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Sample records for high alpha stability

  1. A computational study on directional stability of chine-shaped forebodies at high-alpha

    NASA Technical Reports Server (NTRS)

    Ravi, R.; Mason, William H.

    1992-01-01

    CFD is employed to study the flowfields over chine-shaped forebodies at low-speed high-angle-of-attack conditions with sideslip. This study is conducted to define forebody geometries that provide good directional stability characteristics under these conditions. An analytically defined generic forebody model is developed and a systematic examination of forebody shapes is performed to determine which shapes promote a positive contribution to directional stability at high-alpha. Results of the initial parametric study and some guidelines for aerodynamic design to promote positive directional stability are presented.

  2. A computational examination of directional stability for smooth and chined forebodies at high-alpha

    NASA Technical Reports Server (NTRS)

    Ravi, Ramakrishnan; Mason, William H.

    1992-01-01

    Computational Fluid Dynamics (CFD) has been used to study aircraft forebody flowfields at low-speed, angle-of-attack conditions with sideslip. The purpose is to define forebody geometries which provide good directional stability characteristics under these conditions. The flows over the experimentally investigated F-5A forebody and chine type configuration, previously computed by the authors, were recomputed with better grid topology and resolution. The results were obtained using a modified version of CFL3D (developed at NASA Langley) to solve either the Euler equations or the Reynolds equations employing the Baldwin-Lomax turbulence model with the Degani-Schiff modification to account for massive crossflow separation. Based on the results, it is concluded that current CFD methods can be used to investigate the aerodynamic characteristics of forebodies to achieve desirable high angle-of-attack characteristics. An analytically defined generic forebody model is described, and a parametric study of various forebody shapes was then conducted to determine which shapes promote a positive contribution to directional stability at high angle-of-attack. An unconventional approach for presenting the results is used to illustrate how the positive contribution arises. Based on the results of this initial parametric study, some guidelines for aerodynamic design to promote positive directional stability are presented.

  3. Impact of high-alpha aerodynamics on dynamic stability parameters of aircraft and missiles

    NASA Technical Reports Server (NTRS)

    Malcolm, G. N.

    1981-01-01

    The aerodynamic phenomena associated with high angles of attack and their effects on the dynamic stability characteristics of airplane and missile configurations are examined. Information on dynamic effects is limited. Steady flow phenomena and their effects on the forces and moments are reviewed. The effects of asymmetric vortices and of vortex bursting on the dynamic response of flight vehicles are reviewed with respect to their influence on: (1) nonlinearity of aerodynamic coefficients with attitude, rates, and accelerations; (2) cross coupling between longitudinal and lateral directional models of motion; (3) time dependence and hysteresis effects; (4) configuration dependencey; and (5) mathematical modeling of the aerodynamics.

  4. Condition stabilization for Aspergillus niger FCBP-198 and its hyperactive mutants to yield high titres of alpha-amylase.

    PubMed

    Shafique, Sobiya; Bajwa, Rukhsana; Shafique, Shazia

    2010-01-01

    A number of substrates were tested for the cultivation of microorganisms to produce a host of enzymes. The effect of different substrates (wheat and rice straw, sugar cane waste, wood waste), incubation temperatures (20-40 degrees C), initial pH levels (3.5-9.0), incubation periods (0-72 hours) and nitrogen sources (ammonium sulfate, urea, peptone, yeast extract, sodium nitrate) on growth and alpha-amylase activity was studied for the native and mutant strains. Maximum enzyme activity was observed at 1.5% wheat straw for Aspergillus niger FCBP-198 and An-Ch-4.7 and at 2% wheat straw for An-UV-5.6, with sodium nitrate as a principle nitrogen source. The optimum temperature for maximum enzyme activity was 30 degrees C for the parental strain, while An-UV-5.6 and An-Ch-4.7 thrived well at 32.5 degrees C. The best conditions of pH and incubation duration were 4.5 and 48 hours, respectively, for all the strains. Mass production under preoptimized growth conditions demonstrated the suitability of wheat straw for swift mycelial colonization and viability. PMID:20734811

  5. High gas flow alpha detector

    DOEpatents

    Bolton, R.D.; Bounds, J.A.; Rawool-Sullivan, M.W.

    1996-05-07

    An alpha detector for application in areas of high velocity gas flows, such as smokestacks and air vents. A plurality of spaced apart signal collectors are placed inside an enclosure, which would include smokestacks and air vents, in sufficient numbers to substantially span said enclosure so that gas ions generated within the gas flow are electrostatically captured by the signal collector means. Electrometer means and a voltage source are connected to the signal collectors to generate an electrical field between adjacent signal collectors, and to indicate a current produced through collection of the gas ions by the signal collectors. 4 figs.

  6. High gas flow alpha detector

    DOEpatents

    Bolton, Richard D.; Bounds, John A.; Rawool-Sullivan, Mohini W.

    1996-01-01

    An alpha detector for application in areas of high velocity gas flows, such as smokestacks and air vents. A plurality of spaced apart signal collectors are placed inside an enclosure, which would include smokestacks and air vents, in sufficient numbers to substantially span said enclosure so that gas ions generated within the gas flow are electrostatically captured by the signal collector means. Electrometer means and a voltage source are connected to the signal collectors to generate an electrical field between adjacent signal collectors, and to indicate a current produced through collection of the gas ions by the signal collectors.

  7. Stability against {alpha} decay of some recently observed superheavy elements

    SciTech Connect

    Roy Chowdhury, Partha; Gangopadhyay, G.; Bhattacharyya, Abhijit

    2011-02-15

    The probability of {alpha}-particle emission for some recently observed superheavy nuclei (SHN) are investigated. The {alpha}-decay half-lives of SHN are calculated in a quantum tunneling model with density-dependent M3Y (DDM3Y) effective nuclear interaction using theoretical and measured Q{sub {alpha}} values. We determine the density distribution of {alpha} and daughter nuclei from the relativistic mean-field (RMF) theory using FSUGold force, NL3, and TM1 parameter sets. The double-folded nuclear potential is numerically calculated in a more microscopic manner using these density distributions. The estimated values of {alpha}-decay half-lives are in good agreement with the recent data. We compare our results with recently detected {alpha}-decay chains from a new element with atomic number Z=117 reported by the Joint Institute for Nuclear Research, Dubna. Finally, we determine the half-lives of superheavy elements with Z=108-120 and neutron number N=152-190 to explore the long-standing predictions of the existence of an 'island of stability' due to possible spherical proton (Z{approx}114) and neutron (N{approx}184) shell closures.

  8. Structural Characteristics of the Alpha-Synuclein Oligomers Stabilized By the Flavonoid Baicalein

    SciTech Connect

    Hong, D.-P.; Fink, A.L.; Uversky, V.N.

    2009-05-18

    The flavonoid baicalein inhibits fibrillation of alpha-synuclein, which is a major component of Lewy bodies in Parkinson's disease. It has been known that baicalein induces the formation of alpha-synuclein oligomers and consequently prevents their fibrillation. In order to evaluate the structural properties of baicalein-stabilized oligomers, we purified oligomer species by HPLC and examined their stability and structure by CD, Fourier transform infrared spectroscopy, size exclusion chromatography HPLC, small-angle X-ray scattering, and atomic force microscopy. Baicalein-stabilized oligomers are beta-sheet-enriched according to CD and Fourier transform infrared spectroscopy analyses. They did not form fibrils even after very prolonged incubation. From small-angle X-ray scattering data and atomic force microscopy images, the oligomers were characterized as quite compact globular species. Oligomers were extremely stable, with a GdmCl C(m)=3.3 M. This high stability explains the previously observed inhibition properties of baicalein against alpha-synuclein fibrillation. These baicalein-stabilized oligomers, added to the solution of aggregating alpha-synuclein, were able to noticeably inhibit its fibrillation. After prolonged coincubation, short fibrils were formed, suggesting an effective interaction of oligomers with monomeric alpha-synuclein. Membrane permeability tests suggested that the baicalein-stabilized oligomers had a mild effect on the integrity of the membrane surface. This effect was rather similar to that of the monomeric protein, suggesting that targeted stabilization of certain alpha-synuclein oligomers might offer a potential strategy for the development of novel Parkinson's disease therapies.

  9. Thermal stability of alpha-amylase in aqueous cosolvent systems.

    PubMed

    Yadav, Jay Kant; Prakash, V

    2009-09-01

    The activity and thermal stability of alpha-amylase were studied in the presence of different concentrations of trehalose, sorbitol, sucrose and glycerol. The optimum temperature of the enzyme was found to be 50 +/- 2 degrees C. Further increase in temperature resulted in irreversible thermal inactivation of the enzyme. In the presence of cosolvents, the rate of thermal inactivation was found to be significantly reduced. The apparent thermal denaturation temperature (Tm) app and activation energy (Ea) of alpha-amylase were found to be significantly increased in the presence of cosolvents in a concentration-dependent manner. In the presence of 40% trehalose, sorbitol, sucrose and glycerol, increments in the (Tm)app were 20 degrees C, 14 degrees C, 13 degrees C and 9 degrees C, respectively. The Ea of thermal denaturation of alpha-amylase in the presence of 20% (w/v) trehalose, sorbitol, sucrose and glycerol was found to be 126, 95, 90 and 43 kcal/mol compared with a control value of 40 kcal/mol. Intrinsic and 8-anilinonaphathalene-1-sulphonic acid (ANS) fluorescence studies indicated that thermal denaturation of the enzyme was accompanied by exposure of the hydrophobic cluster on the protein surface. Preferential interaction parameters indicated extensive hydration of the enzyme in the presence of cosolvents. PMID:19805899

  10. Fourth High Alpha Conference, volume 1

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The goal of the Fourth High Alpha Conference was to focus on the flight validation of high angle-of-attack technologies and provide an in-depth review of the latest high angle-of-attack activities. Areas that were covered include: high angle-of-attack aerodynamics, propulsion and inlet dynamics, thrust vectoring, control laws and handling qualities, tactical utility, and forebody controls.

  11. Fourth High Alpha Conference, volume 2

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The goal of the Fourth High Alpha Conference, held at the NASA Dryden Flight Research Center on July 12-14, 1994, was to focus on the flight validation of high angle of attack technologies and provide an in-depth review of the latest high angle of attack activities. Areas that were covered include high angle of attack aerodynamics, propulsion and inlet dynamics, thrust vectoring, control laws and handling qualities, and tactical utility.

  12. Prediction of the fusion alpha density profile in ITER from local marginal stability to Alfvén eigenmodes

    NASA Astrophysics Data System (ADS)

    Waltz, R. E.; Bass, E. M.

    2014-10-01

    A simple radial transport code for predicting the fusion alpha density profiles in an ITER burning plasma unstable to Alfvén eigenmodes (AEs) is illustrated. This extends earlier work by Angioni et al (2009 Nucl. Fusion 49 055013) treating the fusion alpha transport from high-n micro-turbulence to include marginal stability (or ‘stiff’) transport from alpha-driven low-n AEs. The local alpha density gradient AE thresholds are provided by physically realistic linear gyrokinetic code simulations. The transported alpha density profiles are compared to the alpha classical slowing-down profiles dependent on the birth rate source profiles. The base case thermal plasma (and hence source) profiles are taken from a theory-based core transport and H-mode pedestal prediction of ITER performance by Kinsey et al (2011 Nucl. Fusion 51 083001). The distinction between the alpha particle and the much smaller alpha energy transport loss is emphasized. The AE transport is localized to the mid-core radii with the high-n micro-turbulence controlling the transport loss of low energy alphas at the edge. Edge energy loss is about 100-fold smaller than particle loss. Even with the worst case boundary condition, only about 0.1% of net heating is lost and escaping alphas can be characterized as very hot helium.

  13. Nucleolin links to arsenic-induced stabilization of GADD45alpha mRNA.

    PubMed

    Zhang, Yadong; Bhatia, Deepak; Xia, Hongfeng; Castranova, Vince; Shi, Xianglin; Chen, Fei

    2006-01-01

    The present study shows that arsenic induces GADD45alpha (growth arrest and DNA damage inducible gene 45alpha) mainly through post-transcriptional mechanism. Treatment of the human bronchial epithelial cell line, BEAS-2B, with arsenic(III) chloride (As3+) resulted in a significant increase in GADD45alpha protein and mRNA. However, As3+ only exhibited a marginal effect on the transcription of the GADD45alpha gene. The accumulation of GADD45alpha mRNA is largely achieved by the stabilization of GADD45alpha mRNA in the cellular response to As3+. As3+ is able to induce binding of mRNA stabilizing proteins, nucleolin and less potently, HuR, to the GADD45alpha mRNA. Although As3+ was unable to affect the expression of nucleolin, treatment of the cells with As3+ resulted in re-distribution of nucleolin from nucleoli to nucleoplasm. Silencing of the nucleolin mRNA by RNA interference reversed As3+-induced stabilization of the GADD45alpha mRNA and accumulation of the GADD45alpha protein. Stabilization of GADD45alpha mRNA, thus, represents a novel mechanism contributing to the production of GADD45alpha and cell cycle arrest in response to As3+. PMID:16421274

  14. Molecular Mechanism of AHSP-Mediated Stabilization of Alpha-Hemoglobin

    SciTech Connect

    Feng,L.; Gell, D.; Zhou, S.; Gu, L.; Kong, Y.; Li, J.; Hu, M.; Yan, N.; Lee, C.; et al.

    2005-01-01

    Hemoglobin A (HbA), the oxygen delivery system in humans, comprises two alpha and two beta subunits. Free alpha-hemoglobin (alphaHb) is unstable, and its precipitation contributes to the pathophysiology of beta thalassemia. In erythrocytes, the alpha-hemoglobin stabilizing protein (AHSP) binds alphaHb and inhibits its precipitation. The crystal structure of AHSP bound to Fe(II)-alphaHb reveals that AHSP specifically recognizes the G and H helices of alphaHb through a hydrophobic interface that largely recapitulates the alpha1-beta1 interface of hemoglobin. The AHSP-alphaHb interactions are extensive but suboptimal, explaining why beta-hemoglobin can competitively displace AHSP to form HbA. Remarkably, the Fe(II)-heme group in AHSP bound alphaHb is coordinated by the distal but not the proximal histidine. Importantly, binding to AHSP facilitates the conversion of oxy-alphaHb to a deoxygenated, oxidized [Fe(III)], nonreactive form in which all six coordinate positions are occupied. These observations reveal the molecular mechanisms by which AHSP stabilizes free alphaHb.

  15. Protein engineering in the alpha-amylase family: catalytic mechanism, substrate specificity, and stability.

    PubMed

    Svensson, B

    1994-05-01

    Most starch hydrolases and related enzymes belong to the alpha-amylase family which contains a characteristic catalytic (beta/alpha)8-barrel domain. Currently known primary structures that have sequence similarities represent 18 different specificities, including starch branching enzyme. Crystal structures have been reported in three of these enzyme classes: the alpha-amylases, the cyclodextrin glucanotransferases, and the oligo-1,6-glucosidases. Throughout the alpha-amylase family, only eight amino acid residues are invariant, seven at the active site and a glycine in a short turn. However, comparison of three-dimensional models with a multiple sequence alignment suggests that the diversity in specificity arises by variation in substrate binding at the beta-->alpha loops. Designed mutations thus have enhanced transferase activity and altered the oligosaccharide product patterns of alpha-amylases, changed the distribution of alpha-, beta- and gamma-cyclodextrin production by cyclodextrin glucanotransferases, and shifted the relative alpha-1,4:alpha-1,6 dual-bond specificity of neopullulanase. Barley alpha-amylase isozyme hybrids and Bacillus alpha-amylases demonstrate the impact of a small domain B protruding from the (beta/alpha)8-scaffold on the function and stability. Prospects for rational engineering in this family include important members of plant origin, such as alpha-amylase, starch branching and debranching enzymes, and amylomaltase. PMID:8018865

  16. alpha'-SiAlON: Phase stability, phase transformations and microstructural evolutions

    NASA Astrophysics Data System (ADS)

    Rosenflanz, Anatoly Zhanovich

    1997-11-01

    Silicon nitride is a prominent member of a ceramic family developed for use in structural applications at ambient and elevated temperatures. It exists in two polymorphic forms, alpha and beta. The predominant form in use today is beta-Sisb3Nsb4. The other form of silicon nitride, alpha-Sisb3Nsb4, is not used even though it is much harder. This is because only beta-Sisb3Nsb4 can be made into a tough and strong ceramic by forming a microstructure that resembles a fiber-reinforced composite. alpha-Sisb3Nsb4, which is unstable at high temperature, can be stabilized by forming solid solutions with Al, O, and interstitial cations, but it always appears with a microstructure of fine, equiaxed grains and has low toughness and strength. Microstructural development of silicon nitride is closely related to phase transformations mediated by a liquid. To help guide the development of new silicon nitride alloys, various aspects of these transformations, and some reverse transformations among them, have been studied. This dissertation sheds light on such issues as the determination of equilibrium phase relations at different temperatures for different compositions, the kinetics of forward and reverse transformations, and the connection of these transformations to the microstructure. Among the outstanding issues that have been resolved by this work are the stability of alphasp'-SiAlON at low temperature and the role of starting powders and rare-earth cations in determining the rate of phase transformations. A new class of alphasp'-SiAlON, which combines the toughness of beta-Sisb3Nsb4 and the hardness of alpha-Sisb3Nsb4, with a whisker-like microstructure, has also been discovered by exploiting the nucleation and growth kinetics of phase transformations.

  17. Nonlinear feedback control for high alpha flight

    NASA Technical Reports Server (NTRS)

    Stalford, Harold

    1990-01-01

    Analytical aerodynamic models are derived from a high alpha 6 DOF wind tunnel model. One detail model requires some interpolation between nonlinear functions of alpha. One analytical model requires no interpolation and as such is a completely continuous model. Flight path optimization is conducted on the basic maneuvers: half-loop, 90 degree pitch-up, and level turn. The optimal control analysis uses the derived analytical model in the equations of motion and is based on both moment and force equations. The maximum principle solution for the half-loop is poststall trajectory performing the half-loop in 13.6 seconds. The agility induced by thrust vectoring capability provided a minimum effect on reducing the maneuver time. By means of thrust vectoring control the 90 degrees pitch-up maneuver can be executed in a small place over a short time interval. The agility capability of thrust vectoring is quite beneficial for pitch-up maneuvers. The level turn results are based currently on only outer layer solutions of singular perturbation. Poststall solutions provide high turn rates but generate higher losses of energy than that of classical sustained solutions.

  18. Mapping High-Velocity H-alpha and Lyman-alpha Emission from Supernova 1987A

    NASA Technical Reports Server (NTRS)

    France, Kevin; McCray, Richard; Fransson, Claes; Larsson, Josefin; Frank, Kari A.; Burrows, David N.; Challis, Peter; Kirshner, Robert P.; Chevalier, Roger A.; Garnavich, Peter; Heng, Kevin; Lawrence, Stephen S.; Lundqvist, Peter; Smith, Nathan; Sonneborn, George

    2015-01-01

    We present new Hubble Space Telescope images of high-velocity H-alpha and Lyman-alpha emission in the outer debris of SN 1987A. The H-alpha images are dominated by emission from hydrogen atoms crossing the reverse shock. For the first time we observe emission from the reverse shock surface well above and below the equatorial ring, suggesting a bipolar or conical structure perpendicular to the ring plane. Using the H-alpha imaging, we measure the mass flux of hydrogen atoms crossing the reverse shock front, in the velocity intervals (-7,500 < V(sub obs) < -2,800 km/s) and (1,000 < V(sub obs) < 7,500 km/s), ?M(sub H) = 1.2 × 10(exp -3) M/ y. We also present the first Lyman-alpha imaging of the whole remnant and new Chandra X-ray observations. Comparing the spatial distribution of the Lyman-alpha and X-ray emission, we observe that the majority of the high-velocity Lyman-alpha emission originates interior to the equatorial ring. The observed Lyman-alpha/H-alpha photon ratio, R(L-alpha/H-alpha) approx. = 17, is significantly higher than the theoretically predicted ratio of approx. = 5 for neutral atoms crossing the reverse shock front. We attribute this excess to Lyman-alpha emission produced by X-ray heating of the outer debris. The spatial orientation of the Lyman-alpha and X-ray emission suggests that X-ray heating of the outer debris is the dominant Lyman-alpha production mechanism in SN 1987A at this phase in its evolution.

  19. Inhibition of NF-kappaB stabilizes gadd45alpha mRNA.

    PubMed

    Zheng, Xue; Zhang, Yadong; Chen, Yu-Quan; Castranova, Vince; Shi, Xianglin; Chen, Fei

    2005-04-01

    Growth arrest- and DNA damage-inducible protein alpha (gadd45alpha) is an important regulator for cell cycle, genomic stability, and cell apoptosis. In the present report, we demonstrated that NF-kappaB inhibition due to Ikkbeta deficiency enhanced the stability of gadd45alpha mNRA. Using embryo fibroblast cells derived from wild type (wt) or Ikkbeta gene knockout (Ikkbeta(-/-)) mice, reverse transcription-polymerase chain reaction revealed a three- to fourfold increase of gadd45alpha mRNA in Ikkbeta(-/-) cells compared with wt cells. The deficiency in Ikkbeta substantially decreased basal NF-kappaB activity and increased accumulation of reactive oxygen species (ROS). However, such deficiency had no effect on the basal expression or activity of Akt, FoxO3a, p53, and c-myc that regulate the transcription of gadd45alpha gene positively or negatively. Analysis of gadd45alpha mRNA stability showed a ROS-dependent increase in the half-life of gadd45alpha mRNA in Ikkbeta(-/-) cells. Immunoprecipitation experiments indicated an increased binding of a RNA stabilizing protein, nucleolin, to gadd45alpha mRNA in Ikkbeta(-/-) cells. The binding of nucleolin to gadd45alpha mRNA could be prevented by the antioxidant, N-acetyl-cysteine. Thus, these data are the first to suggest that inhibition of Ikkbeta-NF-kappaB signaling up-regulates the expression of gadd45alpha mNRA through a post-transcriptional, rather than a transcriptional, mechanism. PMID:15721278

  20. High temperature drilling MUD stabilizer

    SciTech Connect

    Block, J.

    1985-10-15

    Aqueous drilling fluids containing a hydroxy containing alumina component such as AlO(OH) and a polyvinyl alcohol (PVA) reaction product such as an aldehyde reacted PVA are stabilized for use at temperatures as high as 350/sup 0/ F. (177/sup 0/ C.) by adding stabilizer anions such as sulfate, tartrate and citrate to the resulting drilling fluid. The anions can be added as an acid or in the salt form with sodium and potassium salts being preferred. The salts are preferably added in 0.2 to 10% by weight of the drilling fluid. These stabilized drilling fluids can also be used in seawater.

  1. Gyrokinetic Simulations of Enhanced Alpha Transport by De-stabilized Alfvèn Turbulence

    NASA Astrophysics Data System (ADS)

    Bass, E. M.

    2009-11-01

    Alfvèn turbulence, destabilized by fusion-produced α-particles, is expected to greatly enhance transport of these hot fusion products. Previously, the gyrokinetic code GYRO [1] was used to simulate the convective transport of fusion alpha particles by electrostatic (β=0) ITG/TEM turbulence driven at low k (0alpha particles are modeled by a hot Maxwellian (Tα=100,e) superimposed at trace density (0.005< nα/ne<0.025 and a/Lα=4 fixed) on the background plasma. Linear stability studies show two high-frequency modes driven unstable at very long wavelength (0alpha population. A new eigenvalue solver within GYRO shows that the leading modes, identified as the toroidal Alfvèn eigenmode (TAE) and the energetic particle mode (EPM), exhibit hybrid ``drift-Alfvèn" frequency scaling with kθρs and nα. At densities below the Alfvèn linear stability threshold (nα/ne<=0.005), ITG/TEM turbulence dominates nonlinear simulations. In this limit, the transported alpha particles are passive tracers and ion and electron transport agrees well with nα=0 results. Just above the alpha-particle density gradient threshold, Alfvènic (TAE/EPM) drive enhances transport in α-particle and background channels. This trend continues as nα and TAE/EPM microturbulence drive increase. The focus is on conditions for obtaining stationary nonlinearly saturated transport avoiding any subcritical limit on the total beta gradient. 8pt [1] J. Candy and R.E. Waltz, Phys. Rev. Lett. 91, 045001 (2003). [2] C. Estrada-Mila, et al., Phys. Plasmas 13, 112303 (2006).

  2. Effect of chain length on the formation and stability of synthetic alpha-helical coiled coils.

    PubMed

    Su, J Y; Hodges, R S; Kay, C M

    1994-12-27

    A series of polypeptides containing 9, 12, 16, 19, 23, 26, 30, 33, and 35 amino acid residues was designed to investigate the effects of peptide chain length on the formation and stability of two-stranded alpha-helical dimers or coiled coils. These peptides were synthesized by the solid-phase method, purified by reversed-phase high-performance liquid chromatography (RP-HPLC), and characterized by RP-HPLC, amino acid composition analysis, and mass spectrometry. The amphipathic alpha-helical peptides were designed to dimerize by interchain hydrophobic interactions at positions a and d and interchain salt bridges between lysine and glutamic acid residues at positions e and g of the repeating heptad sequence of Glu-Ile-Glu-Ala-Leu-Lys-Ala (g-a-b-c-d-e-f). The ability of these peptides to form alpha-helical structures in the presence and absence of a helix-inducing reagent (trifluoroethanol) was monitored by circular dichroism spectroscopy. The helicity of the peptides increased with increasing chain length in a cooperative manner. A minimum of three heptads corresponding to six helical turns was required for a peptide to adopt the two-stranded alpha-helical coiled coil conformation in aqueous medium. The increased stability of the peptides as a result of an increase in hydrophobic interactions (chain length) was demonstrated by the shift in the transitions of the guanidine hydrochloride (Gdn.HCl) denaturation and thermal unfolding profiles. The concentrations of denaturant (Gdn.HCl) required to achieve 50% denaturation are 3.2, 4.9, 6.9, and 7.5 M for peptides 23r, 26r, 30r, and 33r, respectively, in aqueous medium. However, the effect of a chain length increase on coiled-coil stability was not additive. The melting temperature, Tm, at which 50% of the helicity is lost, increased by 34 degrees C in changing the peptide chain length from 23 to 26; however, that shift was only 14 degrees C when the chain length was increased from 30 to 33 residues. These results are

  3. Structural stability of human alpha-thrombin studied by disulfide reduction and scrambling.

    PubMed

    Rajesh Singh, R; Chang, Jui Yoa

    2003-09-23

    Human alpha-thrombin is a very important plasma serine protease, which is involved in physiologically vital processes like hemostasis, thrombosis, and activation of platelets. Knowledge regarding the structural stability of alpha-thrombin is essential for understanding its biological regulation. Here, we investigated the structural and conformational stability of alpha-thrombin using the techniques of disulfide reduction and disulfide scrambling. alpha-Thrombin is composed of a light A-chain (36 residues) and a heavy B-chain (259 residues) linked covalently by an inter-chain disulfide bond (Cys(1)-Cys(122)). The B-chain is stabilized by three intra-chain disulfide bonds (Cys(42)-Cys(58), Cys(168)-Cys(182), and Cys(191)-Cys(220)) (Chymotrypsinogen nomenclature). Upon reduction with dithiothreitol (DTT), alpha-thrombin unfolded in a 'sequential' manner with sequential reduction of Cys(168)-Cys(182) within the B-chain followed by the inter-chain disulfide, generating two distinct partially reduced intermediates, I-1 and I-2, respectively. Conformational stability of alpha-thrombin was investigated by the technique of disulfide scrambling. alpha-Thrombin denatures by scrambling its native disulfide bonds in the presence of denaturant [urea, guanidine hydrochloride (GdmCl) or guanidine thiocyanate (GdmSCN)] and a thiol initiator. During the process, cleavage of the inter-chain disulfide bond and release of the A-chain from B-chain was the foremost event. The three disulfides in the B-chain subsequently scrambled to form three major isomers (designated as X-Ba, X-Bb, and X-Bc). Complete denaturation of alpha-thrombin was observed at low concentrations of denaturants (0.5 M GdmSCN, 1.5 M GdmCl, or 3 M urea) indicating low conformational stability of the protease. PMID:14499592

  4. High Stability Engine Control (HISTEC)

    NASA Technical Reports Server (NTRS)

    DeLaat, John C.; Southwick, Robert D.; Gallops, George W.

    1996-01-01

    Future aircraft turbine engines, both commercial and military, must be able to successfully accommodate expected increased levels of steady-state and dynamic engine-face distortion. The current approach of incorporating a sufficient component design stall margin to tolerate these increased levels of distortion would significantly reduce performance. The objective of the High Stability Engine Control (HISTEC) program is to design, develop, and flight demonstrate an advanced, high-stability, integrated engine control system that uses measurement-based, real-time estimates of distortion to enhance engine stability. The resulting distortion tolerant control reduces the required design stall margin, with a corresponding increase in performance and decrease in fuel burn. The HISTEC concept, consisting of a Distortion Estimation System and a Stability Management Control, has been designed and developed. The Distortion Estimation System uses a small number of high-response pressure sensors at the engine face to calculate indicators of the type and extent of distortion in real time. The Stability Management Control, through direct control of the fan and compressor pressure ratio, accommodates the distortion by transiently increasing the amount of stall margin available based on information from the Distortion Estimation System. Simulation studies have shown the HISTEC distortion tolerant control is able to successfully estimate and accommodate time-varying distortion. Currently, hardware and software systems necessary for flight demonstration of the HISTEC concept are being designed and developed. The HISTEC concept will be flight tested in early 1997.

  5. Thermal stability of alpha-amylase from Aspergillus oryzae entrapped in polyacrylamide gel.

    PubMed

    Raviyan, Patcharin; Tang, Juming; Rasco, Barbara A

    2003-08-27

    To determine the suitability as a time-temperature indicator for dielectric pasteurization processes, the thermal stability (50-75 degrees C) of Aspergillus oryzae alpha-amylase immobilized in polyacrylamide gel in phosphate buffer, mashed potatoes, and minced shrimp was examined. Changing the cross-linking agent concentration from 3.3 to 5.3% and adding 2% salt did not markedly affect the thermal stability of the immobilized alpha-amylase. Thermal inactivation was first order, and immobilization generally improved the thermal stability of alpha-amylase. z values of the immobilized system in test food systems were 10.2 degrees C (phosphate buffer), 8.45 degrees C (minced shrimp), and 7.78 degrees C (mashed potatoes). PMID:12926898

  6. Thermal stabilization of multimeric proteins: a case study with alpha-globulin.

    PubMed

    Radha, C; Muralidhara, B K; Kumar, P R; Tasneem, R; Prakash, V

    1998-04-01

    Preferential interaction parameters of multisubunit protein, alpha-globulin and monomeric protein human serum albumin (HSA) were determined in different cosolvents using precision densitymetry. The apparent partial specific volumes were determined under both isomolal and isopotential conditions for alpha-globulin in 0.02 M glycine-NaOH buffer at pH 10 and the values were 0.692+/-0.002 and 0.688+/-0.001, ml/g, respectively, at 20.00+/-0.01 degrees C. From the partial specific volume data with cosolvents the preferential interaction parameter (xi3) and other thermodynamic parameters were calculated at different solvent concentrations. The (xi3) values increased with an increase in the solvent concentration up to 30% and reached a maximum with the values of-0.111+/-0.018 g/g and -0.076+/-0.012 g/g in sucrose and sorbitol, respectively. In glycerol the (xi3) values decreased with an increase in solvent concentration. The above data is further supported by thermal denaturation profiles in which the apparent thermal denaturation temperature (apparent Tm) of alpha-globulin shows an increase from 63 degrees C to higher temperatures in the order of sucrose, sorbitol and glycerol. Alpha-globulin showed coagulation due to protein interaction at temperatures above 50 degree C. The apparent Tm of 63 degrees C for control protein was increased significantly up to 75 degrees C in 40% sorbitol with two fold increase in the delta(S) values showing the increased structural stability of alpha-globulin. At high solvent concentration the protein gets dissociated and the resultant monomers are hydrated which was evident by fluorescence data and the difference spectral results with a 6nm red shift in the emission maximum and 2 nm blue shift in UV-absorption maximum arising out of perturbation of aromatic chromophores. The studies were performed both at native pH of 7.9 where the protein is in its oligomeric form and at pH of 10 where it is dissociated form and the results compared. The

  7. Long-Term Stability of Planets in the Alpha Centauri System

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack; Quarles, Billy

    2015-01-01

    The alpha Centauri system is billions of years old, so planets are only expected to be found in regions where their orbits are long-lived. We evaluate the extent of the regions within the alpha Centauri AB star system where small planets are able to orbit for billion-year timescales, and we map the positions in the sky plane where planets on stable orbits about either stellar component may appear. We confirm the qualitative results of Wiegert & Holman (Astron. J. 113, 1445, 1997) regarding the approximate size of the regions of stable orbits of a single planet, which are larger for retrograde orbits relative to the binary than for pro-grade orbits. Additionally, we find that mean motion resonances with the binary orbit leave an imprint on the limits of orbital stability, and the effects of the Lidov-Kozai mechanism are also readily apparent. Overall, orbits of a single planet in the habitable zones near the plane of the binary are stable, whereas high-inclination orbits are short-lived. However, even well within regions where single planets are stable, multiple planet systems must be significantly more widely-spaced than they need to be around an isolated star in order to be long-lived.

  8. High-energy resolution alpha spectrometry using cryogenic detectors.

    PubMed

    Leblanc, E; Coron, N; Leblanc, J; de Marcillac, P; Bouchard, J; Plagnard, J

    2006-01-01

    Applications such as environment monitoring implying alpha emitters activity measurement associated with isotope identification, require high-energy resolution detectors. Conventional silicon detectors are inexpensive therefore widely used, although intrinsically limited in energy resolution. Thermal detection principle of cryogenic detectors introduces a breakthrough in alpha particle measurement. For the first time, spectra with 5.5 keV FWHM energy resolution have been obtained for several external alpha emitting sources using a copper-germanium bolometer specially developed for alpha spectrometry. PMID:16618545

  9. Importance of tetrahydroiso alpha-acids to the microbiological stability of beer.

    PubMed

    Caballero, Isabel; Agut, Montserrat; Armentia, Alicia; Blanco, Carlos A

    2009-01-01

    While beer provides a very stable microbiological environment, a few niche microorganisms are capable of growth in malt, wort, and beer. The production of off-flavors and development of turbidity in the packaged product are due to the growth and metabolic activity of wild yeast, certain lactic acid bacteria (LAB) and anaerobic Gram-negative bacteria. Beer also contains bitter hop compounds, which are toxic to Gram-positive and Gram-negative bacteria, and contribute to preventing the spoilage of this beverage. In the boiling process, the hop alpha-acids (humulones) are isomerized into iso alpha-acids. These products are responsible for the bitter taste of beer, but they also play an essential role in enhancing foam stability. Antibacterial activity of iso alpha-acids and their hydrogenated derivates (rhoiso alpha-acids and tetrahydroiso alpha-acids) in MRS broth and beer have been evaluated against different LAB (Lactobacillus and Pediococcus) for the determination of their beer-stabilizing capabilities. Besides this, we have determined the minimum inhibitory concentration and the bacteriostatic effect of each compound against Pediococcus. We found that tetrahydroiso alpha-acids (added directly to beer during production processes) are the compounds that present the greatest antibacterial activity against the main agents implicated in beer spoilage. PMID:19714985

  10. Alpha-particle effects on high-n instabilities in tokamaks

    SciTech Connect

    Rewoldt, G.

    1988-06-01

    Hot ..cap alpha..-particles and thermalized helium ash particles in tokamaks can have significant effects on high toroidal mode number instabilities such as the trapped-electron drift mode and the kinetically calculated magnetohydrodynamic ballooning mode. In particular, the effects can be stabilizing, destabilizing, or negligible, depending on the parameters involved. In high-temperature tokamaks capable of producing significant numbers of hot ..cap alpha..-particles, the predominant interaction of the mode with the ..cap alpha..-particles is through resonances of various sorts. In turn, the modes can cause significant anomalous transport of the ..cap alpha..-particles and the helium ash. Here, results of comprehensive linear eigenfrequency-eigenfunction calculations are presented for relevant realistic cases to show these effects. 24 refs., 12 figs., 6 tabs.

  11. Effect of polyols on alpha-chymotrypsin thermostability: a mechanistic analysis of the enzyme stabilization.

    PubMed

    Lozano, P; Combes, D; Iborra, J L

    1994-06-15

    The influence of the synthetic substrate (N-acetyl-L-tyrosine ethyl ester) and the different polyols (ethylene glycol, glycerol, erythritol, xylitol and sorbitol) on the thermostability of alpha-chymotrypsin at 60 degrees C have been studied. The results obtained showed an important stabilizing effect in the presence of both additives. In order to describe the kinetics of enzyme stabilization, the experimental results were analyzed by a four-parameters deactivation model with excellent agreement. In all cases, alpha-chymotrypsin exhibited non-first-order deactivation kinetics, corresponding to a two-step unimolecular mechanism, where the main protective effect of polyols was observed in the first-step of the deactivation profile. Thus, the presence of polyols increased the level of activity stabilization (alpha 1), and decreased the first-order deactivation rate constant (k1). Additionally, the experimental results were analyzed as a function of both, the change in the standard free energy of denaturation (delta(delta Gzero)), and a protective effect, defined as the ratio of alpha-chymotrypsin half-lives (with and without polyols), showing in both cases a clear stabilizing effect of these polyhydroxylic cosolvents for the enzyme. The overall protective effect of polyols was also simultaneously related to their concentration and their water-activity depressing power. PMID:7765028

  12. High resolution alpha particle spectrometry through collimation

    NASA Astrophysics Data System (ADS)

    Park, Seunghoon; Kwak, Sung-Woo; Kang, Han-Byeol

    2015-06-01

    Alpha particle spectrometry with collimation is a useful method for identifying nuclear materials among various nuclides. A mesh type collimator reduces the low energy tail and broadened energy distribution by cutting off particles with a low incidence angle. The relation between the resolution and the counting efficiency can be investigated by changing a ratio of the mesh hole diameter and the collimator thickness. Through collimation, a target particle can be distinguished by a PIPS® detector under a mixture of various nuclides.

