterotoxigenic Escherichia coli (ETEC) are an important cause of post-weaning diarrhea (PWD) in piglets. Porcine-specific ETEC strains possess different fimbrial subtypes of which F4 fimbriae are the most frequently associated with ETEC-induced diarrhea in piglets. These F4 fimbriae are potent oral immunogens that induce protective F4-specific IgA antibody secreting cells at intestinal tissues. Recently, T-helper 17 (Th17) cells have been implicated in the protection of the host against extracellular pathogens. However, it remains unknown if Th17 effector responses are needed to clear ETEC infections. In the present study, we aimed to elucidate if ETEC elicits a Th17 response in piglets and if F4 fimbriae trigger a similar response. F4(+) ETEC infection upregulated IL-17A, IL-17F, IL-21 and IL-23p19, but not IL-12 and IFN-γ mRNA expression in the systemic and mucosal immune system. Similarly, oral immunization with F4 fimbriae triggered a Th17 signature evidenced by an upregulated mRNA expression of IL-17F, RORγt, IL-23p19 and IL-21 in the peripheral blood mononuclear cells (PBMCs). Intriguingly, IL-17A mRNA levels were unaltered. To further evaluate this difference between systemic and mucosal immune responses, we assayed the cytokine mRNA profile of F4 fimbriae stimulated PBMCs. F4 fimbriae induced IL-17A, IL-17F, IL-22 and IL-23p19, but downregulated IL-17B mRNA expression. Altogether, these data indicate a Th17 dominated response upon oral immunization with F4 fimbriae and F4(+) ETEC infection. Our work also highlights that IL-17B and IL-17F participate in the immune response to protect the host against F4(+) ETEC infection and could aid in the design of future ETEC vaccines.

Influence of major structural features of tocopherols and tocotrienols on their omega-oxidation by tocopherol-omega-hydroxylase.

PubMed

Sontag, Timothy J; Parker, Robert S

2007-05-01

Human cytochrome P450 4F2 (CYP4F2) catalyzes the initial omega-hydroxylation reaction in the metabolism of tocopherols and tocotrienols to carboxychromanols and is, to date, the only enzyme shown to metabolize vitamin E. The objective of this study was to characterize this activity, particularly the influence of key features of tocochromanol substrate structure. The influence of the number and positions of methyl groups on the chromanol ring, and of stereochemistry and saturation of the side chain, were explored using HepG2 cultures and microsomal reaction systems. Human liver microsomes and microsomes selectively expressing recombinant human CYP4F2 exhibited substrate activity patterns similar to those of HepG2 cells. Although activity was strongly associated with substrate accumulation by cells or microsomes, substantial differences in specific activities between substrates remained under conditions of similar microsomal membrane substrate concentration. Methylation at C5 of the chromanol ring was associated with markedly low activity. Tocotrienols exhibited much higher Vmax values than their tocopherol counterparts. Side chain stereochemistry had no effect on omega-hydroxylation of alpha-tocopherol (alpha-TOH) by any system. Kinetic analysis of microsomal CYP4F2 activity revealed Michaelis-Menten kinetics for alpha-TOH but allosteric cooperativity for other vitamers, especially tocotrienols. Additionally, alpha-TOH was a positive effector of omega-hydroxylation of other vitamers. These results indicate that CYP4F2-mediated tocopherol-omega-hydroxylation is a central feature underlying the different biological half-lives, and therefore biopotencies, of the tocopherols and tocotrienols.

Synthesis of Potential Trypanocides

DTIC Science & Technology

1987-12-01

0188 Ia. REPORT SECURITY CLASSIFICATION 1b RESTRICTIVE MARKINGS Unclassified 2a. SECURITY CLASSIFICATION AUTHORITY 3 . DISTRIBUTION /AVAILABILITY OF...and the phenyl ring, ring structures 2 and 3 , introduction of a -CH:CII- group between the phenyl ring and its 4’-substituent, ring structure 4...imidazole (9, 15) thiazole (11) and pyridine (12-14) into ether-linked and vinyl-linked structures. 3 t % SCHEME 1 HETEROAROMATIC RINGS OHw Ch3 CH3 +1 N% f

Contractile ring stability in S. pombe depends on F-BAR protein Cdc15p and Bgs1p transport from the Golgi complex.

PubMed

Arasada, Rajesh; Pollard, Thomas D

2014-09-11

Cdc15p is known to contribute to cytokinesis in fission yeast; however, the protein is not required to assemble the contractile ring of actin and myosin, but it helps to anchor the ring to the plasma membrane. Cdc15p has a lipid-binding F-BAR domain, suggesting that it provides a physical link between the plasma membrane and contractile ring proteins. However, we find that a more important function of Cdc15p during cytokinesis is to help deliver a transmembrane enzyme, Bgs1p (also called Cps1p), from the Golgi apparatus to the plasma membrane, where it appears to anchor the contractile ring. Bgs1p synthesizes the cell wall in the cleavage furrow, but its enzyme activity is not required to anchor the contractile ring. We estimate that ∼ 2,000 Bgs1p molecules are required to anchor the ring. Without Bgs1p anchors, contractile rings slide along the plasma membrane, a phenomenon that depends on an unconventional type II myosin called Myp2p. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

NMR studies of multiple conformations in complexes of Lactobacillus casei dihydrofolate reductase with analogues of pyrimethamine

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

Birdsall, B.; Tendler, S.J.B.; Feeney, J.

1990-10-01

{sup 1}H and {sup 19}F NMR signals from bound ligands have been assigned in one- and two-dimensional NMR spectra of complexes of Lactobacillus casei dihydrofolate reductase with various pyrimethamine analogues. The signals were identified mainly by correlating signals from bound and free ligands by using 2D exchange experiments. Analogues with symmetrically substituted phenyl rings give rise to {sup 1}H signals from four nonequivalent aromatic protons, clearly indicating the presence of hindered rotation about the pyrimidine-phenyl bond. Analogues with symmetrically substituted phenyl rings give rise to {sup 1}H signals from four nonequivalent aromatic protons, clearly indicating the presence of hindered rotationmore » about the pyrimidine-phenyl bond. Analogues containing asymmetrically substituted aromatic rings exist as mixtures of two rotational isomers (an enantiomeric pair) because of this hindered rotation and the NMR spectra revealed that both isomers (forms A and B) bind to the enzyme with comparable, though unequal, binding energies. In this case two complete sets of bound proton signals were observed. The relative orientations of the two forms have been determined from NOE through-space connections between protons on the ligand and protein. Ternary complexes with NADP{sup {plus}} were also examined.« less

Revisit the modeling of the Saturnian ring atmosphere and ionosphere from the "Cassini Grand Finale" results

NASA Astrophysics Data System (ADS)

Tseng, W. L.; Johnson, R. E.; Tucker, O. J.; Perry, M. E.; Ip, W. H.

2017-12-01

During the Cassini Grand Finale mission, this spacecraft, for the first time, has done the in-situ measurements of Saturn's upper atmosphere and its rings and provides critical information for understanding the coupling dynamics between the main rings and the Saturnian system. The ring atmosphere is the source of neutrals (i.e., O2, H2, H; Tseng et al., 2010; 2013a), which is primarily generated by photolytic decomposition of water ice (Johnson et al., 2006), and plasma (i.e., O2+ and H2+; Tseng et al., 2011) in the Saturnian magnetosphere. In addition, the main rings have strong interaction with Saturn's atmosphere and ionosphere (i.e., a source of oxygen into Saturn's upper atmosphere and/or the "ring rain" in O'Donoghue et al., 2013). Furthermore, the near-ring plasma environment is complicated by the neutrals from both the seasonally dependent ring atmosphere and Enceladus torus (Tseng et al., 2013b), and, possibly, from small grains from the main and tenuous F and G rings (Johnson et al.2017). The data now coming from Cassini Grand Finale mission already shed light on the dominant physics and chemistry in this region of Saturn's magnetosphere, for example, the presence of carbonaceous material from meteorite impacts in the main rings and each gas species have similar distribution in the ring atmosphere. We will revisit the details in our ring atmosphere/ionosphere model to study, such as the source mechanism for the organic material and the neutral-grain-plasma interaction processes.

9975 Shipping package component long-term degradation rates

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

Daugherty, W. L.

Special nuclear materials are being stored in the K-Area Complex using 3013 containers that are held within Model 9975 shipping packages. The service life for these packages in storage was recently increased from 15 to 20 years, since some of these packages have been stored for nearly 15 years. A strategy is also being developed whereby such storage might be extended beyond 20 years. This strategy is based on recent calculations that support acceptable 9975 package performance for 20 years with internal heat loads up to 19 watts, and identifies a lower heat load limit for which the package componentsmore » should degrade at half the bounding rate or less, thus doubling the effective storage life for these lower wattage packages. The components of the 9975 package that are sensitive to aging under storage conditions are the fiberboard overpack and the O-ring seals, although some degradation of the lead shield and outer drum are also possible. This report summarizes degradation rates applicable to lower heat load storage conditions. In particular, the O-ring seals should provide leak-tight performance for more than 40 years in packages for which their maximum temperature is ≤135 °F. Similarly, the fiberboard should remain acceptable in performance of its required safety functions for up to 40 years in packages with a maximum fiberboard temperature ≤125 °F.« less

1-(4,5-Dinitro-10-aza­tricyclo­[6.3.1.02,7]dodeca-2,4,6-trien-10-yl)-2,2,2-trifluoro­ethanone

PubMed Central

Xu, Hao; Quan, Ji-Cai; Xu, Jian; Chen, Jing; Wang, Jin-Tang

2008-01-01

In the title compound, C13H10F3N3O5, a derivative of andrographolide, the five-membered ring adopts an envelope conformation, while the non-planar six-membered ring has a chair conformation. An intra­molecular C—H⋯F hydrogen bond results in the formation of a non-planar six-membered ring adopting a twisted conformation. In the crystal structure, inter­molecular C—H⋯O hydrogen bonds link the mol­ecules into centrosymmetric dimers. PMID:21581393

N-(2-Allyl-4-eth­oxy-2H-indazol-5-yl)-4-methyl­benzene­sulfonamide

PubMed Central

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Viale, Maurizio; Saadi, Mohamed; El Ammari, Lahcen

2014-01-01

The indazole ring system of the title compound, C19H21N3O3S, is almost planar (r.m.s. deviation = 0.0192 Å) and forms dihedral angles of 77.99 (15) and 83.9 (3)° with the benzene ring and allyl group, respectively. In the crystal, centrosymmetrically related mol­ecules are connected by pairs of N—H⋯O hydrogen bonds into dimers, which are further linked by C—H⋯O hydrogen bonds, forming columns parallel to the b axis. PMID:24860413

N-(1-Allyl-3-chloro-4-eth­oxy-1H-indazol-5-yl)-4-methyl­benzene­sulfonamide

PubMed Central

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2014-01-01

In the title compound, C19H20ClN3O3S, the benzene ring is inclined to the indazole ring system by 51.23 (8)°. In the crystal, mol­ecules are linked by pairs of N—H⋯O hydrogen bonds, forming inversion dimers which stack in columns parallel to [011]. The atoms in the allyl group are disordered over two sets of sites with an occupancy ratio of 0.624 (8):0.376 (8). PMID:24940237

The Shapers

NASA Image and Video Library

2015-01-26

Two masters of their craft are caught at work shaping Saturn's rings. Pandora (upper right) sculpts the F ring, as does nearby Prometheus (not seen in this image). Meanwhile, Daphnis is busy holding open the Keeler gap (bottom center), its presence revealed here by the waves it raises on the gap's edge. The faint moon is located where the inner and outer waves appear to meet. Also captured in this image, shining through the F ring above the image center, is a single star. Although gravity is by its very nature an attractive force, moons can interact with ring particles in such a way that they effectively push ring particles away from themselves. Ring particles experience tiny gravitational "kicks" from these moons and subsequently collide with other ring particles, losing orbital momentum. The net effect is for moons like Pandora (50 miles or 81 kilometers across) and Daphnis (5 miles or 8 kilometers across) to push ring edges away from themselves. The Keeler gap is the result of just such an interaction. This view looks toward the unilluminated side of the rings from about 50 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 30, 2013. http://photojournal.jpl.nasa.gov/catalog/PIA18298

Crystal structure of N-(1-allyl-3-chloro-4-eth­oxy-1H-indazol-5-yl)-4-meth­oxybenzene­sulfonamide

PubMed Central

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2014-01-01

In the title compound, C19H20ClN3O4S, the benzene ring is inclined to the indazole ring system (r.m.s. deviation = 0.014 Å) by 65.07 (8)°. The allyl and eth­oxy groups are almost normal to the indazole ring, as indicated by the respective torsion angles [N—N—C—C = 111.6 (2) and C—C—O—C = −88.1 (2)°]. In the crystal, mol­ecules are connected by N—H⋯N hydrogen bonds, forming helical chains propagating along [010]. The chains are linked by C—H⋯O hydrogen bonds, forming a three-dimensional network. PMID:25309208

Findings on rings and inner satellites of Saturn of Pioneer 11

NASA Astrophysics Data System (ADS)

van Allen, J. A.

1982-09-01

The introductory part of this paper gives a short account of the theory of absorption by planetary rings and satellites of energetic charged particles that are trapped in a planet's magnetic field and describes the observable consequences of such absorption processes. The previously published University of Iowa observations of absorption features during Pioneer 11's passage through Saturn's inner radiation belt on 1 September 1979 are critically reanalyzed and related to other evidence on rings and satellites inside 2.9 Saturn radii, especially that from the imaging system on Voyagers 1 and 2. It is found (a) that satellites 1979 S1, 1979 S2, and 1980 S3 are almost certainly identical; (b) that the evidence for 1979 S4 is weak to nonexistent; (c) that 1979 S5 and two other nearby absorption features and 1979 S6 and one other nearby absorption feature are probably caused by longitudinal and radial structure of Ring F and not by satellites; and (d) that absorption feature 1979 S3 at 169,200 + or - 600 km is identified with the optically observed Ring G.

Interpretation of high rate dust measurements with the Cassini dust detector CDA

NASA Astrophysics Data System (ADS)

Kempf, Sascha

2008-03-01

For two years the cosmic dust analyser (CDA) onboard the Cassini spacecraft has been exploring the dust environment of Saturn [Srama, R., Kempf, S., Moragas-Klostermeyer, G., Helfert, S., Ahrens, T. J., Altobelli, N., Auer, S., Beckmann, U., Bradley, J.G., Burton, M., Dikarev, V.V., Economou, T., Fechtig, H., Green, S.F., Grande, M., Havnes, O., Hillier, J.K., Horanyi, M., Igenbergs, E., Jessberger, E.K., Johnson, T.V., Krüger, H., Matt, G., McBride, N., Mocker, A., Lamy, P., Linkert, D., Linkert, G., Lura, F., McDonnell, J.A.M., Möhlmann, D., Morfill, G.E., Postberg, F., Roy, M., Schwehm, G.H., Spahn, F., Svestka, J., Tschernjawski, V., Tuzzolino, A.J., Wäsch, R., Grün, E., 2006. In situ dust measurements in the inner Saturnian system. Planet. Space Sci. 54, 967-987]. One major goal of the CDA instruments is to investigate Saturn's enigmatic E ring - the largest known planetary ring of the solar system. The sophisticated main detector (dust analyser - DA) of CDA is rather slow when processing the impact data, and limits the detectable number of impacts to 60min-1 [Srama, R., Ahrens, T., Altobelli, N., Auer, S., Bradley, J., Burton, M., Dikarev, V., Economou, T., Fechtig, H., Görlich, M., Grande, M., Graps, A., Grün, E., Havnes, O., Helfert, S., Horányi, M., Igenbergs, E., Jeßberger, E., Johnson, T., Kempf, S., Krivov, A., Krüger, H., Mocker-Ahlreep, A., Moragas-Klostermeyer, G., Lamy, P., Landgraf, M., Linkert, D., Linkert, G., Lura, F., McDonnel, J., Möhlmann, D., Morfill, G., Müller, M., Roy, M., Schäfer, G., Schlotzhauer, G., Schwehm, G., Spahn, F., Stübig, M., Svestka, J., Tschernjawski, V., Tuzzolino, A., Wäsch, R., Zook, H., 2004. The Cassini cosmic dust analyser. Space Sci. Rev. 114, 465-518]. However, measurements by the CDA high rate detector (HRD) imply that the DA impact rates in the inner core of the E ring exceed 1000min-1. Clearly, to investigate dust-rich environments with the DA requires knowledge about the instrument performance at high impact rates. In this paper, we study the dependence of the number of detected impacts on the average impact rate arising from a Poisson process. We demonstrate the validity of the resulting expressions by comparing them with Monte Carlo (MC) simulations of the DA performance. We argue that DA measurements provide meaningful impact rate estimates even if the DA detects slightly less than 60 impacts per minute. Finally, we apply the derived expressions to a DA E ring measurement.

Constacyclic codes over the ring F_q+v{F}_q+v2F_q and their applications of constructing new non-binary quantum codes

NASA Astrophysics Data System (ADS)

Ma, Fanghui; Gao, Jian; Fu, Fang-Wei

2018-06-01

Let R={F}_q+v{F}_q+v2{F}_q be a finite non-chain ring, where q is an odd prime power and v^3=v. In this paper, we propose two methods of constructing quantum codes from (α +β v+γ v2)-constacyclic codes over R. The first one is obtained via the Gray map and the Calderbank-Shor-Steane construction from Euclidean dual-containing (α +β v+γ v2)-constacyclic codes over R. The second one is obtained via the Gray map and the Hermitian construction from Hermitian dual-containing (α +β v+γ v2)-constacyclic codes over R. As an application, some new non-binary quantum codes are obtained.

Diagnostic Systems Plan for the Advanced Light Source Top-OffUpgrade

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

Barry, Walter; Chin, Mike; Robin, David

2005-05-10

The Advanced Light Source (ALS) will soon be upgraded to enable top-off operations [1], in which electrons are quasi-continuously injected to produce constant stored beam current. The upgrade is structured in two phases. First, we will upgrade our injector from 1.5 GeV to 1.9 GeV to allow full energy injection and will start top-off operations. In the second phase, we will upgrade the Booster Ring (BR) with a bunch cleaning system to allow high bunch purity top-off injection. A diagnostics upgrade will be crucial for success in both phases of the top-off project, and our plan for it is describedmore » in this paper. New booster ring diagnostics will include updated beam position monitor (BPM) electronics, a tune monitoring system, and a new scraper. Two new synchrotron light monitors and a beam stop will be added to the booster-to-storage ring transfer line (BTS), and all the existing beam current monitors along the accelerator chain will be integrated into a single injection efficiency monitoring application. A dedicated bunch purity monitor will be installed in the storage ring (SR). Together, these diagnostic upgrades will enable smooth commissioning of the full energy injector and a quick transition to high quality top-off operation at the ALS.« less

Rotating machinery dynamics simulation. I. Rigid systems with ball bearing nonlinearities and outer ring ovality under rotating unbalance excitation

PubMed

el-Saeidy

2000-02-01

The radial clearance in rolling bearing systems, required to compensate for dimensional changes associated with thermal expansion of the various parts during operation, may cause dimensional attrition and comprise bearing life, if unloaded operation occurs and balls skid [D. Childs and D. Moyer, ASME J. Eng. Gas Turb. Power 107, 152-159 (1985)]. Also, it can cause jumps in the response to unbalance excitation. These undesirable effects may be eliminated by introducing two or more loops into one of the bearing races so that at least two points of the ring circumference provide a positive zero clearance [D. Childs, Handbook of Rotordynamics, edited by F. Ehrich (McGraw-Hill, NY, 1992)]. The deviation of the outer ring with two loops, known as ovality, is one of the bearing distributed defects. Although this class of imperfections has received much work, none of the available studies has simulated the effect of the outer ring ovality on the dynamic behavior of rotating machinery under rotating unbalance with consideration of ball bearing nonlinearities, shaft elasticity, and speed of rotation. To fill this gap, the equations of motion of a rotor-ball bearing system are formulated using finite-elements (FE) discretization and Lagrange's equations. The analyses are specialized to a rigid-rotor system, by retaining the rigid body modes only in the FE solution. Samples of the results are presented in both time domain and frequency domain for a system with and without outer ring ovality. It is found that with ideal bearings (no ovality), the vibration spectrum is qualitatively and quantitatively the same in both the horizontal and vertical directions. When the ring ovality is introduced, however, the spectrum in both orthogonal planes is no longer similar. And magnitude of the bearing load has increased in the form of repeated random impacts, between balls and rings, in the horizontal direction (direction of maximum clearance) compared to a continuous contact along the vertical direction (direction of positive zero clearance). This underlines the importance of the vibration measuring probe's direction, with respect to the outer ring axes, to capture impact-induced vibrations. Moreover, when the harmonic excitation is increased for a system with ideal bearings, the spectral peaks above forcing frequency have shifted to a higher-frequency region, indicating some sort of a hard spring mechanism inherent in the system. Another observation, is that for the same external excitation, vibration amplitude at forcing frequency in the bearing force spectrum is the same for systems with or without outer ring ovality.

ATLAS F MISSILE FIELDS IN THE UNITED STATES, ATLAS F ...

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

ATLAS F MISSILE FIELDS IN THE UNITED STATES, ATLAS F- TEXAS RING OF TWELVE - Dyess Air Force Base, Atlas F Missle Site S-8, Approximately 3 miles east of Winters, 500 feet southwest of Highway 177, Winters, Runnels County, TX

Control of intramolecular π-π stacking interaction in cationic iridium complexes via fluorination of pendant phenyl rings.

PubMed

He, Lei; Ma, Dongxin; Duan, Lian; Wei, Yongge; Qiao, Juan; Zhang, Deqiang; Dong, Guifang; Wang, Liduo; Qiu, Yong

2012-04-16

Intramolecular π-π stacking interaction in one kind of phosphorescent cationic iridium complexes has been controlled through fluorination of the pendant phenyl rings on the ancillary ligands. Two blue-green-emitting cationic iridium complexes, [Ir(ppy)(2)(F2phpzpy)]PF(6) (2) and [Ir(ppy)(2)(F5phpzpy)]PF(6) (3), with the pendant phenyl rings on the ancillary ligands substituted with two and five fluorine atoms, respectively, have been synthesized and compared to the parent complex, [Ir(ppy)(2)(phpzpy)]PF(6) (1). Here Hppy is 2-phenylpyridine, F2phpzpy is 2-(1-(3,5-difluorophenyl)-1H-pyrazol-3-yl)pyridine, F5phpzpy is 2-(1-pentafluorophenyl-1H-pyrazol-3-yl)-pyridine, and phpzpy is 2-(1-phenyl-1H-pyrazol-3-yl)pyridine. Single crystal structures reveal that the pendant phenyl rings on the ancillary ligands stack to the phenyl rings of the ppy ligands, with dihedral angles of 21°, 18°, and 5.0° between least-squares planes for complexes 1, 2, and 3, respectively, and centroid-centroid distances of 3.75, 3.65, and 3.52 Å for complexes 1, 2, and 3, respectively, indicating progressively reinforced intramolecular π-π stacking interactions from complexes 1 to 2 and 3. Compared to complex 1, complex 3 with a significantly reinforced intramolecular face-to-face π-π stacking interaction exhibits a significantly enhanced (by 1 order of magnitude) photoluminescent efficiency in solution. Theoretical calculations reveal that in complex 3 it is unfavorable in energy for the pentafluorophenyl ring to swing by a large degree and the intramolecular π-π stacking interaction remains on the lowest triplet state. © 2012 American Chemical Society

Thermal Barrier/Seal for Extreme Temperature Applications

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Dunlap, Patrick H., Jr.; Phelps, Jack; Bauer, Paul; Bond, Bruce; McCool, Alex (Technical Monitor)

2002-01-01

Large solid rocket motors, as found on the Space Shuttle, are fabricated in segments for manufacturing considerations, bolted together, and sealed using conventional Viton O-ring seals. Similarly the nine large solid rocket motor nozzles are assembled from several different segments, bolted together, and sealed at six joint locations using conventional O-ring seals. The 5500 F combustion gases are generally kept a safe distance away from the seals by thick layers of phenolic or rubber insulation. Joint-fill compounds, including RTV (room temperature vulcanized compound) and polysulfide filler, are used to fill the joints in the insulation to prevent a direct flow-path to the O-rings. Normally these two stages of protection are enough to prevent a direct flow-path of the 900-psi hot gases from reaching the temperature-sensitive O-ring seals. However, in the current design 1 out of 15 Space Shuttle solid rocket motors experience hot gas effects on the Joint 6 wiper (sacrificial) O-rings. Also worrisome is the fact that joints have experienced heat effects on materials between the RTV and the O-rings, and in two cases O-rings have experienced heat effects. These conditions lead to extensive reviews of the post-flight conditions as part of the effort to monitor flight safety. We have developed a braided carbon fiber thermal barrier to replace the joint fill compounds in the Space Shuttle solid rocket motor nozzles to reduce the incoming 5500 F combustion gas temperature and permit only cool (approximately 100 F) gas to reach the temperature-sensitive O-ring seals. Implementation of this thermal barrier provides more robust, consistent operation with shorter turn around times between Shuttle launches.

(E)-3-[3,4-Bis(meth-oxy-methoxy)phen-yl]-1-(7-hy-droxy-5-meth-oxy-2,2-dimethyl-chroman-8-yl)prop-2-en-1-one.

PubMed

Hashim, Nur Athirah; Ahmad, Farediah; Basar, Norazah; Awang, Khalijah; Ng, Seik Weng

2011-09-01

The reaction of 5,6-(2,2-dimethyl-chroman-yl)-2-hy-droxy-4-meth-oxy-acetophenone and 3,4-bis-(meth-oxy-meth-yloxy)benzaldehyde affords the intense orange title chalcone derivative, C(25)H(30)O(8). The two benzene rings are connected through a -C(=O)-CH=CH- (propenone) unit, which is in an E conformation; the ring with the hy-droxy substitutent is aligned at 19.5 (2)° with respect to this unit, whereas the ring with the meth-oxy-meth-yloxy substituent is aligned at 9.3 (3)°. The dihedral angle between the rings is 19.38 (10)°. The hy-droxy group engages in an intra-molecular O-H⋯O hydrogen bond with the carbonyl O atom of the propenone unit, generating an S(5) ring.

Function of Coenzyme F420 in Aerobic Catabolism of 2,4,6-Trinitrophenol and 2,4-Dinitrophenol by Nocardioides simplex FJ2-1A

PubMed Central

Ebert, Sybille; Rieger, Paul-Gerhard; Knackmuss, Hans-Joachim

1999-01-01

2,4,6-Trinitrophenol (picric acid) and 2,4-dinitrophenol were readily biodegraded by the strain Nocardioides simplex FJ2-1A. Aerobic bacterial degradation of these π-electron-deficient aromatic compounds is initiated by hydrogenation at the aromatic ring. A two-component enzyme system was identified which catalyzes hydride transfer to picric acid and 2,4-dinitrophenol. Enzymatic activity was dependent on NADPH and coenzyme F420. The latter could be replaced by an authentic preparation of coenzyme F420 from Methanobacterium thermoautotrophicum. One of the protein components functions as a NADPH-dependent F420 reductase. A second component is a hydride transferase which transfers hydride from reduced coenzyme F420 to the aromatic system of the nitrophenols. The N-terminal sequence of the F420 reductase showed high homology with an F420-dependent NADP reductase found in archaea. In contrast, no N-terminal similarity to any known protein was found for the hydride-transferring enzyme. PMID:10217752

N-body simulations of viscous instability of planetary rings

NASA Astrophysics Data System (ADS)

Salo, Heikki; Schmidt, Jürgen

2010-04-01

We study viscous instability of planetary rings in terms of N-body simulations. We show that for rings composed of fairly elastic particles (e.g. as in Hatzes et al. [Hatzes, A., Bridges, F.G., Lin, D.N.C., 1988. Collisional properties of ice spheres at low impact velocities. Mon. Not. R. Astron. Soc. 231, 1091-1115]) the instability may lead to the spontaneous formation of dense ringlets in a background of lower density. In most parts of Saturn's rings the particle collisions are probably much more dissipative, as suggested by the presence of self-gravity wakes, and classic viscous instability should be suppressed. However, our results demonstrate that the mechanism of viscous instability itself is valid. The dynamical effects of size-dependent elasticity in a system with a size distribution have never been studied before. We show that this may in principle lead to a size-selective viscous instability, small particles concentrating on ringlets against the more uniform background of large particles.

Saturn's 15th moon, 1980S28

NASA Technical Reports Server (NTRS)

1980-01-01

Voyager 1 has found a 15th moon orbiting Saturn, visible near the bottom of this picture taken on Nov. 6, 1980, when the spacecraft was still 8 million kilometers (5 million miles) from Saturn. Voyager imaging team scientists discovered the moon Nov. 7, 1980, in the first of several programmed searches for new satellites of Saturn. The unique location of the 15th satellite, just 800 kilometers (500 miles) outside the outer edge of the A-ring, is especially significant in that this small body, approximately 100 kilometers (50 miles) in diameter, may be responsible for defining the outer edge of Saturn's bright ring system. The orbital period of the new satellite is approximately 14 hours, 20 minutes, the shortest orbit of any of Saturn's known satellites. The very narrow F-ring, approximately 4,000 kilometers (2,500 miles) outside the outer edge of the A-ring, is seen prominently in this picture. The Voyager Project is managed for NASA by the Jet Propulsion Laboratory, Pasadena, Calif.

HUBBLE CAPTURES UNVEILING OF PLANETARY NEBULA

NASA Technical Reports Server (NTRS)

2002-01-01

This Wide Field and Planetary Camera 2 image captures the infancy of the Stingray nebula (Hen-1357), the youngest known planetary nebula. In this image, the bright central star is in the middle of the green ring of gas. Its companion star is diagonally above it at 10 o'clock. A spur of gas (green) is forming a faint bridge to the companion star due to gravitational attraction. The image also shows a ring of gas (green) surrounding the central star, with bubbles of gas to the lower left and upper right of the ring. The wind of material propelled by radiation from the hot central star has created enough pressure to blow open holes in the ends of the bubbles, allowing gas to escape. The red curved lines represent bright gas that is heated by a 'shock' caused when the central star's wind hits the walls of the bubbles. The nebula is as large as 130 solar systems, but, at its distance of 18,000 light-years, it appears only as big as a dime viewed a mile away. The Stingray is located in the direction of the southern constellation Ara (the Altar). The colors shown are actual colors emitted by nitrogen (red), oxygen (green), and hydrogen (blue). The filters used were F658N ([N II]), F502N ([O III]), and F487N (H-beta). The observations were made in March 1996. Credit: Matt Bobrowsky, Orbital Sciences Corporation and NASA

Planetary period oscillations in Saturn's magnetosphere: New results from the F-ring and proximal orbits

NASA Astrophysics Data System (ADS)

Provan, G.; Cowley, S. W. H.; Bunce, E. J.; Hunt, G. J.; Dougherty, M. K.

2017-12-01

We investigate planetary period oscillations (PPOs) in Saturn's magnetosphere using Cassini magnetic field data during the high cadence ( 7 days) F-ring and proximal orbits. Previous results have shown that there are two PPO systems, one in each hemisphere. Both PPO periods show seasonal dependence, and since mid-2014 the Northern PPO period has been 10.8 h and the Southern PPO period 10.7 h. The beat period of the two oscillations is 45 days. Previous results demonstrated that in the Northern (Southern) polar region only pure Northern (Southern) oscillations can be observed, whilst in the equatorial region both oscillations are present and constructively and destructively interfere over the beat-cycle of the two oscillations. The PPOs are believed to be driven by twin-cell convection patterns in the polar ionosphere/thermosphere regions, with two systems of field-aligned currents transmitting the PPO flows to the magnetospheric plasma.The F-ring and proximal orbits uniquely observe the PPOs over 6 orbits during each PPO beat cycle. This high-cadence data demonstrates that over a beat cycle both the periods and amplitudes of the PPO observed within the each polar region are modulated by the PPO system from the opposite hemisphere. When the two oscillations are in phase (anti-phase) the `drag' of one system on the other acts to decrease (increase) the amplitude of the oscillations and the two PPO periods diverge (converge). We present a theoretical model showing that this coupling is due to the PPO flows from one hemisphere not just being communicated to the magnetosphere as previously assumed, but also to the opposite hemisphere. The result is inter-hemispheric coupling of the PPO flow systems within the ionosphere/thermosphere system, so that the northern PPO system drives a northern twin-cell convection pattern in the southern hemisphere, and vice versa, thus leading to the observed polar modulations of the PPOs.We will also present PPO phase models determined throughout the entire Cassini mission. These models define the orientations of the two PPO current/field systems with respect to the Sun at any instant of time, thus allowing any Saturnian observations to be organized by PPO phase. The models are freely available to the community.

Observational Limits for Rings and Debris at Pluto from New Horizons

NASA Astrophysics Data System (ADS)

Throop, Henry B.; Lauer, Tod R.; Showalter, Mark R.; Weaver, Harold A.; Stern, S. Alan; Spencer, John R.; Buie, Marc W.; Hamilton, Douglas P.; Porter, Simon Bernard; Verbiscer, Anne J.; Young, Leslie; Olkin, Catherine; Ennico, Kimberly; New Horizons Science Team

2017-10-01

NASA's New Horizons missions flew past Pluto on July 14, 2015. New Horizons conducted an extensive search for orbital material at Pluto, using deep imaging at backscatter and forward-scatter, direct in situ dust detector measurements, and stellar occultations. We searched the entire region from the surface of Pluto outward to the Pluto-Charon Hill radius (6.4 x 106 km = 100 times Hydra's orbital radius), using the spacecraft's LORRI and MVIC cameras.No material was found to a normal I/F limit of 2 x 10-8 for 1500 km-wide rings, and 7 x 10-9 for 12,000 km-wide rings. Our results are consistent with dynamical studies that show the lifetime of dust in the Pluto system is short, with the loss dominated by solar radiation pressure and gravitational perturbations.

Passage through the Ring Plane

NASA Image and Video Library

2004-06-03

The path that lies ahead for the Cassini-Huygens mission is indicated in this image which illustrates where the spacecraft will be just 27 days from now, when it arrives at Saturn and crosses the ring plane 33 minutes before performing its critical orbital insertion maneuver. The X indicates the point where Cassini will pierce the ring plane on June 30, 2004, going from south to north of the ring plane, 33 minutes before the main engine fires to begin orbital insertion. The indicated point is between the narrow F-ring on the left and Saturn's tenuous G-ring which is too faint to be seen in this exposure. The image was taken on May 11, 2004 when the spacecraft was 26.3 million kilometers (16.3 million miles) from Saturn. Image scale is 158 kilometers (98 miles) per pixel. Moons visible in this image: Janus (181 kilometers or 113 miles across), one of the co-orbital moons; Pandora (84 kilometers or 52 miles across), one of the F ring shepherding moons; and Enceladus (499 kilometers or 310 miles across), a moon which may be heated from within and thus have a liquid sub-surface ocean. http://photojournal.jpl.nasa.gov/catalog/PIA06061

Edge-on View of Saturn's Rings

NASA Technical Reports Server (NTRS)

1996-01-01

TOP - This is a NASA Hubble Space Telescope snapshot of Saturn with its rings barely visible. Normally, astronomers see Saturn with its rings tilted. Earth was almost in the plane of Saturn's rings, thus the rings appear edge-on.

In this view, Saturn's largest moon, Titan, is casting a shadow on Saturn. Titan's atmosphere is a dark brown haze. The other moons appear white because of their bright, icy surfaces. Four moons - from left to right, Mimas, Tethys, Janus, and Enceladus - are clustered around the edge of Saturn's rings on the right. Two other moons appear in front of the ring plane. Prometheus is on the right edge; Pandora, on the left. The rings also are casting a shadow on Saturn because the Sun was above the ring plane.

BOTTOM - This photograph shows Saturn with its rings slightly tilted. The moon called Dione, on the lower right, is casting a long, thin shadow across the whole ring system due to the setting Sun on the ring plane. The moon on the upper left of Saturn is Tethys.

Astronomers also are studying the unusual appearance of Saturn's rings. The bottom image displays a faint, narrow ring, the F-ring just outside the main ring, which normally is invisible from Earth. Close to the edge of Saturn's disk, the front section of rings seem brighter and more yellow than the back due to the additional lumination by yellowish Saturn.

The color images were assembled from separate exposures taken August 6 (top) and November 17 (bottom), 1995 with the Wide Field Planetary Camera-2.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Demonstration of Ice-Free Cathodic Protection Systems for Water Storage Tanks at Fort Drum: Final Report on Project AR-F-318 for FY05

DTIC Science & Technology

2007-06-01

and immovable with fingers. Body side rivet base and outside rivet burr should be flat against the material. Bent rivets will fail under stress ...such as using knots, tying around sharp edges, etc.) and maximum permitted free fall distance. Also, to be stressed are the importance of inspections...limitations; e. Application limits; f. Proper hook -up, anchoring and tie-off techniques, including the proper dee-ring or other attachment point to use on

Structure-Stability Relationships of Polymers Based on Thermogravimetric Analysis Data. Part 1. Polyaliphatics, Polyalicyclics, Spiro Polymers and Phenylene-R-Polymers

DTIC Science & Technology

1974-12-01

Polymerization 13 9. Polymers with Bridged Ring Systems 14 10. Spiro Polymers 14 11. Polyphenylene s 16 12. Phenol - Formaldehyde Resins 17 13. Polyphenylene... Formaldehyde Resins A wide variety of phenol- formaldehyde resins , cured with various curing agents, has been evaluated. The Tdec’s (N 2 ), which...415 0 570 415 540C 2- 410 0 -CHI - 0- c-Ci.f-CCH = 1-eC.- 390 540 0 (Phenol- Formaldehyde Resins ) -CVH- (aliph.) 390 / F_ 535 0 - CHL" (epoxy

Little Tuber Moon

NASA Image and Video Library

2010-01-05

Saturn small moon Prometheus, slightly overexposed in this image taken by NASA Cassini spacecraft, shows off its potato-like shape as it orbits in the Roche Division between the A ring and thin F ring.

Nanoscale architecture of the Schizosaccharomyces pombe contractile ring.

PubMed

McDonald, Nathan A; Lind, Abigail L; Smith, Sarah E; Li, Rong; Gould, Kathleen L

2017-09-15

The contractile ring is a complex molecular apparatus which physically divides many eukaryotic cells. Despite knowledge of its protein composition, the molecular architecture of the ring is not known. Here we have applied super-resolution microscopy and FRET to determine the nanoscale spatial organization of Schizosaccharomyces pombe contractile ring components relative to the plasma membrane. Similar to other membrane-tethered actin structures, we find proteins localize in specific layers relative to the membrane. The most membrane-proximal layer (0-80 nm) is composed of membrane-binding scaffolds, formin, and the tail of the essential myosin-II. An intermediate layer (80-160 nm) consists of a network of cytokinesis accessory proteins as well as multiple signaling components which influence cell division. Farthest from the membrane (160-350 nm) we find F-actin, the motor domains of myosins, and a major F-actin crosslinker. Circumferentially within the ring, multiple proteins proximal to the membrane form clusters of different sizes, while components farther from the membrane are uniformly distributed. This comprehensive organizational map provides a framework for understanding contractile ring function.

Nanoscale architecture of the Schizosaccharomyces pombe contractile ring

PubMed Central

McDonald, Nathan A; Lind, Abigail L; Smith, Sarah E; Li, Rong

2017-01-01

The contractile ring is a complex molecular apparatus which physically divides many eukaryotic cells. Despite knowledge of its protein composition, the molecular architecture of the ring is not known. Here we have applied super-resolution microscopy and FRET to determine the nanoscale spatial organization of Schizosaccharomyces pombe contractile ring components relative to the plasma membrane. Similar to other membrane-tethered actin structures, we find proteins localize in specific layers relative to the membrane. The most membrane-proximal layer (0–80 nm) is composed of membrane-binding scaffolds, formin, and the tail of the essential myosin-II. An intermediate layer (80–160 nm) consists of a network of cytokinesis accessory proteins as well as multiple signaling components which influence cell division. Farthest from the membrane (160–350 nm) we find F-actin, the motor domains of myosins, and a major F-actin crosslinker. Circumferentially within the ring, multiple proteins proximal to the membrane form clusters of different sizes, while components farther from the membrane are uniformly distributed. This comprehensive organizational map provides a framework for understanding contractile ring function. PMID:28914606

Nearshore Survey System Evaluation

DTIC Science & Technology

2017-12-01

ER D C/ CH L TR -1 7- 19 Coastal Field Data Collection Program Nearshore Survey System Evaluation Co as ta l a nd H yd ra ul ic s La...Collection Program ERDC/CHL TR-17-19 December 2017 Nearshore Survey System Evaluation Michael F. Forte, William A. Birkemeier, and J. Robert Mitchell...No. 462585 ERDC/CHL TR-17-19 ii Abstract This report evaluates the accuracy of two systems for surveying the beach and nearshore zone. The 10

Drosophila F-BAR protein Syndapin contributes to coupling the plasma membrane and contractile ring in cytokinesis.

PubMed

Takeda, Tetsuya; Robinson, Iain M; Savoian, Matthew M; Griffiths, John R; Whetton, Anthony D; McMahon, Harvey T; Glover, David M

2013-08-07

Cytokinesis is a highly ordered cellular process driven by interactions between central spindle microtubules and the actomyosin contractile ring linked to the dynamic remodelling of the plasma membrane. The mechanisms responsible for reorganizing the plasma membrane at the cell equator and its coupling to the contractile ring in cytokinesis are poorly understood. We report here that Syndapin, a protein containing an F-BAR domain required for membrane curvature, contributes to the remodelling of the plasma membrane around the contractile ring for cytokinesis. Syndapin colocalizes with phosphatidylinositol 4,5-bisphosphate (PI(4,5)P₂) at the cleavage furrow, where it directly interacts with a contractile ring component, Anillin. Accordingly, Anillin is mislocalized during cytokinesis in Syndapin mutants. Elevated or diminished expression of Syndapin leads to cytokinesis defects with abnormal cortical dynamics. The minimal segment of Syndapin, which is able to localize to the cleavage furrow and induce cytokinesis defects, is the F-BAR domain and its immediate C-terminal sequences. Phosphorylation of this region prevents this functional interaction, resulting in reduced ability of Syndapin to bind to and deform membranes. Thus, the dephosphorylated form of Syndapin mediates both remodelling of the plasma membrane and its proper coupling to the cytokinetic machinery.

Potato Pair

NASA Image and Video Library

2010-01-14

Pandora and Prometheus, the shepherding moons of the F ring, orbit inside and outside the thin ring. The elongated, potato-like shapes of the two moons are both visible in this image taken by NASA Cassini spacecraft.

FY 1980 Report on Dye Laser Materials

DTIC Science & Technology

1981-02-01

C02H H Rh 19 H C2H 5 CH3 CO9H H i Rh6G H C2H 5 CH3 Co2 C2H5 H RhB C2H5 C2H!5 H CO,H H Rh3B C2A5 C2H5 H CO2CH 5 H Rh 101 RING- RING RING...Dye designations Ring SRh 101 Rh 101 - Diethyl SRh B Rh B Rhb 3B Mono ethyl (methyl) -- Rh 19 (116) Rh 6G Unsubstituted -- Rh 110 Rh 123 Nominal Single...Broadband Lasing Wave-lengths of the Rhodamine Dyes. Lasing Wavelength, n Approximate Dye Conc. x 104 Range Midpoint Rh 110 1.0 567-577 572 2.0 Rh 123

Operating characteristics of a three-piece-inner-ring large-bore roller bearing to speeds of 3 million DN

NASA Technical Reports Server (NTRS)

Schuller, F. T.

1984-01-01

A 118 mm bore roller bearing with a three piece inner ring ran successfully at 300,000 DN for 20 hr. Provisions were made for lubrication and cooling through the inner ring. In some tests the outer ring was also cooled. Power loss within the bearing increased with both speed and total oil flow rate to the inner ring. Outer ring temperature decreased by as much as 22 K (40 F) when outer ring cooling was employed whereas inner ring temperature remained essentially constant. Cage slip was greatly reduced or even eliminated by using a bearing with a very tight clearance at operating speed. A three piece inner ring bearing had higher inner ring temperatures and less temperature difference between the inner and outer rings than a conventional one piece inner ring bearing.