  13. Proceedings, High-Precision $\\alpha_s$ Measurements from LHC to FCC-ee

    SciTech Connect

    d'Enterria, David; Skands, Peter Z.

    2015-01-01

    This document provides a writeup of all contributions to the workshop on "High precision measurements of $\\alpha_s$: From LHC to FCC-ee" held at CERN, Oct. 12--13, 2015. The workshop explored in depth the latest developments on the determination of the QCD coupling $\\alpha_s$ from 15 methods where high precision measurements are (or will be) available. Those include low-energy observables: (i) lattice QCD, (ii) pion decay factor, (iii) quarkonia and (iv) $\\tau$ decays, (v) soft parton-to-hadron fragmentation functions, as well as high-energy observables: (vi) global fits of parton distribution functions, (vii) hard parton-to-hadron fragmentation functions, (viii) jets in $e^\\pm$p DIS and $\\gamma$-p photoproduction, (ix) photon structure function in $\\gamma$-$\\gamma$, (x) event shapes and (xi) jet cross sections in $e^+e^-$ collisions, (xii) W boson and (xiii) Z boson decays, and (xiv) jets and (xv) top-quark cross sections in proton-(anti)proton collisions. The current status of the theoretical and experimental uncertainties associated to each extraction method, the improvements expected from LHC data in the coming years, and future perspectives achievable in $e^+e^-$ collisions at the Future Circular Collider (FCC-ee) with $\\cal{O}$(1--100 ab$^{-1}$) integrated luminosities yielding 10$^{12}$ Z bosons and jets, and 10$^{8}$ W bosons and $\\tau$ leptons, are thoroughly reviewed. The current uncertainty of the (preliminary) 2015 strong coupling world-average value, $\\alpha_s(m_Z)$ = 0.1177 $\\pm$ 0.0013, is about 1\\%. Some participants believed this may be reduced by a factor of three in the near future by including novel high-precision observables, although this opinion was not universally shared. At the FCC-ee facility, a factor of ten reduction in the $\\alpha_s$ uncertainty should be possible, mostly thanks to the huge Z and W data samples available.

  14. Foam-stabilizing effects and cling formation patterns of iso-alpha-acids and reduced iso-alpha-acids in lager beer.

    PubMed

    Kunimune, Takeshi; Shellhammer, Thomas H

    2008-09-24

    Foam-stabilizing properties and cling formation patterns of iso-alpha-acids and reduced iso-alpha-acids were investigated using an unhopped lager beer. Unhopped beer was dosed with iso-alpha-acid (Iso), rho-iso-alpha-acid (Rho), tetrahydro-iso-alpha-acid (Tetra), and hexahydro-iso-alpha-acid (Hexa), separately, over a range of concentrations from 2 to 10 ppm. A uniform foam was created by Inpack 2000 Flasher Head and was measured by a NIBEM Foam Stability Tester (NIBEM-TPH) followed by a NIBEM Cling Meter (NIBEM-CLM) to determine the relationship between the concentration and NIBEM-30 and the cling formation ability of each compound. The foam-stabilizing power was determined to be Tetra, Hexa, Iso, and Rho from the strongest to weakest. Linear regression models were created using the NIBEM-TPH data set, and on the basis of 95% confidence intervals, the foam stability of Tetra or Hexa became significantly larger than that of Iso when 2.4 or 4.2 ppm of Tetra or Hexa was used as a replacement for Iso, respectively. Cling formation patterns could be categorized into three groups: "ring", "mesh", and "powdery". The control beer had the lowest foam stability and did not yield any foam cling. PMID:18729457

  15. High stability buffered phase comparator

    NASA Technical Reports Server (NTRS)

    Adams, W. A.; Reinhardt, V. S. (Inventor)

    1984-01-01

    A low noise RF signal phase comparator comprised of two high stability driver buffer amplifiers driving a double balanced mixer which operate to generate a beat frequency between the two RF input signals coupled to the amplifiers from the RF sources is described. The beat frequency output from the mixer is applied to a low noise zero crossing detector which is the phase difference between the two RF inputs. Temperature stability is provided by mounting the amplifiers and mixer on a common circuit board with the active circuit elements located on one side of a circuit board and the passive circuit elements located on the opposite side. A common heat sink is located adjacent the circuit board. The active circuit elements are embedded into the bores of the heat sink which slows the effect of ambient temperature changes and reduces the temperature gradients between the active circuit elements, thus improving the cancellation of temperature effects. The two amplifiers include individual voltage regulators, which increases RF isolation.

  16. Nonlinear stability and control study of highly maneuverable high performance aircraft

    NASA Technical Reports Server (NTRS)

    Mohler, R. R.

    1991-01-01

    The purpose was to develop and apply new nonlinear system methodologies to the stability analysis and adaptive control of high angle of attack (alpha) aircraft such as the F-18. Considerable progress is documented on nonlinear adaptive control and associated model development, identification, and simulation. The analysis considered linear and nonlinear, longitudinal, high alpha aircraft dynamics with varying degrees of approximation dependent on the purpose. In all cases, angle of attack or pitch rate was controlled primarily by a horizontal stabilizer. In most cases studied, a linear adaptive controller provided sufficient stability. However, it has been demonstrated by simulation of a simplified nonlinear model that certain large rapid maneuvers were not readily stabilized by the investigated linear adaptive control, but were controlled instead by means of a nonlinear time-series based adaptive control.

  17. Alpha high-power chemical laser program

    NASA Astrophysics Data System (ADS)

    Cordi, Anthony J.; Lurie, Henry; Callahan, David W.; Thomson, Matthew

    1993-06-01

    Alpha is a megawatt-class ground demonstration of a hydrogen fluoride, continuous wave, space-based chemical laser. The laser operates in the infrared at 2.8 microns. The basic device consists of a cylindrical combustion chamber that exhausts radially outward through circumferential nozzles into an annular lasing area. An annular ring resonator is used to extract the laser energy from this area. Technical firsts include: (1) use of aluminum combustion chamber/nozzle ring modules, (2) diamond turned, water-cooled optics made of molybdenum for low thermal distortion with good heat transfer, (3) use of uncooled silicon mirrors in a megawatt-class laser system, (4) an optical bench made of aluminum honeycomb, and (5) active controls to adjust alignment of selected mirrors and the optical bench.

  18. Independent movement, dimerization and stability of tandem repeats of chicken brain alpha-spectrin

    SciTech Connect

    Kusunoki, H.; Minasov, G.; Macdonald, R.I.; Mondragon, A.

    2010-03-08

    Previous X-ray crystal structures have shown that linkers of five amino acid residues connecting pairs of chicken brain {alpha}-spectrin and human erythroid {beta}-spectrin repeats can undergo bending without losing their {alpha}-helical structure. To test whether bending at one linker can influence bending at an adjacent linker, the structures of two and three repeat fragments of chicken brain {alpha}-spectrin have been determined by X-ray crystallography. The structure of the three-repeat fragment clearly shows that bending at one linker can occur independently of bending at an adjacent linker. This observation increases the possible trajectories of modeled chains of spectrin repeats. Furthermore, the three-repeat molecule crystallized as an antiparallel dimer with a significantly smaller buried interfacial area than that of {alpha}-actinin, a spectrin-related molecule, but large enough and of a type indicating biological specificity. Comparison of the structures of the spectrin and {alpha}-actinin dimers supports weak association of the former, which could not be detected by analytical ultracentrifugation, versus strong association of the latter, which has been observed by others. To correlate features of the structure with solution properties and to test a previous model of stable spectrin and dystrophin repeats, the number of inter-helical interactions in each repeat of several spectrin structures were counted and compared to their thermal stabilities. Inter-helical interactions, but not all interactions, increased in parallel with measured thermal stabilities of each repeat and in agreement with the thermal stabilities of two and three repeats and also partial repeats of spectrin.

  19. Placental Alpha Hemoglobin Stabilizing Protein (AHSP) and recurrent miscarriage

    PubMed Central

    Emanuelli, Monica; Cecati, Monia; Sartini, Davide; Stortoni, Piergiorgio; Corradetti, Alessandra; Giannubilo, Stefano R.; Turi, Angelo

    2008-01-01

    AHSP inhibits cellular production of the reactive oxygen species. Reduced AHSP indicates reduced protection against oxidative stressors. Our objective was to investigate AHSP levels in recurrent miscarriage (RM). Trophoblast was collected from women of 10 weeks gestation: voluntary abortion controls (VA, n = 10); spontaneous first miscarriage with subsequent normal pregnancy (SMSN, n = 15) or with subsequent miscarriage (SMSM, n = 5); RM previously investigated (RMPS, n = 5) or not previously investigated (RM, n = 5). AHSP mRNA and protein were determined using real-time quantitative polymerase chain reaction (PCR) and Western blot, respectively. One-way ANOVA was performed to assess statistical significance (p < 0.05). ahsp mRNA levels were maximally reduced in RM and RMPS (8.0 × 10−6 ± 1.3 and 8.1 × 10−6 ± 0.7, respectively) compared with SMSN and VA (16.1 × 10−6 ± 2.3 and 26.1 × 10−6 ± 2.7, respectively). SMSM showed levels significantly reduced as well (9.0 × 10−6 ± 2.3). In RM, a reduced defense from oxidative stressors is evident at first miscarriage, identifying women at high risk for subsequent eventful pregnancy. Reduced AHSP may identify women at risk of experiencing further miscarriages. PMID:18704762

  20. Orbital Eccentricity and the Stability of Planets in the Alpha Centauri System

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack

    2016-01-01

    Planets on initially circular orbits are typically more dynamically stable than planets initially having nonzero eccentricities. However, the presence of a major perturber that forces periodic oscillations of planetary eccentricity can alter this situation. We investigate the dependance of system lifetime on initial eccentricity for planets orbiting one star within the alpha Centauri system. Our results show that initial conditions chosen to minimize free eccentricity can substantially increase stability compared to planets on circular orbits.

  1. Orbital Eccentricity and the Stability of Planets in the Alpha Centauri System

    NASA Astrophysics Data System (ADS)

    Lissauer, Jack J.; Quarles, Billy L.

    2016-05-01

    Planets on initially circular orbits are typically more dynamically stable than planets initially having nonzero eccentricities. However, the presence of a major perturber that forces periodic oscillations of planetary eccentricity can alter this situation. We investigate the dependance of system lifetime on initial eccentricity for planets orbiting one star within the alpha Centauri system. Our results show that initial conditions chosen to minimize free eccentricity can substantially increase stability compared to planets on circular orbits.

  2. Stability of {sup 248–254}Cf isotopes against alpha and cluster radioactivity

    SciTech Connect

    Santhosh, K.P. Biju, R.K.

    2013-07-15

    Stability of {sup 248–254}Cf nuclei against alpha and cluster emissions is studied within our Coulomb and proximity potential model (CPPM). It is found that these nuclei are stable against light clusters (except alpha particles) and unstable against heavy cluster (A{sub 2}≥40) emissions. For heavy cluster emissions the daughter nuclei lead to doubly magic {sup 208}Pb or the neighbouring one. The effects of quadrupole and hexadecapole deformations of parent nuclei, daughter nuclei and emitted cluster on half lives are also studied. The computed alpha decay half life values (including quadrupole deformation β{sub 2}) are in close agreement with experimental data. Inclusion of quadrupole deformation reduces the height and width of the barrier (increases the barrier penetrability) and hence half life decreases. -- Highlights: •{sup 248–254}Cf parents are stable against light clusters (except alpha particles) and are unstable against heavy clusters ({sup 46}Ar, {sup 48,50}Ca etc.). •For the case of heavy cluster emissions the daughter nuclei are doubly magic {sup 208}Pb or neighbouring one. •The alpha decay half lives are in agreement with experimental data. •The cluster decay half lives decrease with the inclusion of quadrupole deformation.

  3. F-18 high alpha research vehicle: Lessons learned

    NASA Technical Reports Server (NTRS)

    Bowers, Albion H.; Regenie, Victoria A.; Flick, Bradley C.

    1994-01-01

    The F-18 High Alpha Research Vehicle has proven to be a useful research tool with many unique capabilities. Many of these capabilities are to assist in characterizing flight at high angles of attack, while some provide significant research in their own right. Of these, the thrust vectoring system, the unique ability to rapidly reprogram flight controls, the reprogrammable mission computer, and a reprogrammable onboard excitation system have allowed an increased utility and versatility of the research being conducted. Because of this multifaceted approach to research in the high angle of attack regime, the capabilities of the F-18 High Alpha Research Vehicle were designed to cover as many high alpha technology bases as the program would allow. These areas include aerodynamics, controls, handling qualities, and propulsion.

  4. The relationship between structural stability and electrochemical performance of multi-element doped alpha nickel hydroxide

    NASA Astrophysics Data System (ADS)

    Miao, Chengcheng; Zhu, Yanjuan; Huang, Liangguo; Zhao, Tengqi

    2015-01-01

    The multi-element doped alpha nickel hydroxide has been prepared by supersonic co-precipitation method. Three kinds of samples A, B and C are prepared by chemically coprecipitating Ni/Al, Ni/Al/Mn and Ni/Al/Mn/Yb, respectively. Inductively coupled plasma atomic emission spectroscopy (ICP-AES), Particle size distribution (PSD) measurement, X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) are used to characterize the physical properties of the synthesized α-Ni(OH)2 samples, such as chemical composition, morphology, structural stability of the crystal. The results show that all samples are nano-sized materials and the interlayer spacing becomes larger and the structural stability becomes better with the increase of doped elements and doped ratio. The prepared alpha nickel hydroxide samples are added into micro-sized beta nickel hydroxide to form biphase electrode materials for Ni-MH battery. The electrochemical characterization of the biphase electrodes, including cyclic voltammetry (CV) and charge/discharge test, are also performed. The results demonstrate that the biphase electrode with sample C exhibits better electrochemical reversibility and cyclic stability, higher charge efficient and discharge potential, larger proton diffusion coefficient (5.81 × 10-12 cm2 s-1) and discharge capacity (309.0 mAh g-1). Hence, it indicates that all doped elements can produce the synergic effect and further improve the electrochemical properties of the alpha nickel hydroxide.

  5. An amphipathic alpha-helical peptide from apolipoprotein A1 stabilizes protein polymer vesicles.

    PubMed

    Pastuszka, Martha K; Wang, Xiangdong; Lock, Lye Lin; Janib, Siti Mohd; Cui, Honggang; DeLeve, Laurie D; MacKay, J Andrew

    2014-10-10

    L4F, an alpha helical peptide inspired by the lipid-binding domain of the ApoA1 protein, has potential applications in the reduction of inflammation involved with cardiovascular disease as well as an antioxidant effect that inhibits liver fibrosis. In addition to its biological activity, amphipathic peptides such as L4F are likely candidates to direct the molecular assembly of peptide nanostructures. Here we describe the stabilization of the amphipathic L4F peptide through fusion to a high molecular weight protein polymer. Comprised of multiple pentameric repeats, elastin-like polypeptides (ELPs) are biodegradable protein polymers inspired from the human gene for tropoelastin. Dynamic light scattering confirmed that the fusion peptide forms nanoparticles with a hydrodynamic radius of approximately 50nm, which is unexpectedly above that observed for the free ELP (~5.1nm). To further investigate their morphology, conventional and cryogenic transmission electron microscopy were used to reveal that they are unilamellar vesicles. On average, these vesicles are 49nm in radius with lamellae 8nm in thickness. To evaluate their therapeutic potential, the L4F nanoparticles were incubated with hepatic stellate cells. Stellate cell activation leads to hepatic fibrosis; furthermore, their activation is suppressed by anti-oxidant activity of ApoA1 mimetic peptides. Consistent with this observation, L4F nanoparticles were found to suppress hepatic stellate cell activation in vitro. To evaluate the in vivo potential for these nanostructures, their plasma pharmacokinetics were evaluated in rats. Despite the assembly of nanostructures, both free L4F and L4F nanoparticles exhibited similar half-lives of approximately 1h in plasma. This is the first study reporting the stabilization of peptide-based vesicles using ApoA1 mimetic peptides fused to a protein polymer; furthermore, this platform for peptide-vesicle assembly may have utility in the design of biodegradable nanostructures

  6. ''Pulling'' Nanoparticles into Water: Phase Transfer of Oleic Acid Stabilized Monodisperse Nanoparticles into Aqueous Solutions of alpha-Cyclodextrin

    SciTech Connect

    Wang, Y.; Wong, J.F.; Teng, X.; Lin, X.Z.; Yang, H.

    2003-10-18

    (B204)This paper describes a general method to drastically improve the disparity of oleic acid stabilized nanoparticles in aqueous solutions. We use oleic acid stabilized monodisperse nanoparticles of iron oxides and silver as model systems, and have modified the surface properties of these nanoparticles through the formation of an inclusion complex between surface-bound surfactant molecules and alpha-cyclodextrin (alpha-CD). After the modification, the nanoparticles of both iron oxide and Ag can transfer from hydrophobic solvents, such as hexane, to alpha-CD aqueous phase. The efficiency of the phase transfer to the aqueous solutions depend son the initial alpha-CD concentration. The alpha-CD/oleic acid complex stabilized nanoparticles can be stable for long periods of time in aqueous phase under ambient atmospheric conditions. Transmission electron microscopy (TME), ultraviolet-visible (UV-vis) spectroscopy, Fourier transform-infrared (FT-IR) spectroscopy, and colorimetric methods have been used in the characterization of these nanoparticles.

  7. Fourth High Alpha Conference, volume 3

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Thie goal of this conference was to focus on the flight validation of high-angle-of-attack technologies and provide an in-depth review of the latest high-angle-of-attack activities. Areas covered include: (1) high-angle-of-attack aerodynamics; (2) propulsion and inlet dynamics; (3) thrust vectoring; (4) control laws and handling qualities; (5) tactical utility; and (6) forebody controls.

  8. {alpha} decay of high-spin isomers in superheavy nuclei

    SciTech Connect

    Delion, D. S.; Liotta, R. J.; Wyss, R.

    2007-10-15

    Hindrance factors corresponding to {alpha} decay from two quasiparticle isomeric high K states are evaluated in superheavy nuclei. We found that the hindrance factors are very sensitive to the deformations and, therefore, they may constitute a powerful tool to extract spectroscopic information in these nuclei. The hindrance factors turn out to be very large, specially for nonaligned configurations. This indicates that if one of such states is reached the parent nucleus may become isomeric. It is also possible that {alpha} decay may not proceed through ground state to ground state chains but rather through excited states.

  9. High beta and second stability region transport and stability analysis

    SciTech Connect

    Hughes, M.H.; Phillps, M.W.; Todd, A.M.M.; Krishnaswami, J.; Hartley, R.

    1992-09-01

    This report describes ideal and resistive studies of high-beta plasmas and of the second stability region. Emphasis is focused on supershot'' plasmas in TFIR where MHD instabilities are frequently observed and which spoil their confinement properties. Substantial results are described from the analysis of these high beta poloidal plasmas. During these studies, initial pressure and safety factor profiles were obtained from the TRANSP code, which is used extensively to analyze experimental data. Resistive MBD stability studies of supershot equilibria show that finite pressure stabilization of tearing modes is very strong in these high {beta}p plasmas. This has prompted a detailed re-examination of linear tearing mode theory in which we participated in collaboration with Columbia University and General Atomics. This finite pressure effect is shown to be highly sensitive to small scale details of the pressure profile. Even when an ad hoc method of removing this stabilizing mechanism is implemented, however, it is shown that there is only superficial agreement between resistive MBD stability computation and the experimental data. While the mode structures observed experimentally can be found computationally, there is no convincing correlation with the experimental observations when the computed results are compared with a large set of supershot data. We also describe both the ideal and resistive stability properties of TFIR equilibria near the transition to the second region. It is shown that the highest {beta} plasmas, although stable to infinite-n ideal ballooning modes, can be unstable to the so called infernal'' modes associated with small shear. The sensitivity of these results to the assumed pressure and current density profiles is discussed. Finally, we describe results from two collaborative studies with PPPL. The first involves exploratory studies of the role of the 1/1 mode in tokamaks and, secondly, a study of sawtooth stabilization using ICRF.

  10. Nonlinear stability and control study of highly maneuverable high performance aircraft, phase 2

    NASA Technical Reports Server (NTRS)

    Mohler, R. R.

    1992-01-01

    This research should lead to the development of new nonlinear methodologies for the adaptive control and stability analysis of high angle-of-attack aircraft such as the F18 (HARV). The emphasis has been on nonlinear adaptive control, but associated model development, system identification, stability analysis and simulation is performed in some detail as well. Various models under investigation for different purposes are summarized in tabular form. Models and simulation for the longitudinal dynamics have been developed for all types except the nonlinear ordinary differential equation model. Briefly, studies completed indicate that nonlinear adaptive control can outperform linear adaptive control for rapid maneuvers with large changes in alpha. The transient responses are compared where the desired alpha varies from 5 degrees to 60 degrees to 30 degrees and back to 5 degrees in all about 16 sec. Here, the horizontal stabilator is the only control used with an assumed first-order linear actuator with a 1/30 sec time constant.

  11. Wake Measurements at alpha ventus - Dependency on Stability and Turbulence Intensity

    NASA Astrophysics Data System (ADS)

    Westerhellweg, Annette; Cañadillas, Beatriz; Kinder, Friederike; Neumann, Tom

    2014-12-01

    Wind and power deficit in the wake are assessed for the offshore wind farm Alpha Ventus. Operational data are evaluated for the power deficit in the wake of a single wind turbine and in a row of wind turbines. The wake of a single wind turbine is described by the maximum power deficit and expansion width of the wake. The impact of atmospheric stability in respect to vertical wind shear and turbulence intensity is assessed showing that wake effects are more pronounced under stable conditions.

  12. Sterically stabilized liposomes as a carrier for alpha-emitting radium and actinium radionuclides.

    PubMed

    Henriksen, Gjermund; Schoultz, B W; Michaelsen, T E; Bruland, Ø S; Larsen, R H

    2004-05-01

    The alpha-particle emitting radionuclides (223)Ra (t(1/2) = 11.4 d), (224)Ra (t(1/2) = 3.6 d), and (225)Ac(t(1/2) = 10.0 d) may have a broad application in targeted radiotherapy provided that they could be linked to vehicles with tumor affinity. The potential usefulness of liposomes as carriers was studied in the present work. Radium and actinium radionuclides could be loaded in good yields into sterically stabilized liposomes. Subsequent coating of the liposomes with a folate-F(ab')(2) construct yielded a product with affinity towards tumor cells expressing folate receptors. Radionuclide loaded liposomes showed excellent stability in serum in vitro. PMID:15093814

  13. High Alpha Technology Program (HATP) ground test to flight comparisons

    NASA Technical Reports Server (NTRS)

    Hall, R. M.; Banks, D. W.; Fisher, David F.; Ghaffari, F.; Murri, D. G.; Ross, J. C.; Lanser, Wendy R.

    1994-01-01

    This status paper reviews the experimental ground test program of the High Alpha Technology Program (HATP). The reasons for conducting this ground test program had their origins during the 1970's when several difficulties were experienced during the development programs of both the F-18 and F-16. A careful assessment of ground test to flight correlations appeared to be important for reestablishing a high degree of confidence in our ground test methodology. The current paper will then focus on one aspect of the HATP program that is intended to improve the correlation between ground test and flight, high-alpha gritting. The importance of this work arises from the sensitivity of configurations with smooth-sided forebodies to Reynolds number. After giving examples of the effects of Reynolds number, the paper will highlight efforts at forebody gritting. Finally, the paper will conclude by summarizing the charter of the HATP Experimental Aerodynamics Working Group and future experimental testing plans.

  14. The Role of Alpha-Hemoglobin Stabilizing Protein in Redox Chemistry, Denaturation, and Hemoglobin Assembly

    PubMed Central

    Mollan, Todd L.; Yu, Xiang; Weiss, Mitchell J.

    2010-01-01

    Abstract Hemoglobin biosynthesis in erythrocyte precursors involves several steps. The correct ratios and concentrations of normal alpha (α) and beta (β) globin proteins must be expressed; apoproteins must be folded correctly; heme must be synthesized and incorporated into these globins rapidly; and the individual α and β subunits must be rapidly and correctly assembled into heterotetramers. These events occur on a large scale in vivo, and dysregulation causes serious clinical disorders such as thalassemia syndromes. Recent work has implicated a conserved erythroid protein known as Alpha-Hemoglobin Stabilizing Protein (AHSP) as a participant in these events. Current evidence suggests that AHSP enhances α subunit stability and diminishes its participation in harmful redox chemistry. There is also evidence that AHSP facilitates one or more early-stage post-translational hemoglobin biosynthetic events. In this review, recent experimental results are discussed in light of several current models describing globin subunit folding, heme uptake, assembly, and denaturation during hemoglobin synthesis. Particular attention is devoted to molecular interactions with AHSP that relate to α chain oxidation and the ability of α chains to associate with partner β chains. Antioxid. Redox Signal. 12, 219–232. PMID:19659437

  15. Thermal stability of alpha-amylase from malted jowar (Sorghum bicolor).

    PubMed

    Kumar, R Siva Sai; Singh, Sridevi Annapurna; Rao, A G Appu

    2005-08-24

    Malted cereals are rich sources of alpha-amylase, which catalyzes the random hydrolysis of internal alpha-(1-4)-glycosidic bonds of starch, leading to liquefaction. Amylases play a role in the predigestion of starch, leading to a reduction in the water absorption capacity of the cereal. Among the three cereal amylases (barley, ragi, and jowar), jowar amylase is found to be the most thermostable. The major amylase from malted jowar, a 47 kDa alpha-amylase, purified to homogeneity, is rich in beta structure ( approximately 60%) like other cereal amylases. T(m), the midpoint of thermal inactivation, is found to be 69.6 +/- 0.3 degrees C. Thermal inactivation is found to follow first-order kinetics at pH 4.8, the pH optimum of the enzyme. Activation energy, E(a), is found to be 45.3 +/- 0.2 kcal mol(-)(1). The activation enthalpy (DeltaH), entropy (DeltaS*), and free energy change (DeltaG) are calculated to be 44.6 +/- 0.2 kcal mol(-)(1), 57.1 +/- 0.3 cal mol(-)(1) K(-)(1), and 25.2 +/- 0.2 kcal mol(-)(1), respectively. The thermal stability of the enzyme in the presence of the commonly used food additives NaCl and sucrose has been studied. T(m) is found to decrease to 66.3 +/- 0.3, 58.1 +/- 0.2, and 48.1 +/- 0.5 degrees C, corresponding to the presence of 0.1, 0.5, and 1 M NaCl, respectively. Sucrose acts as a stabilizer; the T(m) value is found to be 77.3 +/- 0.3 degrees C compared to 69.6 +/- 0.3 degrees C in the control. PMID:16104815

  16. High acyl gellan as an emulsion stabilizer.

    PubMed

    Vilela, Joice Aline Pires; da Cunha, Rosiane Lopes

    2016-03-30

    High acyl gellan (0.01-0.2% w/w) was used as stabilizer in oil in water emulsions containing 30% (w/w) of sunflower oil and prepared under different process conditions. Stable emulsions to phase separation could be obtained using high acyl gellan (HA) content above 0.05% (w/w), while low acyl gellan (LA) prepared at the same conditions could not stabilize emulsions. Emulsions properties depended on the process used to mix the oil and gellan dispersion since high pressure homogenization favored stabilization while very high energy density applied by ultrasound led to systems destabilization. Emulsions prepared using high pressure homogenization showed zeta potential values ranging from -50 up to -59 mV, suggesting that electrostatic repulsion could be contributing to the systems stability. Rheological properties of continuous phase were also responsible for emulsions stabilization, since HA gellan dispersions showed high viscosity and gel-like behavior. The high viscosity of the continuous phase could be associated to the presence of high acyl gellan microgels/aggregates. Disentanglement of these aggregates performed by ultrasound strongly decreased the viscosity and consequently affected the emulsions behavior, reducing the stability to phase separation. PMID:26794954

  17. High Reynolds Number Thermal Stability Experiments

    NASA Technical Reports Server (NTRS)

    Emens, Jessica M.; Brown, Sarah P.; Frederick Robert A., Jr.; Wood, A. John

    2004-01-01

    This work represents preliminary thermal stability results for liquid hydrocarbon fuels. High Reynolds Number Thermal Stability experiments with Jet A and RP-1 resulted in a quantitative measurement of the thermal stability. Each fuel flowed through a heated capillary tube that held the outlet temperature at 290 C. An optical pyrometer measured the surface temperature of the tube at 12 locations as a function of time. The High Reynolds Number Thermal Stability number was then determined using standards published by the American Society for Testing and Materials. The results for Jet A showed lower thermal stability than similar tests conducted at another facility. The RP-1 results are the first reported using this technique. Because the temperature rise on the capillary tube during testing for the RP-1 fuels was not significant, a new standard for the testing conditions should be developed for these types of fuels.

  18. Structural phase stability in group IV metals under static high pressure

    SciTech Connect

    Velisavljevic, Nenad; Chesnut, Garry N; Dattelbaum, Dana M; Vohra, Yogesh K; Stemshorn, Andrew

    2009-01-01

    In group IV metals (Ti, Zr, and Hf) room temperature compression leads to a martensitic transformation from a ductile {alpha} to a brittle {omega} phase. {alpha} {yields} {omega} phase boundary decreases to lower pressure at high temperature and can limit the use of group IV metals in industrial applications. There is a large discrepancy in the transition pressure reported in literature, with some of the variation attributed to experimental conditions (i.e. hydrostatic vs. non-hydrostatic). Shear deformation in non-hydrostatic experiments drives {alpha} {yields} {omega} transition and decreases transition pressure. Impurities can also aid or suppress {alpha} {yields} {omega} transition. By performing x-ray diffraction experiments on samples in a diamond anvil cell we show that interstitial impurities, such as C, N, and O can obstruct {alpha} {yields} {omega} transition and stabilize {alpha} phase to higher pressure. We also show that reduction in grain size can also influence {alpha} {yields} {omega} phase boundary and help stabilize {alpha} phase to higher pressure under non-hydrostatic conditions.

  19. Stability study of full-length antibody (anti-TNF alpha) loaded PLGA microspheres.

    PubMed

    Marquette, S; Peerboom, C; Yates, A; Denis, L; Langer, I; Amighi, K; Goole, J

    2014-08-15

    Antibodies (Abs) require the development of stable formulations and specific delivery strategies given their susceptibility to a variety of physical and chemical degradation pathways. In this study, the encapsulation of an antibody into polylactide-co-glycolide (PLGA) based microspheres was explored to obtain a controlled-release of the incorporated drug. In order to avoid stability issues, a solid-in-oil-in-water (s/o/w) method was preferred. The solid phase was made of anti-TNF alpha monoclonal antibody (MAb) spray-dried microparticles, and the PLGA microspheres were produced using two different polymers (i.e., Resomer(®) RG505 and Resomer(®) RG755S). The stability of the MAb incorporated into the microspheres was investigated under three conditions (5 ± 3°C, 25 ± 2°C/60% RH and 40 ± 2°C/75% RH) for 12 weeks. During this stability study, it was demonstrated that the MAb loaded PLGA microspheres were stable when stored at 5 ± 3°C and that the Resomer(®) RG755S, composed of 75%(w/w) lactic acid as PLGA, was preferred to preserve the stability of the system. Storage at temperatures higher than 5°C led to antibody stability issues such as aggregation, fragmentation and loss of activity. The release profiles were also altered. Physical ageing of the system associated with changes in the glass transition temperature and enthalpy of relaxation was noticed during the storage of the MAb loaded PLGA microspheres. PMID:24792974

  20. Excitation of high-n toroidicity-induced shear Alfven eigenmodes by energetic particles and fusion alpha particles in tokamaks

    SciTech Connect

    Fu, G.Y.; Cheng, C.Z.

    1992-07-01

    The stability of high-n toroidicity-induced shear Alfven eigenmodes (TAE) in the presence of fusion alpha particles or energetic ions in tokamaks is investigated. The TAE modes are discrete in nature and thus can easily tap the free energy associated with energetic particle pressure gradient through wave particle resonant interaction. A quadratic form is derived for the high-n TAE modes using gyro-kinetic equation. The kinetic effects of energetic particles are calculated perturbatively using the ideal MHD solution as the lowest order eigenfunction. The finite Larmor radius (FLR) effects and the finite drift orbit width (FDW) effects are included for both circulating and trapped energetic particles. It is shown that, for circulating particles, FLR and FDW effects have two opposite influences on the stability of the high-n TAE modes. First, they have the usual stabilizing effects by reducing the wave particle interaction strength. Second, they also have destabilizing effects by allowing more particles to resonate with the TAE modes. It is found that the growth rate induced by the circulating alpha particles increase linearly with toroidal mode number n for small {kappa}{sub {theta}}{rho}{sub {alpha}}, and decreases as 1/n for {kappa}{sub {theta}}{rho}{sub {alpha}} {much_gt} 1. The maximum growth rate is obtained at {kappa}{sub {theta}}{rho}{sub {alpha}} on the order of unity and is nearly constant for the range of 0.7 < {upsilon}{sub {alpha}}/{upsilon}{sub A} < 2.5. On the other hand, the trapped particle response is dominated by the precessional drift resonance. The bounce resonant contribution is negligible. The growth rate peaks sharply at the value of {kappa}{sub {theta}}{rho}{sub {alpha}} such that the precessional drift resonance occurs for the most energetic trapped particles. The maximum growth rate due to the energetic trapped particles is comparable to that of circulating particles.

  1. Excitation of high-n toroidicity-induced shear Alfven eigenmodes by energetic particles and fusion alpha particles in tokamaks

    SciTech Connect

    Fu, G.Y.; Cheng, C.Z.

    1992-07-01

    The stability of high-n toroidicity-induced shear Alfven eigenmodes (TAE) in the presence of fusion alpha particles or energetic ions in tokamaks is investigated. The TAE modes are discrete in nature and thus can easily tap the free energy associated with energetic particle pressure gradient through wave particle resonant interaction. A quadratic form is derived for the high-n TAE modes using gyro-kinetic equation. The kinetic effects of energetic particles are calculated perturbatively using the ideal MHD solution as the lowest order eigenfunction. The finite Larmor radius (FLR) effects and the finite drift orbit width (FDW) effects are included for both circulating and trapped energetic particles. It is shown that, for circulating particles, FLR and FDW effects have two opposite influences on the stability of the high-n TAE modes. First, they have the usual stabilizing effects by reducing the wave particle interaction strength. Second, they also have destabilizing effects by allowing more particles to resonate with the TAE modes. It is found that the growth rate induced by the circulating alpha particles increase linearly with toroidal mode number n for small {kappa}{sub {theta}}{rho}{sub {alpha}}, and decreases as 1/n for {kappa}{sub {theta}}{rho}{sub {alpha}} {much gt} 1. The maximum growth rate is obtained at {kappa}{sub {theta}}{rho}{sub {alpha}} on the order of unity and is nearly constant for the range of 0.7 < {upsilon}{sub {alpha}}/{upsilon}{sub A} < 2.5. On the other hand, the trapped particle response is dominated by the precessional drift resonance. The bounce resonant contribution is negligible. The growth rate peaks sharply at the value of {kappa}{sub {theta}}{rho}{sub {alpha}} such that the precessional drift resonance occurs for the most energetic trapped particles. The maximum growth rate due to the energetic trapped particles is comparable to that of circulating particles.

  2. Stability and Change in High School Grades

    ERIC Educational Resources Information Center

    Guskey, Thomas R.

    2011-01-01

    This study investigated the stability of students' grades in high school courses during the academic year. Records of over 8,000 high school students from five large southeastern high schools were analyzed to determine the relationship between the first achievement grade students were assigned during an academic term and their final course grades.…

  3. Lyman-alpha emission from the Lyman-alpha forest. [in high red shift quasar spectra due to molecular clouds

    NASA Technical Reports Server (NTRS)

    Hogan, Craig J.; Weymann, Ray J.

    1987-01-01

    It is suggested that high-dispersion long-slit spectra or very narrow-band etalon images of 'blank' sky could reveal patches of Ly-alpha line emission from the population of clouds whose absorption produces the 'Ly-alpha forest' in QSO spectra. A nonobservation can put limits on the ionizing background at high redshift which are better than those obtainable by direct measurements of background light.

  4. X-29 High Alpha Test in the National Transonic Facility

    NASA Technical Reports Server (NTRS)

    Underwood, Pamela J.; Owens, Lewis R.; Wahls, Richard A.; Williams, Susan

    2003-01-01

    This paper describes the X-29A research program at the National Transonic Facility. This wind tunnel test leveraged the X-29A high alpha flight test program by enabling ground-to-flight correlation studies with an emphasis on Reynolds number effects. The background and objectives of this test program, as well as the comparison of high Reynolds number wind tunnel data to X-29A flight test data are presented. The effects of Reynolds number on the forebody pressures at high angles of attack are also presented. The purpose of this paper is to document this test and serve as a reference for future ground-to-flight correlation studies, and high angle-of-attack investigations. Good ground-to-flight correlations were observed for angles of attack up to 50 deg, and Reynolds number effects were also observed.