POTENTIAL IMPACT OF BLENDING RESIDUAL SOLIDS FROM TANKS 18/19 MOUNDS WITH TANK 7 OPERATIONS

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

Eibling, R; Erich Hansen, E; Bradley Pickenheim, B

2007-03-29

High level waste tanks 18F and 19F have residual mounds of waste which may require removal before the tanks can be closed. Conventional slurry pump technology, previously used for waste removal and tank cleaning, has been incapable of removing theses mounds from tanks 18F and 19F. A mechanical cleaning method has been identified that is potentially capable of removing and transferring the mound material to tank 7F for incorporation in a sludge batch for eventual disposal in high level waste glass by the Defense Waste Processing Facility. The Savannah River National Laboratory has been requested to evaluate whether the materialmore » transferred from tanks 18F/19F by the mechanical cleaning technology can later be suspended in Tank 7F by conventional slurry pumps after mixing with high level waste sludge. The proposed mechanical cleaning process for removing the waste mounds from tanks 18 and 19 may utilize a high pressure water jet-eductor that creates a vacuum to mobilize solids. The high pressure jet is also used to transport the suspended solids. The jet-eductor system will be mounted on a mechanical crawler for movement around the bottom of tanks 18 and 19. Based on physical chemical property testing of the jet-eductor system processed IE-95 zeolite and size-reduced IE-95 zeolite, the following conclusions were made: (1) The jet-eductor system processed zeolite has a mean and median particle size (volume basis) of 115.4 and 43.3 microns in water. Preferential settling of these large particles is likely. (2) The jet-eductor system processed zeolite rapidly generates settled solid yield stresses in excess of 11,000 Pascals in caustic supernates and will not be easily retrieved from Tank 7 with the existing slurry pump technology. (3) Settled size-reduced IE-95 zeolite (less than 38 microns) in caustic supernate does not generate yield stresses in excess of 600 Pascals in less than 30 days. (4) Preferential settling of size-reduced zeolite is a function of the amount of sludge and the level of dilution for the mixture. (5) Blending the size-reduced zeolite into larger quantities of sludge can reduce the amount of preferential settling. (6) Periodic dilution or resuspension due to sludge washing or other mixing requirements will increase the chances of preferential settling of the zeolite solids. (7) Mixtures of Purex sludge and size-reduced zeolite did not produce yield stresses greater than 200 Pascals for settling times less than thirty days. Most of the sludge-zeolite blends did not exceed 50 Pascals. These mixtures should be removable by current pump technology if sufficient velocities can be obtained. (8) The settling rate of the sludge-zeolite mixtures is a function of the ionic strength (or supernate density) and the zeolite- sludge mixing ratio. (9) Simulant tests indicate that leaching of Si may be an issue for the processed Tank 19 mound material. (10) Floating zeolite fines observed in water for the jet-eductor system and size-reduced zeolite were not observed when the size-reduced zeolite was blended with caustic solutions, indicating that the caustic solutions cause the fines to agglomerate. Based on the test programs described in this report, the potential for successfully removing Tank 18/19 mound material from Tank 7 with the current slurry pump technology requires the reduction of the particle size of the Tank 18/19 mound material.« less

How the Enceladus dust plume feeds Saturn’s E ring

NASA Astrophysics Data System (ADS)

Kempf, Sascha; Beckmann, Uwe; Schmidt, Jürgen

2010-04-01

Pre-Cassini models of Saturn's E ring [Horányi, M., Burns, J., Hamilton, D., 1992. Icarus 97, 248-259; Juhász, A., Horányi, M., 2002. J. Geophys. Res. 107, 1-10] failed to reproduce its peculiar vertical structure inferred from Earth-bound observations [de Pater, I., Martin, S.C., Showalter, M.R., 2004. Icarus 172, 446-454]. After the discovery of an active ice-volcanism of Saturn's icy moon Enceladus the relevance of the directed injection of particles for the vertical ring structure of the E ring was swiftly recognised [Juhász, A., Horányi, M., Morfill, G.E., 2007. Geophys. Res. Lett. 34, L09104; Kempf, S., Beckmann, U., Moragas-Klostermeyer, G., Postberg, F., Srama, R., Economou, T., Schmidt, J., Spahn, F., Grün, E., 2008. Icarus 193, 420-437]. However, simple models for the delivery of particles from the plume to the ring predict a too small vertical ring thickness and overestimate the amount of the injected dust. Here we report on numerical simulations of grains leaving the plume and populating the dust torus of Enceladus. We run a large number of dynamical simulations including gravity and Lorentz force to investigate the earliest phase of the ring particle life span. The evolution of the electrostatic charge carried by the initially uncharged grains is treated selfconsistently. Freshly ejected plume particles are moving in almost circular orbits because the Enceladus orbital speed exceeds the particles' ejection speeds by far. Only a small fraction of grains that leave the Hill sphere of Enceladus survive the next encounter with the moon. Thus, the flux and size distribution of the surviving grains, replenishing the ring particle reservoir, differs significantly from the flux and size distribution of the particles freshly ejected from the plume. Our numerical simulations reproduce the vertical ring profile measured by the Cassini Cosmic Dust Analyzer (CDA) [Kempf, S., Beckmann, U., Moragas-Klostermeyer, G., Postberg, F., Srama, R., EconoDmou, T., Smchmidt, J., Spahn, F., Grün, E., 2008. Icarus 193, 420-437]. From our simulations we calculate the deposition rates of plume particles hitting Enceladus' surface. We find that at a distance of 100 m from a jet a 10 m sized ice boulder should be covered by plume particles in 105- 106 years.

Tree-ring growth patterns and climatic signals along a vertical transect of larch sites in the Simplon and Rhône Valleys (Switzerland)

NASA Astrophysics Data System (ADS)

Riechelmann, Dana F. C.; Esper, Jan

2017-04-01

State-of-the-art millennial long temperature reconstructions from the European Alps integrate wood samples of Larix decidua Mill. from the Lötschental and Simplon regions in Switzerland (Büntgen et al., 2005; 2006). Some of the oldest samples that enable the extension of the time-series back into the first millennium AD are obtained from old buildings in Simplon Village, through the precise location of these samples and the elevation of sampling sites remain unknown. We here evaluate the growth characteristics of larch tree-ring width data along a vertical transect in the Simplon and Rhône valleys. 330 trees from nine sites in 985, 1100, 1400, 1575, 1710, 1712, 1900, 2020, and 2150 m asl have been sampled and analysed for their climate signals. The results indicate a stronger temperature signal in the tree-ring width with increasing elevation. The lower the sites the more a drought signal is imprinted in the ring width data. The intermediate site at 1400 m asl does not show any pronounced climate signal. A comparison of growth patterns of living-tree sites with samples from the historical buildings in Simplon Village (Riechelmann et al., 2013) indicates the construction timber to origin from intermediate to higher elevations. We therefore do not expect strong temperature signal from these timbers. References: Büntgen, U., Esper, J., Frank, D.C., Nicolussi, K., Schmidhalter, M., 2005. A 1052-year tree-ring proxy for Alpine summer temperatures. Climate Dynamics 25: 141-153. Büntgen, U., Frank, D.C., Nievergelt, D., Esper J., 2006. Summer temperature variations in the European Alps, A.D. 755-2004. Journal of Climate 19: 5606-5623. Riechelmann, D.F.C., Schmidhalter, M., Büntgen, U., Esper, J., 2013. Extending a high-elevation larch ring width chronology from the Simplon region in the Swiss Alps over the past millenium. TRACE 11:103-108.

Triple Play

NASA Image and Video Library

2016-01-04

NASA Cassini spacecraft captured Enceladus above the rings and Rhea below. The comparatively tiny speck of Atlas can also be seen just above and to the left of Rhea, and just above the thin line of Saturn F ring.

Eleventh interim status report: Model 9975 O-Ring fixture long-term leak performance

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

Daugherty, W.

2016-08-01

A series of experiments to monitor the aging performance of Viton® GLT O-rings used in the Model 9975 package has been ongoing since 2004 at the Savannah River National Laboratory. One approach has been to periodically evaluate the leak performance of O-rings being aged in mock-up 9975 Primary Containment Vessels (PCVs) at elevated temperature. Other methods such as compression-stress relaxation (CSR) tests and field surveillance are also on-going to evaluate O-ring behavior. Seventy tests using PCV mock-ups were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially and have been tested periodically to determinemore » if they continue to meet the leak-tightness criterion defined in ANSI standard N14.5-97. Due to material substitution, fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF.« less

Tenth interim status report: Model 9975 O-ring fixture long-term leak performance

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

Daugherty, W. L.

2015-08-26

A series of experiments to monitor the aging performance of Viton ® GLT O-rings used in the Model 9975 package has been ongoing since 2004 at the Savannah River National Laboratory. One approach has been to periodically evaluate the leak performance of O-rings being aged in mock-up 9975 Primary Containment Vessels (PCVs) at elevated temperatures. Other methods such as compression-stress relaxation (CSR) tests and field surveillance are also on-going to evaluate O-ring behavior. Seventy tests using PCV mock-ups were assembled and heated to temperatures ranging from 200 to 450 °F. They were leak-tested initially and have been tested periodically tomore » determine if they continue to meet the leak-tightness criterion defined in ANSI standard N14.5-97. Due to material substitution, fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 °F.« less

Effects of Material Combinations on Friction and Wear of PEEK/Steel Pairs under Oil-Lubricated Sliding Contacts

NASA Astrophysics Data System (ADS)

Akagaki, T.; Nakamura, T.; Hashimoto, Y.; Kawabata, M.

2017-05-01

The effects of material combinations on the friction and wear of PEEK/steel pairs are studied using blocks on a ring wear tester under oil-lubricated conditions. The rings are made of forged steel (SF540A) and a PEEK composite filled with 30 wt% carbon fibre. The surface roughness is 0.15 and 0.32 μm Ra, respectively. The blocks are also made of the same materials as the rings: the forged steel and the PEEK composite. Finished with an emery paper of #600, the surface roughness is 0.06 and 0.23 μm Ra, respectively. Sliding tests for 4 combinations of two materials are conducted. The load is increased up to 1177 N at 1 N s-1. The sliding velocity is varied in the range of 10 to 19 m s-1. In some cases, the ring temperature is measured with a thermocouple with a diameter of 0.5 mm, located 1 mm below the frictional surface. Results indicate that the forged steel’s ring and the PEEK composite’s block is the best combination among 4 combinations, because seizure does not occur under the increasing load up to 1177 N at the sliding velocity of 10-19 m s-1. In contrast, seizure occurs at 15 and 19 m s-1 in the other three combinations. However, the PEEK composite’s ring shows a lower friction coefficient as compared to the forged steel’s ring, when seizure does not occur. Wear scars are observed with a scanning electron microscope (SEM). The seizure mechanisms are then discussed.

4-[(E)-(2,4-Difluoro-phen-yl)(hydroxy-imino)meth-yl]piperidinium picrate.

PubMed

Jasinski, Jerry P; Butcher, Ray J; Yathirajan, H S; Mallesha, L; Mohana, K N

2009-09-05

The title compound, C(12)H(15)F(2)N(2)O(+)·C(6)H(2)N(3)O(7) (-), a picrate salt of 4-[(E)-(2,4-difluoro-phen-yl)(hydroxy-imino)meth-yl]piper-idine, crystallizes with two independent mol-ecules in a cation-anion pair in the asymmetric unit. In the cation, a methyl group is tris-ubstituted by hydroxy-imino, piperidin-4-yl and 2,4-difluoro-phenyl groups, the latter of which contains an F atom disordered over two positions in the ring [occupancy ratio 0.631 (4):0.369 (4)]. The mean plane of the hydr-oxy group is in a synclinical conformation nearly orthogonal [N-C-C-C = 72.44 (19)°] to the mean plane of the piperidine ring, which adopts a slightly distorted chair conformation. The dihedral angle between the mean plane of the 2,4-difluoro-phenyl and piperidin-4-yl groups is 60.2 (3)°. In the picrate anion, the mean planes of the two o-NO(2) and single p-NO(2) groups adopt twist angles of 5.7 (2), 25.3 (7) and 8.3 (6)°, respectively, with the attached planar benzene ring. The dihedral angle between the mean planes of the benzene ring in the picrate anion and those in the hydroxy-imino, piperidin-4-yl and 2,4-difluoro-phenyl groups in the cation are 84.9 (7), 78.9 (4) and 65.1 (1)°, respectively. Extensive hydrogen-bond inter-actions occur between the cation-anion pair, which help to establish the crystal packing in the unit cell. This includes dual three-center hydrogen bonds with the piperidin-4-yl group, the phenolate and o-NO(2) O atoms of the picrate anion at different positions in the unit cell, which form separate N-H⋯(O,O) bifurcated inter-molecular hydrogen-bond inter-actions. Also, the hydr-oxy group forms a separate hydrogen bond with a nearby piperidin-4-yl N atom, thus providing two groups of hydrogen bonds, which form an infinite two-dimensional network along (011).

Synthesis and Characterization of Perfluoroalkyl Heterocyclic Elastomers

DTIC Science & Technology

Perfluoroalkyl bibenzoxazole polymers containing a (CF2)8 between heterocyclic rings have been prepared by the reaction of dihydroxybenzidine and...methyl perfluorosebacimidate . Through preparation of this polymer, the basic polymerization system has been significantly improved and polymers with...C. (TGA). Copolymers of dihydroxybenzidine and methyl perfluoro -4,9,14,19- tetraoxadocosanediimidate, which are tacky and resilient, have been

Isometries and binary images of linear block codes over ℤ4 + uℤ4 and ℤ8 + uℤ8

NASA Astrophysics Data System (ADS)

Sison, Virgilio; Remillion, Monica

2017-10-01

Let {{{F}}}2 be the binary field and ℤ2 r the residue class ring of integers modulo 2 r , where r is a positive integer. For the finite 16-element commutative local Frobenius non-chain ring ℤ4 + uℤ4, where u is nilpotent of index 2, two weight functions are considered, namely the Lee weight and the homogeneous weight. With the appropriate application of these weights, isometric maps from ℤ4 + uℤ4 to the binary spaces {{{F}}}24 and {{{F}}}28, respectively, are established via the composition of other weight-based isometries. The classical Hamming weight is used on the binary space. The resulting isometries are then applied to linear block codes over ℤ4+ uℤ4 whose images are binary codes of predicted length, which may or may not be linear. Certain lower and upper bounds on the minimum distances of the binary images are also derived in terms of the parameters of the ℤ4 + uℤ4 codes. Several new codes and their images are constructed as illustrative examples. An analogous procedure is performed successfully on the ring ℤ8 + uℤ8, where u 2 = 0, which is a commutative local Frobenius non-chain ring of order 64. It turns out that the method is possible in general for the class of rings ℤ2 r + uℤ2 r , where u 2 = 0, for any positive integer r, using the generalized Gray map from ℤ2 r to {{{F}}}2{2r-1}.

Heating and scattering of ring-beam distributions by turbulence

NASA Technical Reports Server (NTRS)

Gray, P. C.; Pontius, D. H., Jr.; Matthaeus, W. H.

1995-01-01

Pickup ions in the solar wind are initially are born in ring-beam distributions, i.e. f(v) varies as delta(v(sub perpendicular) - V(sub sw)sin(Theta)) delta(v(sub parallel) - V(sub sw)cos(Theta)), where Theta is the angle between the solar wind velocity and the IMF(Interplanetary Magnetic Field), and V(sub sw) is the solar wind speed. Often the distribution has been presumed to relax to a distribution that is isotropic in Theta and essentially mono-energetic, a shell or a 'bi-spherical distribution.' However solar wind turbulence is capable of heating the ring distribution on the timescale of a few tens of gyroperiods, a timescale not greatly distinct from that required for pitch angle scattering to a shell. To describe this effect, we have performed test-particle studies of the heating/scattering of the ring beam distribution by MHD turbulence, adopting various models for the MHD fluctuations, including slab and fully dynamic 2D and 3D incompressible turbulence. Furthermore, a system composed of a cold ion ring and a background plasma is unstable to several kinetic plasma instabilities. We carried out kinetic simulations of the ring beam distribution, showing that plasma instabilities also rapidly energize and scatter particles. Results will be presented comparing relaxation and heating rates of the ring-beam distribution by the various mechanisms.

Cassini's Ring Grazing and Grand Finale Orbits: Topping Off an Awesome Mission

NASA Astrophysics Data System (ADS)

Edgington, Scott; Spilker, Linda; Coustenis, Athena

2017-04-01

The Cassini-Huygens mission, a joint collaboration between NASA, ESA, and the Italian Space Agency, is in its last year of operations after nearly 13 years in orbit around Saturn. Cassini will send back its final bits of unique data on September 15th, 2017 as it plunges into Saturn's atmosphere, vaporizing and satisfying planetary protection requirements. Before that time Cassini will continue its legacy of exploration and discovery in 2017 and return unique science data provided by orbits taking the spacecraft into unexplored regions near Saturn and its rings. From the new vantage points, Cassini will continue to study seasonal and temporal changes in the system as northern summer solstice approaches. With the exception of one remaining targeted Titan flyby, all of Cassini's close icy satellite flybys, including those of Enceladus, are now completed. In November 2016, Cassini transitioned to a series of orbits with peripases just outside Saturn's F ring. These 20 orbits include close flybys of some tiny ring moons and excellent views of the F ring and Saturn's outer A ring. The 126th and final close flyby of Titan will propel Cassini across Saturn's main rings and into its Grand Finale series of orbits. Cassini's Grand Finale, starting in April 2017, is comprised of 22 orbits at an inclination of 63 degrees. Cassini will repeatedly dive between Saturn's innermost rings and upper atmosphere providing insights into fundamental questions unattainable during the rest of the mission. Cassini will be the first spacecraft to explore this region. These close orbits provide the highest resolution observations of both the rings and Saturn, and direct in-situ sampling of the ring particles, composition, plasma, Saturn's exosphere and the innermost radiation belts. Saturn's gravitational field will be measured to unprecedented accuracy, providing information on the interior structure of the planet, winds in the outer layers of Saturn's atmosphere, and the mass distribution in the rings. Probing the magnetic field will give insight into the nature of the magnetic dynamo, telling us: why the magnetic field is weak; why it exhibits little, if any, axial tilt; and the true rotation rate of the planet. The ion and neutral mass spectrometer will sniff the exosphere and upper atmosphere for molecules that escape the atmosphere itself and water-based molecules originating from the rings. The cosmic dust analyzer will sample the composition of particles from different parts of the main rings. Until the execution of these final orbits, the answers to such new questions will remain mysteries. The science highlights of Cassini's Grand Finale orbits will be discussed. This work was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2017 California Institute of Technology. Government sponsorship is acknowledged.

Crystal structures of 2-[(4,6-di-amino-pyrimidin-2-yl)sulfan-yl]-N-(naphthalen-1-yl)acetamide and 2-[(4,6-di-amino-pyrimidin-2-yl)sulfan-yl]-N-(4-fluoro-phen-yl)acetamide.

PubMed

Subasri, S; Kumar, Timiri Ajay; Sinha, Barij Nayan; Jayaprakash, Venkatesan; Viswanathan, Vijayan; Velmurugan, Devadasan

2017-02-01

The title compounds, C 16 H 15 N 5 OS, (I), and C 12 H 12 FN 5 OS, (II), are [(di-amino-pyrimidine)-sulfan-yl]acetamide derivatives. In (I), the pyrimidine ring is inclined to the naphthalene ring system by 55.5 (1)°, while in (II), the pyrimidine ring is inclined to the benzene ring by 58.93 (8)°. In (II), there is an intra-molecular N-H⋯N hydrogen bond and a short C-H⋯O contact. In the crystals of (I) and (II), mol-ecules are linked by pairs of N-H⋯N hydrogen bonds, forming inversion dimers with R 2 2 (8) ring motifs. In the crystal of (I), the dimers are linked by bifurcated N-H⋯(O,O) and C-H⋯O hydrogen bonds, forming layers parallel to (100). In the crystal of (II), the dimers are linked by N-H⋯O hydrogen bonds, also forming layers parallel to (100). The layers are linked by C-H⋯F hydrogen bonds, forming a three-dimensional architecture.

Coil compression in simultaneous multislice functional MRI with concentric ring slice-GRAPPA and SENSE.

PubMed

Chu, Alan; Noll, Douglas C

2016-10-01

Simultaneous multislice (SMS) imaging is a useful way to accelerate functional magnetic resonance imaging (fMRI). As acceleration becomes more aggressive, an increasingly larger number of receive coils are required to separate the slices, which significantly increases the computational burden. We propose a coil compression method that works with concentric ring non-Cartesian SMS imaging and should work with Cartesian SMS as well. We evaluate the method on fMRI scans of several subjects and compare it to standard coil compression methods. The proposed method uses a slice-separation k-space kernel to simultaneously compress coil data into a set of virtual coils. Five subjects were scanned using both non-SMS fMRI and SMS fMRI with three simultaneous slices. The SMS fMRI scans were processed using the proposed method, along with other conventional methods. Code is available at https://github.com/alcu/sms. The proposed method maintained functional activation with a fewer number of virtual coils than standard SMS coil compression methods. Compression of non-SMS fMRI maintained activation with a slightly lower number of virtual coils than the proposed method, but does not have the acceleration advantages of SMS fMRI. The proposed method is a practical way to compress and reconstruct concentric ring SMS data and improves the preservation of functional activation over standard coil compression methods in fMRI. Magn Reson Med 76:1196-1209, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Seroprevalence of Toxoplasma gondii, Sarcocystis neurona, and Encephalitozoon cuniculi in three species of lemurs from St. Catherines Island, GA, USA.

PubMed

Yabsley, Michael J; Jordan, Carly N; Mitchell, Sheila M; Norton, Terry M; Lindsay, David S

2007-03-15

In the current study, we determined the seroprevalence of Toxoplasma gondii, Sarcocystis neurona, and Encephalitozoon cuniculi in three species of lemurs from St. Catherines Island, Georgia. Serum samples were tested from 52 ring-tailed lemurs (Lemur catta), six blue-eyed black lemurs (Eulemur macaco flavifrons), and four black and white ruffed lemurs (Varecia variegata variegata) using an agglutination assay. Three ring-tailed lemurs (5.8%) were positive for T. gondii (titer of 1:50); one ring-tailed lemur (1.9%) and one black and white ruffed lemur (25%) were positive for S. neurona (titers of 1:1000); and one ring-tailed lemur (1.9%) was positive for E. cuniculi (titer of 1:400). All blue-eyed black lemurs were negative for antibodies to T. gondii, S. neurona, and E. cuniculi. This is the first detection of antibodies to T. gondii in ring-tailed lemurs and antibodies to S. neurona and E. cuniculi in any species of prosimian.

Rho1- and Pkc1-dependent phosphorylation of the F-BAR protein Syp1 contributes to septin ring assembly.

PubMed

Merlini, Laura; Bolognesi, Alessio; Juanes, Maria Angeles; Vandermoere, Franck; Courtellemont, Thibault; Pascolutti, Roberta; Séveno, Martial; Barral, Yves; Piatti, Simonetta

2015-09-15

In many cell types, septins assemble into filaments and rings at the neck of cellular appendages and/or at the cleavage furrow to help compartmentalize the plasma membrane and support cytokinesis. How septin ring assembly is coordinated with membrane remodeling and controlled by mechanical stress at these sites is unclear. Through a genetic screen, we uncovered an unanticipated link between the conserved Rho1 GTPase and its effector protein kinase C (Pkc1) with septin ring stability in yeast. Both Rho1 and Pkc1 stabilize the septin ring, at least partly through phosphorylation of the membrane-associated F-BAR protein Syp1, which colocalizes asymmetrically with the septin ring at the bud neck. Syp1 is displaced from the bud neck upon Pkc1-dependent phosphorylation at two serines, thereby affecting the rigidity of the new-forming septin ring. We propose that Rho1 and Pkc1 coordinate septin ring assembly with membrane and cell wall remodeling partly by controlling Syp1 residence at the bud neck. © 2015 Merlini et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Species-specific Standardisation of Licorice by Metabolomic Profiling of Flavanones and Chalcones

PubMed Central

Simmler, Charlotte; Jones, Tristesse; Anderson, Jeffrey R.; Nikolić, Dejan C.; van Breemen, Richard B.; Soejarto, Djaja D.; Chen, Shao-Nong; Pauli, Guido F.

2014-01-01

Introduction Major phenolics from licorice roots (Glycyrrhiza sp.) are glycosides of the flavanone liquiritigenin (F) and its 2′-hydroxychalcone isomer, isoliquiritigenin (C). As the F and C contents fluctuate between batches of licorice, both quality control and standardisation of its preparations become complex tasks. Objective To characterise the F and C metabolome in extracts from Glycyrrhiza glabra L. and Glycyrrhiza uralensis Fisch. ex DC. by addressing their composition in major F–C pairs and defining the total F:C proportion. Material and methods Three types of extracts from DNA-authenticated samples were analysed by a validated UHPLC/UV method to quantify major F and C glycosides. Each extract was characterised by the identity of major F–C pairs and the proportion of Fs among all quantified Fs:Cs. Results The F and C compositions and proportions were found to be constant for all extracts from a Glycyrrhiza species. All G. uralensis extracts contained up to 2.5 more Fs than G. glabra extracts. Major F–C pairs were B-ring glycosidated in G. uralensis, and A-/B-ring apiosyl-glucosidated in the G. glabra extracts. The F:C proportion was found to be linked to the glycosidation site: the more B-ring F-C glycosides were present, the higher was the final F:C proportion in the extract. These results enable the chemical differentiation of extracts from G. uralensis and G. glabra, which are characterised by total F:C proportions of 8.37:1.63 and 7.18:2.82, respectively. Conclusion Extracts from G. glabra and G. uralensis can be differentiated by their respective F and C compositions and proportions, which are both useful for further standardisation of licorice botanicals. PMID:25859589

Development of Thermal Barriers for Solid Rocket Motor Nozzle Joints

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Dunlap, Patrick H., Jr.

1999-01-01

The Space Shuttle solid rocket motor case assembly joints are sealed using conventional 0-ring seals. The 5500+F combustion gases are kept a safe distance away from the seals by thick layers of insulation. Special joint-fill compounds are used to fill the joints in the insulation to prevent a direct flowpath to the seals. On a number of occasions. NASA has observed in several of the rocket nozzle assembly joints hot gas penetration through defects in the joint- fill compound. The current nozzle-to-case joint design incorporates primary, secondary and wiper (inner-most) 0-rings and polysulfide joint-fill compound. In the current design, 1 out of 7 motors experience hot gas to the wiper 0-ring. Though the condition does not threaten motor safety, evidence of hot gas to the wiper 0-ring results in extensive reviews before resuming flight. NASA and solid rocket motor manufacturer Thiokol are working to improve the nozzle-to-case joint design by implementing a more reliable J-leg design and a thermal barrier, This paper presents burn-resistance, temperature drop, flow and resiliency test results for several types of NASA braided carbon-fiber thermal barriers. Burn tests were performed to determine the time to burn through each of the thermal barriers when exposed to the flame of an oxy-acetylene torch (5500 F), representative of the 5500 F solid rocket motor combustion temperatures. Thermal barriers braided out of carbon fibers endured the flame for over 6 minutes, three times longer than solid rocket motor burn time. Tests were performed on two thermal barrier braid architectures, denoted Carbon-3 and Carbon-6, to measure the temperature drop across and along the barrier in a compressed state when subjected to the flame of an oxyacetylene torch. Carbon-3 and Carbon-6 thermal barriers were excellent insulators causing temperature drops through their diameter of up to a 2800 and 2560 F. respectively. Gas temperature 1/4" downstream of the thermal barrier were within the downstream Viton 0-ring temperature limit of 600 F. Carbon-6 performed extremely well in subscale rocket "char" motor tests when subjected to hot gas at 3200 F for an 11 second rocket firing, simulating the maximum downstream joint cavity fill time. The thermal barrier reduced the incoming hot gas temperature by 2200 F in an intentionally oversized gap defect, spread the incoming jet flow, and blocked hot slag, thereby offering protection to the downstream 0-rings.

Structure-Activity Relationship Study of Ionotropic Glutamate Receptor Antagonist (2S,3R)-3-(3-Carboxyphenyl)pyrrolidine-2-carboxylic Acid.

PubMed

Krogsgaard-Larsen, Niels; Storgaard, Morten; Møller, Charlotte; Demmer, Charles S; Hansen, Jeanette; Han, Liwei; Monrad, Rune N; Nielsen, Birgitte; Tapken, Daniel; Pickering, Darryl S; Kastrup, Jette S; Frydenvang, Karla; Bunch, Lennart

2015-08-13

Herein we describe the first structure-activity relationship study of the broad-range iGluR antagonist (2S,3R)-3-(3-carboxyphenyl)pyrrolidine-2-carboxylic acid (1) by exploring the pharmacological effect of substituents in the 4, 4', or 5' positions and the bioisosteric substitution of the distal carboxylic acid for a phosphonic acid moiety. Of particular interest is a hydroxyl group in the 4' position 2a which induced a preference in binding affinity for homomeric GluK3 over GluK1 (Ki = 0.87 and 4.8 μM, respectively). Two X-ray structures of ligand binding domains were obtained: 2e in GluA2-LBD and 2f in GluK1-LBD, both at 1.9 Å resolution. Compound 2e induces a D1-D2 domain opening in GluA2-LBD of 17.3-18.8° and 2f a domain opening in GluK1-LBD of 17.0-17.5° relative to the structures with glutamate. The pyrrolidine-2-carboxylate moiety of 2e and 2f shows a similar binding mode as kainate. The 3-carboxyphenyl ring of 2e and 2f forms contacts comparable to those of the distal carboxylate in kainate.

NbF{sub 5} and TaF{sub 5}: Assignment of {sup 19}F NMR resonances and chemical bond analysis from GIPAW calculations

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

Biswal, Mamata, E-mail: Mamata.Biswal-Susanta_Kumar_Nayak.Etu@univ-lemans.fr; Body, Monique, E-mail: monique.body@univ-lemans.fr; Legein, Christophe, E-mail: christophe.legein@univ-lemans.fr

2013-11-15

The {sup 19}F isotropic chemical shifts (δ{sub iso}) of two isomorphic compounds, NbF{sub 5} and TaF{sub 5}, which involve six nonequivalent fluorine sites, have been experimentally determined from the reconstruction of 1D {sup 19}F MAS NMR spectra. In parallel, the corresponding {sup 19}F chemical shielding tensors have been calculated using the GIPAW method for both experimental and DFT-optimized structures. Furthermore, the [M{sub 4}F{sub 20}] units of NbF{sub 5} and TaF{sub 5} being held together by van der Waals interactions, the relevance of Grimme corrections to the DFT optimization processes has been evaluated. However, the semi-empirical dispersion correction term introduced bymore » such a method does not show any significant improvement. Nonetheless, a complete and convincing assignment of the {sup 19}F NMR lines of NbF{sub 5} and TaF{sub 5} is obtained, ensured by the linearity between experimental {sup 19}F δ{sub iso} values and calculated {sup 19}F isotropic chemical shielding σ{sub iso} values. The effects of the geometry optimizations have been carefully analyzed, confirming among other matters, the inaccuracy of the experimental structure of NbF{sub 5}. The relationships between the fluorine chemical shifts, the nature of the fluorine atoms (bridging or terminal), the position of the terminal ones (opposite or perpendicular to the bridging ones), the fluorine charges, the ionicity and the length of the M–F bonds have been established. Additionally, for three of the {sup 19}F NMR lines of NbF{sub 5}, distorted multiplets, arising from {sup 1}J-coupling and residual dipolar coupling between the {sup 19}F and {sup 93}Nb nuclei, were simulated yielding to values of {sup 93}Nb–{sup 19}F {sup 1}J-coupling for the corresponding fluorine sites. - Graphical abstract: The complete assignment of the {sup 19}F NMR lines of NbF{sub 5} and TaF{sub 5} allow establishing relationships between the {sup 19}F δ{sub iso} values, the nature of the fluorine atoms (bridging or terminal), the position of the terminal ones (opposite or perpendicular to the bridging ones), the fluorine charges, the ionicity and the length of the M–F bonds. Display Omitted - Highlights: • The {sup 19}F δ{sub iso} values of NbF{sub 5} and TaF{sub 5} have been determined. • The {sup 19}F chemical shielding tensors have been calculated using the GIPAW method. • A confident assignment of the {sup 19}F NMR lines of NbF{sub 5} and TaF{sub 5} is obtained. • The relationships between the {sup 19}Fδ{sub iso} values and the M–F bonds features are established.« less

Design and construction of a novel 1H/19F double-tuned coil system using PIN-diode switches at 9.4T.

PubMed

Choi, Chang-Hoon; Hong, Suk-Min; Ha, YongHyun; Shah, N Jon

2017-06-01

A double-tuned 1 H/ 19 F coil using PIN-diode switches was developed and its performance evaluated. The is a key difference from the previous developments being that this design used a PIN-diode switch in series with an additionally inserted inductor in parallel to one of the capacitors on the loop. The probe was adjusted to 19 F when the reverse bias voltage was applied (PIN-diode OFF), whilst it was switched to 1 H when forward current was flowing (PIN-diode ON). S-parameters and Q-factors of single- and double-tuned coils were examined and compared with/without a phantom on the bench. Imaging experiments were carried out on a 9.4T preclinical scanner. All coils were tuned at resonance frequencies and matched well. It is shown that the Q-ratio and SNR of double-tuned coil at 19 F frequency are nearly as good as those of a single-tuned coil. Since the operating frequency was tuned to 19 F when the PIN-diodes were turned off, losses due to PIN-diodes were substantially lower resulting in the provision of excellent image quality of X-nuclei. Copyright © 2017 Elsevier Inc. All rights reserved.

Synthesis and Characterization of a Magnetically Active 19F Molecular Beacon.

PubMed

Dempsey, Megan E; Marble, Hetal D; Shen, Tun-Li; Fawzi, Nicolas L; Darling, Eric M

2018-02-21

Gene expression is used extensively to describe cellular characteristics and behaviors; however, most methods of assessing gene expression are unsuitable for living samples, requiring destructive processes such as fixation or lysis. Recently, molecular beacons have become a viable tool for live-cell imaging of mRNA molecules in situ. Historically, beacon-mediated imaging has been limited to fluorescence-based approaches. We propose the design and synthesis of a novel molecular beacon for magnetic resonance detection of any desired target nucleotide sequence. The biologically compatible synthesis incorporates commonly used bioconjugation reactions in aqueous conditions and is accessible for laboratories without extensive synthesis capabilities. The resulting beacon uses fluorine ( 19 F) as a reporter, which is broadened, or turned "off", via paramagnetic relaxation enhancement from a stabilized nitroxide radical spin label when the beacon is not bound to its nucleic acid target. Therefore, the 19 F NMR signal of the beacon is quenched in its hairpin conformation when the spin label and the 19 F substituent are held in proximity, but the signal is recovered upon beacon hybridization to its specific complementary nucleotide sequence by physical separation of the radical from the 19 F reporter. This study establishes a path for magnetic resonance-based assessment of specific mRNA expression, providing new possibilities for applying molecular beacon technology in living systems.

18,21-Anhydroaldosterone and derivatives.

PubMed

Harnik, M; Kashman, Y; Cojocaru, M; Lewicka, S; Vecsei, P

1989-07-01

18,21-Anhydroaldosterone 8, 18,21-anhydro-19-noraldosterone 9, and 3 alpha, 5 beta-tetrahydro-18,21-anhydro-19-noraldosterone 13, which may be present in acid-processed urine, were prepared by cleaving their 20-ketal derivatives 2, 3, and 12 with hot mineral acid. Compounds 8 and 9 were also made by direct dehydration of aldosterone 5 and 19-noraldosterone 10 in good yield. The reverse ring opening of 8 to 5 could be carried out in moderate yield with an acetic acid-acetic anhydride-perchloric acid mixture, while an analogous ring opening of 9 gave only a poor yield of 10.

Applications of Molecular Modeling to Transition State Energies and Conformations

DTIC Science & Technology

1992-05-08

reactivity trends for similar systems are known. Illuminati and Mandolini have done research on the lactone formation from w-bromoalkane-carboxylate...strikingly similar to that determined for Illuminati and Mandolini’s similar lactonization system (see Figure 20). The AE, for the 4- 69 membered ring...Brown, F.K.; Spellmeyer, D.C.; Metz, J.T.; Li, Y.; Loncharich, R.L. Science. 1986, 231, 1108-17. Illuminati , G.; Mandolini, L. Accts. of Chem. Res. 1981

Rapid Response Research and Development (R&D) for the Aerospace Systems Directorate. Delivery Order 0004: Research for Propulsion and Power Systems. Volume 2 - Students Exploring Advanced Technologies (SEAT) Program

DTIC Science & Technology

2014-09-01

Marshall “ Wind Turbines and Energy” • Eugene Whatley 12th Grade T. Marshall “Acceleration of Battery-Powered cars on Different Surfaces” • Jhaelynn...There were several mini-demos including: making a model for wind tunnel, egg carton gliders, and ring wing gliders. C3.3 Robotics Team The...115 F3.6 WHAT ARE WIND TUNNELS

New Way of Characterizing the State of the Ring Current

NASA Astrophysics Data System (ADS)

Wolf, R.; Bao, S.; Gkioulidou, M.; Yang, J.; Toffoletto, F.

2017-12-01

The flux tube entropy S is invariant in ideal MHD and is a good way to characterize the degree to which a closed flux tube is loaded with particle energy. Flux tube entropy generally increases with increasing geocentric distance. A flux tube that is injected from the plasma sheet into the ring current tends to be a bubble that has a lower S value than typical plasma sheet flux tubes, and it tends to penetrate to a position where the surroundings matches its S. From this point of view, a good way to characterize the state of the ring current is through the function dF/dS, which specifies how much magnetic flux is occupied by tubes with different degrees of loading. By displaying dF/dS curves before and during storm main phases simulated with the RCM-E code, we determine that, in the model, the injection of the stormtime ring current consists of replacing pre-storm low-S flux tubes with tubes from the plasma sheet that have a certain limited range of S, which is well below typical plasma-sheet values. We also display dF/dS curves for passes by the Van Allen Probes before and during storm main phases, and compare with the RCM-E-derived curves, to gain insight into the nature of the flux tubes that are injected to form the real storm-time ring current.

Dimethandrolone (7α,11β-dimethyl-19-nortestosterone) and 11β-methyl-19-nortestosterone are not converted to aromatic A-ring products in the presence of recombinant human aromatase☆

PubMed Central

Attardi, Barbara J.; Pham, Trung C.; Radler, Lisa M.; Burgenson, Janet; Hild, Sheri A.; Reel, Jerry R.

2008-01-01

Dimethandrolone undecanoate (DMAU: 7α,11β-dimethyl-19-nortestosterone 17β-undecanoate) is a potent orally active androgen in development for hormonal therapy in men. Cleavage of the 17β-ester bond by esterases in vivo leads to liberation of the biologically active androgen, dimethandrolone (DMA), a 19-norandrogen. For hormone replacement in men, administration of C19 androgens such as testosterone (T) may lead to elevations in circulating levels of estrogens due to aromatization. As several reports have suggested that certain 19-norandrogens may serve as substrates for the aromatase enzyme and are converted to the corresponding aromatic A-ring products, it was important to investigate whether DMA, the related compound, 11β-methyl-19-nortestosterone (11β-MNT), also being tested for hormonal therapy in men, and other 19-norandrogens can be converted to aromatic A-ring products by human aromatase. The hypothetical aromatic A-ring product corresponding to each substrate was obtained by chemical synthesis. These estrogens bound with high affinity to purified recombinant human estrogen receptors (ER) α and β in competitive binding assays (IC50's: 5−12 × 10−9 M) and stimulated transcription of 3XERE-luciferase in T47Dco human breast cancer cells with a potency equal to or greater than that of estradiol (E2) (EC50's: 10−12 to 10−11 M). C19 androgens (T, 17α-methyltestosterone (17α-MT), androstenedione (AD), and 16α-hydroxyandrostenedione (16α-OHAD)), 19-norandrogens (DMA, 11β-MNT, 19-nortestosterone (19-NT), and 7α-methyl-19-nortestosterone (MENT)) or the structurally similar 19-norprogestin, norethindrone (NET) were incubated at 50 μM with recombinant human aromatase for 10−180 min at 37 °C. The reactions were terminated by extraction with acetonitrile and centrifugation, and substrate and potential product were separated by HPLC. Retention times were monitored by UV absorption, and UV peaks were quantified using standard curves. Aromatization of the positive controls, T, AD, and 16α-OHAD was linear for 40−60 min, and conversion of T or AD was complete by 120 min. The nonsteroidal aromatase inhibitor, letrozole, demonstrated concentration-dependent suppression of T aromatization. Under the same conditions, there was no detectable conversion of DMA, 11β-MNT, or NET to their respective hypothetical aromatic A-ring products during incubation times up to 180 min. Aromatization of MENT and 19-NT proceeded slowly and was limited. Collectively, these data support the notion that in the absence of the C19-methyl group, which is the site of attack by oxygen, aromatization of androgenic substrates proceeds slowly or not at all and that this reaction is impeded by the presence of a methyl group at the 11β position. PMID:18555683

Saturn Ring

NASA Image and Video Library

2007-12-12

Like Earth, Saturn has an invisible ring of energetic ions trapped in its magnetic field. This feature is known as a "ring current." This ring current has been imaged with a special camera on Cassini sensitive to energetic neutral atoms. This is a false color map of the intensity of the energetic neutral atoms emitted from the ring current through a processed called charged exchange. In this process a trapped energetic ion steals and electron from cold gas atoms and becomes neutral and escapes the magnetic field. The Cassini Magnetospheric Imaging Instrument's ion and neutral camera records the intensity of the escaping particles, which provides a map of the ring current. In this image, the colors represent the intensity of the neutral emission, which is a reflection of the trapped ions. This "ring" is much farther from Saturn (roughly five times farther) than Saturn's famous icy rings. Red in the image represents the higher intensity of the particles, while blue is less intense. Saturn's ring current had not been mapped before on a global scale, only "snippets" or areas were mapped previously but not in this detail. This instrument allows scientists to produce movies (see PIA10083) that show how this ring changes over time. These movies reveal a dynamic system, which is usually not as uniform as depicted in this image. The ring current is doughnut shaped but in some instances it appears as if someone took a bite out of it. This image was obtained on March 19, 2007, at a latitude of about 54.5 degrees and radial distance 1.5 million kilometres (920,000 miles). Saturn is at the center, and the dotted circles represent the orbits of the moon's Rhea and Titan. The Z axis points parallel to Saturn's spin axis, the X axis points roughly sunward in the sun-spin axis plane, and the Y axis completes the system, pointing roughly toward dusk. The ion and neutral camera's field of view is marked by the white line and accounts for the cut-off of the image on the left. The image is an average of the activity over a (roughly) 3-hour period. http://photojournal.jpl.nasa.gov/catalog/PIA10094

­Back-to-back mechanisms drive actomyosin ring closure during Drosophila embryo cleavage

PubMed Central

2016-01-01

Contraction of actomyosin rings during cytokinesis is typically attributed to actin filaments sliding toward each other via Myosin-2 motor activity. However, rings constrict in some cells in the absence of Myosin-2 activity. Thus, ring closure uses Myosin-2–dependent and –independent mechanisms. But what the Myosin-2–independent mechanisms are, and to what extent they are sufficient to drive closure, remains unclear. During cleavage in Drosophila melanogaster embryos, actomyosin rings constrict in two sequential and mechanistically distinct phases. We show that these phases differ in constriction speed and are genetically and pharmacologically separable. Further, Myosin-2 activity is required for slow constriction in “phase 1” but is largely dispensable for fast constriction in “phase 2,” and F-actin disassembly is only required for fast constriction in phase 2. Switching from phase 1 to phase 2 seemingly relies on the spatial organization of F-actin as controlled by Cofilin, Anillin, and Septin. Our work shows that fly embryos present a singular opportunity to compare separable ring constriction mechanisms, with varying Myosin-2 dependencies, in one cell type and in vivo. PMID:27799369

Ring-diameter Ratios for Multi-ring Basins Average 2.0(0.5)D

NASA Technical Reports Server (NTRS)

Pike, R. J.; Spudis, P. D.

1985-01-01

The spacing of the concentric rings of planetary impact basins was studied. It is shown that a radial increment of x (sup 0.5) D, where x is about 2.0 and D = ring diameter, separates both (1) adjacent least-squares groups of rings and arcs of multi-ring basins on Mars, Mercury, and the Moon; and (2) adjacent rings of individual basins on the three planets. Statistics for ratios of ring diameters are presented, the first and most-applied parameter of ring spacing. It is found that ratios excluding rings flanking the main ring also have a mean spacing increment of about 2.0. Ratios including such rings, as for the least-squares groups, and (1) above, have a larger increment, averaging 2.1. The F-test indicates, that these spacings of basin ring locations, and mode of ring formation are controlled by the mechanics of the impact event itself, rather than by crustal properties.

Expansion and concatenation of nonmuscle myosin IIA filaments drive cellular contractile system formation during interphase and mitosis

PubMed Central

Fenix, Aidan M.; Taneja, Nilay; Buttler, Carmen A.; Lewis, John; Van Engelenburg, Schuyler B.; Ohi, Ryoma; Burnette, Dylan T.

2016-01-01

Cell movement and cytokinesis are facilitated by contractile forces generated by the molecular motor, nonmuscle myosin II (NMII). NMII molecules form a filament (NMII-F) through interactions of their C-terminal rod domains, positioning groups of N-terminal motor domains on opposite sides. The NMII motors then bind and pull actin filaments toward the NMII-F, thus driving contraction. Inside of crawling cells, NMIIA-Fs form large macromolecular ensembles (i.e., NMIIA-F stacks), but how this occurs is unknown. Here we show NMIIA-F stacks are formed through two non–mutually exclusive mechanisms: expansion and concatenation. During expansion, NMIIA molecules within the NMIIA-F spread out concurrent with addition of new NMIIA molecules. Concatenation occurs when multiple NMIIA-Fs/NMIIA-F stacks move together and align. We found that NMIIA-F stack formation was regulated by both motor activity and the availability of surrounding actin filaments. Furthermore, our data showed expansion and concatenation also formed the contractile ring in dividing cells. Thus interphase and mitotic cells share similar mechanisms for creating large contractile units, and these are likely to underlie how other myosin II–based contractile systems are assembled. PMID:26960797

NbF5 and TaF5: Assignment of 19F NMR resonances and chemical bond analysis from GIPAW calculations

NASA Astrophysics Data System (ADS)

Biswal, Mamata; Body, Monique; Legein, Christophe; Sadoc, Aymeric; Boucher, Florent

2013-11-01

The 19F isotropic chemical shifts (δiso) of two isomorphic compounds, NbF5 and TaF5, which involve six nonequivalent fluorine sites, have been experimentally determined from the reconstruction of 1D 19F MAS NMR spectra. In parallel, the corresponding 19F chemical shielding tensors have been calculated using the GIPAW method for both experimental and DFT-optimized structures. Furthermore, the [M4F20] units of NbF5 and TaF5 being held together by van der Waals interactions, the relevance of Grimme corrections to the DFT optimization processes has been evaluated. However, the semi-empirical dispersion correction term introduced by such a method does not show any significant improvement. Nonetheless, a complete and convincing assignment of the 19F NMR lines of NbF5 and TaF5 is obtained, ensured by the linearity between experimental 19F δiso values and calculated 19F isotropic chemical shielding σiso values. The effects of the geometry optimizations have been carefully analyzed, confirming among other matters, the inaccuracy of the experimental structure of NbF5. The relationships between the fluorine chemical shifts, the nature of the fluorine atoms (bridging or terminal), the position of the terminal ones (opposite or perpendicular to the bridging ones), the fluorine charges, the ionicity and the length of the M-F bonds have been established. Additionally, for three of the 19F NMR lines of NbF5, distorted multiplets, arising from 1J-coupling and residual dipolar coupling between the 19F and 93Nb nuclei, were simulated yielding to values of 93Nb-19F 1J-coupling for the corresponding fluorine sites.

Planetary Rings: a Brief History of Observation and Theory

NASA Astrophysics Data System (ADS)

Nicholson, P. D.

2000-05-01

Over several centuries, and extending down to today, the ring systems encircling Saturn and the other jovian planets have provided an endless source of speculation and theorizing for astronomers, theologians, and physicists. In the past two decades they have also become a testing ground for dynamical models of more distant astrophysical disks, such as those which surround protostars and even the stellar disks of spiral galaxies. I will review some of the early theories, and their sometimes rude confrontation with observational data, starting with Christiaan Huygens and touching on seminal contributions by Laplace, Bessel, Maxwell, Barnard, Russell (of H-R diagram fame) and Jeffreys. In the modern era, observations at infrared and radio wavelengths have revealed Saturn's rings to be composed of large chunks of almost pure water ice, and to have a vertical thickness measured in tens of meters. A renaissance in planetary rings studies occurred in the period 1977--1981, first with the discoveries of the narrow, dark and non-circular rings of Uranus and the tenuous jovian ring system, and capped off by the spectacular images returned during the twin Voyager flybys of Saturn. Along with the completely unsuspected wealth of detail these observations revealed came an unwelcome problem: are the rings ancient or are we privileged to live at a special time in history? The answer to this still-vexing question may lie in the complex gravitational interactions recent studies have revealed between the rings themselves and their retinues of attendant satellites. Between the four known ring systems, we see elegant examples of Lindblad and corotation resonances (first invoked in the galactic context), electromagnetic resonances, many-armed spiral density waves and bending waves, narrow ringlets which exhibit internal modes due to a collective instability, sharp-edged gaps maintained via tidal torques from embedded moonlets, and tenuous dust belts created by meteoroid impact onto parent bodies. I will conclude with a glimpse at what may well be a dynamicist's worst nightmare --- Saturn's multi-stranded, kinky and clumpy F ring, which continues to puzzle 20 years after it was first seen. The author would like to acknowledge many discussions with Joe Burns, Jeff Cuzzi, Luke Dones, Jim Elliot, Dick French, Peter Goldreich, Mark Showalter and Bruno Sicardy, as well as generous support from NASA.

Endophytic Diaporthe sp. LG23 Produces a Potent Antibacterial Tetracyclic Triterpenoid.

PubMed

Li, Gang; Kusari, Souvik; Kusari, Parijat; Kayser, Oliver; Spiteller, Michael

2015-08-28

A new lanostanoid, 19-nor-lanosta-5(10),6,8,24-tetraene-1α,3β,12β,22S-tetraol (1), characterized by the presence of an aromatic B ring and hydroxylated at C-1, C-3, C-12, and C-22, was isolated from an endophytic fungus, Diaporthe sp. LG23, inhabiting leaves of the Chinese medicinal plant Mahonia fortunei. Six biosynthetically related known steroids were also isolated in parallel. Their structures were confirmed on the basis of detailed spectroscopic analysis in conjunction with the published data. Compound 1, an unusual fungus-derived 19-nor-lanostane tetracyclic triterpenoid with an aromatic B-ring system, exhibited pronounced antibacterial efficacy against both Gram-positive and -negative bacteria, especially the clinical isolates of Streptococcus pyogenes and Pseudomonas aeruginosa as well as a human pathogenic strain of Staphylococcus aureus. Our results reveal the potential of endophytes not only in conferring host fitness but also in contributing toward traditional host plant medicines.

Numerical evaluation of single central jet for turbine disk cooling

NASA Astrophysics Data System (ADS)

Subbaraman, M. R.; Hadid, A. H.; McConnaughey, P. K.

The cooling arrangement of the Space Shuttle Main Engine High Pressure Oxidizer Turbopump (HPOTP) incorporates two jet rings, each of which produces 19 high-velocity coolant jets. At some operating conditions, the frequency of excitation associated with the 19 jets coincides with the natural frequency of the turbine blades, contributing to fatigue cracking of blade shanks. In this paper, an alternate turbine disk cooling arrangement, applicable to disk faces of zero hub radius, is evaluated, which consists of a single coolant jet impinging at the center of the turbine disk. Results of the CFD analysis show that replacing the jet ring with a single central coolant jet in the HPOTP leads to an acceptable thermal environment at the disk rim. Based on the predictions of flow and temperature fields for operating conditions, the single central jet cooling system was recommended for implementation into the development program of the Technology Test Bed Engine at NASA Marshall Space Flight Center.

Dispersion Forces and the Molecular Origin of Internal Friction in Protein.

PubMed

Sashi, Pulikallu; Ramakrishna, Dasari; Bhuyan, Abani K

2016-08-23

Internal friction in macromolecules is one of the curious phenomena that control conformational changes and reaction rates. It is held here that dispersion interactions and London-van der Waals forces between nonbonded atoms are major contributors to internal friction. To demonstrate this, the flipping motion of aromatic rings of F10 and Y97 amino acid residues of cytochrome c has been studied in glycerol/water mixtures by cross relaxation-suppressed exchange nuclear magnetic resonance spectroscopy. The ring-flip rate is highly overdamped by glycerol, but this is not due to the effect of protein-solvent interactions on the Brownian dynamics of the protein, because glycerol cannot penetrate into the protein to slow the internal collective motions. Sound velocity in the protein under matching solvent conditions shows that glycerol exerts its effect by rather smothering the protein interior to produce reduced molecular compressibility and root-mean-square volume fluctuation (δVRMS), implying an increased number of dispersion interactions of nonbonded atoms. Hence, δVRMS can be used as a proxy for internal friction. By using the ansatz that internal friction is related to nonbonded interactions by the equation f(n) = f0 + f1n + f2n(2) + ..., where the variable n is the extent of nonbonded interactions with fi coefficients, the barrier to aromatic ring rotation is found to be flat. Also interesting is the appearance of a turnover region in the δVRMS dependence of the ring-flip rate, suggesting anomalous internal diffusion. We conclude that cohesive forces among nonbonded atoms are major contributors to the molecular origin of internal friction.

Appearance of Saturn’s F ring azimuthal channels for the anti-alignment configuration between the ring and Prometheus

NASA Astrophysics Data System (ADS)

Chavez, Carlos E.

2009-09-01

In this article we explore the aspect of the F ring with respect to the anti-alignment configuration between the ring and Prometheus. We focus our attention on the shape of the F ring's azimuthal channels which were first reported by Porco et al. (Porco, C.C., Baker, E., Barbara, J., Beurle, K., Brahic, A., Burns, J.A., Charnoz, S., Cooper, N., Dawson, D.D., Del Genio, A.D., Denk, T., Dones, L., Dyudina, U., Evans, M.W., Giese, B., Grazier, K., Helfenstein, P., Ingersoll, A.P., Jacobson, R.A., Johnson, T.V., McEwen, A., Murray, C.D., Neukum, G., Owen, W.M., Perry, J., Roatsch, T., Spitale, J., Squyres, S., Thomas, P., Tiscareno, M., Turtle, E., Vasavada, A.R., Veverka, J., Wagner, R., West, R. [2005] Science, 307, 1226-1236) and numerically explored by Murray et al. (Murray, C.D., Chavez, C., Beurle, K., Cooper, N., Evans, M.W., Burns, J.A., Porco, C.C. [2005] Nature 437, 1326-1329) who found excellent agreement between Cassini's ISS reprojected images and their numerical model via a direct comparison. We find that for anti-alignment the channels are wider and go deeper inside the ring material. From our numerical model we find a new feature, an island in the middle of the channel. This island is made up of the particles that have been perturbed the most by Prometheus and only appears when this satellite is close to apoapsis. In addition, plots of the anti-alignment configuration for different orbital stages of Prometheus are obtained and discussed here.

Stability of the prosthetic screws of three types of craniofacial prostheses retention systems

PubMed Central

2016-01-01

Objectives This study aimed to evaluate the stability of prosthetic screws from three types of craniofacial prostheses retention systems (bar-clip, ball/O-ring, and magnet) when submitted to mechanical cycling. Materials and Methods Twelve models of acrylic resin were used with implants placed 20 mm from each other and separated into three groups: (1) bar-clip (Sistema INP, São Paulo, Brazil), (2) ball/O-ring (Sistema INP), and (3) magnet (Metalmag, São Paulo, Brazil), with four samples in each group. Each sample underwent a mechanical cycling removal and insertion test (f=0.5 Hz) to determine the torque and the detorque values of the retention screws. A servo-hydraulic MTS machine (810-Flextest 40; MTS Systems, Eden Prairie, MN, USA) was used to perform the cycling with 2.5 mm and a displacement of 10 mm/s. The screws of the retention systems received an initial torque of 30 Ncm and the torque values required for loosening the screw values were obtained in three cycles (1,080, 2,160, and 3,240). The screws were retorqued to 30 Ncm before each new cycle. Results The sample was composed of 24 screws grouped as follows: bar-clip (n=8), ball/O-ring (n=8), and magnet (n=8). There were significant differences between the groups, with greater detorque values observed in the ball/O-ring group when compared to the bar-clip and magnet groups for the first cycle. However, the detorque value was greater in the bar-clip group for the second cycle. Conclusion The results of this study indicate that all prosthetic screws will loosen slightly after an initial tightening torque, also the bar-clip retention system demonstrated greater loosening of the screws when compared with ball/O-ring and magnet retention systems. PMID:28053905

Dynamical Models of the Solar System Formation and Evolution

NASA Technical Reports Server (NTRS)

Stewart, Glen R.

2002-01-01

Mark Lewis has extended his them is work by completing a series of N-body simulations of a narrow ring that: is in the location of Saturn's F-ring and is perturbed by a single satellite comparable to Prometheus, but on a circular orbit. We had previously shown how the satellite perturbations can cause a broadly distributed sparse population of ring particles to become concentrated into narrow rings that can be maintained outside of any resonance location. For low optical depths, the collisions between ring particles are highly localized in the peaks of the satellite wakes. The inelastic collisions therefore occur at a particular orbital phase angle so as to damp the azimuthal component of the relative velocities. Since particle positions are not changed by collisions, the semimajor axes of the particles are shifted toward the actual particle positions where the collisions occur. Thus, negative radial diffusion can occur while conserving orbital angular momentum so long as the forced eccentricity is continually re-excited by the satellite. We speculated that the separation between the final ringlets was largely determined by the magnitude of the forced eccentricities induced by the satellite at closest approach. We carried out a series of simulations with a variety of different satellite masses in order to vary the magnitude of the forced eccentricity. We found that indeed the final spacing of the ringlets does increase with the magnitude of the forced eccentricity (Lewis and Stewart 2002). This occurs because neighboring eccentric ringlets drift out of phase with one another due to Keplerian shear and eventually collide with one another, leading to a smaller number of more widely spaced ringlets, The time scale required to form narrow ringlets in these simulations is much shorter than one would expect from standard theories based upon the orbit-averaged torque produced by multiple passes by the satellite. We find that the initial ringlets form in less than two synodic periods and the final state is typically reached in 10 to 20 synodic periods. These studies move us closer to understanding the significantly more complex system of Saturn's F ring, where the perturbation magnitude varies over short temporal and spatial time scales due to the orbital eccentricities of the perturbing satellite. We are currently extending the simulation to allow for an eccentric orbit of the satellite.

Saturn's Rings

NASA Astrophysics Data System (ADS)

Cuzzi, J. N.

2014-12-01

The rings are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major ring science progress over the mission to date, and describe new observations planned for Cassini's final three years. Ring Composition and particle sizes: The rings are nearly all water ice with no other ices - so why are they reddish? The C Ring and Cassini Division are "dirtier" than the more massive B and A Rings, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. Ring structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main ring divisions, the C Ring plateau structures, and the B Ring irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A ring. Rubble pile ringmoons just outside the rings may escaped from the rings, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the rings: Comet fragments set the rings to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the Rings: The ring mass and bombardment play key roles. The ring mass is well known everywhere but in the B Ring (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient rings, of which the current ring is just a shadow. During its last three years, the Cassini tour profile will allow entirely new observations: direct measurement of the still-unknown ring mass; direct in-situ sampling of ring particle composition (targeting the iron- or carbon-based red nonicy component); and radar backscattering observations. Cuzzi, J. N. et al. (2010) An Evolving View of Saturn's Dynamic Rings; Science (Inv. Review) 19 March 2010: 327. no. 5972, pp. 1470 - 1475

The variations in eccentricity and apse precession rate of a narrow ring perturbed by a close satellite

NASA Technical Reports Server (NTRS)

Borderies, N.; Goldreich, P.; Tremaine, S.

1983-01-01

The first-order perturbations of orbital eccentricity and apse precession rate for the case of a narrow ring, due to a close satellite whose orbit is also eccentric, are described by means of a Hamiltonian. The present treatment covers cases in which the satellite crosses the ring, and the level curves of the Hamiltonian are displayed for several parameter values. The results obtained are applied to the interaction of Saturn's F ring with its inner shepherd satellite.

u-Constacyclic codes over F_p+u{F}_p and their applications of constructing new non-binary quantum codes

NASA Astrophysics Data System (ADS)

Gao, Jian; Wang, Yongkang

2018-01-01

Structural properties of u-constacyclic codes over the ring F_p+u{F}_p are given, where p is an odd prime and u^2=1. Under a special Gray map from F_p+u{F}_p to F_p^2, some new non-binary quantum codes are obtained by this class of constacyclic codes.

4-[(1E)-3-(2,6-Dichloro-3-fluoro-phen-yl)-3-oxoprop-1-en-1-yl]benzonitrile.

PubMed

Praveen, Aletti S; Yathirajan, Hemmige S; Narayana, Badiadka; Gerber, Thomas; Hosten, Eric; Betz, Richard

2012-05-01

In the title mol-ecule, C(16)H(8)Cl(2)FNO, the benzene rings form a dihedral angle of 78.69 (8)°. The F atom is disordered over two positions in a 0.530 (3):0.470 (3) ratio. The crystal packing exhibits π-π inter-actions between dichloro-substituted rings [centroid-centroid distance = 3.6671 (10) Å] and weak inter-molecular C-H⋯F contacts.

Space shuttle Production Verification Motor 1 (PV-1) static fire

NASA Technical Reports Server (NTRS)

1989-01-01

All inspection and instrumentation data indicate that the PV-1 static test firing conducted 18 Aug. 1988 was successful. With the exception of the intentionally flawed joints and static test modifications, PV-1 was flight configuration. Fail-safe flaws guaranteeing pressure to test the sealing capability of primary O-rings were included in the aft field joint, case-to-nozzle joint, and nozzle internal Joint 5. The test was conducted at ambient conditions, with the exception of the field joints and case/nozzle joints which were maintained at a minimum of 75 F. Ballistics performance values were within specification requirements. The PV-1 motor exhibited chamber pressure oscillations similar to previously tested Space Shuttle redesigned solid rocket motors, particularly QM-7. The first longitudinal mode oscillations experienced by PV-1 were the strongest ever measured in a Space Shuttle motor. Investigation into this observation is being conducted. Joint insulation performed as designed with no evidence of gas flow within unflawed forward field joints. The intentionally flawed center and aft case field joint insulation performance was excellent. There was no evidence of hot gas past the center field joint capture feature O-ring, the case-to-nozzle joint primary O-ring, or the aft field joint primary O-ring. O-ring seals and barriers with assured pressure at the flaws showed erosion and heat effect, but all sealed against passage of hot gases with the exception of the aft field joint capture feature O-ring. There was no evidence of erosion, heat effect, or blowby on any O-ring seals or barriers at the unflawed joints. Nozzle performance was nominal with typical erosion. Post-test examination revealed that the forward nose ring was of the old high performance motor design configuration with the 150-deg ply angle. All nozzle components remained intact for post-test evaluation. The thrust vector control system operated correctly. The water deluge system, CO2 quench, and other test equipment performed as planned during all required test operations.

11-year cycle solar modulation of cosmic ray intensity inferred from C-14 content variation in dated tree rings

NASA Technical Reports Server (NTRS)

Fan, C. Y.; Chen, T. M.; Yun, S. X.; Dai, K. M.

1983-01-01

A liquid scintillation-photomultiplier tube counter system was used to measure the Delta-C-14 values of 60 tree rings, dating from 1866 to 1925, that were taken from a white spruce grown in Canada at 68 deg N, 130 deg W. A 10-percent variation is found which is anticorrelated with sunspot numbers, although the amplitude of the variation is 2-3 times higher than expected in trees grown at lower latitudes. A large dip in the data at about 1875 suggests an anomalously large modulation of cosmic ray intensity during the 1867-1878 AD solar cycle, which was the most active of the 19th century.

Fraction of boroxol rings in vitreous boron oxide from a first-principles analysis of Raman and NMR spectra.

PubMed

Umari, P; Pasquarello, Alfredo

2005-09-23

We determine the fraction f of B atoms belonging to boroxol rings in vitreous boron oxide through a first-principles analysis. After generating a model structure of vitreous B2O3 by first-principles molecular dynamics, we address a large set of properties, including the neutron structure factor, the neutron density of vibrational states, the infrared spectra, the Raman spectra, and the 11B NMR spectra, and find overall good agreement with corresponding experimental data. From the analysis of Raman and 11B NMR spectra, we yield consistently for both probes a fraction f of approximately 0.75. This result indicates that the structure of vitreous boron oxide is largely dominated by boroxol rings.

1,5-Bis(penta­fluoro­phen­yl)-3-phenyl­pent-2-ene-1,5-dione

PubMed Central

Schwarzer, Anke; Weber, Edwin

2009-01-01

In the title compound, C23H8F10O2, the three arene rings are twisted one with respect to the other: the two perfluorinated arene rings are tilted to each other by an angle of 60.39 (7)°. They are inclined to the non-fluorinated phenyl unit by 38.85 (7) and 78.74 (7)°. The olefinic double bond adopts an E configuration. The carbonyl groups are not in a coplanar alignment with reference to the neighbouring arene rings. The crystal packing features a number of weak C—H⋯F inter­actions, which leads to the formation of a three-dimensional network. PMID:21578393

Crystal structure of 1-iodo-3-{[4-(tert-butyl­sulfan­yl)phen­yl]ethyn­yl}azulene

PubMed Central

Förster, Sebastian; Seichter, Wilhelm; Weber, Edwin

2015-01-01

The title compound, C20H19IS, features a 1,3-disubstituted azulene involving an ethynylene elongated 4-(tert-butyl­sulfanyl)­phenyl sidearm and an iodine atom as the substituents. The azulene ring system is almost planar (r.m.s. deviation = 0.012 Å) and subtends a dihedral angle of 35.7 (1)° with the benzene ring. As a result of the inherent dipole character of the azulene core, a supra­molecular π–π dimer [separation between the centroids of the five- and seven-membered rings = 3.7632 (10) Å] with anti­parallel orientated mol­ecules can be observed in the crystal. The packing is consolidated by an unusual I⋯π(acetyl­ene) contact [I⋯Cg = 3.34 Å, C—I⋯Cg = 173.3°], and a very weak C—H⋯π inter­action is also found in the structure, with the azulene five-membered ring as the acceptor. PMID:26396788

A new method for computing the reliability of consecutive k-out-of-n:F systems

NASA Astrophysics Data System (ADS)

Gökdere, Gökhan; Gürcan, Mehmet; Kılıç, Muhammet Burak

2016-01-01

In many physical systems, reliability evaluation, such as ones encountered in telecommunications, the design of integrated circuits, microwave relay stations, oil pipeline systems, vacuum systems in accelerators, computer ring networks, and spacecraft relay stations, have had applied consecutive k-out-of-n system models. These systems are characterized as logical connections among the components of the systems placed in lines or circles. In literature, a great deal of attention has been paid to the study of the reliability evaluation of consecutive k-out-of-n systems. In this paper, we propose a new method to compute the reliability of consecutive k-out-of-n:F systems, with n linearly and circularly arranged components. The proposed method provides a simple way for determining the system failure probability. Also, we write R-Project codes based on our proposed method to compute the reliability of the linear and circular systems which have a great number of components.

Metronidazole activation and isolation of Clostridium acetobutylicum electron transport genes.

PubMed Central

Santangelo, J D; Jones, D T; Woods, D R

1991-01-01

An Escherichia coli F19 recA, nitrate reductase-deficient mutant was constructed by transposon mutagenesis and shown to be resistant to metronidazole. This mutant was a most suitable host for the isolation of Clostridium acetobutylicum genes on recombinant plasmids, which activated metronidazole and rendered the E. coli F19 strain sensitive to metronidazole. Twenty-five E. coli F19 clones containing different recombinant plasmids were isolated and classified into five groups on the basis of their sensitivity to metronidazole. The clones were tested for nitrate reductase, pyruvate-ferredoxin oxidoreductase, and hydrogenase activities. DNA hybridization and restriction endonuclease mapping revealed that four of the C. acetobutylicum insert DNA fragments on recombinant plasmids were linked in an 11.1-kb chromosomal fragment. DNA sequencing and amino acid homology studies indicated that this DNA fragment contained a flavodoxin gene which encoded a protein of 160 amino acids that activated metronidazole and made the E. coli F19 mutant very sensitive to metronidazole. The flavodoxin and hydrogenase genes which are involved in electron transfer systems were linked on the 11.1-kb DNA fragment from C. acetobutylicum. Images PMID:1991710

2-Methyl-2-phenyl-1-(pyrrolidin-1-yl)propan-1-one.

PubMed

Ren, Dong-Mei

2013-05-01

In the title compound, C14H19NO, the dihedral angle between the benzene ring and the plane of the amide group is 80.6 (1)°. In the crystal, mol-ecules are connected via weak C-H⋯O hydrogen bonds, forming chains along the c-axis direction. The conformation of the five-memebred ring is an envelope, with one of the ring C atoms adjacent to the ring N atom as the flap atom.

Small-Scale Structure in Saturn's Rings

NASA Astrophysics Data System (ADS)

Rehnberg, Morgan

2017-08-01

The rings of Saturn are the largest and most complex in the Solar System. Decades of observation from ground- and space-based observatories and spacecraft missions have revealed the broad structure of the rings and the intricate interactions between the planet's moons and its rings. Stellar occultations observed by the Ultraviolet Imaging Spectrograph's High Speed Photometer onboard the Cassini spacecraft now enable the direct study of the small-scale structure that results from these interactions. In this dissertation, I present three distinct phenomena resulting from the small-scale physics of the rings. Many resonance locations with Saturn's external satellites lie within the main (A and B) rings. Two of these satellites, Janus and Epimetheus, have a unique co-orbital relationship and move radially to switch positions every 4.0 years. This motion also moves the resonance locations within the rings. As the spiral density waves created at these resonances interact, they launch an enormous solitary wave every eight years. I provide the first-ever observations of this never-predicted phenomenon and detail a possible formation mechanism. Previous studies have reported a population of kilometer-scale aggregates in Saturn's F ring, which likely form as a result of self-gravitation between ring particles in Saturn's Roche zone. I expand the known catalog of features in UVIS occultations and provide the first estimates of their density derived from comparisons with the A ring. These features are orders of magnitude less dense than previously believed, a fact which reconciles them with detections made by other means. Theory and indirect observations indicate that the smallest regular structures in the rings are wavelike aggregates called self-gravity wakes. Using the highest-resolution occulta- tions, I provide the first-ever direct detection of these features by identifying the gaps that represent the minima of the wakes. I demonstrate that the distribution of these gaps is con- sistent with the broad brightness asymmetries previously observed in the rings. Furthermore, the presence of spiral density waves affects the formation of self-gravity waves.

The adaptor protein p62 is involved in RANKL-induced autophagy and osteoclastogenesis.

PubMed

Li, Rui-Fang; Chen, Gang; Ren, Jian-Gang; Zhang, Wei; Wu, Zhong-Xing; Liu, Bing; Zhao, Yi; Zhao, Yi-Fang

2014-12-01

Previous studies have implicated autophagy in osteoclast differentiation. The aim of this study was to investigate the potential role of p62, a characterized adaptor protein for autophagy, in RANKL-induced osteoclastogenesis. Real-time quantitative PCR and western blot analyses were used to evaluate the expression levels of autophagy-related markers during RANKL-induced osteoclastogenesis in mouse macrophage-like RAW264.7 cells. Meanwhile, the potential relationship between p62/LC3 localization and F-actin ring formation was tested using double-labeling immunofluorescence. Then, the expression of p62 in RAW264.7 cells was knocked down using small-interfering RNA (siRNA), followed by detecting its influence on RANKL-induced autophagy activation, osteoclast differentiation, and F-actin ring formation. The data showed that several key autophagy-related markers including p62 were significantly altered during RANKL-induced osteoclast differentiation. In addition, the expression and localization of p62 showed negative correlation with LC3 accumulation and F-actin ring formation, as demonstrated by western blot and immunofluorescence analyses, respectively. Importantly, the knockdown of p62 obviously attenuated RANKL-induced expression of autophagy- and osteoclastogenesis-related genes, formation of TRAP-positive multinuclear cells, accumulation of LC3, as well as formation of F-actin ring. Our study indicates that p62 may play essential roles in RANKL-induced autophagy and osteoclastogenesis, which may help to develop a novel therapeutic strategy against osteoclastogenesis-related diseases. © The Author(s) 2014.

Stormtime coupling of the ring current, plasmasphere, and topside ionosphere: Electromagnetic and plasma disturbances

NASA Astrophysics Data System (ADS)

Mishin, E. V.; Burke, W. J.

2005-07-01

We compare plasma and field disturbances observed in the ring current/plasmasphere overlap region and in the conjugate ionosphere during the magnetic storm of 5 June 1991. Data come from the Combined Release and Radiation Effects Satellite (CRRES) flying in a geostationary transfer orbit and three satellites of the Defense Meteorological Satellite Program (DMSP) series in Sun-synchronous polar orbits. In the region between ring current nose structures and the electron plasma sheet, CRRES detected wave-like features in local electric and magnetic fields, embedded in structured cold plasmas. Mapped to the ionosphere, these fields should reflect structuring within subauroral plasma streams (SAPS). Indeed, during the period of interest, DMSP F8, F9, and F10 satellites observed highly structured SAPS in the evening ionosphere at topside altitudes. They were collocated with precipitating ring current ions, enhanced fluxes of suprathermal electrons and ions, elevated electron temperatures, and irregular plasma density troughs. Overall, these events are similar to electromagnetic structures observed by DMSP satellites within SAPS during recent geomagnetic storms (Mishin et al., 2003, 2004). Their features can be explained in terms of Alfvén and fast magnetosonic perturbations. We developed a scenario for the formation of elevated electron temperatures at the equatorward side of the SAPS. It includes a lower-hybrid drift instability driven by diamagnetic currents, consistent with strong lower- and upper-hybrid plasma wave activity and intense fluxes of the low-energy electrons and ions near the ring current's inner edge.

A Disk Origin for the Monoceros Ring and A13 Stellar Overdensities

NASA Astrophysics Data System (ADS)

Sheffield, Allyson A.; Price-Whelan, Adrian M.; Tzanidakis, Anastasios; Johnston, Kathryn V.; Laporte, Chervin F. P.; Sesar, Branimir

2018-02-01

The Monoceros Ring (also known as the Galactic Anticenter Stellar Structure) and A13 are stellar overdensities at estimated heliocentric distances of d ∼ 11 kpc and 15 kpc observed at low Galactic latitudes toward the anticenter of our Galaxy. While these overdensities were initially thought to be remnants of a tidally disrupted satellite galaxy, an alternate scenario is that they are composed of stars from the Milky Way (MW) disk kicked out to their current location due to interactions between a satellite galaxy and the disk. To test this scenario, we study the stellar populations of the Monoceros Ring and A13 by measuring the number of RR Lyrae and M giant stars associated with these overdensities. We obtain low-resolution spectroscopy for RR Lyrae stars in the two structures and measure radial velocities to compare with previously measured velocities for M giant stars in the regions of the Monoceros Ring and A13, to assess the fraction of RR Lyrae to M giant stars (f RR:MG) in A13 and Mon/GASS. We perform velocity modeling on 153 RR Lyrae stars (116 in the Monoceros Ring and 37 in A13) and find that both structures have very low f RR:MG. The results support a scenario in which stars in A13 and Mon/GASS formed in the MW disk. We discuss a possible association between Mon/GASS, A13, and the Triangulum-Andromeda overdensity based on their similar velocity distributions and f RR:MG.

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

Mcwilliams, A. J.; Daugherty, W. L.; Skidmore, T. E.

The 9975 Type B shipping package is used within the DOE complex for shipping special nuclear materials. This package is re-certified annually in accordance with Safety Analysis Report for Packaging (SARP) requirements. The package is also used at the Savannah River Site as part of the long-term storage configuration of special nuclear materials. As such, the packages do not undergo annual recertification during storage, with uncertainty as to how long some of the package components will meet their functional requirements in the storage environment. The packages are currently approved for up to 15 years storage, and work continues to providemore » a technical basis to extend that period. This report describes efforts by the Savannah River National Laboratory (SRNL) to extend the service life estimate of Viton® GLT and GLT-S fluoroelastomer O-rings used in the 9975 shipping package. O-rings of both GLT and GLT-S compositions are undergoing accelerated aging at elevated temperature, and are periodically tested for compression stress relaxation (CSR) behavior. The CSR behavior of O-rings was evaluated at temperatures from 175 to 400 °F. These collective data were used to develop predictive models for extrapolation of CSR behavior to relevant service temperatures (< 156 °F). The predictive model developed from the CSR data conservatively indicates a service life of approximately 37 years for Viton GLT O-rings at the maximum effective service temperature of 156 °F. The estimated service life for Viton GLT-S O-rings is significantly longer.« less

Dynamic analysis of a fibre-optic ring resonator excited by a sinewave-modulated laser diode

NASA Astrophysics Data System (ADS)

Pandian, G. Soundra; Seraji, Faramarz

1990-10-01

The present theoretical dynamic analysis of a fiber-optic ring resonator upon excitation by a sinusoidally-modulated laser diode (LD) yields results for such resonator conditions as modulating frequency, amplitude-modulation index, coupler power-coupling coefficient, loop-delay time (tau), and the phase angle between the LD's AM and FM responses. It is found that when the modulation frequency f(m) exceeds a threshold value such that f(m)tau exceeds 0.0002, the output response diverges from steady state and engages in an oscillatory behavior characterized by overshoots. When f(m)tau exceeds 1.0, the output approximates the intensity modulation of the LD.

Autoubiquitination of feline E3 ubiquitin ligase BCA2.

PubMed

Wang, Weiran; Qu, Meng; Wang, Jiawen; Zhang, Xin; Zhang, Haihong; Wu, Jiaxin; Yu, Bin; Wu, Hui; Kong, Wei; Yu, Xianghui

2018-01-05

BCA2/RNF115/Rabring7 is a RING type E3 ubiquitin ligase that is overexpressed in human breast tumors and is important for regulating breast cancer cell migration. In the present investigation, feline BCA2 (fBCA2) was identified and characterized. Compared with its human counterpart, the fBCA2 cDNA was confirmed to be 918 base pairs in length showing 92.6% consensus and identity positions, encoding a protein of 305 amino acids with 96.7% consensus and 93.1% identity positions. The fBCA2 protein contains a RING domain at the C-terminus, which was found to be essential for its autoubiquitination. Copyright © 2017. Published by Elsevier B.V.

CIRS High-Resolution Thermal Scans and the Structure of Saturn's B Ring

NASA Astrophysics Data System (ADS)

Brooks, S. M.; Spilker, L. J.; Showalter, M.; Pilorz, S.; Edgington, S. G.

2017-12-01

The flyby of Titan on November 29, 2016, sent the Cassini spacecraft on a trajectory that would take it within 10,000 kilometers of Saturn's F ring multiple times before a subsequent Titan encounter on April 22, 2017, would send it on ballistic trajectory carrying it between Saturn's cloud tops and the planet's D ring for several flybys. This geometry has proven beneficial for high-resolution studies of the rings, not just because of Cassini's proximity to the rings, but also because of the spacecraft's high elevation angle above the rings, which reduces the foreshortening that tends to degrade resolution in the ring plane. We will report on several observations of Saturn's main rings at the high spatial resolutions enabled by the end-of-mission geometry, particulary the B ring, with the Composite Infrared Spectrometer onboard Cassini during the F-ring and proximal orbits. CIRS' three infrared detectors cover a combined spectral range of 10 to 1400 cm-1 (1 mm down to 7 microns). We focus on data from Focal Plane 1, which covers the 10 to 600 cm-1 range (1 mm to 16 microns). The apodized spectral resolution of the instrument can be varied from 15 cm-1 to 0.5 cm-1 (Flasar et al. 2004). FP1's wavelength range makes it well-suited to sensing thermal emission from objects at temperatures typical of Saturn's rings. Correlating ring optical depth with temperatures retrieved from scans of the face of the rings exposed to direct solar illumination (the lit face) and the opposite (unlit) face suggests differences in ring structure or particle transport between the lit and unlit sides of the rings in different regions of the B ring. Lit side temperatures in the core of the B ring range between 82 and 87 K; temperatures on the unlit side of the core vary from 66 K up to 74 K. Ferrari and Reffet (2013) and Pilorz et al. (2015) published thorough analyses of the thermal throughput across this optically thick ring. We will discuss these recent CIRS rings observations and their implications in the context of such work. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2017 California Institute of Technology. Government sponsorship acknowledged.

Physical properties of YBa 2Cu 3O 7- δ thin films using microstrip ring resonators technique

NASA Astrophysics Data System (ADS)

Lai, L. S.; Zeng, H. K.; Juang, J. Y.; Wu, K. H.; Uen, T. M.; Lin, J. Y.; Gou, Y. S.

2006-09-01

Microstrip ring resonators with quality factor ( Q) over 10 4 at temperature 5 K, were fabricated using the double-side YBa 2Cu 3O 7- δ (YBCO) epitaxial films deposited on LaAlO 3 (LAO) substrates. By placing a narrow gap in the ring resonator, we observed that the original fundamental resonating mode (resonance frequency f = 3.61 GHz) splits into a dual-mode with different resonating frequencies ( f = 1.80 GHz and f = 5.33 GHz). These two kinds of the resonator allow us to determine the temperature and frequency dependences of the magnetic penetration depth λ( T, f) and the surface loss. Several salient features of the above findings related to the nature of low-lying excitations for high- Tc superconductivity as a function of oxygen content will be elucidated. In particular, the current models, suggested by Wen and Lee, will be examined in a quantitative manner. It allows us to give a justification of quasiparticle as Fermi-liquid in the superconducting state. In addition, an equivalent inductance circuit model is suggested to account for the occurrence of the dual-mode resonance.

Measuring (19)F shift anisotropies and (1)H-(19)F dipolar interactions with ultrafast MAS NMR.

PubMed

Martini, Francesca; Miah, Habeeba K; Iuga, Dinu; Geppi, Marco; Titman, Jeremy J

2015-10-01

A new (19)F anisotropic-isotropic shift correlation experiment is described that operates with ultrafast MAS, resulting in good resolution of isotropic (19)F shifts in the detection dimension. The new experiment makes use of a recoupling sequence designed using symmetry principles that reintroduces the (19)F chemical shift anisotropy in the indirect dimension. The situations in which the new experiment is appropriate are discussed, and the (19)F shift anisotropy parameters in poly(difluoroethylene) (PVDF) are measured. In addition, similar recoupling sequences are shown to be effective for measuring (1)H-(19)F distances via the heteronuclear dipolar interaction. This is demonstrated by application to a recently synthesized zirconium phosphonate material that contains one-dimensional chains linked by H-F hydrogen bonds. Copyright © 2015 Elsevier Inc. All rights reserved.

1-(4,4''-Difluoro-5'-meth-oxy-1,1':3',1''-terphenyl-4'-yl)ethanone.

PubMed

Fun, Hoong-Kun; Hemamalini, Madhukar; Samshuddin, S; Narayana, B; Sarojini, B K

2012-01-01

In the title compound, C(21)H(16)F(2)O(2), the central benzene ring is inclined at dihedral angles of 30.91 (8) and 46.88 (7)° to the two terminal fluoro-substituted rings. The dihedral angle between the two terminal fluoro-subsituted rings is 68.34 (8)°. An intra-molecular C-H⋯O hydrogen bond generates an S(6) ring motif. The crystal structure is stabilized by weak C-H⋯π inter-actions.

Compositional mapping of Saturn's E-ring during Cassini's flyby of Rhea

NASA Astrophysics Data System (ADS)

Khawaja, Nozair; Postberg, Frank; Srama, Ralf; Moragas-Klostermeyer, Georg; Kempf, Sascha

2015-04-01

The Cassini spacecraft was launched in 2004 towards the Saturnian system to address major scientific questions about the planet, its magnetosphere, rings and icy moons. We have performed compositional mapping of Saturn's E-ring during the Cassini's flyby (R4) of Rhea, the second largest moon of Saturn, on 9th March 2013. The icy or rocky dust particles from the surface of moons without atmosphere are ejected from their surfaces by meteoroid bombardment. The ejected particles from the moon's surface can be detected during a spacecraft flyby. In our campaign we try to identify the footprints of Rhea's surface in the composition of E ring using Cosmic Dust Analyzer (CDA) during the closest approach of Cassini's Rhea flyby. The flyby speed was 9.3km/s and the closest approach was at 997km from Rhea's surface. The Cosmic Dust Analyzer (CDA), onboard Cassini spacecraft, characterizes the micron and sub-micron dust particles at Saturn [1]. One of the tasks of CDA is to determine the chemical composition of icy and mineral dust particles at Saturn. A Time of Flight (TOF) mass spectrometer within the CDA generates mass spectra of positive ions (cations) of impinging dust particles onto the rhodium (Rh) target plate. We sampled dust grains during the entire flyby and divided the flyby into three intervals: (A) ~ -32 minutes before entering Rhea's hill sphere (B) ~ ±15 minutes from the closest approach within Rhea's hill sphere and (C) ~ +28 minutes after leaving Rhea's hill sphere. A Boxcar Analysis (BCA) is performed for compositional mapping of E-ring along the spacecraft trajectory [4]. Most of the TOF mass spectra are identified as one of the three compositional types: (i) almost pure water (ii) organic rich and (iii) salt rich [2][3]. Although we could not identify compositional information from Rhea, we have a compositional profile of the E ring. The CDA will carryout very similar measurements during Dione flyby in 2015. References [1] Srama, R. et.al.: The Cassini Cosmic Dust Analyzer, SSR, Vol. 114, 465 -- 518, 2004. [2] Postberg, F. et.al.: The E-ring in the vicinity of Enceladus II. Probing the moon's interior -- The composition of E-ring particles, Icarus, Vol. 193, 438 -- 454, 2008. [3] Postberg, F. et.al.: Sodium salts in E-ring ice grains from an ocean below the surface of Enceladus, Nature, Vol. 459, 1098 - 1101, 2009. [4] Khawaja, N. et.al.: Compositional differentiation of Enceladus' plume, EPSC, Vol. 9, 2014.

Density Waves in Saturn's Rings from Cassini Radio Occultations

NASA Astrophysics Data System (ADS)

French, R. G.; Rappaport, N. J.; Marouf, E. A.; McGhee, C. A.