  5. Evaluation of miniature vacuum ultraviolet lamps for stability and operating characteristics, Lyman-Alpha task

    NASA Technical Reports Server (NTRS)

    Hurd, W. A.

    1985-01-01

    Modifications required to change the near ultraviolet source in the Optical Contamination Monitor to a source with output at or near the Lyman-Alpha hydrogen line are discussed. The effort consisted of selecting, acquiring and testing candidate miniature ultraviolet lamps with significant output in or near 121.6 nm. The effort also included selection of a miniature dc high-voltage power supply capable of operating the lamp. The power supply was required to operate from available primary power supplied by the Optical Effect Module (DEM) and it should be flight qualified or have the ability to be qualified by the user.

  6. High-activity barley alpha-amylase by directed evolution.

    PubMed

    Wong, Dominic W S; Batt, Sarah B; Lee, Charles C; Robertson, George H

    2004-10-01

    Barley alpha-amylase isozyme 2 was cloned into and constitutively secreted by Saccharomyces cervisiae. The gene coding for the wild-type enzyme was subjected to directed evolution. Libraries of mutants were screened by halo formation on starch agar plates, followed by high-throughput liquid assay using dye-labeled starch as the substrate. The concentration of recombinant enzyme in the culture supernatant was determined by immunodetection, and used for the calculation of specific activity. After three rounds of directed evolution, one mutant (Mu322) showed 1000 times the total activity and 20 times the specific activity of the wild-type enzyme produced by the same yeast expression system. Comparison of the amino acid sequence of this mutant with the wild type revealed five substitutions: Q44H, R303K and F325Y in domain A, and T94A and R128Q in domain B. Two of these mutations. Q44H and R303K, result in amino acids highly conserved in cereal alpha-amylases. R303K and F325Y are located in the raw starch-binding fragment of the enzyme molecule. PMID:15635937

  7. High-performance liquid chromatography of alpha-keto acids in human saliva.

    PubMed

    Tsuchiya, H; Hashizume, I; Tokunaga, T; Tatsumi, M; Takagi, N; Hayashi, T

    1983-01-01

    alpha-Keto acids in human mixed saliva collected without stimulation were analysed by reversed-phase ion-pair high-performance liquid chromatography (HPLC). Several alpha-keto acids were found in saliva and their concentrations were: alpha-ketoglutaric acid (KGA), 221 +/- 142; pyruvic acid (PA), 7490 +/- 5600; alpha-ketoisovaleric acid (KIVA), 61 +/- 23; alpha-ketoisocaproic acid (KICA), 137 +/- 79; alpha-keto-beta-methylvaleric acid (KMVA), 41 +/- 19 nmol/dl (mean +/- SD, n = 40). Their levels proved to be lower than those in plasma, except that of PA. Their concentrations in saliva showed individual variation compared with those in blood. PMID:6581765

  8. Microencapsulation of H. pluvialis oleoresins with different fatty acid composition: Kinetic stability of astaxanthin and alpha-tocopherol.

    PubMed

    Bustamante, Andrés; Masson, Lilia; Velasco, Joaquín; del Valle, José Manuel; Robert, Paz

    2016-01-01

    Haematococcus pluvialis is a natural source of astaxanthin (AX). However, AX loses its natural protection when extracted from this microalga. In this study, a supercritical fluid extract (SFE) of H. pluvialis was obtained and added to oils with different fatty acid compositions (sunflower oil (SO) or high oleic sunflower oil (HOSO)). The oleoresins of H. pluvialis ((SO+SFE) and (HOSO+SFE)) were encapsulated with Capsul by spray drying. The stability of the oleoresins and powders were studied at 40, 50 and 70° C. AX and alpha-tocopherol (AT) degradation followed a zero-order and first-order kinetic model, respectively, for all systems. The encapsulation of oleoresins improved the stability of AX and AT to a greater extent in oleoresins with a monounsaturated fatty acid profile, as shown by the significantly lowest degradation rate constants and longest half-lives. Therefore, the encapsulation of H. pluvialis oleoresins is an alternative to developing a functional ingredient for healthy food design. PMID:26213069

  9. Stabilisation of crosslinked ultra-high molecular weight polyethylene (UHMW-PE)-acetabular components with alpha-tocopherol.

    PubMed

    Wolf, C; Maninger, J; Lederer, K; Frühwirth-Smounig, H; Gamse, T; Marr, R

    2006-12-01

    A stabilisation of crosslinked ultra-high molecular weight polyethylene (UHMW-PE) with alpha-tocopherol (vitamin E) used for endoprostheses can increase its resistance against oxidative degradation remarkably. However, the method used for conventional UHMW-PE of adding alpha-tocopherol to the UHMW-PE powder before processing can not be applied for crosslinked UHMW-PE, since the alpha-tocopherol hinders the crosslinking process, which would be accompanied by a heavy degradation of this vitamin. The alpha-tocopherol has therefore to be added after the crosslinking process. This paper presents two methods for a stabilisation of finished products with alpha-tocopherol. In method 1, UHMW-PE-cubes (20 x 20 x 20 mm3) were stored in pure alpha-tocopherol under inert atmosphere at temperatures from 100 degrees C to 150 degrees C resulting in a high mass fraction of alpha-tocopherol in the edge zones. For further homogenisation, the cubes were stored in inert atmosphere at temperatures from 160 degrees C to 200 degrees C. In method 2, supercritical CO2 was used to incorporate the vitamin into the UHMW-PE. In an autoclave vessel, the cubes were treated with alpha-tocopherol dissolved in supercritical CO2 for several hours at temperatures from 100 degrees C to 170 degrees C. In both cases, the mass fraction of alpha-tocopherol was detected with the help of a FTIR-microscope. Both methods are well suited to stabilise crosslinked UHMW-PE with alpha-tocopherol. A stabilisation of the sensitive edge layer as well as a nearly homogenous distribution with varying alpha-tocopherol content may be realised by varying the process parameters. Using method 2, standard hip cups were stabilized nearly homogeneously with varying mass fraction of alpha-tocopherol. No oxidation of the UHMW-PE could be detected by infrared spectroscopy (FTIR) and HPLC studies showed a very low degradation of the alpha-tocopherol for both processes. PMID:17143764

  10. Orbital Stability of High Mass Planetary Systems

    NASA Astrophysics Data System (ADS)

    Morrison, Sarah J.; Kratter, Kaitlin M.

    2016-05-01

    In light of the observation of systems like HR 8799 that contain several planets with planet-star mass ratios larger than Jupiter's, we explore the relationships between planet separation, mass, and stability timescale for high mass multi-planet systems detectable via direct imaging. We discuss the role of overlap between 1st and sometimes 2nd order mean motion resonances, and show how trends in stability time vary from previous studies of lower mass multi-planet systems. We show that extrapolating empirically derived relationships between planet mass, separation, and stability timescale derived from lower mass planetary systems misestimate the stability timescales for higher mass planetary systems by more than an order of magnitude at separations near the Hill stability limit. We also address what metrics of planet separation are most useful for estimating a system's dynamical stability. We apply these results to young, gapped, debris disk systems of the ScoCen association in order to place limits on the maximum mass and number of planets that could persist for the lifetimes of the disks. These efforts will provide useful constraints for on-going direct imaging surveys. By setting upper limits on the most easily detectable systems, we can better interpret both new discoveries and non-dectections.

  11. Specific outcomes of the research on the radiation stability of the French nuclear glass towards alpha decay accumulation

    NASA Astrophysics Data System (ADS)

    Peuget, S.; Delaye, J.-M.; Jégou, C.

    2014-01-01

    formers and broadening of the ring size distributions, indicating increasing disorder of the glass structure. This structural evolution induced by alpha decays would be driven by the reconstruction of the glass disorganized by displacement cascades of the recoil nuclei, freezing a glass structure with a higher fictive temperature. This “ballistic disordering (BD) fast quenching” event induces a new glassy state characterized by a higher enthalpy state. Accumulation of α decays induce similar phenomena of “BD-fast quenching”, increasing the fraction of the sample volume characterized by a “high enthalpy state”. At dose around 4 × 1018 α g-1 the entire sample volume has been affected by “BD-fast quenching” events at least once, which explain the stabilization of the evolutions of glass structure and properties. Helium behavior was also studied by measuring the helium solubility constants and diffusion coefficients. Helium atoms are incorporated into the glass free volume with a solubility constant that varies less than 10% around a value of about 1011 at cm-3 Pa-1 and a density of solubility sites accessible for helium around 2 × 1021 sites cm-3 which is larger than helium production in a glass package. Helium diffusion experiments performed on infused and Cm doped SON68 glasses indicate that helium migration is controlled by a classical thermally activated diffusion process, whose activation energy (e.g. 0.6 ± 0.03 eV) is not affected by an alpha decay dose of around 1019 α g-1. Helium implantation studies suggest that helium trapping could exist in nanometer size bubbles. SEM and TEM analysis performed on a Cm doped glass damaged by an alpha decay dose of around 1019 α g-1, showed a homogeneous glass without crystallization, phase separation or bubbles with a spatial resolution limit of 10 nm. Bubbles of significant size seem very unlikely to form at room temperatures. But, the ability to form helium bubbles of nanometer size, at temperature below

  12. Lyman-Alpha Observations of High Radial Velocity Stars

    NASA Astrophysics Data System (ADS)

    Bookbinder, Jay

    1990-12-01

    H I LYMAN -ALPHA (LY-A) IS ONE OF THE MOST IMPORTANT LINES EMITTED BY PLASMA IN THE TEMPERATURE RANGE OF 7000 TO 10 TO THE FIFTH POWER K IN LATE-TYPE STARS. IT IS A MAJOR COMPONENT OF THE TOTAL RADIATIVE LOSS RATE, AND IT PLAYS A CRUCIAL ROLE IN DETERMINING THE ATMOSPHERIC STRUCTURE AND IN FLUORESCING OTHER UV LINES. YET IT IS ALSO THE LEAST STUDIED MAJOR LINE IN THE FAR UV, BECAUSE MOST OF THE LINE FLUX IS ABSORBED BY THE ISM ALONG THE LINE OF SIGHT AND BECAUSE IT IS STRONGLY COMTAMINATED BY THE GEOCORONAL BACKGROUND. A KNOWLEDGE OF THE Ly-A PROFILE IS ALSO IMPORTANT FOR STUDIES OF DEUTERIUM IN THE INTERSTELLAR MEDIUM. BY OBSERVING HIGH RADIAL VELOCITY STARS WE WILL OBTAIN FOR THE FIRST TIME HIGH RESOLUTION SPECTRA OF THE CORE OF A STELLAR H I LYMAN-A EMISSION LINE PROFILE.

  13. Cables1 controls p21/Cip1 protein stability by antagonizing proteasome subunit alpha type 3

    PubMed Central

    Shi, Zhi; Li, Zenggang; Li, Zijian; Cheng, Kejun; Du, Yuhong; Fu, Haian; Khuri, Fadlo R.

    2014-01-01

    The cyclin-dependent kinase inhibitor 1A (CDKN1A), p21/Cip1, is a vital cell cycle regulator, dysregulation of which has been associated with a large number of human malignancies. One critical mechanism that controls p21 function is through its degradation, which allows the activation of its associated cell cycle promoting kinases, CDK2 and CDK4. Thus, delineating how p21 is stabilized and degraded will enhance our understanding of cell growth control and offer a basis for potential therapeutic interventions. Here, we report a novel regulatory mechanism that controls the dynamic status of p21 through its interaction with Cdk5 and Abl enzyme substrate 1 (Cables1). Cables1 has a proposed role as a tumor suppressor. We found that upregulation of Cables1 protein was correlated with increased half-life of p21 protein, which was attributed to Cables1/p21 complex formation and supported by their co-localization in the nucleus. Mechanistically, Cables1 interferes with the proteasome (Prosome, Macropain) subunit alpha type 3 (PSMA3) binding to p21 and protects p21 from PSMA3-mediated proteasomal degradation. Moreover, silencing of p21 partially reverses the ability of Cables1 to induce cell death and inhibit cell proliferation. In further support of a potential pathophysiological role of Cables1, the expression level of Cables1 is tightly associated with p21 in both cancer cell lines and human lung cancer patient tumor samples. Together, these results suggest Cables1 as a novel p21 regulator through maintaining p21 stability, and support the model that the tumor suppressive function of Cables1 occurs at least in part through enhancing the tumor suppressive activity of p21. PMID:24975575

  14. Preparation of aqueous alpha-lipoic acid dispersions with octenylsuccinylated high amylose starch.

    PubMed

    Li, Yi-Xuan; Lim, Seung-Taik

    2016-04-20

    Aqueous dispersions prepared with OSA-modified high amylose starch were investigated in comparison with native high amylose starch and beta-cyclodextrin using alpha-lipoic acid as a model substance. Alpha-lipoic acid (ALA), a lipophilic antioxidant essential for energy metabolism in human, was dispersed in gelatinized starch solutions (1.0% w/v) at different temperatures (50-90°C) and times (3-12h). High amylose starch modified with 3% OSA (dry starch base) was most favored in maximizing the dispersibility of ALA (84% recovery) under mild heating (70°C for 3h). The optimally prepared dispersion was milky white and contained particles with a narrow size distribution (200-300nm). The precipitate isolated from the dispersion contained crystalline V-complexes of ALA and amylose while the supernatant contained free ALA accounting for 1/3 of total ALA, indicating OSA-modified high amylose starch stabilized ALA either by complexing with amylose or by retarding aggregation of ALA. PMID:26876852

  15. High-Alpha Handling Qualities Flight Research on the NASA F/A-18 High Alpha Research Vehicle

    NASA Technical Reports Server (NTRS)

    Wichman, Keith D.; Pahle, Joseph W.; Bahm, Catherine; Davidson, John B.; Bacon, Barton J.; Murphy, Patrick C.; Ostroff, Aaron J.; Hoffler, Keith D.

    1996-01-01

    A flight research study of high-angle-of-attack handling qualities has been conducted at the NASA Dryden Flight Research Center using the F/A-18 High Alpha Research Vehicle (HARV). The objectives were to create a high-angle-of-attack handling qualities flight database, develop appropriate research evaluation maneuvers, and evaluate high-angle-of-attack handling qualities guidelines and criteria. Using linear and nonlinear simulations and flight research data, the predictions from each criterion were compared with the pilot ratings and comments. Proposed high-angle-of-attack nonlinear design guidelines and proposed handling qualities criteria and guidelines developed using piloted simulation were considered. Recently formulated time-domain Neal-Smith guidelines were also considered for application to high-angle-of-attack maneuvering. Conventional envelope criteria were evaluated for possible extension to the high-angle-of-attack regime. Additionally, the maneuvers were studied as potential evaluation techniques, including a limited validation of the proposed standard evaluation maneuver set. This paper gives an overview of these research objectives through examples and summarizes result highlights. The maneuver development is described briefly, the criteria evaluation is emphasized with example results given, and a brief discussion of the database form and content is presented.

  16. Hi-alpha forebody design. Part 2: Determination of body shapes for positive directional stability

    NASA Technical Reports Server (NTRS)

    Ravi, R.; Mason, William H.

    1991-01-01

    Computational Fluid Dynamics (CFD) has been used to study aircraft forebody flowfields at low speed high angle-of-attack conditions with sideslip. The purpose is to define forebody geometries which provide good directional stability characteristics under these conditions. The flows of the F-5A forebody and Erickson forebody were recomputed with better and refined grids. The results were obtained using a modified version of cfl3d to solve either the Euler equations or the Reynolds equations employing a form of the Baldwin-Lomax turbulence model. Based on those results, we conclude that current CFD methods can be used to investigate the aerodynamic characteristics of forebodies to achieve desirable high angle-of-attack characteristics. An analytically defined generic forebody model is described, and a systematic study of forebody shapes was then conducted to determine which shapes promote a positive contribution to directional stability at high angle-of-attack. A novel way of presenting the results is used to illustrate how the positive contribution arises. Based on the results of this initial parametric study, some guidelines for aerodynamic design to promote positive directional stability are presented.

  17. Borehole Stability in High-Temperature Formations

    NASA Astrophysics Data System (ADS)

    Yan, Chuanliang; Deng, Jingen; Yu, Baohua; Li, Wenliang; Chen, Zijian; Hu, Lianbo; Li, Yang

    2014-11-01

    In oil and gas drilling or geothermal well drilling, the temperature difference between the drilling fluid and formation will lead to an apparent temperature change around the borehole, which will influence the stress state around the borehole and tend to cause borehole instability in high geothermal gradient formations. The thermal effect is usually not considered as a factor in most of the conventional borehole stability models. In this research, in order to solve the borehole instability in high-temperature formations, a calculation model of the temperature field around the borehole during drilling is established. The effects of drilling fluid circulation, drilling fluid density, and mud displacement on the temperature field are analyzed. Besides these effects, the effect of temperature change on the stress around the borehole is analyzed based on thermoelasticity theory. In addition, the relationships between temperature and strength of four types of rocks are respectively established based on experimental results, and thermal expansion coefficients are also tested. On this basis, a borehole stability model is established considering thermal effects and the effect of temperature change on borehole stability is also analyzed. The results show that the fracture pressure and collapse pressure will both increase as the temperature of borehole rises, and vice versa. The fracture pressure is more sensitive to temperature. Temperature has different effects on collapse pressures due to different lithological characters; however, the variation of fracture pressure is unrelated to lithology. The research results can provide a reference for the design of drilling fluid density in high-temperature wells.

  18. Nuclear alpha spectrin: Critical roles in DNA interstrand cross-link repair and genomic stability.

    PubMed

    Lambert, Muriel W

    2016-09-01

    Non-erythroid alpha spectrin (αIISp) is a structural protein which we have shown is present in the nucleus of human cells. It interacts with a number of nuclear proteins such as actin, lamin, emerin, chromatin remodeling factors, and DNA repair proteins. αIISp's interaction with DNA repair proteins has been extensively studied. We have demonstrated that nuclear αIISp is critical in DNA interstrand cross-link (ICL) repair in S phase, in both genomic (non-telomeric) and telomeric DNA, and in maintenance of genomic stability following ICL damage to DNA. We have proposed that αIISp acts as a scaffold aiding to recruit repair proteins to sites of damage. This involvement of αIISp in ICL repair and telomere maintenance after ICL damage represents new and critical functions for αIISp. These studies have led to development of a model for the role of αIISp in DNA ICL repair. They have been aided by examination of cells from patients with Fanconi anemia (FA), a repair-deficient genetic disorder in which a deficiency in αIISp leads to defective ICL repair in genomic and telomeric DNA, telomere dysfunction, and chromosome instability following DNA ICL damage. We have shown that loss of αIISp in FA cells is due to increased breakdown by the protease, µ-calpain. Importantly, we have demonstrated that this deficiency can be corrected by knockdown of µ-calpain and restoring αIISp levels to normal. This corrects a number of the phenotypic deficiencies in FA after ICL damage. These studies suggest a new and unexplored direction for therapeutically restoring genomic stability in FA cells and for correcting numerous phenotypic deficiencies occurring after ICL damage. Developing a more in-depth understanding of the importance of the interaction of αIISp with other nuclear proteins could significantly enhance our knowledge of the consequences of loss of αIISp on critical nuclear processes. PMID:27480253

  19. Conformational stability of alpha-lactalbumin missing a peptide bond between Asp66 and Pro67.

    PubMed

    Hamada, S; Moriyama, Y; Yamaguchi, K; Takeda, K

    1994-05-01

    The peptide bond between Asp66-Pro67 of alpha-lactalbumin was cleaved with formic acid (cleaved alpha-lactalbumin). Secondary structural changes of the cleaved alpha-lactalbumin, in which the two separated polypeptides were joined by disulfide bridges, were examined in solutions of sodium dodecyl sulfate (SDS), urea, and guanidine hydrochloride. The structural changes of the cleaved alpha-lactalbumin were compared with those of the intact protein. The relative proportions of secondary structures were determined by curve fitting of the circular dichroism. The cleaved alpha-lactalbumin contained 29% alpha-helical structure as against 34% for the intact protein. Some helices of the cleaved alpha-lactalbumin which had been disrupted by the cleavage appeared to be reformed upon the addition of SDS of very low concentration (0.5 mM). In the SDS solution, the helicities of both the intact and cleaved proteins increased, attaining 44% at 4 mM SDS. On the other hand, the helical structures of the cleaved alpha-lactalbumin began to be disrupted at low concentrations of guanidine hydrochloride and urea compared with that of the intact protein. However, no difference was observed in the thermal denaturations of the intact and cleaved proteins, except for the difference in the original helicities. The helicities of both proteins decreased with an increase of temperature up to 65 degrees C and recovered upon cooling. PMID:7986345

  20. High Energy K(alpha) Radiography Using High-intensity, Short-pulse Lasers

    SciTech Connect

    Park, H; Izumi, N; Key, M H; King, J A; Koch, J A; Landen, O L; Patel, P K; Price, D F; Remington, B A; Robey, H F; Snavely, R A; Tabak, M; Town, R J; Wickersham, J E; Stoeckl, C; Storm, M; Theobald, W; Chambers, D M; Eagelton, R; Goldsack, T; Clarke, R J; Heathcote, R; Giraldez, E; Nikroo, A; Steinman, D A; Stephens, R B; Zhang, B B

    2005-11-16

    We have performed experiments using Callisto, the Vulcan 100 TW and the Vulcan Petawatt high intensity lasers to understand the characteristics of high energy, K{alpha} x-ray sources and to implement workable radiography solutions at 20-100 keV. Our measurements show that the K{alpha} size from a simple foil target is larger than 60 {micro}m, far larger than the experiment resolution requirement. The total K{alpha} yield is independent of target thicknesses verifying that refluxing plays a major role in photon generation. Smaller radiating volumes emit brighter K{alpha} radiation. 1-D radiography experiments using small-edge-on foils resolved 10 {micro}m features with high contrast. We tested a variety of small volume 2-D point sources such as cones, wires, and embedded wires, measuring photon yields and comparing our measurements with predictions from hybrid-PIC LSP simulations. In addition to high-energy, high-resolution backlighters, future experiments will also need imaging detectors and diagnostic tools that are workable in the 20-100 keV energy range. An initial look at some of these detector issues is also presented.

  1. Stabilization of high-risk plaques

    PubMed Central

    Takata, Kohei; Zhang, Bo; Miura, Shin-ichiro; Saku, Keijiro

    2016-01-01

    The prevalence of atherosclerotic cardiovascular diseases (ASCVDs) is increasing globally and they have become the leading cause of death in most countries. Numerous experimental and clinical studies have been conducted to identify major risk factors and effective control strategies for ASCVDs. The development of imaging modalities with the ability to determine the plaque composition enables us to further identify high-risk plaque and evaluate the effectiveness of different treatment strategies. While intensive lipid-lowering by statins can stabilize or even regress plaque by various mechanisms, such as the reduction of lipid accumulation in a necrotic lipid core, the reduction of inflammation, and improvement of endothelial function, there are still considerable residual risks that need to be understood. We reviewed important findings regarding plaque vulnerability and some encouraging emerging approaches for plaque stabilization. PMID:27500090

  2. Enriching M. sternomandibularis with alpha-tocopherol by dietary means does not protect against the lipid oxidation caused by high-pressure processing.

    PubMed

    Tume, R K; Sikes, A L; Smith, S B

    2010-01-01

    We hypothesized that elevating the concentration of alpha-tocopherol in beef muscle tissue by dietary means would increase lipid stability following high-pressure processing. Beef M. sternomandibularis was obtained from cattle that had medium (4.92 microg/g) and high (7.30 microg/g) concentrations of alpha-tocopherol. Post-rigor, paired muscles samples were subjected to pressures of 0.1 (atmospheric), 200 or 800 MPa for 20 min at approximately 60 degrees C. Following high-pressure processing, measurements were made immediately (d 0) or on samples stored in the dark for 6 d at 4 degrees C (d 6). Intramuscular lipid was similar for each group (4.02% vs. 4.26%, respectively; P=0.78), but lipid from the medium alpha-tocopherol muscle was more saturated and less monounsaturated than muscle from the high alpha-tocopherol group. High-pressure processing at 800 MPa and 60 degrees C did not reduce the amount of alpha-tocopherol but significantly reduced the concentration of linoleic acid (18:2n-6) in muscle from both production groups of cattle. Thiobarbituric acid reactive substances increased linearly with treatment pressure only in d 6 samples (day x pressure interaction P=0.0001) and were higher overall (P=0.02) in the high alpha-tocopherol muscle than in the medium alpha-tocopherol muscle. At d 6, lipid peroxides were decreased (P=0.007) by high-pressure treatment and were higher (P<0.0001) in the high alpha-tocopherol group than in the medium alpha-tocopherol group. Therefore, muscle from the high alpha-tocopherol cattle in this study had a greater accumulation of lipid peroxides by d 6, making the muscle from those cattle more susceptible to oxidation. PMID:20374755

  3. High sperm chromatin stability in semen with high viscosity.

    PubMed

    Gonzales, G F; Sánchez, A

    1994-01-01

    This study was designed to determine the effects of high semen viscosity on sperm chromatin stability. Semen samples obtained from men with normal and high viscosity were studied. Sperm chromatin stability was tested by exposure to sodium dodecyl sulfate (SDS) only and SDS together with a zinc-chelating agent, disodium ethylene diamine tetraacetate (SDS+EDTA). After SDS incubation, stable sperm was 61.36 +/- 3.0 and 54.71 +/- 3.42% for normal and high semen viscosity, respectively (P:NS), and after SDS+EDTA, it was further reduced to 12.48 +/- 0.99% in semen samples with normal consistency and in a less magnitude in semen samples with high viscosity (25.6 +/- 5.2). Comparing values obtained in SDS+EDTA, a high sperm stability was observed in samples with hyperviscosity (p < .02). In samples with normal viscosity the percentage of grossly swollen sperm increased 5.40 times from the values obtained in sperm incubated with SDS to the values obtained with SDS+EDTA, whereas in samples with high viscosity the percentage increased only 2.2 times. It is concluded that hyperviscosity is associated with a high sperm chromatin stability in situations when a zinc-chelating agent is present. PMID:8122934

  4. High Temperature Stability of Potassium Beta Alumina

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Kisor, A.; Ryan, M. A.

    1996-01-01

    None. From Objectives section: Evaluate the stability of potassium beta alumina under potassium AMTEC operating conditions. Evaluate the stability regime in which potassium beta alumina can be fabricated.

  5. High-Alpha Research Vehicle Lateral-Directional Control Law Description, Analyses, and Simulation Results

    NASA Technical Reports Server (NTRS)

    Davidson, John B.; Murphy, Patrick C.; Lallman, Frederick J.; Hoffler, Keith D.; Bacon, Barton J.

    1998-01-01

    This report contains a description of a lateral-directional control law designed for the NASA High-Alpha Research Vehicle (HARV). The HARV is a F/A-18 aircraft modified to include a research flight computer, spin chute, and thrust-vectoring in the pitch and yaw axes. Two separate design tools, CRAFT and Pseudo Controls, were integrated to synthesize the lateral-directional control law. This report contains a description of the lateral-directional control law, analyses, and nonlinear simulation (batch and piloted) results. Linear analysis results include closed-loop eigenvalues, stability margins, robustness to changes in various plant parameters, and servo-elastic frequency responses. Step time responses from nonlinear batch simulation are presented and compared to design guidelines. Piloted simulation task scenarios, task guidelines, and pilot subjective ratings for the various maneuvers are discussed. Linear analysis shows that the control law meets the stability margin guidelines and is robust to stability and control parameter changes. Nonlinear batch simulation analysis shows the control law exhibits good performance and meets most of the design guidelines over the entire range of angle-of-attack. This control law (designated NASA-1A) was flight tested during the Summer of 1994 at NASA Dryden Flight Research Center.

  6. Neutron-capture element and Sc abundances in low- and high-alpha Galactic halo stars

    NASA Astrophysics Data System (ADS)

    Yong, David; Fishlock, Cherie; Karakas, Amanda

    2015-08-01

    Nissen & Schuster (2010) identified two samples of Galactic halo stars with distinct kinematic and chemical properties. The "high-alpha" population is associated with the dissipative monolithic collapse of a proto-Galactic gas cloud while the "low-alpha" population was likely accreted from dwarf galaxies having experienced slower star formation rates. For a subset of these stars, we measured precise abundances of Sc, Zr, La, Ce, Nd and Eu. We find differences in the abundance ratios of [Sc/Fe], [Zr/Fe], and [La/Zr] between the low- and high-alpha groups. The most intriguing result is that the low-alpha stars appear to have higher [Eu/Fe] ratios than the high-alpha stars, in contrast to the expectation that Eu should follow the alpha elements. These data challenge the hypothesis that the high-alpha stars formed in regions only enriched by massive stars and that the low-alpha received additional enrichment from SNeIa and low-mass AGB stars. This work has three main consequences for galaxy halos: 1. The new Eu data could be explained by different IMFs for the two halo populations; 2. The low [alpha/Fe] ratios in some, and perhaps all, dwarf galaxies may be driven (in part of in whole) by different IMFs rather than SNeIa contributions; 3. These data may provide important new constraints on the origin of Eu.

  7. Determination of alpha-tocopherol and alpha-tocopherylquinone in rat tissues and plasma by high-performance liquid chromatography with electrochemical detection.

    PubMed

    Kanazawa, H; Miyata, C; Nagata, Y; Urano, S; Matsushima, Y

    2000-10-01

    Alpha-tocopherol and alpha-tocopherylquinone in rat tissues and plasma were determined simultaneously by using high-performance liquid chromatography-electrochemical detection (HPLC-ED) with dual electrodes in the series mode. Biological samples were saponified in the presence of a mixture of butylated hydroxytoluene, ascorbic acid, and pyrogallol and then extracted with hexane. The compounds were separated on a C18 column using a mobile phase containing 95% methanol and 0.05 M sodium perchlorate as the supporting electrolyte. After HPLC separation, alpha-tocopherylquinone was first reduced at an upstream electrode at -500 mV Both alpha-tocopherol and the reduction product of alpha-tocopherylquinone were then oxidized downstream at +600 mV. Only the downstream electrode current was monitored for the determination. Linearity of the standard curves was obtained over the range 5-30 pmol for alpha-tocopherol and alpha-tocopherylquinone. Minimum detectable quantities (S/N of 3) were 0.25 pmol for alpha-tocopherol and 0.31 pmol for alpha-tocopherylquinone. The method was applied to analysis of the contents of alpha-tocopherol and alpha-tocopherylquinone in rat tissues and plasma. By hyperoxia, the content of alpha-tocopherol was decreased remarkably in lung, and in contrast, the contents of alpha-tocopherylquinone were increased in all tissues studied with the exception of plasma, though the content of alpha-tocopherylquinone in normal rats is quite small. The technique is particularly useful in the quantitation of the oxidation of alpha-tocopherol in biological samples. PMID:11045451

  8. Chemical stability of high-temperature superconductors

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    1992-01-01

    A review of the available studies on the chemical stability of the high temperature superconductors (HTS) in various environments was made. The La(1.8)Ba(0.2)CuO4 HTS is unstable in the presence of H2O, CO2, and CO. The YBa2Cu3O(7-x) superconductor is highly susceptible to degradation in different environments, especially water. The La(2-x)Ba(x)CuO4 and Bi-Sr-Ca-Cu-O HTS are relatively less reactive than the YBa2Cu3O(7-x). Processing of YBa2Cu3O(7-x) HTS in purified oxygen, rather than in air, using high purity noncarbon containing starting materials is recommended. Exposure of this HTS to the ambient atmosphere should also be avoided at all stages during processing and storage. Devices and components made out of these oxide superconductors would have to be protected with an impermeable coating of a polymer, glass, or metal to avoid deterioration during use.

  9. Membrane-bound states of alpha-lactalbumin: implications for the protein stability and conformation.

    PubMed Central

    Cawthern, K. M.; Permyakov, E.; Berliner, L. J.

    1996-01-01

    alpha-Lactalbumin (alpha-LA) associates with dimyristoylphosphatidylcholine (DMPC) or egg lecithin (EPC) liposomes. Thermal denaturation of isolated DMPC or EPC alpha-LA complexes was dependent on the metal bound state of the protein. The intrinsic fluorescence of thermally denatured DMPC-alpha-LA was sensitive to two thermal transitions: the Tc of the lipid vesicles, and the denaturation of the protein. Quenching experiments suggested that tryptophan accessibility increased upon protein-DMPC association, in contrast with earlier suggestions that the limited emission red shift upon association with the liposome was due to partial insertion of tryptophan into the apolar phase of the bilayer (Hanssens I et al., 1985, Biochim Biophys Acta 817:154-166). On the other hand, above the protein transition (70 degrees C), the spectral blue shifts and reduced accessibility to quencher suggested that tryptophan interacts significantly with the apolar phase of either DMPC and EPC. At pH 2, where the protein inserts into the bilayer rapidly, the isolated DMPC-alpha-LA complex showed a distinct fluorescence thermal transition between 40 and 60 degrees C, consistent with a partially inserted form that possesses some degree of tertiary structure and unfolds cooperatively. This result is significant in light of earlier findings of increased helicity for the acid form, i.e., molten globule state of the protein (Hanssens I et al., 1985, Biochim Biophys Acta 817:154-166). These results suggest a model where a limited expansion of conformation occurs upon association with the membrane at neutral pH and physiological temperatures, with a concomitant increase in the exposure of tryptophan to external quenchers; i.e., the current data do not support a model where an apolar, tryptophan-containing surface is covered by the lipid phase of the bilayer. PMID:8819172

  10. cap alpha. /sup 4/He elastic scattering at high energies

    SciTech Connect

    Usmani, A.A.; Ahmad, I.; Usmani, Q.N.

    1989-03-01

    Differential cross sections for ..cap alpha.. /sup 4/He elastic scattering have been calculated at incident ..cap alpha..-particle momenta of 4.32, 5.07, and 7.0 GeV/c within the framework of Glauber multiple scattering theory. The full Glauber amplitude has been calculated using the Monte Carlo method for evaluating multidimensional integrals. We found that, in general, the more realistic double-Gaussian model for the density brings theory closer to experiment as compared to the generally used single-Gaussian model in some momentum transfer regions. Our results with the double-Gaussian model and an acceptable set of NN parameters are in fairly good agreement with the experimental data at 4.32 and 5.07 GeV/c.

  11. Quench propagation velocity for highly stabilized conductors

    SciTech Connect

    Mints, R.G. |; Ogitsu, T. |; Devred, A.

    1995-05-01

    Quench propagation velocity in conductors having a large amount of stabilizer outside the multifilamentary area is considered. It is shown that the current redistribution process between the multifilamentary area and the stabilizer can strongly effect the quench propagation. A criterion is derived determining the conditions under which the current redistribution process becomes significant, and a model of effective stabilizer area is suggested to describe its influence on the quench propagation velocity. As an illustration, the model is applied to calculate the adiabatic quench propagation velocity for a conductor geometry with a multifilamentary area embedded inside the stabilizer.

  12. Enhancement of lipid stability of broiler breast meat and meat products fed on alpha lipoic acid and alpha tocopherol acetate supplemented feed

    PubMed Central

    2012-01-01

    This study was designed to investigate the effect of alpha lipoic acid (ALA) and alpha tocopherol acetate (ATA) on the antioxidant potential, lipid stability and the quality of the broiler breast meat and meat products. The treatment plan was as (T1 = control feed, T2 = 200 mg ATA + 25 mg ALA/kg feed, T3 = 200 mg ATA + 75 mg ALA/kg feed, T4 = 200 mg ATA + 150 mg ALA/kg feed, T5 = Oxidized oil (4%), T6 = 200 mg ATA + 150 mg ALA + Oxidized oil (4%)/kg feed). After two weeks of acclimatization the birds were fed with ALA and ATA enriched diet. The results revealed that maximum deposition of ALA took place in T4 which contain maximum dose of ALA. The TBARS and DPPH values of the broiler breast meat were in T4 (0.14 ± 0.01 MDA/kg of meat, 76.69 ± 0.14%) and in T5 were (0.24 ± 0.15 MDA/Kg of meat, 44.98 ± 0.04%) accordingly. ATA concentration were also highest in T4 (206.43 ± 0.22 mg/g of meat) and lowest in T5 (79.09 ± 0.06 mg/g of meat). Sensory evaluation results showed that nuggets and patties made of T5 containing oxidized oil were least liked and T4 got highest score. In a nutshell, 150 mg/kg feed dietary supplementation of ALA with constant level of ATA can ameliorate the antioxidant potential, lipid stability and nutritional qualities of broiler breast meat and meat products. PMID:22640892

  13. Stability and control of maneuvering high-performance aircraft

    NASA Technical Reports Server (NTRS)

    Stengel, R. F.; Berry, P. W.

    1977-01-01

    The stability and control of a high-performance aircraft was analyzed, and a design methodology for a departure prevention stability augmentation system (DPSAS) was developed. A general linear aircraft model was derived which includes maneuvering flight effects and trim calculation procedures for investigating highly dynamic trajectories. The stability and control analysis systematically explored the effects of flight condition and angular motion, as well as the stability of typical air combat trajectories. The effects of configuration variation also were examined.