2005-12-01

The Cassini Radio Science Team conducted a set of optimized diametric occultations by Saturn and its rings from May to September 2005, providing 11 separate probes of Saturn's ionosphere and atmosphere, and 12 optical depth profiles of the complete ring system. Each event was observed by the stations of the Deep Space Net (DSN) at three radio frequencies (S, X, Ka bands, with corresponding wavelengths of ? = 13, 3.6, and 0.9 cm). Very accurate pointing by the spacecraft and ground antennas resulted in stable baseline signal levels, and the relatively large ring opening angle (B=19-25°) permitted us to probe even quite dense ring regions with excellent SNR. The RSS occultation technique enables us to recover very fine detailed radial structure by correcting for diffraction effects. Multiple occultation chords, covering a variety of ring longitudes and ring opening angles, reveal the structure of the rings in remarkable detail, including density and bending waves, satellite wakes, and subtle variations at the 100-m radius scale. Janus and Epimetheus are responsible for a particularly rich set of density waves, and their coorbital interactions result in a complex interplay of time-variable ring structure over the 8-year libration period of the two satellites. We compare the first-order 2:1, 4:3, 5:4, and 6:5 coorbital density waves from multiple occultation chords to linear density wave models based on a dynamical model of the orbital exchange between the moons. From the observed dispersion relation of the wave crests, we infer the surface mass density and eccentricity gradient of particle streamlines, and match the detailed shapes of the wave crests using a non-linear analysis. Second-order coorbital features are also evident, and there are even hints of third-order density waves in the high SNR radio occultation data.

Certified Reference Material for Use in 1H, 31P, and 19F Quantitative NMR, Ensuring Traceability to the International System of Units.

PubMed

Rigger, Romana; Rück, Alexander; Hellriegel, Christine; Sauermoser, Robert; Morf, Fabienne; Breitruck, KathrinBreitruck; Obkircher, Markus

2017-09-01

In recent years, quantitative NMR (qNMR) spectroscopy has become one of the most important tools for content determination of organic substances and quantitative evaluation of impurities. Using Certified Reference Materials (CRMs) as internal or external standards, the extensively used qNMR method can be applied for purity determination, including unbroken traceability to the International System of Units (SI). The implementation of qNMR toward new application fields, e.g., metabolomics, environmental analysis, and physiological pathway studies, brings along more complex molecules and systems, thus making use of 1H qNMR challenging. A smart workaround is possible by the use of other NMR active nuclei, namely 31P and 19F. This article presents the development of three classes of qNMR CRMs based on different NMR active nuclei (1H, 31P, and 19F), and the corresponding approaches to establish traceability to the SI through primary CRMs from the National Institute of Standards and Technology and the National Metrology Institute of Japan. These TraceCERT® qNMR CRMs are produced under ISO/IEC 17025 and ISO Guide 34 using high-performance qNMR.

Characterization of solid polymer dispersions of active pharmaceutical ingredients by 19F MAS NMR and factor analysis

NASA Astrophysics Data System (ADS)

Urbanova, Martina; Brus, Jiri; Sedenkova, Ivana; Policianova, Olivia; Kobera, Libor

In this contribution the ability of 19F MAS NMR spectroscopy to probe structural variability of poorly water-soluble drugs formulated as solid dispersions in polymer matrices is discussed. The application potentiality of the proposed approach is demonstrated on a moderately sized active pharmaceutical ingredient (API, Atorvastatin) exhibiting extensive polymorphism. In this respect, a range of model systems with the API incorporated in the matrix of polvinylpyrrolidone (PVP) was prepared. The extent of mixing of both components was determined by T1(1H) and T1ρ(1H) relaxation experiments, and it was found that the API forms nanosized domains. Subsequently it was found out that the polymer matrix induces two kinds of changes in 19F MAS NMR spectra. At first, this is a high-frequency shift reaching 2-3 ppm which is independent on molecular structure of the API and which results from the long-range polarization of the electron cloud around 19F nucleus induced by electrostatic fields of the polymer matrix. At second, this is broadening of the signals and formation of shoulders reflecting changes in molecular arrangement of the API. To avoid misleading in the interpretation of the recorded 19F MAS NMR spectra, because both the contributions act simultaneously, we applied chemometric approach based on multivariate analysis. It is demonstrated that factor analysis of the recorded spectra can separate both these spectral contributions, and the subtle structural differences in the molecular arrangement of the API in the nanosized domains can be traced. In this way 19F MAS NMR spectra of both pure APIs and APIs in solid dispersions can be directly compared. The proposed strategy thus provides a powerful tool for the analysis of new formulations of fluorinated pharmaceutical substances in polymer matrices.

High-resolution imaging of Saturn's main rings during the Cassini Ring-Grazing Orbits and Grand Finale

NASA Astrophysics Data System (ADS)

Tiscareno, M. S.

2017-12-01

Cassini is ending its spectacular 13-year mission at Saturn with a two-part farewell, during which it has obtained the sharpest and highest-fidelity images ever taken of Saturn's rings. From December 2016 to April 2017, the spacecraft executed 20 near-polar orbits that passed just outside the outer edge of the main rings; these "Ring-Grazing Orbits" provided the mission's best viewing of the A and F rings and the outer B ring. From April to September 2017, the spacecraft is executing 22 near-polar orbits that pass between the innermost D ring and the planet's clouds; this "Grand Finale" provides the mission's best viewing of the C and D rings and the inner B ring. 1) Clumpy BeltsClumpy structure called "straw" was previously observed in parts of the main rings [Porco et al. 2005, Science]. New images show this structure with greater clarity. More surprisingly, new images reveal strong radial variations in the degree and character of clumpiness, which are probably an index for particle properties and interactions. Belts with different clumpiness characteristics are often adjacent to each other and not easily correlated with other ring characteristics. 2) PropellersA "propeller" is a local disturbance in the ring created by an embedded moon [Tiscareno et al. 2006, Nature; 2010, ApJL]. Cassini has observed two classes of propellers: small propellers that swarm in the "Propeller Belts" of the mid-A ring, and "Giant Propellers" whose individual orbits can be tracked in the outer A ring. Both are shown in unprecedented detail in new images. Targeted flybys of Giant Propellers were executed on both the lit and unlit sides of the ring (see figure), yielding enhanced ability to convert brightness to optical depth and surface density. 3) Impact Ejecta CloudsBeing a large and delicate system, Saturn's rings function as a detector of their planetary environment. Cassini images of impact ejecta clouds in the rings previously constrained the population of decimeter-to-meter-sized meteoroids in Saturn's vicinity [Tiscareno et al. 2013, Science]. Many more IECs are detected in new images, with color data that may constrain the particle-size distribution of the ejecta, and thus the fracture properties of ring material.

Electron shakeoff following the β+ decay of +19Ne and +35Ar trapped ions

NASA Astrophysics Data System (ADS)

Fabian, X.; Fléchard, X.; Pons, B.; Liénard, E.; Ban, G.; Breitenfeldt, M.; Couratin, C.; Delahaye, P.; Durand, D.; Finlay, P.; Guillon, B.; Lemière, Y.; Mauger, F.; Méry, A.; Naviliat-Cuncic, O.; Porobic, T.; Quéméner, G.; Severijns, N.; Thomas, J.-C.

2018-02-01

The electron shakeoff of 19F and 35Cl atoms resulting from the β+ decay of +19Ne and +35Ar ions has been investigated using a Paul trap coupled to a time of flight recoil-ion spectrometer. The charge-state distributions of the recoiling daughter nuclei were compared to theoretical calculations based on the sudden approximation and accounting for subsequent Auger processes. The excellent agreement obtained for 35Cl is not reproduced in 19F. The shortcoming is attributed to the inaccuracy of the independent particle model employed to calculate the primary shakeoff probabilities in systems with rather low atomic numbers. This calls for more elaborate calculations, including explicitly the electron-electron correlations.

Torque generation mechanism of ATP synthase

NASA Astrophysics Data System (ADS)

Miller, John; Maric, Sladjana; Scoppa, M.; Cheung, M.

2010-03-01

ATP synthase is a rotary motor that produces adenosine triphosphate (ATP), the chemical currency of life. Our proposed electric field driven torque (EFT) model of FoF1-ATP synthase describes how torque, which scales with the number of c-ring proton binding sites, is generated by the proton motive force (pmf) across the mitochondrial inner membrane. When Fo is coupled to F1, the model predicts a critical pmf to drive ATP production. In order to fully understand how the electric field resulting from the pmf drives the c-ring to rotate, it is important to examine the charge distributions in the protonated c-ring and a-subunit containing the proton channels. Our calculations use a self-consistent field approach based on a refinement of reported structural data. The results reveal changes in pKa for key residues on the a-subunit and c-ring, as well as titration curves and protonation state energy diagrams. Health implications will be briefly discussed.

Crystal structure of 4-fluoro-N-[2-(4-fluoro-benzo-yl)hydra-zine-1-carbono-thio-yl]benzamide.

PubMed

Firdausiah, Syadza; Salleh Huddin, Ameera Aqeela; Hasbullah, Siti Aishah; Yamin, Bohari M; Yusoff, Siti Fairus M

2014-09-01

In the title compound, C15H11F2N3O2S, the dihedral angle between the fluoro-benzene rings is 88.43 (10)° and that between the central semithiocarbazide grouping is 47.00 (11)°. The dihedral angle between the amide group and attached fluoro-benzene ring is 50.52 (11)°; the equivalent angle between the carbonyl-thio-amide group and its attached ring is 12.98 (10)°. The major twists in the mol-ecule occur about the C-N-N-C bonds [torsion angle = -138.7 (2)°] and the Car-Car-C-N (ar = aromatic) bonds [-132.0 (2)°]. An intra-molecular N-H⋯O hydrogen bond occurs, which generates an S(6) ring. In the crystal, the mol-ecules are linked by N-H⋯O and N-H⋯S hydrogen bonds, generating (001) sheets. Weak C-H⋯O and C-H⋯F inter-actions are also observed.

Fiber-ring laser-based intracavity photoacoustic spectroscopy for trace gas sensing.

PubMed

Wang, Qiang; Wang, Zhen; Chang, Jun; Ren, Wei

2017-06-01

We demonstrated a novel trace gas sensing method based on fiber-ring laser intracavity photoacoustic spectroscopy. This spectroscopic technique is a merging of photoacoustic spectroscopy (PAS) with a fiber-ring cavity for sensitive and all-fiber gas detection. A transmission-type PAS gas cell (resonant frequency f₀=2.68  kHz) was placed inside the fiber-ring laser to fully utilize the intracavity laser power. The PAS signal was excited by modulating the laser wavelength at f₀/2 using a custom-made fiber Bragg grating-based modulator. We used this spectroscopic technique to detect acetylene (C₂H₂) at 1531.6 nm as a proof of principle. With a low Q-factor (4.9) of the PAS cell, our sensor achieved a good linear response (R²=0.996) to C₂H₂ concentration and a minimum detection limit of 390 ppbv at 2-s response time.

Continuous wave external-cavity quantum cascade laser-based high-resolution cavity ring-down spectrometer for ultrasensitive trace gas detection.

PubMed

De, Anulekha; Banik, Gourab Dutta; Maity, Abhijit; Pal, Mithun; Pradhan, Manik

2016-05-01

A high-resolution cavity ring-down spectroscopic (CRDS) system based on a continuous wave (cw) mode-hop-free (MHF) external-cavity quantum cascade laser (EC-QCL) operating at λ∼5.2  μm has been developed for ultrasensitive detection of nitric oxide (NO). We report the performance of the high-resolution EC-QCL based cw-CRDS instrument by measuring the rotationally resolved Λ-doublet e and f components of the P(7.5) line in the fundamental band of NO at 1850.169  cm^-1 and 1850.179  cm^-1. A noise-equivalent absorption coefficient of 1.01×10^-9  cm^-1  Hz^-1/2 was achieved based on an empty cavity ring-down time of τ₀=5.6  μs and standard deviation of 0.11% with averaging of six ring-down time determinations. The CRDS sensor demonstrates the advantages of measuring parts per billion NO concentrations in N₂, as well as in human breath samples with ultrahigh sensitivity and specificity. The CRDS system could also be generalized to measure simultaneously many other trace molecular species within the broad tuning range of cw EC-QCL, as well as for studying the rotationally resolved hyperfine structures.

Space shuttle development Motor No. 9 (DM-9), volume 1

NASA Technical Reports Server (NTRS)

Garecht, Diane M.

1990-01-01

The results obtained during the December 23, 1987 static firing of the DM-9 test article are presented. The DM-9 full-scale static test article employed redesigned solid rocket motor (RSRM) field joint capture feature hardware with J-seal insulation configuration, and nozzle-to-case joint radial bolt design with bonded insulation configuration. The nozzle incorporated RSRM components, including a thicker cowl with involuted outer boot ring. The nozzle employed redundant and verifiable seals in all five joints, and room temperature vulcanization backfill in three joints. With very few exceptions, the DM-9 test article was flight configuration. The test was conducted under extreme weather conditions: temperature of 25 F and wind at 15 to 20 mph. Ballistics performance values were within specification requirements. The RSRM field joint (J-seal) insulation configuration functioned as predicted with no indication of hot gases reaching the capture feature O-rings. There was a blowhole in the polysulfide adhesive in the nozzle-to-case joint, but no evidence of hot gases past the wiper O-ring. Nozzle design changes appeared to perform nominally, with the exception of the outer boot ring, which suffered partial structural breakup late in the test. Field joint heaters maintained the controlling resistance temperature device temperature within the specified requirements during heater operation. The thrust vector control system operated properly. The redesigned water deluge system, temperature conditioning equipment, and other test support equipment performed as planned.

Frequency noise measurement of diode-pumped Nd:YAG ring lasers

NASA Technical Reports Server (NTRS)

Chen, Chien-Chung; Win, Moe Zaw

1990-01-01

The combined frequency noise spectrum of two model 120-01A nonplanar ring oscillator lasers was measured by first heterodyne detecting the IF signal and then measuring the IF frequency noise using an RF frequency discriminator. The results indicated the presence of a 1/f-squared noise component in the power-spectral density of the frequency fluctuations between 1 Hz and 1 kHz. After incorporating this 1/f-squared into the analysis of the optical phase tracking loop, the measured phase error variance closely matches the theoretical predictions.

No-carrier-added (NCA) aryl ([sup 18]F) fluorides via the nucleophilic aromatic substitution of electron rich aromatic rings

DOEpatents

Yushin Ding; Fowler, J.S.; Wolf, A.P.

1993-10-19

A method for synthesizing no-carrier-added (NCA) aryl [.sup.18 F] fluoride substituted aromatic aldehyde compositions bearing an electron donating group is described. The method of the present invention includes the step of reacting aromatic nitro aldehydes having a suitably protected hydroxyl substitutent on an electron rich ring. The reaction is The U.S. Government has rights in this invention pursuant to Contract Number DE-AC02-76CH00016, between the U.S. Department of Energy and Associated Universities Inc.

Accidental ingestion of BiTine ring and a note on inefficient ring separation forceps.

PubMed

Baghele, Om Nemichand; Baghele, Mangala Om

2011-01-01

Accidental ingestion of medium-to-large instruments is relatively uncommon during dental treatment but can be potentially dangerous. A case of BiTine ring ingestion is presented with a note on inefficient ring separation forceps. A 28-year-old male patient accidentally ingested the BiTine ring (2 cm diameter, 0.5 cm outward projections) while it was being applied to a distoproximal cavity in tooth # 19. The ring placement forceps were excessively flexible; bending of the beaks towards the ring combined with a poor no-slippage mechanism led to sudden disengagement of the ring and accelerated movement towards the pharynx. We followed the patient with bulk forming agents and radiographs. Fortunately the ring passed out without any complications. Checking equipment and methods is as important as taking precautions against any preventable medical emergency. It is the responsibility of the clinician to check, verify and then use any instrument/equipment.

Anti-austeric activity of phenolic constituents of seeds of Arctium lappa.

PubMed

Tezuka, Yasuhiro; Yamamoto, Keiichi; Awale, Suresh; Lia, Feng; Yomoda, Satoshi; Kadota, Shigetoshi

2013-04-01

From seeds of Arctium lappa L. (Asteraceae) we obtained arctigenin (1), arctiin (2), chlorogenic acid (3), 4,5-dicaffeoylquinic acid (4), 3,5-dicaffeoylquinic acid (5), 3,4-dicaffeoylquinic acid (6), matairesinol (11), isolappaol A (12), lappaol F (14), and lappaol B (15), together with 1:1 mixtures of isolappaol C (7) and lappaol C (8), arctignan E (9) and arctignan D (10), and 12 and lappaol A (13), while 3,3',4'-tri-O-demethylarctigenin (16), 3,3'-di-O-demethyl-4'-dehydroxyarctigenin (17), and 3-O-demethylarctigenin (18) were obtained by anaerobic microbiological metabolism of 1. Then, we evaluated the in vitro preferential cytotoxic activity of these pure compounds and 1:1 mixtures, together with enterodiol (19) and enterolactone (20), against human pancreatic cancer PANC-1 cells in nutrient-deprived medium (NDM). Among them, 1 and 18 showed potent activity, with PC50 values of 1.75 and 4.38 microM, respectively, while 11, 15, and 17 showed mild activity with PC50 values of 31.1, 30.9, and 38.7 microM, respectively. By comparing their structures and PC50 values, the following structural moieties could be concluded to be important for the preferential cytotoxicity of 1: 1) the 3-hydroxy-4-methoxyphenyl group at the 2-position on the gamma-butyrolactone ring, 2) the less polar substituent at the 3-position on the gamma-butyrolactone ring, and 3) the gamma-butyrolactone ring.

KSC-11415f07

NASA Image and Video Library

1997-09-21

The Cassini spacecraft awaits placement of its payload fairing at Launch Pad 40 at Cape Canaveral Air Station (CCAS) to protect Cassini during launch. Scheduled for launch in mid-October, the Cassini mission is a joint US-European four-year orbital surveillance of Saturn's atmosphere and magnetosphere, its rings, and its moons, seeks insight into the origins and evolution of the early solar system. NASA’s Jet Propulsion Laboratory is managing the Cassini project

KSC-11415f06

NASA Image and Video Library

1997-09-21

The Cassini spacecraft awaits placement of its payload fairing at Launch Pad 40 at Cape Canaveral Air Station (CCAS) to protect Cassini during launch. Scheduled for launch in mid-October, the Cassini mission is a joint US-European four-year orbital surveillance of Saturn's atmosphere and magnetosphere, its rings, and its moons, seeks insight into the origins and evolution of the early solar system. NASA’s Jet Propulsion Laboratory is managing the Cassini project

A new slip stacking RF system for a twofold power upgrade of Fermilab's Accelerator Complex

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

Madrak, Robyn

2014-05-15

Fermilab's Accelerator Complex has been recently upgraded, in order to increase the 120 GeV proton beam power on target from about 400 kW to over 700 kW for NOvA and other future intensity frontier experiments. One of the key ingredients of the upgrade is the offloading of some Main Injector synchrotron operations - beam injection and RF manipulation called ''slip stacking'' - to the 8GeV Recycler Ring, which had until recently been used only for low-intensity antiproton storage and cooling. This required construction of two new 53 MHz RF systems for the slip-stacking manipulations. The cavities operate simultaneously at Vmore » peak ≲150 kV, but at slightly different frequencies (Δf=1260 Hz). Their installation was completed in September 2013. This article describes the novel solutions used in the design of the new cavities, their tuning system, and the associated high power RF system. First results showing effective operation of the RF system, beam capture and successful slip-stacking in the Recycler Ring are presented.« less

Challenges of Cold Conditioning and Static Testing the Second Ares Demonstration Motor (DM-2)

NASA Technical Reports Server (NTRS)

Quinn, Shyla; Davis, Larry C.

2011-01-01

On August 31, 2010, a five-segment demonstration motor (DM) for the Ares program was successfully tested. A series of demonstration motors (DMs) will be tested in different conditioned environments to confirm they meet their design specifications. The second demonstration motor (DM-2) was the first cold motor. The motor needed to be subjected to sub-freezing temperatures for two months so that its internal propellant mean bulk temperature (PMBT) was approximately 40 F. Several challenges had to be overcome to make this a successful test. One challenge was to condition four field joints to get the O-rings approximately 32 F. This would be done by applying conditioning shrouds to externally cool each field joint after the test bay was pulled off. The purpose of this conditioning was to validate the new O-ring design and allow joint heaters to be eliminated. Another challenge was maintaining temperature requirements for components in the nozzle vectoring system. A separate heating system was used to warm these components during cold conditioning. There were 53 test objectives that required 764 channels of data to be recorded; 460 were specific to DM-2. This instrumentation had to be installed prior to conditioning, which meant the baseline process and timeline had to be modified to meet this time critical schedule.

An Occultation by Saturn's Rings on 1991 October 2-3 October 2-3 Observed with the Hubble Space Telescope

NASA Technical Reports Server (NTRS)

Elliot, J. L.; Bosh, A. S.; Cooke, M. L.; Bless, R. C.; Nelson, M. J.; Percival, J. W.; Taylor, M. J.; Dolan, J. F.; Robinson, E. L.; Van Citters, G. W.

1993-01-01

An occultation of the star GSC 6323-01396 (V = 11.9) by Saturn's rings was observed with the High-Speed Photometer on the Hubble Space Telescope (HST) on 1991 October 2-3. This occultation occurred when Saturn was near a stationary point, so the apparent motion of Saturn relative to the star was dominated by the HST orbital motion (8 km/s). Data were recorded simultaneously at effective wavelengths of 3200 and 7500 A, with an integration time of 0.15 s. Fifteen segments of occultation data, totaling 6.8 h, were recorded in 13 successive orbits during the 20.0 h interval from UTC 1991 October 2, 19:35 until UTC 1991 October 3, 15:35. Occultations by 43 different features throughout the classical rings were unambiguously identified in the light curve, with a second occultation by 24 of them occurring due to spacecraft orbital parallax during this extremely slow event. Occultation times for features currently presumed circular were measured and employed in a geometrical model for the rings. This model, relating the observed occultation times to feature radii and longitudes, is presented here and is used in a least-squares fit for the pole direction and radius scale of Saturn's ring system.

Arcs and Clumps in the Uranian Lambda Ring

NASA Technical Reports Server (NTRS)

Showalter, Mark R.

1995-01-01

Careful reprocessing of the Voyager images reveals that the Uranian lambda ring has marked longitudinal variations in brightness comparable in magnitude to those in Saturn's F ring and Neptune's Adams ring. The ring's variations show a dominant five-cycle (72-degree) periodicity, although additional structure down to scales of about 0.5 degree is also present. The ring's shape is defined by a small overall eccentricity plus a six-cycle (60-degree) sinusoidal variation of radial amplitude around 4 kilometers. Both of these properties can be explained by the resonant perturbations of a moon at a semimajor axis of 56,479 kilometers, but no known moon orbits at this location. Unfortunately, the mass required suggests that such a body should have been imaged by Voyager.

Design of a metasurface-based dual-band Terahertz perfect absorber with very high Q-factors for sensing applications

NASA Astrophysics Data System (ADS)

Janneh, M.; De Marcellis, A.; Palange, E.; Tenggara, A. T.; Byun, D.

2018-06-01

We report on a novel very high Q-factor dual-band Terahertz perfect absorber composed of a metasurface located on top of a flexible polyimide spacer deposited on a silver ground layer. The metasurface is a 2D-array of plasmonic nanoantennas with the shape of two concentric square rings and a cylinder positioned at their centre. By performing numerical simulations, we studied the polarisation insensitive electromagnetic response of the absorber for incident angles varying from 0° up to ±30°. The two resonant modes centred at f1 = 1.80 THz and f2 = 2.26 THz have Q-factors Q(f1) = 120 and Q(f2) = 94 and absorption coefficients A(f1) = 99 . 8 % and A(f2) = 99 . 6%. Moreover, we investigated how the resonant mode frequencies change with the refractive index and thickness of transparent analytes adsorbed on the metasurface. In terms of the Refractive Index Units (RIU), we obtained sensitivities equal to 187.5 GHz/RIU and 360 GHz/RIU for the f1 and f2 resonance frequencies, respectively, and figure of merits up to FOM = 19 . 1 and FOM∗ = 431. These results make the dual-band absorber to be employed as a sensing device able to detect the presence and/or the physical/chemical modifications of the adsorbed analytes. Moreover, we investigated the dependence of the sensitivity as a function of slight modifications of the metasurface nanoantenna shape, demonstrating that a more homogeneous distribution of the electric field intensity on the metasurface improves the sensitivity of the absorber without affecting the Q-factors.

Fluorine (19F) MRS and MRI in biomedicine

PubMed Central

Ruiz-Cabello, Jesús; Barnett, Brad P.; Bottomley, Paul A.; Bulte, Jeff W.M.

2011-01-01

Shortly after the introduction of 1H MRI, fluorinated molecules were tested as MR-detectable tracers or contrast agents. Many fluorinated compounds, which are nontoxic and chemically inert, are now being used in a broad range of biomedical applications, including anesthetics, chemotherapeutic agents, and molecules with high oxygen solubility for respiration and blood substitution. These compounds can be monitored by fluorine (19F) MRI and/or MRS, providing a noninvasive means to interrogate associated functions in biological systems. As a result of the lack of endogenous fluorine in living organisms, 19F MRI of ‘hotspots’ of targeted fluorinated contrast agents has recently opened up new research avenues in molecular and cellular imaging. This includes the specific targeting and imaging of cellular surface epitopes, as well as MRI cell tracking of endogenous macrophages, injected immune cells and stem cell transplants. PMID:20842758

NASA Tech Briefs, November 2009

NASA Technical Reports Server (NTRS)

2009-01-01

Topics covered include: Cryogenic Chamber for Servo-Hydraulic Materials Testing; Apparatus Measures Thermal Conductance Through a Thin Sample from Cryogenic to Room Temperature; Rover Attitude and Pointing System Simulation Testbed; Desktop Application Program to Simulate Cargo-Air-Drop Tests; Multimodal Friction Ignition Tester; Small-Bolt Torque-Tension Tester; Integrated Spacesuit Audio System Enhances Speech Quality and Reduces Noise; Hardware Implementation of a Bilateral Subtraction Filter; Simple Optoelectronic Feedback in Microwave Oscillators; Small X-Band Oscillator Antennas; Free-Space Optical Interconnect Employing VCSEL Diodes; Discrete Fourier Transform Analysis in a Complex Vector Space; Miniature Scroll Pumps Fabricated by LIGA; Self-Assembling, Flexible, Pre-Ceramic Composite Preforms; Flight-speed Integral Image Analysis Toolkit; Work Coordination Engine; Multi-Mission Automated Task Invocation Subsystem; Autonomously Calibrating a Quadrupole Mass Spectrometer; Determining Spacecraft Reaction Wheel Friction Parameters; Composite Silica Aerogels Opacified with Titania; Multiplexed Colorimetric Solid-Phase Extraction; Detecting Airborne Mercury by Use of Polymer/Carbon Films; Lattice-Matched Semiconductor Layers on Single Crystalline Sapphire Substrate; Pressure-Energized Seal Rings to Better Withstand Flows; Rollerjaw Rock Crusher; Microwave Sterilization and Depyrogenation System; Quantifying Therapeutic and Diagnostic Efficacy in 2D Microvascular Images; NiF2/NaF:CaF2/Ca Solid-State High-Temperature Battery Cells; Critical Coupling Between Optical Fibers and WGM Resonators; Microwave Temperature Profiler Mounted in a Standard Airborne Research Canister; Alternative Determination of Density of the Titan Atmosphere; Solar Rejection Filter for Large Telescopes; Automated CFD for Generation of Airfoil Performance Tables; Progressive Classification Using Support Vector Machines; Active Learning with Irrelevant Examples; A Data Matrix Method for Improving the Quantification of Element Percentages of SEM/EDX Analysis; Deployable Shroud for the International X-Ray Observatory; Improved Model of a Mercury Ring Damper; Optoelectronic pH Meter: Further Details; X-38 Advanced Sublimator; and Solar Simulator Represents the Mars Surface Solar Environment.

Methods and applications of positron-based medical imaging

NASA Astrophysics Data System (ADS)

Herzog, H.

2007-02-01

Positron emission tomography (PET) is a diagnostic imaging method to examine metabolic functions and their disorders. Dedicated ring systems of scintillation detectors measure the 511 keV γ-radiation produced in the course of the positron emission from radiolabelled metabolically active molecules. A great number of radiopharmaceuticals labelled with 11C, 13N, 15O, or 18F positron emitters have been applied both for research and clinical purposes in neurology, cardiology and oncology. The recent success of PET with rapidly increasing installations is mainly based on the use of [ 18F]fluorodeoxyglucose (FDG) in oncology where it is most useful to localize primary tumours and their metastases.

A self optimizing synthetic organic reactor system using real-time in-line NMR spectroscopy.

PubMed

Sans, Victor; Porwol, Luzian; Dragone, Vincenza; Cronin, Leroy

2015-02-01

A configurable platform for synthetic chemistry incorporating an in-line benchtop NMR that is capable of monitoring and controlling organic reactions in real-time is presented. The platform is controlled via a modular LabView software control system for the hardware, NMR, data analysis and feedback optimization. Using this platform we report the real-time advanced structural characterization of reaction mixtures, including 19 F, 13 C, DEPT, 2D NMR spectroscopy (COSY, HSQC and 19 F-COSY) for the first time. Finally, the potential of this technique is demonstrated through the optimization of a catalytic organic reaction in real-time, showing its applicability to self-optimizing systems using criteria such as stereoselectivity, multi-nuclear measurements or 2D correlations.

WWII (World War II) Era Building Demolition and Renovation Cost Estimator (ESTER) 1.0 User’s Manual

DTIC Science & Technology

1988-07-01

S.F., fiberglass, R-13 */ Idefine BLO F R19 0.91 /* S.F., fiberglass, R-19 */ Idefine B M RII 0.54 /* S.F., mineral wool , R-1l 1i /define W M RI13...0.81 /* S.F., mineral wool , R-13 */ idefine BLOMR19 1.16 /* S.F., mineral wool , R-19 */ .define BSW C R26 0.91 /* S.F., cellulose, R-26 */ Idefine BL

Measured 19F(α,n) with VANDLE for Nuclear Safeguards

NASA Astrophysics Data System (ADS)

Peters, William; Clement, R. C. C.; Smith, M. S.; Pain, S.; Febbraro, M.; Pittman, S.; Thomspon, S.; Grinder, M.; Cizewski, J. A.; Reingold, C.; Manning, B.; Burcher, S.; Bardayan, D. W.; Tan, W.-P.; Stech, E.; Smith, M. K.; Avetisyan, R.; Gyurjinyan, A.; Lowe, M.; Ilyushkin, S.; Grzywacz, R.; Madurga, M.; Paulauskas, S. V.; Taylor, S. Z.; Smith, K.

2015-10-01

One of the most promising non-destructive assay (NDA) methods to monitor UF6 canisters consists of measuring gross neutron rates induced by uranium-decay alpha particles reacting with the fluorine and emitting a neutron. This method currently lacks reliable nuclear data on the 19F(α,n) reaction cross section to determine an accurate neutron yield rate for a given sample of UF6. We have measured the cross section and coincident neutron spectrum for the alpha-decay energy range using the VANDLE system. This experiment had two parts: first at Notre Dame with a LaF3 target and and a pulsed alpha-particle beam, and second at ORNL with a windowless He-gas target and a 19F beam. The motivation for this measurement and cross section results will be presented. This work is funded in part by the DOE Office of Science, the National Nuclear Security Administration SSAA and the Office of Defense Nuclear Nonproliferation R&D, and the NSF.

Radiation exposure to nuclear medicine staffs during 18F-FDG PET/CT procedures at Ramathibodi Hospital

NASA Astrophysics Data System (ADS)

Donmoon, T.; Chamroonrat, W.; Tuntawiroon, M.

2016-03-01

The aim of this study is to estimate the whole body and finger radiation doses per study received by nuclear medicine staff involved in dispensing, administration of 18F-FDG and interacting with radioactive patients during PET/CT imaging procedures in a PET/CT facility. The whole-body doses received by radiopharmacists, technologists and nurses were measured by electronic dosimeter and the finger doses by ring dosimeter during a period of 4 months. In 70 PET/CT studies, the mean whole-body dose per study to radiopharmacist, technologist, and nurse were 1.07±0.09, 1.77±0.46, μSv, and not detectable respectively. The mean finger doses per study received by radiopharmacist, technologist, and nurse were 265.65±107.55, 4.84±1.08 and 19.22±2.59 μSv, respectively. The average time in contact with 18F-FDG was 5.88±0.03, 39.06±1.89 and 1.21±0.02 minutes per study for radiopharmacist, technologist and nurse respectively. Technologists received highest mean effective whole- body dose per study and radiopharmacist received the highest finger dose per study. When compared with the ICRP dose limit, each individual worker can work with many more 18F- FDG PET/CT studies for a whole year without exceeding the occupational dose limits. This study confirmed that low levels of radiation does are received by our medical personnel involved in 18F-FDG PET/CT procedures.

Side-chain conformation of the M2 transmembrane peptide proton channel of influenza a virus from 19F solid-state NMR.

PubMed

Luo, Wenbin; Mani, Rajeswari; Hong, Mei

2007-09-13

The M2 transmembrane peptide (M2TMP) of the influenza A virus forms a tetrameric helical bundle that acts as a proton-selective channel important in the viral life cycle. The side-chain conformation of the peptide is largely unknown and is important for elucidating the proton-conducting mechanism and the channel stability. Using a 19F spin diffusion NMR technique called CODEX, we have measured the oligomeric states and interhelical side chain-side chain 19F-19F distances at several residues using singly fluorinated M2TMP bound to DMPC bilayers. 19F CODEX data at a key residue of the proton channel, Trp41, confirm the tetrameric state of the peptide and yield a nearest-neighbor interhelical distance of approximately 11 A under both neutral and acidic pH. Since the helix orientation is precisely known from previous 15N NMR experiments and the backbone channel diameter has a narrow allowed range, this 19F distance constrains the Trp41 side-chain conformation to t90 (chi1 approximately 180 degrees , chi2 approximately 90 degrees ). This Trp41 rotamer, combined with a previously measured 15N-13C distance between His37 and Trp411, suggests that the His37 rotamer is t-160. The implication of the proposed (His37, Trp41) rotamers to the gating mechanism of the M2 proton channel is discussed. Binding of the antiviral drug amantadine to the peptide does not affect the F-F distance at Trp41. Interhelical 19F-19F distances are also measured at residues 27 and 38, each mutated to 4-19F-Phe. For V27F-M2TMP, the 19F-19F distances suggest a mixture of dimers and tetramers, whereas the L38F-M2TMP data indicate two tetramers of different sizes, suggesting side chain conformational heterogeneity at this lipid-facing residue. This work shows that 19F spin diffusion NMR is a valuable tool for determining long-range intermolecular distances that shed light on the mechanism of action and conformational heterogeneity of membrane protein oligomers.

New patterns in dust off the edge of Saturn’s main rings

NASA Astrophysics Data System (ADS)

Chancia, Robert Ormal; Hedman, Matthew M.; Ye, Shengyi; Kurth, William S.

2017-10-01

The Roche Division is a 3000-km-span of diffuse dust located at the outer edge of Saturn’s main ring system between the A and F rings. Several high-resolution images from Cassini’s orbit insertion revealed two regions with higher concentrations of dust within the Roche Division. These proposed dusty ringlets R/2004 S1 (radius=137,630 km) and R/2004 S2 (radius=138,900 km) lie coincident with the orbit of Atlas and slightly interior to the orbit of Prometheus respectively (Porco et al. 2005a Science). Using several image sequences later obtained by Cassini Hedman et al. 2009 (Icarus) found that these concentrations of dusty ring material are not simple ringlets, but are in fact organized into canted azimuthal brightness variations with a periodicity akin to a 3:4 resonance with Saturn’s rotation rate. The presumed perturbing phenomenon is Saturn’s kilometric radiation (SKR), a strong low wavelength component of the planet’s radio emissions, whose power oscillates near the planet’s rotation rate at a frequency matching the Roche Division structures. However, over the course of the Cassini mission the SKR period has varied by at least 7 minutes. As a result, the location of the resonance moved interior to the edge of the A ring and out of the Roche Division around the time of Saturn’s equinox. Subsequent observations of the Roche Division in the this time period show no evidence of the prominent structures previously observed during the first few years of the Cassini mission. Recently, the 3:4 resonant structures have reappeared in the Roche Division as one of the SKR periods has increased. Here we show that the these dusty Roche Division structures are present in sync with the varying SKR period using images sequences spanning the entire Cassini mission. We also highlight some particularly optimal observations, obtained during Cassini’s F-ring proximal and grand finale orbits, which reveal the dusty structure of the Roche Division in unprecedented detail.

Actions of a versatile fluorene-degrading bacterial isolate on polycyclic aromatic compounds.

PubMed Central

Grifoll, M; Selifonov, S A; Gatlin, C V; Chapman, P J

1995-01-01

Pseudomonas cepacia F297 grew with fluorene as a sole source of carbon and energy; its growth yield corresponded to an assimilation of about 40% of fluorene carbon. The accumulation of a ring meta-cleavage product during growth and the identification of 1-indanone in growth media and washed-cell suspensions suggest that strain F297 metabolizes fluorene by mechanisms analogous to those of naphthalene degradation. In addition to fluorene, strain F297 utilized for growth a wide variety of polycyclic aromatic compounds (PACs), including naphthalene, 2,3-dimethylnaphthalene, phenanthrene, anthracene, and dibenzothiophene. Fluorene-induced cells of the strain also transformed 2,6-dimethylnaphthalene, biphenyl, dibenzofuran, acenaphthene, and acenaphthylene. The identification of products formed from those substrates (by gas chromatography-mass spectrometry) in washed-cell suspensions indicates that P. cepacia F297 carries out the following reactions: (i) aromatic ring oxidation and cleavage, apparently using the pyruvate released for growth, (ii) methyl group oxidations, (iii) methylenic oxidations, and (iv) S oxidations of aromatic sulfur heterocycles. Strain F297 grew with a creosote-PAC mixture, producing an almost complete removal of all aromatic compounds containing 2 to 3 rings in 14 days, as demonstrated by gas chromatography analysis of the remaining PACs recovered from cultures. The identification of key chemicals confirmed that not only are certain compounds depleted but also the anticipated reaction products are found. PMID:7487007

Actions of a versatile fluorene-degrading bacterial isolate on polycyclic aromatic compounds.

PubMed

Grifoll, M; Selifonov, S A; Gatlin, C V; Chapman, P J

1995-10-01

Pseudomonas cepacia F297 grew with fluorene as a sole source of carbon and energy; its growth yield corresponded to an assimilation of about 40% of fluorene carbon. The accumulation of a ring meta-cleavage product during growth and the identification of 1-indanone in growth media and washed-cell suspensions suggest that strain F297 metabolizes fluorene by mechanisms analogous to those of naphthalene degradation. In addition to fluorene, strain F297 utilized for growth a wide variety of polycyclic aromatic compounds (PACs), including naphthalene, 2,3-dimethylnaphthalene, phenanthrene, anthracene, and dibenzothiophene. Fluorene-induced cells of the strain also transformed 2,6-dimethylnaphthalene, biphenyl, dibenzofuran, acenaphthene, and acenaphthylene. The identification of products formed from those substrates (by gas chromatography-mass spectrometry) in washed-cell suspensions indicates that P. cepacia F297 carries out the following reactions: (i) aromatic ring oxidation and cleavage, apparently using the pyruvate released for growth, (ii) methyl group oxidations, (iii) methylenic oxidations, and (iv) S oxidations of aromatic sulfur heterocycles. Strain F297 grew with a creosote-PAC mixture, producing an almost complete removal of all aromatic compounds containing 2 to 3 rings in 14 days, as demonstrated by gas chromatography analysis of the remaining PACs recovered from cultures. The identification of key chemicals confirmed that not only are certain compounds depleted but also the anticipated reaction products are found.

Cassini's Grand Finale and Recent Science Highlights

NASA Astrophysics Data System (ADS)

Spilker, Linda J.

2017-06-01

After almost 13 years in Saturn orbit, the Cassini-Huygens mission has entered its final year of data collection. Cassini will return its final bits of unique data on 15 September 2017 as it plunges into Saturn’s atmosphere, vaporizing and satisfying planetary protection requirements.Since early 2016 Cassini’s orbital inclination was slowly increased towards its final inclination. In November Cassini transitioned to a series of 20 orbits with periapses just outside Saturn's F ring that included some of the closest flybys of the tiny ring moons and excellent views of the F ring and outer A ring.Cassini's final close flyby of Titan in April 2017 propelled it across Saturn’s main rings and into its final orbits. Cassini's Grand Finale began in April 2017 and is comprised of 22 orbits at an inclination of 63 degrees. Cassini is repeatedly diving between the innermost ring and Saturn's upper atmosphere providing insights into fundamental questions unattainable during the rest of the mission. It is the first spacecraft to explore this region.These close orbits provide the highest resolution observations of both the rings and Saturn, and direct in situ sampling of the ring particles' composition, plasma, Saturn's exosphere and the innermost radiation belts. Saturn's gravitational field will be measured to unprecedented accuracy, providing information on Saturn's interior structure and mass distribution in the rings. Probing the magnetic field will give insight into the nature of the magnetic dynamo and the true rotation rate of Saturn's interior. The ion and neutral mass spectrometer will sniff the exosphere and upper atmosphere and examine water-based molecules originating from the rings. The cosmic dust analyzer will sample particle composition from different parts of the main rings.Recent science highlights and science objectives from Cassini’s final orbits will be discussed.This work was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2017 California Institute of Technology. Government sponsorship is acknowledged.

SU-F-T-08: Brachytherapy Film Dosimetry in a Water Phantom for a Ring and Tandem HDR Applicator

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

Lee, B; Grelewicz, Z; Kang, Z

2016-06-15

Purpose: The feasibility of dose measurement using new generation EBT3 film was explored in a water phantom for a ring and tandem HDR applicator for measurements tracking mucosal dose during cervical brachytherapy. Methods: An experimental fixture was assembled to position the applicator in a water phantom. Prior to measurement, calibration curves for EBT3 film in water and in solidwater were verified. EBT3 film was placed at different known locations around the applicator in the water tank. A CT scan of the phantom with applicator was performed using clinical protocol. A typical cervical cancer treatment plan was then generated by Oncentramore » brachytherapy planning system. A dose of 500 cGy was prescribed to point A (2 cm, 2 cm). Locations measured by film included the outer surface of the ring, measurement point A-m (2.2 cm, 2.2 cm), and profiles extending from point A-m parallel to the tandem. Three independent measurements were conducted. The doses recorded by film were carefully analyzed and compared with values calculated by the treatment planning system. Results: Assessment of the EBT3 films indicate that the dose at point A matches the values predicted by the planning system. Dose to the point A-m was 411.5 cGy, and the outer circumferential surface dose of the ring was between 500 and 1150 cGy. It was found that from the point A-m, the dose drops 60% within 4.5 cm on the line parallel to the tandem. The measurement doses agree with the treatment planning system. Conclusion: Use of EBT3 film is feasible for in-water measurements for brachytherapy. A carefully machined apparatus will likely improve measurement accuracy. In a typical plan, our study found that the ring surface dose can be 2.5 times larger than the point A prescription dose. EBT3 film can be used to monitor mucosal dose in brachytherapy treatments.« less

Novel and unusual triterpene from Black Cohosh. Determination of structure of 9,10-seco-9,19-cyclolanostane xyloside (cimipodocarpaside) by NMR, IR and Raman spectroscopy and DFT calculations.

PubMed

Jamróz, Marta K; Jamróz, Michał H; Dobrowolski, Jan Cz; Gliński, Jan A; Davey, Matthew H; Wawer, Iwona

2011-01-01

A new triterpene xyloside, designated cimipodocarpaside was isolated from a Black Cohosh (Actea racemosa L.) extract and its structure was elucidated by means of 1H, 13C NMR, IR and Raman spectroscopy supported by B3LYP/6-31G** calculations. The vibrational spectra were interpreted using the PED analysis of 273 fundamentals. Its structure comprises four condensed rings A-D which are 6, 7, 6, and 5-membered, respectively. An oxiirane ring is located in the side chain and a xylose moiety is attached to the A-ring. Comparison of the experimental 13C NMR data with the theoretical chemical shifts of 24S- and 24R-cimipodocarpaside isomers revealed that the isolated compound has the 24S-configuration. Combined spectroscopic and computational studies enabled the determination of the structure of cimipodocarpaside as (24S)-3β-hydroxy-24,25-oxiirane-16,23-dione-9,10-seco-9,19-cyclolanost-7(8),9(11),10(19)-trien-3-O-β-D-xylopyranoside. Triterpenes with 7-membered ring were thus far isolated from only Actea podocarpa DC. plants. This is the first report on the isolation of such a compound from Black Cohosh. Copyright © 2010 Elsevier B.V. All rights reserved.