  14. The stability constants of copper(II) complexes with some alpha-amino acids in dioxan-water mixtures.

    PubMed

    Doğan, A; Köseoğlu, F; Kiliç, E

    2001-08-15

    In this study, the overall stability constants of copper(II) complexes with some alpha-amino acids (glycine, dl-alanine, dl-valine, l-leucine, l-asparagine, l-glutamine) were determined by potentiometric titration in water, 25% dioxan-75% water, 35% dioxan-65% water, 50% dioxan-50% water, and 60% dioxan-40% water. The titrations were performed at 25 degrees C, under nitrogen atmosphere, and the ionic strength of the medium was maintained at 0.10 M by using sodium perchlorate. The formation curves of their complexes (n-p[L]) were obtained by means of the titration data. Then the stability constants were determined in relation to these curves. The mol ratio of copper(II) to alpha-amino acid was also determined and it was found that the complexes were CuL(2) type. Another important result obtained was that the tendency of amino acids to form complexes with copper(II) was greater in dioxan-water mixtures compared to water. PMID:11488627

  15. Crystal grain growth during room temperature high pressure Martensitic alpha to omega transformation in zirconium

    SciTech Connect

    Velisavljevic, Nenad; Chesnut, Gary N; Stevens, Lewis L; Dattelbaum, Dana M

    2008-01-01

    Systematic increase in transition pressure with increase in interstitial impurities is observed for the martensitic {alpha} {yields} {omega} structural phase transition in Zr. Significant room temperature crystal grain growth is also observed for the two highest purity samples at this transition, while in the case of the lowest purity sample interstitial impurities obstruct grain growth even as the sample is heated to 1279 K. Our results show the importance of impurities in controlling structural phase stability and other mechanical properties associated with the {alpha} {yields} {omega} structural phase transition.

  16. Alpha-helical stabilization by side chain shielding of backbone hydrogen bonds.

    PubMed

    García, Angel E; Sanbonmatsu, Kevin Y

    2002-03-01

    We study atomic models of the thermodynamics of the structural transition of peptides that form alpha-helices. The effect of sequence variation on alpha-helix formation for alanine-rich peptides, Ac-Ala21-methyl amide (A21) and Ac-A5 (AAARA)3A-methyl amide (Fs peptide), is investigated by atomic simulation studies of the thermodynamics of the helix-coil transition in explicit water. The simulations show that the guanidinium group in the Arg side chains in the Fs peptide interacts with the carbonyl group four amino acids upstream in the chain and desolvates backbone hydrogen bonds. This desolvation can be directly correlated with a higher probability of hydrogen bond formation. We find that Fs has higher helical content than A21 at all temperatures. A small modification in the amber force field reproduces the experimental helical content and helix-coil transition temperatures for the Fs peptide. PMID:11867710

  17. Long-Term Stability of Planets in the Alpha Centauri System

    NASA Astrophysics Data System (ADS)

    Lissauer, Jack; Quarles, Billy

    2015-12-01

    The α Centauri system is billions of years old, so planets are only expected to be found in regions where their orbits are long-lived. We evaluate the extent of the regions within the α Centauri AB star system where small planets are able to orbit for billion-year timescales, and we map the positions in the sky plane where planets on stable orbits about either stellar component may appear. We confirm the qualitative results of Wiegert & Holman (Astron. J. 113, 1445, 1997) regarding the approximate size of the regions of stable orbits of a single planet, which are larger for retrograde orbits relative to the binary than for prograde orbits. Additionally, we find that mean motion resonances with the binary orbit leave an imprint on the limits of orbital stability, and the effects of the Lidov-Kozai mechanism are also readily apparent. Overall, orbits of a single planet in the habitable zones near the plane of the binary are stable, whereas high-inclination orbits are short-lived. However, even well within regions where single planets are stable, multiple planet systems must be significantly more widely-spaced than they need to be around an isolated star in order to be long-lived.

  18. alpha-Amylase production in high cell density submerged cultivation of Aspergillus oryzae and A. nidulans.

    PubMed

    Agger, T; Spohr, A B; Nielsen, J

    2001-01-01

    The effect of biomass concentration on the formation of Aspergillus oryzae alpha-amylase during submerged cultivation with A. oryzae and recombinant A. nidulans strains has been investigated. It was found that the specific rate of alpha-amylase formation in chemostats decreased significantly with increasing biomass concentration in the range of approx. 2-12 g dry weight kg(-1). When using a recombinant A. nidulans strain in which the gene responsible for carbon catabolite repression of the A. oryzae alpha-amylase gene (creA) was deleted, no significant decrease in the specific rate of alpha-amylase formation was observed. On the basis of the experimental results, it is suggested that the low value of the specific alpha-amylase productivity observed at high biomass concentration is caused by slow mixing of the concentrated feed solution in the viscous fermentation medium. PMID:11234963

  19. High glucose concentrations attenuate hypoxia-inducible factor-1{alpha} expression and signaling in non-tumor cells

    SciTech Connect

    Dehne, Nathalie; Bruene, Bernhard

    2010-04-15

    Hypoxia-inducible factor (HIF) is the major transcription factor mediating adaption to hypoxia e.g. by enhancing glycolysis. In tumor cells, high glucose concentrations are known to increase HIF-1{alpha} expression even under normoxia, presumably by enhancing the concentration of tricarboxylic acid cycle intermediates, while reactions of non-tumor cells are not well defined. Therefore, we analyzed cellular responses to different glucose concentrations in respect to HIF activation comparing tumor to non-tumor cells. Using cells derived from non-tumor origin, we show that HIF-1{alpha} accumulation was higher under low compared to high glucose concentrations. Low glucose allowed mRNA expression of HIF-1 target genes like adrenomedullin. Transfection of C{sub 2}C{sub 12} cells with a HIF-1{alpha} oxygen-dependent degradation domaine-GFP fusion protein revealed that prolyl hydroxylase (PHD) activity is impaired at low glucose concentrations, thus stabilizing the fusion protein. Mechanistic considerations suggested that neither O{sub 2} redistribution nor an altered redox state explains impaired PHD activity in the absence of glucose. In order to affect PHD activity, glucose needs to be metabolized. Amino acids present in the medium also diminished HIF-1{alpha} expression, while the addition of fatty acids did not. This suggests that glucose or amino acid metabolism increases oxoglutarate concentrations, which enhances PHD activity in non-tumor cells. Tumor cells deprived of glutamine showed HIF-1{alpha} accumulation in the absence of glucose, proposing that enhanced glutaminolysis observed in many tumors enables these cells to compensate reduced oxoglutarate production in the absence of glucose.

  20. Localization of a highly divergent mammalian testicular alpha tubulin that is not detectable in brain.

    PubMed Central

    Hecht, N B; Distel, R J; Yelick, P C; Tanhauser, S M; Driscoll, C E; Goldberg, E; Tung, K S

    1988-01-01

    Sequence analysis of a mouse testicular alpha-tubulin partial cDNA, pRD alpha TT1, reveals an isotype that differs from both the somatic and the predominant testicular alpha tubulins at approximately 30% of the 212 amino acid residues determined. Although this mouse testicular cDNA retains the highly conserved sequence, Glu-Gly-Glu-Glu, found in the carboxyl termini of many alpha tubulins, the protein extends substantially beyond this sequence and does not terminate with a C-terminal tyrosine. Using rabbit antiserum prepared to a novel synthetic peptide predicted from this mouse testis alpha-tubulin cDNA, we have have detected by immunoblot and indirect immunofluorescence an antigenic epitope present in testicular alpha tubulin that is not detectable in brain alpha tubulins. We find that the antiserum specifically binds to the manchettes and meiotic spindles of the mouse testis but not with neural fibers or tubulin extracts of the adult mouse brain. These results demonstrate that at least one of the multiple alpha-tubulin isotypes of the mammalian testis is expressed and used in male germ cells but not in the brain. Images PMID:3352610

  1. Rotordynamic stability problems and solutions in high pressure turbocompressors

    NASA Technical Reports Server (NTRS)

    Schmied, J.

    1989-01-01

    The stability of a high pressure compressor is investigated with special regard to the self-exciting effects in oil seals and labyrinths. It is shown how to stabilize a rotor in spite of these effects and even increase its stability with increasing pressure.

  2. High-stability detectors for radioastronomical receivers

    NASA Astrophysics Data System (ADS)

    Teuber, Ute; Schmidt, Axel

    The increased bandwidths of radioastronomical receivers has increased the detector stability requirements. A detector with a short-term stability of 0.01 percent, required in a receiver with a 9 mm wavelength receiver, could not be achieved using previously available detectors and dc amplifiers. This paper describes a switched detector which meets these requirements, and presents resulting rms values as a function of integration time.

  3. Effect of neohesperidin dihydrochalcone on the activity and stability of alpha-amylase: a comparative study on bacterial, fungal, and mammalian enzymes.

    PubMed

    Kashani-Amin, Elaheh; Ebrahim-Habibi, Azadeh; Larijani, Bagher; Moosavi-Movahedi, Ali Akbar

    2015-10-01

    Neohesperidin dihydrochalcone (NHDC) was recently introduced as an activator of mammalian alpha-amylase. In the current study, the effect of NHDC has been investigated on bacterial and fungal alpha-amylases. Enzyme assays and kinetic analysis demonstrated the capability of NHDC to significantly activate both tested alpha-amylases. The ligand activation pattern was found to be more similar between the fungal and mammalian enzyme in comparison with the bacterial one. Further, thermostability experiments indicated a stability increase in the presence of NHDC for the bacterial enzyme. In silico (docking) test locates a putative binding site for NHDC on alpha-amylase surface in domain B. This domain shows differences in various alpha-amylase types, and the different behavior of the ligand toward the studied enzymes may be attributed to this fact. PMID:25808616

  4. Measurement and analysis of quadruple ({alpha}{gamma}{gamma}) angular correlations for high spin states of {sup 24}Mg.

    SciTech Connect

    Wiedenhover, I.; Wuosmaa, A. H.; Lister, C. J.; Carpenter, M. P.; Janssens, R. V. F.; Amro, H.; Caggiano, J.; Heinz, A.; Kondev, F. G.; Lauritsen, T.; Siem, S.; Sonzogni, A.; Bhattacharyya, P.; Devlin, M.; Sarantites, D. G.; Sobotka, L. G.

    2000-10-30

    The high-lying, {alpha}-decaying states in {sup 24}Mg have been studied by measuring the complete decay path of {alpha} and {gamma} emissions using five segmented Silicon detectors in conjunction with GAMMASPHERE. The authors analyzed the ({alpha}{gamma}) triple angular correlations and, for the first time, ({alpha}{gamma}{gamma}) quadruple correlations. The data analysis is based on a new Fourier transformation technique. The power of the technique is demonstrated.

  5. Fumarate hydratase deficiency in renal cancer induces glycolytic addiction and hypoxia-inducible transcription factor 1alpha stabilization by glucose-dependent generation of reactive oxygen species.

    PubMed

    Sudarshan, Sunil; Sourbier, Carole; Kong, Hye-Sik; Block, Karen; Valera Romero, Vladimir A; Yang, Youfeng; Galindo, Cynthia; Mollapour, Mehdi; Scroggins, Bradley; Goode, Norman; Lee, Min-Jung; Gourlay, Campbell W; Trepel, Jane; Linehan, W Marston; Neckers, Len

    2009-08-01

    Hereditary leiomyomatosis and renal cell cancer (HLRCC) is an inherited cancer syndrome linked to biallelic inactivation of the gene encoding the tricarboxylic acid cycle enzyme fumarate hydratase (FH). Individuals with HLRCC are at risk to develop cutaneous and uterine leiomyomas and an aggressive form of kidney cancer. Pseudohypoxic drive-the aberrant activation of cellular hypoxia response pathways despite normal oxygen tension-is considered to be a likely mechanism underlying the etiology of this tumor. Pseudohypoxia requires the oxygen-independent stabilization of the alpha subunit of the hypoxia-inducible transcription factor (HIF-1alpha). Under normoxic conditions, proline hydroxylation of HIF-1alpha permits VHL recognition and subsequent targeting for proteasomal degradation. Here, we demonstrate that inactivating mutations of FH in an HLRCC-derived cell line result in glucose-mediated generation of cellular reactive oxygen species (ROS) and ROS-dependent HIF-1alpha stabilization. Additionally, we demonstrate that stable knockdown of FH in immortalized renal epithelial cells results in ROS-dependent HIF-1alpha stabilization. These data reveal that the obligate glycolytic switch present in HLRCC is critical to HIF stabilization via ROS generation. PMID:19470762

  6. Elongation factor 1 alpha concentration is highly correlated with the lysine content of maize endosperm.

    PubMed Central

    Habben, J E; Moro, G L; Hunter, B G; Hamaker, B R; Larkins, B A

    1995-01-01

    Lysine is the most limiting essential amino acid in cereals, and for many years plant breeders have attempted to increase its concentration to improve the nutritional quality of these grains. The opaque2 mutation in maize doubles the lysine content in the endosperm, but the mechanism by which this occurs is unknown. We show that elongation factor 1 alpha (EF-1 alpha) is overexpressed in opaque2 endosperm compared with its normal counterpart and that there is a highly significant correlation between EF-1 alpha concentration and the total lysine content of the endosperm. This relationship is also true for two other cereals, sorghum and barley. It appears that genetic selection for genotypes with a high concentration of EF-1 alpha can significantly improve the nutritional quality of maize and other cereals. Images Fig. 1 Fig. 2 PMID:7567989

  7. Ly alpha and IR galaxy companions of high redshift damped Ly alpha QSO absorbers

    NASA Technical Reports Server (NTRS)

    Caulet, Adeline; Mccaughrean, Mark

    1993-01-01

    We have used a Near-Infrared Camera and Multi-Object Spectrometer (NICMOS3) HgCdTe 256x256 array detector with the Infrared (IR) camera on the 2.3m telescope at Steward Observatory to image several Quasi-Stellar Object (QSO) fields. The limiting magnitude is K'(2.1 microns) = 21.0 - 21.5 mag per square arcsec for a 3 sigma detection in 3 hours of in-field chopping observations. Each QSO line-of-sight samples several known absorbers with Mg2(lambda)2796-2803 A and/or C4(lambda)1548-1551 A absorption doublets. The equivalent width distributions of the low and high ionization absorption lines of the absorber sample are identical to those of the parent population of all absorbers. This selection process, used already for a spectroscopic survey of Mg2 absorption lines in C4-selected absorption systems at high z, gives a methodical approach to observing, reduces the observer biases, and makes a more efficient use of telescope time. This selection guarantees that imaging of the sample of QSO fields will provide complete sampling of the whole population of high z QSO absorbers. Follow-up optical and IR spectroscopy of these objects is scheduled for redshift measurement and confirmation of the absorbing galaxies and the cluster members.

  8. Solution Processible alpha,omega-Distyryl Oligothiophene Semiconductors with Enhanced Environmental Stability

    SciTech Connect

    Mauldin, C.; Murphy, A; Liao, F; Frechet, J; Subramanian, V; DeLongchamp, D; Fischer, D; Toney, M

    2009-01-01

    We describe the rational design of oligothiophene semiconductors to facilitate solution-based fabrication of environmentally stable organic field-effect transistors (OFETs). Ultrathin films of ?,?-distyryl quaterthiophene (DS4T), pentathiophene (DS5T), and sexithiophene (DS6T) were prepared via solution processing to probe the effect of styryl end groups, oligomer length, and thin film structure on air stability. These films were prepared via solution deposition and thermal annealing of precursors featuring thermally labile ester solubilizing groups. A detailed study of the thin film structure was performed using atomic force microscopy (AFM), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and grazing incidence X-ray diffraction (GIXD). Functional OFETs were obtained for DS5T and DS6T and have, respectively, hole mobilities of 0.051 and 0.043 cm2/(V s) and on/off ratios of 1 x 105 to 1 x 106, whereas DS4T OFETs failed to function because of poor film continuity. The effect of both short-term and long-term exposure to air is tracked in OFETs revealing remarkable stability for both DS5T and DS6T. This stability is attributed to the elimination of reactive sites in ?,?-distyryl oligothiophenes and suggests that careful choice of end-group structure can stabilize these molecules against oxidative degradation.

  9. ON THE ORIGINS OF THE HIGH-LATITUDE H{alpha} BACKGROUND

    SciTech Connect

    Witt, Adolf N.; Vijh, Uma P.; Gold, Benjamin; Barnes, Frank S.; DeRoo, Casey T.; Madsen, Gregory J.

    2010-12-01

    The diffuse high-latitude H{alpha} background is widely believed to be predominantly the result of in situ recombination of ionized hydrogen in the warm interstellar medium of the Galaxy. Instead, we show that both a substantial fraction of the diffuse high-latitude H{alpha} intensity in regions dominated by Galactic cirrus dust and much of the variance in the high-latitude H{alpha} background are the result of scattering by interstellar dust of H{alpha} photons originating elsewhere in the Galaxy. We provide an empirical relation, which relates the expected scattered H{alpha} intensity to the IRAS 100 {mu}m diffuse background intensity, applicable to about 81% of the entire sky. The assumption commonly made in reductions of cosmic microwave background observations, namely that the observed all-sky map of diffuse H{alpha} light is a suitable template for Galactic free-free foreground emission, is found to be in need of reexamination.

  10. WERE PROGENITORS OF LOCAL L* GALAXIES Ly{alpha} EMITTERS AT HIGH REDSHIFT?

    SciTech Connect

    Yajima, Hidenobu; Li Yuexing; Zhu Qirong; Gronwall, Caryl; Ciardullo, Robin; Abel, Tom

    2012-08-01

    The Ly{alpha} emission has been observed from galaxies over a redshift span z {approx} 0-8.6. However, the evolution of high-redshift Ly{alpha} emitters (LAEs), and the link between these populations and local galaxies, remains poorly understood. Here, we investigate the Ly{alpha} properties of progenitors of a local L* galaxy by combining cosmological hydrodynamic simulations with three-dimensional radiative transfer calculations using the new ART{sup 2} code. We find that the main progenitor (the most massive one) of a Milky-Way-like galaxy has a number of Ly{alpha} properties close to those of observed LAEs at z {approx} 2-6, but most of the fainter ones appear to fall below the detection limits of current surveys. The Ly{alpha} photon escape fraction depends sensitively on a number of physical properties of the galaxy, such as mass, star formation rate, and metallicity, as well as galaxy morphology and orientation. Moreover, we find that high-redshift LAEs show blueshifted Ly{alpha} line profiles characteristic of gas inflow, and that the Ly{alpha} emission by excitation cooling increases with redshift, and becomes dominant at z {approx}> 6. Our results suggest that some observed LAEs at z {approx} 2-6 with luminosity of L{sub Ly{alpha}} {approx} 10{sup 42}-10{sup 43} erg s{sup -1} may be similar to the main progenitor of the Milky Way at high redshift, and that they may evolve into present-day L* galaxies.

  11. Synthesis and characterization of a high affinity radioiodinated probe for the alpha 2-adrenergic receptor

    SciTech Connect

    Lanier, S.M.; Hess, H.J.; Grodski, A.; Graham, R.M.; Homcy, C.J.

    1986-03-01

    The availability of radioiodinated probes has facilitated the localization and molecular characterization of cell membrane receptors for hormones and neurotransmitters. However, such probes are not available for the study of the alpha 2-adrenergic receptor. This report describes the synthesis and characterization of functionalized derivatives of the selective alpha 2-adrenergic antagonists, rauwolscine and yohimbine, which can be radiolabeled to high specific activity with 125I. Following demethylation of rauwolscine or yohimbine, the resultant carboxylic acid derivatives were reacted with 4-aminophenethylamine to yield the respective 4-aminophenethyl carboxamides, 17 alpha-hydroxy-20 alpha-yohimban-16 beta-(N-4-amino-phenethyl)carboxamide (rau-pAPC) and 17 alpha-hydroxy-20 beta-yohimban-16 alpha-(N-4-aminophenethyl)carboxamide. In competitive inhibition studies using rat renal membranes and the radioligand (3H)rauwolscine, rau-pAPC (Ki = 11 +/- 1 nM) exhibited a 14-fold greater affinity than the corresponding yohimbine derivative (Ki = 136 +/- 45 nM). The higher affinity compound, rau-pAPC, was radioiodinated by the chloramine T method, and the product, 125I-rau-pAPC (17 alpha-hydroxy-20 alpha-yohimban-16 beta-(N-4-amino-3 -(125I)iodophenethyl)carboxamide), was purified by reverse phase HPLC to high specific activity (2175 Ci/mmol) and its binding characteristics were investigated in rat kidney membranes. Specific binding of 125I-rau-pAPC was saturable and of high affinity as determined by Scatchard analysis (KD = 1.8 +/- 0.3 nM) or from kinetic studies (KD = k2/k1 = 0.056 +/- 0.013 min-1)/4.3 +/- 0.2 X 10(7) M-1 min-1 = 1.3 +/- 0.3 nM).

  12. The use of poly(ethylene oxide) for the efficient stabilization of entrapped alpha-chymotrypsin in silicone elastomers: a chemometric study.

    PubMed

    Ragheb, Amro M; Hileman, Oliver E; Brook, Michael

    2005-12-01

    The enzyme alpha-chymotrypsin, a model for catalytic proteins, was entrapped in different silicone elastomers that were formed via the condensation-cure room temperature vulcanization (CC-RTV) of silanol terminated poly(dimethylsiloxane) with tetraethyl orthosilicate as a crosslinker, in the presence of different poly(ethylene oxide) oligomers that were functionalized with triethoxysilyl groups. The effects of various chemical factors on both the activity and entrapping efficiency of proteins (leaching) were studied using a 2-level fractional factorial design--a chemometrics approach. The factors studied include the concentration and chain length of poly(ethylene oxide), enzyme content, and crosslinker (TEOS) concentration. The study indicated that poly(ethylene oxide) can stabilize the entrapped alpha-chymotrypsin in silicone rubber: the specific activity can be maximized by incorporating a relatively high content of short chain, functional PEO. Increased enzyme concentration was found to adversely affect the specific activity. The effect of TEOS was found to be insignificant when PEO was present in the elastomer, however, it does affect the activity positively in the case of simple elastomers. PMID:15992922

  13. Polymer stabilization of the smectic C-alpha* liquid crystal phase—Over tenfold thermal stabilization by confining networks of photo-polymerized reactive mesogens

    SciTech Connect

    Labeeb, A.; Gleeson, H. F.; Hegmann, T.

    2015-12-07

    The smectic C*-alpha (SmC{sub α}*) phase is one of the sub-phases of ferroelectric liquid crystals that has drawn much interest due to its electro-optical properties and ultrafast switching. Generally observed above the ferroelectric SmC* phase in temperature, the SmC{sub α}* commonly shows only very narrow phase temperature range of a few degree Celsius. To broaden the SmC{sub α}* phase, polymer stabilization was investigated for thermal phase stabilization. Two different reactive monomers were tested in three mixtures, and all three broadened the temperature range of the SmC{sub α}* phase from 3 °C to 39 °C. The current reversal method was used to determine the phase existence versus temperature. Moreover, the texture and network structure was studied by polarized optical microscopy and scanning electron microscopy, with the latter revealing the confinement of the smectic layer structure within the porous polymer network.

  14. Connecting two proteins using a fusion alpha helix stabilized by a chemical cross linker

    PubMed Central

    Jeong, Woo Hyeon; Lee, Haerim; Song, Dong Hyun; Eom, Jae-Hoon; Kim, Sun Chang; Lee, Hee-Seung; Lee, Hayyoung; Lee, Jie-Oh

    2016-01-01

    Building a sophisticated protein nano-assembly requires a method for linking protein components in a predictable and stable structure. Most of the cross linkers available have flexible spacers. Because of this, the linked hybrids have significant structural flexibility and the relative structure between their two components is largely unpredictable. Here we describe a method of connecting two proteins via a ‘fusion α helix' formed by joining two pre-existing helices into a single extended helix. Because simple ligation of two helices does not guarantee the formation of a continuous helix, we used EY-CBS, a synthetic cross linker that has been shown to react selectively with cysteines in α-helices, to stabilize the connecting helix. Formation and stabilization of the fusion helix was confirmed by determining the crystal structures of the fusion proteins with and without bound EY-CBS. Our method should be widely applicable for linking protein building blocks to generate predictable structures. PMID:26980593

  15. Connecting two proteins using a fusion alpha helix stabilized by a chemical cross linker

    NASA Astrophysics Data System (ADS)

    Jeong, Woo Hyeon; Lee, Haerim; Song, Dong Hyun; Eom, Jae-Hoon; Kim, Sun Chang; Lee, Hee-Seung; Lee, Hayyoung; Lee, Jie-Oh

    2016-03-01

    Building a sophisticated protein nano-assembly requires a method for linking protein components in a predictable and stable structure. Most of the cross linkers available have flexible spacers. Because of this, the linked hybrids have significant structural flexibility and the relative structure between their two components is largely unpredictable. Here we describe a method of connecting two proteins via a `fusion α helix' formed by joining two pre-existing helices into a single extended helix. Because simple ligation of two helices does not guarantee the formation of a continuous helix, we used EY-CBS, a synthetic cross linker that has been shown to react selectively with cysteines in α-helices, to stabilize the connecting helix. Formation and stabilization of the fusion helix was confirmed by determining the crystal structures of the fusion proteins with and without bound EY-CBS. Our method should be widely applicable for linking protein building blocks to generate predictable structures.

  16. High-Alpha Research Vehicle (HARV) longitudinal controller: Design, analyses, and simulation resultss

    NASA Technical Reports Server (NTRS)

    Ostroff, Aaron J.; Hoffler, Keith D.; Proffitt, Melissa S.; Brown, Philip W.; Phillips, Michael R.; Rivers, Robert A.; Messina, Michael D.; Carzoo, Susan W.; Bacon, Barton J.; Foster, John F.

    1994-01-01

    This paper describes the design, analysis, and nonlinear simulation results (batch and piloted) for a longitudinal controller which is scheduled to be flight-tested on the High-Alpha Research Vehicle (HARV). The HARV is an F-18 airplane modified for and equipped with multi-axis thrust vectoring. The paper includes a description of the facilities, a detailed review of the feedback controller design, linear analysis results of the feedback controller, a description of the feed-forward controller design, nonlinear batch simulation results, and piloted simulation results. Batch simulation results include maximum pitch stick agility responses, angle of attack alpha captures, and alpha regulation for full lateral stick rolls at several alpha's. Piloted simulation results include task descriptions for several types of maneuvers, task guidelines, the corresponding Cooper-Harper ratings from three test pilots, and some pilot comments. The ratings show that desirable criteria are achieved for almost all of the piloted simulation tasks.

  17. High tumor necrosis factor alpha (TNF-alpha) production in Trypanosoma cruzi-infected pregnant mice and increased TNF-alpha gene transcription in their offspring.

    PubMed Central

    Rivera, M T; Marques de Araujo, S; Lucas, R; Deman, J; Truyens, C; Defresne, M P; de Baetselier, P; Carlier, Y

    1995-01-01

    Since tumor necrosis factor alpha (TNF-alpha) is known to be involved in the feto-maternal relationship, this cytokine was studied in Trypanosoma cruzi-infected pregnant BALB/c mice and their fetuses and offspring. Pregnant chronically infected mice displayed significantly higher levels of circulating TNF-alpha than animals either only infected or only pregnant. TNF-alpha was undetectable in sera of uninfected and nonpregnant mice as well as in breast milk obtained from infected and uninfected animals. Fetuses from infected mice exhibited significantly more cells containing TNF-alpha mRNA in their thymus than fetuses from uninfected mothers. When infected 2 months after birth, offspring born to infected and uninfected mothers displayed similar amounts of circulating TNF-alpha during chronic infection, whereas this cytokine was only weakly detectable during the acute phase of the disease. An intravenous injection of lipopolysaccharide during acute infection strongly increased the production of TNF-alpha in offspring born to infected mothers to levels higher than those in progeny from uninfected mice. These results suggest that TNF-alpha is an important cytokine in the feto-maternal relationship during T. cruzi infection and that fetuses and offspring of infected mothers are primed to produce elevated levels of TNF-alpha. PMID:7822027

  18. F-18 HARV in high-alpha flight with smoke generator

    NASA Technical Reports Server (NTRS)

    1989-01-01

    The NASA Dryden Flight Research Center, Edwards, California, used an F-18 Hornet fighter aircraft as its High Angle-of-Attack (alpha) Research Vehicle (HARV) in a three-phased flight research program lasting from April 1987 until September 1996. The aircraft completed 385 research flights and demonstrated stabilized flight at angles of attack between 65 and 70 degrees using thrust vectoring vanes, a research flight control system, and (eventually) forebody strakes (hinged structures on the forward side of the fuselage to provide control by interacting with vortices that are generated at high angles of attack, and thus create side forces). This combination of technologies provided carefree handling of a fighter aircraft in a part of the flight regime that was otherwise very dangerous. Flight research with the HARV increased our understanding of flight at high angles of attack, enabling designers of U.S. fighter aircraft to design airplanes that will fly safely in portions of the flight envelope that pilots previously had to avoid. Angle of attack (alpha) is an aeronautical term that describes the angle of an aircraft body and wings relative to its actual flightpath. During maneuvers, pilots often fly at extreme angles of attack -- with the nose pitched up while the aircraft continues in its original direction. This can lead to conditions in which the airflow becomes separated over large regions of the lifting surfaces (airfoils). These conditions can result in insufficient lift to maintain altitude or control of the aircraft and a corresponding increase in drag -- a condition known as stall. (In an ideal situation, the airflow would remain attached to the airfoil surface from leading to trailing edge; this would reduce the drag that impedes the movement of the airfoil through the atmosphere. When the airflow separates from the surface, this increases the drag and can lead to a stall.) The HARV was developed from a pre-production model of the F-18, a single

  19. Stabilizers: indispensable substances in dairy products of high rheology.

    PubMed

    Tasneem, Madiha; Siddique, Farzana; Ahmad, Asif; Farooq, Umar

    2014-01-01

    The functionality of stabilizers is apparent in many food applications including dairy products. The role of stabilizers like gelatin, pectins, alginates, carboxymethylcellulose, gums, ispghol, sago starch, and chitosan in the development of dairy products of high rheology, like yoghurt, ice cream, and flavored milk, is discussed in this review. Attention is also paid to comprehend on interactions among milk proteins, minerals, and other milk constituents with the reactive sites of stabilizers to get the desirable properties such as appearance, body and texture, mouthfeel, consistency. The role played by stabilizers in the control of syneresis and overrun problems in the high-rheology dairy products is also the topic of discussion. PMID:24499066

  20. Radiation promotes malignant progression of glioma cells through HIF-1alpha stabilization.

    PubMed

    Kim, Young-Heon; Yoo, Ki-Chun; Cui, Yan-Hong; Uddin, Nizam; Lim, Eun-Jung; Kim, Min-Jung; Nam, Seon-Young; Kim, In-Gyu; Suh, Yongjoon; Lee, Su-Jae

    2014-11-01

    Given its contribution to malignant phenotypes of cancer, tumor hypoxia has been considered as a potential therapeutic problem. In the stressful microenvironment condition, hypoxia inducible factor 1 (HIF1) is well known to mediate the transcriptional adaptation of cells to hypoxia and acts as a central player for the process of hypoxia-driven malignant cancer progression. Here, we found that irradiation causes the HIF1α protein to stabilize, even in normoxia condition through activation of p38 MAPK, thereby promoting angiogenesis in tumor microenvironment and infiltrative property of glioma cells. Notably, irradiation reduced hydroxylation of HIF1α through destabilization of prolyl hydroxylases (PHD)-2. Moreover, radiation also decreased the half-life of protein von Hippel-Lindau (pVHL), which is a specific E3 ligase for HIF1α. Of note, inhibition of p38 MAPK attenuated radiation-induced stabilization of HIF1α through destabilization of PHD-2 and pVHL. In agreement with these results, targeting of either p38 MAPK, HIF1α, pVHL or PHD-2 effectively mitigated the radiation-induced tube formation of human brain-derived micro-vessel endothelial cells (HB-MEC) and infiltration of glioma cells. Taken together, our findings suggest that targeting HIF1α in combination with ionizing radiation might increase the efficacy of radiotherapy for glioma treatment. PMID:25109450

  1. Nuclear reactions induced by high-energy alpha particles

    NASA Technical Reports Server (NTRS)

    Shen, B. S. P.

    1974-01-01

    Experimental and theoretical studies of nuclear reactions induced by high energy protons and heavier ions are included. Fundamental data needed in the shielding, dosimetry, and radiobiology of high energy particles produced by accelerators were generated, along with data on cosmic ray interaction with matter. The mechanism of high energy nucleon-nucleus reactions is also examined, especially for light target nuclei of mass number comparable to that of biological tissue.

  2. Naftopidil, a novel alpha1-adrenoceptor antagonist, displays selective inhibition of canine prostatic pressure and high affinity binding to cloned human alpha1-adrenoceptors.

    PubMed

    Takei, R; Ikegaki, I; Shibata, K; Tsujimoto, G; Asano, T

    1999-04-01

    The pharmacological profiles of the alpha1-adrenoceptor antagonists naftopidil, tamsulosin and prazosin were studied in an anesthetized dog model that allowed the simultaneous assessment of their antagonist potency against phenylephrine-mediated increases in prostatic pressure and mean blood pressure. The intravenous administration of each of these compounds dose-dependently inhibited phenylephrine-induced increases in prostatic pressure and mean blood pressure. To further assess the ability of the three compounds to inhibit phenylephrine-induced responses, the doses required to produce a 50% inhibition of the phenylephrine-induced increases in prostatic and mean blood pressure and the selectivity index obtained from the ratio of those two doses were determined for each test compound. Forty minutes after the intravenous administration of naftopidil, the selectivity index was 3.76, and those of tamsulosin and prazosin were 1.23 and 0.61, respectively. These findings demonstrated that naftopidil selectively inhibited the phenylephrine-induced increase in prostatic pressure compared with mean blood pressure in the anesthetized dog model. The selectivity of naftopidil for prostatic pressure was the most potent among the test compounds. In addition, using cloned human alpha1-adrenoceptor subtypes, naftopidil was selective for the alpha1d-adrenoceptor with approximately 3- and 17-fold higher affinity than for the alpha1a- and alpha1b-adrenoceptor subtypes, respectively. The selectivity of naftopidil for prostatic pressure may be attributable to its high binding affinity for alpha1a- and alpha1d-adrenoceptor subtypes. PMID:10361884

  3. Stark broadening of high-principal-quantum-number n-alpha lines of hydrogen.

    NASA Technical Reports Server (NTRS)

    Lasalle, T. R.; Nee, T.-J.; Griem, H. R.

    1973-01-01

    High n-alpha lines (transitions n + 1 to n) with quantum numbers n between 50 and 250 have been observed emanating from galactic H II regions where the electron density and temperature are about 1000/cu cm and 1 eV, respectively. High n-alpha lines have not previously been seen in the laboratory where fairly homogeneous plasmas may be produced and relatively precise measurements of electron densities and temperatures can be made. The present work describes experiments where the first members of the hydrogen line series with lower states n = 10, 11, 12, and 13 have been detected in a laboratory plasma. The width of the 12-alpha line at 88.7 microns could be measured and was consistent with calculated broadening from elastic electron collisions and quasi-static ion effects.

  4. Selective and controlled synthesis of alpha- and beta-cobalt hydroxides in highly developed hexagonal platelets.

    PubMed

    Liu, Zhaoping; Ma, Renzhi; Osada, Minoru; Takada, Kazunori; Sasaki, Takayoshi

    2005-10-12

    We report on the controlled synthesis of single-crystal platelets of alpha- and beta-Co(OH)2 via homogeneous precipitation using hexamethylenetetramine as a hydrolysis agent. The alpha- and beta-Co(OH)2 hexagonal platelets of several micrometers in width and about 15 nm in thickness were reproducibly yielded in rather dilute CoCl2 solutions in the presence and absence of NaCl at 90 degrees C, respectively. The phase and size control of the products were achieved by varying both CoCl2 and NaCl concentrations. Polarized optical microscope observations revealed clear liquid crystallinity of colloidal suspensions of these high aspect-ratio platelets. The as-prepared alpha-Co(OH)2 containing interlayer chloride ions was intercalated with various inorganic or organic anions, keeping its high crystallinity and hexagonal platelike morphology. PMID:16201808

  5. Phase stabilization of VO2 thin films in high vacuum

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Tian; Eaton, Craig; Ye, Hansheng; Engel-Herbert, Roman

    2015-11-01

    A new growth approach to stabilize VO2 on Al2O3 in high vacuum is reported by reducing vanadium oxytriisopropoxide (VTIP) with vanadium metal. Phase stabilization and surface wetting behavior were studied as a function of growth parameters. The flux balance of VTIP to V in combination with growth temperature was identified to be critical for the growth of high quality VO2 thin films. High V fluxes were required to suppress the island formation and to ensure a coalesced film, while too high V fluxes ultimately favored the formation of the undesired, epitaxially stabilized V2O3 phase. Careful optimization of growth temperature, VTIP to V ratio, and growth rate led to high quality single phase VO2 thin films with >3.5 orders of magnitude change in resistivity across the metal-to-insulator transition. This approach opens up another synthesis avenue to stabilize oxide thin films into desired phases.

  6. A Dual-Purpose Linker for Alpha Helix Stabilization and Imaging Agent Conjugation to Glucagon-Like Peptide-1 Receptor Ligands

    PubMed Central

    Zhang, Liang; Navaratna, Tejas; Liao, Jianshan; Thurber, Greg M.

    2016-01-01

    Peptides display many characteristics of efficient imaging agents such as rapid targeting, fast background clearance, and low non-specific cellular uptake. However, poor stability, low affinity, and loss of binding after labeling often preclude their use in vivo. Using the glucagon-like peptide-1 receptor (GLP-1R) ligands exendin and GLP-1 as a model system, we designed a novel alpha helix stabilizing linker to simultaneously address these limitations. The stabilized and labeled peptides showed an increase in helicity, improved protease resistance, negligible loss or an improvement in binding affinity, and excellent in vivo targeting. The ease of incorporating azidohomoalanine in peptides and efficient reaction with the dialkyne linker enables this technique to potentially be used as a general method for labeling alpha helices. This strategy should be useful for imaging beta cells in diabetes research and in developing and testing other peptide targeting agents. PMID:25594741

  7. On the thermal stability of vacancy-carbon complexes in alpha iron

    NASA Astrophysics Data System (ADS)

    Terentyev, D.; Bonny, G.; Bakaev, A.; Van Neck, D.

    2012-09-01

    In this work we have summarized the available ab initio data addressing the interaction of carbon with vacancy defects in bcc Fe and performed additional calculations to extend the available dataset. Using an ab initio based parameterization, we apply object kinetic Monte Carlo (OKMC) simulations to model the process of isochronal annealing in bcc Fe doped with carbon to compare with experimental data. As a result of this work, we clarify that a binding energy of ˜0.65 eV for a vacancy-carbon (V-C) pair fits the available experimental data best. It is found that the V 2-C complex is less stable than the V-C pair and its dissociation with activation energy of 0.55 + 0.49 eV also rationalizes a number of experimental data where the breakup of V-C complexes was assumed instead. From the summarized ab initio data, the subsequently obtained OKMC results and critical discussion, provided here, we suggest that the twofold interpretation of the V-C binding energy, which is believed to vary between 0.47 and 0.65 eV, depending on the ab initio approximation, should be removed. The stability and mobility of small and presumably immobile SIA clusters formed at stage II is also discussed in the view of experimental data.

  8. Enzyme-polymer composites with high biocatalytic activity and stability

    SciTech Connect

    Kim, Jungbae; Kosto, Timothy J.; Manimala, Joseph C.; Nauman, E B.; Dordick, Jonathan S.

    2004-08-22

    We have applied vacuum-spraying and electrospinning to incorporate an enzyme into a polymer matrix, creating a novel and highly active biocatalytic composite. As a unique technical approach, enzymes were co-dissolved in toluene with polymers, and the solvent was then rapidly removed by injecting the mixture into a vacuum chamber or by electrospinning. Subsequent crosslinking of the enzyme with glutaraldehyde resulted in stable entrapped enzyme within the polymeric matrices. For example, an amorphous composite of alpha-chymotrypsin and polyethylene showed no significant loss of enzymatic activity in aqueous buffer for one month. Nanofibers of alpha-chymotrypsin and polystyrene also showed no decrease in activity for more than two weeks. The normalized activity of amorphous composite in organic solvents was 3-13 times higher than that of native alpha-chymotrypsin. The activity of nanofibers was 5-7 times higher than that of amorphous composite in aqueous buffer solution. The composites of alpha-chymotrypsin and polymers demonstrate the feasibility of obtaining a wide variety of active and stable biocatalytic materials with many combinations of enzymes and polymers.

  9. Control research in the NASA high-alpha technology program

    NASA Technical Reports Server (NTRS)

    Gilbert, William P.; Nguyen, Luat T.; Gera, Joseph

    1990-01-01

    NASA is conducting a focused technology program, known as the High-Angle-of-Attack Technology Program, to accelerate the development of flight-validated technology applicable to the design of fighters with superior stall and post-stall characteristics and agility. A carefully integrated effort is underway combining wind tunnel testing, analytical predictions, piloted simulation, and full-scale flight research. A modified F-18 aircraft has been extensively instrumented for use as the NASA High-Angle-of-Attack Research Vehicle used for flight verification of new methods and concepts. This program stresses the importance of providing improved aircraft control capabilities both by powered control (such as thrust-vectoring) and by innovative aerodynamic control concepts. The program is accomplishing extensive coordinated ground and flight testing to assess and improve available experimental and analytical methods and to develop new concepts for enhanced aerodynamics and for effective control, guidance, and cockpit displays essential for effective pilot utilization of the increased agility provided.

  10. Cretaceous magmatism in the High Canadian Arctic: Implications for the nature and age of Alpha Ridge

    NASA Astrophysics Data System (ADS)

    Bono, Richard; Tarduno, John; Singer, Brad

    2013-04-01

    Cretaceous magmatism in the High Arctic, best expressed on Axel Heiberg and Ellesmere Island, can provide clues to the nature and age of the adjacent Alpha Ridge, which is in turn a key to understanding the tectonic evolution of the Arctic Ocean. Although the incorporation of some continental crust cannot be excluded, the prevailing view is that Alpha Ridge is dominantly thickened oceanic crust, analogous to oceanic plateaus of the Pacific and Indian Ocean. Together with the on-land volcanic exposures, Alpha Ridge composes the High Arctic Large Igneous Province (LIP), but the physical processes responsible for the magmatism remain unclear. Here we focus on two volcanic formations found on the Canadian Arctic margin. The Strand Fiord Formation is composed of a series of classic continental flood basalt flows, and represents the most voluminous expression of volcanism that has survived erosion. These basalts yield a 40Ar/39Ar age of ~95 Ma (Tarduno et al., Science, 1998) but this comes from the distant edge of the flood basalt exposures. The Hansen Point Volcanics consist of felsic and mafic rocks; previous age assignments range from the Maastrichtian (on the basis of palynomorphs, Falcon-Lang et al., Palaeogeography, Palaeoclimatology, Palaeoecology, 2004) to 80 Ma (Rb/Sr isochron, Estrada and Henjes-Kunst, Z. dt. Geol. Ges, 2004). Here we report new 40Ar/39Ar radioisotopic and paleomagnetic data from the Hansen Point Volcanics. In contrast to the latest Cretaceous/Paleogene dates, we find ages of ~95 Ma and 88-90 Ma. Because of the proximity of the landward extension of Alpha Ridge to Hansen Point, these new ages suggest that volcanism that contributed to the construction of Alpha Ridge may have extended over at least a 7 million interval (although it could have occurred in pulses). We will discuss the implications of these new data for candidate mantle processes that could have been responsible for the emplacement of Alpha Ridge and the High Arctic LIP.

  11. Solar absorber material stability under high solar flux

    NASA Astrophysics Data System (ADS)

    Ignatiev, A.; Zajac, G.; Smith, G. B.

    1982-04-01

    Solar absorbing Black Chrome coatings have been exposed to high temperatures (350-400 C) under high solar fluxes (0.4 to 2.0 MW/sq m) to test for their stability under actual operating conditions. Field tests at the White Sands Solar Furnace have shown higher stability than expected from oven tested samples. Laboratory studies utilizing spectrally selective concentrated solar simulated radiation have indicated that the cause of the higher stability under solar irradiation is photo-stimulated desorption of oxygen bearing species at the absorber surface and resultant reduced oxidation of the absorber.

  12. High-Spin Organic Diradical with Robust Stability.

    PubMed

    Gallagher, Nolan M; Bauer, Jackson J; Pink, Maren; Rajca, Suchada; Rajca, Andrzej

    2016-08-01

    Triplet ground-state organic molecules are interesting with respect to several emerging technologies but typically exhibit limited stability. We report two organic diradicals, one of which possesses a triplet ground state (2J/kB = 234 ± 36 K) and robust stability at elevated temperatures. We are able to sublime this high-spin diradical under high vacuum at 140 °C with no significant decomposition. PMID:27430499

  13. Method for high specific bioproductivity of .alpha.,.omega.-alkanedicarboxylic acids

    DOEpatents

    Mobley, David Paul; Shank, Gary Keith

    2000-01-01

    This invention provides a low-cost method of producing .alpha.,.omega.-alkanedicarboxylic acids. Particular bioconversion conditions result in highly efficient conversion of fatty acid, fatty acid ester, or alkane substrates to diacids. Candida tropicalis AR40 or similar yeast strains are grown in a medium containing a carbon source and a nitrogen source at a temperature of 31.degree. C. to 38.degree. C., while additional carbon source is continuously added, until maximum cell growth is attained. Within 0-3 hours of this point, substrate is added to the culture to initiate conversion. An .alpha.,.omega.-alkanedicarboxylic acid made according to this method is also provided.

  14. Method for high specific bioproductivity of {alpha},{omega}-alkanedicarboxylic acids

    SciTech Connect

    Mobley, D.P.; Shank, G.K.

    2000-05-23

    This invention provides a low-cost method of producing {alpha},{omega}-alkanedicarboxylic acids. Particular bioconversion conditions result in highly efficient conversion of fatty acid, fatty acid ester, or alkane substrates to diacids. Candida tropicalis AR40 or similar yeast strains are grown in a medium containing a carbon source and a nitrogen source at a temperature of 31 C to 38 C, while additional carbon source is continuously added, until maximum cell growth is attained. Within 0--3 hours of this point, substrate is added to the culture to initiate conversion. An {alpha},{omega}-alkanedicarboxylic acid made according to this method is also provided.

  15. Decreased specific antibody responses to alpha-Gal-conjugated antigen in animals with preexisting high levels of natural antibodies binding alpha-Gal residues.

    PubMed

    Parmentier, H K; De Vries Reilingh, G; Lammers, A

    2008-05-01

    High levels of natural antibodies (NAb) binding the alpha-Gal residue (Galalpha1-3Galbeta1-4GlcNAc) are found in poultry (and humans), which is probably reflected by high levels of natural agglutinating antibodies (Ab) to rabbit red blood cells (RRBC) in plasma from chickens (and humans). Recently, it was shown that alpha-Gal conjugation of proteins induced higher antiprotein Ab responses in alpha-Gal knockout mice, suggesting immune-enhancing features of preexisting Ab binding carbohydrate-protein conjugates. We challenged chickens s.c. with either alpha-Gal-conjugated human serum albumin (HuSA), beta-Gal-conjugated HuSA, or unconjugated ("native") HuSA, respectively, and measured primary and secondary Ab responses to HuSA, including isotype IgM and IgG responses, and cellular immune responses in vitro (lymphoproliferation) to HuSA or concanavalin A. alpha-Gal conjugation, but not beta-Gal conjugation, of HuSA resulted in significantly decreased primary and secondary Ab responses to HuSA, especially IgG isotype responses, as compared with Ab responses to native HuSA. Lymphoproliferation in vitro was also decreased, although not significantly, in birds challenged with alpha-Gal-conjugated HuSA. High levels of agglutinating Ab levels to RRBC and NAb binding porcine thyroglobulin were detected in all birds, as was true for (natural) Ab levels binding alpha-Gal-conjugated HuSA before immunization, whereas low levels of preexisting (natural) antibodies directed to native HuSA were present in plasma before immunization. Levels of RRBC agglutinins and Ab binding thyroglobulin were not affected by immunization with HuSA, alpha-Gal-conjugated HuSA, or beta-Gal-conjugated HuSA. Our data confirm the presence of high levels of (preexisting) NAb in the plasma of chickens directed to the alpha-Gal residue. The decreased responsiveness to alpha-Gal-bearing antigens in the current study shows that, in addition to immune-enhancing features, NAb may also have suppressive effects on

  16. High Performance BDR for the PCU of AlphaBus

    NASA Astrophysics Data System (ADS)

    Subrier, Laurent; Besdel, Patrick; Daubresse, Thierry; Trehet, Eric

    2008-09-01

    Very high-power satellites for Telecom missions require 100V bus. Some Telecom payloads may be used in TDMA mode with a power modulation up to 30% of the Payload power. Full performance of the PCU is required in this case even in eclipse mode. It is clear that this requirement is very demanding especially for the BDR design.100V bus system leads making this requirement more difficult as Bus and Battery short-circuit protections have to operate under a voltage of 100V. This paper describes first the overall BDR design with a special focus on the innovative battery short-circuit protection that is not achieved by a "classical" series SSPC on the battery line.The constraints brought by the TDMA mode are detailed, especially on the input filter of the BDR in presence of large battery inductance. The solution developed to cope with large TDMA current is then presented with the associated TDMA performance.

  17. In-situ observation of the alpha/beta cristobalite transition using high voltage electron microscopy

    SciTech Connect

    Meike, A.; Glassley, W.

    1989-10-01

    A high temperature water vapor phase is expected to persist in the vicinity of high level radioactive waste packages for several hundreds of years. The authors have begun an investigation of the structural and chemical effects of water on cristobalite because of its abundance in the near field environment. A high voltage transmission electron microscope (HVEM) investigation of bulk synthesized {alpha}-cristobalite to be used in single phase dissolution and precipitation kinetics experiments revealed the presence {beta}-cristobalite, quartz and amorphous silica, in addition to {alpha}-cristobalite. Consequently, this apparent metastable persistence of {beta}-cristobalite and amorphous silica during the synthesis of {alpha}-cristobalite was investigated using a heating stage and an environmental cell installed in the HVEM that allowed the introduction of either dry CO{sub 2} or a CO{sub 2} + H{sub 2}O vapor. Preliminary electron diffraction evidence suggests that the presence of water vapor affected the {alpha}-{beta} transition temperature. Water vapor may also be responsible for the development of an amorphous silica phase at the transition that may persist over an interval of several tens of degrees. The amorphous phase was not documented during the dry heating experiments. 20 refs., 7 figs., 5 tabs.

  18. High efficiency SNAP survey for Lyman alpha emitters at low redshift

    NASA Astrophysics Data System (ADS)

    McCandliss, Stephan

    2014-10-01

    The goal of this proposal is to provide the first statistically significant survey of star-forming galaxies with Lyman alpha emission at redshifts 0.02 < z < 0.24. It will provide an overall assessment of the evolution in Lyman alpha luminosity at the lowest redshifts and allowed detailed studies of the physical processes that shape the Lyman alpha profile and govern escape in multi-phase, kinematic media. It will also provide a serendipitous search for star-forming galaxies with high LyC escape fractions that are analogous to those commonly invoked as being responsible for initiating and sustaining the epoch of reionization. The SNAP survey proposed here employing the G140L mode of COS offers a highly efficient means to examine the Lyman alpha emission properties of our candidate emitters and to inform our choice of objects that could warrant deeper integrations in future observations. These data have high UV legacy value and will be of broad interest to the star-forming galaxy community, so we have elected to waive the proprietary period.

  19. In-flight flow visualization characteristics of the NASA F-18 high alpha research vehicle at high angles of attack

    NASA Technical Reports Server (NTRS)

    Fisher, David F.; Delfrate, John H.; Richwine, David M.

    1991-01-01

    Surface and off-surface flow visualization techniques were used to visualize the 3-D separated flows on the NASA F-18 high alpha research vehicle at high angles of attack. Results near the alpha = 25 to 26 deg and alpha = 45 to 49 deg are presented. Both the forebody and leading edge extension (LEX) vortex cores and breakdown locations were visualized using smoke. Forebody and LEX vortex separation lines on the surface were defined using an emitted fluid technique. A laminar separation bubble was also detected on the nose cone using the emitted fluid technique and was similar to that observed in the wind tunnel test, but not as extensive. Regions of attached, separated, and vortical flow were noted on the wing and the leading edge flap using tufts and flow cones, and compared well with limited wind tunnel results.

  20. Properties of Lyman-alpha Absorbers at High-Redshift

    NASA Astrophysics Data System (ADS)

    Peroux, C.

    2001-09-01

    In recent years, an extremely successful method to observationally study early stages of galaxy formation has been provided by the study of quasar absorbers. Quasar absorption lines are systems intercepting our line-of-sight to a given quasar and thus produce a feature in the quasar spectrum. Damped Lyman-α systems (hereafter DLAs) have N (H I) > 2 × 1020 atoms cm-2, and were originally thought to be the precursors of present day disk galaxies but there is evidence that they may be dominated by gas-rich proto-dwarf galaxies representing the basic building blocks of hierarchical growth of structure. Since their detection is independent of their size, shape, and covering factor, they provide a unbiased method with which to study early galaxies. DLAs are a subset of Lyman-limit Systems (hereafter LLS) which have hydrogen column densities N (H I) > 1.6 × 1017 atoms cm-2. At z < 1, they are probably associated with galactic halos. Finally, the Lyman-α forest is composed of many small column density systems ranging from N (H I) =1012 to 1.6 × 1017 atoms cm-2. This thesis presents a sample of 66 bright z ⪆ 4 quasars observed with the 4 m Cerro Tololo Inter-American Observatory telescope and the 4.2 m William Hershel telescope. The first part of the study concentrates on the quasars themselves via the fitting of quasar continua and the measurement of continuum depression parameters characterising the mean absorption across the Lyman-α forest. The quasar spectra are then analysed to investigate the absorption systems they contain. This led to the discovery of 26 new DLAs, 34 LLS and many associated metal lines which enables the analysis of the evolution of the column density distribution, f(N,z), and the total mass in high-column density neutral hydrogen quasar absorbers. The observed number of LLS per unit redshift is used to constrain f(N,z) below the DLA limit in the range N(HI) = 1.6 × 1017 to 2× 1020 atoms cm-2. The joint analysis shows unambiguously that f

  1. High stability design for new centrifugal compressor

    NASA Technical Reports Server (NTRS)

    Kanki, H.; Katayama, K.; Morii, S.; Mouri, Y.; Umemura, S.; Ozawa, U.; Oda, T.

    1989-01-01

    It is essential that high-performance centrifugal compressors be free of subsynchronous vibrations. A new high-performance centrifugal compressor has been developed by applying the latest rotordynamics knowledge and design techniques: (1) To improve the system damping, a specially designed oil film seal was developed. This seal attained a damping ratio three times that of the conventional design. The oil film seal contains a special damper ring in the seal cartridge. (2) To reduce the destabilizing effect of the labyrinth seal, a special swirl canceler (anti-swirl nozzle) was applied to the balance piston seal. (3) To confirm the system damping margin, the dynamic simulation rotor model test and the full load test applied the vibration exciting test in actual load conditions.

  2. Elimination of the free sulfhydryl group in the human serum albumin (HSA) moiety of human interferon-alpha2b and HSA fusion protein increases its stability against mechanical and thermal stresses.

    PubMed

    Zhao, Hong Liang; Xue, Chong; Wang, Yang; Sun, Bo; Yao, Xue Qin; Liu, Zhi Min

    2009-06-01

    Interferon-alpha2b (IFN-alpha2b) and human serum albumin (HSA) fusion protein (IFN-alpha2b-HSA) is a promising long acting formulation of IFN-alpha2b for the treatment of hepatitis C. However, accelerated mechanical and thermal stress tests revealed that IFN-alpha2b-HSA was prone to disulfide-linked aggregation. The formation of aggregates was associated with an increase in immunogenicity in mice. The addition of non-ionic surfactant Tween 80 increased the stability of IFN-alpha2b-HSA against agitation, but its thermal stability was not improved. Moreover, Tween 80 prompted the aggregation of IFN-alpha2b-HSA during quiescent storage. To increase the stability of IFN-alpha2b-HSA, the unpaired cysteine residue in this fusion protein was substituted with serine by site-directed mutagenesis. The resultant fusion protein was designated as IFN-alpha2b-HSA(C34S). IFN-alpha2b-HSA(C34S) had significant higher stability over IFN-alpha2b-HSA, which was evidenced by the facts that after agitation for 72 h or incubation at 60 degrees C for 2 h, more than 90% of IFN-alpha2b-HSA(C34S) remained monomeric. Consistent with its improved stability, the immunogenicity of IFN-alpha2b-HSA(C34S) increased less significantly after agitation. Pharmacokinetics studies in rats revealed that both fusion proteins had similar pharmacokinetic behavior, both with a half-life of about 50 h. PMID:19462475

  3. Alpha reactivity to first names differs in subjects with high and low dream recall frequency

    PubMed Central

    Ruby, Perrine; Blochet, Camille; Eichenlaub, Jean-Baptiste; Bertrand, Olivier; Morlet, Dominique; Bidet-Caulet, Aurélie

    2013-01-01

    Studies in cognitive psychology showed that personality (openness to experience, thin boundaries, absorption), creativity, nocturnal awakenings, and attitude toward dreams are significantly related to dream recall frequency (DRF). These results suggest the possibility of neurophysiological trait differences between subjects with high and low DRF. To test this hypothesis we compared sleep characteristics and alpha reactivity to sounds in subjects with high and low DRF using polysomnographic recordings and electroencephalography (EEG). We acquired EEG from 21 channels in 36 healthy subjects while they were presented with a passive auditory oddball paradigm (frequent standard tones, rare deviant tones and very rare first names) during wakefulness and sleep (intensity, 50 dB above the subject's hearing level). Subjects were selected as High-recallers (HR, DRF = 4.42 ± 0.25 SEM, dream recalls per week) and Low-recallers (LR, DRF = 0.25 ± 0.02) using a questionnaire and an interview on sleep and dream habits. Despite the disturbing setup, the subjects' quality of sleep was generally preserved. First names induced a more sustained decrease in alpha activity in HR than in LR at Pz (1000–1200 ms) during wakefulness, but no group difference was found in REM sleep. The current dominant hypothesis proposes that alpha rhythms would be involved in the active inhibition of the brain regions not involved in the ongoing brain operation. According to this hypothesis, a more sustained alpha decrease in HR would reflect a longer release of inhibition, suggesting a deeper processing of complex sounds than in LR during wakefulness. A possibility to explain the absence of group difference during sleep is that increase in alpha power in HR may have resulted in awakenings. Our results support this hypothesis since HR experienced more intra sleep wakefulness than LR (30 ± 4 vs. 14 ± 4 min). As a whole our results support the hypothesis of neurophysiological trait differences in high

  4. Alpha reactivity to first names differs in subjects with high and low dream recall frequency.

    PubMed

    Ruby, Perrine; Blochet, Camille; Eichenlaub, Jean-Baptiste; Bertrand, Olivier; Morlet, Dominique; Bidet-Caulet, Aurélie

    2013-01-01

    Studies in cognitive psychology showed that personality (openness to experience, thin boundaries, absorption), creativity, nocturnal awakenings, and attitude toward dreams are significantly related to dream recall frequency (DRF). These results suggest the possibility of neurophysiological trait differences between subjects with high and low DRF. To test this hypothesis we compared sleep characteristics and alpha reactivity to sounds in subjects with high and low DRF using polysomnographic recordings and electroencephalography (EEG). We acquired EEG from 21 channels in 36 healthy subjects while they were presented with a passive auditory oddball paradigm (frequent standard tones, rare deviant tones and very rare first names) during wakefulness and sleep (intensity, 50 dB above the subject's hearing level). Subjects were selected as High-recallers (HR, DRF = 4.42 ± 0.25 SEM, dream recalls per week) and Low-recallers (LR, DRF = 0.25 ± 0.02) using a questionnaire and an interview on sleep and dream habits. Despite the disturbing setup, the subjects' quality of sleep was generally preserved. First names induced a more sustained decrease in alpha activity in HR than in LR at Pz (1000-1200 ms) during wakefulness, but no group difference was found in REM sleep. The current dominant hypothesis proposes that alpha rhythms would be involved in the active inhibition of the brain regions not involved in the ongoing brain operation. According to this hypothesis, a more sustained alpha decrease in HR would reflect a longer release of inhibition, suggesting a deeper processing of complex sounds than in LR during wakefulness. A possibility to explain the absence of group difference during sleep is that increase in alpha power in HR may have resulted in awakenings. Our results support this hypothesis since HR experienced more intra sleep wakefulness than LR (30 ± 4 vs. 14 ± 4 min). As a whole our results support the hypothesis of neurophysiological trait differences in high and

  5. Ligand-independent pathway that controls stability of interferon alpha receptor

    SciTech Connect

    Liu Jianghuai; Plotnikov, Alexander; Banerjee, Anamika; Suresh Kumar, K.G.; Ragimbeau, Josiane; Marijanovic, Zrinka; Baker, Darren P.; Pellegrini, Sandra; Fuchs, Serge Y.

    2008-03-07

    Ligand-specific negative regulation of cytokine-induced signaling relies on down regulation of the cytokine receptors. Down regulation of the IFNAR1 sub-unit of the Type I interferon (IFN) receptor proceeds via lysosomal receptor proteolysis, which is triggered by ubiquitination that depends on IFNAR1 serine phosphorylation. While IFN-inducible phosphorylation, ubiquitination, and degradation requires the catalytic activity of the Tyk2 Janus kinase, here we found the ligand- and Tyk2-independent pathway that promotes IFNAR1 phosphorylation, ubiquitination, and degradation when IFNAR1 is expressed at high levels. A major cellular kinase activity that is responsible for IFNAR1 phosphorylation in vitro does not depend on either ligand or Tyk2 activity. Inhibition of ligand-independent IFNAR1 degradation suppresses cell proliferation. We discuss the signaling events that might lead to ubiquitination and degradation of IFNAR1 via ligand-dependent and independent pathways and their potential physiologic significance.

  6. Stability of several oxide dispersion strengthened alloys and a directionally solidified gamma/gamma prime-alpha eutectic alloy in a thermal gradient

    NASA Technical Reports Server (NTRS)

    Staniek, G.; Whittenberger, J. D.

    1980-01-01

    Thermal gradient testing of three oxide dispersion strengthened alloys (two Ni-base alloys, MA 754 and MA 6000 E, and the Fe-base MA 956) and the directionally solidified eutectic alloy, gamma/gamma prime-alpha, have been conducted. Experiments were carried out with maximum temperatures up to 1200 C and thermal gradients on the order of 100 C/mm. The oxide dispersion strengthened alloys were difficult to test because the thermal stresses promoted crack nucleation and growth; thus the ability of these alloys to maintain a thermal gradient may be limited. The stability of individual fibers in gamma/gamma prime-alpha was excellent; however, microstructural changes were observed in the vicinity of grain boundaries. Similar structures were also observed in isothermally annealed material; therefore thermal gradients do not affect the microstructure of gamma/gamma prime-alpha in any significant manner.

  7. High beta and second stability region transport and stability analysis. Final report

    SciTech Connect

    Hughes, M.H.; Phillps, M.W.; Todd, A.M.M.; Krishnaswami, J.; Hartley, R.

    1992-09-01

    This report describes ideal and resistive studies of high-beta plasmas and of the second stability region. Emphasis is focused on ``supershot`` plasmas in TFIR where MHD instabilities are frequently observed and which spoil their confinement properties. Substantial results are described from the analysis of these high beta poloidal plasmas. During these studies, initial pressure and safety factor profiles were obtained from the TRANSP code, which is used extensively to analyze experimental data. Resistive MBD stability studies of supershot equilibria show that finite pressure stabilization of tearing modes is very strong in these high {beta}p plasmas. This has prompted a detailed re-examination of linear tearing mode theory in which we participated in collaboration with Columbia University and General Atomics. This finite pressure effect is shown to be highly sensitive to small scale details of the pressure profile. Even when an ad hoc method of removing this stabilizing mechanism is implemented, however, it is shown that there is only superficial agreement between resistive MBD stability computation and the experimental data. While the mode structures observed experimentally can be found computationally, there is no convincing correlation with the experimental observations when the computed results are compared with a large set of supershot data. We also describe both the ideal and resistive stability properties of TFIR equilibria near the transition to the second region. It is shown that the highest {beta} plasmas, although stable to infinite-n ideal ballooning modes, can be unstable to the so called ``infernal`` modes associated with small shear. The sensitivity of these results to the assumed pressure and current density profiles is discussed. Finally, we describe results from two collaborative studies with PPPL. The first involves exploratory studies of the role of the 1/1 mode in tokamaks and, secondly, a study of sawtooth stabilization using ICRF.

  8. High-pressure stabilization of argon fluorides.

    PubMed

    Kurzydłowski, Dominik; Zaleski-Ejgierd, Patryk

    2016-01-28

    On account of the rapid development of noble gas chemistry in the past half-century both xenon and krypton compounds can now be isolated in macroscopic quantities. The same does not hold true for the next lighter group 18 element, argon, which forms only isolated molecules stable solely in low temperature matrices or supersonic jet streams. Here we present theoretical investigations into a new high-pressure reaction pathway, which enables synthesis of argon fluorides in bulk and at room temperature. Our hybrid DFT calculations (employing the HSE06 functional) indicate that above 60 GPa ArF2-containing molecular crystals can be obtained by a reaction between argon and molecular fluorine. PMID:26742478

  9. High-resolution measurement of absolute {alpha}-decay widths in {sup 16}O

    SciTech Connect

    Wheldon, C.; Ashwood, N. I.; Barr, M.; Curtis, N.; Freer, M.; Kokalova, Tz.; Malcolm, J. D.; Spencer, S. J.; Ziman, V. A.; Faestermann, Th.; Kruecken, R.; Wirth, H.-F.; Hertenberger, R.; Lutter, R.; Bergmaier, A.

    2011-06-15

    By using a large-acceptance position-sensitive silicon detector array in coincidence with the high-resolution Munich Q3D spectrograph, unambiguous measurements have been made of the absolute {alpha}-particle decay widths from excited states in {sup 16}O* in the energy range 13.85 to 15.87 MeV. Carbon targets have been bombarded with 42-MeV {sup 6}Li beams to induce {sub 6}{sup 12}C({sub 3}{sup 6}Li, d){sub 8}{sup 16}O* reactions. The deuteron ejectiles were measured in the Q3D and the results gated by {sup 4}He+{sup 12}C breakup products detected in the silicon array, the efficiency of which was modeled using Monte Carlo simulations. By comparing total population and breakup-gated spectra, the following absolute {alpha}-decay widths have been measured with high resolution: {Gamma}{sub {alpha}}0/{Gamma}{sub tot} = 0.87{+-}0.11 (13.980 MeV), 1.04{+-}0.15 (14.302 MeV), 0.92{+-}0.10 (14.399 MeV), 0.59{+-}0.04 (14.815 MeV), 0.88{+-}0.18 (15.785 MeV), and {Gamma}{sub {alpha}}1/{Gamma}{sub tot}=1.14{+-}0.08 (14.660 MeV), 0.46{+-}0.06 (14.815 MeV).

  10. Stabilization of Mercury in High pH Tank Sludges

    SciTech Connect

    Spence, R.; Barton, J.

    2003-02-24

    DOE complex contains many tank sludges contaminated with mercury. The high pH of these tank sludges typically fails to stabilize the mercury, resulting in these radioactive wastes also being characteristically hazardous or mixed waste. The traditional treatment for soluble inorganic mercury species is precipitation as insoluble mercuric sulfide. Sulfide treatment and a commercial mercury-stabilizing product were tested on surrogate sludges at various alkaline pH values. Neither the sulfide nor the commercial product stabilized the mercury sufficiently at the high pH of the tank sludges to pass the Toxicity Characteristic Leach Procedure (TCLP) treatment standards of the Resource Conservation and Recovery Act (RCRA). The commercial product also failed to stabilize the mercury in samples of the actual tank sludges.

  11. Effect of nitrogen on the stabilization of austenite in a tungsten-molybdenum high-speed steel

    SciTech Connect

    Popandopulo, A.N.; Zhukova, L.T.

    1986-05-01

    A study was made of the tendency of steels R6M5 and R6Am5 to austenite stabilization after subzero treatment and high-temperature tempering in hot-rolled bars. Data indicate that in steel R6AM5 during quenching there is almost instantaneous austenite stabilization. The data was derived from a study of phase composition (exposure from a microsection in DRON-2.0 equipment in iron K /SUB alpha/ radiation), microstructure, and hardness. The authors conclude that in view of serious difficulties in metallurgical and tool production, steel R6AM5 should be supplied only at the request of the customer.

  12. Thermal stability of high temperature structural alloys

    SciTech Connect

    Jordan, C.E.; Rasefske, R.K.; Castagna, A.

    1999-03-01

    High temperature structural alloys were evaluated for suitability for long term operation at elevated temperatures. The effect of elevated temperature exposure on the microstructure and mechanical properties of a number of alloys was characterized. Fe-based alloys (330 stainless steel, 800H, and mechanically alloyed MA 956), and Ni-based alloys (Hastelloy X, Haynes 230, Alloy 718, and mechanically alloyed MA 758) were evaluated for room temperature tensile and impact toughness properties after exposure at 750 C for 10,000 hours. Of the Fe-based alloys evaluated, 330 stainless steel and 800H showed secondary carbide (M{sub 23}C{sub 6}) precipitation and a corresponding reduction in ductility and toughness as compared to the as-received condition. Within the group of Ni-based alloys tested, Alloy 718 showed the most dramatic structure change as it formed delta phase during 10,000 hours of exposure at 750 C with significant reductions in strength, ductility, and toughness. Haynes 230 and Hastelloy X showed significant M{sub 23}C{sub 6} carbide precipitation and a resulting reduction in ductility and toughness. Haynes 230 was also evaluated after 10,000 hours of exposure at 850, 950, and 1050 C. For the 750--950 C exposures the M{sub 23}C{sub 6} carbides in Haynes 230 coarsened. This resulted in large reductions in impact strength and ductility for the 750, 850 and 950 C specimens. The 1050 C exposure specimens showed the resolution of M{sub 23}C{sub 6} secondary carbides, and mechanical properties similar to the as-received solution annealed condition.

  13. Phosphorylation of 20S proteasome alpha subunit C8 (alpha7) stabilizes the 26S proteasome and plays a role in the regulation of proteasome complexes by gamma-interferon.

    PubMed Central

    Bose, Suchira; Stratford, Fiona L L; Broadfoot, Kerry I; Mason, Grant G F; Rivett, A Jennifer

    2004-01-01

    In animal cells there are several regulatory complexes which interact with 20S proteasomes and give rise to functionally distinct proteasome complexes. gamma-Interferon upregulates three immuno beta catalytic subunits of the 20S proteasome and the PA28 regulator, and decreases the level of 26S proteasomes. It also decreases the level of phosphorylation of two proteasome alpha subunits, C8 (alpha7) and C9 (alpha3). In the present study we have investigated the role of phosphorylation of C8 by protein kinase CK2 in the formation and stability of 26S proteasomes. An epitope-tagged C8 subunit expressed in mammalian cells was efficiently incorporated into both 20S proteasomes and 26S proteasomes. Investigation of mutants of C8 at the two known CK2 phosphorylation sites demonstrated that these are the two phosphorylation sites of C8 in animal cells. Although phosphorylation of C8 was not absolutely essential for the formation of 26S proteasomes, it did have a substantial effect on their stability. Also, when cells were treated with gamma-interferon, there was a marked decrease in phosphorylation of C8, a decrease in the level of 26S proteasomes, and an increase in immunoproteasomes and PA28 complexes. These results suggest that the down-regulation of 26S proteasomes after gamma-interferon treatment results from the destabilization that occurs after dephosphorylation of the C8 subunit. PMID:14583091

  14. The High Frequency Stabilization of a Magnetoplasmadynamic Thruster

    NASA Astrophysics Data System (ADS)

    Kirdyashev, K.

    2004-10-01

    Experimental data on the high-frequency stabilization of the MPD thruster and the suppression of low-frequency oscillations in the frequency range from 20 to 100 kHz are presented. Conditions for the stabilizing effect of a high-frequency magnetic field at the frequency of 40 MHz on the plasma jet produced by the thruster are determined, and the efficiency of this action is evaluated. The action of high frequency field on the MPD thruster consists in the contention of two processes - the stabilization of the plasma drift instability by the magnetic component of high frequency field and the energy conversion of natural plasma oscillations excited by the external field to the ion-sound wave energy.

  15. Stability of Materials in High Temperature Water Vapor: SOFC Applications

    NASA Technical Reports Server (NTRS)

    Opila, E. J.; Jacobson, N. S.

    2010-01-01

    Solid oxide fuel cell material systems require long term stability in environments containing high-temperature water vapor. Many materials in fuel cell systems react with high-temperature water vapor to form volatile hydroxides which can degrade cell performance. In this paper, experimental methods to characterize these volatility reactions including the transpiration technique, thermogravimetric analysis, and high pressure mass spectrometry are reviewed. Experimentally determined data for chromia, silica, and alumina volatility are presented. In addition, data from the literature for the stability of other materials important in fuel cell systems are reviewed. Finally, methods for predicting material recession due to volatilization reactions are described.

  16. Kinetic Stability May Determine the Interaction Dynamics of the Bifunctional Protein DCoH1, the Dimerization Cofactor of the Transcription Factor HNF-1[alpha

    SciTech Connect

    Rho, H.; Jones, C.N.; Rose, R.B.

    2010-12-07

    The two disparate functions of DCoH1 (dimerization cofactor of HNF-1)/PCD (pterin-4a-carbinolamine dehydratase) are associated with a change in oligomeric state. DCoH dimers enhance the activity of the diabetes-associated transcription factor HNF-1{alpha} (hepatocyte nuclear factor-1{alpha}), while the PCD activity of DCoH1 homotetramers aids in aromatic amino acid metabolism. These complexes compete for the same interface of the DCoH dimer. Formation of the DCoH1/HNF-1{alpha} complex requires cofolding. The homotetramer of the DCoH1 paralogue, DCoH2, interacts with HNF-1{alpha} through simple mixing. To further investigate regulation of DCoH/HNF-1{alpha} complex formation, we measured the stability of the DCoH1 homotetramer through unfolding studies by intrinsic tryptophan fluorescence. DCoH2 unfolding is reversible. Surprisingly, the DCoH1 homotetramer is resistant to guanidine unfolding but refolds at a much lower guanidine concentration. We show that a point mutation at the DCoH1 tetramer interface, Thr 51 Ser, overcomes the dissociation barrier of the homotetramer and increases the interaction with HNF-1{alpha}. The 1.8 {angstrom} resolution crystal structure of DCoH1 T51S shows the presence of an ordered water molecule at the tetramer interface, as in DCoH2, which may destabilize the homotetramer. The equilibrium unfolding data were fit to a two-state model with no apparent intermediate. Folding intermediates were detectable by size exclusion chromatography. For wild-type DCoH1 the intermediates changed with time, suggesting a kinetic origin for the unfolding barrier of the homotetramer. We propose an unfolding pathway in which the tetramer unfolds slowly, but the dimer folds reversibly. Implications for regulation of DCoH1/HNF-1{alpha} complex formation are discussed.