Novel and unusual triterpene from Black Cohosh. Determination of structure of 9,10- seco-9,19-cyclolanostane xyloside (cimipodocarpaside) by NMR, IR and Raman spectroscopy and DFT calculations

NASA Astrophysics Data System (ADS)

Jamróz, Marta K.; Jamróz, Michał H.; Dobrowolski, Jan Cz.; Gliński, Jan A.; Davey, Matthew H.; Wawer, Iwona

2011-01-01

A new triterpene xyloside, designated cimipodocarpaside was isolated from a Black Cohosh ( Actea racemosa L.) extract and its structure was elucidated by means of 1H, 13C NMR, IR and Raman spectroscopy supported by B3LYP/6-31G** calculations. The vibrational spectra were interpreted using the PED analysis of 273 fundamentals. Its structure comprises four condensed rings A-D which are 6, 7, 6, and 5-membered, respectively. An oxiirane ring is located in the side chain and a xylose moiety is attached to the A-ring. Comparison of the experimental 13C NMR data with the theoretical chemical shifts of 24 S- and 24 R-cimipodocarpaside isomers revealed that the isolated compound has the 24 S-configuration. Combined spectroscopic and computational studies enabled the determination of the structure of cimipodocarpaside as (24 S)-3β-hydroxy-24,25-oxiirane-16,23-dione-9,10- seco-9,19-cyclolanost-7(8),9(11),10(19)-trien-3-O-β- D-xylopyranoside. Triterpenes with 7-membered ring were thus far isolated from only Actea podocarpa DC. plants. This is the first report on the isolation of such a compound from Black Cohosh.

Increasing carbon discrimination rates and depth of water uptake favor the growth of Mediterranean evergreen trees in the ecotone with temperate deciduous forests.

PubMed

Barbeta, Adrià; Peñuelas, Josep

2017-12-01

Tree populations at the low-altitudinal or -latitudinal limits of species' distributional ranges are predicted to retreat toward higher altitudes and latitudes to track the ongoing changes in climate. Studies have focused on the climatic sensitivity of the retreating species, whereas little is known about the potential replacements. Competition between tree species in forest ecotones will likely be strongly influenced by the ecophysiological responses to heat and drought. We used tree-ring widths and δ 13 C and δ 18 O chronologies to compare the growth rates and long-term ecophysiological responses to climate in the temperate-Mediterranean ecotone formed by the deciduous Fagus sylvatica and the evergreen Quercus ilex at the low altitudinal and southern latitudinal limit of F. sylvatica (NE Iberian Peninsula). F. sylvatica growth rates were similar to those of other southern populations and were surprisingly not higher than those of Q. ilex, which were an order of magnitude higher than those in nearby drier sites. Higher Q. ilex growth rates were associated with high temperatures, which have increased carbon discrimination rates in the last 25 years. In contrast, stomatal regulation in F. sylvatica was proportional to the increase in atmospheric CO 2 . Tree-ring δ 18 O for both species were mostly correlated with δ 18 O in the source water. In contrast to many previous studies, relative humidity was not negatively correlated with tree-ring δ 18 O but had a positive effect on Q. ilex tree-ring δ 18 O. Furthermore, tree-ring δ 18 O decreased in Q. ilex over time. The sensitivity of Q. ilex to climate likely reflects the uptake of deep water that allowed it to benefit from the effect of CO 2 fertilization, in contrast to the water-limited F. sylvatica. Consequently, Q. ilex is a strong competitor at sites currently dominated by F. sylvatica and could be favored by increasingly warmer conditions. © 2017 John Wiley & Sons Ltd.

4-[(E)-(2,4-Difluoro­phen­yl)(hydroxy­imino)meth­yl]piperidinium picrate

PubMed Central

Jasinski, Jerry P.; Butcher, Ray J.; Yathirajan, H. S.; Mallesha, L.; Mohana, K. N.

2009-01-01

The title compound, C12H15F2N2O+·C6H2N3O7 −, a picrate salt of 4-[(E)-(2,4-difluoro­phen­yl)(hydroxy­imino)meth­yl]piper­idine, crystallizes with two independent mol­ecules in a cation–anion pair in the asymmetric unit. In the cation, a methyl group is tris­ubstituted by hydroxy­imino, piperidin-4-yl and 2,4-difluoro­phenyl groups, the latter of which contains an F atom disordered over two positions in the ring [occupancy ratio 0.631 (4):0.369 (4)]. The mean plane of the hydr­oxy group is in a synclinical conformation nearly orthogonal [N—C—C—C = 72.44 (19)°] to the mean plane of the piperidine ring, which adopts a slightly distorted chair conformation. The dihedral angle between the mean plane of the 2,4-difluoro­phenyl and piperidin-4-yl groups is 60.2 (3)°. In the picrate anion, the mean planes of the two o-NO2 and single p-NO2 groups adopt twist angles of 5.7 (2), 25.3 (7) and 8.3 (6)°, respectively, with the attached planar benzene ring. The dihedral angle between the mean planes of the benzene ring in the picrate anion and those in the hydroxy­imino, piperidin-4-yl and 2,4-difluoro­phenyl groups in the cation are 84.9 (7), 78.9 (4) and 65.1 (1)°, respectively. Extensive hydrogen-bond inter­actions occur between the cation–anion pair, which help to establish the crystal packing in the unit cell. This includes dual three-center hydrogen bonds with the piperidin-4-yl group, the phenolate and o-NO2 O atoms of the picrate anion at different positions in the unit cell, which form separate N—H⋯(O,O) bifurcated inter­molecular hydrogen-bond inter­actions. Also, the hydr­oxy group forms a separate hydrogen bond with a nearby piperidin-4-yl N atom, thus providing two groups of hydrogen bonds, which form an infinite two-dimensional network along (011). PMID:21577832

Hubble Discovery Image of New Moon Orbiting Saturn

NASA Technical Reports Server (NTRS)

1995-01-01

This four-picture sequence (spanning 30 minutes) shows one of four new moons discovered by the Hubble Space Telescope, in images taken of Saturn on May 22, 1995, when Saturn's rings were tilted edge-on to Earth.

Identified as S/1995 S3, the moon appears as an elongated white spot near the center of each image. The new moon lies just outside Saturn's outermost 'F' ring and is no bigger than about 15 miles across. The brighter object to the left is the moon Epimetheus, which was discovered during the ring-plane crossing of 1966. Both moons change position from frame to frame because they are orbiting the planet.

Saturn appears as a bright white disk at far right, and the edge-on rings extend diagonally to the upper left. To the left of the vertical line, each image has been processed to remove residual light from the rings and accentuate any faint satellites orbiting near the rings. The long observing times necessary to detect the faint satellites have resulted in Saturn's bright, overexposed appearance.

Saturn ring plane crossings happen only once every 15 years, and historically have given astronomers an opportunity to discover new satellites that are normally lost in the glare of the planet's bright ring system.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

Ab initio electronic structure of the progestogen norethisterone and its 5 alpha-derivatives.

PubMed

Kubli-Garfias, Carlos; Vázquez, Ricardo; Cooney, Austin J; Larrea, Fernando

2002-11-01

The steroid 17 alpha-ethynyl-19-nor-4-androsten-17 beta-ol, 3-one (Norethisterone; NET) and its 5 alpha-dihydro (5 alpha-NET), 3 alpha- and 3 beta-tetrahydro derivatives (3 alpha,5 alpha- and 3 beta,5 alpha-NET), were comparatively studied by the ab initio quantum mechanics theory. Additionally, 5 alpha-androstan-3 beta,17 beta-diol (ADIOL) was also studied. The Hartree-Fock method and the 6-31G(*) basis set were used to obtain the lowest energy conformation, geometries, electronic structure and physicochemical properties of the steroids. The results showed bond distances and valence angles similar among all steroids, but some differences in dihedral angles in the A-B-ring system were observed. The electronic structure analysis showed that NET has both frontier orbitals that is, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) located at the C4-C5 pi-bond. In A-ring reduced derivatives, the HOMO was found at the 17 beta-OH and ethynyl groups. In the case of 5 alpha-NET, the LUMO was confined to the A-ring and its C3 carbonyl group while the two NET tetrahydro-reduced derivatives showed the LUMO at the 17 beta-OH and ethynyl groups. The energy changes of the rotational barrier of the 17 beta-OH group suggest that its movement is somewhat restricted by the 17 alpha-ethynyl group. Interestingly both groups at C17 form a single electrostatic potential with high electronic density. On the other side, the 19-nor condition increases the A-ring mobility. However, the 3 beta-OH group of 3 beta,5 alpha-NET may rotate without significant energy differences as compared to the same group in ADIOL. The electronic structure of NET and its A-ring reduced derivatives explains in some extent their interaction with androgen and progesterone receptors as well as their selectivity for the estrogen alpha-receptor.

Rapid Multiplex Assay for Serotyping Pneumococci with Monoclonal and Polyclonal Antibodies

PubMed Central

Yu, Jigui; Lin, Jisheng; Benjamin, William H.; Waites, Ken B.; Lee, Che-hung; Nahm, Moon H.

2005-01-01

We have developed and characterized a rapid semiautomated pneumococcal serotyping system incorporating a pneumococcal lysate preparation protocol and a multiplex serotyping assay. The lysate preparation incorporates a bile solubility test to confirm pneumococcal identification that also enhances assay specificity. The multiplex serotyping assay consists of 24 assays specific for 36 serotypes: serotypes 1, 2, 3, 4, 5, 6A, 6B, 7A/7F, 8, 9L/9N, 9V, 10A/10B/39/(33C), 11A/11D/11F, 12A/12B/12F, 14, 15B/(15C), 17F, 18C, 19A, 19F, 20, 22A/22F, 23F, and 33A/33F. The multiplex assay requires a flow cytometer, two sets of latex particles coated with pneumococcal polysaccharides, and serotype-specific antibodies. Fourteen newly developed monoclonal antibodies specific for common serotypes and a pool of polyclonal rabbit sera for some of the less-common serotypes are used. The two monoclonal antibodies specific for serotypes 18C and 23F recognize serotype-specific epitopes that have not been previously described. These monoclonal antibodies make the identification of the 14 common serotypes invariant. The specificity of the serotyping assay is fully characterized with pneumococci of all known (i.e., 90) serotypes. The assay is sensitive enough to use bacterial lysates diluted 20 fold. Our serotyping system can identify not only all the serotypes in pneumococcal vaccines but also most (>90%) of clinical isolates. This system should be very useful in serotyping clinical isolates for evaluating pneumococcal vaccine efficacy. PMID:15634965

Cassini's Grand Finale Overview

NASA Astrophysics Data System (ADS)

Spilker, L. J.

2017-12-01

After 13 years in orbit, the Cassini-Huygens Mission to Saturn ended in a science-rich blaze of glory. Cassini sent back its final bits of unique science data on September 15, 2017, as it plunged into Saturn's atmosphere, vaporizing and satisfying planetary protection requirements. Cassini's final phase covered roughly ten months and ended with the first time exploration of the region between the rings and planet. In late 2016 Cassini transitioned to a series of 20 Ring Grazing orbits with peripases just outside Saturn's F ring, providing close flybys of tiny ring moons, including Pan, Daphnis and Atlas, and high-resolution views of Saturn's A and F rings. A final Titan flyby in late April 2017 propelled Cassini across Saturn's main rings and into its Grand Finale orbits. Comprised of 22 orbits, Cassini repeatedly dove between Saturn's innermost rings and upper atmosphere to answer fundamental questions unattainable earlier in the mission. The last orbit turned the spacecraft into the first Saturn atmosphere probe. The Grand Finale orbits provided highest resolution observations of both the rings and Saturn, and in-situ sampling of the ring particle composition, Saturn's atmosphere, plasma, and innermost radiation belts. The gravitational field was measured to unprecedented accuracy, providing information on the interior structure of the planet, winds in the deeper atmosphere, and mass of the rings. The magnetic field provided insight into the physical nature of the magnetic dynamo and structure of the internal magnetic field. The ion and neutral mass spectrometer sampled the upper atmosphere for molecules that escape the atmosphere in addition to molecules originating from the rings. The cosmic dust analyzer directly sampled the composition from different parts of the main rings for the first time. Fields and particles instruments directly measured the plasma environment between the rings and planet. Science highlights and new mysteries collected in the Grand Finale orbits will be discussed. The research described in this paper was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Copyright 2017 California Institute of Technology. Government sponsorship is acknowledged.

Ring-opening polymerization of 19-electron [2]cobaltocenophanes: a route to high-molecular-weight, water-soluble polycobaltocenium polyelectrolytes.

PubMed

Mayer, Ulrich F J; Gilroy, Joe B; O'Hare, Dermot; Manners, Ian

2009-08-05

Water-soluble, high-molecular-weight polycobaltocenium polyelectrolytes have been prepared by ring-opening polymerization (ROP) techniques. Anionic polymerization of a strained 19-electron dicarba[2]cobaltocenophane followed by oxidation in the presence of ammonium chloride resulted in the formation of oligomers with up to nine repeat units. Thermal ROP of dicarba[2]cobaltocenophane followed by oxidation in the presence of ammonium nitrate resulted in the formation of high-molecular-weight polycobaltocenium nitrate, a redox-active cobalt-containing polyelectrolyte.

Saturn Ring-Plane Crossing, may 1995

NASA Astrophysics Data System (ADS)

Bosh, Amanda

1995-07-01

In 1995-1996, the Earth and the Sun will pass through Saturn's ring plane. The Earth will pass through 3 times (22 May 1995, 10 August 1995, 11 Feb 1996), and the Sun will pass through once (19 November 1995). All but the 11 Feb 1996 event will be visible from HST. During the crossings of the Earth through Saturn's ring plane, the rings will become very thin and dark. By monitoring the brightness of the rings as they become very thin, we will be able to determine the time of ring-plane crossing and the residual brightness of the rings at this time. The time of the ring- plane crossing will place additional constraints on the precession rate of Saturn's pole. The recent occultations by Saturn's rings have produced a measurement of this value, but it is not known very well (French et al., 1993; Bosh, 1994; Elliot et al., 1993). A measure of the brightness of the rings in their edge-on configuration, combined with photometric properties of the rings derived from early calibration observations will allow us to determine the thickness of the rings.

Feasibility Assessment of Thermal Barrier Seals for Extreme Transient Temperatures

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Dunlap, Patrick H., Jr.

1998-01-01

The assembly joints of modem solid rocket motor cases are generally sealed using conventional O-ring type seals. The 5500+ F combustion gases produced by rocket motors are kept a safe distance away from the seals by thick layers of phenolic insulation. Special compounds are used to fill insulation gaps leading up to the seals to prevent a direct flowpath to them. Design criteria require that the seals should not experience torching or charring during operation, or their sealing ability would be compromised. On limited occasions, NASA has observed charring of the primary O-rings of the Space Shuttle solid rocket nozzle assembly joints due to parasitic leakage paths opening up in the gap-fill compounds during rocket operation. NASA is investigating different approaches for preventing torching or charring of the primary O-rings. One approach is to implement a braided rope seal upstream of the primary O-ring to serve as a thermal barrier that prevents the hot gases from impinging on the O-ring seals. This paper presents flow, resiliency, and thermal resistance for several types of NASA rope seals braided out of carbon fibers. Burn tests were performed to determine the time to burn through each of the seals when exposed to the flame of an oxyacetylene torch (5500 F), representative of the 5500 F solid rocket motor combustion temperatures. Rope seals braided out of carbon fibers endured the flame for over six minutes, three times longer than solid rocket motor burn time. Room and high temperature flow tests are presented for the carbon seals for different amounts of linear compression. Room temperature compression tests were performed to assess seal resiliency and unit preloads as a function of compression. The thermal barrier seal was tested in a subscale "char" motor test in which the seal sealed an intentional defect in the gap insulation. Temperature measurements indicated that the seal blocked 2500 F combustion gases on the upstream side with very little temperature rise on the downstream side.

Evaluation of thyroid function tests of acne vulgaris patients treated with systemic isotretinoin.

PubMed

Yıldırım, Neslihan; Doğan, Sibel; Atakan, Nilgün

2017-03-01

Isotretinoin is a systemic retinoid used to treat acne and it binds receptors which are the member of steroid-thyroid hormone superfamily. Certain types of retinoids may cause abnormalities in serum thyroid function tests (sTFTs) by suppressing thyroid stimulating hormone (TSH). However, it is uncertain whether systemic isotretinoin has any effect on sTFTs. The aim of the study was to find out if there is any alteration in sTFTs of patients with acne vulgaris treated with systemic isotretinoin. A total of 51 patients (male/female: 22/29) with severe acne vulgaris treated with a total dose of 120 mg/kg isotretinoin were included into the study prospectively. Serum free T3 (fT3), free T4 (fT4) and TSH levels were measured at baseline, 3rd and 6th months of treatment. Mean serum TSH levels at baseline, 3rd and 6th months of treatment were 1.57 ± 0.67, 2.07 ± 0.88 and 2.25 ± 0.86 uIU/mL, respectively. Mean serum TSH levels increased significantly following isotretinoin therapy (p < 0.01, p = 0.007 and p < 0.01, respectively). Mean serum fT3 levels at baseline, 3rd and 6th months of treatment were 3.59 ± 0.57, 3.19 ± 0.45 and 3.09 ± 0.61 pmol/L, respectively. Mean serum fT4 levels at baseline, 3rd and 6th months of treatment were 1.21 ± 0.19, 1.09 ± 0.16 and 1.11 ± 0.19 pmol/L, respectively. Mean serum fT3 and fT4 levels decreased significantly at 3rd and 6th months compared to baseline levels (p < 0.01 and p < 0.01, p < 0.01 and p = 0.001, respectively). Systemic isotretinoin therapy causes significant alterations in sTFTs. Dose dependent or long-term effects of systemic isotretinoin on sTFTs needs further evaluation.

Feasibility, acceptance and long-term exercise behaviour in cancer patients: an exercise intervention by using a swinging-ring system.

PubMed

Crevenna, Richard; Cenik, Fadime; Galle, Anton; Komanadj, Tanya Sedghi; Keilani, Mohammad

2015-10-01

Aim of this pilot study was to describe feasibility and acceptance of an exercise intervention by using an unique swinging-ring system with the goal to promote long-term exercise behaviour in cancer patients. The included cancer patients (n = 13, male:f emale (m:f) = 7:6, age = 56 ± 11, range 38-74a) were invited to perform a home-based exercise intervention. All participants of this pilot study were instructed how to use the smovey® Vibroswing. They could choose how to use the swinging-ring system, for example only indoor or only outdoor (single or in a group) or both. Feasibility and acceptance were assessed after 12 months (T2). Handgrip strength (Jamar hand dynamometer) and health-related quality of life (QOL, SF-36 Health survey) were assessed at baseline (T1) and after 12 months (T2). A total of 10 (77%) patients (m:f = 5:5, 59 ± 9 years, range = 46-74) could be assessed at baseline and after 12 months. The exercise intervention showed no adverse events and was well accepted. Approximately 77% of patients of the study population have been exercising for more than 12 months. Furthermore, this intervention was able to increase handgrip strength in the participants. QOL improved as well in all domains. The results of this small pilot study indicate that regular physical exercise with this swinging-ring system seems to be safe, and to promote long-term exercise behaviour of the included patients. Furthermore, this study population showed benefits in terms of increased handgrip strength and of improved QOL.

Piston and Ring Assembly Friction Studies in Cummins 903 Engine

DTIC Science & Technology

1989-06-01

5.0 um/div, horiz = 1.0 mm/div, Sample Interval of 7.0 um 121 Cr Oxide plasma ring on Cummins kaman-Cr Oxide, non lubricated 1.88I .9B 1I .8e8 I T 48...Chromium Oxide Liner, No Lubricant 122 Cr Oxide Plasma ring on Cummins-Naman Cr Oxide, Synthetic A oil 1.88- .908 I .788 T 1 .680 N .48 f C 38" " : " • Oo

Mode-hopping mechanism generating colored noise in a magnetic tunnel junction based spin torque oscillator

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

Sharma, Raghav; Dürrenfeld, P.; Iacocca, E.

The frequency noise spectrum of a magnetic tunnel junction (MTJ) based spin torque oscillator (STO) is examined where multiple modes and mode-hopping events are observed. The frequency noise spectrum is found to consist of both white noise and 1/f frequency noise. Here, we find a systematic and similar dependence of both white noise and 1/f frequency noise on bias current and the relative angle between the reference and free layers, which changes the effective damping and hence the mode-hopping behavior in this system. The frequency at which the 1/f frequency noise changes to white noise increases as the free layermore » is aligned away from the anti-parallel orientation w.r.t the reference layer. Lastly, these results indicate that the origin of 1/f frequency noise is related to mode-hopping which produces both white noise as well as 1/f frequency noise similar to the case of ring lasers.« less

Mode-hopping mechanism generating colored noise in a magnetic tunnel junction based spin torque oscillator

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

Sharma, Raghav; Dürrenfeld, P.; Iacocca, E.

The frequency noise spectrum of a magnetic tunnel junction based spin torque oscillator is examined where multiple modes and mode-hopping events are observed. The frequency noise spectrum is found to consist of both white noise and 1/f frequency noise. We find a systematic and similar dependence of both white noise and 1/f frequency noise on bias current and the relative angle between the reference and free layers, which changes the effective damping and hence the mode-hopping behavior in this system. The frequency at which the 1/f frequency noise changes to white noise increases as the free layer is aligned awaymore » from the anti-parallel orientation w.r.t the reference layer. These results indicate that the origin of 1/f frequency noise is related to mode-hopping, which produces both white noise as well as 1/f frequency noise similar to the case of ring lasers.« less

Mode-hopping mechanism generating colored noise in a magnetic tunnel junction based spin torque oscillator

DOE PAGES

Sharma, Raghav; Dürrenfeld, P.; Iacocca, E.; ...

2014-09-29

The frequency noise spectrum of a magnetic tunnel junction (MTJ) based spin torque oscillator (STO) is examined where multiple modes and mode-hopping events are observed. The frequency noise spectrum is found to consist of both white noise and 1/f frequency noise. Here, we find a systematic and similar dependence of both white noise and 1/f frequency noise on bias current and the relative angle between the reference and free layers, which changes the effective damping and hence the mode-hopping behavior in this system. The frequency at which the 1/f frequency noise changes to white noise increases as the free layermore » is aligned away from the anti-parallel orientation w.r.t the reference layer. Lastly, these results indicate that the origin of 1/f frequency noise is related to mode-hopping which produces both white noise as well as 1/f frequency noise similar to the case of ring lasers.« less

Electrostatic forces in planetary rings

NASA Technical Reports Server (NTRS)

Goertz, C. K.; Shan, Linhua; Havnes, O.

1988-01-01

The average charge on a particle in a particle-plasma cloud, the plasma potential inside the cloud, and the Coulomb force acting on the particle are calculated. The net repulsive electrostatic force on a particle depends on the plasma density, temperature, density of particles, particle size, and the gradient of the particle density. In a uniformly dense ring the electrostatic repulsion is zero. It is also shown that the electrostatic force acts like a pressure force, that even a collisionless ring can be stable against gravitational collapse, and that a finite ring thickness does not necessarily imply a finite velocity dispersion. A simple criterion for the importance of electrostatic forces in planetary rings is derived which involves the calculation of the vertical ring thickness which would result if only electrostatic repulsion were responsible for the finite ring thickness. Electrostatic forces are entirely negligible in the main rings of Saturn and the E and G rings. They may also be negligible in the F ring. However, the Uranian rings and Jupiter's ring seem to be very much influenced by electrostatic repulsion. In fact, electrostatic forces could support a Jovian ring which is an order of magnitude more dense than observed.

Fluorine (19F) MRS and MRI in biomedicine.

PubMed

Ruiz-Cabello, Jesús; Barnett, Brad P; Bottomley, Paul A; Bulte, Jeff W M

2011-02-01

Shortly after the introduction of (1)H MRI, fluorinated molecules were tested as MR-detectable tracers or contrast agents. Many fluorinated compounds, which are nontoxic and chemically inert, are now being used in a broad range of biomedical applications, including anesthetics, chemotherapeutic agents, and molecules with high oxygen solubility for respiration and blood substitution. These compounds can be monitored by fluorine ((19)F) MRI and/or MRS, providing a noninvasive means to interrogate associated functions in biological systems. As a result of the lack of endogenous fluorine in living organisms, (19)F MRI of 'hotspots' of targeted fluorinated contrast agents has recently opened up new research avenues in molecular and cellular imaging. This includes the specific targeting and imaging of cellular surface epitopes, as well as MRI cell tracking of endogenous macrophages, injected immune cells and stem cell transplants. Copyright © 2010 John Wiley & Sons, Ltd.

Adiabatic pressure dependence of the 2.7 and 1.9 micron water vapor bands

NASA Technical Reports Server (NTRS)

Mathai, C. V.; Walls, W. L.; Broersma, S.

1977-01-01

An acoustic excitation technique is used to determine the adiabatic pressure derivative of the spectral absorptance of the 2.7 and 1.9 micron water vapor bands, and the 3.5 micron HCl band. The dependence of this derivative on thermodynamic parameters such as temperature, concentration, and pressure is evaluated. A cross-flow water vapor system is used to measure spectral absorptance. Taking F as the ratio of nonrigid to rotor line strengths, it is found that an F factor correction is needed for the 2.7 micron band. The F factor for the 1.9 micron band is also determined. In the wings of each band a wavelength can be found where the concentration dependence is predominant. Farther out in the wings a local maximum occurs for the temperature derivative. It is suggested that the pressure derivative is significant in the core of the band.

VizieR Online Data Catalog: BEST-II catalog of variables. I. Southern fields (Fruth+, 2013)

NASA Astrophysics Data System (ADS)

Fruth, T.; Cabrera, J.; Chini, R.; Csizmadia, Sz.; Dreyer, C.; Eigmuller, P.; Erikson, A.; Kabath, P.; Kirste, S.; Lemke, R.; Murphy, M.; Pasternacki, T.; Rauer, H.; Titz-Weider, R.

2014-07-01

BEST II (Berlin Exoplanet Search Telescope II) is located at the Observatorio Cerro Armazones, Chile. Since 2007, it has been operated continuously by the Institute of Planetary Research of the German Aerospace Center (DLR) in robotic mode from Berlin. The system consists of a 25cm Baker-Ritchey-Chretien telescope. The photometric data presented here were obtained with a 4k*4k Finger Lakes Instrumentation CCD (IMG-16801E1) in white light, i.e., without any photometric filter. The CCD is most sensitive at λ~650nm, and the photometric system is roughly comparable to the Johnson R-band. Three target fields, named F17, F18, and F19, were monitored intensively with BEST II in 2009 Apr 20-2009 Jul 22, 2009 Aug 19-2009 Oct 27, and 2010 Mar 24-2010 Sep 21 respectively. (2 data files).

Mechanochemical synthesis of MgF2 - MF2 composite systems (M = Ca, Sr, Ba)

NASA Astrophysics Data System (ADS)

Scholz, G.; Breitfeld, S.; Krahl, T.; Düvel, A.; Heitjans, P.; Kemnitz, E.

2015-12-01

The capability of mechanochemical synthesis for the formation of MgF2-MF2 (M: Ca, Sr, Ba) composites, solid solutions or well-defined compounds was tested applying a fluorination of different fluorine-free metal sources with NH4F directly at milling. No evidence was found for a substitution of Mg2+ with Ca2+ (Sr2+, Ba2+) ions, or vice versa, in rutile or fluorite structure. However, an equimolar ratio of Mg2+ to the second cation allows the mechanochemical synthesis of tetrafluoromagnesates, MMgF4, which is more and more hampered the smaller the radius of the cation M2+ is. BaMgF4 is formed even phase pure from the acetates, SrMgF4 can only be observed in a mixture accompanied by the binary fluorides. In addition, 19F MAS NMR spectra along with calculations of 19F isotropic chemical shift values according to the superposition model point to the formation of a metastable phase of CaMgF4, which disappears at thermal treatment and decomposes into the binary fluorides CaF2 and MgF2.

New species of Bakeria (Nematoda; Strongylida; Molineidae), new species of Falcaustra (Nematoda; Ascaridida; Kathlaniidae) and other helminths in Cnemaspis mcguirei (Sauria; Gekkonidae) from Peninsular Malaysia.

PubMed

Bursey, Charles R; Goldberg, Stephen R; Grismer, L Lee

2014-10-01

Two new nematode species, Bakeria schadi sp. nov. and Falcaustra malaysiaia sp. nov. from the gastrointestinal tract of McGuire's rock gecko, Cnemaspis mcguirei (Sauria: Gekkonidae) collected in Peninsular Malaysia are described. The two species now assigned to Bakeria are separated on the bases of male bursa type and location of the excretory pore: type II in B. schadi sp. nov. and type I in B. bakeri; location of excretory pore, anterior to nerve ring in B. schadi sp. nov. and posterior to nerve ring in B. bakeri. Falcaustra malaysiaia sp. nov. is most similar to F. chabaudi, F. concinnae, F. condorcanquii, F. barbi, F. dubia, and F. tchadi in that these 7 species possess 1 pseudosucker, 1 median papilla plus 10 pairs caudal papillae, and spicules with lengths between 1 and 2 mm. F. barbi and F. tchadi lack adcloacal papillae; the remaining 5 species possess 1 pair of adcloacal papillae. Falcaustra chabaudi is known from Nearctic salamanders; F. concinnae from Nearctic turtles; F. condorcanquii from Neotropical frogs, F. dubia from Oriental frogs, and F. malaysiaia sp. nov. from Oriental geckos. Two additional species of Nematoda were found, Cosmocerca ornata and Meteterakis singaporensis. Cnemaspis mcguirei represents a new host record for Cosmocerca ornata and Meteterakis singaporensis.

N-[4-Cyano-3-(trifluoro­meth­yl)phen­yl]-2-eth­oxy­benzamide

PubMed Central

Naveen, S.; Basappa; Manjunath, H. R.; Sridhar, M. A.; Shashidhara Prasad, J.; Rangappa, K. S.

2010-01-01

In the title compound, C17H13F3N2O2, the two aromatic rings are essentially coplanar, forming a dihedral angle of 2.78 (12)°. The non-H atoms of the eth­oxy group are coplanar with the attached ring [maximum deviation = 0.271 (3) Å]. An intra­molecular N—H⋯O hydrogen bond occurs. In the crystal structure, mol­ecules are linked by inter­molecular C—H⋯N and C—H⋯F hydrogen bonds. PMID:21587782

1,3-Bis[(5-amino-furan-2-yl)meth-yl]-3,4,5,6-tetra-hydro-pyrimidin-1-ium hexa-fluoro-phosphate.

PubMed

Akkurt, Mehmet; Akkoç, Senem; Gök, Yetkin; Tahir, Muhammad Nawaz

2013-01-01

The asymmetric unit of the title salt, C16H21N2O2 (+)·PF6 (-), contains half of the whole ion pair, which has crystallographic mirror symmetry. Two F atoms related by the mirror plane are disordered over two sites of equal occupancy. The dihedral angle between the central ring and the furan ring is 59.3 ()°. In the crystal, the anions and cations are linked through C-H⋯F inter-actions, forming a three-dimensional network.

Environmental Study of Fish Spawning and Nursery Areas in the Saint Clair-Detroit River System

DTIC Science & Technology

1986-06-01

II , EE ;I I1\\ vl I Y", I~S CLAIR0 /3 ISO A-2.8 STATh’T MILES .’f t 52: + 3 I + + 5 -,5, + + 2 I + 455o.~L + I 6 W,11 Pt Lt+ F G 31- S 4 1 5 4 , 0 {i...11904 574590 442470 1983 August 2 77 22 20 4 10878 11352 574590 442469 1984 May 1 55 19 18 4 . 574640 442519 1984 May 2 55 19 18 4 11626 12365 574591

Realistic simulations of the coupling between the protomotive force and the mechanical rotation of the F0-ATPase

PubMed Central

Mukherjee, Shayantani; Warshel, Arieh

2012-01-01

The molecular origin of the action of the F0 proton gradient-driven rotor presents a major puzzle despite significant structural advances. Although important conceptual models have provided guidelines of how such systems should work, it has been challenging to generate a structure-based molecular model using physical principles that will consistently lead to the unidirectional proton-driven rotational motion during ATP synthesis. This work uses a coarse-grained (CG) model to simulate the energetics of the F0-ATPase system in the combined space defined by the rotational coordinate and the proton transport (PTR) from the periplasmic side (P) to the cytoplasmic side (N). The model establishes the molecular origin of the rotation, showing that this effect is due to asymmetry in the energetics of the proton path rather than only the asymmetry of the interaction of the Asp on the c-ring helices and Arg on the subunit-a. The simulation provides a clear conceptual background for further exploration of the electrostatic basis of proton-driven mechanochemical systems. PMID:22927379

Synthesis, SAR and molecular docking studies of benzo[d]thiazole-hydrazones as potential antibacterial and antifungal agents.

PubMed

Zha, Gao-Feng; Leng, Jing; Darshini, N; Shubhavathi, T; Vivek, H K; Asiri, Abdullah M; Marwani, Hadi M; Rakesh, K P; Mallesha, N; Qin, Hua-Li

2017-07-15

A series of new benzo[d]thiazole-hydrazones analogues were synthesized and screened for their in vitro antibacterial and antifungal activities. The results revealed that compounds 13, 14, 15, 19, 20, 28 and 30 exhibited superior antibacterial potency compared to the reference drug chloramphenicol and rifampicin. Compounds 5, 9, 10, 11, 12, 28 and 30 were found to be good antifungal activity compared to the standard drug ketoconazole. A preliminary study of the structure-activity relationship (SAR) revealed that the antimicrobial activity depended on the effect of different substituents on the phenyl ring. The electron donating (OH and OCH 3 ) groups presented in the analogues, increase the antibacterial activity (except compound 12), interestingly, while the electron withdrawing (Cl, NO 2 , F and Br) groups increase the antifungal activity (except compound 19 and 20). In addition, analogues containing thiophene (28) and indole (30) showed good antimicrobial activities. Whereas, aliphatic analogues (24-26) shown no activities in both bacterial and fungal stains even in high concentrations (100µg/mL). Molecular docking studies were performed for all the synthesized compounds of which compounds 11, 19 and 20 showed the highest glide G-score. Copyright © 2017 Elsevier Ltd. All rights reserved.

New perspectives for undoped CaF2 scintillator as a threshold activation neutron detector

NASA Astrophysics Data System (ADS)

Sibczynski, Pawel; Dziedzic, Andrzej; Grodzicki, Krystian; Iwanowska-Hanke, Joanna; Moszyński, Marek; Swiderski, Lukasz; Syntfeld-Każuch, Agnieszka; Wolski, Dariusz; Carrel, Frédérick; Grabowski, Amélie; Hamel, Matthieu; Laine, Frederic; Sari, Adrien; Iovene, Alessandro; Tintori, Carlo; Fontana, Cristiano; Pino, Felix

2018-01-01

In this paper we present the prompt photofission neutron detection performance of undoped CaF2 scintillator using Threshold Activation Detection (TAD). The study is carried out in the frame of C-BORD Horizon 2020 project, during which an efficient toolbox for high volume freight non-intrusive inspection (NII) is under development. Technologies for radiation monitoring are the part of the project. Particularly, detection of various radiological threats on country borders plays an important significant role in Homeland Security applications. Detection of illegal transfer of Special Nuclear Material (SNM) - 235U, 233U and 239Pu - is particular due to the potential use for production of nuclear weapon as well as radiological dispersal device (RDD) V known also as a "dirty bomb". This technique relies on activation of 19F nuclei in the scintillator medium by fast neutrons and registration of high-energy β particles and γ-rays from the decay of reaction products. The radiation from SNM is detected after irradiation in order to avoid detector blinding. Despite the low 19F(n,α)16N or 19F(n,p)19O reaction cross-section, the method could be a good solution for detection of shielded nuclear material. Results obtained with the CaF2 detector were compared with the previous study done for BaF2 and 3He detector. These experimental results were obtained using 252Cf source and 9 MeV Varian Linatron M9 linear accelerator (LINAC). Finally, performance of the prompt neutron detection system based on CaF2 will be validated at Rotterdam Seaport during field trails in 2018.

76 FR 56244 - Self-Regulatory Organizations; New York Stock Exchange LLC; Notice of Filing and Immediate...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-12

... Apply to Foreign Issuers September 6, 2011. Pursuant to Section 19(b)(1) of the Securities Exchange Act... proposed rule change pursuant to Section 19(b)(3)(A)(iii) and Rule 19b-4(f)(6) thereunder so that the... to be book-entry only) must be eligible for a direct registration system (``DRS'') operated by a...

TssA forms a gp6-like ring attached to the type VI secretion sheath.

PubMed

Planamente, Sara; Salih, Osman; Manoli, Eleni; Albesa-Jové, David; Freemont, Paul S; Filloux, Alain

2016-08-01

The type VI secretion system (T6SS) is a supra-molecular bacterial complex that resembles phage tails. It is a killing machine which fires toxins into target cells upon contraction of its TssBC sheath. Here, we show that TssA1 is a T6SS component forming dodecameric ring structures whose dimensions match those of the TssBC sheath and which can accommodate the inner Hcp tube. The TssA1 ring complex binds the T6SS sheath and impacts its behaviour in vivo In the phage, the first disc of the gp18 sheath sits on a baseplate wherein gp6 is a dodecameric ring. We found remarkable sequence and structural similarities between TssA1 and gp6 C-termini, and propose that TssA1 could be a baseplate component of the T6SS Furthermore, we identified similarities between TssK1 and gp8, the former interacting with TssA1 while the latter is found in the outer radius of the gp6 ring. These observations, combined with similarities between TssF and gp6N-terminus or TssG and gp53, lead us to propose a comparative model between the phage baseplate and the T6SS. © 2016 The Authors. Published under the terms of the CC BY 4.0 license.

TANKS 18 AND 19-F EQUIPMENT GROUT FILL MATERIAL EVALUATION AND RECOMMENDATIONS

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

Stefanko, D.; Langton, C.

The United States Department of Energy (US DOE) intends to remove Tanks 18-F and 19-F at the Savannah River Site (SRS) from service. The high-level waste (HLW) tanks have been isolated from the F-area Tank Farm (FTF) facilities and will be filled with cementitious grout for the purpose of: (1) physically stabilizing the empty volumes in the tanks, (2) limiting/eliminating vertical pathways from the surface to residual waste on the bottom of the tanks, (3) providing an intruder barrier, and (4) providing an alkaline, chemical reducing environment within the closure boundary to limit solubility of residual radionuclides. Bulk waste andmore » heel waste removal equipment will remain in Tanks 18-F and 19-F when the tanks are closed. This equipment includes: mixer pumps, transfer pumps, transfer jets, equipment support masts, sampling masts and dip tube assemblies. The current Tank 18-F and 19-F closure strategy is to grout the internal void spaces in this equipment to eliminate fast vertical pathways and slow water infiltration to the residual material on the tank floor. This report documents the results of laboratory testing performed to identify a grout formulation for filling the abandoned equipment in Tanks 18-F and 19-F. The objective of this work was to formulate a flowable grout for filling internal voids of equipment that will remain in Tanks 18-F and 19-F during the final closures. This work was requested by V. A. Chander, Tank Farm Closure Engineering, in HLW-TTR-2011-008. The scope for this task is provided in the Task Technical and Quality Assurance Plan (TTQAP), SRNL-RP-2011-00587. The specific objectives of this task were to: (1) Prepare and evaluate the SRR cooling coil grout identified in WSRC-STI-2008-00298 per the TTR for this work. The cooling coil grout is a mixture of BASF MasterFlow{reg_sign} 816 cable grout (67.67 wt. %), Grade 100 ground granulated blast furnace slag (7.52 wt. %) and water (24.81 wt. %); (2) Identify equipment grout placement and performance properties; (3) Design up to 2 additional grout systems for filling the Tank 18-F and Tank 19-F equipment; (4) Prepare samples of candidate grouts and measure fresh properties, thermal properties and cured properties; (5) Recommend a grout for the Tier 1A equipment fill mock up - ADMP 4 foot high mock up, 1 inch and 2 inch pipes; (6) Support procurement of materials for the Tier 1A equipment fill mock up test; (7) Prepare samples of the recommended grout for hydraulic property measurements which can be used for comparison to values used in the F- Tank Farm Performance Assessment (PA); and (8) Document equipment fill grout data and recommendations in a report.« less

Flower colour and cytochromes P450†

PubMed Central

Tanaka, Yoshikazu; Brugliera, Filippa

2013-01-01

Cytochromes P450 play important roles in biosynthesis of flavonoids and their coloured class of compounds, anthocyanins, both of which are major floral pigments. The number of hydroxyl groups on the B-ring of anthocyanidins (the chromophores and precursors of anthocyanins) impact the anthocyanin colour, the more the bluer. The hydroxylation pattern is determined by two cytochromes P450, flavonoid 3′-hydroxylase (F3′H) and flavonoid 3′,5′-hydroxylase (F3′5′H) and thus they play a crucial role in the determination of flower colour. F3′H and F3′5′H mostly belong to CYP75B and CYP75A, respectively, except for the F3′5′Hs in Compositae that were derived from gene duplication of CYP75B and neofunctionalization. Roses and carnations lack blue/violet flower colours owing to the deficiency of F3′5′H and therefore lack the B-ring-trihydroxylated anthocyanins based upon delphinidin. Successful redirection of the anthocyanin biosynthesis pathway to delphinidin was achieved by expressing F3′5′H coding regions resulting in carnations and roses with novel blue hues that have been commercialized. Suppression of F3′5′H and F3′H in delphinidin-producing plants reduced the number of hydroxyl groups on the anthocyanidin B-ring resulting in the production of monohydroxylated anthocyanins based on pelargonidin with a shift in flower colour to orange/red. Pelargonidin biosynthesis is enhanced by additional expression of a dihydroflavonol 4-reductase that can use the monohydroxylated dihydrokaempferol (the pelargonidin precursor). Flavone synthase II (FNSII)-catalysing flavone biosynthesis from flavanones is also a P450 (CYP93B) and contributes to flower colour, because flavones act as co-pigments to anthocyanins and can cause blueing and darkening of colour. However, transgenic plants expression of a FNSII gene yielded paler flowers owing to a reduction of anthocyanins because flavanones are precursors of anthocyanins and flavones. PMID:23297355

Flower colour and cytochromes P450.

PubMed

Tanaka, Yoshikazu; Brugliera, Filippa

2013-02-19

Cytochromes P450 play important roles in biosynthesis of flavonoids and their coloured class of compounds, anthocyanins, both of which are major floral pigments. The number of hydroxyl groups on the B-ring of anthocyanidins (the chromophores and precursors of anthocyanins) impact the anthocyanin colour, the more the bluer. The hydroxylation pattern is determined by two cytochromes P450, flavonoid 3'-hydroxylase (F3'H) and flavonoid 3',5'-hydroxylase (F3'5'H) and thus they play a crucial role in the determination of flower colour. F3'H and F3'5'H mostly belong to CYP75B and CYP75A, respectively, except for the F3'5'Hs in Compositae that were derived from gene duplication of CYP75B and neofunctionalization. Roses and carnations lack blue/violet flower colours owing to the deficiency of F3'5'H and therefore lack the B-ring-trihydroxylated anthocyanins based upon delphinidin. Successful redirection of the anthocyanin biosynthesis pathway to delphinidin was achieved by expressing F3'5'H coding regions resulting in carnations and roses with novel blue hues that have been commercialized. Suppression of F3'5'H and F3'H in delphinidin-producing plants reduced the number of hydroxyl groups on the anthocyanidin B-ring resulting in the production of monohydroxylated anthocyanins based on pelargonidin with a shift in flower colour to orange/red. Pelargonidin biosynthesis is enhanced by additional expression of a dihydroflavonol 4-reductase that can use the monohydroxylated dihydrokaempferol (the pelargonidin precursor). Flavone synthase II (FNSII)-catalysing flavone biosynthesis from flavanones is also a P450 (CYP93B) and contributes to flower colour, because flavones act as co-pigments to anthocyanins and can cause blueing and darkening of colour. However, transgenic plants expression of a FNSII gene yielded paler flowers owing to a reduction of anthocyanins because flavanones are precursors of anthocyanins and flavones.

Assessing Intrarenal Non-perfusion and Vascular Leakage in Acute Kidney Injury withzz 19F MRI and Perfluorocarbon Nanoparticles

PubMed Central

Hu, Lingzhi; Chen, Junjie; Yang, Xiaoxia; Senpan, Angana; Allen, John S.; Yanaba, Noriko; Caruthers, Shelton D.; Lanza, Gregory M.; Hammerman, Marc R.; Wickline, Samuel A.

2014-01-01

Purpose We sought to develop a unique sensor-reporter approach for functional kidney imaging that employs circulating perfluorocarbon nanoparticles (PFC NPs) and 19F MRI. Methods Because the detected 19F signal intensity directly reflects local blood volume, and the 19F R1 is linearly proportional to local blood oxygen content (pO2), 19F spin density weighted and T1 weighted images were utilized to generate quantitative functional mapping in both healthy and ischemia-reperfusion (acute kidney injury, AKI) injured mouse kidneys. 1H Blood-Oxygenation-Level-Dependant (BOLD) MRI was also employed as a supplementary approach to facilitate the compressive analysis of renal circulation and its pathological changes in AKI. Results Heterogeneous blood volume distribution and intrarenal oxygenation gradient were confirmed in healthy kidneys by 19F MRI. In a mouse model of AKI, 19F MRI, in conjunction with BOLR MRI, sensitively delineated renal vascular damage and recovery. In the cortico-medullary (CM) junction region, we observed 25% lower 19F signal (p<0.05) and 70% longer 1H T2* (p<0.01) in injured kidneys compared to contralateral kidneys at 24 hours after initial ischemia-reperfusion injury. We also detected 71% higher 19F signal (p<0.01) and 40% lower 1H T2* (p<0.05) in the renal medulla region of injured kidneys compared to contralateral kidneys. Conclusion With demonstrated superior diagnostic capability, functional kidney 19F MRI using PFC NPs could serve as a new diagnostic measures for comprehensive evaluation of renal function and pathology. PMID:23929727

[The VB system: a new modular osteosynthesis material involving both screws and wires].

PubMed

Dubert, T; Valenti, P; Dinh, A; Osman, N

2002-01-01

VB is an osteosynthesis system for the stabilisation of small fragments, which combines the benefits of both wires and screws. It is a modular system comprising a threaded pin and a ring. The threaded pin is first positioned. Then a ring is grasped and opened by the progressive angulation of a screwdriver. Still anchored on the screwdriver, the ring slides easily on the pin. It is clamped on the pin by simply removing the screwdriver and the pin is then cut. This modular system includes 1.8 and 1.1 mm pins and different types of rings (threaded or non threaded, with or without collars). The system is easy to handle and can be introduced using an open or percutaneous technique, allowing compression or distraction. Our preliminary series, performed in accordance with National clinical trial protocol (Huriet) consisted of 50 cases in 24 patients (five women and 19 men) with an average age of 48 years, and a follow-up of more than six months. Fourteen cases of fractures (28 implants) were treated as emergencies (two radial heads, one capitellum, one trochlea of the humerus, seven distal radius fractures, one trapezium, two metacarpals) and 12 cases (22 implants) were elective cases: arthrodesis (one trapezo-metacarpal, one intermetacarpal, two interphalangeal, two carpal), non-union (six scaphoids, one phalangeal) and one phalangeal malunion. Hardware removal was performed in 16 cases. No implant failure has been detected. One case, a DIP arthrodesis, had a suspicion of sepsis which led to the removal of the implants at six weeks. The results of this study have convinced us of the merits of the system, which combines the advantages of both wires and screws. The system allows the user to perform either distraction or compression, and to adjust the force by hand. Compared to the fixed amount of compression produced by lag screws, this feature seems to be a real step forward.

Crystal structure of 4-fluoro-N-[2-(4-fluoro­benzo­yl)hydra­zine-1-carbono­thio­yl]benzamide

PubMed Central

Firdausiah, Syadza; Salleh Huddin, Ameera Aqeela; Hasbullah, Siti Aishah; Yamin, Bohari M.; Yusoff, Siti Fairus M.

2014-01-01

In the title compound, C15H11F2N3O2S, the dihedral angle between the fluoro­benzene rings is 88.43 (10)° and that between the central semithiocarbazide grouping is 47.00 (11)°. The dihedral angle between the amide group and attached fluoro­benzene ring is 50.52 (11)°; the equivalent angle between the carbonyl­thio­amide group and its attached ring is 12.98 (10)°. The major twists in the mol­ecule occur about the C—N—N—C bonds [torsion angle = −138.7 (2)°] and the Car—Car—C—N (ar = aromatic) bonds [−132.0 (2)°]. An intra­molecular N—H⋯O hydrogen bond occurs, which generates an S(6) ring. In the crystal, the mol­ecules are linked by N—H⋯O and N—H⋯S hydrogen bonds, generating (001) sheets. Weak C—H⋯O and C—H⋯F inter­actions are also observed. PMID:25309250

19F-perfluorocarbon-labeled human peripheral blood mononuclear cells can be detected in vivo using clinical MRI parameters in a therapeutic cell setting.

PubMed

Fink, Corby; Gaudet, Jeffrey M; Fox, Matthew S; Bhatt, Shashank; Viswanathan, Sowmya; Smith, Michael; Chin, Joseph; Foster, Paula J; Dekaban, Gregory A

2018-01-12

A 19 Fluorine ( 19 F) perfluorocarbon cell labeling agent, when employed with an appropriate cellular MRI protocol, allows for in vivo cell tracking. 19 F cellular MRI can be used to non-invasively assess the location and persistence of cell-based cancer vaccines and other cell-based therapies. This study was designed to determine the feasibility of labeling and tracking peripheral blood mononuclear cells (PBMC), a heterogeneous cell population. Under GMP-compliant conditions human PBMC were labeled with a 19 F-based MRI cell-labeling agent in a manner safe for autologous re-injection. Greater than 99% of PBMC labeled with the 19 F cell-labeling agent without affecting functionality or affecting viability. The 19 F-labeled PBMC were detected in vivo in a mouse model at the injection site and in a draining lymph node. A clinical cellular MR protocol was optimized for the detection of PBMC injected both at the surface of a porcine shank and at a depth of 1.2 cm, equivalent to depth of a human lymph node, using a dual 1 H/ 19 F dual switchable surface radio frequency coil. This study demonstrates it is feasible to label and track 19 F-labeled PBMC using clinical MRI protocols. Thus, 19 F cellular MRI represents a non-invasive imaging technique suitable to assess the effectiveness of cell-based cancer vaccines.

Design and development of MR-compatible SPECT systems for simultaneous SPECT-MR imaging of small animals

NASA Astrophysics Data System (ADS)

Tsui, Benjamin M. W.; Hugg, James W.; Xu, Jingyan; Chen, Si; Meier, Dirk; Edelstein, William; El-Sharkawy, Abdel; Wagenaar, Douglas J.; Patt, Bradley E.

2011-03-01

We describe a continuing design and development of MR-compatible SPECT systems for simultaneous SPECT-MR imaging of small animals. A first generation prototype SPECT system was designed and constructed to fit inside a MRI system with a gradient bore inner diameter of 12 cm. It consists of 3 angularly offset rings of 8 detectors (1"x1", 16x16 pixels MR-compatible solid-state CZT). A matching 24-pinhole collimator sleeve, made of a tungsten-compound, provides projections from a common FOV of ~25 mm. A birdcage RF coil for MRI data acquisition surrounds the collimator. The SPECT system was tested inside a clinical 3T MRI system. Minimal interference was observed on the simultaneously acquired SPECT and MR images. We developed a sparse-view image reconstruction method based on accurate modeling of the point response function (PRF) of each of the 24 pinholes to provide artifact-free SPECT images. The stationary SPECT system provides relatively low resolution of 3-5 mm but high geometric efficiency of 0.5- 1.2% for fast dynamic acquisition, demonstrated in a SPECT renal kinetics study using Tc-99m DTPA. Based on these results, a second generation prototype MR-compatible SPECT system with an outer diameter of 20 cm that fits inside a mid-sized preclinical MRI system is being developed. It consists of 5 rings of 19 CZT detectors. The larger ring diameter allows the use of optimized multi-pinhole collimator designs, such as high system resolution up to ~1 mm, high geometric efficiency, or lower system resolution without collimator rotation. The anticipated performance of the new system is supported by simulation data.

Nitrited-Steel Piston Rings for Engines of High Specific Power

NASA Technical Reports Server (NTRS)

Collins, John H; Bisson, Edmond E; Schmiedlin, Ralph F

1945-01-01

Stability and control characteristics determined from tests in the Langley 19-foot pressure tunnel of a 0.2375-scale model of the Douglas XA-26 airplane are compared with those measured in flight tests of a Douglas A-26b airplane. Several designs of nitrided-steel piston rings were performance-tested under variable conditions of output. The necessity of good surface finish and conformity of the ring to the bore was indicated in the preliminary tests. Nitrided-steel rings of the same dimensions as cast-iron rings operating on the original piston were unsatisfactory, and the final design was a lighter, rectangular, thin-face-width ring used on a piston having a maximum cross-head area and a revised skirt shape. Results were obtained from single-cylinder and multicylinder engine runs.

N-(4,4′-Dibromo-[1,1′-biphen­yl]-2-yl)benzamide

PubMed Central

Novina, J. Josephine; Vasuki, G.; Baheti, Abhishek; Thomas, K. R. Justin

2013-01-01

In the title compound, C19H13Br2NO, the dihedral angle between the rings of the biphenyl group is 53.59 (14)°. The ring of the benzamide group is inclined to the phenyl rings of the biphenyl group by 23.87 (15) and 75.89 (15)°. There are no significant inter­molecular inter­actions in the crystal structure. PMID:23424503

(E)-1-(2,4-Di-nitro-phen-yl)-2-(3-eth-oxy-4-hy-droxy-benzyl-idene)hydrazine.

PubMed

Fun, Hoong-Kun; Chantrapromma, Suchada; Ruanwas, Pumsak; Kobkeatthawin, Thawanrat; Chidan Kumar, C S

2014-01-01

The mol-ecule of the title hydrazine derivative, C15H14N4O6, is essentially planar, the dihedral angle between the substituted benzene rings being 2.25 (9)°. The eth-oxy and hy-droxy groups are almost coplanar with their bound benzene ring [r.m.s. deviation = 0.0153 (2) Å for the ten non-H atoms]. Intra-molecular N-H⋯O and O-H⋯Oeth-oxy hydrogen bonds generate S(6) and S(5) ring motifs, respectively. In the crystal, mol-ecules are linked by O-H⋯Onitro hydrogen bonds into chains propagating in [010]. Weak aromatic π-π inter-actions, with centroid-centroid distances of 3.8192 (19) and 4.0491 (19) Å, are also observed.

Double [4 + 2] cycloaddition reaction to approach a large acene with even-number linearly fused benzene rings: 6,9,16,19-tetraphenyl-1.20,4.5,10.11,14.15-tetrabenzooctatwistacene.

PubMed

Li, Junbo; Zhao, Yongbiao; Lu, Jing; Li, Gang; Zhang, Jingping; Zhao, Yang; Sun, Xiaowei; Zhang, Qichun

2015-01-02

It is more challenging to synthesize acenes with even-number fused benzene rings (AWEB) than acenes with odd-number fused benzene rings (AWOB) because AWEB are either synthetically asymmetric or the precursors to prepare AWEB are very difficult to obtain or to prepare from commercially available sources. In this work, we employed 2,6-naphthodiyne precursor (2) as an effective synthon to prepare a large AWEB, 6,9,16,19-tetraphenyl-1.20,4.5,10.11,14.15-tetrabenzooctatwistacene (1), through a simple, one-step, double [4 + 2] cycloaddition reaction. The physical properties of as-prepared octatwistacene (1) have been carefully studied, and the OLED performance of compound 1 was also investigated.

[Primary study on fluro [ 19F] berberine derivative for human hepatocellular carcinoma targetting in vitro].

PubMed

Zhang, Tong; Wu, Xiaoai; Cai, Huawei; Liang, Meng; Fan, Chengzhong

2017-04-01

[ 18 F]HX-01, a Fluorine-18 labeled berberine derivative, is a potential positron emission tomography (PET) tumor imaging agent, while [ 19 F]HX-01 is a nonradioactive reference substance with different energy state and has the same physical and chemical properties. In order to collect data for further study of [ 18 F]HX-01 PET imaging of hepatocellular carcinoma in vivo , this study compared the uptake of [ 19 F]HX-01 by human hepatocellular carcinoma and normal hepatocytes in vitro . The target compound, [ 19 F]HX-01, was synthesized in one step using berberrubine and 3-fluoropropyl 4-methylbenzenesulfonate. Cellular uptake and localization of [ 19 F]HX-01 were performed by a fluorescence microscope in human hepatocellular carcinoma HepG2, SMMC-7721 and human normal hepatocyte HL-7702. Cellular proliferation inhibition and cell cytotoxicity assay of the [ 19 F]HX-01 were conducted using cell counting kit-8 (CCK-8) on HepG2, SMMC-7721 and HL-7702 cells. Fluorescent microscopy showed that the combining ability of [ 19 F]HX-01 to the carcinoma SMMC-7721 and HepG2 was higher than that to the normal HL-7702. Cellular proliferation inhibition assay demonstrated that [ 19 F]HX-01 leaded to a dose-dependent inhibition on SMMC-7721, HepG2, and HL-7702 proliferation. Cell cytotoxicity assay presented that the cytotoxicity of [ 19 F]HX-01 to SMMC-7721 and HepG2 was obviously higher than that to HL-7702. This in vitro study showed that [ 19 F]HX-01 had a higher selectivity on human hepatocellular carcinoma cells (SMMC-7721, HepG2) but has less toxicity to normal hepatocytes (HL-7702). This could set up the idea that the radioactive reference substance [ 18 F]HX-01 may be worthy of further development as a potential molecular probe targeting human hepatocellular carcinoma using PET.

Metabolites of 5F-AKB-48, a synthetic cannabinoid receptor agonist, identified in human urine and liver microsomal preparations using liquid chromatography high-resolution mass spectrometry.

PubMed

Holm, Niels Bjerre; Pedersen, Anders Just; Dalsgaard, Petur Weihe; Linnet, Kristian

2015-03-01

New types of synthetic cannabinoid designer drugs are constantly introduced to the illicit drug market to circumvent legislation. Recently, N-​(1-Adamant​yl)-​1-​(5-​fluoropentyl)-​1H-​indazole-​3-​carboxamide (5F-AKB-48), also known as 5F-APINACA, was identified as an adulterant in herbal products. This compound deviates from earlier JHW-type synthetic cannabinoids by having an indazole ring connected to an adamantyl group via a carboxamide linkage. Synthetic cannabinoids are completely metabolized, and identification of the metabolites is thus crucial when using urine as the sample matrix. Using an authentic urine sample and high-resolution accurate-mass Fourier transform Orbitrap mass spectrometry, we identified 16 phase-I metabolites of 5F-AKB-48. The modifications included mono-, di-, and trihydroxylation on the adamantyl ring alone or in combination with hydroxylation on the N-fluoropentylindazole moiety, dealkylation of the N-fluoropentyl side chain, and oxidative loss of fluorine as well as combinations thereof. The results were compared to human liver microsomal (HLM) incubations, which predominantly showed time-dependent formation of mono-, di-, and trihydroxylated metabolites having the hydroxyl groups on the adamantyl ring. The results presented here may be used to select metabolites specific of 5F-AKB-48 for use in clinical and forensic screening. Copyright © 2014 John Wiley & Sons, Ltd.

Molecular building kit of fused-proline-derived peptide mimetics allowing specific adjustment of the dihedral Psi angle.

PubMed

Einsiedel, Juergen; Lanig, Harald; Waibel, Reiner; Gmeiner, Peter

2007-11-23

Proline-derived peptide mimetics have become an area of paramount importance in peptide and protein chemistry. Since protein crystal structures frequently display Psi angles of 140-170 degrees for prolyl moieties, our intention was to design a completely novel series of 2,3-fused-proline-derived lactams covering this particular conformational space. Extending our recently described toolset of spirocyclic reverse-turn mimetics, we synthesized pyrrolidinyl-fused seven-, eight-, and nine-membered unsaturated lactam model peptides taking advantage of Grubbs' ring-closing metathesis. Investigating the seven-membered lactam 3a by means of IR and NMR spectroscopy and semiempirical molecular dynamics simulations, we could not observe a U-turn conformation; however, increasing the ring size to give eight- and nine-membered congeners revealed moderate and high type IotaIota beta-turn inducing properties. Interestingly, the conformational properties of our model systems depend on both the ring size of the fused dehydro-Freidinger lactam and the position of the endocyclic double bond. Superior reverse-turn inducing properties could be observed for the fused azacyclononenone 3e. According to diagnostic transanular NOEs, a discrete folding principle of the lactam ring strongly deviating from the regioisomeric lactams 3c,f explains the conformational behavior. Hence, we were able to establish a molecular building kit that allows adjustments of a wide range of naturally occurring proline Psi angles and thus can be exploited to probe molecular recognition and functional properties of biological systems.

NMR study of spin dynamics in mesoscopic molecular clusters

NASA Astrophysics Data System (ADS)

Borsa, Ferdinando

1998-03-01

Recent published and umpublished work regarding the magnetic properties and the spin dynamics of molecules containing rings of 6,8 and 10 spins and of molecules containing clusters of 8 and 12 spins are reviewed. The 1H nuclear spin-lattice relaxation rate (NSLR) and the Muon Spin Resonance relaxation in Mn12 (A.Lascialfari, D.Gatteschi, F.Borsa, A.Shastri, Z.H.Jang and P.Carretta, Phys.Rev. B 1 January 1998) and Fe8 clusters are presented and discussed with regards to the high temperature spin dynamics of the Mn (Fe) magnetic moments and with regards to the low temperature superparamagnetic behavior. 1H and 63Cu NMR results are presented for two "quantum" spin rings : Cu6 and Cu8. The Cu6 is a weakly coupled (J/k=60K) ferromagnetic S=1/2 spin ring while Cu8 is a strongly coupled (J/k greater than 400K) antiferromagnetic S=1/2 spin ring.The dependence of the NSRL from temperature and from applied magnetic field are analyzed in terms of the calculated magnetic energy levels of the magnetic ring. The values of the energy gap between the ground state and the first excited state are extracted from the exponential decrease of the NSLR as the temperature is lowered. The results in the Cu ( S=1/2) "quantum" rings are compared with the results in "quantum" chains and ladders and with the results in "classical" Fe (S=5/2) antiferromagnetic rings : Fe6 and Fe10 (A.Lascialfari, D.Gatteschi, F.Borsa and A.Cornia , Phys.Rev. 55B,14341,1997) ).

2,2'-[2,4-Bis(naphthalen-1-yl)cyclo-butane-1,3-di-yl]bis-(1-methyl-pyridinium) diiodide: thermal-induced [2 + 2] cyclo-addition reaction of a heterostilbene.

PubMed

Chantrapromma, Suchada; Chanawanno, Kullapa; Boonnak, Nawong; Fun, Hoong-Kun

2012-01-01

The asymmetric unit of the title compound, C(36)H(32)N(2) (2+)·2I(-), consists of one half-mol-ecule of the cation and one I(-) anion. The cation is located on an inversion centre. The dihedral angle between the pyridinium ring and the naphthalene ring system in the asymmetric unit is 19.01 (14)°. In the crystal, the cations and the anions are linked by C-H⋯I inter-actions into a layer parallel to the bc plane. Intra- and inter-molecular π-π inter-actions with centroid-centroid distances of 3.533 (2)-3.807 (2) Å are also observed.

Analysis of Simultaneous Polar Fox II Backscatter and Ionospheric Sounding Data

DTIC Science & Technology

latitudes where vertical soundings show spread-E and -F. Those regions appear to be identical to the auroral E (night E) layer and ’ plasma ring ’ F layer known to be associated with the auroral oval.

SU-F-I-08: CT Image Ring Artifact Reduction Based On Prior Image

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

Yuan, C; Qi, H; Chen, Z

Purpose: In computed tomography (CT) system, CT images with ring artifacts will be reconstructed when some adjacent bins of detector don’t work. The ring artifacts severely degrade CT image quality. We present a useful CT ring artifacts reduction based on projection data correction, aiming at estimating the missing data of projection data accurately, thus removing the ring artifacts of CT images. Methods: The method consists of ten steps: 1) Identification of abnormal pixel line in projection sinogram; 2) Linear interpolation within the pixel line of projection sinogram; 3) FBP reconstruction using interpolated projection data; 4) Filtering FBP image using meanmore » filter; 5) Forwarding projection of filtered FBP image; 6) Subtraction forwarded projection from original projection; 7) Linear interpolation of abnormal pixel line area in the subtraction projection; 8) Adding the interpolated subtraction projection on the forwarded projection; 9) FBP reconstruction using corrected projection data; 10) Return to step 4 until the pre-set iteration number is reached. The method is validated on simulated and real data to restore missing projection data and reconstruct ring artifact-free CT images. Results: We have studied impact of amount of dead bins of CT detector on the accuracy of missing data estimation in projection sinogram. For the simulated case with a resolution of 256 by 256 Shepp-Logan phantom, three iterations are sufficient to restore projection data and reconstruct ring artifact-free images when the dead bins rating is under 30%. The dead-bin-induced artifacts are substantially reduced. More iteration number is needed to reconstruct satisfactory images while the rating of dead bins increases. Similar results were found for a real head phantom case. Conclusion: A practical CT image ring artifact correction scheme based on projection data is developed. This method can produce ring artifact-free CT images feasibly and effectively.« less

^2H(^18F,p)^19F Study at 6 MeV/u

NASA Astrophysics Data System (ADS)

Kozub, R. L.; Nesaraja, C. D.; Moazen, B. H.; Scott, J. P.; Bardayan, D. W.; Blackmon, J. C.; Gross, C. J.; Shapira, D.; Smith, M. S.; Batchelder, J. C.; Brune, C. R.; Champagne, A. E.; Sahin, L.; Cizewski, J. A.; Thomas, J. S.; Davinson, T.; Woods, P. J.; Greife, U.; Jewett, C.; Livesay, R. J.; Ma, Z.; Parker, P. D.

2003-04-01

The degree to which the (p,α) and (p,γ) reactions destroy ^18F at temperatures ˜1-4 x 10^8 K is important for understanding the synthesis of nuclei in nova explosions and for using ^18F as a monitor of nova mechanisms in gamma ray astronomy. The reactions are dominated by low-lying proton resonances near the ^18F+p threshold (E_x=6.411 MeV excitation energy in ^19Ne). To gain further information about these resonances, we have used the inverse ^18F(d,p)^19F neutron transfer reaction at the Holifield Radioactive Ion Beam Facility to selectively populate corresponding mirror states in ^19F. Proton angular distributions were measured for states in ^19F in the excitation energy range 0-9 MeV. Results and implications for the ^18F+p reactions and nuclear structure will be presented. ^1Supported by DOE. ^2ORNL is managed by UT-Battelle, LLC, for the USDOE.

Production Engineering for Growth of Synthetic Calcite Polarizer Material

DTIC Science & Technology

1974-08-01

AD-A008 043 PRODUCTION ENGINEERING FOR GROWTH OF SYNTHETIC CALCITE POLARIZER MATERIAL Roger F. Belt, et al Litton Systems...Production Bngin««ring for Growth of Synthetic Calcit « Polarizer Material I. RCCIPItNT’tCATALOO NUMMN i. T.vpc or ncpoMT • rtmoo covtnto Final Report...VOKOt (CanlliMit en »xift •id« II ntffrt Kid Idtnlllr br block iwmbmr) Crystal Growth Hydrothermal Growth Calcite Polarizers 30. AtSTHACT

Unclassified Publications of Lincoln Laboratory, 1 January - 31 December 1995; Volume 21.

DTIC Science & Technology

1995-12-01

Air Defense Systems Weiner, S.D. Cebula , D.P. 27 Nov. 1995 ADA301812 1024 Temperature Dependence of Large Polaron Superconductivity Dionne, G.F...No. 2, April 1995, pp. 534-542 6853 Laser Physics Kelley, P.L. Chapter in Zayhowski, JJ . Encyclopedia of Applied Physics, Vol. 8, 1994, pp. 299...Diode Lasers Fabricated by ECR-JJ3AE 7127A Stability and Timing Maintenance in Soliton Transmission and Storage Rings Zayhowski, JJ

19F NMR ligand perturbation studies on 6,7-bis(trifluoromethyl)-8-ribityllumazine-7-hydrates and the lumazine synthase complex of Bacillus subtilis. Site-directed mutagenesis changes the mechanism and the stereoselectivity of the catalyzed haloform-type reaction.

PubMed

Scheuring, J; Kugelbrey, K; Weinkauf, S; Cushman, M; Bacher, A; Fischer, M

2001-06-01

The riboflavin synthase/lumazine synthase complex of Bacillus subtilis catalyzes the last two steps in riboflavin biosynthesis. The protein comprises a capsid of 60 beta subunits with lumazine synthase activity and a core of three alpha subunits with riboflavin synthase activity. The beta subunits catalyze the formation of 6,7-dimethyl-8-ribityllumazine (3) from 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione (1) and 3,4-dihydroxy-2-butanone 4-phosphate (2). Complexes of recombinant lumazine synthase (beta(60) capsids) with 6-trifluoromethyl-7-oxo-8-ribityllumazine (10) as well as 7S- or 7R-6,7-bistrifluoromethyl-8-ribityllumazine hydrate (11) were studied by (19)F NMR spectroscopy. Despite the large molecular weight of approximately 960 kDa of the protein, spectra with separated signals of free and bound ligand could be obtained. An unusually large shift difference of 8 ppm was observed between the 7-trifluoromethyl signals of free and bound ligand for epimer B of 11 and the enzyme. The signal is sensitive to the replacement of amino acid residues F22 and H88. Lumazine synthase catalyzes the elimination of the 7-trifluoromethyl group of R-diastereomer epimer A in a haloform-like reaction. The elimination reaction is also catalyzed by F22 mutants. The H88R mutant displays an opposite stereoselectivity for epimer B and a greatly enhanced reaction rate. From a model of the epimers in the active site of the protein, the main function of the side chain of F22 seems to be to keep the substrate ring in the correct position. H88 is in a position suited to act as proton acceptor in both the physiological as well as the haloform reaction. A different mechanism of the haloform-reaction is proposed in the case of the H88R mutant, initiated by hydrogen bonding of the 7-trifluorormethyl group and the guanidinium group of the arginine residue.

N-(4-Meth-oxy-phen-yl)-6-methyl-2-phenyl-5-{[4-(tri-fluoro-meth-yl)anilino]meth-yl}pyrimidin-4-amine.

PubMed

Cieplik, Jerzy; Pluta, Janusz; Bryndal, Iwona; Lis, Tadeusz

2013-11-27

The title compound, C26H23F3N4O, crystallizes with two symmetry-independent mol-ecules in the asymmetric unit, denoted A and B, which differ mainly in the rotation of the meth-oxy-phenyl ring. The -CF3 group of mol-ecule B is disordered by rotation, with the F atoms split over two sets of sites; the occupancy factor for the major component is 0.853 (4). The dihedral angles between the pyrimidine ring and the attached phenyl, meth-oxy-phenyl and tri-fluoro-methyl-phenyl rings are 8.1 (2), 37.5 (2) and 70.7 (2)°, respectively, in mol-ecule A, and 9.3 (2), 5.3 (2) and 79.7 (2)° in mol-ecule B. An intra-molecular N-H⋯N hydrogen bond occurs in each mol-ecule. In the crystal, two crystallographically independent mol-ecules associate into a dimer via a pair of N-H⋯N hydrogen bonds, with a resulting R 2 (2)(12) ring motif and π-π stacking inter-actions [centroid-centroid distance = 3.517 (4) Å] between the pyrimidine rings. For the A mol-ecules, there are inter-molecular C-H⋯O hydrogen bonds between an aryl C atom of meth-oxy-phenyl ring and a meth-oxy O atom of an adjacent mol-ecule. A similar inter-action is lacking in the B mol-ecules.

Scintillating C Ring

NASA Image and Video Library

2007-01-16

Both luminous and translucent, the C ring sweeps out of the darkness of Saturn's shadow and obscures the planet at lower left. The ring is characterized by broad, isolated bright areas, or "plateaus," surrounded by fainter material. This view looks toward the unlit side of the rings from about 19 degrees above the ringplane. North on Saturn is up. The dark, inner B ring is seen at lower right. The image was taken in visible light with the Cassini spacecraft wide-angle camera on Dec. 15, 2006 at a distance of approximately 632,000 kilometers (393,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 56 degrees. Image scale is 34 kilometers (21 miles) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA08855

Density functional theory study on aqueous aluminum-fluoride complexes: exploration of the intrinsic relationship between water-exchange rate constants and structural parameters for monomer aluminum complexes.

PubMed

Jin, Xiaoyan; Qian, Zhaosheng; Lu, Bangmei; Yang, Wenjing; Bi, Shuping

2011-01-01

Density functional theory (DFT) calculation is carried out to investigate the structures, (19)F and (27)Al NMR chemical shifts of aqueous Al-F complexes and their water-exchange reactions. The following investigations are performed in this paper: (1) the microscopic properties of typical aqueous Al-F complexes are obtained at the level of B3LYP/6-311+G**. Al-OH(2) bond lengths increase with F(-) replacing inner-sphere H(2)O progressively, indicating labilizing effect of F(-) ligand. The Al-OH(2) distance trans to fluoride is longer than other Al-OH(2) distance, accounting for trans effect of F(-) ligand. (19)F and (27)Al NMR chemical shifts are calculated using GIAO method at the HF/6-311+G** level relative to F(H(2)O)(6)(-) and Al(H(2)O)(6)(3+) references, respectively. The results are consistent with available experimental values; (2) the dissociative (D) activated mechanism is observed by modeling water-exchange reaction for [Al(H(2)O)(6-i)F(i)]((3-i)+) (i = 1-4). The activation energy barriers are found to decrease with increasing F(-) substitution, which is in line with experimental rate constants (k(ex)). The log k(ex) of AlF(3)(H(2)O)(3)(0) and AlF(4)(H(2)O)(2)(-) are predicted by three ways. The results indicate that the correlation between log k(ex) and Al-O bond length as well as the given transmission coefficient allows experimental rate constants to be predicted, whereas the correlation between log k(ex) and activation free energy is poor; (3) the environmental significance of this work is elucidated by the extension toward three fields, that is, polyaluminum system, monomer Al-organic system and other metal ions system with high charge-to-radius ratio.

Oral immunization with F4 fimbriae and CpG formulated with carboxymethyl starch enhances F4-specific mucosal immune response and modulates Th1 and Th2 cytokines in weaned pigs.

PubMed

Delisle, Benjamin; Calinescu, Carmen; Mateescu, Mircea Alexandru; Fairbrother, John Morris; Nadeau, Éric

2012-01-01

F4 fimbriae are a potential candidate for an oral subunit vaccine for prevention of post-weaning diarrhea in swine due to infection with F4-positive enterotoxigenic Escherichia coli. However, large quantities of F4 fimbriae are required to induce a specific antibody response. The aim of the present study was to evaluate the effect of supplementation of F4 fimbriae with Cytosine-phosphate-Guanosine-oligodeoxynucleotide (CpG-A D19) or with complete cholera toxin (CT) as adjuvants on the F4-specific antibody response and cytokine production in weaned pigs following oral administration of F4 fimbrial antigen formulated with Carboxymethyl Starch (CMS). Oral dosage forms of F4 fimbriae alone or supplemented with CpG-A D19 or with CT were formulated with CMS as monolithic tablets, obtained by direct compression, and administered to weaned pigs. Blood and faecal samples were collected to determine the systemic and mucosal immune status of animals at various times until necropsy. During necropsy, contents of the jejunum and ileum were collected for determination of mucosal F4 specific antibodies. Segments of jejunum and ileum were also used to measure mRNA cytokine production. The presence of CpG in the formulation of the fimbriae significantly increased F4-specific immunoglobulin (Ig) IgM and IgG levels in intestinal secretions, and enhanced Th1 (Interferon-gamma / IFN-γ, Tumour Necrosis Factor-alpha / TNF-α, Interleukin-12p40 / IL-12p40, IL-1β) and Th2 (IL-4, IL-6) cytokine production in intestinal tissues. Supplementation with CT did not result in induction of F4-specific antibodies in secretions, although a significant Th1 response (IFN-α, IFN-γ, IL-18) was detected in tissues. Neither F4-specific systemic antibodies, nor intestinally secreted IgA were detected throughout the immunization trial for all groups. CpG-A D19 appeared to be a promising adjuvant for an oral F4 subunit vaccine formulated with CMS excipient as monolithic tablets. This matrix afforded gastro-protection and delivered the F4 fimbriae at their intestinal sites.

A map-based determination of the nature of Beta Delphini

NASA Technical Reports Server (NTRS)

Gatewood, George; Castelaz, Michael; Persinger, Timothy; Stein, John; Demarque, Pierre

1989-01-01

The Beta Delphini binary system presents a stringent test of the theory of stellar evolution. Improved parallax and component masses are found for its giant (F5 III and F5 IV) stars. A study of the evolutionary status of the system indicates it to be 1.9 Gyr (1.9 billion years) old and to have a metallicity of approximately 1.5 times that of the Sun. The perturbation due to the 26.6 yr orbital motion is clearly shown in this 2.2 yr study and allows the most precise determination of the relative masses of the component stars to date. The next few months present an unusual opportunity for orbital study as the system passes through periastron. Two of the reference stars are found to have distances of less than 100 parsecs.

First Airborne Lidar Measurements of Methane and Carbon Dioxide Applying the MERLIN Demonstrator CHARM-F

NASA Astrophysics Data System (ADS)

Amediek, Axel; Büdenbender, Christian; Ehret, Gerhard; Fix, Andreas; Gerbig, Christoph; Kiemle, Chritstoph; Quatrevalet, Mathieu; Wirth, Martin

2016-04-01

CHARM-F is the new airborne four-wavelengths lidar for simultaneous soundings of atmospheric CO2 and CH4. Due to its high technological conformity it is also a demonstrator for MERLIN, the French-German satellite mission providing a methane lidar. MERLIN's Preliminary Design Review was successfully passed recently. The launch is planned for 2020. First CHARM-F measurements were performed in Spring 2015 onboard the German research aircraft HALO. The aircraft's maximum flight altitude of 15 km and special features of the lidar, such as a relatively large laser ground spot, result in data similar to those obtained by a spaceborne system. The CHARM-F and MERLIN lidars are designed in the IPDA (integrated path differential absorption) configuration using short double pulses, which gives column averaged gas mixing ratios between the system and ground. The successfully completed CHARM-F flight measurements provide a valuable dataset, which supports the retrieval algorithm development for MERLIN notably. Furthermore, the dataset allows detailed analyses of measurement sensitivities, general studies on the IPDA principle and on system design questions. These activities are supported by another instrument onboard the aircraft during the flight campaign: a cavity ring down spectrometer, providing in-situ data of carbon dioxide, methane and water vapor with high accuracy and precision, which is ideal for validation purposes of the aircraft lidar. For the near future, detailed characterizations of CHARM-F are planned, further support of the MERLIN design, as well as the scientific aircraft campaign CoMet.

Facile synthesis of AIE-active amphiphilic polymers: Self-assembly and biological imaging applications.

PubMed

Long, Zi; Liu, Meiying; Wang, Ke; Deng, Fengjie; Xu, Dazhuang; Liu, Liangji; Wan, Yiqun; Zhang, Xiaoyong; Wei, Yen

2016-09-01

In this work, we reported a rather facile method for fabrication of ultrabright, well dispersible and biocompatible fluorescent organic nanoparticles (FONs) with aggregation-induced emission (AIE) properties through combination of esterification and ring-opening reaction. The hydroxyl groups of Pluronic F127 was first reacted with the chloride of trimellitic anhydride chloride (TMAC), and its anhydride groups were further reacted with the amino groups of amino-terminated AIE dye (PhNH2) through ring-opening reaction. The optical properties, biocompatibility as well as cell uptake behavior of these obtained AIE-active nanoparticles (F127-TMAC-PhNH2 FONs) were examined by a series of characterization techniques and assays. We demonstrated that uniform organic nanoparticles with high water dispersibility, strong luminescence and desirable biocompatibility can be facilely obtained, which are promising for biological imaging applications. More importantly, a number of carboxyl groups were introduced into these AIE-active nanoparticles, which can be further utilized for further conjugation reaction and carrying anticancer drugs such as cisplatin. Therefore, the strategy of described in this work should be a simple and useful route for fabrication of multifunctional AIE-active luminescent nanotheranostic systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Twin disk composite flywheel

NASA Astrophysics Data System (ADS)

Ginsburg, B. R.

The design criteria, materials, and initial test results of composite flywheels produced under DOE/Sandia contract are reported. The flywheels were required to store from 1-5 kWh with a total energy density of 80 W-h/kg at the maximum operational speed. The maximum diameter was set at 0.6 m, coupled to a maximum thickness of 0.2 m. A maximum running time at full speed of 1000 hr, in addition to a 10,000 cycle lifetime was mandated, together with a radial overlap in the material. The unit selected was a circumferentially wound composite rim made of graphite/epoxy mounted on an aluminum mandrel ring connected to an aluminum hub consisting of two constant stress disks. A tangentially wound graphite/epoxy overlap covered the rings. All conditions, i.e., rotation at 22,000 rpm and a measured storage of 1.94 kWh were verified in the first test series, although a second flywheel failed in subsequent tests when the temperature was inadvertantly allowed to rise from 15 F to over 200 F. Retest of the first flywheel again satisfied design goals. The units are considered as ideal for coupling with solar energy and wind turbine systems.

Exocometary gas in the HD 181327 debris ring

NASA Astrophysics Data System (ADS)

Marino, S.; Matrà, L.; Stark, C.; Wyatt, M. C.; Casassus, S.; Kennedy, G.; Rodriguez, D.; Zuckerman, B.; Perez, S.; Dent, W. R. F.; Kuchner, M.; Hughes, A. M.; Schneider, G.; Steele, A.; Roberge, A.; Donaldson, J.; Nesvold, E.

2016-08-01

An increasing number of observations have shown that gaseous debris discs are not an exception. However, until now, we only knew of cases around A stars. Here we present the first detection of 12CO (2-1) disc emission around an F star, HD 181327, obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) observations at 1.3 mm. The continuum and CO emission are resolved into an axisymmetric disc with ring-like morphology. Using a Markov chain Monte Carlo method coupled with radiative transfer calculations, we study the dust and CO mass distribution. We find the dust is distributed in a ring with a radius of 86.0 ± 0.4 au and a radial width of 23.2 ± 1.0 au. At this frequency, the ring radius is smaller than in the optical, revealing grain size segregation expected due to radiation pressure. We also report on the detection of low-level continuum emission beyond the main ring out to ˜200 au. We model the CO emission in the non-local thermodynamic equilibrium regime and we find that the CO is co-located with the dust, with a total CO gas mass ranging between 1.2 × 10-6 M⊕ and 2.9 × 10-6 M⊕, depending on the gas kinetic temperature and collisional partners densities. The CO densities and location suggest a secondary origin, I.e. released from icy planetesimals in the ring. We derive a CO+CO2 cometary composition that is consistent with Solar system comets. Due to the low gas densities, it is unlikely that the gas is shaping the dust distribution.

Stochastic events may lead to accretion in Saturn's rings

NASA Astrophysics Data System (ADS)

Esposito, Larry W.

Stochastic events may lead to accretion in Saturn's rings Larry W. Esposito LASP, University of Colorado UVIS occultations indicate accretion is triggered at the B ring edge, in strong density waves in ring A and in the F ring. Moons may trigger accretion by streamline crowding (Lewis & Stewart); which enhances collisions, leading to accretion; increasing random velocities; leading to more collisions and more accretion. Cassini occultations of these strongly perturbed locations show not only accretion but also disaggregation, with time scales of hours to weeks. The collisions may lead to temporary aggregations via stochastic events: collisions can compress unconsolidated objects, trigger adhesion or bring small pieces into contact with larger or higher-density seeds. Disaggregation then can follow from disruptive collisions or tidal shedding. In the accretion/disruption balance, increased random motions could eventually give the upper hand to disruption. . . just as `irrational exuberance' can lead to financial panic in the economy; or the overpopulation of hares can lead to boom-and-bust in the population of foxes. I present a simple predator-prey model. This system's unstable equilibrium can similarly give rise to episodic cycles in accretion: explaining why the observable ring features that indicate embedded objects have been increasing since the beginning of Cassini's observations of Saturn in 2004. Unlike other interpretations of the peculiar events seen near Saturn Equinox, I emphasize the kinetic description of particle interactions rather than a fluid instability approach; and the dominance of stochastic events involving individual aggregates over free and/or driven modes in a flat disk.

Structural investigation of α-LaZr2F11 by coupling X-ray powder diffraction, 19F solid state NMR and DFT calculations

NASA Astrophysics Data System (ADS)

Martineau, Charlotte; Legein, Christophe; Body, Monique; Péron, Olivier; Boulard, Brigitte; Fayon, Franck

2013-03-01

α-LaZr2F11 has been synthesized by solid state reaction. Its crystal structure has been refined from X-ray powder diffraction data (space group no. 72 Ibam, a=7.785(1) Å, b=10.086(1) Å and c=11.102(1) Å). α-LaZr2F11 contains one La, one Zr and four F inequivalent crystallographic sites. F3 and F4 are shared between one ZrF73- polyhedron and one LaF85- polyhedron, while F1 and F2 bridge two ZrF73- polyhedra. 19F 1D MAS NMR spectra of α-LaZr2F11 are in agreement with the proposed structural model. Assignment of the 19F resonances to the corresponding crystallographic sites has been performed on the basis of both their relative intensities and their correlation patterns in a 19F 2D dipolar-based double-quantum recoupling MAS NMR spectrum. DFT calculations of the 19F chemical shielding tensors have been performed using the GIPAW method implemented in the NMR-CASTEP code, for the experimental structure and two PBE-DFT geometry optimized structures of α-LaZr2F11 (atomic position optimization and full geometry optimization with rescaling of the unit cell volume to the experimental value). Computations were done with and without using a modified La pseudopotential allowing the treatment of the 4f localized empty orbitals of La3+. A relatively nice agreement between the experimental 19F isotropic and anisotropic chemical shifts and the values calculated for the proposed structural model is obtained.

A study of the possible effect of a thermal post cure on the mechanical properties of the 404 carbon-phenolic ring of the space shuttle solid rocket motor nozzle

NASA Technical Reports Server (NTRS)

Giardini, A. A.

1986-01-01

Erratic pockets of erosion have occurred on the inner perimeter of the 404 rocket nozzle ring during liftoff firing. It is thought that it may be caused by pockets of volatile matter entrapped during manufacture. A thermal post cure was suggested as a possible means of outgassing such pockets, if they in fact do exist. To confirm an outgassing during a post cure and to establish a working upper temperature limit, thermal gravimetric and differential calorimetric analyses were made on a number of samples from two 404 rings supplied by the manufacturer. Continuous weight loss was observed over the temperature range explored (750 F) indicating outgassing, and a strong exothermic reaction occurs beginning about 390 F. Thus, an upper post cure temperature of 350 F is recommended. To determine the possible effect of a post cure on physical properties, the following tests will be made on matched sets of cured and post cured material: x-radiography (internal structure), linear dimensions, weight, porosity, cross ply thermal expansion, drop and double notch shear strengths, and tensional strength in the ply direction.

Demonstration of tumor-selective retention of fluorinated nitroimidazole probes by /sup 19/F magnetic resonance spectroscopy in vivo

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

Maxwell, R.J.; Workman, P.; Griffiths, J.R.