  17. Triptolide inhibits COX-2 expression by regulating mRNA stability in TNF-{alpha}-treated A549 cells

    SciTech Connect

    Sun, Lixin; Zhang, Shuang; Jiang, Zhenzhou; Huang, Xin; Wang, Tao; Huang, Xiao; Li, Han; Zhang, Luyong

    2011-12-09

    Highlights: Black-Right-Pointing-Pointer Triptolide inhibited COX-2 expression and the half-life of COX-2 mRNA is decreased. Black-Right-Pointing-Pointer The HuR protein shuttling from nucleus to cytoplasm is inhibited by triptolide. Black-Right-Pointing-Pointer Triptolide inhibited 3 Prime -UTR fluorescence reporter gene activity. Black-Right-Pointing-Pointer COX-2 mRNA binding to HuR is decreased by triptolide in pull-down experiments. -- Abstract: Cyclooxygenase-2 (COX-2) over-expression is frequently associated with human non-small-cell lung cancer (NSCLC) and involved in tumor proliferation, invasion, angiogenesis and resistance to apoptosis. In the present study, the effects of triptolide on COX-2 expression in A549 cells were investigated and triptolide was found to inhibit TNF-{alpha}-induced COX-2 expression. In our further studies, it was found that triptolide decreased the half-life of COX-2 mRNA dramatically and that it inhibited 3 Prime -untranslated region (3 Prime -UTR) fluorescence reporter gene activity. Meanwhile, triptolide inhibited the HuR shuttling from nucleus to cytoplasm. After triptolide treatment, decreased COX-2 mRNA in pull-down experiments with anti-HuR antibodies was observed, indicating that the decreased cytoplasmic HuR is responsible for the decreased COX-2 mRNA. Taken together, our results provided evidence for the first time that triptolide inhibited COX-2 expression by COX-2 mRNA stability modulation and post-transcriptional regulation. These results provide a novel mechanism of action for triptolide which may be important in the treatment of lung cancer.

  18. Piezo-based miniature high resolution stabilized gimbal

    NASA Astrophysics Data System (ADS)

    Karasikov, Nir; Peled, Gal; Yasinov, Roman; Yetkariov, Rita

    2016-05-01

    Piezo motors are characterized by higher mechanical power density, fast response and direct drive. These features are beneficial for miniature gimbals. A gimbal based on such motors was developed. Diameter is 58 mm, weight is 190 grams. The gimbal carries two cameras: a Flir Quark and an HD day camera. The dynamic performance is as high as 3 rad/sec velocity and 100 rad/secΛ2 acceleration. A two axes stabilization algorithm was developed, yielding 80 micro radian stabilization. Further, a panoramic image capture, at a rate of six stabilized field of views per second, was developed. The manuscript reviews the gimbal structure and open architecture, allowing adaptation to other cameras (SWIR etc.), the control algorithm and presents experimental results of stabilization and of panoramic views taken on a vibration platform and on a UAV.

  19. Stabilized High Power Laser for Advanced Gravitational Wave Detectors

    NASA Astrophysics Data System (ADS)

    Willke, B.; Danzmann, K.; Fallnich, C.; Frede, M.; Heurs, M.; King, P.; Kracht, D.; Kwee, P.; Savage, R.; Seifert, F.; Wilhelm, R.

    2006-03-01

    Second generation gravitational wave detectors require high power lasers with several 100W of output power and with very low temporal and spatial fluctuations. In this paper we discuss possible setups to achieve high laser power and describe a 200W prestabilized laser system (PSL). The PSL noise requirements for advanced gravitational wave detectors will be discussed in general and the stabilization scheme proposed for the Advanced LIGO PSL will be described. Special emphasis will be given to the most demanding power stabilization requiremets and new results (RIN <= 4×10-9/surdHz) will be presented.

  20. Controls for agility research in the NASA High-Alpha Technology Program

    NASA Technical Reports Server (NTRS)

    Foster, John V.; Bundick, W. T.; Pahle, Joseph W.

    1991-01-01

    The research process being used to develop control law design methodologies and guidelines in the NASA High-Alpha Technology Program are discussed. This step-by-step process consists of four basic elements: (1) control law architecture definition and linear synthesis, (2) nonlinear batch simulation, (3) piloted simulation evaluation, and (4) flight test validation. This paper discusses the research tools being used in this effort and provides a status report on design methodologies and guidelines being developed for each of these elements.

  1. Governing metal-organic frameworks towards high stability.

    PubMed

    Li, Na; Xu, Jian; Feng, Rui; Hu, Tong-Liang; Bu, Xian-He

    2016-06-30

    Metal-organic frameworks (MOFs) constructed with metal ions/clusters and organic ligands have emerged as an important family of porous materials for various applications. However, the stability of this class of materials is crucial for their practical applications, which might be improved by varying their chemical composition and/or structurally tuning them. To fabricate MOFs with high stability, several strategies for enhancing the stability of MOFs have been developed, in which the strength of metal-ligand bonds is especially considered: the use of highly charged cations and higher pKa ligands, and varying the chemical functionality of linkers. On the other hand, the regulation of their structural architectures is also investigated: interpenetrated frameworks, multi-walled frameworks, and self-strengthening of the frameworks. In addition, the surface modification can also improve the stability of the materials. In this review, we introduce and summarize these strategies from the viewpoint of structural tuning and component choosing, providing useful instructions for the further design and synthesis of MOFs with high-level stability. PMID:27230794

  2. Rapid, automated, parallel quantitative immunoassays using highly integrated microfluidics and AlphaLISA

    PubMed Central

    Tak For Yu, Zeta; Guan, Huijiao; Ki Cheung, Mei; McHugh, Walker M.; Cornell, Timothy T.; Shanley, Thomas P.; Kurabayashi, Katsuo; Fu, Jianping

    2015-01-01

    Immunoassays represent one of the most popular analytical methods for detection and quantification of biomolecules. However, conventional immunoassays such as ELISA and flow cytometry, even though providing high sensitivity and specificity and multiplexing capability, can be labor-intensive and prone to human error, making them unsuitable for standardized clinical diagnoses. Using a commercialized no-wash, homogeneous immunoassay technology (‘AlphaLISA’) in conjunction with integrated microfluidics, herein we developed a microfluidic immunoassay chip capable of rapid, automated, parallel immunoassays of microliter quantities of samples. Operation of the microfluidic immunoassay chip entailed rapid mixing and conjugation of AlphaLISA components with target analytes before quantitative imaging for analyte detections in up to eight samples simultaneously. Aspects such as fluid handling and operation, surface passivation, imaging uniformity, and detection sensitivity of the microfluidic immunoassay chip using AlphaLISA were investigated. The microfluidic immunoassay chip could detect one target analyte simultaneously for up to eight samples in 45 min with a limit of detection down to 10 pg mL−1. The microfluidic immunoassay chip was further utilized for functional immunophenotyping to examine cytokine secretion from human immune cells stimulated ex vivo. Together, the microfluidic immunoassay chip provides a promising high-throughput, high-content platform for rapid, automated, parallel quantitative immunosensing applications. PMID:26074253

  3. Rapid, automated, parallel quantitative immunoassays using highly integrated microfluidics and AlphaLISA

    NASA Astrophysics Data System (ADS)

    TakYu, Zeta; Guan, Huijiao; Ki Cheung, Mei; McHugh, Walker M.; Cornell, Timothy T.; Shanley, Thomas P.; Kurabayashi, Katsuo; Fu, Jianping

    2015-06-01

    Immunoassays represent one of the most popular analytical methods for detection and quantification of biomolecules. However, conventional immunoassays such as ELISA and flow cytometry, even though providing high sensitivity and specificity and multiplexing capability, can be labor-intensive and prone to human error, making them unsuitable for standardized clinical diagnoses. Using a commercialized no-wash, homogeneous immunoassay technology (‘AlphaLISA’) in conjunction with integrated microfluidics, herein we developed a microfluidic immunoassay chip capable of rapid, automated, parallel immunoassays of microliter quantities of samples. Operation of the microfluidic immunoassay chip entailed rapid mixing and conjugation of AlphaLISA components with target analytes before quantitative imaging for analyte detections in up to eight samples simultaneously. Aspects such as fluid handling and operation, surface passivation, imaging uniformity, and detection sensitivity of the microfluidic immunoassay chip using AlphaLISA were investigated. The microfluidic immunoassay chip could detect one target analyte simultaneously for up to eight samples in 45 min with a limit of detection down to 10 pg mL-1. The microfluidic immunoassay chip was further utilized for functional immunophenotyping to examine cytokine secretion from human immune cells stimulated ex vivo. Together, the microfluidic immunoassay chip provides a promising high-throughput, high-content platform for rapid, automated, parallel quantitative immunosensing applications.

  4. High temperature stability of lanthanum silicate dielectric on Si (001)

    SciTech Connect

    Jur, J. S.; Lichtenwalner, D. J.; Kingon, A. I.

    2007-03-05

    Integration of a high-{kappa} dielectric into complementary metal-oxide-semiconductor devices requires thermal stability of the amorphous dielectric phase and chemical compatibility with silicon. The stability of amorphous lanthanum silicate on Si (001) is investigated by means of metal-insulator-semiconductor capacitor measurements, back side secondary ion mass spectrometry (SIMS) depth profiling, and high-resolution transmission electron microscopy (HRTEM) after a 1000 deg. C, 10 s anneal in nitrogen ambient. Back side SIMS depth profiling of the TaN/LaSiO{sub x}/Si gate stack reveals no detectable lanthanum in the silicon substrate, and HRTEM shows stability of the amorphous LaSiO{sub x}. An effective work function near 4.0 eV is obtained for these gate stacks, making the stack design ideal for n-type metal-oxide-semiconductor device fabrication.

  5. High Stability Engine Control (HISTEC) Flight Test Results

    NASA Technical Reports Server (NTRS)

    Southwick, Robert D.; Gallops, George W.; Kerr, Laura J.; Kielb, Robert P.; Welsh, Mark G.; DeLaat, John C.; Orme, John S.

    1998-01-01

    The High Stability Engine Control (HISTEC) Program, managed and funded by the NASA Lewis Research Center, is a cooperative effort between NASA and Pratt & Whitney (P&W). The program objective is to develop and flight demonstrate an advanced high stability integrated engine control system that uses real-time, measurement-based estimation of inlet pressure distortion to enhance engine stability. Flight testing was performed using the NASA Advanced Controls Technologies for Integrated Vehicles (ACTIVE) F-15 aircraft at the NASA Dryden Flight Research Center. The flight test configuration, details of the research objectives, and the flight test matrix to achieve those objectives are presented. Flight test results are discussed that show the design approach can accurately estimate distortion and perform real-time control actions for engine accommodation.

  6. Fusion alpha-particle losses in a high-beta rippled tokamak

    SciTech Connect

    Bunno, M.; Nakamura, Y.; Suzuki, Y.; Shinohara, K.; Matsunaga, G.; Tani, K.

    2013-08-15

    In tokamak plasmas, the confinement of energetic ions depends on the magnetic field structure. If the plasma pressure is finite, the equilibrium current (i.e., the Pfirsch-Schlüter current and diamagnetic current) flows in the plasma to maintain the magnetohydrodynamic (MHD) equilibrium. These plasma currents generate poloidal and toroidal magnetic field and alter the field structure. Moreover, if we consider the non-axisymmetry of magnetic field structures such as toroidal field (TF) ripples, the non-axisymmetric component of the equilibrium current can alter TF ripples themselves. When the plasma beta becomes high, the changes in the field structure due to the equilibrium current might affect the confinement of energetic ions significantly. We intend to clarify how these currents alter the field structure and affect the confinement of alpha particles in high-beta plasma. The MHD equilibrium is calculated using VMEC and the orbits of fusion alpha particles are followed by using the fully three-dimensional magnetic field orbit-following Monte Carlo code. In relatively low-beta plasma (e.g., the volume-averaged beta value <β>≤2%), the changes in the magnetic field component due to the plasma current negligibly affect the confinement of alpha particles except for the Shafranov shift effect. However, for <β>≥3%, the diamagnetic effect reduces the magnetic field strength and significantly increases alpha-particle losses. In these high-beta cases, the non-axisymmetric field component generated by the equilibrium current also increases these losses, but not as effectively as compared to the diamagnetic effect.

  7. Research flight-control system development for the F-18 high alpha research vehicle

    NASA Technical Reports Server (NTRS)

    Pahle, Joseph W.; Powers, Bruce; Regenie, Victoria; Chacon, Vince; Degroote, Steve; Murnyak, Steven

    1991-01-01

    The F-18 high alpha research vehicle was recently modified by adding a thrust vectoring control system. A key element in the modification was the development of a research flight control system integrated with the basic F-18 flight control system. Discussed here are design requirements, system development, and research utility of the resulting configuration as an embedded system for flight research in the high angle of attack regime. Particular emphasis is given to control system modifications and control law features required for high angle of attack flight. Simulation results are used to illustrate some of the thrust vectoring control system capabilities and predicted maneuvering improvements.

  8. EXTENDED Ly{alpha} EMISSION FROM INTERACTING GALAXIES AT HIGH REDSHIFTS

    SciTech Connect

    Yajima, Hidenobu; Li Yuexing; Zhu Qirong

    2013-08-20

    Recent observations have discovered a population of extended Ly{alpha} sources, dubbed Ly{alpha} blobs (LABs), at high redshift z {approx} 2-6.6. These LABs typically have a luminosity of L {approx} 10{sup 42}-10{sup 44} erg s{sup -1}, and a size of tens of kiloparsecs, with some giant ones reaching up to D {approx} 100 kpc. However, the origin of these LABs is not well understood. In this paper, we investigate a merger model for the formation of LABs by studying Ly{alpha} emission from interacting galaxies at high redshifts by means of a combination of hydrodynamics simulations with three-dimensional radiative transfer calculations. Our galaxy simulations focus on a set of binary major mergers of galaxies with a mass range of 3-7 Multiplication-Sign 10{sup 12} M{sub Sun} in the redshift range z {approx} 3-7, and we use the newly improved ART{sup 2} code to perform the radiative transfer calculations, which couple multi-wavelength continuum, ionization of hydrogen, and Ly{alpha} line emission. We find that intense star formation and enhanced cooling induced by gravitational interaction produce strong Ly{alpha} emission from these merging galaxies. The Ly{alpha} emission appears to be extended due to the extended distribution of sources and gas. During the close encounter of galaxy progenitors when the star formation rate peaks at {approx}10{sup 3} M{sub Sun} yr{sup -1}, our model produces LABs with luminosity of L {approx} 10{sup 42}-10{sup 44} erg s{sup -1}, and size of D {approx} 10-20 kpc at z > 6 and D {approx} 20-50 kpc at z {approx} 3, in broad agreement with observations in the same redshift range. Our results suggest that merging galaxies may produce some typical LABs as observed, but the giant ones may be produced by mergers more massive than those in our model, or a combination of mergers and cold accretion from filaments on a large scale.

  9. High structural stability of single wall carbon nanotube under quasi-hydrostatic high pressures

    NASA Astrophysics Data System (ADS)

    Chen, Jing-Yin; Kim, Minseob; Yoo, Choong-Shik

    2009-09-01

    In quasi-hydrostatic conditions, single wall carbon nanotubes (SWNTs) exhibit high structural stability to ˜35 GPa, well beyond the stability of sp2 C dbnd C bonds in graphite, carbon fullerenes, benzene, and other hydrocarbons. The pressure-induced Raman changes of SWNT are completely reversible below 16 GPa, partially reversible between 16 and 35 GPa, and irreversible beyond 35 GPa where it turns into highly disordered graphite. We explain the high stability in terms of the pressure-induced structural modification to an interlinked configuration, which occurs reversibly under substantial sp3 hybridization (˜20%) and, thus, increases the stability of sp2 C dbnd C bonds in the SWNTs.

  10. 20-100 keV K(alpha) X-Ray Source Generation by Short Pulse High Intensity Lasers

    SciTech Connect

    Park, H-S; Koch, J A; Landen, O L; Phillips, T W; Goldsack, T

    2003-08-22

    We are studying the feasibility of utilizing K{alpha} x-ray sources in the range of 20 to 100 keV as a backlighters for imaging various stages of implosions and high areal density planar samples driven by the NIF laser facility. The hard x-ray K{alpha} sources are created by relativistic electron plasma interactions in the target material after a radiation by short pulse high intensity lasers. In order to understand K{alpha} source characteristics such as production efficiency and brightness as a function of laser parameters, we have performed experiments using the 10 J, 100 fs JanUSP laser. We utilized single-photon counting spectroscopy and x-ray imaging diagnostics to characterize the K{alpha} source. We find that the K{alpha} conversion efficiency from the laser energy is {approx} 3 x 10{sup -4}.

  11. Development of scintillator plates with high energy resolution for alpha particles made of GPS scintillator grains

    NASA Astrophysics Data System (ADS)

    Shimaoka, Takehiro; Kaneko, Junichi H.; Izaki, Kenji; Tsubota, Youichi; Higuchi, Mikio; Nishiyama, Shusuke

    2014-01-01

    A scintillator plate with high energy resolution was developed to produce an alpha particle monitor used in nuclear fuel reprocessing plants and mixed plutonium-uranium oxide (MOX) fuel plants. Grains of a Gd2Si2O7 (GPS) scintillator of several 10 to 550 μm were fixed on a glass substrate and were then mechanically polished. By increasing the size of scintillator grains and removing fine powders, the collected light yield and energy resolution for alpha particles were drastically improved. Energy resolution of 9.3% was achieved using average grain size of 91 μm. Furthermore, the ratios between counts in a peak and total counts were improved by more than 60% by the further increase of grain size and adoption of mechanically polished surfaces on both sides. Beta and gamma ray influences were suppressed sufficiently by the thin 100 μm scintillator plates.

  12. Ultra-high-resolution alpha spectrometry for nuclear forensics and safeguards applications

    SciTech Connect

    Bacrania, Minesh K; Croce, Mark; Bond, Evelyn; Dry, Donald; Moody, W. Allen; Lamont, Stephen; Rabin, Michael; Rim, Jung; Smith, Audrey; Beall, James; Bennett, Douglas; Kotsubo, Vincent; Horansky, Robert; Hilton, Gene; Schmidt, Daniel; Ullom, Joel; Cantor, Robin

    2010-01-01

    We will present our work on the development of ultra-high-resolution detectors for alpha particle spectrometry. These detectors, based on superconducting transition-edge sensors, offer energy resolution that is five to ten times better than conventional silicon detectors. Using these microcalorimeter detectors, the isotopic composition of mixed-actinide samples can be determined rapidly without the need for actinide separation chemistry to isolate each element, or mass spectrometry to separate isotopic signatures that can not be resolved using traditional alpha spectrometry (e.g. Pu-239/Pu-240, or Pu-238/Am-241). This paper will cover the detector and measurement system, actinide source preparation, and the quantitative isotopic analysis of a number of forensics- and safeguards-relevant radioactive sources.

  13. Dimensional stability of high-purity Invar 36

    NASA Astrophysics Data System (ADS)

    Sokolowski, Witold M.; Jacobs, Stephen F.; Lane, Marc S.; O'Donnell, Timothy P.; Hsieh, Cheng

    1993-12-01

    High performance requirements for the Imaging Science Subsystem/Narrow Angle Camera (NAC) instrument on the NASA/Jet Propulsion Laboratory (JPL) Cassini spacecraft impose very stringent demands for dimensional stability of metering rods in the camera's athermalizing system. Invar 36 was chosen as a baseline material because it possibly could meet these requirements through high purity control and appropriate thermomechanical processes. A powder metallurgy process appears to be the manufacturing method to ensure high purity and cleanliness of this material. Therefore, a powder metallurgy manufacturer was contacted and high purity (HP) Invar 36 was produced per JPL engineering requirements. Several heat treatments were established and heat treated HP Invar 36 samples were evaluated. Coefficient of thermal expansion (CTE), thermal hysteresis and temporal stability test results are reported here. The test results indicate that JPL has succeeded in obtaining possibly the most dimensionally stable (lowest CTE plus lowest temporal change) Invar 36 material ever produced. CTE < 1 ppm/ degree(s)C are reported here along with temporal stability < 1 ppm/year. These dimensional stability properties will meet the requirements for metering rods on the NAC.

  14. Short-term stability of high-silica glasses

    NASA Technical Reports Server (NTRS)

    Leiser, D. B.

    1981-01-01

    The devitrification characteristics of high-silica (70-90%) glasses for use in potential higher temperature coatings on advanced insulation systems for space vehicles were determined at 1260 C after 24 h. These data indicate that additives can be used to maintain the stability of these coatings relative to cristobalite formation.

  15. Assessment of physical and antioxidant activity stability, in vitro release and in vivo efficacy of formulations added with superoxide dismutase alone or in association with alpha-tocopherol.

    PubMed

    Di Mambro, Valéria Maria; Fonseca, Maria José Vieira

    2007-06-01

    A topical formulation was added with different concentrations of superoxide dismutase (SOD) alone or in association with alpha-tocopherol (alpha-TOC). The physical stability was evaluated by rheological behavior of formulations stored at 4 degrees C, 30 degrees C/60% RH and 40 degrees C/70% RH for 6 months. SOD alone and formulations containing SOD 0.2%, 0.4% or 0.6% or SOD and alpha-TOC were stored in the same conditions and the enzymatic activity was evaluated by the superoxide anion scavenging using chemiluminescence measurement. In vitro release study was carried out using modified Franz diffusion cell and SOD formulations photoprotection against skin erythema was observed for 72 h. SOD and alpha-TOC formulation proved to be instable, since the interaction between the antioxidants led to both physical and enzymatic activity instability. SOD formulations showed to be physically stable and maintained the enzymatic activity for 6 months when stored at 4 and 30 degrees C/60% RH. Despite the fact of low SOD release from the formulation, it was effective in inhibiting the UVB-induced skin erythema for 48 h after a single application. Topical administration of antioxidants provides an efficient way to enrich the endogenous cutaneous protection system, and SOD formulations could be used for improving photoprotection of skin. PMID:17196809

  16. Interaction of a near-{alpha} type titanium alloy with NiCrAlY protective coating at high temperatures

    SciTech Connect

    Liu, H.; Hao, S.; Wang, X.; Feng, Z.

    1998-10-13

    MCrAlY coatings possess the properties of not only excellent oxidation and hot corrosion resistance but also sufficient toughness. This is why they have been commercially used on superalloys for several decades. Nevertheless, investigations revealed that there might be violent interactions between this kind of coating and titanium based alloys at high temperatures. This chemical incompatibility may promote the growth of brittle phases along the substrate/coating interface and thus deteriorates the mechanical properties. An effective barrier layer was desired to be sandwiched between the MCrAlY coating and Ti substrate to weaken the interdiffusion and chemical reactions. Ti60 is a near {alpha} type alloy intended to be used at 600 C. The interaction between this alloy and a NiCrAlY coating has never been investigated. Actually, in addition to the service at high temperature, another high temperature process, i.e., the post heat treatment in vacuum, is generally needed for the MCrAlY coating to eliminate possible defects within the received PVD coatings. Hence, the investigation on the interfacial stability of a Ti60/MCrAlY system at high temperatures is of importance in both theoretical and practical meanings. This paper is aimed at observing the interfacial reactions of this system at various temperatures in excess of 600 C. The obtained data may be useful in further work on optimizing the post treatment parameters and developing new coating systems with barrier interlayer.

  17. A highly sensitive biosensor for tumor maker alpha fetoprotein based on poly(ethylene glycol) doped conducting polymer PEDOT.

    PubMed

    Cui, Min; Song, Zhiling; Wu, Yumin; Guo, Bing; Fan, Xiaojian; Luo, Xiliang

    2016-05-15

    Biocompatible polymers, such as poly(ethylene glycol) (PEG), are of great significance in the development of bio-interfaces and biosensors, as they possess excellent biocompatibility and are easy for modification. A novel highly biocompatible polymer composite was synthesized herein through electrochemical polymerization of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and a PEG derivative, 4-arm PEG terminated with thiol groups. The electrodeposited conducting polymer composite of PEG doped PEDOT (PEDOT/PEG) exhibited flake-like nanostructure, large surface area and outstanding stability. In order to further immobilize antibodies, gold nanoparticles (AuNPs) were introduced to the PEDOT/PEG composite surface through their unique interaction with the thiol groups. AuNPs modified PEDOT/PEG provided a desirable support for the immobilization of various biomolecules such as antibodies for alpha fetoprotein (AFP), a vital tumor biomarker for liver cancer. The fabricated AFP biosensor demonstrated favorable selectivity, high sensitivity, and ultralow detection limit. Furthermore, owing to the presence of PEG polymers that are highly hydrophilic, such AuNPs/PEDOT/PEG based AFP biosensor also exhibited good anti-fouling ability, and it was capable of assaying target AFP in 10% (V/V) human serum samples, indicating highly feasible potential for clinical diagnosis. PMID:26774088

  18. Stability and nesting of dissipative vortex solitons with high vorticity

    NASA Astrophysics Data System (ADS)

    Aleksić, B. N.; Aleksić, N. B.; Skarka, V.; Belić, M.

    2015-04-01

    Using the variational method extended to dissipative systems and numerical simulations, an analytical stability criterion is established allowing the determination of stability domains of parameters for vortices with high topological charge S. Parameters from these domains are used as inputs for numerical self-generation of previously unexplored coexisting stable vortex solitons with topological charge ranging from S =3 to S =20 . The nesting of low-vorticity solitons within those of higher vorticity is discovered. Such a self-organized structuring of light allows for selective dynamic nanophotonic tweezing.

  19. Observation of two-{alpha} emission from high-lying excited states of {sup 18}Ne by complete-kinematics measurements

    SciTech Connect

    Xu, X. X.; Lin, C. J.; Jia, H. M.; Yang, F.; Jia, F.; Wu, Z. D.; Zhang, S. T.; Liu, Z. H.; Zhang, H. Q.; Xu, H. S.; Sun, Z. Y.; Wang, J. S.; Hu, Z. G.; Wang, M.; Chen, R. F.; Zhang, X. Y.; Li, C.; Lei, X. G.; Xu, Z. G.; Xiao, G. Q.

    2010-12-15

    Two-{alpha} emission from high-lying excited states of {sup 18}Ne was studied by complete-kinematics measurements. The {sup 18}Ne beam at the energy of 51.8 MeV/u was bombarding a {sup 197}Au target to populate the excited states via Coulomb excitation. Products of two-{alpha} emission, {sup 10}C-{alpha}-{alpha}, were measured by an array of silicon strip detectors and a CsI + PIN telescope. With the help of Monte Carlo simulations, the experimental results show the characteristics of sequential two-{alpha} emission via {sup 14}O excited states. Sequential two-{alpha} and two-proton emissions from {sup 18}Ne via one-particle daughter states are compared and the distinction of the opening angles of these two modes originates from the difference of the mass ratio of emitted particles to daughter nuclei.

  20. Design guidelines for high dimensional stability of CFRP optical bench

    NASA Astrophysics Data System (ADS)

    Desnoyers, Nichola; Boucher, Marc-André; Goyette, Philippe

    2013-09-01

    In carbon fiber reinforced plastic (CFRP) optomechanical structures, particularly when embodying reflective optics, angular stability is critical. Angular stability or warping stability is greatly affected by moisture absorption and thermal gradients. Unfortunately, it is impossible to achieve the perfect laminate and there will always be manufacturing errors in trying to reach a quasi-iso laminate. Some errors, such as those related to the angular position of each ply and the facesheet parallelism (for a bench) can be easily monitored in order to control the stability more adequately. This paper presents warping experiments and finite-element analyses (FEA) obtained from typical optomechanical sandwich structures. Experiments were done using a thermal vacuum chamber to cycle the structures from -40°C to 50°C. Moisture desorption tests were also performed for a number of specific configurations. The selected composite material for the study is the unidirectional prepreg from Tencate M55J/TC410. M55J is a high modulus fiber and TC410 is a new-generation cyanate ester designed for dimensionally stable optical benches. In the studied cases, the main contributors were found to be: the ply angular errors, laminate in-plane parallelism (between 0° ply direction of both facesheets), fiber volume fraction tolerance and joints. Final results show that some tested configurations demonstrated good warping stability. FEA and measurements are in good agreement despite the fact that some defects or fabrication errors remain unpredictable. Design guidelines to maximize the warping stability by taking into account the main dimensional stability contributors, the bench geometry and the optical mount interface are then proposed.

  1. A HIGH STABILITY, LOW NOISE RF DISTRIBUTION SYSTEM

    SciTech Connect

    Bernstein, Dorel

    2002-08-20

    Next generation linear colliders require high stability, low noise distribution of RF phase and timing signals. We describe a fiber-optics system that transmits phase at 357MHz, at a 1500nm wavelength, over a distance of 15 kilometers. Phase length errors in the transmission fiber are measured using the phase of the signal reflected from the fiber end. Corrections are performed by controlling the temperature of a 6-kilometer fiber spool placed in series with the main transmission fiber. This system has demonstrated a phase stability better than 10 femtoseconds per degree C, per kilometer, an improvement of a factor of >2000 relative to un-stabilized fiber. This system uses standard low cost telecom fiber and components.

  2. Stabilization of high mercury contaminated brine purification sludge.

    PubMed

    Zhuang, J Ming; Lo, Tony; Walsh, Tony; Lam, Tak

    2004-09-10

    The highly leachable mercury contaminants of brine purification sludge (BPS) generated from the Hg-cell electrolysis process in chlorine production can be stabilized in the treatment procedure employing ferric-lignin derivatives (FLD) (Ligmet binder) and Portland cement (PC). The stabilization effectiveness has been examined by time-based multiple toxicity characteristic leaching procedure (TCLP) tests and sequential TCLP tests. In a period of 50 days, the multiple TCLP tests showed a variation of less than 90 microg l(-1) for the leachable mercury level, and the sequential TCLP tests for the same sample displayed a declining TCLP mercury level. Based on this study, the stabilization of approximately 2000 t of brine purification sludge has been successfully processed with the ferric-lignin derivatives treatment. PMID:15363526

  3. Application of high-alpha control system concepts to a variable-sweep fighter airplane

    NASA Technical Reports Server (NTRS)

    Nguyen, L. T.; Gilbert, W. P.; Gera, J.; Iliff, K. W.; Enevoldson, E. K.

    1980-01-01

    The use of control system design to enhance high-angle-of-attack flying qualities and departure/spin resistance has become an accepted and widely used approach for modern fighter aircraft. NASA and the Navy are currently conducting a joint research program to investigate the application of this technology to the F-14. The paper discusses the results of this program within the context of its contributions to advancing high-alpha control system technology. General topics covered include (1) analysis and design tools, (2) control system design approach, and (3) flight test approach and results.

  4. Stability of Trace Gases in High-Pressure Cylinders

    NASA Astrophysics Data System (ADS)

    Hall, B. D.; Montzka, S. A.; Novelli, P. C.; Dutton, G. S.; Elkins, J. W.

    2001-12-01

    Long-term observations of atmospheric trace gases require calibration methods that are consistent and reproducible over the duration of the observations. Small trends in calibration can be difficult to detect, and can mask or alter the apparent atmospheric trends. Trace gas standards in high-pressure cylinders are often used for the calibration of gas chromatographic instruments employed for long-term monitoring, as well as for the collection of archive air samples. We have studied the stability of part-per-million-, part-per-billion-, and part-per-trillion-level gas mixtures (in air) in aluminum and stainless steel cylinders. The stability of a particular compound depends on the type and size of the cylinder, the passivation method employed, and the pressure of the gas in the cylinder. We will report on stability studies involving mixtures of methyl halides, chlorinated solvents, nitrous oxide (N2O), sulfur hexafluoride (SF6), carbon monoxide (CO), and carbonyl sulfide (COS). Methyl halides (CH3Cl and CH3Br) appear to be more stable in stainless steel than in aluminum cylinders. N2O and SF6 show good stability in both types of cylinders. CO tends to increase with time in aluminum cylinders. The stability of CO may improve with higher volume to surface area ratio, but further testing is required. Some chlorinated solvents, such as CH3CCl3, decrease rapidly in non-passivated aluminum cylinders, but can be stable in passivated aluminum and stainless steel cylinders.

  5. Summary of Inlet Characteristics of the F/A-18A High Alpha Research Vehicle

    NASA Technical Reports Server (NTRS)

    Walsh, Kevin; Steenken, William; Williams, John

    1998-01-01

    Effects of high-angle-of-attack flight on aircraft inlet aerodynamic characteristics were investigated at NASA Dryden Flight Research Center as part of NASA's High Alpha Technology Program. The highly instrumented F/A-18A High Alpha Research Vehicle was used for this research. A newly designed inlet total-pressure rake was installed in front of the right-hand F404-GE-400 engine to measure inlet recovery and distortion characteristics. Objectives included: (1) determining the inlet total-pressure characteristics at steady high-angle-of-attack conditions; (2) assessing if inlet distortion is significantly different between rapid angle-of-attack maneuvers and corresponding steady aerodynamic conditions; (3) assessing inlet characteristics during aircraft departures; (4) providing data for developing and verifying computational fluid dynamic codes; and (5) calculating engine airflow using four methods for comparison with a reference method. This paper describes the results obtained from this investigation. These data and the associated database were rigorously validated to establish the foundation for understanding inlet characteristics at high angle of attack.

  6. Computational Investigation of an F-18 Aircraft in the High-Alpha Regime

    NASA Technical Reports Server (NTRS)

    Murman, Scott M.; Rizk, Yehia M.; Kutler, Paul (Technical Monitor)

    1994-01-01

    One of the goals of NASA's High Alpha Technology Program is to provide flight-validated design methods for the high-angle-of-attack regime. This is an integrated effort utilizing computational simulations, wind tunnel experiments, and flight tests using the F-18 High Alpha Research Vehicle (HARV). The dominant physics of the aircraft flows in the high alpha regime changes as the angle of attack is increased. At moderate angle of attack the flow is characterized by boundary layer separation and the formation of tight vortices. As the angle of attack is increased, these vortices break down producing unsteady wakes. With further increase in angle of attack, the, vortex breakdown moves progressively upstream until the entire flowfield becomes dominated by the unsteady wake. Previous computational work has demonstrated the ability to simulate flows about the F-18 HARV in the medium-to-high angle of attack range, where the flowfield is characterized by the vortex formation and subsequent breakdown. This paper extends the previous computations to include conditions of 45 degree angle of attack where the flowfield becomes dominated by the unsteady wake shed from the Leading Edge Extension (LEX), and regions of laminar and transitional flow appear on the fuselage forebody. A more complete surface geometry is utilized, which includes the features of the engine nacelle, inlet diffuser, and the boundary layer diverter duct. A volume grid sensitivity study was also performed to extend the accuracy of the results, most notably in the prediction of the LEX vortex breakdown position. This paper includes comparisons of computational results with both in-flight surface pressure measurements, and flow visualizations of the surface and off-surface particle trajectories.

  7. Analytical aerodynamic model of a high alpha research vehicle wind-tunnel model

    NASA Technical Reports Server (NTRS)

    Cao, Jichang; Garrett, Frederick, Jr.; Hoffman, Eric; Stalford, Harold

    1990-01-01

    A 6 DOF analytical aerodynamic model of a high alpha research vehicle is derived. The derivation is based on wind-tunnel model data valid in the altitude-Mach flight envelope centered at 15,000 ft altitude and 0.6 Mach number with Mach range between 0.3 and 0.9. The analytical models of the aerodynamics coefficients are nonlinear functions of alpha with all control variable and other states fixed. Interpolation is required between the parameterized nonlinear functions. The lift and pitching moment coefficients have unsteady flow parts due to the time range of change of angle-of-attack (alpha dot). The analytical models are plotted and compared with their corresponding wind-tunnel data. Piloted simulated maneuvers of the wind-tunnel model are used to evaluate the analytical model. The maneuvers considered are pitch-ups, 360 degree loaded and unloaded rolls, turn reversals, split S's, and level turns. The evaluation finds that (1) the analytical model is a good representation at Mach 0.6, (2) the longitudinal part is good for the Mach range 0.3 to 0.9, and (3) the lateral part is good for Mach numbers between 0.6 and 0.9. The computer simulations show that the storage requirement of the analytical model is about one tenth that of the wind-tunnel model and it runs twice as fast.

  8. High beta and second stability region transport and stability analysis. Technical progress report

    SciTech Connect

    Hughes, M.H.; Phillps, M.W.; Tood, A.M.M.

    1993-12-01

    This report describes both ideal and resistive MHD stability studies of supershot plasmas in TFTR. The MHD equilibrium and stability modeling of TFTR plasmas has concentrated on those experiments where the safety factor, q, profile was inferred from motional Stark effect measurements (MSE). These are conveniently divided into two groups, first where q is less than unity over some fraction of the plasma radius and, secondly, where q everywhere exceed unity. In the first case, the experimental result that ql we revisit the resistive stability properties of low {beta}, high q{sub edge} supershots again using MSE q-profiles as a starting point. We find that 2/1 and 3/2 tearing modes can be excited in some circumstances and that the MSE profiles are typically near marginal stability to each of these modes.