1989-04-01

We have evaluated two fluorinated misonidazole analogues, Ro 07-0741 and CCI-103F, as potential probes for the non-invasive identification of hypoxic tumor cells by /sup 19/F magnetic resonance spectroscopy (MRS) in vivo. The equipment used was a 1.9 T Oxford Research Systems TMR-32 spectrometer, fitted with a 15 mm diameter surface coil. Signal was readily detectable, with similar intensity from EMT6 tumor, liver, and brain at early times (1-2 hr) after i.v. injection in BALB/c mice, indicative of an initial uniform biodistribution of parent probes. At later times (5-10 hr) there was a progressive reduction in signal intensity from brain andmore » liver, but tumor levels remained constant or declined more slowly. This is illustrated by tumor/brain ratios at 6-7 hr of 2.9 (Ro 07-0741) and 4.2 (CCI-103F). In 4/5 mice analyzed at 20-24 hr after Ro 07-0741, and 1/2 following CCI-103F, tumor signal remained detectable. This occurred in the absence of parent probe as measured by HPLC, suggesting the involvement of a product of nitroreductive bioactivation. Studies with KHT and RIF-1 tumors in C3H/He mice showed a similar trend but retention in RIF-1 was less dramatic, and this was consistent with the known hypoxic fractions and comparative in vivo nitroreductase activities. These promising results support the continuing development of /sup 19/F nitroimidazole probes for non-invasive identification of hypoxic cells in vivo.« less

Surging Across the Rings

NASA Image and Video Library

2007-07-26

A surge in brightness appears on the rings directly opposite the Sun from the Cassini spacecraft. This "opposition surge" travels across the rings as the spacecraft watches. This view looks toward the sunlit side of the rings from about 9 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on June 12, 2007 using a spectral filter sensitive to wavelengths of infrared light centered at 853 nanometers. The view was acquired at a distance of approximately 524,374 kilometers (325,830 miles) from Saturn. Image scale is 31 kilometers (19 miles) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA08992

(E)-1-(2,4-Di­nitro­phen­yl)-2-(3-eth­oxy-4-hy­droxy­benzyl­idene)hydrazine

PubMed Central

Fun, Hoong-Kun; Chantrapromma, Suchada; Ruanwas, Pumsak; Kobkeatthawin, Thawanrat; Chidan Kumar, C. S.

2014-01-01

The mol­ecule of the title hydrazine derivative, C15H14N4O6, is essentially planar, the dihedral angle between the substituted benzene rings being 2.25 (9)°. The eth­oxy and hy­droxy groups are almost coplanar with their bound benzene ring [r.m.s. deviation = 0.0153 (2) Å for the ten non-H atoms]. Intra­molecular N—H⋯O and O—H⋯Oeth­oxy hydrogen bonds generate S(6) and S(5) ring motifs, respectively. In the crystal, mol­ecules are linked by O—H⋯Onitro hydrogen bonds into chains propagating in [010]. Weak aromatic π–π inter­actions, with centroid–centroid distances of 3.8192 (19) and 4.0491 (19) Å, are also observed. PMID:24527018

40 CFR 86.405-78 - Measurement system.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 19 2013-07-01 2013-07-01 false Measurement system. 86.405-78 Section... 1978 and Later New Motorcycles, General Provisions § 86.405-78 Measurement system. (a) This subpart and subpart F have been written using System International (SI) units. SI units will be used to determine...

Syntheses and multi-NMR study of fac- and mer-OsO(3)F(2)(NCCH(3)) and the X-ray crystal structure (n = 2) and Raman spectrum (n = 0) of fac-OsO(3)F(2)(NCCH(3)).nCH(3)CN.

PubMed

Hughes, Michael J; Gerken, Michael; Mercier, Hélène P A; Schrobilgen, Gary J

2010-06-07

Dissolution of the infinite chain polymer, (OsO(3)F(2))(infinity), in CH(3)CN solvent at -40 degrees C followed by solvent removal under vacuum at -40 degrees C yielded fac-OsO(3)F(2)(NCCH(3)).nCH(3)CN (n >/= 2). Continued pumping at -40 degrees C with removal of uncoordinated CH(3)CN yielded fac-OsO(3)F(2)(NCCH(3)). Both fac-OsO(3)F(2)(NCCH(3)).nCH(3)CN and fac-OsO(3)F(2)(NCCH(3)) are yellow-brown solids and were characterized by low-temperature (-150 degrees C) Raman spectroscopy. The crystal structure (-173 degrees C) of fac-OsO(3)F(2)(NCCH(3)).2CH(3)CN consists of two co-crystallized CH(3)CN molecules and a pseudo-octahedral OsO(3)F(2).NCCH(3) molecule in which three oxygen atoms are in a facial arrangement and CH(3)CN is coordinated trans to an oxygen atom in an end-on fashion. The Os---N bond length (2.205(3) A) is among the shortest M---N adduct bonds observed for a d(0) transition metal oxide fluoride. The (19)F NMR spectrum of (OsO(3)F(2))(infinity) in CH(3)CN solvent (-40 degrees C) is a singlet (-99.6 ppm) corresponding to fac-OsO(3)F(2)(NCCH(3)). The (1)H, (15)N, (13)C, and (19)F NMR spectra of (15)N-enriched OsO(3)F(2)(NCCH(3)) were recorded in SO(2)ClF solvent (-84 degrees C). Nitrogen-15 enrichment resulted in splitting of the (19)F resonance of fac-OsO(3)F(2)((15)NCCH(3)) into a doublet ((2)J((15)N-(19)F), 21 Hz). In addition, a doublet of doublets ((2)J((19)F(ax)-(19)F(eq)), 134 Hz; (2)J((15)N-(19)F(eq)), 18 Hz) and a doublet ((2)J((19)F(ax)-(19)F(eq)), 134 Hz) were observed in the (19)F NMR spectrum that have been assigned to mer-OsO(3)F(2)((15)NCCH(3)); however, coupling of (15)N to the axial fluorine-on-osmium environment could not be resolved. The nitrogen atom of CH(3)CN is coordinated trans to a fluorine ligand in the mer-isomer. Quantum-chemical calculations at the SVWN and B3LYP levels of theory were used to calculate the energy-minimized gas-phase geometries, vibrational frequencies of fac- and mer-OsO(3)F(2)(NCCH(3)) and of CH(3)CN. The relative stabilities of the mer- and fac-isomers have been determined and are in accordance with the solution NMR assignments.

Coupling proton movements to c-ring rotation in F(1)F(o) ATP synthase: aqueous access channels and helix rotations at the a-c interface.

PubMed

Fillingame, Robert H; Angevine, Christine M; Dmitriev, Oleg Y

2002-09-10

F(1)F(o) ATP synthases generate ATP by a rotary catalytic mechanism in which H(+) transport is coupled to rotation of a ring of c subunits within the transmembrane sector of the enzyme. Protons bind to and then are released from the aspartyl-61 residue of subunit c at the center of the membrane. Proton access channels to and from aspartyl-61 are thought to form in subunit a of the F(o) sector. Here, we summarize new information on the structural organization of subunit a and the mapping of aqueous accessible residues in the fourth and fifth transmembrane helices (TMHs). Cysteine substituted residues, lying on opposite faces of aTMH-4, preferentially react with either N-ethyl-maleimide (NEM) or Ag(+). We propose that aTMH-4 rotates to alternately expose each helical face to aspartyl-61 of subunit c during the proton transport cycle. The concerted helical rotation of aTMH-4 and cTMH-2 are proposed to be coupled to the stepwise mechanical movement of the c-rotor.

Ultraviolet-visible optical isolators based on CeF{sub 3} Faraday rotator

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

Víllora, Encarnación G., E-mail: VILLORA.Garcia@nims.go.jp; Shimamura, Kiyoshi; Plaza, Gustavo R.

2015-06-21

The first ultraviolet (UV) and visible optical isolators based on CeF{sub 3} are demonstrated. CeF{sub 3} possesses unique properties as Faraday rotator for the UV-visible wavelength region: a wide transparency range (wavelength of >300 nm) and an outstanding Verdet constant. In contrast, currently used terbium-gallium garnets and magneto-optical glasses possess a low transparency in the visible and a small Verdet constant in the UV, respectively. The optical isolator prototypes consist of a CeF{sub 3} rod, a single ring magnet, and a couple of beam splitters. The ring magnets have been designed to guarantee a homogeneous magnetic field; for it, numerical simulationsmore » have been carried out. The two prototypes are very compact and operate in the UV at 355 and in the visible at 405 nm, respectively. The performance of these devices indicates the high potential of CeF{sub 3} as a new UV-visible Faraday rotator, specially for shorter wavelengths where at present there are no optical isolators available.« less

Structural and optical properties of ZnSe:Eu/ZnS quantum dots depending on interfacial residual europium

NASA Astrophysics Data System (ADS)

Park, Ji Young; Lee, Chan Gi; Seo, Han Wook; Jeong, Da-Woon; Kim, Min Young; Kim, Woo-Byoung; Kim, Bum Sung

2018-01-01

A multimodal emitter comprising of ZnSe:Eu/ZnS (core/shell) quantum dots (QDs) by adding a ZnS precursor in situ during synthesis. ZnSe/Eu2+/Eu3+/ZnS actives both core and core/shell. QDs prepared with the ZnS precursor displayed a luminescence intensity three times that of ZnSe QDs due to the passivation effect of the Shell. While the core QDs display the 450-550 nm emission of Eu2+ (4F65D1 → 4F7), the core/shell system showed no Eu2+ emission but only the sharp peaks in the red at 579, 592, 615, 651, and 700 nm due to the electronic transitions of 5D0 → 7Fn (n = 0-4) depending on leisurely decreased with increased reaction time. These results are in agreement with Eu 3d spectra of XPS analysis results. Microscopic analyses show that the core and core/shell QDs both have a zinc blende structure, and their respective sizes were about 3.19 and 3.44 nm. The lattice constant in the central portion of the core/shell QDs are around d111 = 3.13 Å, which is between the outside and inside ring patterns (d111 = 3.27 and 3.07 Å, respectively). This shows the effective over-capping of shell onto the core QDs. The core/shell structure may contain Eu2O3 bonding the over-coated ZnS surface on the Eu3+-doped ZnSe core.

Investigation of podosome ring protein arrangement using localization microscopy images.

PubMed

Staszowska, Adela D; Fox-Roberts, Patrick; Foxall, Elizabeth; Jones, Gareth E; Cox, Susan

2017-02-15

Podosomes are adhesive structures formed on the plasma membrane abutting the extracellular matrix of macrophages, osteoclasts, and dendritic cells. They consist of an f-actin core and a ring structure composed of integrins and integrin-associated proteins. The podosome ring plays a major role in adhesion to the underlying extracellular matrix, but its detailed structure is poorly understood. Recently, it has become possible to study the nano-scale structure of podosome rings using localization microscopy. Unlike traditional microscopy images, localization microscopy images are reconstructed using discrete points, meaning that standard image analysis methods cannot be applied. Here, we present a pipeline for podosome identification, protein position calculation, and creating a podosome ring model for use with localization microscopy data. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Methyl 4-(4-fluoro­phen­yl)-6-isopropyl-2-[N-methyl-N-(methylsulfonyl)amino]­pyrimidine-5-carboxyl­ate

PubMed Central

He, Wei; Yang, Dong-Ling; Cui, Yong-Tao; Xu, Ye-Ming; Guo, Cheng

2008-01-01

In the mol­ecule of the title compound, C17H20FN3O4S, the pyrimidine and benzene rings are oriented at a dihedral angle of 35.59 (3)°. Intra­molecular C—H⋯N and C—H⋯O hydrogen bonds result in the formation of one five- and two six-membered non-planar rings. One of the six-membered rings adopts a chair conformation, while the other six-membered ring and the five-membered ring exhibit envelope conformations with O and N atoms displaced by 0.837 (3) and 0.152 (3) Å, respectively from the planes of the other ring atoms. In the crystal structure, inter­molecular C—H⋯F hydrogen bonds link the mol­ecules into infinite chains. PMID:21202637

P19-dependent and P19-independent reversion of F1-V gene silencing in tomato.

PubMed

Alvarez, M Lucrecia; Pinyerd, Heidi L; Topal, Emel; Cardineau, Guy A

2008-09-01

As a part of a project to develop a plant-made plague vaccine, we expressed the Yersinia pestis F1-V antigen fusion protein in tomato. We discovered that in some of these plants the expression of the f1-v gene was undetectable in leaves and fruit by ELISA, even though they had multiple copies of f1-v according to Southern-blot analysis. A likely explanation of these results is the phenomenon of RNA silencing, a group of RNA-based processes that produces sequence-specific inhibition of gene expression and may result in transgene silencing in plants. Here we report the reversion of the f1-v gene silencing in transgenic tomato plants through two different mechanisms. In the P19-dependent Reversion or Type I, the viral suppressor of gene silencing, P19, induces the reversion of gene silencing. In the P19-independent Reversion or Type II, the f1-v gene expression is restored after the substantial loss of gene copies as a consequence of transgene segregation in the progeny. The transient and stable expression of the p19 gene driven by a constitutive promoter as well as an ethanol inducible promoter induced a P19-dependent reversion of f1-v gene silencing. In particular, the second generation plant 3D1.6 had the highest P19 protein levels and correlated with the highest F1-V protein accumulation, almost a three-fold increase of F1-V protein levels in fruit than that previously reported for the non-silenced F1-V elite tomato lines. These results confirm the potential exploitation of P19 to substantially increase the expression of value-added proteins in plants.

ALIX and ESCRT-III Coordinately Control Cytokinetic Abscission during Germline Stem Cell Division In Vivo

PubMed Central

Eikenes, Åsmund H.; Malerød, Lene; Christensen, Anette Lie; Steen, Chloé B.; Mathieu, Juliette; Nezis, Ioannis P.; Liestøl, Knut; Huynh, Jean-René; Stenmark, Harald; Haglund, Kaisa

2015-01-01

Abscission is the final step of cytokinesis that involves the cleavage of the intercellular bridge connecting the two daughter cells. Recent studies have given novel insight into the spatiotemporal regulation and molecular mechanisms controlling abscission in cultured yeast and human cells. The mechanisms of abscission in living metazoan tissues are however not well understood. Here we show that ALIX and the ESCRT-III component Shrub are required for completion of abscission during Drosophila female germline stem cell (fGSC) division. Loss of ALIX or Shrub function in fGSCs leads to delayed abscission and the consequent formation of stem cysts in which chains of daughter cells remain interconnected to the fGSC via midbody rings and fusome. We demonstrate that ALIX and Shrub interact and that they co-localize at midbody rings and midbodies during cytokinetic abscission in fGSCs. Mechanistically, we show that the direct interaction between ALIX and Shrub is required to ensure cytokinesis completion with normal kinetics in fGSCs. We conclude that ALIX and ESCRT-III coordinately control abscission in Drosophila fGSCs and that their complex formation is required for accurate abscission timing in GSCs in vivo. PMID:25635693

Synthesis and structure resolution of RbLaF4.

PubMed

Rollet, Anne-Laure; Allix, Mathieu; Veron, Emmanuel; Deschamps, Michael; Montouillout, Valérie; Suchomel, Matthew R; Suard, Emmanuelle; Barre, Maud; Ocaña, Manuel; Sadoc, Aymeric; Boucher, Florent; Bessada, Catherine; Massiot, Dominique; Fayon, Franck

2012-02-20

The synthesis and structure resolution of RbLaF(4) are described. RbLaF(4) is synthesized by solid-state reaction between RbF and LaF(3) at 425 °C under a nonoxidizing atmosphere. Its crystal structure has been resolved by combining neutron and synchrotron powder diffraction data refinements (Pnma,a = 6.46281(2) Å, b = 3.86498(1) Å, c = 16.17629(4) Å, Z = 4). One-dimensional (87)Rb, (139)La, and (19)F MAS NMR spectra have been recorded and are in agreement with the proposed structural model. Assignment of the (19)F resonances is performed on the basis of both (19)F-(139)La J-coupling multiplet patterns observed in a heteronuclear DQ-filtered J-resolved spectrum and (19)F-(87)Rb HMQC MAS experiments. DFT calculations of both the (19)F isotropic chemical shieldings and the (87)Rb, (139)La electric field gradient tensors using the GIPAW and PAW methods implemented in the CASTEP code are in good agreement with the experimental values and support the proposed structural model. Finally, the conductivity of RbLaF(4) and luminescence properties of Eu-doped LaRbF(4) are investigated.

SU-F-J-45: Sparing Normal Tissue with Ultra-High Dose Rate in Radiation Therapy

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

Feng, Y

Purpose: To spare normal tissue by reducing the location uncertainty of a moving target, we proposed an ultra-high dose rate system and evaluated. Methods: High energy electrons generated with a linear accelerator were injected into a storage ring to be accumulated. The number of the electrons in the ring was determined based on the prescribed radiation dose. The dose was delivered within a millisecond, when an online imaging system found that the target was in the position that was consistent with that in a treatment plan. In such a short time period, the displacement of the target was negligible. Themore » margin added to the clinical target volume (CTV) could be reduced that was evaluated by comparing of volumes between CTV and ITV in 14 cases of lung stereotactic body radiation therapy (SBRT) treatments. A design of the ultra-high dose rate system was evaluated based clinical needs and the recent developments of low energy (a few MeV) electron storage ring. Results: This design of ultra-high dose rate system was feasible based on the techniques currently available. The reduction of a target volume was significant by reducing the margin that accounted the motion of the target. ∼50% volume reduction of the internal target volume (ITV) could be achieved in lung SBRT treatments. Conclusion: With this innovation of ultra-high dose rate system, the margin of target is able to be significantly reduced. It will reduce treatment time of gating and allow precisely specified gating window to improve the accuracy of dose delivering.« less

Optimization of 18 F-syntheses using 19 F-reagents at tracer-level concentrations and liquid chromatography/tandem mass spectrometry analysis: Improved synthesis of [18 F]MDL100907.

PubMed

Zhang, Xiang; Dunlow, Ryan; Blackman, Burchelle N; Swenson, Rolf E

2018-05-15

Traditional radiosynthetic optimization faces the challenges of high radiation exposure, cost, and inability to perform serial reactions due to tracer decay. To accelerate tracer development, we have developed a strategy to simulate radioactive 18 F-syntheses by using tracer-level (nanomolar) non-radioactive 19 F-reagents and LC-MS/MS analysis. The methodology was validated with fallypride synthesis under tracer-level 19 F-conditions, which showed reproducible and comparable results with radiosynthesis, and proved the feasibility of this process. Using this approach, the synthesis of [ 18 F]MDL100907 was optimized under 19 F-conditions with greatly improved yield. The best conditions were successfully transferred to radiosynthesis. A radiochemical yield of 19% to 22% was achieved with the radiochemical purity >99% and the molar activity 38.8 to 53.6 GBq/ μmol (n = 3). The tracer-level 19 F-approach provides a high-throughput and cost-effective process to optimize radiosynthesis with reduced radiation exposure. This new method allows medicinal and synthetic chemists to optimize radiolabeling conditions without the need to use radioactivity. Copyright © 2018 John Wiley & Sons, Ltd.

Crystal Structure and Antiferromagnetic Ordering of Quasi-2D [Cu(HF2)(pyz)2]TaF6 (pyz=pyrazine)

NASA Astrophysics Data System (ADS)

Manson, J. L.; Schlueter, J. A.; McDonald, R. D.; Singleton, J.

2010-04-01

The crystal structure of the title compound was determined by X-ray diffraction at 90 and 295 K. Copper(II) ions are coordinated to four bridging pyz ligands to form square layers in the ab-plane. Bridging HF2- ligands join the layers together along the c-axis to afford a tetragonal, three-dimensional (3D) framework that contains TaF6- anions in every cavity. At 295 K, the pyz rings lie exactly perpendicular to the layers and cooling to 90 K induces a canting of those rings. Magnetically, the compound exhibits 2D antiferromagnetic correlations within the 2D layers with an exchange interaction of -13.1(1) K. Weak interlayer interactions, as mediated by Cu-F-H-F-Cu, leads to long-range magnetic order below 4.2 K. Pulsed-field magnetization data at 0.5 K show a concave curvature with increasing B and reveal a saturation magnetization at 35.4 T.

100 km CEPC parameters and lattice design

NASA Astrophysics Data System (ADS)

Wang, D.; Gao, J.; Yu, C. H.; Zhang, Y.; Wang, Y. W.; Su, F.; Y Zhai, J.; Bai, S.; Geng, H. P.; Bian, T. J.; Wang, N.; Cui, X. H.; Zhang, C.; Qin, Q.

2017-07-01

The 100km double ring configuration with shared superconducting RF system has been defined as baseline by the circular electron positron collider (CEPC) steering committee. Based on this new scheme, we will get higher luminosity for Higgs (+170%) keeping the beam power in preliminary conceptual design report (Pre-CDR) or to reduce the beam power (19 MW) while keeping same luminosity. CEPC will be compatible with W and Z experiment. The luminosity for Z is designed at the level of 1035 cm-2s-1. The requirement for the energy acceptance of Higgs has been reduced to 1.5% by enlarging the ring to 100 km. The optics of arc and final focus system (FFS) with crab sextupoles has been designed, and also some primary dynamic aperture (DA) results were introduced. Work supported by the National Key Programme for S&T Research and Development (Grant NO. 2016YFA0400400) and the National Natural Science Foundation of China (11505198, 11575218, 11605210 and 11605211).

19F Magnetic resonance imaging of perfluorooctanoic acid encapsulated in liposome for biodistribution measurement.

PubMed

Kimura, Atsuomi; Narazaki, Michiko; Kanazawa, Yoko; Fujiwara, Hideaki

2004-07-01

The tissue distribution of perfluorooctanoic acid (PFOA), which is known to show unique biological responses, has been visualized in female mice by (19)F magnetic resonance imaging (MRI) incorporated with the recent advances in microimaging technique. The chemical shift selected fast spin-echo method was applied to acquire in vivo (19)F MR images of PFOA. The in vivo T(1) and T(2) relaxation times of PFOA were proven to be extremely short, which were 140 (+/- 20) ms and 6.3 (+/- 2.2) ms, respectively. To acquire the in vivo (19)F MR images of PFOA, it was necessary to optimize the parameters of signal selection and echo train length. The chemical shift selection was effectively performed by using the (19)F NMR signal of CF(3) group of PFOA without the signal overlapping because the chemical shift difference between the CF(3) and neighbor signals reaches to 14 kHz. The most optimal echo train length to obtain (19)F images efficiently was determined so that the maximum echo time (TE) value in the fast spin-echo sequence was comparable to the in vivo T(2) value. By optimizing these parameters, the in vivo (19)F MR image of PFOA was enabled to obtain efficiently in 12 minutes. As a result, the time course of the accumulation of PFOA into the mouse liver was clearly pursued in the (19)F MR images. Thus, it was concluded that the (19)F MRI becomes the effective method toward the future pharmacological and toxicological studies of perfluorocarboxilic acids.

Frequency-Agile Differential Cavity Ring-Down Spectroscopy

NASA Astrophysics Data System (ADS)

Reed, Zachary; Hodges, Joseph

2015-06-01

The ultimate precision of highly sensitive cavity-enhanced spectroscopic measurements is often limited by interferences (etalons) caused by weak coupled-cavity effects. Differential measurements of ring-down decay constants have previously been demonstrated to largely cancel these effects, but the measurement acquisition rates were relatively low [1,2]. We have previously demonstrated the use of frequency agile rapid scanning cavity ring-down spectroscopy (FARS-CRDS) for acquisition of absorption spectra [3]. Here, the method of rapidly scanned, frequency-agile differential cavity ring-down spectroscopy (FADS-CRDS) is presented for reducing the effect of these interferences and other shot-to-shot statistical variations in measured decay times. To this end, an electro-optic phase modulator (EOM) with a bandwidth of 20 GHz is driven by a microwave source, generating pairs of sidebands on the probe laser. The optical resonator acts as a highly selective optical filter to all laser frequencies except for one tunable sideband. This sideband may be stepped arbitrarily from mode-to-mode of the ring-down cavity, at a rate limited only by the cavity buildup/decay time. The ability to probe any cavity mode across the EOM bandwidth enables a variety of methods for generating differential spectra. The differential mode spacing may be changed, and the effect of this method on suppressing the various coupled-cavity interactions present in the system is discussed. Alternatively, each mode may also be differentially referenced to a single point, providing immunity to temporal variations in the base losses of the cavity while allowing for conventional spectral fitting approaches. Differential measurements of absorption are acquired at 3.3 kHz and a minimum detectable absorption coefficient of 5 x10-12 cm-1 in 1 s averaging time is achieved. 1. J. Courtois, K. Bielska, and J.T Hodges J. Opt. Soc. Am. B, 30, 1486-1495, 2013 2. H.F. Huang and K.K. Lehmann App. Optics 49, 1378-1387, 2010 3. G.-W. Truong, K.O. Douglass, S.E. Maxwell, R.D. van Zee, D.F. Plusquellic, J.T. Hodges, and D.A. Long Nature Photonics, 7, 532-534, 2013

Evidence of C-F-P and aromatic π-F-P weak interactions in imidazolium ionic liquids and its consequences

NASA Astrophysics Data System (ADS)

Panja, Sumit Kumar; Srivastava, Nitin; Srivastava, Jyoti; Prasad, Namburi Eswara; Noothalapati, Hemanth; Shigeto, Shinsuke; Saha, Satyen

2018-04-01

A simple change from alkyl group to alkene in side chain of imidazolium cation with same anion resulted in a drastic impact on physical properties (e.g., melting point) from bmimPF6 IL to cmimPF6 IL. The underlying reasons have been elucidated by structural and interaction studies with the help of DSC, SCXRD, vibrational and multi-nuclear NMR spectroscopic techniques. Experiments reveal existence of new weak interactions involving the carbon and π cloud of the imidazolium aromatic ring with fluoride of PF6 anion (i.e., C2-F-P and π-F-P) in cmimPF6 but are absent in structurally similar prototype IL, bmimPF6. Though weak, these interactions helped to form ladder type supramolecular arrangement, resulting in quite high melting point for cmimPF6 IL compared to bmimPF6 IL. These findings emphasize that an IL system can behave uniquely because of the existence of uncommon weak interactions.

Sizes of the Smallest Particles at the Outer B Ring Edge, Huygens Ringlet, and Strange Ringlet

NASA Astrophysics Data System (ADS)

Eckert, Stephanie; Colwell, Josh E.; Becker, Tracy M.; Esposito, Larry W.

2016-10-01

The Cassini Ultraviolet Imaging Spectrograph (UVIS)'s High Speed Photometer (HSP) has observed stellar occultations of Saturn's rings that reveal ring structure at high resolution. We observe diffraction spikes at the sharp edges of some rings and ringlets where the observed signal exceeds the unocculted star signal, indicating that small particles are diffracting light into the detector. Becker et al. (2015 Icarus doi:10.1016/j.icarus.2015.11.001) analyzed data at the A ring edge and edges of the Encke gap. The smallest particle sizes were a few mm. We use the same technique to analyze the diffraction signal at the outer edge of the B ring and the edges of the so-called Strange ringlet near the outer edge of the Huygens Gap. While we see diffraction from sub-cm particles in the Strange Ringlet, detections from the wider Huygens Ringlet which resides in between the Strange Ringlet and the outer edge of the B ring are weaker and narrower, indicating a cutoff of the size distribution above 1 cm. At the outer edge of the B ring we find strong diffraction signals in 7 of 19 occultations for which the signal and geometry make the detection possible. The typical value of the smallest particle size (amin) is 4 mm and the derived slope of the power-law size distribution (q) is 2.9. The average amin is similar to the 4.5 mm average observed at the A ring outer edge while the q value is lower than the A ring outer edge value of 3.2. In the Strange Ringlet we find strong diffraction signals in 2 of 19 possible occultations for the outer edge and 1 of 17 possible occultations for the inner edge. The smallest particle size is ~5 mm and the derived slope of the power-law size distribution is 3.3. These values are similar to the average values at the A ring outer edge. The absence of a broad diffraction signal at the Huygens Ringlet suggests a different size distribution for that ring than for the Strange Ringlet and the outer several km of the B ring or perhaps less vigorous collisions so that fewer small particles are liberated from the regolith of larger particles.

An Analytic Model for the Compression of Plasma Toroids

DTIC Science & Technology

1990-10-01

chamber are only 18 cm apart in the formation section, and the total chamber length can be several meters. The concept is to form a confined plasma ring , and...Focusing of Magnetically Confined Plasma Rings ," Physical Review Letters, Vol. 61, No. 25, pp.2843-2846, 19 December 1988. 2. Turner, W. C., Goldenbaum, G

Development of 19F-NMR chemical shift detection of DNA B-Z equilibrium using 19F-NMR.

PubMed

Nakamura, S; Yang, H; Hirata, C; Kersaudy, F; Fujimoto, K

2017-06-28

Various DNA conformational changes are in correlation with biological events. In particular, DNA B-Z equilibrium showed a high correlation with translation and transcription. In this study, we developed a DNA probe containing 5-trifluoromethylcytidine or 5-trifluoromethylthymidine to detect DNA B-Z equilibrium using 19 F-NMR. Its probe enabled the quantitative detection of B-, Z-, and ss-DNA based on 19 F-NMR chemical shift change.

Polarized 3-folds in a codimension 10 weighted homogeneous F4 variety

NASA Astrophysics Data System (ADS)

Qureshi, Muhammad Imran

2017-10-01

We describe the construction of a codimension 10 weighted homogeneous variety wΣF4(μ , u) corresponding to the exceptional Lie group F4 by explicit computation of its graded ring structure. We give a formula for the Hilbert series of the generic weighted wΣF4(μ , u) in terms of representation theoretic data of F4. We also construct some families of polarized 3-folds in codimension 10 whose general member is a weighted complete intersection of some wΣF4(μ , u) .

Thermodynamic properties of ternary oxides in the system Ba-Fe-O using solid-state electrochemical cells with oxide and fluoride ion conducting electrolytes

NASA Astrophysics Data System (ADS)

Rakshit, S. K.; Parida, S. C.; Singh, Ziley; Prasad, R.; Venugopal, V.

2004-04-01

The standard molar Gibbs energy of formations of BaFe 12O 19(s), BaFe 2O 4(s), Ba 2Fe 2O 5(s), Ba 3Fe 2O 6(s) and Ba 5Fe 2O 8(s) have been determined using solid-state electrochemical technique employing CaF 2(s) as an electrolyte. The reversible e.m.f. values have been measured in the temperature range from 970 to 1151 K. The oxygen chemical potential corresponding to three phase equilibria involving technologically important compound BaFe 12O 19(s) has been determined using solid-state electrochemical technique employing CSZ as an electrolyte from 1048 to 1221 K. The values of Δ fGm0( T) for the above ternary oxides are given by ΔfG m0( BaFe12O19, s)/ kJ mol -1(±0.6)=-5431.3+1.5317 (T/ K) (970⩽T/ K⩽1151) ΔfG m0( BaFe2O4, s)/ kJ mol -1(±1.3)=-1461.4+0.3745 (T/ K) (970⩽T/ K⩽1151) ΔfG m0( Ba2Fe2O5, s)/ kJ mol -1(±1.4)=-2038.3+0.4433 (T/ K) (970⩽T/ K⩽1149) ΔfG m0( Ba3Fe2O6, s)/ kJ mol -1(±1.5)=-2700.1+0.6090 (T/ K) (969⩽T/ K⩽1150) and ΔfG m0( Ba5Fe2O8, s)/ kJ mol -1(±1.6)=-3984.1+0.9300 (T/ K) (973⩽T/ K⩽1150) The uncertainty estimates for Δ fGm0 includes the standard deviation in the e.m.f. and uncertainty in the data taken from the literature. An isothermal oxygen potential diagram for the system Ba-Fe-O was constructed at 1100 K based on the thermodynamic data obtained in this study.

Direct mapping of 19F in 19FDG-6P in brain tissue at subcellular resolution using soft X-ray fluorescence

NASA Astrophysics Data System (ADS)

Poitry-Yamate, C.; Gianoncelli, A.; Kourousias, G.; Kaulich, B.; Lepore, M.; Gruetter, R.; Kiskinova, M.

2013-10-01

Low energy x-ray fluorescence (LEXRF) detection was optimized for imaging cerebral glucose metabolism by mapping the fluorine LEXRF signal of 19F in 19FDG, trapped as intracellular 19F-deoxyglucose-6-phosphate (19FDG-6P) at 1μm spatial resolution from 3μm thick brain slices. 19FDG metabolism was evaluated in brain structures closely resembling the general cerebral cytoarchitecture following formalin fixation of brain slices and their inclusion in an epon matrix. 2-dimensional distribution maps of 19FDG-6P were placed in a cytoarchitectural and morphological context by simultaneous LEXRF mapping of N and O, and scanning transmission x-ray (STXM) imaging. A disproportionately high uptake and metabolism of glucose was found in neuropil relative to intracellular domains of the cell body of hypothalamic neurons, showing directly that neurons, like glial cells, also metabolize glucose. As 19F-deoxyglucose-6P is structurally identical to 18F-deoxyglucose-6P, LEXRF of subcellular 19F provides a link to in vivo 18FDG PET, forming a novel basis for understanding the physiological mechanisms underlying the 18FDG PET image, and the contribution of neurons and glia to the PET signal.

Weak hydrogen bonding and fluorous interactions in the chloride and bromide salts of 4-[(2,2,3,3-tetrafluoropropoxy)methyl]pyridinium.

PubMed

Lu, Norman; Wei, Rong Jyun; Lin, Kwan Yu; Alagesan, Mani; Wen, Yuh Sheng; Liu, Ling Kang

2017-04-01

Neutralization of 4-[(2,2,3,3-tetrafluoropropoxy)methyl]pyridine with hydrohalo acids HX (X = Cl and Br) yielded the pyridinium salts 4-[(2,2,3,3-tetrafluoropropoxy)methyl]pyridinium chloride, C 9 H 10 F 4 NO + ·Cl - , (1), and 4-[(2,2,3,3-tetrafluoropropoxy)methyl]pyridinium bromide, C 9 H 10 F 4 NO + ·Br - , (2), both carrying a fluorous side chain at the para position of the pyridinium ring. Single-crystal X-ray diffraction techniques revealed that (1) and (2) are isomorphous. The halide anions accept four hydrogen bonds from N-H, ortho-C-H and CF 2 -H groups. Two cations and two anions form a centrosymmetric dimeric building block, utilizing complimentary N-H...X...H-Csp 3 connections. These dimers are further crosslinked, utilizing another complimentary Csp 2 -H...X...H-Csp 2 connection. The pyridinium rings are π-stacked, forming columns running parallel to the a axis that make angles of ca 44-45° with the normal to the pyridinium plane. There are also supramolecular C-H...F-C interactions, namely bifurcated C-H...F and bifurcated C-F...H interactions; additionally, one type II C-F...F-C halogen bond has been observed.

Low Temperature Fluorination of Aerosol and Condensed Phase Sol Suspensions of Hydrocarbons Utilizing Elemental Fluorine.

DTIC Science & Technology

1980-04-01

subambient temperature capability of our design . The aerosol fluorination system designed to produce a controlled , con- tinuous stream of aerosol...F3 H8 , 117 (68.9) C6F2H7 CN: D I Mixture CO: D I’’ Difluorocyclohexane Isomer (two nonequivalent CFR groups ) 1 H NMR no integration given 1 9F NMR: d...two nonequivalent CFH groups ) 1H NMR no integration given 19F NMR d? at 193.5 ppm (J = 106.8 Rz ?) 32 TABLE 7 (CONTINUED) MS: CI: 119 (1.4) C6F2

Design principles and theory of paramagnetic fluorine-labelled lanthanide complexes as probes for (19)F magnetic resonance: a proof-of-concept study.

PubMed

Chalmers, Kirsten H; De Luca, Elena; Hogg, Naomi H M; Kenwright, Alan M; Kuprov, Ilya; Parker, David; Botta, Mauro; Wilson, J Ian; Blamire, Andrew M

2010-01-04

The synthesis and spectroscopic properties of a series of CF(3)-labelled lanthanide(III) complexes (Ln=Gd, Tb, Dy, Ho, Er, Tm) with amide-substituted ligands based on 1,4,7,10-tetraazacyclododecane are described. The theoretical contributions of the (19)F magnetic relaxation processes in these systems are critically assessed and selected volumetric plots are presented. These plots allow an accurate estimation of the increase in the rates of longitudinal and transverse relaxation as a function of the distance between the Ln(III) ion and the fluorine nucleus, the applied magnetic field, and the re-rotational correlation time of the complex, for a given Ln(III) ion. Selected complexes exhibit pH-dependent chemical shift behaviour, and a pK(a) of 7.0 was determined in one example based on the holmium complex of an ortho-cyano DO3A-monoamide ligand, which allowed the pH to be assessed by measuring the difference in chemical shift (varying by over 14 ppm) between two (19)F resonances. Relaxation analyses of variable-temperature and variable-field (19)F, (17)O and (1)H NMR spectroscopy experiments are reported, aided by identification of salient low-energy conformers by using density functional theory. The study of fluorine relaxation rates, over a field range of 4.7 to 16.5 T allowed precise computation of the distance between the Ln(III) ion and the CF(3) reporter group by using global fitting methods. The sensitivity benefits of using such paramagnetic fluorinated probes in (19)F NMR spectroscopic studies are quantified in preliminary spectroscopic and imaging experiments with respect to a diamagnetic yttrium(III) analogue.

Critical Problems in Very Large Scale Computer Systems

DTIC Science & Technology

1990-03-31

Srinivas Devadas (617) 253-0454 Thomas F. Knight, Jr. (617) 253-7807 F. Thomson Leighton (617) 253-3662 Charles E. Leiserson (617) 253-5833 Jacob K...Aided Design of Integrated Circuits and Systems, pages 19-29, January 1990. [5] S. Arora, T. Leighton, and B . Maggs. On-line algorithms for path...selection in a non-blocking network. In Proceedings of the 21st Annual ACM Symposium on Theory of Computing, May 1990. To appear. [6] P. Ashar, S. Devadas

Fatigue behaviour of core-spun yarns containing filament by means of cyclic dynamic loading

NASA Astrophysics Data System (ADS)

Esin, S.; Osman, B.

2017-10-01

The behaviour of yarns under dynamic loading is important that leads to understand the growth characteristics which is exposed to repetitive loadings during usage of fabric made from these yarns. Fabric growth is undesirable property that originated from low resilience characteristics of fabric. In this study, the effects of the filament fineness and yarn linear density on fatigue behaviour of rigid-core spun yarns were determined. Cotton covered yarns containing different filament fineness of polyester (PET) draw textured yarns (DTY) (100d/36f, 100d/96f, 100d/144f, 100d/192f and 100d/333f) and yarn linear densities (37 tex, 30 tex, 25 tex and 21 tex) were manufactured by using a modified ring spinning system at the same spinning parameters. Repetitive loads were applied for 25 cycles at levels between 0.1 and 3 N. Dynamic modulus and dynamic strain of yarn samples were analyzed statistically. Results showed that filament fineness and yarn linear density have significance effect on dynamic modulus and dynamic strain after cyclic loading.

Rapid quantification of inflammation in tissue samples using perfluorocarbon emulsion and fluorine-19 nuclear magnetic resonance

PubMed Central

Ahrens, Eric T.; Young, Won-Bin; Xu, Hongyan; Pusateri, Lisa K.

2016-01-01

Quantification of inflammation in tissue samples can be a time-intensive bottleneck in therapeutic discovery and preclinical endeavors. We describe a versatile and rapid approach to quantitatively assay macrophage burden in intact tissue samples. Perfluorocarbon (PFC) emulsion is injected intravenously, and the emulsion droplets are effectively taken up by monocytes and macrophages. These ‘in situ’ labeled cells participate in inflammatory events in vivo resulting in PFC accumulation at inflammatory loci. Necropsied tissues or intact organs are subjected to conventional fluorine-19 (19F) NMR spectroscopy to quantify the total fluorine content per sample, proportional to the macrophage burden. We applied these methods to a rat model of experimental allergic encephalomyelitis (EAE) exhibiting extensive inflammation and demyelination in the central nervous system (CNS), particularly in the spinal cord. In a cohort of EAE rats, we used 19F NMR to derive an inflammation index (IFI) in intact CNS tissues. Immunohistochemistry was used to confirm intracellular colocalization of the PFC droplets within CNS CD68+ cells having macrophage morphology. The IFI linearly correlated to mRNA levels of CD68 via real-time PCR analysis. This 19F NMR approach can accelerate tissue analysis by at least an order of magnitude compared with histological approaches. PMID:21548906

Mechanistic insight into formation and changes of nanoparticles in MgF2 sols evidenced by liquid and solid state NMR.

PubMed

Karg, M; Scholz, G; König, R; Kemnitz, E

2012-02-28

The fluorolytic sol-gel reaction of magnesium methoxide with HF in methanol was studied by (19)F, (1)H and (13)C liquid and solid state NMR. In (19)F NMR five different species were identified, three of which belong to magnesium fluoride nanoparticles, i.e. NMR gave access to local structures of solid particles in suspensions. The long-term evolution of (19)F signals was followed and along with (19)F MAS NMR experiments of sols rotating at 13 kHz mechanistic insights into the ageing processes were obtained.

Atmospheric-pressure plasma jet system for silicon etching without fluorocarbon gas feed

NASA Astrophysics Data System (ADS)

Ohtsu, Yasunori; Nagamatsu, Kenta

2018-01-01

We developed an atmospheric-pressure plasma jet (APPJ) system with a tungsten rod electrode coated with C2F4 particles of approximately 0.3 µm diameter for the surface treatment of a silicon wafer. The APPJ was generated by dielectric barrier discharge with a driving frequency of 22 kHz using a He gas flow. The characteristics of the APPJ were examined under various experimental conditions. The plasma jet length increased proportionally to the electric field. It was found that the treatment area of the silicon wafer was approximately 1 mm in diameter. By atomic force microscopy analysis, minute irregularities with a maximum length of about 600 nm and part of a ring-shaped trench were observed. A Si etching rate of approximately 400 nm/min was attained at a low power of 6 W and a He flow rate of 1 L/min without introducing molecular gas including F atoms.

Expression of galectin-3, cytokeratin 19, neural cell adhesion molecule and E-cadhedrin in certain variants of papillary thyroid carcinoma.

PubMed

Laco, J; Ryska, A; Cáp, J; Celakovský, P

2008-10-01

The immunohistochemical expression of galectin-3 (Gal3), cytokeratin 19 (CK19), neural cell adhesion molecule (NCAM), and E-cadherin (Ecad) was evaluated to assess their use in diagnostics of papillary thyroid carcinoma (PTC). A total of 84 PTCs - 36 classical variants (cPTCs), 26 follicular variants (fPTCs), and 22 papillary microcarcinomas (mPTCs) were studied. Expression of Gal3 was found in 36/36 (100%) cPTCs, 24/26 (92%) fPTCs, and 19/22 (86%) mPTCs. CK19 expression was detected in 34/36 (94%) cPTCs, 17/26 (65%) fPTCs, and 13/22 (59%) mPTCs. Expression of NCAM was seen in 5/36 (14%) cPTCs, 7/26 (27%) fPTCs, and 9/22 (41%) mPTCs. Ecad expression was found in 23/36 (64%) cPTCs, 17/26 (65%) fPTCs, and 18/22 (82%) mPTCs. A significant difference in CK19 expression was observed between cPTC and both fPTC and mPTC (p < 0.001). Furthermore, extrathyroid tumor spread significantly correlated with both level of CK19 expression and loss of Ecad expression (p = 0.001, p = 0.04). Our findings suggest that Gal3 and CK19 are useful markers for PTC, although decreased CK19 expression in mPTC and fPTC must be considered. Furthermore, CK19 and Ecad may play a role in extrathyroid tumor spread.

1-[(6-Chloro-3-pyrid­yl)meth­yl]-5-eth­oxy-8-nitro-1,2,3,5,6,7-hexa­hydro­imidazo[1,2-a]pyridine

PubMed Central

Tian, Zhongzhen; Li, Dongmei; Li, Zhong

2009-01-01

In the title compound, C15H19ClN4O3, an active agrochemical possessing insecticidal activity, the dihedral angle between the mean planes passing through the pyridine ring and the five-membered ring is 87.3 (2)°. The fused pyridine ring adopts a twisted sofa conformation. The mol­ecular structure features close intra­molecular C—H⋯N and C—H⋯O hydrogen bonding. PMID:21577964

Crystal structure of 3-({[(morpholin-4-yl)carbono-thio-yl]sulfan-yl}acet-yl)phenyl benzoate.

PubMed

Ambekar, Sachin P; Mahesh Kumar, K; Shirahatti, Arun Kumar M; Kotresh, O; Anil Kumar, G N

2014-11-01

In the title compound, C20H19NO4S2, the morpholine ring adopts the expected chair conformation. The central phenyl ring makes dihedral angles of 67.97 (4) and 7.74 (3)°, respectively, with the benzoate phenyl ring and the morpholine mean plane. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming zigzag chains along the b-axis direction. C-H⋯π inter-actions link centrosymmetrically related mol-ecules, reinforcing the three-dimensional structure.

Cassini/MIMI Science Today and Tomorrow

NASA Astrophysics Data System (ADS)

Mitchell, D. G.

2014-12-01

Between Saturn Orbit Insertion in July 2004 and the present, the Magnetospheric IMaging Instrument (MIMI) on the Cassini spacecraft has measured electrons and ions (energies ~5 keV to over 10 MeV and energetic neutrals (energies ~5 - 200 keV) throughout Saturn's magnetosphere including Saturn's bow shock and magnetopause, plasma sheet, magnetotail, and cis-moon spaces. MIMI observations have included auroral acceleration, magnetotail reconnection, global and local-scale injection events, identifications of charged particle species,, dual and multiple periodicities associated with planetary rotation, and the seasonal variations of many of these phenomena. Most recent MIMI investigations have shown (1) short-period charged-particle oscillations (~1 hour) at high latitude are associated with similar magnetic field, radio, and aurora variations (2) quasi-periodic relativistic electron injection in Saturn's outer magnetosphere, (3) modeling of radiation belt particles to explain their distribution and energy spectrum, and to anticipate the population inside the D-ring, (4) continuing the imaging of energetic neutral atoms (ENAs) from the heliosheath and beyond, (5) characterizing the interaction of Titan with the un-shocked solar wind, (6) deep tail observations supporting the "bowl model" of plasma sheet curvature, (7) asymmetries in the charged particles that are associated with a still-unexplained noon-midnight electric field, (8) local time variations in the energetic particle periodicities, (9) and signatures of satellite-magnetosphere interactions and their implications for both the body and the whole system. During the final sets of orbits of the Cassini Mission at Saturn (dubbed the Grand Finale, which includes the F-ring—periapsis outside the F-ring—and the Proximal Orbits—periapsis between the innermost D-ring and the atmosphere), MIMI will make the first-ever measurements of the innermost radiation belts of Saturn, detailed ENA imaging of charged particle acceleration above the high-latitude polar caps, composition of any energetic plasma between the rings and the ionosphere, and evidence for coupling between the rings, ionosphere, and magnetosphere.

Parametric Analysis of Energy Consumption in Army Buildings by the Building Loads Analysis and System Thermodynamics (BLAST) Computer Program.

DTIC Science & Technology

1980-08-01

orientation, and HVAC systems have on three Army buildings in five different climatic regions. f Optimization of EnerV Usage in Military Facilities...The clinic’s environment is maintained by a multizone air-handling unit served by its own boiler and chiller . The building was modeled with 30... setpoints for the space temperature. This type of throttling range allows the heating system to control around a throttling range of 67 to 69oF (19 to 200

The role of tidal torques on the evolution of the system of Saturn's co-orbital satellites Janus and Epimetheus

NASA Astrophysics Data System (ADS)

Caudal, Gérard V.

2013-04-01

This paper discusses the effect of tides raised by Saturn on its co-orbital satellites Janus and Epimetheus, and its consequences on the long-term evolution of the co-orbital horseshoe pattern of those moons. This tidal effect is found to produce a loosening of the co-orbital lock of Janus and Epimetheus. The increase of the difference D between their semi-major axes under this process is estimated as 2.77 km/Myear, regardless of whether the moons are composed of monolithic or fractured ice. On the other hand, assuming that the outer edge of Saturn's A ring is permanently maintained by Janus and Epimetheus at their 7:6 resonance, Lissauer et al. [Lissauer, J.J., Goldreich, P., Tremaine S., 1985. Icarus 64, 425-434] have shown that the torques exerted on Janus and Epimetheus due to resonances with Saturn's rings would produce a tightening of the co-orbital lock. The rate of decrease of orbital difference D under that latter process depends upon the precise relative radial location of the A-ring outer edge as compared with Janus' lower orbit semi-major axis, which is quantified here by means of a parameter po characterizing the efficiency of the effect of Janus' ring resonance. Under the combined effects of those two processes, depending on the value of po relative to a critical value po ≈ 19%, the system will evolve toward either a transition from horseshoe to tadpole orbit, or to a destruction of the co-orbital lock, after a few tens of Myears. Most recent observations of the A ring's outer edge by Spitale and Porco [Spitale, J.N., Porco, C.C., 2009. The Astronomical Journal 138, 1520-1528] tend to indicate that the future evolution will be a net tightening of the co-orbital system, until a tadpole situation will be reached after about 15 Myears. From a study of the past history of the co-orbital system, it is shown that such a scenario is compatible with a capture from free orbits to co-orbital horseshoe pattern some 25 Myears ago.

Two dynamin-like proteins stabilize FtsZ rings during Streptomyces sporulation.

PubMed

Schlimpert, Susan; Wasserstrom, Sebastian; Chandra, Govind; Bibb, Maureen J; Findlay, Kim C; Flärdh, Klas; Buttner, Mark J

2017-07-25

During sporulation, the filamentous bacteria Streptomyces undergo a massive cell division event in which the synthesis of ladders of sporulation septa convert multigenomic hyphae into chains of unigenomic spores. This process requires cytokinetic Z-rings formed by the bacterial tubulin homolog FtsZ, and the stabilization of the newly formed Z-rings is crucial for completion of septum synthesis. Here we show that two dynamin-like proteins, DynA and DynB, play critical roles in this process. Dynamins are a family of large, multidomain GTPases involved in key cellular processes in eukaryotes, including vesicle trafficking and organelle division. Many bacterial genomes encode dynamin-like proteins, but the biological function of these proteins has remained largely enigmatic. Using a cell biological approach, we show that the two Streptomyces dynamins specifically localize to sporulation septa in an FtsZ-dependent manner. Moreover, dynamin mutants have a cell division defect due to the decreased stability of sporulation-specific Z-rings, as demonstrated by kymographs derived from time-lapse images of FtsZ ladder formation. This defect causes the premature disassembly of individual Z-rings, leading to the frequent abortion of septum synthesis, which in turn results in the production of long spore-like compartments with multiple chromosomes. Two-hybrid analysis revealed that the dynamins are part of the cell division machinery and that they mediate their effects on Z-ring stability during developmentally controlled cell division via a network of protein-protein interactions involving DynA, DynB, FtsZ, SepF, SepF2, and the FtsZ-positioning protein SsgB.

Actin grips: circular actin-rich cytoskeletal structures that mediate the wrapping of polymeric microfibers by endothelial cells.

PubMed

Jones, Desiree; Park, DoYoung; Anghelina, Mirela; Pécot, Thierry; Machiraju, Raghu; Xue, Ruipeng; Lannutti, John J; Thomas, Jessica; Cole, Sara L; Moldovan, Leni; Moldovan, Nicanor I

2015-06-01

Interaction of endothelial-lineage cells with three-dimensional substrates was much less studied than that with flat culture surfaces. We investigated the in vitro attachment of both mature endothelial cells (ECs) and of less differentiated EC colony-forming cells to poly-ε-capro-lactone (PCL) fibers with diameters in 5-20 μm range ('scaffold microfibers', SMFs). We found that notwithstanding the poor intrinsic adhesiveness to PCL, both cell types completely wrapped the SMFs after long-term cultivation, thus attaining a cylindrical morphology. In this system, both EC types grew vigorously for more than a week and became increasingly more differentiated, as shown by multiplexed gene expression. Three-dimensional reconstructions from multiphoton confocal microscopy images using custom software showed that the filamentous (F) actin bundles took a conspicuous ring-like organization around the SMFs. Unlike the classical F-actin-containing stress fibers, these rings were not associated with either focal adhesions or intermediate filaments. We also demonstrated that plasma membrane boundaries adjacent to these circular cytoskeletal structures were tightly yet dynamically apposed to the SMFs, for which reason we suggest to call them 'actin grips'. In conclusion, we describe a particular form of F-actin assembly with relevance for cytoskeletal organization in response to biomaterials, for endothelial-specific cell behavior in vitro and in vivo, and for tissue engineering. Copyright © 2015 Elsevier Ltd. All rights reserved.

New insights about the structure and variability of Saturn's electron radiation belts from Cassini's Ring-Grazing and Proximal orbits

NASA Astrophysics Data System (ADS)

Roussos, E.; Kollmann, P.; Krupp, N.; Paranicas, C.; Dialynas, K.; Sergis, N.; Mitchell, D. G.; Krimigis, S. M.

2017-12-01

During 2008, Cassini performed a unique series of orbits with a period of about 7 days which allowed us to monitor the evolution of Saturn's radiation belts across time scales shorter than the 28-day solar rotation and to identify the role of Corotating Interaction Regions (CIRs) as a key driver of dynamics for the belts' MeV electron population. Cassini's "Grand Finale" included a new set of such short-period orbits (6.5 to 7.2 days long), executed continuously between November 20, 2016 until September 15, 2017. While the 2008 observations were typically limited up to the L-shell of the G-ring, the Grand Finale orbits probed the radiation belts deeper and for a longer duration, covering the sparsely sampled regions outside the F- and A-rings and the previously unexplored particle trapping region inside the main rings. Observations with Cassini's MIMI/LEMMS instrument reveal that the electron belt intensities are persistently asymmetric in local time all the way down to the exterior edge of the main rings. The strength of this asymmetry appears to correlate with the appearence of transient belt components and changes in the intensity of the main belts which may be triggered by solar-wind or magnetospheric driven storms. The intensity of transient components in the electron belts, that may also appear in the small gap between the A- and the F-rings, evolve over several weeks, indicating that convection may occasionally dominate diffusive electron transport, the time scales of which are longer. Detection of MeV electrons inside the main rings during the Proximal orbits is ambiguous, but if electrons are present, all the LEMMS channels that may contain their signal indicate that their distribution would be very stable in time and unaffected by convective fields that drive electron transport outside the main rings.

Conformation analysis and molecular mobility of ethylene and tetrafluoroethylene copolymer using solid-state 19F MAS and 1H --> 19F CP/MAS NMR spectroscopy.

PubMed

Aimi, Keitaro; Ando, Shinji

2004-07-01

The changes in the conformation and molecular mobility accompanied by a phase transition in the crystalline domain were analyzed for ethylene (E) and tetrafluoroethylene (TFE) copolymer, ETFE, using variable-temperature (VT) solid-state 19F magic angle spinning (MAS) and 1H --> 19F cross-polarization (CP)/MAS NMR spectroscopy. The shifts of the signals for fluorines in TFE units to higher frequency and the continuing decrease and increase in the T1rho(F) values suggest that conformational exchange motions exist in the crystalline domain between 42 and 145 degrees C. Quantum chemical calculations of magnetic shielding constants showed that the high-frequency shift of TFE units should be induced by trans to gauche conformational changes at the CH2-CF2 linkage in the E-TFE unit. Although the 19F signals of the crystalline domain are substantially overlapped with those of the amorphous domain at ambient probe temperature (68 degrees C), they were successfully distinguished by using the dipolar filter and spin-lock pulse sequences at 145 degrees C. The dipolar coupling constants for the crystalline domain, which can be estimated by fitting the dipolar oscillation behaviors in the 1H --> 19F CP curve, showed a significant decrease with increasing temperature from 42 to 145 degrees C. This is due to the averaging of 1H-19F dipolar interactions originating from the molecular motion in the crystalline domain. The increase in molecular mobility in the crystalline domain was clearly shown by VT T1rho(F) and 1H --> 19F CP measurements in the phase transition temperature range. Copyright 2004 John Wiley & Sons, Ltd.

In Vivo Cytometry of Antigen-Specific T Cells Using 19F MRI

PubMed Central

Srinivas, Mangala; Turner, Michael S.; Janjic, Jelena M.; Morel, Penelope A.; Laidlaw, David H.; Ahrens, Eric T.

2009-01-01

Noninvasive methods to image the trafficking of phenotypically defined immune cells are paramount as we attempt to understand adaptive immunity. A 19F MRI-based methodology for tracking and quantifying cells of a defined phenotype is presented. These methods were applied to a murine inflammation model using antigen-specific T cells. The T cells that were intracellularly labeled ex vivo with a perfluoropolyether (PFPE) nanoemulsion and cells were transferred to a host receiving a localized inoculation of antigen. Longitudinal 19F MRI over 21 days revealed a dynamic accumulation and clearance of T cells in the lymph node (LN) draining the antigen. The apparent T-cell numbers were calculated in the LN from the time-lapse 19F MRI data. The effect of in vivo T-cell division on the 19F MRI cell quantification accuracy was investigated using fluorescence assays. Overall, in vivo cytometry using PFPE labeling and 19F MRI is broadly applicable to studies of whole-body cell biodistribution. PMID:19585593

Gadolinium-modulated 19F signals from Perfluorocarbon Nanoparticles as a New Strategy for Molecular Imaging

PubMed Central

Neubauer, Anne M.; Myerson, Jacob; Caruthers, Shelton D.; Hockett, Franklin D.; Winter, Patrick M.; Chen, Junjie; Gaffney, Patrick J.; Robertson, J. David; Lanza, Gregory M.; Wickline, Samuel A.

2008-01-01

Recent advances in the design of fluorinated nanoparticles for magnetic resonance molecular imaging have enabled specific detection of 19F nuclei, providing unique and quantifiable spectral signatures. However, a pressing need for signal enhancement exists because the total 19F in imaging voxels is often limited. By directly incorporating a relaxation agent (gadolinium) into the lipid monolayer that surrounds the perfluorocarbon, a marked augmentation of the 19F signal from 200nm nanoparticles was achieved. This design increases the magnetic relaxation rate of the 19F nuclei 4-fold at 1.5 T and effects a 125% increase in signal, an effect which is maintained when they are targeted to human plasma clots. By varying the surface concentration of gadolinium, the relaxation effect can be quantitatively modulated to tailor particle properties. This novel strategy dramatically improves the sensitivity and range of 19F MRI/MRS and forms the basis for designing contrast agents capable of sensing their surface chemistry. PMID:18956457

Micro-ring sensor used in the diagnosis of gastric cancer

NASA Astrophysics Data System (ADS)

Shi, Sichao; Cheng, Qing; Lin, Rong; Su, Da; Huang, Ying

2016-01-01

To find a detecting method that can be applied to the clinical screening and diagnosis, the cascaded micro-ring sensor with Vernier effect was used to distinguish gastric cancerous and normal cells. The simulation by FDTD of the cascaded microring sensor with different refractive indexes of the analyte (normal cells and gastric cancer cells) will be presented. In the simulation, with the refractive index's change Δn=0.02 for the two different analyte, the shift of sensor's resonant wavelength is 6.71nm. And the cascaded micro-ring sensor's sensitivity S is 335.5nm/RIU, and it is much larger compared to 19nm/RIU for a single ring sensor.

Application of dual 19 F and iron cellular MRI agents to track the infiltration of immune cells to the site of a rejected stem cell transplant.

PubMed

Gaudet, Jeffrey M; Hamilton, Amanda M; Chen, Yuanxin; Fox, Matthew S; Foster, Paula J

2017-08-01

Cellular MRI) was used to detect implanted human mesenchymal stem cells (hMSCs) and the resulting macrophage infiltration that occurs in response to xenotransplantation. Human mesenchymal stem cells were prelabeled with a fluorine-19 ( 19 F) agent prior to implantation, allowing for their visualization and quantification over time. Following implantation of 1 × 10 6 19 F-labeled hMSCs into the mouse hind limb, longitudinal imaging was performed to monitor the stem cell graft. Macrophages were labeled in situ by the intravenous administration of an ultrasmall superparamagentic iron oxide (USPIO), allowing for tracking of the inflammatory response. Quantification of 19 F MRI on day 0 agreed with the implanted number of cells, and 19 F signal decreased over time. By day 14, only 22% ± 11% of the original 19 F signal remained. In a second group, USPIO were administered intravenously after implantation of 19 F-labeled hMSCs. When imaged on day 2, a significant decrease in 19 F signal was observed compared to the first group alongside a large signal void region in the corresponding proton images. Immunohistochemistry confirmed the presence of iron-labeled macrophages in the stem cell tract. A dual-labeling technique was used to noninvasively track two distinct cell populations simultaneously. This information could be used to provide additional insight into the cause of graft failure. Magn Reson Med 78:713-720, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

A generalized strategy for designing (19)F/(1)H dual-frequency MRI coil for small animal imaging at 4.7 Tesla.

PubMed

Hu, Lingzhi; Hockett, Frank D; Chen, Junjie; Zhang, Lei; Caruthers, Shelton D; Lanza, Gregory M; Wickline, Samuel A

2011-07-01

To propose and test a universal strategy for building (19) F/(1) H dual-frequency RF coil that permits multiple coil geometries. The feasibility to design (19) F/(1) H dual-frequency RF coil based on coupled resonator model was investigated. A series capacitive matching network enables robust impedance matching for both harmonic oscillating modes of the coupled resonator. Two typical designs of (19) F/(1) H volume coils (birdcage and saddle) at 4.7T were implemented and evaluated with electrical bench test and in vivo (19) F/(1) H dual-nuclei imaging. For various combinations of internal resistances of the sample coil and secondary resonator, numerical solutions for the tunable capacitors to optimize impedance matching were obtained using a root-seeking program. Identical and homogeneous B1 field distribution at (19) F and (1) H frequencies were observed in bench test and phantom image. Finally, in vivo mouse imaging confirmed the sensitivity and homogeneity of the (19) F/(1) H dual-frequency coil design. A generalized strategy for designing (19) F/(1) H dual-frequency coils based on the coupled resonator approach was developed and validated. A unique feature of this design is that it preserves the B1 field homogeneity of the RF coil at both resonant frequencies. Thus it minimizes the susceptibility effect on image co-registration. Copyright © 2011 Wiley-Liss, Inc.

Diffusional mechanisms augment the fluorine magnetic resonance relaxation in paramagnetic perfluorocarbon nanoparticles that provides a “relaxation switch” for detecting cellular endosomal activation

PubMed Central

Hu, Lingzhi; Zhang, Lei; Chen, Junjie; Lanza, Gregory M.; Wickline, Samuel A.

2011-01-01

Purpose To develop a physical model for the 19F relaxation enhancement in paramagnetic perfluorocarbon nanoparticles (PFC NP) and demonstrate its application in monitoring cellular endosomal functionality through a “19F relaxation switch” phenomenon. Materials and Methods An explicit expression for 19F longitudinal relaxation enhancement was derived analytically. Monte-Carlo simulation was performed to confirm the gadolinium induced magnetic field inhomogenity inside the PFC NP. Field dependent T1 measurements for three types of paramagnetic PFC NPs were carried out to validate the theoretical prediction. Based on the physical model, 19F and 1H relaxation properties of macrophage internalized paramagnetic PFC NPs were measured to evaluate the intracellular process of NPs by macrophages in vitro. Results The theoretical description was confirmed experimentally by field-dependent T1 measurements. The shortening of 19F T1 was found to be attributed to the Brownian motion of PFC molecules inside the NP in conjunction with their ability to permeate into the lipid surfactant coating. A dramatic change of 19F T1 was observed upon endocytosis, revealing the transition from intact bound PFC NP to processed constituents. Conclusion The proposed first-principle analysis of 19F spins in paramagnetic PFC NP relates their structural parameters to the special MR relaxation features. The demonstrated “19F relaxation switch” phenomenon is potentially useful for monitoring cellular endosomal functionality. PMID:21761488

Cortical PAR polarity proteins promote robust cytokinesis during asymmetric cell division

PubMed Central

Jordan, Shawn N.; Davies, Tim; Zhuravlev, Yelena; Dumont, Julien; Shirasu-Hiza, Mimi

2016-01-01

Cytokinesis, the physical division of one cell into two, is thought to be fundamentally similar in most animal cell divisions and driven by the constriction of a contractile ring positioned and controlled solely by the mitotic spindle. During asymmetric cell divisions, the core polarity machinery (partitioning defective [PAR] proteins) controls the unequal inheritance of key cell fate determinants. Here, we show that in asymmetrically dividing Caenorhabditis elegans embryos, the cortical PAR proteins (including the small guanosine triphosphatase CDC-42) have an active role in regulating recruitment of a critical component of the contractile ring, filamentous actin (F-actin). We found that the cortical PAR proteins are required for the retention of anillin and septin in the anterior pole, which are cytokinesis proteins that our genetic data suggest act as inhibitors of F-actin at the contractile ring. Collectively, our results suggest that the cortical PAR proteins coordinate the establishment of cell polarity with the physical process of cytokinesis during asymmetric cell division to ensure the fidelity of daughter cell formation. PMID:26728855

Carbon-14 dating of small samples by proportional counting.

PubMed

Harbottle, G; Sayre, E V; Stoenner, R W

1979-11-09

Conventional carbon-14 dating by means of gas proportional counters has been extended to samples containing as little as 10 milligrams of carbon. The accuracy of the dating procedure has been checked by dating sequoia tree-ring samples of the 1st century A.D. and B.C. and an oak tree-ring sample of the 19th century A.D.

Aim44p regulates phosphorylation of Hof1p to promote contractile ring closure during cytokinesis in budding yeast

PubMed Central

Wolken, Dana M. Alessi; McInnes, Joseph; Pon, Liza A.

2014-01-01

Whereas actomyosin and septin ring organization and function in cytokinesis are thoroughly described, little is known regarding the mechanisms by which the actomyosin ring interacts with septins and associated proteins to coordinate cell division. Here we show that the protein product of YPL158C, Aim44p, undergoes septin-dependent recruitment to the site of cell division. Aim44p colocalizes with Myo1p, the type II myosin of the contractile ring, throughout most of the cell cycle. The Aim44p ring does not contract when the actomyosin ring closes. Instead, it forms a double ring that associates with septin rings on mother and daughter cells after cell separation. Deletion of AIM44 results in defects in contractile ring closure. Aim44p coimmunoprecipitates with Hof1p, a conserved F-BAR protein that binds both septins and type II myosins and promotes contractile ring closure. Deletion of AIM44 results in a delay in Hof1p phosphorylation and altered Hof1p localization. Finally, overexpression of Dbf2p, a kinase that phosphorylates Hof1p and is required for relocalization of Hof1p from septin rings to the contractile ring and for Hof1p-triggered contractile ring closure, rescues the cytokinesis defect observed in aim44∆ cells. Our studies reveal a novel role for Aim44p in regulating contractile ring closure through effects on Hof1p. PMID:24451263

Methodology for Mechanical Property Testing of Fuel Cladding Using a Expanded Plug Wedge Test

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

Jiang, Hao; Wang, Jy-An John

2014-01-01

An expanded plug method was developed earlier for determining the tensile properties of irradiated fuel cladding. This method tests fuel rod cladding ductility by utilizing an expandable plug to radially stretch a small ring of irradiated cladding material. The circumferential or hoop strain is determined from the measured diametrical expansion of the ring. A developed procedure is used to convert the load circumferential strain data from the ring tests into material pseudo-stress-strain curves, from which material properties of the cladding can be extracted. However, several deficiencies existed in this expanded-plug test that can impact the accuracy of test results, suchmore » as that the large axial compressive stress resulted from the expansion plug test can potentially induce the shear failure mode of the tested specimen. Moreover, highly nonuniform stress and strain distribution in the deformed clad gage section and significant compressive stresses, induced by bending deformation due to clad bulging effect, will further result in highly nonconservative estimates of the mechanical properties for both strength and ductility of the tested clad. To overcome the aforementioned deficiencies associated with the current expansion plug test, systematic studies have been conducted. By optimizing the specific geometry designs, selecting the appropriate material for the expansion plug, and adding new components into the testing system, a modified expansion plug testing protocol has been developed. A general procedure was also developed to determine the hoop stress in the tested ring specimen. A scaling factor, -factor, was used to convert the ring load Fring into hoop stress , and is written as _ = F_ring/tl , where t is the clad thickness and l is the clad length. The generated stress-strain curve agrees well with the associated tensile test data in both elastic and plastic deformation regions.« less

1-(4-Chloro-2-fluoro-phen-yl)-4-difluoro-methyl-3-methyl-1H-1,2,4-triazol-5(4H)-one.

PubMed

Ren, Dong-Mei; Wang, Yong-Yi

2012-04-01

In the crystal structure of the title compound, C(10)H(7)ClF(3)N(3)O, pairs of mol-ecules are connected into dimers via pairs of C-H⋯O hydrogen bonds. The dihedral angle between the benzene ring and attached triazolone ring is 53.2 (1)°.

18F-Positron Emitting/Trimethine Cyanine-Fluorescent Contrast for Image-Guided Prostate Cancer Management.

PubMed

Kommidi, Harikrishna; Guo, Hua; Nurili, Fuad; Vedvyas, Yogindra; Jin, Moonsoo M; McClure, Timothy D; Ehdaie, Behfar; Sayman, Haluk B; Akin, Oguz; Aras, Omer; Ting, Richard

2018-05-10

[ 18/19 F]-4, an anionic GCPII/PSMA inhibitor for image-guided intervention in prostate cancer, is described. [ 19 F]-4 is radiolabeled with a radiochemical yield that is ≥27% and a molar activity of 190 ± 50 mCi/μmol in a <1 h, one-step, aqueous isotopic exchange reaction. [ 19 F]-4 allows PSMA expression to be imaged by fluorescence (FL) and [ 18 F]-PET. PC3-PIP (PSMA-positive, EC 50 = 6.74 ± 1.33 nM) cancers are specifically delineated in mice that bear 3 million (18 mg) PC3-PIP and PC3 (control, PSMA-negative) cells. Colocalization of [ 18/19 F]-4 PET, fluorescence, scintillated biodistribution, and PSMA expression are observed.

Analog detection for cavity lifetime spectroscopy

DOEpatents

Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

2001-05-15

An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

Analog detection for cavity lifetime spectroscopy

DOEpatents

Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

2003-01-01

An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

Experimental nuclear physics

NASA Astrophysics Data System (ADS)

An earlier study of unusual electromagnetic decays in (sup 86)Zr was extended in order to make comparisons with its isotone (sup 84)Sr and with (sup 84)Zr. The K=14 (t(sub 1/2) = 70 ns) high-spin isomer in (sup 176)W was found to have a 13 percent branch directly to the K=O ground-state band, one of the strongest violations of K-selection rules known. A new program to search for a predicted region of oblate deformation involving neutron deficient isotopes in the Rn/Fr/Ra region was begun. In the area of nuclear astrophysics, as part of a study of the onset of the rp-Process, a set of measurements searching for possible new resonances for (sup 14)O+(alpha) and (sup 17)F+p reactions was completed and a coincidence experiment measuring the (sup 19)F ((sup 3)He,t) (sup 19)Ne(alpha) (sup 15)O and (sup 19)F ((sup 3)He,t) (sup 19)Ne(p) (sup 18)F reactions in order to determine the rates of the (sup 18)F(p,(alpha)) (sup 15)O and (sup 18)F(p,(gamma)) (sup 19)Ne reactions was begun. Experimental measurements of (beta)n(alpha) coincidences from the (sup 15)N(d,p) (sup 16)N((beta)- (nu)) (sup 16)O((alpha)) (sup 12)C reaction have also been completed and are currently being analyzed to determine the rate of the (sup 12)C((alpha),(gamma)) reaction. In the APEX collaboration, we have completed the assembly and testing of two position-sensitive Na barrels which surround the axial silicon detector arrays and serve as the e(sup +) triggers by detecting their back-to-back annihilation quanta were completed. The HI@AGS and RHIC collaborations, construction and implementation activities associated with the space-time-tracker detector and in the design of the central detector for the PHENIX experiment were carried out. Operation of the ESTU tandem accelerator has been reliable, delivering beam on target at terminal voltages as high as 19.3 MV and running for as long as 143 days between tank openings. Fabrication and bench testing of a new negative ion source system have been completed.

Self-oscillation of standing spin wave in ring resonator with proportional-integral-derivative control

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

Peng, B.; Urazuka, Y.; Chen, H.

2014-05-07

We report on numerical analysis on self-oscillation of standing spin wave excited in a nanostructured active ring resonator, consists of a ferromagnetic nanowire with perpendicular anisotropy. The confined resonant modes are along the nanowire length. A positive feedback with proportional-integral-derivative gain control was adopted in the active ring. Stable excitation of the 1st order standing spin wave has been demonstrated with micromagnetic simulations, taking into account the thermal effect with a random field model. The stationary standing spin wave with a pre-determined set variable of precession amplitude was attained within 20 ns by optimizing the proportional-integral-derivative gain control parameters. The resultmore » indicates that a monochromatic oscillation frequency f{sub osc} is extracted from the initial thermal fluctuation state and selectively amplified with the positive feedback loop. The obtained f{sub osc} value of 5.22 GHz practically agrees with the theoretical prediction from dispersion relation of the magneto static forward volume wave. It was also confirmed that the f{sub osc} change due to the temperature rise can be compensated with an external perpendicular bias field H{sub b}. The observed quick compensation time with an order of nano second suggests the fast operation speed in the practical device application.« less

A fast low-power optical memory based on coupled micro-ring lasers

NASA Astrophysics Data System (ADS)

Hill, Martin T.; Dorren, Harmen J. S.; de Vries, Tjibbe; Leijtens, Xaveer J. M.; den Besten, Jan Hendrik; Smalbrugge, Barry; Oei, Yok-Siang; Binsma, Hans; Khoe, Giok-Djan; Smit, Meint K.

2004-11-01

The increasing speed of fibre-optic-based telecommunications has focused attention on high-speed optical processing of digital information. Complex optical processing requires a high-density, high-speed, low-power optical memory that can be integrated with planar semiconductor technology for buffering of decisions and telecommunication data. Recently, ring lasers with extremely small size and low operating power have been made, and we demonstrate here a memory element constructed by interconnecting these microscopic lasers. Our device occupies an area of 18 × 40µm2 on an InP/InGaAsP photonic integrated circuit, and switches within 20ps with 5.5fJ optical switching energy. Simulations show that the element has the potential for much smaller dimensions and switching times. Large numbers of such memory elements can be densely integrated and interconnected on a photonic integrated circuit: fast digital optical information processing systems employing large-scale integration should now be viable.

Mimas Looks On

NASA Image and Video Library

2004-09-07

Lonely Mimas swings around Saturn, seeming to gaze down at the planet's splendid rings. The outermost, narrow F ring is visible here and exhibits some clumpy structure near the bottom of the frame. The shadow of Saturn's southern hemisphere stretches almost entirely across the rings. Mimas is 398 kilometers (247 miles) wide. The image was taken with the Cassini spacecraft narrow angle camera on August 15, 2004, at a distance of 8.8 million kilometers (5.5 million miles) from Saturn, through a filter sensitive to visible red light. The image scale is 53 kilometers (33 miles) per pixel. Contrast was slightly enhanced to aid visibility.almost entirely across the rings. Mimas is 398 kilometers (247 miles) wide. http://photojournal.jpl.nasa.gov/catalog/PIA06471

Status and outlook of the CRYRING@ESR project

NASA Astrophysics Data System (ADS)

Geithner, W.; Andelkovic, Z.; Beck, D.; Bräuning, H.; Bräuning-Demian, A.; Danared, H.; Dimopoulou, C.; Engström, M.; Fedotova, S.; Gorda, O.; Herfurth, F.; Hess, R.; Källberg, A.; Kleffner, C.; Kotovskiy, N.; Kraus, I.; Lestinsky, M.; Litvinov, S.; Nolden, F.; Reiter, A.; Sieber, T.; Steck, M.; Vorobyev, G.

2017-11-01

Once operational, CRYRING@ESR will store and decelerate ions delivered by the experimental storage ring ESR at energies well below those of ESR. In addition to that, CRYRING@ESR has an electron cooler operating with an ultracold electron beam, allowing to provide cooled ion beams for precision experiments. These ions will be delivered to a broad range of experiments presently in preparation; either in-ring or extracted to a dedicated beamline for experiments. An overview and status report of the installation and commissioning of the CRYRING-@ESR storage ring for highly charged ions at the GSI Helmholtzzentrum für Schwerionenforschung is presented. The installation of this storage ring started in 2014 and was completing end of 2016, when this publication was written.

Expedited Synthesis of Fluorine-18 Labeled Phenols. A Missing Link in PET Radiochemistry

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

Katzenellenbogen, John A.; Zhou, Dong

Fluorine-18 (F-18) is arguably the most valuable radionuclide for positron emission tomographic (PET) imaging. However, while there are many methods for labeling small molecules with F-18 at aliphatic positions and on electron-deficient aromatic rings, there are essentially no reliable and practical methods to label electron-rich aromatic rings such as phenols, with F-18 at high specific activity. This is disappointing because fluorine-labeled phenols are found in many drugs; there are also many interesting plant metabolites and hormones that contain either phenols or other electron-rich aromatic systems such as indoles whose metabolism, transport, and distribution would be interesting to study if theymore » could readily be labeled with F-18. Most approaches to label phenols with F-18 involve the labeling of electron-poor precursor arenes by nucleophilic aromatic substitution, followed by subsequent conversion to phenols by oxidation or other multi-step sequences that are often inefficient and time consuming. Thus, the lack of good methods for labeling phenols and other electron-rich aromatics with F-18 at high specific activity represents a significant methodological gap in F-18 radiochemistry that can be considered a “Missing Link in PET Radiochemistry”. The objective of this research project was to develop and optimize a series of unusual synthetic transformations that will enable phenols (and other electron-rich aromatic systems) to be labeled with F-18 at high specific activity, rapidly, reliably, and conveniently, thereby bridging this gap. Through the studies conducted with support of this project, we have substantially advanced synthetic methodology for the preparation of fluorophenols. Our progress is presented in detail in the sections below, and much has been published or presented publication; other components are being prepared for publication. In essence, we have developed a completely new method to prepare o-fluorophenols from non-aromatic precursors (diazocyclohexenones) by a novel reaction sequence that uses fluoride ion as a precursor and various activating electrophiles, and we have improved methods for the preparation of heterodiaryl iodonium salts. Both methods have been used to prepare interesting potential radiotracers. Other advances have been made in labeling dendrimeric nanoparticle structures of increasing interest for multimodal imaging and in advancing labeling through fluorosilane bonds. Thus, the progress we have made substantially fills the significant gap in PET radiochemistry that we originally identified, and it provides for the field new methodology that can be applied to a number of current challenges, including the preparation of several molecules of interest as radiotracers, such as 2-[18F]Fluoroestradiol (2-FES) and m-fluorotyrosine, which we have illustrated. These methods can be used by any skilled radiochemist interesting in preparing these agents or similar fluorine-18 labeled electron-rich arene systems of interested for PET biological imaging in the most general sense.« less

Intermolecular interactions between σ- and π-holes of bromopentafluorobenzene and pyridine: computational and experimental investigations.

PubMed

Yang, Fang-Ling; Yang, Xing; Wu, Rui-Zhi; Yan, Chao-Xian; Yang, Fan; Ye, Weichun; Zhang, Liang-Wei; Zhou, Pan-Pan

2018-04-25

The characters of σ- and π-holes of bromopentafluorobenzene (C6F5Br) enable it to interact with an electron-rich atom or group like pyridine which possesses an electron lone-pair N atom and a π ring. Theoretical studies of intermolecular interactions between C6F5Br and C5H5N have been carried out at the M06-2X/aug-cc-pVDZ level without and with the counterpoise method, together with single point calculations at M06-2X/TZVP, wB97-XD/aug-cc-pVDZ and CCSD(T)/aug-cc-pVDZ levels. The σ- and π-holes of C6F5Br exhibiting positive electrostatic potentials make these sites favorably interact with the N atom and the π ring of C5H5N with negative electrostatic potentials, leading to five different dimers connected by a σ-holen bond, a σ-holeπ bond or a π-holeπ bond. Their geometrical structures, characteristics, nature and spectroscopy behaviors were systematically investigated. EDA analyses reveal that the driving forces in these dimers are different. NCI, QTAIM and NBO analyses confirm the existence of intermolecular interactions formed via σ- and π-holes of C6F5Br and the N atom and the π ring of C5H5N. The experimental IR and Raman spectra gave us important information about the formation of molecular complexes between C6F5Br and C5H5N. We expect that the results could provide valuable insights into the investigation of intermolecular interactions involving σ- and π-holes.

49 CFR Appendix A to Part 214 - Schedule of Civil Penalties 1

Code of Federal Regulations, 2013 CFR

2013-10-01

... use ring bouys 1,500 (f)(i) Failure to provide skiff 1,000 2,500 (ii) Failure to use skiff 1,500 214... warning signal 1,500 3,000 (f)(1) Assignment of non-qualified person as watchman/lookout 3,000 5,000 (2... charge of providing on-track safety for a roadway work group 2,000 4,000 (e) (1) (1) (f) Roadway...

Mutational analysis of TRAF6 reveals a conserved functional role of the RING dimerization interface and a potentially necessary but insufficient role of RING-dependent TRAF6 polyubiquitination towards NF-κB activation

PubMed Central

Megas, Charilaos; Hatzivassiliou, Eudoxia G.; Yin, Qian; Vignali, Dario A.A.; Mosialos, George

2011-01-01

TRAF6 is an E3 ubiquitin ligase that plays a pivotal role in the activation of NF-κB by innate and adaptive immunity stimuli. TRAF6 consists of a highly conserved carboxyl terminal TRAF-C domain which is preceded by a coiled coil domain and an amino terminal region that contains a RING domain and a series of putative zinc-finger motifs. The TRAF-C domain contributes to TRAF6 oligomerization and mediates the interaction of TRAF6 with upstream signaling molecules whereas the RING domain comprises the core of the ubiquitin ligase catalytic domain. In order to identify structural elements that are important for TRAF6-induced NF-κB activation, mutational analysis of the TRAF-C and RING domains was performed. Alterations of highly conserved residues of the TRAF-C domain of TRAF6 did not affect significantly the ability of the protein to activate NF-κB. On the other hand a number of functionally important residues (L77, Q82, R88, F118, N121 and E126) for the activation of NF-κB were identified within the RING domain of TRAF6. Interestingly, several homologues of these residues in TRAF2 were shown to have a conserved functional role in TRAF2-induced NF-κB activation and lie at the dimerization interface of the RING domain. Finally, whereas alteration of Q82, R88 and F118 compromised both the K63-linked polyubiquitination of TRAF6 and its ability to activate NF-κB, alteration of L77, N121 and E126 diminished the NF-κB activating function of TRAF6 without affecting TRAF6 K63-linked polyubiquitination. Our results support a conserved functional role of the TRAF RING domain dimerization interface and a potentially necessary but insufficient role for RING-dependent TRAF6 K63-linked polyubiquitination towards NF-κB activation in cells. PMID:21185369

Mutational analysis of TRAF6 reveals a conserved functional role of the RING dimerization interface and a potentially necessary but insufficient role of RING-dependent TRAF6 polyubiquitination towards NF-κB activation.

PubMed

Megas, Charilaos; Hatzivassiliou, Eudoxia G; Yin, Qian; Marinopoulou, Elli; Hadweh, Paul; Vignali, Dario A A; Mosialos, George

2011-05-01

TRAF6 is an E3 ubiquitin ligase that plays a pivotal role in the activation of NF-κB by innate and adaptive immunity stimuli. TRAF6 consists of a highly conserved carboxyl terminal TRAF-C domain which is preceded by a coiled coil domain and an amino terminal region that contains a RING domain and a series of putative zinc-finger motifs. The TRAF-C domain contributes to TRAF6 oligomerization and mediates the interaction of TRAF6 with upstream signaling molecules whereas the RING domain comprises the core of the ubiquitin ligase catalytic domain. In order to identify structural elements that are important for TRAF6-induced NF-κB activation, mutational analysis of the TRAF-C and RING domains was performed. Alterations of highly conserved residues of the TRAF-C domain of TRAF6 did not affect significantly the ability of the protein to activate NF-κB. On the other hand a number of functionally important residues (L77, Q82, R88, F118, N121 and E126) for the activation of NF-κB were identified within the RING domain of TRAF6. Interestingly, several homologues of these residues in TRAF2 were shown to have a conserved functional role in TRAF2-induced NF-κB activation and lie at the dimerization interface of the RING domain. Finally, whereas alteration of Q82, R88 and F118 compromised both the K63-linked polyubiquitination of TRAF6 and its ability to activate NF-κB, alteration of L77, N121 and E126 diminished the NF-κB activating function of TRAF6 without affecting TRAF6 K63-linked polyubiquitination. Our results support a conserved functional role of the TRAF RING domain dimerization interface and a potentially necessary but insufficient role for RING-dependent TRAF6 K63-linked polyubiquitination towards NF-κB activation in cells. Copyright © 2010 Elsevier Inc. All rights reserved.

Recent photometric monitoring of KIC 8462852, the detection of a potential repeat of the Kepler day 1540 dip and a plausible model

NASA Astrophysics Data System (ADS)

Bourne, R.; Gary, B. L.; Plakhov, A.

2018-04-01

This paper presents V- and g΄-band observations of the F2V star KIC 8462852, which exhibited enigmatic fade patterns in Kepler mission data. We introduce a transit simulation model for interpretation of these fades, and use it to interpret a 2017 August dip as a repeat of the Kepler day 1540 dip (D1540). We suggest the 2017 August and D1540 dips may be caused by a brown dwarf and an associated ring system in a 1601-d elliptical orbit. Transiting icy moons of the proposed brown dwarf, sublimating near periapsis like comets, could provide an explanation for the significant dips observed by Kepler, as well as the recent 2017 May to October dips and the long-term variation in flux detected by Simon et al. Whereas the presence of such a ring structure is attractive for its ability to explain short-term fade events, we do not address how such a ring system can be created and maintained. This speculation predicted a brightening of ˜1 per cent that occurred during October 2017. In addition, this scenario predicts that a set of dimming events, similar to those in 2013 (Kepler) and in 2017 (reported here), can be expected to repeat during 2021 October to 2022 January and a repeat of D1540 should occur on 2021 December 27.

An Analysis of the Effect of ASVAB Waivers on A-School Academic Attrition

DTIC Science & Technology

1990-12-01

6224 6537 Boiler Technician ( 4YO ) (BT4) 6260 6486 Boiler Technician (6YO) 614F 614H 6488 Cryptologic Maintenance Technician (CTM) 605A 6161 Electronics...Systems Technician Electrical (6YO) (GSE) 606C 614N 614R Gas Turbine Systems Technician Mechanical (GSM) 614W 614T Machinist’s Mate ( 4YO ) (M*4) 6262...19.05) 4 (17.39) 58 M.( 4YO 372 (29.29) 54 (29.19) 29 (38.67) 455 IM6YO 30 (9.87) 4 (9.30) * 34 OH 18 (69.23) 4 (100) * 22 OS 296 (18.90) 42 (28.19) 6

A Pauson-Khand and ring-expansion approach to the aquariane ring system.

PubMed

Thornton, Paul D; Burnell, D Jean

2006-07-20

[Structure: see text] The carbocyclic ring system of the aquariolide diterpenes has been synthesized by two routes involving a diastereoselective Pauson-Khand reaction and subsequent ring expansion. In one route, a tetracyclic enone was elaborated to generate the nine-membered ring by Grob fragmentation. In the second approach, a spirocyclic tricycle underwent a facile anionic oxy-Cope rearrangement to complete the synthesis of the desired ring system.