  9. Alpha-1 giardin is an annexin with highly unusual calcium-regulated mechanisms.

    PubMed

    Weeratunga, Saroja K; Osman, Asiah; Hu, Nien-Jen; Wang, Conan K; Mason, Lyndel; Svärd, Staffan; Hope, Greg; Jones, Malcolm K; Hofmann, Andreas

    2012-10-19

    Alpha-giardins constitute the annexin proteome (group E annexins) in the intestinal protozoan parasite Giardia and, as such, represent the evolutionary oldest eukaryotic annexins. The dominance of alpha-giardins in the cytoskeleton of Giardia with its greatly reduced actin content emphasises the importance of the alpha-giardins for the structural integrity of the parasite, which is particularly critical in the transformation stage between cyst and trophozoite. In this study, we report the crystal structures of the apo- and calcium-bound forms of α1-giardin, a protein localised to the plasma membrane of Giardia trophozoites that has recently been identified as a vaccine target. The calcium-bound crystal structure of α1-giardin revealed the presence of a type III site in the first repeat as known from other annexin structures, as well as a novel calcium binding site situated between repeats I and IV. By means of comparison, the crystal structures of three different alpha-giardins known to date indicate that these proteins engage different calcium coordination schemes, among each other, as well as compared to annexins of groups A-D. Evaluation of the calcium-dependent binding to acidic phosphoplipid membranes revealed that this process is not only mediated but also regulated by the environmental calcium concentration. Uniquely within the large family of annexins, α1-giardin disengages from the phospholipid membrane at high calcium concentrations possibly due to formation of a dimeric species. The observed behaviour is in line with changing calcium levels experienced by the parasite during excystation and may thus provide first insights into the molecular mechanisms underpinning the transformation and survival of the parasite in the host. PMID:22796298

  10. Ultra-high field NMR studies of antibody binding and site-specific phosphorylation of {alpha}-synuclein

    SciTech Connect

    Sasakawa, Hiroaki |; Sakata, Eri; Yamaguchi, Yoshiki; Masuda, Masami |; Mori, Tetsuya; Kurimoto, Eiji; Iguchi, Takeshi; Hisanaga, Shin-ichi; Iwatsubo, Takeshi; Hasegawa, Masato; Kato, Koichi |

    2007-11-23

    Although biological importance of intrinsically disordered proteins is becoming recognized, NMR analyses of this class of proteins remain as tasks with more challenge because of poor chemical shift dispersion. It is expected that ultra-high field NMR spectroscopy offers improved resolution to cope with this difficulty. Here, we report an ultra-high field NMR study of {alpha}-synuclein, an intrinsically disordered protein identified as the major component of the Lewy bodies. Based on NMR spectral data collected at a 920 MHz proton frequency, we performed epitope mapping of an anti-{alpha}-synuclein monoclonal antibody, and furthermore, characterized conformational effects of phosphorylation at Ser129 of {alpha}-synuclein.

  11. High voltage stability performance of a gamma ray detection device

    SciTech Connect

    Abdullah, Nor Arymaswati; Lombigit, Lojius; Rahman, Nur Aira Abd

    2014-02-12

    An industrial grade digital radiation survey meter device is currently being developed at Malaysian Nuclear Agency. This device used a cylindrical type Geiger Mueller (GM) which acts as a detector. GM detector operates at relatively high direct current voltages depend on the type of GM tube. This thin/thick walled cylindrical type of GM tube operates at 450-650 volts range. Proper value and stability performance of high voltage are important parameters to ensure that this device give a reliable radiation dose measurement. This paper will present an assessment of the stability and performance of the high voltage supply for radiation detector. The assessment is performed using System Identification tools box in MATLAB and mathematical statistics.

  12. Method for enhancing stability of high explosives, for purposes of transport or storage, and the stabilized high explosives

    DOEpatents

    Nutt, Gerald L.

    1991-01-01

    The stability of porous solid high explosives, for purposes of transport or storage, is enhanced by reducing the sensitivity to shock initiation of a reaction that leads to detonation. The pores of the explosive down to a certain size are filled under pressure with a stable, low melt temperature material in liquid form, and the combined material is cooled so the pore filling material solidifies. The stability can be increased to progressively higher levels by filling smaller pores. The pore filling material can be removed, at least partially, by reheating above its melt temperature and drained off so that the explosive is once more suitable for detonation.

  13. High Speed Flexible Optical Disk with Cylindrically Concaved Stabilizer

    NASA Astrophysics Data System (ADS)

    Aman, Yasutomo; Onagi, Nobuaki; Murata, Shozo; Sugimoto, Yasunori; Koide, Daiichi; Tokumaru, Haruki

    2007-06-01

    We developed a brand-new stabilizer with a cylindrically concaved active surface for a flexible optical disk system. The unique design enabled extremely stable driving of the flexible disk at rotational speeds over 10,000 rpm. We actually demonstrated the driving at rotational speeds of up to 15,000 rpm, the spindle motor limit of our optical disk tester. This highest rotational speed promises a maximum data transfer rate of more than 600 Mbps for the recording density of a Blu-ray Disc. This stable state was achieved using a simple control that just adjusts the relative axial position of the stabilizer against the flexible disk. Once the adjustment was made, high stability was maintained over a wide rotational speed, ranging from 4,000 to 15,000 rpm. In this stable state, the axial runout on the pickup scanning line was suppressed to less than 10 μm at all rotational speeds. By achieving this high performance with simplified stabilizer control, we have come close to putting our system into practical use.

  14. Phase stability in processing of high temperature intermetallic alloys

    SciTech Connect

    Perepezko, J.H.; Nunes, C.A.; Yi, S.H.; Thoma, D.J.

    1997-12-31

    In the development of high temperature intermetallics involving various aluminides, silicides and Laves phases, it has become evident that it is essential to consider the strong influence of materials processing throughout all stages. The underlying basis for alloy synthesis, processing and the assessment of thermal stability is established by the relevant phase equilibria, the characteristic diffusivities and the possible solidification reaction pathways. In almost all cases the microstructures of the most useful metallic alloys are multiphase assemblies in which the relative phase fractions, compositions and morphologies play key roles in optimizing the performance under high temperature conditions. The microstructure designs are usually tailored for strength, toughness, creep resistance and environmental stability and involve a balance of features derived from mixtures of a ductile phase and intermetallic phases. There is a clear experience that the level of materials processing can only be as sophisticated as the level of knowledge of the phase equilibria and the underlying kinetics. In many of the contemporary intermetallic alloys the phase stability must be considered in terms of multicomponent equilibria and non-stoichiometric intermetallic compositions. Recent developments in several important intermetallic alloy classes illustrate the guidance into alloy design and processing options provided by systematic studies of phase stability. 58 refs., 7 figs.

  15. Nanomicelle with long-term circulation and enhanced stability of camptothecin based on mPEGylated alpha,beta-poly (L-aspartic acid)-camptothecin conjugate.

    PubMed

    Zhang, Weilu; Huang, Jin; Fan, Naiqian; Yu, Jiahui; Liu, Yongbiao; Liu, Shiyuan; Wang, Daxin; Li, Yaping

    2010-11-01

    To enhance the stability and long-term circulation of camptothecin (CPT), mPEGylated alpha,beta-poly (L-aspartic acid)-CPT conjugates were synthesized, and used to fabricate nanomicelle. Firstly, alpha,beta-poly (L-aspartic acid) derivative (PAA-der) containing alkyne groups was synthesized via the ring-opening of PSI with propargyl amine. And then, azide-functionalized CPT derivatives (CPT-N(3)) and azide-terminated poly (ethylene glycol) methyl ether (mPEG-N(3)) were conjugated with PAA-der by click cycloaddition to give mPEG-graft-PAA-CPT conjugates. The formation of mPEG-graft-PAA-CPT nanomicelles was confirmed by fluorescence spectrophotoscopy and particle size measurements. It was found that all the nanomicelles showed spherical shapes with size about 178 nm. MPEG-graft-PAA-CPT nanomicelles showed good storage stability, even incubation at 37 degrees C for 60 days, and improved the stability of CPT lactone form in aqueous media. A steady release rate of CPT was kept for 72h, suggested the great potential of mPEG-graft-PAA-CPT nanomicelles as polymer prodrug of CPT. PMID:20674289

  16. Stability of LAPONITE®-stabilized high internal phase Pickering emulsions under shear.

    PubMed

    Dinkgreve, M; Velikov, K P; Bonn, D

    2016-08-17

    Colloidal particles are often used to make Pickering emulsions that are reported to be very stable. Commonly the stabilization is a combined effect of particle adsorbing at the fluid interface and a particle network in the continuous phase; the contribution of each to the overall stability is difficult to assess. We investigate the role of LAPONITE® particles on high internal phase emulsion stability by considering three different situations: emulsion stabilization by surfactant only, by surfactant plus clay particles, and finally clay particles only. To clarify the structure of the emulsion and the role of the clay particles, we have succeeded in fluorescently labelling the clay particles by adsorbing the dye onto the particle surfaces. This allows us to show directly using confocal microscopy, that the clay particles are not only located at the interface but also aggregate and form a gel in the continuous aqueous phase. We show that the emulsions in the presence of surfactant (with or without clay) are stable to coalescence and shear. Without surfactant (with only LAPONITE® as stabilizer) the emulsions are stable to coalescence for several weeks, however they destabilize rapidly under shear. Our results suggest that the formation of the emulsions is mostly due to gel formation of the clay particles in the continuous phase, rather than that the clay is an emulsifier. This gel formation also accounts for the instability of the emulsions to shear that we observe caused by shear thinning of the continuous gel and inability of the adsorbed particles to rearrange effectively around the droplets due to their attractive nature. PMID:27485394

  17. Structure-based analysis of high pressure adaptation of alpha-actin.

    PubMed

    Morita, Takami

    2003-07-25

    Deep-sea fishes occur to depths of several thousand meters, and at these abyssal depths encounter pressures that shallower living fishes cannot tolerate. Tolerance of abyssal pressures by deep-sea fish is likely to depend in part on adaptive modifications of proteins. However, the types of structural modifications to proteins that allow function at high pressure have not been discovered. To elucidate the mechanisms of protein adaptation to high pressure, we cloned the alpha-skeletal actin cDNAs from two abyssal Coryphaenoides species, C. armatus and C. yaquinae, and identified three amino acid substitutions, V54A or L67P, Q137K, and A155S, that distinguish these abyssal actins from orthologs of alpha-actin from non-abyssal Coryphaenoides. These substitutions, Q137K and A155S, prevent the dissociation reactions of ATP and Ca2+ from being influenced by high pressure. In particular, the lysine residue at position 137 results in a much smaller apparent volume change in the Ca2+ dissociation reaction. The V54A or L67P substitution reduces the volume change associated with actin polymerization and has a role in maintaining the DNase I activity of actin at high pressure. Together, these results indicate that a few amino acid substitutions in key functional positions can adaptively alter the pressure sensitivity of a protein. PMID:12740368

  18. X-rays structural analysis and thermal stability studies of the ternary compound {alpha}-AlFeSi

    SciTech Connect

    Roger, J.; Bosselet, F.; Viala, J.C.

    2011-05-15

    From literature data presently available, the decomposition temperature and the nature of the decomposition reaction of the ternary compound {alpha}-AlFeSi (also designated as {alpha}{sub H} or {tau}{sub 5}) are not clearly identified. Moreover, some uncertainties remain concerning its crystal structure. The crystallographic structure and thermochemical behaviour of the ternary compound {alpha}-AlFeSi were meticulously studied. The crystal structure of {alpha}-AlFeSi was examined at room temperature from X-ray single crystal intensity data. It presents hexagonal symmetry, space group P6{sub 3}/mmc with unit cell parameters (293 K) a=12.345(2) A and c=26.210(3) A (V=3459 A{sup 3}). The average chemical formula obtained from refinement is Al{sub 7.1}Fe{sub 2}Si. From isothermal reaction-diffusion experiments and Differential Thermal Analysis, the title compound decomposes peritectically upon heating into {theta}-Fe{sub 4}Al{sub 13}(Si), {gamma}-Al{sub 3}FeSi and a ternary Al-rich liquid. Under atmospheric pressure, the temperature of this reversible transformation has been determined to be 772{+-}12 {sup o}C. -- Graphical abstract: Partial representation of the crystal structure of the {alpha}-Al{sub 7.1}Fe{sub 2}Si compound. Display Omitted Highlights: The main findings of our work are: {yields} a detailed X-rays crystal structure determination of the ternary compound {alpha}-AlFeSi. {yields} The precision of the silicon atoms positions in the crystal structure. {yields} A precised determination of the decomposition temperature of this compound.

  19. High gain proportional rf control stability at TESLA cavities

    NASA Astrophysics Data System (ADS)

    Vogel, Elmar

    2007-05-01

    Fast proportional rf control is used as the basis for rf field regulation in actual linear accelerator projects like the international linear collider (ILC) and the European x-ray free electron laser (XFEL) based on TESLA technology. Additional control loops improve the field regulation by treating repetitive effects and compensating the beam loading. Nevertheless, the ability for high gain operation of the fast loops is desirable for the strong suppression of nonpredictive and nonrepetitive disturbances. TESLA cavities host nine fundamental modes (FMs) where only one is used for beam acceleration. The unwanted FMs have a significant influence on the proportional rf control loop stability at high gains. Within this paper, the stability of proportional rf control loops taking the FMs and digitalization effects into account will be discussed in detail together with measures enabling a significant increase of the gain values.

  20. A high stability and repeatability electrochemical scanning tunneling microscope

    SciTech Connect

    Xia, Zhigang; Wang, Jihao; Lu, Qingyou; Hou, Yubin

    2014-12-15

    We present a home built electrochemical scanning tunneling microscope (ECSTM) with very high stability and repeatability. Its coarse approach is driven by a closely stacked piezo motor of GeckoDrive type with four rigid clamping points, which enhances the rigidity, compactness, and stability greatly. It can give high clarity atomic resolution images without sound and vibration isolations. Its drifting rates in XY and Z directions in solution are as low as 84 pm/min and 59 pm/min, respectively. In addition, repeatable coarse approaches in solution within 2 mm travel distance show a lateral deviation less than 50 nm. The gas environment can be well controlled to lower the evaporation rate of the cell, thus reducing the contamination and elongating the measurement time. Atomically resolved SO{sub 4}{sup 2−} image on Au (111) work electrode is demonstrated to show the performance of the ECSTM.

  1. Electronics design for a high precision image stabilization system

    NASA Astrophysics Data System (ADS)

    Casas, A.; Roma, D.; Carmona, M.; Gómez, J. M.; Bosch, J.; López, M.; Sabater, J.; Herms, A.; Maue, T.; Nakai, E.; Volkmer, R.; Schmidt, W.

    2014-07-01

    A very high precision Image Stabilization System has been designed for the Solar Orbiter mission. The different components that have been designed are the Correlation Tracking Camera (CTC), Tip-Tilt controller (TTC) and the system control in order to achieve the specified requirements. For the CTC, in order to achieve the required resolution of 12 bits and reduced power consumption, we used an external ADC. For the TTC, a special focus has been dedicated to a 55 V linear regulator in a QUASI-LDO configuration and a Tip-Tilt driver in a transconductance amplifier architecture. Results show that the full system reaches an attenuation of 1/10th of a pixel at 10Hz. The TTC provides a high voltage span, enough slew-rate and the needed stability levels.

  2. Measurement of dosimetric parameters for the Alpha-Omega high-dose-rate Iridium-192 source

    SciTech Connect

    Muller-Runkel, R. . E-mail: renate.muller@ssfhs.org

    2005-09-30

    Thermoluminescent (TLD) measurements of dose-rate constant, anisotropy function, and radial dose function are reported for the Alpha-Omega high dose rate (HDR) Iridium-192 ({sup 192}Ir) source, which has been available since 1998 for use in the MicroSelectron HDR afterloader manufactured by the Nucletron Corporation. Measurement results are compared with published or available Monte Carlo calculations for both sources. They are found in good agreement, and, within experimental accuracy, no difference is seen in the dosimetric parameters of both sources.

  3. Destabilization of the shear Alfven mode by alpha particles and other high energy ions

    NASA Astrophysics Data System (ADS)

    Belikov, V. S.; Kolesnichenko, Ya. I.; Silivra, O. A.

    1992-08-01

    Toroidal Alfven eigenmode (TAE) and elliptical Alfven eigenmode (EAE) instabilities in plasmas with high energy ions are considered in the context of local theory. The instability growth rate is found for cases when waves are excited by alpha particles or by ions produced as a result of neutral injection or RF heating. Electron and ion Landau damping due to the toroidal sideband wave-particle interaction is also calculated. The electron damping rate is shown to be much lower than the generally accepted value. The TAE instability observed in the experiment with neutral beam injection on TFTR is analysed and the principal experimental features of TAE instability are explained

  4. Alpha channeling with high-field launch of lower hybrid waves

    SciTech Connect

    Ochs, I. E.; Bertelli, N.; Fisch, N. J.

    2015-11-04

    Although lower hybrid waves are effective at driving currents in present-day tokamaks, they are expected to interact strongly with high-energy particles in extrapolating to reactors. In the presence of a radial alpha particle birth gradient, this interaction can take the form of wave amplification rather than damping. While it is known that this amplification more easily occurs when launching from the tokamak high-field side, the extent of this amplification has not been made quantitative. Here, by tracing rays launched from the high- field-side of a tokamak, the required radial gradients to achieve amplification are calculated for a temperature and density regime consistent with a hot-ion-mode fusion reactor. As a result, these simulations, while valid only in the linear regime of wave amplification, nonetheless illustrate the possibilities for wave amplification using high-field launch of the lower hybrid wave.

  5. Alpha channeling with high-field launch of lower hybrid waves

    DOE PAGESBeta

    Ochs, I. E.; Bertelli, N.; Fisch, N. J.

    2015-11-04

    Although lower hybrid waves are effective at driving currents in present-day tokamaks, they are expected to interact strongly with high-energy particles in extrapolating to reactors. In the presence of a radial alpha particle birth gradient, this interaction can take the form of wave amplification rather than damping. While it is known that this amplification more easily occurs when launching from the tokamak high-field side, the extent of this amplification has not been made quantitative. Here, by tracing rays launched from the high- field-side of a tokamak, the required radial gradients to achieve amplification are calculated for a temperature and densitymore » regime consistent with a hot-ion-mode fusion reactor. As a result, these simulations, while valid only in the linear regime of wave amplification, nonetheless illustrate the possibilities for wave amplification using high-field launch of the lower hybrid wave.« less

  6. Alpha channeling with high-field launch of lower hybrid waves

    SciTech Connect

    Ochs, I. E.; Bertelli, N.; Fisch, N. J.

    2015-11-15

    Although lower hybrid waves are effective at driving currents in present-day tokamaks, they are expected to interact strongly with high-energy particles in extrapolating to reactors. In the presence of a radial alpha particle birth gradient, this interaction can take the form of wave amplification rather than damping. While it is known that this amplification more easily occurs when launching from the tokamak high-field side, the extent of this amplification has not been made quantitative. Here, by tracing rays launched from the high-field-side of a tokamak, the required radial gradients to achieve amplification are calculated for a temperature and density regime consistent with a hot-ion-mode fusion reactor. These simulations, while valid only in the linear regime of wave amplification, nonetheless illustrate the possibilities for wave amplification using high-field launch of the lower hybrid wave.

  7. Influence of Si and W additions on high temperature oxidation of {gamma}-{alpha}{sub 2} Ti-Al alloys

    SciTech Connect

    Tomasi, A.; Noseda, C.; Nazmy, M.; Gialanella, S.

    1997-12-31

    Titanium aluminides have potential interest for high temperature applications because of their low density and high temperature strength. In this study the isothermal oxidation behavior in air and in the temperature range 700--850 C of {gamma}-{alpha}{sub 2}Ti-Al bulk alloys with different additions of W (0--9.5 wt.%) and Si (0--5.0 wt.%) was investigated. The samples were prepared by arc-melting starting from pure element powders (99.99%). After thermal treatments, for homogenization and phase stabilization, the samples were tested using a thermal analysis apparatus in order to evaluate their oxidation resistance. The oxidation rates show the beneficial effect of the W and Si additions. The growth and adherence to the protective scale on alloys have been investigated in conjunction with detailed oxide scale characterization using the techniques of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results of the study are used for critical assessment of the oxidation mechanisms leading to the formation of surface layers of different compositions.

  8. Organic underlayer materials with exceptionally high thermal stability

    NASA Astrophysics Data System (ADS)

    Cheon, Hwan-Sung; Yoon, Kyong-Ho; Kim, Min-Soo; Oh, Sung Bae; Song, Jee-Yun; Tokareva, Nataliya; Kim, Jong-Seob; Chang, Tuwon

    2009-03-01

    Multilayer hardmask (MLHM) schemes have been implemented as an indispensable process for ArF lithography which continues to demand thinner photoresist films. There are many variations of MLHM and semiconductor manufacturers choose to adopt their own designs, depending on their specific needs and technical advances. The quad-layer stack consisting of photoresist, organic ARC, CVD Si hardmask, and spin-on carbon underlayer is one of them. Despite the need for wafer transporting between the spin track and CVD equipment, this scheme is attractive because it can avoid laborious elaboration of sophisticated etching chemistries for spin-on Si-ARC and carbon underlayer. One of the issues arising from the mixed film forming process is the thermal stability of carbon underlayer at high temperatures during the CVD process of the Si hardmask. Organic underlayer which shows high thermal stability is crucial for this mixed hardmask process. These types of thermally stable organic film can also be used for other applications such as the spacer patterning technique for pitch size shrinkage. In this paper, we discuss the development of organic resins with high thermal stability, their physical properties, and their lithographic behaviors in the MLHM schemes.

  9. Experience with Ada on the F-18 High Alpha Research Vehicle Flight Test Program

    NASA Technical Reports Server (NTRS)

    Regenie, Victoria A.; Earls, Michael; Le, Jeanette; Thomson, Michael

    1992-01-01

    Considerable experience was acquired with Ada at the NASA Dryden Flight Research Facility during the on-going High Alpha Technology Program. In this program, an F-18 aircraft was highly modified by the addition of thrust-vectoring vanes to the airframe. In addition, substantial alteration was made in the original quadruplex flight control system. The result is the High Alpha Research Vehicle. An additional research flight control computer was incorporated in each of the four channels. Software for the research flight control computer was written in Ada. To date, six releases of this software have been flown. This paper provides a detailed description of the modifications to the research flight control system. Efficient ground-testing of the software was accomplished by using simulations that used the Ada for portions of their software. These simulations are also described. Modifying and transferring the Ada for flight software to the software simulation configuration has allowed evaluation of this language. This paper also discusses such significant issues in using Ada as portability, modifiability, and testability as well as documentation requirements.

  10. Experience with Ada on the F-18 High Alpha Research Vehicle flight test program

    NASA Technical Reports Server (NTRS)

    Regenie, Victoria A.; Earls, Michael; Le, Jeanette; Thomson, Michael

    1994-01-01

    Considerable experience has been acquired with Ada at the NASA Dryden Flight Research Facility during the on-going High Alpha Technology Program. In this program, an F-18 aircraft has been highly modified by the addition of thrust-vectoring vanes to the airframe. In addition, substantial alteration was made in the original quadruplex flight control system. The result is the High Alpha Research Vehicle. An additional research flight control computer was incorporated in each of the four channels. Software for the research flight control computer was written Ada. To date, six releases of this software have been flown. This paper provides a detailed description of the modifications to the research flight control system. Efficient ground-testing of the software was accomplished by using simulations that used the Ada for portions of their software. These simulations are also described. Modifying and transferring the Ada flight software to the software simulation configuration has allowed evaluation of this language. This paper also discusses such significant issues in using Ada as portability, modifiability, and testability as well as documentation requirements.

  11. Nonlinear stability and control study of highly maneuverable high performance aircraft, phase 2

    NASA Technical Reports Server (NTRS)

    Mohler, R. R.

    1992-01-01

    Research leading to the development of new nonlinear methodologies for the adaptive control and stability analysis of high angle of attack aircraft such as the F-18 is discussed. The emphasis has been on nonlinear adaptive control, but associated model development, system identification, stability analysis, and simulation were studied in some detail as well. Studies indicated that nonlinear adaptive control can outperform linear adaptive control for rapid maneuvers with large changes in angle of attack. Included here are studies on nonlinear model algorithmic controller design and an analysis of nonlinear system stability using robust stability analysis for linear systems.

  12. FIRST SPECTROSCOPIC EVIDENCE FOR HIGH IONIZATION STATE AND LOW OXYGEN ABUNDANCE IN Ly{alpha} EMITTERS ,

    SciTech Connect

    Nakajima, Kimihiko; Shimasaku, Kazuhiro; Hashimoto, Takuya; Ono, Yoshiaki; Ouchi, Masami; Lee, Janice C.

    2013-05-20

    We present results from Keck/NIRSPEC and Magellan/MMIRS follow-up spectroscopy of Ly{alpha} emitters (LAEs) at z = 2.2 identified in our Subaru narrowband survey. We successfully detect H{alpha} emission from seven LAEs, and perform a detailed analysis of six LAEs free from active galactic nucleus activity, two out of which, CDFS-3865 and COSMOS-30679, have [O II] and [O III] line detections. They are the first [O II]-detected LAEs at high-z, and their [O III]/[O II] ratios and R23-indices provide the first simultaneous determinations of ionization parameter and oxygen abundance for LAEs. CDFS-3865 has a very high ionization parameter (q{sub ion}=2.5{sup +1.7}{sub -0.8} Multiplication-Sign 10{sup 8} cm s{sup -1}) and a low oxygen abundance (12+ log (O/H)=7.84{sup +0.24}{sub -0.25}) in contrast with moderate values of other high-z galaxies such as Lyman break galaxies (LBGs). COSMOS-30679 also possesses a relatively high ionization parameter (q{sub ion}=8{sup +10}{sub -4} Multiplication-Sign 10{sup 7} cm s{sup -1}) and a low oxygen abundance (12+ log (O/H)=8.18{sup +0.28}{sub -0.28}). Both LAEs appear to fall below the mass-metallicity relation of z {approx} 2 LBGs. Similarly, a low metallicity of 12 + log (O/H) < 8.4 is independently indicated for typical LAEs from a composite spectrum and the [N II]/H{alpha} index. Such high ionization parameters and low oxygen abundances can be found in local star-forming galaxies, but this extreme local population occupies only {approx}0.06% of the Sloan Digital Sky Survey spectroscopic galaxy sample with a number density {approx}100 times smaller than that of LAEs. With their high ionization parameters and low oxygen abundances, LAEs would represent an early stage of galaxy formation dominated by massive stars in compact star-forming regions. High-q{sub ion} galaxies like LAEs would produce ionizing photons efficiently with a high escape fraction achieved by density-bounded H II regions, which would significantly contribute to

  13. Novel active stabilization technology in highly crosslinked UHMWPEs for superior stability

    NASA Astrophysics Data System (ADS)

    Oral, Ebru; Neils, Andrew L.; Wannomae, Keith K.; Muratoglu, Orhun K.

    2014-12-01

    Radiation cross-linked ultrahigh molecular weight polyethylene (UHMWPE) is the bearing of choice in joint arthroplasty. The demands on the longevity of this polymer are likely to increase with the recently advancing deterioration of the performance of alternative metal-on-metal implants. Vitamin E-stabilized, cross-linked UHMWPEs are considered the next generation of improved UHMWPE bearing surfaces for improving the oxidation resistance of the polymer. It was recently discovered that in the absence of radiation-induced free radicals, lipids absorbed into UHMWPE from the synovial fluid can initiate oxidation and result in new free radical-mediated oxidation mechanisms. In the presence of radiation-induced free radicals, it is possible for the polymer to oxidize through both existing free radicals at the time of implantation and through newly formed free radicals in vivo. Thus, we showed that reducing the radiation-induced free radicals in vitamin E-stabilized UHMWPE would increase its oxidative stability and presumably lead to improved longevity. We describe mechanical annealing and warm irradiation of irradiated vitamin E blends as novel methods to eliminate 99% of radiation-induced free radicals without sacrificing crystallinity. These are significant improvements in the processing of highly cross-linked UHMWPE for joint implants with improved longevity.

  14. High-resolution optical frequency metrology with stabilized femtosecond lasers

    NASA Astrophysics Data System (ADS)

    Jones, Ronald Jason

    The merging of such seemingly disparate fields as optical frequency metrology and ultrafast physics over the past few years has had a revolutionary impact on both fields. Extensive research over the past several decades has focused on stabilizing cw lasers to atomic and molecular transitions. These transitions in the optical and near-infrared regimes provide some of the highest Q's accessible in spectroscopy due to their high resonant frequencies (Q ≡ nu o/deltanu). Modern experiments have enjoyed increasing levels of precision and accuracy due to such stabilized laser systems. A long standing problem in optical frequency metrology, however, is the difficulty to perform direct frequency measurements in the optical spectrum. Traditional optical frequency chains are complex, costly, and lack flexibility. Recent experiments based on mode-locked femtosecond (fs) lasers promise to eliminate this problem and make optical frequency measurements accessible as a general laboratory tool. The use of fs lasers now enables the direct measurement of optical transitions by simply linking these frequencies to the repetition rate of the fs laser. The ability of the femtosecond laser to link the optical and radio frequency regimes is ultimately limited by its stability. In this dissertation, we present a novel stabilization scheme in which the frequency, phase, and repetition rate of a Kerr-lens mode-locked (KLM) ti:sapphire laser are locked to that of an ultra-stable Fabry-Perot reference cavity. The large signal to noise ratio of the recovered cavity resonance allows the superb short term stability (tau < 1 second) of the passive reference cavity to be transferred to the femtosecond laser. This technique may find future application in any experiment involving the use of femtosecond pulses in which a resonant cavity is employed, such as intracavity studies of light-matter interactions with ultra-short pulses. The short term instability of the cavity stabilized femtosecond laser

  15. Process Design Concepts for Stabilization of High Level Waste Calcine

    SciTech Connect

    T. R. Thomas; A. K. Herbst

    2005-06-01

    The current baseline assumption is that packaging ¡§as is¡¨ and direct disposal of high level waste (HLW) calcine in a Monitored Geologic Repository will be allowed. The fall back position is to develop a stabilized waste form for the HLW calcine, that will meet repository waste acceptance criteria currently in place, in case regulatory initiatives are unsuccessful. A decision between direct disposal or a stabilization alternative is anticipated by June 2006. The purposes of this Engineering Design File (EDF) are to provide a pre-conceptual design on three low temperature processes under development for stabilization of high level waste calcine (i.e., the grout, hydroceramic grout, and iron phosphate ceramic processes) and to support a down selection among the three candidates. The key assumptions for the pre-conceptual design assessment are that a) a waste treatment plant would operate over eight years for 200 days a year, b) a design processing rate of 3.67 m3/day or 4670 kg/day of HLW calcine would be needed, and c) the performance of waste form would remove the HLW calcine from the hazardous waste category, and d) the waste form loadings would range from about 21-25 wt% calcine. The conclusions of this EDF study are that: (a) To date, the grout formulation appears to be the best candidate stabilizer among the three being tested for HLW calcine and appears to be the easiest to mix, pour, and cure. (b) Only minor differences would exist between the process steps of the grout and hydroceramic grout stabilization processes. If temperature control of the mixer at about 80„aC is required, it would add a major level of complexity to the iron phosphate stabilization process. (c) It is too early in the development program to determine which stabilizer will produce the minimum amount of stabilized waste form for the entire HLW inventory, but the volume is assumed to be within the range of 12,250 to 14,470 m3. (d) The stacked vessel height of the hot process vessels

  16. Comprehensive evaluation of the linear stability of Alfvén eigenmodes driven by alpha particles in an ITER baseline scenario

    NASA Astrophysics Data System (ADS)

    Figueiredo, A. C. A.; Rodrigues, P.; Borba, D.; Coelho, R.; Fazendeiro, L.; Ferreira, J.; Loureiro, N. F.; Nabais, F.; Pinches, S. D.; Polevoi, A. R.; Sharapov, S. E.

    2016-07-01

    The linear stability of Alfvén eigenmodes in the presence of fusion-born alpha particles is thoroughly assessed for two variants of an ITER baseline scenario, which differ significantly in their core and pedestal temperatures. A systematic approach based on CASTOR-K (Borba and Kerner 1999 J. Comput. Phys. 153 101; Nabais et al 2015 Plasma Sci. Technol. 17 89) is used that considers all possible eigenmodes for a given magnetic equilibrium and determines their growth rates due to alpha-particle drive and Landau damping on fuel ions, helium ashes and electrons. It is found that the fastest growing instabilities in the aforementioned ITER scenario are core-localized, low-shear toroidal Alfvén eigenmodes. The largest growth-rates occur in the scenario variant with higher core temperatures, which has the highest alpha-particle density and density gradient, for eigenmodes with toroidal mode numbers n≈ 30 . Although these eigenmodes suffer significant radiative damping, which is also evaluated, their growth rates remain larger than those of the most unstable eigenmodes found in the variant of the ITER baseline scenario with lower core temperatures, which have n≈ 15 and are not affected by radiative damping.

  17. Stability of high. beta. large aspect ratio tokamaks

    SciTech Connect

    Cowley, S.C.

    1991-10-01

    High {beta}({beta}{much gt} {epsilon}/q{sup 2}) large aspect ratio ({epsilon} {much gt} 1) tokamak equilibria are shown to be always stable to ideal M.H.D. modes that are localized about a flux surface. Both the ballooning and interchange modes are shown to be stable. This work uses the analytic high {beta} large aspect ratio tokamak equilibria developed by Cowley et.al., which are valid for arbitrary pressure and safety factor profiles. The stability results make no assumption about these profiles or the shape of the boundary. 14 refs., 4 figs.

  18. How to produce high specific activity tin-117m using alpha particle beam.

    PubMed

    Duchemin, C; Essayan, M; Guertin, A; Haddad, F; Michel, N; Métivier, V

    2016-09-01

    Tin-117m is an interesting radionuclide for both diagnosis and therapy, thanks to the gamma-ray and electron emissions, respectively, resulting from its decay to tin-117g. The high specific activity of tin-117m is required in many medical applications, and it can be obtained using a high energy alpha particle beam and a cadmium target. The experiments performed at the ARRONAX cyclotron (Nantes, France) using an alpha particle beam delivered at 67.4MeV provide a measurement of the excitation function of the Cd-nat(α,x)Sn-117m reaction and the produced contaminants. The Cd-116(α,3n)Sn-117m production cross section has been deduced from these experimental results using natural cadmium. Both production yield and specific activity as a function of the projectile energy have been calculated. These informations help to optimize the irradiation conditions to produce tin-117m with the required specific activity using α particles with a cadmium target. PMID:27344526

  19. Enhanced trigger for the NIFFTE fissionTPC in presence of high-rate alpha backgrounds

    NASA Astrophysics Data System (ADS)

    Bundgaard, Jeremy; Niffte Collaboration

    2015-10-01

    Nuclear physics and nuclear energy communities call for new, high precision measurements to improve existing fission models and design next generation reactors. The Neutron Induced Fission Fragment Tracking experiment (NIFFTE) has developed the fission Time Projection Chamber (fissionTPC) to measure neutron induced fission with unrivaled precision. The fissionTPC is annually deployed to the Weapons Neutron Research facility at Los Alamos Neutron Science Center where it operates with a neutron beam passing axially through the drift volume, irradiating heavy actinide targets to induce fission. The fissionTPC was developed at the Lawrence Livermore National Laboratory's TPC lab, where it measures spontaneous fission from radioactive sources to characterize detector response, improve performance, and evolve the design. To measure 244Cm, we've developed a fission trigger to reduce the data rate from alpha tracks while maintaining a high fission detection efficiency. In beam, alphas from 239Pu are a large background when detecting fission fragments; implementing the fission trigger will greatly reduce this background. The implementation of the cathode fission trigger in the fissionTPC will be presented along with a detailed study of its efficiency.

  20. Solutions for stability and astigmatism in high power laser resonators

    NASA Astrophysics Data System (ADS)

    Narro, R.; Arronte, M.; de Posada, E.; Ponce, L.; Rodríguez, E.

    2009-09-01

    A method is proposed for the design of fundamental mode high power resonators, with joined stability zones. A parameter is created which gives the minimum length a laser resonator should have while having at the same time the broadest stabilities zones. For multimode and large mode volume resonators, a configuration is introduced for maximizing the laser overall efficiency due to the compensation of the astigmatism induced by the flash lamp pumping heating. The later configuration proposes a dual-active medium resonator, with 90 degree rotation around the optical axis between the astigmatic thermal lenses of the mediums. The reliability of this configuration is corroborated experimentally using a Nd:YAG dual-active medium resonator. It is found that in the pumping power range where the astigmatism compensation is possible, the overall efficiency is constant, even when increasing the excitation power with the consequent increase of the thermal lens dioptric power.

  1. Cementitious Stabilization of Mixed Wastes with High Salt Loadings

    SciTech Connect

    Spence, R.D.; Burgess, M.W.; Fedorov, V.V.; Downing, D.J.

    1999-04-01

    Salt loadings approaching 50 wt % were tolerated in cementitious waste forms that still met leach and strength criteria, addressing a Technology Deficiency of low salt loadings previously identified by the Mixed Waste Focus Area. A statistical design quantified the effect of different stabilizing ingredients and salt loading on performance at lower loadings, allowing selection of the more effective ingredients for studying the higher salt loadings. In general, the final waste form needed to consist of 25 wt % of the dry stabilizing ingredients to meet the criteria used and 25 wt % water to form a workable paste, leaving 50 wt % for waste solids. The salt loading depends on the salt content of the waste solids but could be as high as 50 wt % if all the waste solids are salt.

  2. Ion Desorption Stability in Superconducting High Energy Physics Proton Colliders

    SciTech Connect

    Turner, W.C.

    1995-05-29

    of the diagonal uncoupled feedback loops are first order in the ion desorption coefficients whereas the gains of the off diagonal coupled feedback loops are second and higher order. For this reason it turns out that in practical cases stability is dominated by the uncoupled diagonal elements and the inverse of the largest first order closed loop gain is a useful estimate of the margin of stability. In contrast to the case of a simple cold beam tube, the stability condition for a beam screen does not contain the desorption coefficient for physisorbed molecules, even when the screen temperature is low enough that there is a finite surface density of them on the screen surface. Consequently there does not appear to be any particular advantage to operating the beam screen at high enough temperature to avoid physisorption. Numerical estimates of ion desorption stability are given for a number of cases relevant to LHC and all of the ones likely to be encountered were found to be stable. The most important case, a I % transparency beam screen at {approx}4.2 K, was found to have a stability safety margin of approximately thirty determined by ion desorption of CO. Ion desorption of H{sub 2} is about a factor of eighty less stringent than CO. For these estimates the beam tube surface was assumed to be solvent cleaned but otherwise untreated, for example by a very high temperature vacuum bakeout or by glow discharge cleaning.

  3. Detection of reactive oxygen species via endogenous oxidative pentose phosphate cycle activity in response to oxygen concentration: implications for the mechanism of HIF-1alpha stabilization under moderate hypoxia.

    PubMed

    Tuttle, Stephen W; Maity, Amit; Oprysko, Patricia R; Kachur, Alexander V; Ayene, Iraimoudi S; Biaglow, John E; Koch, Cameron J

    2007-12-21

    The oxidative pentose phosphate cycle (OPPC) is necessary to maintain cellular reducing capacity during periods of increased oxidative stress. Metabolic flux through the OPPC increases stoichiometrically in response to a broad range of chemical oxidants, including those that generate reactive oxygen species (ROS). Here we show that OPPC sensitivity is sufficient to detect low levels of ROS produced metabolically as a function of the percentage of O2. We observe a significant decrease in OPPC activity in cells incubated under severe and moderate hypoxia (ranging from <0.01 to 4% O2), whereas hyperoxia (95% O2) results in a significant increase in OPPC activity. These data indicate that metabolic ROS production is directly dependent on oxygen concentration. Moreover, we have found no evidence to suggest that ROS, produced by mitochondria, are needed to stabilize hypoxia-inducible factor 1alpha (HIF-1alpha) under moderate hypoxia. Myxothiazol, an inhibitor of mitochondrial electron transfer, did not prevent HIF-1alpha stabilization under moderate hypoxia. Moreover, the levels of HIF-1alpha that we observed after exposure to moderate hypoxia were comparable between rho0 cells, which lack functional mitochondria, and the wild-type cells. Finally, we find no evidence for stabilization of HIF-1alpha in response to the non-toxic levels of H2O2 generated by the enzyme glucose oxidase. Therefore, we conclude that the oxygen dependence of the prolyl hydroxylase reaction is sufficient to mediate HIF-1alpha stability under moderate as well as severe hypoxia. PMID:17666400

  4. ALPHN: A computer program for calculating ([alpha], n) neutron production in canisters of high-level waste

    SciTech Connect

    Salmon, R.; Hermann, O.W.

    1992-10-01

    The rate of neutron production from ([alpha], n) reactions in canisters of immobilized high-level waste containing borosilicate glass or glass-ceramic compositions is significant and must be considered when estimating neutron shielding requirements. The personal computer program ALPHA calculates the ([alpha], n) neutron production rate of a canister of vitrified high-level waste. The user supplies the chemical composition of the glass or glass-ceramic and the curies of the alpha-emitting actinides present. The output of the program gives the ([alpha], n) neutron production of each actinide in neutrons per second and the total for the canister. The ([alpha], n) neutron production rates are source terms only; that is, they are production rates within the glass and do not take into account the shielding effect of the glass. For a given glass composition, the user can calculate up to eight cases simultaneously; these cases are based on the same glass composition but contain different quantities of actinides per canister. In a typical application, these cases might represent the same canister of vitrified high-level waste at eight different decay times. Run time for a typical problem containing 20 chemical species, 24 actinides, and 8 decay times was 35 s on an IBM AT personal computer. Results of an example based on an expected canister composition at the Defense Waste Processing Facility are shown.

  5. ALPHN: A computer program for calculating ({alpha}, n) neutron production in canisters of high-level waste

    SciTech Connect

    Salmon, R.; Hermann, O.W.

    1992-10-01

    The rate of neutron production from ({alpha}, n) reactions in canisters of immobilized high-level waste containing borosilicate glass or glass-ceramic compositions is significant and must be considered when estimating neutron shielding requirements. The personal computer program ALPHA calculates the ({alpha}, n) neutron production rate of a canister of vitrified high-level waste. The user supplies the chemical composition of the glass or glass-ceramic and the curies of the alpha-emitting actinides present. The output of the program gives the ({alpha}, n) neutron production of each actinide in neutrons per second and the total for the canister. The ({alpha}, n) neutron production rates are source terms only; that is, they are production rates within the glass and do not take into account the shielding effect of the glass. For a given glass composition, the user can calculate up to eight cases simultaneously; these cases are based on the same glass composition but contain different quantities of actinides per canister. In a typical application, these cases might represent the same canister of vitrified high-level waste at eight different decay times. Run time for a typical problem containing 20 chemical species, 24 actinides, and 8 decay times was 35 s on an IBM AT personal computer. Results of an example based on an expected canister composition at the Defense Waste Processing Facility are shown.

  6. Graphene oxide immobilized enzymes show high thermal and solvent stability

    NASA Astrophysics Data System (ADS)

    Hermanová, Soňa; Zarevúcká, Marie; Bouša, Daniel; Pumera, Martin; Sofer, Zdeněk

    2015-03-01

    The thermal and solvent tolerance of enzymes is highly important for their industrial use. We show here that the enzyme lipase from Rhizopus oryzae exhibits exceptionally high thermal stability and high solvent tolerance and even increased activity in acetone when immobilized onto a graphene oxide (GO) nanosupport prepared by Staudenmaier and Brodie methods. We studied various forms of immobilization of the enzyme: by physical adsorption, covalent attachment, and additional crosslinking. The activity recovery was shown to be dependent on the support type, enzyme loading and immobilization procedure. Covalently immobilized lipase showed significantly better resistance to heat inactivation (the activity recovery was 65% at 70 °C) in comparison with the soluble counterpart (the activity recovery was 65% at 40 °C). Physically adsorbed lipase achieved over 100% of the initial activity in a series of organic solvents. These findings, showing enhanced thermal stability and solvent tolerance of graphene oxide immobilized enzyme, will have a profound impact on practical industrial scale uses of enzymes for the conversion of lipids into fuels.The thermal and solvent tolerance of enzymes is highly important for their industrial use. We show here that the enzyme lipase from Rhizopus oryzae exhibits exceptionally high thermal stability and high solvent tolerance and even increased activity in acetone when immobilized onto a graphene oxide (GO) nanosupport prepared by Staudenmaier and Brodie methods. We studied various forms of immobilization of the enzyme: by physical adsorption, covalent attachment, and additional crosslinking. The activity recovery was shown to be dependent on the support type, enzyme loading and immobilization procedure. Covalently immobilized lipase showed significantly better resistance to heat inactivation (the activity recovery was 65% at 70 °C) in comparison with the soluble counterpart (the activity recovery was 65% at 40 °C). Physically adsorbed

  7. In-Flight Wing Pressure Distributions for the NASA F/A-18A High Alpha Research Vehicle

    NASA Technical Reports Server (NTRS)

    Davis, Mark C.; Saltzman, John A.

    2000-01-01

    Pressure distributions on the wings of the F/A-18A High Alpha Research Vehicle (HARV) were obtained using both flush-mounted pressure orifices and surface-mounted pressure tubing. During quasi-stabilized 1-g flight, data were gathered at ranges for angle of attack from 5 deg to 70 deg, for angle of sideslip from -12 deg to +12 deg, and for Mach from 0.23 to 0.64, at various engine settings, and with and without the leading edge extension fence installed. Angle of attack strongly influenced the wing pressure distribution, as demonstrated by a distinct flow separation pattern that occurred between the range from 15 deg to 30 deg. Influence by the leading edge extension fence was evident on the inboard wing pressure distribution, but little influence was seen on the outboard portion of the wing. Angle-of-sideslip influence on wing pressure distribution was strongest at low angle of attack. Influence of Mach number was observed in the regions of local supersonic flow, diminishing as angle of attack was increased. Engine throttle setting had little influence on the wing pressure distribution.

  8. Stabilized high-accuracy optical tracking system (SHOTS)

    NASA Astrophysics Data System (ADS)

    Ruffatto, Donald; Brown, H. Donald; Pohle, Richard H.; Reiley, Michael F.; Haddock, Delmar D.

    2001-08-01

    This paper describes an 0.75 meter aperture, Stabilized High-accuracy Optical Tracking System (SHOTS), two of which are being developed by Textron Systems Corporation, under contract to the Navy's Space and Naval Warfare Systems Center, San Diego (SPAWAR-SD). The SHOTS design is optimized to meet the requirements of the Navy's Theater Ballistic Missile Defense (TBMD) testing program being conducted at the Kauai Pacific Missile Range Facility (PMRF). The SHOTS utilizes a high-precision, GPS aided inertial navigation unit (INU) coupled with a 3-axis, rate gyro stabilized mount which allows precision pointing to be achieved on either land or sea-based platforms. The SHOTS mount control system architecture, acquisition, tracking and pointing (ATP) functionality and methodology which allows the system to meet the TBMD mission data collection requirements are discussed. High frame rate visible and MWIR sensors are incorporated into the system design to provide the capability of capturing short duration events, e.g., missile-target intercepts. These sensors along with the supporting high speed data acquisition, recording and control subsystems are described. Simulations of the SHOTS imaging performance in TBMD measurement scenarios are presented along with an example of the image improvement being achieved with post-processing image reconstruction algorithms.

  9. A parametric study of planform and aeroelastic effects on aerodynamic center, alpha- and q-stability derivatives

    NASA Technical Reports Server (NTRS)

    Roskam, J.; Lan, C.

    1973-01-01

    Summarized are the aerodynamic center, alpha and q- aeroelastic effects on fighter-type aircraft in the 18,700 N gross range. The results indicate that with proper tailoring of planform (fixed or variable sweep), stiffner and elastic axis location it is possible to minimize trim requirements between selected extreme conditions. The inertial effects were found to be small for this class of aircraft.

  10. Stabilization of {alpha}-SiAlONs using a rare-earth mixed oxide (RE{sub 2}O{sub 3}) as sintering additive

    SciTech Connect

    Santos, C.; Silva, O.M.M.; Silva, C.R.M.

    2005-07-12

    {alpha}-SiAlONs are commonly produced by liquid phase sintering of Si{sub 3}N{sub 4} with AlN and Y{sub 2}O{sub 3} as additives. The formation of the {alpha}-SiAlONs using a mixed oxide (RE{sub 2}O{sub 3}), containing yttria and rare-earth oxides, as an alternative additive was investigated. Dense {alpha}-SiAlONs were obtained by gas-pressure sintering, starting from {alpha}-Si{sub 3}N{sub 4} and AlN-Y{sub 2}O{sub 3} or AlN-RE{sub 2}O{sub 3} as additives. The mixed oxide powder RE{sub 2}O{sub 3} was characterized by means of high-resolution synchrotron X-ray diffraction and compared to Y{sub 2}O{sub 3}. The X-ray diffraction analysis of the mixed oxide shows a pattern indicating a true solid solution formation. The Rietveld refinement of the crystal structure of the sintered {alpha}-SiAlON using AlN-RE{sub 2}O{sub 3} as additive revealed a similar crystal structure to the {alpha}-SiAlON using AlN-RE{sub 2}O{sub 3} as additive. The comparison of the microstructures of the both {alpha}-SiAlONs produced using pure Y{sub 2}O{sub 3} or RE{sub 2}O{sub 3}, revealed similar grain sizes of about 4.5 {mu}m with aspect ratios of about 5. Both materials show also similar mechanical properties, with hardness of 18.5 GPa and fracture toughness of 5 MPa m{sup 1/2}. It could be, thus, demonstrated that pure Y{sub 2}O{sub 3} can be substituted by the rare-earth solid solution, RE{sub 2}O{sub 3}, in the formation of {alpha}-SiAlONs, presenting similar microstructural and mechanical properties.

  11. Optimisation study of alpha-cyclotron production of At-211/Po-211g for high-LET metabolic radiotherapy purposes.

    PubMed

    Groppi, F; Bonardi, M L; Birattari, C; Menapace, E; Abbas, K; Holzwarth, U; Alfarano, A; Morzenti, S; Zona, C; Alfassi, Z B

    2005-01-01

    The production of no-carrier-added (NCA) alpha-emitter (211)At/(211g)Po radionuclides for high-LET targeted radiotherapy and immunoradiotherapy, through the (209)Bi(alpha,2n) reaction, together with the required wet radiochemistry and radioanalytical quality controls carried out at LASA is described, through dedicated irradiation experiments at the MC-40 cyclotron of JRC-Ispra. The amount of both the gamma-emitter (210)At and its long half-lived alpha-emitting daughter (210)Po is optimised and minimised by appropriate choice of energy and energy loss of alpha particle beam. The measured excitation functions for production of the main radioisotopic impurity (210)At-->(210)Po are compared with theoretical predictions from model calculations performed at ENEA. PMID:16055338

  12. Alpha-1-Antitrypsin: A Novel Human High Temperature Requirement Protease A1 (HTRA1) Substrate in Human Placental Tissue

    PubMed Central

    Frochaux, Violette; Hildebrand, Diana; Talke, Anja; Linscheid, Michael W.; Schlüter, Hartmut

    2014-01-01

    The human serine protease high temperature requirement A1 (HTRA1) is highly expressed in the placental tissue, especially in the last trimester of gestation. This suggests that HTRA1 is involved in placental formation and function. With the aim of a better understanding of the role of HTRA1 in the placenta, candidate substrates were screened in a placenta protein extract using a gel-based mass spectrometric approach. Protease inhibitor alpha-1-antitrypsin, actin cytoplasmic 1, tropomyosin beta chain and ten further proteins were identified as candidate substrates of HTRA1. Among the identified candidate substrates, alpha-1-antitrypsin (A1AT) was considered to be of particular interest because of its important role as protease inhibitor. For investigation of alpha-1-antitrypsin as substrate of HTRA1 synthetic peptides covering parts of the sequence of alpha-1-antitrypsin were incubated with HTRA1. By mass spectrometry a specific cleavage site was identified after met-382 (AIPM382↓383SIPP) within the reactive centre loop of alpha-1-antitrypsin, resulting in a C-terminal peptide comprising 36 amino acids. Proteolytic removal of this peptide from alpha-1-antitrypsin results in a loss of its inhibitor function. Beside placental alpha-1-antitrypsin the circulating form in human plasma was also significantly degraded by HTRA1. Taken together, our data suggest a link between the candidate substrates alpha-1-antitrypsin and the function of HTRA1 in the placenta in the syncytiotrophoblast, the cell layer attending to maternal blood in the villous tree of the human placenta. Data deposition: Mass spectrometry (MS) data have been deposited to the ProteomeXchange with identifier PXD000473. PMID:25329061

  13. Thermal Stabilization in a High Vacuum Cryogenic Optical System

    NASA Astrophysics Data System (ADS)

    Wallace, Rosa; Cripe, Jonathan; Corbitt, Thomas

    2016-03-01

    The existing technology for gravitational wave detection is limited in part by quantum noise. In our tabletop experiments, we are attempting to lower the noise floor to the quantum limit through the use of a seismically isolated cryogenic high vacuum environment, with the intention of exploring different methods to reduce quantum noise. In the development phase of this environment, we have implemented a customized strategy of ultraviolet irradiation combined with cryogenically cooled radiation shielding to reduce the impact of water vapor and blackbody radiation on the thermal stability of the cryogenic micro-components. Supported by National Science Foundation REU Site #1262890 and CAREER Award #1150531.

  14. Identification of high-affinity anti-IL-1. alpha. autoantibodies in normal human serum as an interfering substance in a sensitive enzyme-linked immunosorbent assay for IL-1. alpha

    SciTech Connect

    Mae, N.; Liberato, D.J.; Chizzonite, R.; Satoh, H. )

    1991-04-01

    A highly reproducible, sensitive, and specific sandwich enzyme-linked immunosorbent assay (ELISA) for recombinant human IL-1 {alpha} (rhIL-1 alpha) has been developed. Results from this ELISA have demonstrated that the concentration of rhIL-1 {alpha} added to normal human serum (NHS) decreased by 16.3% after 3 h and 24.9% after 6 h at room temperature. Molecular exclusion column chromatography with Sephacryl S-300 HR revealed that 125I-labeled IL-1 {alpha} added to normal human serum rapidly formed higher molecular weight complexes without indication of proteolytic degradation. The observed reduction in immunoreactivity was correlated with this protein complex formation and accounted for the apparent instability of rhIL-1 {alpha} in NHS. Immunoblot analysis indicated that the molecular weight of the binding protein was 150-160K, and the IL-1 {alpha} binding activity was removed and recovered from NHS by Protein-G affinity chromatography; indicating that the binding protein was IL-1 {alpha}-specific IgG. The binding of 125I-labeled IL-1 {alpha} to the serum binding proteins could be inhibited by unlabeled IL-1 alpha (IC50 = 7.4 {times} 10(-11) M) but not by unlabeled IL-1 {beta}. Kinetic analysis with 125I-labeled IL-1 alpha revealed that the average binding affinity of these IL-1 {alpha}-specific IgGs was 4.7 {times} 10(10) M-1. These results suggest that these autoantibodies may interfere with the detection of IL-1 {alpha} in human serum by various assay systems and also could be a regulator of circulating IL-1 {alpha}.

  15. High viscosity to highly dispersed PtPd bimetallic nanocrystals for enhanced catalytic activity and stability.

    PubMed

    Ying, Jie; Hu, Zhi-Yi; Yang, Xiao-Yu; Wei, Hao; Xiao, Yu-Xuan; Janiak, Christoph; Mu, Shi-Chun; Tian, Ge; Pan, Mu; Van Tendeloo, Gustaaf; Su, Bao-Lian

    2016-07-01

    A facile high-viscosity-solvent method is presented to synthesize PtPd bimetallic nanocrystals highly dispersed in different mesostructures (2D and 3D structures), porosities (large and small pore sizes), and compositions (silica and carbon). Further, highly catalytic activity, stability and durability of the nanometals have been proven in different catalytic reactions. PMID:27222099

  16. Special Form Testing of Sealed Source Encapsulation for High-Alpha-Activity Actinide Materials

    SciTech Connect

    Martinez, Oscar A

    2016-01-01

    In the United States all transportation of radioactive material is regulated by the U.S. Department of Transportation (DOT). Beginning in 2008 a new type of sealed-source encapsulation package was developed and tested by Oak Ridge National Laboratory (ORNL). These packages contain high-alpha-activity actinides and are regulated and transported in accordance with the requirements for DOT Class 7 hazardous material. The DOT provides specific regulations pertaining to special form encapsulation designs. The special form designation indicates that the encapsulated radioactive contents have a very low probability of dispersion even when subjected to significant structural events. The special form designs have been shown to simplify the delivery, transport, acceptance, and receipt processes. It is intended for these sealed-source encapsulations to be shipped to various facilities making it very advantageous for them to be certified as special form. To this end, DOT Certificates of Competent Authority (CoCAs) have been sought for the design suitable for containing high-alpha-activity actinide materials. This design consists of the high-alpha-activity material encapsulated within a triangular zirconia canister, referred to as a ZipCan, tile that is then enclosed by a spherical shell. The spherical shell design, with ZipCan tile inside, was tested for compliance with the special form regulations found in 49 CFR 173.469. The spherical enclosure was subjected to 9-m impact, 1 m percussion, and 10-minute thermal tests at the Packaging Evaluation Facility located at the National Transportation Research Center in Knoxville, TN USA and operated by ORNL. Before and after each test, the test units were subjected to a helium leak check and a bubble test. The ZipCan tiles and core were also subjected to the tests required for ISO 2919:2012(E), including a Class IV impact test and heat test and subsequently subjected to helium leakage rate tests [49 CFR 173.469(a)(4)(i)]. The impact

  17. Oxidative stability of crude mid-oleic sunflower oils from seeds with high gamma and delta tocopherol levels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sunflower oil typically has a tocopherol profile that consists primarily of alpha-tocopherol - usually 95% of the total tocopherol content. Gamma-, delta-tocopherols are better antioxidants in vitro than alpha-tocopherol. Therefore, the oxidative stability of sunflower oil could possibly be enhanc...

  18. Novel prediction method of beer foam stability using protein Z, barley dimeric alpha-amylase inhibitor-1 (BDAI-1) and yeast thioredoxin.

    PubMed

    Iimure, Takashi; Takoi, Kiyoshi; Kaneko, Takafumi; Kihara, Makoto; Hayashi, Katsuhiro; Ito, Kazutoshi; Sato, Kazuhiro; Takeda, Kazuyoshi

    2008-09-24

    Foam stability is an important quality trait of beer. Our previous results of two-dimensional gel electrophoresis (2DE) analyses of beer proteins implied a relationship between barley dimeric alpha-amylase inhibitor-1 (BDAI-1) and beer foam stability as judged by the NIBEM-T analyzer. To develop a novel prediction method of beer foam stability under different conditions of barley cultivar and malt modification, multiple linear regression analysis was applied. The spot intensities of major beer proteins on 2DE gel were quantified and used as explanatory variables. The foam stabilities of 25 beer samples each brewed from malt with different malt modification in one of the three cultivars (cultivars A, B, and C) were explained by the spot intensities of BDAI-1 at the 5% significance level ( r = 0.421). Furthermore, two other major protein spots (b0 and b5) were observed on the 2DE gels of Japanese commercial beer samples with different foam stability. Then, multiple regression for foam stability was calculated using these three spot intensities as explanatory variables. As a result, 72.1% of the beer foam stability in 25 beer samples was explained by a novel multiple regression equation calculated using spot b0 and BDAI-1 as positive explanatory variables and spot b5 as a negative variable. To verify the validity of the multiple regression equation and the explanatory variables, the beer foam stability in practical beer samples was analyzed. As a result, 81.5% of the beer foam stability in 10 Japanese commercial beer samples was also explained by using spot b0 and BDAI-1 as positive explanatory variables and spot b5 as a negative variable. Mass spectrometry analyses followed by database searches revealed that protein spots b0 and b5 were identified as protein Z originated from barley and thioredoxin originated from yeast, respectively. These results confirm that BDAI-1 and protein Z are foam-positive factors and identify yeast thioredoxin as a possible novel foam

  19. K(alpha) X-ray Emission Spectra from Highly Charged Fe Ions in EBIT

    SciTech Connect

    Jacobs, V; Beiersdorfer, P

    2007-03-29

    A detailed spectral model has been developed for the computer simulation of the 2p {yields} 1s K{alpha} X-ray emission from highly charged Fe ions in the Electron Beam Ion Trap (EBIT). The spectral features of interest occur in the range from 1.84 {angstrom} to 1.94 {angstrom}. The fundamental radiative emission processes associated with radiationless electron capture or dielectronic recombination, inner-shell electron collisional excitation, and inner-shell electron collisional ionization are taken in account. For comparison, spectral observations and simulations for high-temperature magnetic-fusion (Tokamak) plasmas are reviewed. In these plasmas, small departures from steady-state corona-model charge-state distributions can occur due to ion transport processes, while the assumption of equilibrium (Maxwellian) electron energy distributions is expected to be valid. Our investigations for EBIT have been directed at the identification of spectral features that can serve as diagnostics of extreme non-equilibrium or transient-ionization conditions, and allowance has been made for general (non-Maxwellian) electron energy distributions. For the precise interpretation of the high-resolution X-ray observations, which may involve the analysis of blended spectral features composed of many lines, it has been necessary to take into account the multitude of individual fine-structure components of the K{alpha} radiative transitions in the ions from Fe XVIII to Fe XXV. At electron densities higher than the validity range of the corona-model approximation, collisionally induced transitions among low-lying excited states can play an important role. It is found that inner-shell electron excitation and ionization processes involving the complex intermediate ions from Fe XVIII to Fe XXI produce spectral features, in the wavelength range from 1.89 {angstrom} to 1.94 {angstrom}, which are particularly sensitive to density variations and transient ionization conditions.

  20. Towards high throughput screening of electrochemical stability of battery electrolytes.

    PubMed

    Borodin, Oleg; Olguin, Marco; Spear, Carrie E; Leiter, Kenneth W; Knap, Jaroslaw

    2015-09-01

    High throughput screening of solvents and additives with potential applications in lithium batteries is reported. The initial test set is limited to carbonate and phosphate-based compounds and focused on their electrochemical properties. Solvent stability towards first and second reduction and oxidation is reported from density functional theory (DFT) calculations performed on isolated solvents surrounded by implicit solvent. The reorganization energy is estimated from the difference between vertical and adiabatic redox energies and found to be especially important for the accurate prediction of reduction stability. A majority of tested compounds had the second reduction potential higher than the first reduction potential indicating that the second reduction reaction might play an important role in the passivation layer formation. Similarly, the second oxidation potential was smaller for a significant subset of tested molecules than the first oxidation potential. A number of potential sources of errors introduced during screening of the electrolyte electrochemical properties were examined. The formation of lithium fluoride during reduction of semifluorinated solvents such as fluoroethylene carbonate and the H-transfer during oxidation of solvents were found to shift the electrochemical potential by 1.5-2 V and could shrink the electrochemical stability window by as much as 3.5 V when such reactions are included in the screening procedure. The initial oxidation reaction of ethylene carbonate and dimethyl carbonate at the surface of the completely de-lithiated LiNi0.5Mn1.5O4 high voltage spinel cathode was examined using DFT. Depending on the molecular orientation at the cathode surface, a carbonate molecule either exhibited deprotonation or was found bound to the transition metal via its carbonyl oxygen. PMID:26266636

  1. Towards high throughput screening of electrochemical stability of battery electrolytes

    NASA Astrophysics Data System (ADS)

    Borodin, Oleg; Olguin, Marco; Spear, Carrie E.; Leiter, Kenneth W.; Knap, Jaroslaw

    2015-09-01

    High throughput screening of solvents and additives with potential applications in lithium batteries is reported. The initial test set is limited to carbonate and phosphate-based compounds and focused on their electrochemical properties. Solvent stability towards first and second reduction and oxidation is reported from density functional theory (DFT) calculations performed on isolated solvents surrounded by implicit solvent. The reorganization energy is estimated from the difference between vertical and adiabatic redox energies and found to be especially important for the accurate prediction of reduction stability. A majority of tested compounds had the second reduction potential higher than the first reduction potential indicating that the second reduction reaction might play an important role in the passivation layer formation. Similarly, the second oxidation potential was smaller for a significant subset of tested molecules than the first oxidation potential. A number of potential sources of errors introduced during screening of the electrolyte electrochemical properties were examined. The formation of lithium fluoride during reduction of semifluorinated solvents such as fluoroethylene carbonate and the H-transfer during oxidation of solvents were found to shift the electrochemical potential by 1.5-2 V and could shrink the electrochemical stability window by as much as 3.5 V when such reactions are included in the screening procedure. The initial oxidation reaction of ethylene carbonate and dimethyl carbonate at the surface of the completely de-lithiated LiNi0.5Mn1.5O4 high voltage spinel cathode was examined using DFT. Depending on the molecular orientation at the cathode surface, a carbonate molecule either exhibited deprotonation or was found bound to the transition metal via its carbonyl oxygen.

  2. High Volume Manufacturing and Field Stability of MEMS Products

    NASA Astrophysics Data System (ADS)

    Martin, Jack

    Low volume MEMS/NEMS production is practical when an attractive concept is implemented with business, manufacturing, packaging, and test support. Moving beyond this to high volume production adds requirements on design, process control, quality, product stability, market size, market maturity, capital investment, and business systems. In a broad sense, this chapter uses a case study approach: It describes and compares the silicon-based MEMS accelerometers, pressure sensors, image projection systems, and gyroscopes that are in high volume production. Although they serve several markets, these businesses have common characteristics. For example, the manufacturing lines use automated semiconductor equipment and standard material sets to make consistent products in large quantities. Standard, well controlled processes are sometimes modified for a MEMS product. However, novel processes that cannot run with standard equipment and material sets are avoided when possible. This reliance on semiconductor tools, as well as the organizational practices required to manufacture clean, particle-free products partially explains why the MEMS market leaders are integrated circuit manufacturers. There are other factors. MEMS and NEMS are enabling technologies, so it can take several years for high volume applications to develop. Indeed, market size is usually a strong function of price. This becomes a vicious circle, because low price requires low cost - a result that is normally achieved only after a product is in high volume production. During the early years, IC companies reduced cost and financial risk by using existing facilities for low volume MEMS production. As a result, product architectures are partially determined by capabilities developed for previous products. This chapter includes a discussion of MEMS product architecture with particular attention to the impact of electronic integration, packaging, and surfaces. Packaging and testing are critical, because they are

  3. High efficiency, high energy, CEP-stabilized infrared optical parametric amplifier

    NASA Astrophysics Data System (ADS)

    Ling, Weijun; Geng, Xiaotao; Guo, Shuyan; Wei, Zhiyi; Krausz, F.; Kim, D.

    2014-10-01

    A high efficiency, tunable, carrier-envelope-phase (CEP) stabilized near-infrared optical parametric amplifier (OPA) is demonstrated with just a single BBO crystal. A white-light continuum produced by a CEP-stabilized laser is seeded into the two stages of the type II OPA system. We achieved a pump-to-signal conversion efficiency of 34% with a single nonlinear crystal. To our knowledge this is the highest conversion efficiency reported in broadband optical parametric amplification, using the two stages. This work demonstrates a compact way to for tunable femtosecond pulses with CEP stabilization.

  4. High-temperature effect of hydrogen on sintered alpha-silicon carbide

    NASA Technical Reports Server (NTRS)

    Hallum, G. W.; Herbell, T. P.

    1986-01-01

    Sintered alpha-silicon carbide was exposed to pure, dry hydrogen at high temperatures for times up to 500 hr. Weight loss and corrosion were seen after 50 hr at temperatures as low as 1000 C. Corrosion of SiC by hydrogen produced grain boundary deterioration at 1100 C and a mixture of grain and grain boundary deterioration at 1300 C. Statistically significant strength reductions were seen in samples exposed to hydrogen for times greater than 50 hr and temperatures above 1100 C. Critical fracture origins were identified by fractography as either general grain boundary corrision at 1100 C or as corrosion pits at 1300 C. A maximum strength decrease of approximately 33 percent was seen at 1100 and 1300 C after 500 hr exposure to hydrogen. A computer assisted thermodynamic program was also used to predict possible reaction species of SiC and hydrogen.

  5. Treatment with interferon-alpha delays disease in swine infected with a highly virulent CSFV strain.

    PubMed

    Fernandez-Sainz, I; Ramanathan, P; O'Donnell, V; Diaz-San Segundo, F; Velazquez-Salinas, L; Sturza, D F; Zhu, J; de los Santos, T; Borca, M V

    2015-09-01

    Interferon-alpha (IFNα) can effectively inhibit or abort a viral infection within the host. It has been reported that IFN induction and production is hindered during classical swine fever virus (CSFV) infection. Most of those studies have been performed in vitro, making it difficult to elucidate the actual role of IFNs during CSFV infection in swine. Here, we report the effect of IFNα treatment (delivered by a replication defective recombinant human adenovirus type 5, Ad5) in swine experimentally infected with highly virulent CSFV strain Brescia. Treatment with two different subtypes of IFNα delayed the appearance of CSF-related clinical signs and virus replication although it did not prevent lethal disease. This is the first report describing the effect of IFNα treatment during CSFV infection in swine. PMID:26004252

  6. Validation of the F-18 high alpha research vehicle flight control and avionics systems modifications

    NASA Technical Reports Server (NTRS)

    Chacon, Vince; Pahle, Joseph W.; Regenie, Victoria A.

    1990-01-01

    The verification and validation process is a critical portion of the development of a flight system. Verification, the steps taken to assure the system meets the design specification, has become a reasonably understood and straightforward process. Validation is the method used to ensure that the system design meets the needs of the project. As systems become more integrated and more critical in their functions, the validation process becomes more complex and important. The tests, tools, and techniques which are being used for the validation of the high alpha research vehicle (HARV) turning vane control system (TVCS) are discussed and the problems and their solutions are documented. The emphasis of this paper is on the validation of integrated system.

  7. A high performance spectral code for nonlinear MHD stability

    SciTech Connect

    Taylor, M.

    1992-09-01

    A new spectral code, NSTAB, has been developed to do nonlinear stability and equilibrium calculations for the magnetohydrodynamic (MHD) equations in three dimensional toroidal geometries. The code has the resolution to test nonlinear stability by calculating bifurcated equilibria directly. These equilibria consist of weak solutions with current sheets near rational surfaces and other less localized modes. Bifurcated equilibria with a pronounced current sheet where the rotational transform crosses unity are calculated for the International Thermonuclear Experimental Reactor (ITER). Bifurcated solutions with broader resonances are found for the LHD stellarator currently being built in Japan and an optimized configuration like the Wendelstein VII-X proposed for construction in Germany. The code is able to handle the many harmonics required to capture the high mode number of these instabilities. NSTAB builds on the highly successful BETAS code, which applies the spectral method to a flux coordinate formulation of the variational principle associated with the MHD equilibrium equations. However, a new residue condition for the location of the magnetic axis has been developed and implemented. This condition is based on the weak formulation of the equations and imposes no constraints on the inner flux surfaces.

  8. A Novel High-Throughput 1536-well Notch1 γ-Secretase AlphaLISA Assay

    PubMed Central

    Chau, De-ming; Shum, David; Radu, Constantin; Bhinder, Bhavneet; Gin, David; Gilchrist, M. Lane; Djaballah, Hakim; Li, Yue-Ming

    2013-01-01

    The Notch pathway plays a crucial role in cell fate decisions through controlling various cellular processes. Overactive Notch signal contributes to cancer development from leukemias to solid tumors. γ-Secretase is an intramembrane protease responsible for the final proteolytic step of Notch that releases the membrane-tethered Notch fragment for signaling. Therefore, γ-secretase is an attractive drug target in treating Notch-mediated cancers. However, the absence of high-throughput γ-secretase assay using Notch substrate has limited the identification and development of γ-secretase inhibitors that specifically target the Notch signaling pathway. Here, we report on the development of a 1536-well γ-secretase assay using a biotinylated recombinant Notch1 substrate. We effectively assimilated and miniaturized this newly developed Notch1 substrate with the AlphaLISA detection technology and demonstrated its robustness with a calculated Z’ score of 0.66. We further validated this optimized assay by performing a pilot screening against a chemical library consisting of ~5,600 chemicals and identified known γ-secretase inhibitors e.g. DAPT, and Calpeptin; as well as a novel γ-secretase inhibitor referred to as KD-I-085. This assay is the first reported 1536-well AlphaLISA format and represents a novel high-throughput Notch1-γ-secretase assay, which provides an unprecedented opportunity to discover Notch-selective γ-secretase inhibitors that can be potentially used for the treatment of cancer and other human disorders. PMID:23448293

  9. High Volume Manufacturing and Field Stability of MEMS Products

    NASA Astrophysics Data System (ADS)

    Martin, Jack

    Low volume MEMS/NEMS production is practical when an attractive concept is implemented with business, manufacturing, packaging, and test support. Moving beyond this to high volume production adds requirements on design, process control, quality, product stability, market size, market maturity, capital investment, and business systems. In a broad sense, this chapter uses a case study approach: It describes and compares the silicon-based MEMS accelerometers, pressure sensors, image projection systems, and gyroscopes that are in high volume production. Although they serve several markets, these businesses have common characteristics. For example, the manufacturing lines use automated semiconductor equipment and standard material sets to make consistent products in large quantities. Standard, well controlled processes are sometimes modified for a MEMS product. However, novel processes that cannot run with standard equipment and material sets are avoided when possible. This reliance on semiconductor tools, as well as the organizational practices required to manufacture clean, particle-free products partially explains why the MEMS market leaders are integrated circuit manufacturers. There are other factors. MEMS and NEMS are enabling technologies, so it can take several years for high volume applications to develop. Indeed, market size is usually a strong function of price. This becomes a vicious circle, because low price requires low cost - a result that is normally achieved only after a product is in high volume production. During the early years, IC companies reduced cost and financial risk by using existing facilities for low volume MEMS production. As a result, product architectures are partially determined by capabilities developed for previous products. This chapter includes a discussion of MEMS product architecture with particular attention to the impact of electronic integration, packaging, and surfaces. Packaging and testing are critical, because they are

  10. Subsonic investigations of vortex interaction control for enhanced high-alpha aerodynamics of a chine forebody/Delta wing configuration

    NASA Technical Reports Server (NTRS)

    Rao, Dhanvada M.; Bhat, M. K.

    1992-01-01

    A proposed concept to alleviate high alpha asymmetry and lateral/directional instability by decoupling of forebody and wing vortices was studied on a generic chine forebody/ 60 deg. delta configuration in the NASA Langley 7 by 10 foot High Speed Tunnel. The decoupling technique involved inboard leading edge flaps of varying span and deflection angle. Six component force/moment characteristics, surface pressure distributions and vapor-screen flow visualizations were acquired, on the basic wing-body configuration and with both single and twin vertical tails at M sub infinity = 0.1 and 0.4, and in the range alpha = 0 to 50 deg and beta = -10 to +10 degs. Results are presented which highlight the potential of vortex decoupling via leading edge flaps for enhanced high alpha lateral/directional characteristics.